2007-21A
Appendices to
Evaluating the Effectiveness
of the Minnesota Speed Management Program
Office of Traffic, Safety and Operations
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Transportation Research
Technical Report Documentation Page
1. Report No.
MN/RC-2007-21A
2.
4. Title and Subtitle
Appendices to Evaluating the Effectiveness of the Minnesota
Speed Management Program
3. Recipients Accession No.
5. Report Date
May 2007
6.
7. Author(s)
8. Performing Organization Report No.
9. Performing Organization Name and Address
10. Project/Task/Work Unit No.
Kathleen A. Harder, Ph.D. and John R. Bloomfield, Ph.D.
Center for Human Factors Systems Research and Design
College of Design
University of Minnesota
Suite 225
1425 University Ave. S.E.
Minneapolis, MN 55414
12. Sponsoring Organization Name and Address
Minnesota Department of Transportation
395 John Ireland Boulevard Mail Stop 330
St. Paul, Minnesota 55155
11. Contract (C) or Grant (G) No.
(c) 81655 (wo) 199
13. Type of Report and Period Covered
Final Report
14. Sponsoring Agency Code
15. Supplementary Notes
http://www.lrrb.org/PDF/200721A.pdf
This report contains the appendices to report number 2007-21.
16. Abstract (Limit: 200 words)
The Minnesota Speed Management Program (MSMP), a cooperative project between the Minnesota Department of
Transportation and the Minnesota Department of Public Safety, was developed within the framework of the
Minnesota Comprehensive Highway Safety Plan. The overall goal was to reduce the number of fatal and lifechanging crashes on Minnesota highways. The MSMP involved a speed limit adjustment—on 850 miles of
Minnesota’s 55 mph highways the speed limit was increased to 60 mph. It involved increased speed
enforcement—by State Patrol, county sheriffs, and local law enforcement—on selected highways. There were four
waves of Enhanced Enforcement (one of six weeks, three of eight weeks) each followed by four weeks of Regular
Enforcement. The MSMP involved extensive public education, organized by the Office of Traffic Safety, with
approximately 10,000 public service messages presented on the radio.
Two evaluation efforts were conducted. The University of Minnesota compared travel speed data and crash data
obtained during the MSMP with historical data. Throughout the MSMP, there were decreases in the number of
drivers traveling at least 10 mph above the speed limits—decreases of -28.7% on 2-Lane/2-Way Highways; -28.7%
on 4-Lane Divided Highways; -42.9% on Rural Freeways; and -11.2% mph on Urban Freeways. The University’s
evaluation also showed there were reductions in the numbers of fatal and life-changing crashes during the MSMP.
MarketLine Research conducted the second evaluation, using telephone surveys, and found nine in ten drivers
support the speed limit increase from 55 mph to 60 mph in both Metro and Greater Minnesota. The MSMP, in
concert with other efforts that are part of the Minnesota Comprehensive Highway Safety Plan, resulted in
reductions in the number of speeders on Minnesota Highways and reductions in the number of fatal and lifechanging crashes—making Minnesota’s roads safer.
17. Document Analysis/Descriptors
18. Availability Statement
Speed management;
Speed limit changes
Enhanced speed enforcement
Speed data
Crash data
No restrictions. Document available from:
National Technical Information Services,
Springfield, Virginia 22161
19. Security Class (this report)
20. Security Class (this page)
21. No. of Pages
Unclassified
Unclassified
644
22. Price
Appendices to
Evaluating the Effectiveness of the
Minnesota Speed Management Program
Final Report
Prepared by:
Kathleen A. Harder, Ph.D.
John R. Bloomfield, Ph.D.
Center for Human Factors Systems Research and Design
University of Minnesota
May 2007
Published by
Minnesota Department of Transportation
Research Services Section
Mail Stop 330
395 John Ireland Boulevard
St. Paul, Minnesota 55155-1899
This report represents the results of research conducted by the authors and does not
necessarily represent the view or policy of the Minnesota Department of Transportation
and/or the Center for Transportation Studies. This report does not contain a standard or
specified technique.
Appendix 1
Minnesota Speed Management Project: Deliverable #2—
Historical Data
Kathleen A. Harder, Ph.D. and John R. Bloomfield, Ph.D.
Center for Human Factors Systems Research and Design
University of Minnesota, Suite 225
1425 University Ave. S.E.
Minneapolis, MN 55414
Content
Page
Section 1: Introduction ..……………………………………………………………....3
1.1 Background ……………………………………………………………….3
1.2 Organization of This Report ……………………………………………..6
Section 2. 2-Lane/2-Way Highway Speed Data ....……………………………………8
2.1 Historical Speed Data from ATRs Located Within Enhanced
Enforcement Zones ……………………………………………………….8
2.2 Historical Speed Data from Tubes Located Within Enhanced
Enforcement Zones ………………………………………………………21
2.3 Historical Speed Data from Tube Located Outside Enhanced
Enforcement Zones but in Zone with Change in Speed Limit …………..24
2.4 Historical Speed Data from ATRs Located Outside Enhanced
Enforcement Zones and Outside Speed Limit Change Zones …………..25
Section 3: 4-Lane Divided Highway Speed Data ……………………………………42
3.1 Historical Speed Data from ATRs Located Within Enhanced
Enforcement Zones……………………………………………………….42
3.2 Historical Speed Data from Tube Located Within an Enhanced
Enforcement Zone ………………………………………………………59
3.3 Historical Speed Data from ATRs Located Outside Enhanced
Enforcement Zones ……………………………………………………..60
Section 4: .Rural Freeways Speed Data………………………………………………64
4.1 Historical Speed Data from ATRs Located Within Enhanced
Enforcement Zones……………………………………………………….64
4.2 Historical Speed Data from Tube Located Within an Enhanced
Enforcement Zone ………………………………………………………81
4.3 Historical Speed Data from ATR Located Outside the Enhanced
Enforcement Zones ……………………………………………………..82
Section 5: Urban Freeway Speed Data ………………………………………………84
5.1 Historical Speed Data from ATRs Located Within Enhanced
Enforcement Zones……………………………………………………….84
5.2 Historical Speed Data from ATR Located Outside the Enhanced
Enforcement Zones ……………………………………………………..86
Section 6: Historical Crash Data …………………………………………………..90
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Section 1: Introduction
1.1 Background
The Minnesota Speed Management Program (MSMP) is a cooperative project between
the Minnesota Department of Transportation (Mn/DOT) and the Minnesota Department
of Safety (DPS). The program, which began on 9/26/05 and ends on 8/13/06, involves:
• Raising the speed limit on select roadways in Minnesota from 55 mph to 60 mph
in order to align the speed limit more closely with the design speed of the
roadways.
• Increasing the presence of enforcement officers along selected areas of these
roadways and other high-design roadways for selected periods of time.
The MSMP involves the following four types of roadway—(1) 2-Lane/2-Way Highways,
(2) 4-Lane Divided Highways, (3) Rural Freeways, and (4) Urban Freeways.
The University of Minnesota’s involvement in the project was to assess the effectiveness
of the MSMP in reducing driver speed and fatal and “A” injury crashes. We analyzed
vehicle speed data collected by Mn/DOT in order to determine whether changes in driver
speeds occurred as a result of the MSMP. In addition, we analyzed fatal and “A” injury
crashes to determine whether the program produced changes in crash rates. We used
historical speed data and crash data for comparison purposes. We also obtained citation
data—but only for the time period in which the MSMP was conducted.
In our analysis, we used speed data obtained both in periods in which there was enhanced
enforcement on some roadways and in periods in which there was normal enforcement
on those same roads. The schedule of the enhanced enforcement and normal
enforcement periods is presented in Table 1.
Table 1.1: Enforcement Status During the MSMP
Enforcement status
Enhanced Enforcement Period #1
Normal Enforcement Period #1
Enhanced Enforcement Period #2.
Normal Enforcement Period #2
Enhanced Enforcement Period #3.
Normal Enforcement Period #3
Enhanced Enforcement Period #4
Normal Enforcement Period #4
Time Period
9/26/05 to 11/6/05
11/7/05 to 12/4/05
12/5/05 to 1/29/06
1/30/06 to 2/26/06
2/27/06 to 4/23/06
4/24/06 to 5/21/06
5/22/06 to 7/16/06
7/17/06 to 8/13/06
As the table shows the program began with a six-week period of enhanced enforcement.
This was followed by a four-week period of normal enforcement. The remaining three
enhanced enforcement periods were all eight weeks in length, and each was followed by
a four-week period of normal enforcement.
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The first step in the analysis process was to analyze historical speed data, in order to
provide a baseline against which the data collected in the MSPM could be compared.
The historical speed data are presented in the following sections of this report.
In the MSMP, Mn/DOT collected speed data from 21 Automated Traffic Recorders
(ATRs) and seven Data-Recording Tubes. The 21 ATRs are listed in Table 1.2. In the
table, the ATRs are organized in terms of the type of roadway on which they are
located—i.e., whether they are on 2-Lane/2-Way Highways, 4-Lane Divided Highways,
Rural Freeways, or Urban Freeways. The table lists their locations, the speed limit at the
location—and whether or not the speedlimit was changed for the MSMP—and whether
the ATRs were located Within or Outside an Enhanced Enforcement Zone. As the table
shows, seven ATRs were located on 2-Lane/2-Way Highways, five on 4-Lane Divided
Highways, five on Rural Freeways, and four on Urban Freeways.
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Table 1.2: ATRs Organized by Road Type
Type of
roadway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
ATR
210
219
220
179
198
199
222
4-Lane Divided
Highway
197
4-Lane Divided
Highway
4-Lane Divided
Highway
4-Lane Divided
Highway
4-Lane Divided
Highway
172
Rural Freeway
175
Rural Freeway
191
Rural Freeway
208
Rural Freeway
227
Rural Freeway
200
Urban Freeway
100
187
188
353
Urban Freeway
I94
Urban Freeway
35WC
D
335
Urban Freeway
Location
US-71, 1 mile North of
Blackduck, Beltrami
US-2, South East of Warba,
Itasca
US-71, South of CR 89,
Hubbard
USTH 59, South of Garvin,
Lyon
USTH 212, East of TH 23,
Chippewa
USTH 75, 0.55 miles N of
Co Rd. 69, Pipestone
MNTH 65, near Pliny,
Aitkin
Speed limit
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Unchanged at 55 mph
Within/
Outside
Enforcement Zone
Within
Within
Within
Outside
Unchanged at 55 mph
Outside
Unchanged at 55 mph
Outside
Unchanged at 55 mph
Outside
SR-60, 0.7 miles West of
junction with SR-4, (St.
James) Watonwan
US-10, West of Dilworth,
Clay
US-10, 0.8 miles West of
Rice, Benton
US-52, North of Rochester,
Olmstead
TH 169, South of CR 59,
North of Jordan, Scott
Unchanged at 65 mph
Within
Unchanged at 65 mph
Within
Unchanged at 65 mph
Within
Unchanged at 65 mph
Within
Unchanged at 65 mph
Outside
I-94, 0.5 miles South East
of Saulk Centre, Stearns
I-35, North of Wyoming,
Chisago
I-35, North of Owatanna,
Steele
I-90, East of Alden,
Freeborn
I-94, Hasty, Wright
Unchanged at 70 mph
Within
Unchanged at 70 mph
Within
Unchanged at 70 mph
Within
Unchanged at 70 mph
Within
Unchanged at 70 mph
Outside
Highway 100, near
Brooklyn Center, Hennepin
I-94, South of 57th Street
Bridge, Hennepin
I-35W, near Roseville,
Ramsey
I-35W at County Road 53,
Anoka
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Unchanged at 55 mph
Within
A1-5
Within
Within
Outside
In addition to the ATRs, there were seven locations at which there are Data-Recording
Tubes. The seven Tubes are listed in Table 1.3. They are organized in terms of the type
of roadway on which they were located. The table gives the locations of the Tubes,
whether they collected data from all lanes or from only the lanes in one direction, the
speed limit at the location—and whether or not the speed limit was changed for the
MSMP—and whether the Tubes were located Within or Outside the Enhanced
Enforcement Zones.
Table 1.3: Tubes Organized by Road Type
Within/
Outside
Enforcement Zone
Within
Type of
roadway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
Tube
Number
(Lanes
Covered)
T01
(All)
T02
(All)
T03
(All)
T04
(Westbound)
T08
(All)
Location
MN-23, Hanley Falls,
Lyon
MN-7, Montevideo,
Chippewa
US-71, Willmar,
Kandiyohi
MN-7, Silver Lake,
McLeod
US-53, Ash Lake, St
Louis
Speed limit
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
4-Lane Divided
Highway
T05
(Eastbound)
MN-60, Lake Crystal,
Blue Earth
Unchanged at 65 mph
Within
Rural Freeway
T06
(Eastbound)
T07
(All)
I-94, Fergus Falls, Otter
Tail
I-35, Cloquet, Carlton
Unchanged at 70 mph
Within
Unchanged at 70 mph
Within
Rural Freeway
Within
Within
Within
Outside
1.2. Organization of this Report
Historical speed data from the 21 ATRs and seven Tubes are presented in the next four
section of this report—historical speed data from 2-Lane/2-Way Highways, 4-Lane
Divided Highways, Rural Freeways, and Urban Freeways are presented in Section 2,
Section 3, Section 4, Section and 5, respectively.
The historical data are limited for the seven Tubes and for three the ATRs located on
Urban Freeways. For each of the Tubes, the available historical data were collected in a
one-week period in August 2005, shortly before the MSMP began. The three ATRs
located on Urban Freeways were installed in the summer of 2005—for ATR-100, two
A1-6
weeks of data were collected in September 2005, while for ATR-I94 and ATR-35WCD
four weeks of data were collected in August and September 2005.
For the remaining 18 ATRs, there were historical data from the same time periods that
were used in the MSMP. In some cases, three years of historical speed data were
available; in others, only one or two years of historical data were available.
Following the four sections that present historical speed data, the fifth and final section of
the report presents historical crash data.
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Section 2: 2-Lane/2-Way Highway Speed Data
The historical speed data obtained from the seven ATRs and five Tubes that were located
on 2-Lane/2-Way Highways are presented in this section of the report.
Three of the seven ATRs were located Within Enhanced Enforcement Zones, while the
remaining four were located Outside Enhanced Enforcement Zones. During the MSMP,
at the locations of the three ATRs Within the Enhanced Enforcement Zones, the speed
limit was increased from 55 mph to 60 mph. In contrast, at the locations of the four
ATRs Outside the Enhanced Enforcement Zones, the speed limit remained unchanged at
55 mph.
Four of the five Tubes were located Within Enhanced Enforcement Zones, while the
remaining Tube was located Outside the Enhanced Enforcement Zones. However at all
five Tube locations—the Tube located Outside the Enhanced Enforcement Zones—the
speed limit was increased from 55 mph to 60 mph.
2.1. Historical Speed Data from ATRs Located Within Enhanced Enforcement Zones
The three ATRs located Within Enhanced Enforcement Zones on 2-Lane/2-Way
Highways were as follows: (1) ATR-210, on US-71, near Blackduck in Beltrami County,
(2) ATR-219, on US-2, near Warba in Itasca County, and (3) ATR-220, on US-71, South
of CR 89 in Hubbard County. For these three ATRs, there were historical data from the
same time periods that were used in the MSMP. In some cases, three years of historical
speed data were available; in others, one or two years of historical data were available.
A1-8
ATR-210
The historical speed data for ATR-210 are presented in Tables 2.1 through 2.8.
Table 2.1: ATR-210—Three Prior Years of Historical Speed Data for Six-Week
Period from 9/26 to 11/6
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
60.9099284
8.20577853
61.3635283
55.2005335
67.9055718
69.3862473
72.7496133
59.48377
0.24811643
0.07927457
0.02604059
0.00825477
0.00298489
48,578
2003-2004
60.56549
8.281824
61.17443
55.04355
67.58861
69.12559
72.20098
60.5921
0.234211
0.071554
0.022589
0.005776
0.00218
52,282
2004-2005
61.40966
7.58461
61.66768
55.57972
68.09323
69.51765
72.94356
59.7873
0.258579
0.083068
0.026898
0.007583
0.002741
54,726
Table 2.2: ATR-210—Three Prior Years of Historical Speed Data for Four-Week
Period from 11/7 to 12/4
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
59.915
8.7779
60.735
53.321
67.343
68.921
71.783
58.591
0.22423
0.065806
0.021478
0.0059229
0.0023380
32,079
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2003-2004
60.039
8.1524
60.713
53.797
67.079
68.670
71.016
60.749
0.21533
0.058197
0.017874
0.0049350
0.0017754
33,232
2004-2005
60.932
7.8987
61.397
55.191
67.836
69.242
72.336
59.329
0.25080
0.073069
0.023693
0.0066107
0.0023986
34,187
Table 2.3: ATR-210—Three Prior Years of Historical Speed Data for Eight-Week
Period from 12/5 to 1/29
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
60.551
8.42853
61.13686
54.51279
67.77133
69.24329
72.49436
58.5905
0.244138
0.074296
0.025594
0.006435
0.002595
55,481
2003-2004
59.753
8.615709
60.51694
53.25793
67.12141
68.72718
71.24467
58.4992
0.216055
0.060368
0.018719
0.004813
0.001705
56,305
2004-2005
58.48145
9.341494
59.44614
51.25359
66.36898
68.25588
70.5037
51.4271
0.186276
0.053783
0.016228
0.00395
0.001447
53,920
Table 2.4: ATR-210—Three Prior Years of Historical Speed Data for Four-Week
Period from 1/30 to 2/26
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
60.675
8.2006
61.279
55.104
67.652
69.137
72.158
60.308
0.23930
0.070921
0.022450
0.0056678
0.0021346
27,171
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2003-2004
60.833
7.7114
61.194
55.111
67.736
69.199
72.315
59.513
0.24352
0.072621
0.023760
0.0049929
0.0017217
29,041
2004-2005
61.073
7.6273
61.378
55.326
67.849
69.319
72.543
59.903
0.24693
0.076837
0.024073
0.0062711
0.0025624
29,660
Table 2.5: ATR-210—Three Prior Years of Historical Speed Data for Eight-Week
Period from 2/27 to 4/23
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Four Weeks Only
2/27/03 to 3/26/03)
60.830
8.0468
61.329
55.246
67.725
69.194
72.297
60.396
0.24272
0.072575
0.023426
0.0063125
0.0020433
27,406
2003-2004
2004-2005
(All Eight Weeks)
59.9019
8.210992
60.45495
53.75037
66.88127
68.63977
71.35655
61.3908
0.203491
0.061324
0.019585
0.005203
0.001762
59,585
(All Eight Weeks)
61.11259
7.734233
61.42962
55.4515
67.82317
69.34723
72.6631
60.799
0.24262
0.078585
0.024917
0.007016
0.002897
59,719
Table 2.6: ATR-210—Three Prior Years of Historical Speed Data for Four-Week
Period from 4/24 to 5/21
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
60.959
7.8206
61.395
55.466
67.564
69.152
72.344
62.276
0.23073
0.073311
0.023585
0.0059262
0.0023765
33,242
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2003-2004
60.275
8.2432
60.802
54.808
67.170
68.888
71.838
62.501
0.21315
0.067623
0.019679
0.0054145
0.0024453
34,352
2004-2005
61.140
7.4880
61.485
55.593
67.649
69.177
72.256
62.102
0.23665
0.073070
0.021942
0.0056605
0.0020694
32,859
Table 2.7: ATR-210—Three Prior Years of Historical Speed Data for Eight-Week
Period from 5/22 to 7/16
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
61.15629
7.666349
61.54294
55.52223
67.83211
69.35392
72.57796
61.1618
0.243051
0.078773
0.022968
0.00605
0.002113
76,194
2003-2004
60.17311
9.465533
61.17891
54.59599
67.69237
69.29561
72.5974
60.5467
0.233967
0.078032
0.02407
0.006634
0.002646
77,481
2004-2005
61.5863876
7.2983362
61.7492381
55.8979156
68.0372026
69.5101531
72.9209815
61.430736
0.25309928
0.08337191
0.02624743
0.00720165
0.00264918
77,760
Table 2.8: ATR-210—Two Prior Years of Historical Speed Data for Eight-Week
Period from 7/17 to 8/13 [No Speed Data Available for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
61.493
7.8967
61.866
55.732
68.246
69.655
73.075
60.034
0.26517
0.087748
0.026363
0.0075602
0.0028534
41,004
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2003-2004
62.020
7.6742
62.171
56.116
68.643
69.962
73.684
59.493
0.28802
0.098571
0.032654
0.0081573
0.0033460
40,945
ATR-219
The historical speed data for ATR-210 are presented in Tables 2.9 through 2.16.
Table 2.9: ATR-219—Three Prior Years of Historical Speed Data for Six-Week
Period from 9/26 to 11/6
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
61.4545416
5.63946714
61.4020475
56.3149367
66.661964
68.4027784
70.5075952
68.524519
0.19773524
0.0541243
0.01349842
0.0029387
0.00109058
153,129
2003-2004
62.24973
5.214479
62.32598
57.75922
66.60045
68.24977
69.89908
73.9637
0.198519
0.046941
0.012237
0.003209
0.000881
149,870
2004-2005
62.15082
4.75036
62.21822
57.78839
65.94424
67.77809
69.61194
75.9257
0.175745
0.03942
0.009523
0.002273
0.000656
147,845
Table 2.10: ATR-219—Three Prior Years of Historical Speed Data for Four-Week
Period from 11/7 to 12/4
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
61.253
6.0923
61.305
56.039
66.796
68.538
70.915
67.123
0.20155
0.058046
0.014079
0.0029312
0.0011436
90,066
A1-13
2003-2004
61.448
6.0942
61.971
56.847
65.761
67.658
69.554
73.522
0.17006
0.038255
0.0096481
0.0026186
0.00087286
85,924
2004-2005
61.780
5.1576
62.064
57.359
65.350
67.383
69.415
75.926
0.15861
0.035618
0.0085830
0.0024052
0.00076636
84,817
Table 2.11: ATR-219—Three Prior Years of Historical Speed Data for Eight-Week
Period from 12/4 to 1/29
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
2003-2004
(All Eight Weeks)
61.44293
5.904898
61.42483
56.1638
66.98552
68.64187
71.01288
66.6566
0.209937
0.059002
0.014563
0.00304
0.00116
161,163
(All Eight Weeks)
61.05499
5.702989
61.58472
56.33299
64.97067
67.0432
69.2183
74.1399
0.146968
0.032031
0.007056
0.001922
0.000513
159,722
2004-2005
(Four Weeks Only
1/2/05 to 1/29/05)
59.482
6.5452
60.342
55.004
64.465
65.277
68.275
71.177
0.10462
0.021237
0.0047164
0.0012321
0.00051668
75,482
Table 2.12: ATR-219—Two Prior Years of Historical Speed Data for Four-Week
Period from 1/30 to 2/26 [No Speed Data Available for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
61.265
5.9389
61.320
56.096
66.778
68.391
70.017
67.351
0.20514
0.050123
0.012778
0.0026532
0.00088858
79,903
A1-14
2003-2004
61.165
5.3284
61.592
56.475
64.966
66.984
69.120
74.711
0.14643
0.029397
0.0065136
0.0014994
0.00038099
81,368
Table 2.13: ATR-219—Two Prior Years of Historical Speed Data for Eight-Week
Period from 2/27 to 4/23 [No Speed Data Available for 2002-2003]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2003-2004
61.7728
5.138351
62.00928
57.05134
65.91457
67.74324
69.57192
73.5903
0.175006
0.038295
0.009353
0.002294
0.000624
169,994
2004-2005
61.7231
5.491703
61.83082
56.80269
66.4436
68.16081
69.87803
71.2422
0.192033
0.046449
0.012055
0.002979
0.000852
167,820
Table 2.14: ATR-219—Two Prior Years of Historical Speed Data for Four-Week
Period from 4/24 to 5/21 [No Speed Data Available for 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
61.808
5.5306
61.766
56.663
67.019
68.548
70.325
68.461
0.21605
0.052502
0.014054
0.0031988
0.0010488
95,349
A1-15
2004-2005
61.772
5.1589
61.979
57.312
65.382
67.405
69.428
75.987
0.15945
0.035848
0.0088816
0.0025090
0.00073273
90,074
Table 2.15: ATR-219—Three Prior Years of Historical Speed Data for Eight-Week
Period from 5/22 to 7/16
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
61.54402
5.176271
61.53452
56.49794
66.50686
68.09288
69.6789
69.8329
0.197504
0.039877
0.0103
0.002512
0.000901
251,949
2003-2004
61.63832
4.916338
61.80065
56.98479
65.37365
67.38645
69.39924
74.9598
0.159282
0.035076
0.008684
0.002203
0.000724
231,922
2004-2005
61.35449
5.243593
61.63368
56.78542
64.96722
67.03274
69.21575
75.8391
0.146558
0.032037
0.007693
0.001921
0.000531
231,635
Table 2.16: ATR-219—Three Prior Years of Historical Speed Data for Four-Week
Period from 7/17 to 8/13
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
61.894
5.3021
61.823
56.685
67.115
68.559
70.016
68.028
0.22320
0.050119
0.013305
0.0032247
0.0010552
135,517
A1-16
2003-2004
62.010
4.9336
62.072
57.345
66.199
67.955
69.711
73.903
0.18415
0.041773
0.0099687
0.0024386
0.00067517
125,894
2004-2005
61.633
5.1362
61.847
57.094
65.168
67.275
69.382
75.815
0.15398
0.035332
0.0089873
0.0022127
0.00061732
124,732
ATR-220
The historical speed data for ATR-220 are only available for one year prior to the MSMP.
These data are presented in Tables 2.17 through 2.24.
Table 2.17: ATR-220—One Prior Year of Historical Speed Data for Six-Week
Period from 9/26/04 to 11/6/04
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
61.21816
7.089705
61.66003
56.42243
66.49187
68.3612
70.7134
70.3863
0.189904
0.056166
0.012948
0.003965
0.001287
85,496
Table 2.18: ATR-220—One Prior Year of Historical Speed Data for Four-Week
Period from 11/7/04 to 12/4/04
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
61.228
6.9727
61.705
56.343
66.455
68.326
70.620
69.989
0.18891
0.055238
0.012970
0.0044650
0.0014033
47,033
A1-17
Table 2.19: ATR-220—One Prior Year of Historical Speed Data for Eight-Week
Period from 12/5/04 to 1/29/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
58.34441
8.974211
59.80818
52.27617
64.69889
66.48917
69.12041
57.6491
0.128298
0.033286
0.006576
0.001901
0.000599
76,790
Table 2.20: ATR-220—One Prior Year of Historical Speed Data for Four-Week
Period from 1/30/05 to 2/26/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
61.781
6.3000
61.988
56.854
66.871
68.581
70.943
70.093
0.20474
0.058478
0.013508
0.0044707
0.0013866
41,828
A1-18
Table 2.21: ATR-220—One Prior Year of Historical Speed Data for Eight-Week
Period from 2/27/05 to 4/23/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
61.90985
6.424617
62.03376
56.9225
67.10212
68.82985
71.63504
69.506
0.210834
0.066136
0.016791
0.005475
0.001947
84,749
Table 2.22: ATR-220—One Prior Year of Historical Speed Data for Four-Week
Period from 4/24/05 to 5/21/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
61.661
6.3069
61.855
56.813
66.555
68.394
70.750
71.089
0.19228
0.056327
0.014164
0.0044311
0.0014512
51,680
A1-19
Table 2.23: ATR-220—One Prior Year of Historical Speed Data for Eight-Week
Period from 5/22/05 to 7/16/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
60.90058
6.103531
61.17799
56.19502
65.24252
67.43965
69.63678
73.3843
0.155519
0.041734
0.009418
0.002881
0.000717
158,958
Table 2.24: ATR-220—One Prior Year of Historical Speed Data for Four-Week
Period from 7/17/05 to 8/13/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
61.095
6.1132
61.316
56.320
65.726
67.775
69.824
72.312
0.16772
0.045711
0.010729
0.0028296
0.00079754
91,531
A1-20
2.2. Historical Speed Data from Tubes Located Within Enhanced Enforcement Zones
The four Tubes located Within Enhanced Enforcement Zones on 2-Lane/2-Way
Highways were as follows: (1) T01, on MN-23, near Hanley Falls, in Lyon County, (2)
T02, on MN-7, near Montevideo, in Chippewa County, (3) T03, on US-71, near Willmar,
in Kandiyohi County, and (4) T04, on MN-7, near Silver Lake, in McLeod County. The
speed data from Tube 04 were collected only from the Westbound lane on MN-7; while
speed data were collected from all lanes for the other three Tubes. Seven days of PreMSMP speed data were collected from all four Tubes during August 2005. These speed
data are presented in Tables 2.25 though 2.28.
Table 2.25: Tube 01—Pre-MSMP Speed Data for One-Week Period from 8/22/05 to
8/29/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
60.325683
4.5581581
60.231135
56.077671
64.258253
64.833556
67.86099
83.17615
0.0855342
0.023433
0.0075403
0.0022041
0.0008507
25,861
A1-21
Table 2.26: Tube 02—Pre-MSMP Speed Data for One-Week Period from 8/17/05 to
8/24/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
59.787326
5.8148385
60.445471
55.373666
64.439017
65.05137
68.128805
75.88031
0.1008346
0.0195981
0.0051932
0.0018547
0.0005564
16,175
Table 2.27: Tube 03—Pre-MSMP Speed Data for One-Week Period from 8/17/05 to
8/24/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
59.65661
5.008484
59.8266
55.63927
64.01664
64.61524
66.61665
81.2349
0.067861
0.01262
0.003521
0.001127
0.000535
35,499
A1-22
Table 2.28: Tube 04—Pre-MSMP Speed Data (Westbound Only) for One-Week
Period from 8/17/05 to 8/24/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
58.30134
4.720248
58.34843
54.70932
63.01153
63.84266
64.67379
75.4785
0.030376
0.00474
0.001279
0.000312
0.000187
32,065
A1-23
2.3. Historical Speed Data from Tube Located Outside Enhanced Enforcement Zones but
in Zone with Change in Speed Limit
The speed limit was changed from 55 mph to 60 mph at the location of the single Tube
that was on a 2-Lane/2-Way Highway Outside the Enhanced Enforcement Zones. It was
Tube 08 located on US-53, near Ash Lake, in St Louis County. Seven days of PreMSMP speed data were collected from this Tube during August 2005. These speed data
are presented in Table 2.29.
Table 2.29: Tube 08—Pre-MSMP Speed Data for One-Week Period from 8/19/05 to
8/26/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
61.59381
4.933043
61.55207
56.65734
65.95533
67.83777
69.72022
72.0833
0.175375
0.042569
0.011449
0.00281
0.00118
28,824
A1-24
2.4. Historical Speed Data from ATRs Located Outside Enhanced Enforcement Zones
and Outside Speed Limit Change Zones
There were four ATRs located Outside Enhanced Enforcement Zones on 2-Lane/2-Way
Highways. And, at these locations, the speed limits remained unchanged—at 55 mph.
The ATRs were—(1) ATR-179, on USTH 59, near Garvin, in Lyon County, (2) ATR198, on USTH 212, East of TH 23, in Chippewa County, (3) ATR-199, on USTH 75,
North of CR 69, in Pipestone County, and (4) ATR-222, on MNTH 65, near Pliny, in
Aitkin County. For these four ATRs, there were historical data from the same time
periods that were used in the MSMP. In some cases, three years of historical speed data
were available; in others, one or two years of historical data are available.
A1-25
ATR-179
The historical speed data for ATR-179 are presented in Tables 2.30 through 2.37.
Table 2.30: ATR-179—One Prior Year of Historical Speed Data for Six-Week
Period from 9/26 to 11/6 [No Speed Data Available for 2002-2003 and 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
55.741693
6.9966738
56.567861
50.822847
61.749015
63.027159
64.305302
66.48951
0.022824
0.0040704
0.0007934
0.000253
0.0001265
86,970
Table 2.31: ATR-179—One Prior Year of Historical Speed Data for Four-Week
Period from 11/7 to 12/4 [No Speed Data Available for 2002-2003 and 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
54.69628
8.992427
56.32824
50.31469
61.56748
62.88902
64.21055
63.7405
0.020132
0.00349
0.00079
0.000239
0.000091841
54,442
A1-26
Table 2.32: ATR-179—One Prior Year of Historical Speed Data for Eight-Week
Period from 12/5 to 1/29 [No Speed Data Available for 2002-2003 and 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
55.04436
7.401341
56.03896
50.28002
61.1992
62.63677
64.07434
67.3271
0.017805
0.003445
0.000767
0.000368
0.000099579
100,423
Table 2.33: ATR-179—One Prior Year of Historical Speed Data for Four-Week
Period from 1/30 to 2/26 [No Speed Data Available for 2002-2003 and 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
55.27112
7.367681
56.31544
50.46751
61.3854
62.75119
64.11698
66.9743
0.017674
0.002716
0.000601
0.000369
0.000116
51,545
A1-27
Table 2.34: ATR-179—One Prior Year of Historical Speed Data for Eight-Week
Period from 2/27 to 4/23 [No Speed Data Available for 2002-2003 and 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
55.67051
7.036101
56.56034
50.80554
61.66784
62.93526
64.20269
66.7772
0.018546
0.003231
0.000792
0.000315
0.000089986
111,128
Table 2.35: ATR-179—One Prior Year of Historical Speed Data for Four-Week
Period from 4/24 to 5/21 [No Speed Data Available for 2002-2003 and 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
55.84842
6.720427
56.65173
50.97122
61.66319
62.9242
64.18522
67.4091
0.017693
0.002763
0.00083
0.000287
0.000112
62,622
A1-28
Table 2.36: ATR-179—One Prior Year of Historical Speed Data for Eight-Week
Period from 5/22 to 7/16 [No Speed Data Available for 2002-2003 and 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
54.84319
7.167139
55.66912
50.15618
60.86442
62.4025
63.94059
67.2956
0.015561
0.00294
0.000687
0.000322
0.000122
139,775
Table 2.37: ATR-179—One Prior Year of Historical Speed Data for Four-Week
Period from 7/17 to 8/13 [No Speed Data Available for 2002-2003 and 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
55.33988
7.220464
56.2596
50.50438
61.4757
62.82215
64.1686
66.6991
0.019126
0.00342
0.000805
0.000216
0.00001437
69,590
A1-29
ATR-198
The historical speed data for ATR-198 are presented in Tables 2.38 through 2.45.
Table 2.38: ATR-198—Three Prior Years of Historical Speed Data for Six-Week
Period from 9/26 to 11/6
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
2003-2004
(One Week Only
31/10/02 to 11/6/02)
58.91761344
7.492985471
59.99234381
54.08116414
64.42934127
65.30560201
68.37813545
66.2700605
0.104973127
0.023607048
0.004694197
0.001224573
0.000408191
14,699
(Five Weeks Only
9/29/03 to
10/30/03)
58.49095122
8.125954867
59.78125385
53.65650578
64.29795222
64.93932163
68.06013782
63.9978702
0.095269624
0.021302982
0.003993652
0.001408288
0.000483442
95,151
2004-2005
(Three Weeks Only
9/30/05 to 10/13/04
plus
10/31/04 to 11/06/04)
58.6158626
7.61981099
59.8458075
53.6982272
64.2092175
64.8288305
67.6949438
65.371357
0.08618739
0.01904798
0.00379074
0.00107498
0.00033947
53,024
Table 2.39: ATR-198—Two Prior Years of Historical Speed Data for Four-Week
Period from 11/7 to 12/4 [Speed Data for 2003-2004 Unreliable]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
58.73466677
7.394136493
59.76492232
54.30724532
64.22057804
64.85365456
67.78646441
67.1774954
0.088441726
0.019462331
0.00333226
0.000965873
0.00030586
62,120
A1-30
2004-2005
58.15362
8.082772
59.42716
53.20819
64.05839
64.71456
67.29031
63.2124
0.078249
0.016578
0.003385
0.000884
0.00024
66,774
Table 2.40: ATR-198—Two Prior Years of Historical Speed Data for Eight-Week
Period from 12/5 to 1/29 [Speed Data for 2003-2004 Unreliable]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
58.6992883
7.297558202
59.78589609
54.04348032
64.17703561
64.80024203
67.55449094
66.7962812
0.08397337
0.017476031
0.003302762
0.001048909
0.000364084
115,358
2004-2005
57.4728433
8.23003797
58.7904634
51.9819271
63.7476402
64.4659895
66.2758461
59.978157
0.06283073
0.01254752
0.00240452
0.00075353
0.00024553
118,111
Table 2.41: ATR-198—Three Prior Years of Historical Speed Data for Four-Week
Period from 1/30 to 2/26
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
56.06043203
9.786298431
58.06396028
49.37385639
63.58956994
64.39791524
66.28379953
50.5412131
0.062758195
0.013068993
0.0022586
0.000791475
0.000308868
51,802
A1-31
2003-2004
55.93995
8.969012
57.69161
48.20833
63.40821
64.24839
65.58503
48.2584
0.055271
0.010225
0.001508
0.00041
0.000115
61,027
2004-2005
58.12176
7.603815
59.26312
53.2071
63.90403
64.56369
66.5545
64.2472
0.066929
0.012477
0.002195
0.000625
0.000169
59,227
Table 2.42: ATR-198—One Prior Year of Historical Speed Data for Eight-Week
Period from 2/27 to 4/23 [Speed Data for 2002-2003 & 2003-2004 Unreliable]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
57.9862091
7.88307417
59.1778739
52.8903799
63.8950872
64.5666929
66.6551495
63.0291
0.06774096
0.01414773
0.00348142
0.00157021
0.00027756
126,098
Table 2.43: ATR-198—Three Prior Years of Historical Speed Data for Four-Week
Period from 4/24 to 5/21
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Two Weeks Only
4/24/03 to 5/7/03)
58.3566585
7.974875457
59.68617252
53.50215018
64.14596062
64.77724975
67.47531993
64.0112577
0.08235751
0.016997252
0.00334568
0.00125463
0.000179233
33,476
A1-32
2003-2004
2004-2005
All Four Weeks
58.36815
7.113351
59.15368
54.12425
63.88717
64.57631
66.76706
67.6515
0.069259
0.014764
0.002848
0.000762
0.000241
74,777
All Four Weeks
57.66925
8.341811
59.09028
52.30496
63.86841
64.54546
66.55329
60.3224
0.066433
0.013537
0.002616
0.000626
0.000156
70,327
Table 2.44: ATR-198—Three Prior Years of Historical Speed Data for Eight-Week
Period from 5/22 to 7/16
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
58.53615019
7.455832262
59.62564398
53.52068533
64.15801023
64.79958945
67.60801339
65.1230543
0.084381465
0.018466418
0.003565026
0.001068818
0.00033099
145,020
2003-2004
58.52112
7.049374
59.22241
54.15645
64.00661
64.70073
67.33518
67.7559
0.078443
0.017542
0.002812
0.000956
0.000329
161,098
2004-2005
57.9589045
7.67596764
59.1035783
52.5418122
63.9018442
64.584433
66.7554296
62.139929
0.06955949
0.01384808
0.00259277
0.0007047
0.00021939
150,418
Table 2.45: ATR-198—Three Prior Years of Historical Speed Data for Eight-Week
Period from 7/17 to 8/13
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
58.72196906
7.408588582
59.8428351
53.73452111
64.27663522
64.90663824
67.93737364
65.6215174
0.092590372
0.020093003
0.003570905
0.000919375
0.000359755
75,051
A1-33
2003-2004
58.84599
7.251626
59.97714
54.10525
64.25896
64.87006
67.80652
67.1105
0.089368
0.019231
0.003674
0.000956
0.000246
73,214
2004-2005
57.57122
8.179326
58.84284
51.80835
63.86309
64.58224
66.87191
59.1148
0.070955
0.014983
0.003221
0.000987
0.000343
72,948
ATR-199
The historical speed data for ATR-199 are presented in Tables 2.46 through 2.53.
Table 2.46: ATR-199—Three Prior Years of Historical Speed Data for Six-Week
Period from 9/26 to 11/6
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
2003-2004
(All Six Weeks)
58.90707979
6.784359505
58.91393031
53.88343199
64.37905983
65.78481894
68.81013729
67.1223367
0.112970849
0.030334917
0.010424031
0.003123921
0.001233127
60,821
(All Six Weeks)
58.13940301
7.077248323
58.29614369
53.05802181
63.81268059
64.76808933
68.11770428
66.2296013
0.087863275
0.027140269
0.009372293
0.003024336
0.001417658
63,485
2004-2005
(Three Weeks Only
09/26/04 to 10/02/04,
10/10/04 to 10/16/04,
and
10/31/04 to 11/06/04)
59.4470086
6.1425485
59.4674055
55.2215039
64.2939658
64.995372
68.5377316
74.016409
0.09967009
0.02946961
0.00758153
0.00342596
0.00126887
31,524
Table 2.47: ATR-199—Three Prior Years of Historical Speed Data for Four-Week
Period from 11/7 to 12/4
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
58.34077
6.648154
58.32031
53.41253
63.83174
64.80081
68.1432
67.6881
0.089723
0.026534
0.008768
0.00288
0.001198
39,232
A1-34
2003-2004
57.71552
7.166249
57.94842
52.5116
63.50504
64.56496
67.68802
65.5821
0.079478
0.024646
0.009188
0.003135
0.001459
37,004
2004-2005
59.24235
6.207461
59.32768
55.16947
64.16109
64.87018
68.12581
73.5328
0.090846
0.025509
0.00665
0.00273
0.001117
40,299
Table 2.48: ATR-199—Three Prior Years of Historical Speed Data for Eight-Week
Period from 12/4 to 1/29
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
58.33950019
6.307339225
58.24452435
53.18106752
63.77177169
64.75244787
68.0962053
67.2861364
0.087378498
0.027016709
0.008633601
0.002863184
0.001365518
68,106
2003-2004
57.61727342
6.668731173
57.810578
52.34908752
63.30608223
64.39467683
67.20751488
65.868738
0.072197034
0.021920965
0.006718439
0.001990094
0.000897787
66,831
2004-2005
59.41032
5.874511
60.18853
55.09233
64.07568
64.63098
66.75363
74.8637
0.066773
0.018949
0.004356
0.001712
0.000683
80,586
Table 2.49: ATR-199—Two Prior Years of Historical Speed Data for Four-Week
Period from 1/30 to 2/26 [Speed Data for 2004-2005 Unreliable]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
58.03336
6.688672
58.1001
52.74322
63.65757
64.66677
67.96081
65.9485
0.08349
0.026934
0.009019
0.002718
0.001112
32,375
A1-35
2003-2004
57.32942
6.84888
57.63049
52.0179
63.11884
64.26351
66.92082
65.3745
0.06783
0.021418
0.006287
0.001911
0.000801
32,449
Table 2.50: ATR-199—Three Prior Years of Historical Speed Data for Eight-Week
Period from 2/27 to 4/23
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Four Weeks Only
42/27/03 to 3/26/03)
58.77478774
6.123310608
58.57185914
54.2857065
63.90565392
64.80245547
68.26698671
70.6470721
0.088986163
0.02931931
0.009459737
0.002937807
0.001410147
34,039
2003-2004
2004-2005
(All Eight Weeks)
58.30062
6.49931
58.3121
53.62205
63.64845
64.59909
67.66648
69.098
0.078913
0.024697
0.008955
0.00256
0.001219
73,815
(All Eight Weeks)
59.27763
6.158254
59.40541
55.17936
64.17134
64.86482
68.09728
73.7224
0.090253
0.025272
0.006332
0.002399
0.000795
70,435
Table 2.51: ATR-199—Three Prior Years of Historical Speed Data for Four-Week
Period from 4/24 to 5/21
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
58.6780023
6.389134495
58.54099217
54.09076348
63.9413775
64.85418857
68.27214953
69.6705709
0.092013056
0.02781511
0.010055678
0.003359892
0.001487952
41,668
A1-36
2003-2004
58.39212
6.806118
58.45958
53.82069
63.81217
64.72642
67.93139
68.872
0.085038
0.025274
0.008653
0.002958
0.001418
40,911
2004-2005
58.64458
7.322761
59.0854
55.01729
63.98065
64.71425
67.68437
70.684
0.080524
0.023669
0.006086
0.002198
0.000773
41,404
Table 2.52: ATR-199—Two Prior Years of Historical Speed Data for Eight-Week
Period from 5/22 to 7/16 [Speed Data for 2004-2005 Unreliable]
2002-2003
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
(All Eight Weeks)
58.67879668
6.07859794
58.54558136
54.20022569
63.85398291
64.74917929
67.93492164
70.4251221
0.085990744
0.024676085
0.007886627
0.002485282
0.001215027
90,533
2003-2004
(Four Weeks Only
6/18/04- to 7/15/04)
59.34205
5.761595
59.31992
55.19872
64.13725
64.84509
68.08156
74.4878
0.089058
0.025685
0.006642
0.002317
0.000794
45,319
Table 2.53: ATR-199—Two Prior Years of Historical Speed Data for Four-Week
Period from 7/17 to 8/13 [No Speed Data Available for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
58.82344193
6.032315854
58.64039441
54.41565315
63.97358378
64.85641762
68.18085267
70.7138272
0.091868097
0.026055402
0.008070433
0.002399318
0.001050941
50,431
A1-37
2003-2004
59.49479
5.715408
59.4708
55.2594
64.23362
64.92534
68.27571
75.0628
0.094603
0.026521
0.006754
0.002364
0.000878
44,417
ATR-222
The historical speed data for ATR-222 are presented in Tables 2.54 through 2.61.
Table 2.54: ATR-222—Three Prior Years of Historical Speed Data for Six-Week
Period from 9/26 to 11/6
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
62.38842361
6.752688486
62.34049097
56.87386281
68.29882291
69.59491273
72.96675284
63.9534127
0.277260583
0.084372716
0.026442855
0.006745504
0.002767693
83,463
2003-2004
62.38487803
6.903481823
62.44529338
56.92256101
68.28026384
69.48608956
72.6820967
64.1062155
0.286017328
0.078690517
0.025205277
0.007281524
0.002657578
83,911
2004-2005
61.88683
6.471429
61.91299
56.54965
67.61303
69.07918
71.93456
65.683
0.239111
0.068598
0.020531
0.004948
0.001887
82,656
Table 2.55: ATR-222—Three Prior Years of Historical Speed Data for Four-Week
Period from 11/7 to 12/4
2002-2003
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
(All Four Weeks)
62.43874
6.488777
62.37249
56.90373
68.27121
69.52955
72.76834
64.0773
0.279981
0.081307
0.024762
0.006223
0.002148
53,993
A1-38
2003-2004
(Two Weeks Only
11/7/03 to 11/20/03)
62.40633587
6.704449738
62.35696756
56.92298843
68.26481082
69.54820777
72.77477852
64.2786419
0.277194117
0.082398578
0.024018102
0.006982382
0.002909326
30,935
2004-2005
(All Four Weeks)
62.17078
7.000129
62.19346
56.57778
68.24501
69.59943
73.0288
63.0872
0.269793
0.085212
0.027083
0.007014
0.002903
47,188
Table 2.56: ATR-222—Three Prior Years of Historical Speed Data for Eight-Week
Period from 12/5 to 1/29
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
62.17346819
7.165836242
62.21499094
56.49026902
68.46862308
69.82097635
73.3094115
61.8315895
0.278243971
0.093381032
0.027839119
0.006521803
0.002384948
67,926
2003-2004
61.71381
7.444674
61.89128
56.06548
68.13353
69.57967
73.02907
61.7467
0.258341
0.085467
0.026923
0.007049
0.002911
65,967
2004-2005
60.22043
8.327492
60.76857
54.85187
67.14027
68.9243
72.00958
63.0452
0.209984
0.069852
0.020459
0.005316
0.002206
60,757
Table 2.57: ATR-222—Three Prior Years of Historical Speed Data for Four-Week
Period from 1/30 to 2/26
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
61.87020728
7.402840911
62.02945743
56.16333956
68.31956603
69.71009499
73.13155803
61.2431173
0.269363426
0.089575729
0.026387168
0.00679771
0.00241101
29,863
A1-39
2003-2004
60.50981
8.227774
61.12903
55.16492
67.35421
69.02619
72.07189
62.5695
0.220402
0.070878
0.020493
0.005123
0.001991
30,644
2004-2005
61.45784
7.65441
61.70776
55.87966
67.99588
69.50457
72.86562
61.8164
0.249287
0.083581
0.024988
0.006596
0.003001
33,656
Table 2.58: ATR-222—Three Prior Years of Historical Speed Data for Eight-Week
Period from 2/27 to 4/23
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Four Weeks Only
2/27/03 to 3/26/03)
61.7767266
7.39740459
61.9434643
56.2390053
68.1086675
69.5590464
72.9381388
62.611779
0.25716743
0.08479867
0.02557977
0.00640291
0.00245285
31,392
2003-2004
2004-2005
(All Eight Weeks)
61.84384
7.086399
62.00804
56.29909
67.99889
69.31803
72.39525
62.8049
0.263668
0.074151
0.023737
0.006525
0.002519
63,910
(All Eight Weeks)
61.52307
7.207842
61.76726
56.16089
67.6366
69.07725
71.95932
64.1666
0.241507
0.067975
0.022105
0.005987
0.002072
65,642
Table 2.59: ATR-222—Two Prior Years of Historical Speed Data for Four-Week
Period from 4/24 to 5/21 [No Speed Data Available for 2002-2003]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2003-2004
62.31703
6.577262
62.37226
56.97333
68.00445
69.22121
71.98748
65.5231
0.273461
0.067997
0.02272
0.006027
0.00235
48,943
A1-40
2004-2005
62.07343
6.454391
62.14766
56.81538
67.71138
69.05431
71.65522
66.3082
0.250951
0.06479
0.020113
0.00471
0.001707
46,288
Table 2.60: ATR-222—Three Prior Years of Historical Speed Data for Eight-Week
Period from 5/22 to 7/16
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
62.20504
6.540487
62.25911
56.89566
67.89203
69.17836
71.91917
65.7931
0.262415
0.068062
0.021005
0.005557
0.002156
141,444
2003-2004
61.94813
6.51917
62.02968
56.6364
67.67527
69.04878
71.69074
65.709
0.247388
0.065373
0.019912
0.004989
0.001775
134,093
2004-2005
61.68342
6.637649
61.79083
56.50265
67.33793
68.87944
71.51689
66.8588
0.225832
0.063654
0.018648
0.004858
0.001954
131,540
Table 2.61: ATR-222—Two Prior Years of Historical Speed Data for Four-Week
Period from 7/17 to 8/13 [No Speed Data Available for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
62.40169935
6.747885391
62.41339453
56.99910791
68.1949605
69.44638678
72.65161201
64.9182654
0.277652766
0.07788071
0.025307578
0.006779859
0.002337882
68,438
A1-41
2003-2004
61.99021
6.572807
62.04654
56.6807
67.685
69.08158
71.87392
65.8893
0.246128
0.067119
0.021442
0.005807
0.002267
68,371
Section 3: 4-Lane Divided Highway Speed Data
The historical speed data obtained from the five ATRs and one Tube that were located on
4-Lane Divided Highways are presented in this section of the report. Four of the five
ATRs and the Tube were located Within Enhanced Enforcement Zones, while the
remaining ATR was located Outside the Enhanced Enforcement Zones. The speed limit
remained unchanged—at 65 mph—at all these locations throughout the MSMP.
3.1. Historical Speed Data from ATRs Located Within Enhanced Enforcement Zones
The four ATRs located Within Enhanced Enforcement Zones on 4-Lane Divided
Highways were as follows; (1) ATR-172,on US-10, near Dilworth, in Clay County, (2)
ATR-187, on US-10, near Rice, in Benton County, (3) ATR-188, on US-52, North of
Rochester, in Olmstead County, and (4) ATR-197, on SR-60, West of SR-4, in
Watonwan County. For these four ATRs, there were historical data from the same time
periods that were used in the MSMP. In some cases, three years of historical speed data
were available; in others, one or two years of historical data were available.
ATR-172
For ATR-172, historical speed data is available from only one prior year (2004-2005).
These data are presented in Tables 3.1 through 3.8.
Table 3.1: ATR-172—Historical Speed Data for Six-Week Period from 9/26/04 to
11/6/04
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
66.49387
5.713767
67.00688
61.56234
71.67014
72.95295
74.23575
69.6296
0.691027
0.215098
0.020212
0.003642
0.00106598
649,180
A1-42
Table 3.2: ATR-172—Historical Speed Data for Four-Week Period from 11/7//04 to
12/4/04
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
66.560
5.7826
67.072
61.600
71.817
73.047
74.276
69.136
0.69543
0.22390
0.020579
0.0040054
0.0011892
395,218
Table 3.3: ATR-172— Historical Speed Data for Data for Eight-Week Period from
12/5/04 to 01/29/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
63.97516
7.696323
65.25155
57.87969
69.95869
71.75658
73.62814
60.3059
0.518704
0.146928
0.01335
0.002585
0.00093148
682,782
A1-43
Table 3.4: ATR-172—Historical Speed Data for Data for Four-Week Period from
01/30/05 to 2/26/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
65.908
6.0748
66.552
60.983
71.262
72.669
74.075
69.138
0.63731
0.19487
0.017116
0.0028115
0.00070081
363,866
Table 3.5: ATR-172—Historical Speed Data for Data for Eight-Week Period from
2/27/05 to 4/23/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
66.00667
6.061606
66.71468
61.04258
71.28844
72.6851
74.08175
69.165
0.658598
0.196126
0.017127
0.003298
0.001002
762,541
A1-44
Table 3.6: ATR-172—Historical Speed Data for Data for Four-Week Period from
4/24 to 5/21
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
66.532
5.5059
66.974
61.703
71.473
72.823
74.174
71.034
0.69274
0.20455
0.019402
0.0036614
0.0012265
440,270
Table 3.7: ATR-172—Historical Speed Data for Data for Eight-Week Period from
5/22/05 to 7/16
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
66.60365
5.424971
67.01931
61.72764
71.59686
72.90745
74.21804
70.6100
0.69584
0.210921
0.020168
0.00375
0.001072
989,403
A1-45
Table 3.8: ATR-172—Historical Speed Data for Data for Four-Week Period from
7/17/05 to 8/13/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
66.815
5.3188
67.171
61.928
71.844
73.081
74.318
70.392
0.71140
0.22451
0.022457
0.0040965
0.0011490
512,630
A1-46
ATR-187
The historical speed data for ATR-187 are presented in Tables 3.9 through 3.16.
Table 3.9: ATR-187—Three Prior Years of Historical Speed Data for Six-Week
Period from 9/26 to 11/6
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
2003-2004
(All Six Weeks)
68.89784244
6.459888708
68.84969889
63.60343227
74.36491221
75.78160814
78.88907431
66.4158041
0.810537789
0.407210415
0.112576294
0.032124895
0.005291823
815,598
(All Six Weeks)
69.38757
5.690815
69.74804
64.49782
74.32189
74.9726
78.07134
70.7798
0.83747
0.482092
0.097894
0.019924
0.003194
844,339
2004-2005
(Two Weeks Only
9/26/04 to 10/9/04)
69.67999
5.415989
69.99632
65.06719
74.38976
75.0851
78.16595
73.547
0.854771
0.499739
0.101381
0.020235
0.002942
302,502
Table 3.10: ATR-187—Three Prior Years of Historical Speed Data for Four-Week
Period from 11/7 to 12/4
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
69.251
5.6327
69.176
63.665
74.479
75.904
78.671
66.695
0.80817
0.43923
0.11633
0.025996
0.0040175
517,738
A1-47
2003-2004
69.180
5.5710
69.525
64.154
74.209
74.876
77.715
69.718
0.82785
0.46557
0.090675
0.015779
0.0021701
511,960
2004-2005
69.487
5.7139
69.981
64.853
74.357
74.982
77.966
71.905
0.84655
0.49866
0.098541
0.016705
0.0023389
495,957
Table 3.11: ATR-187—Two Prior Years of Historical Speed Data for Eight-Week
Period from 12/5 to 1/29 [No Speed Data Available for 2002-2003]
2003-2004
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
(All Eight Weeks)
70.81684
5.929378
71.20714
65.36807
76.58958
78.09773
79.60589
64.9639
0.870294
0.59462
0.2027
0.036934
0.004365
925,059
2004-2005
(Four Weeks Only
12/5/04 to 1/1/05)
69.074
5.7423
69.462
63.974
74.163
74.832
77.597
69.066
0.82240
0.46117
0.087435
0.015362
0.0021885
479,315
Table 3.12: ATR-187—One Prior Year of Historical Speed Data for Four-Week
Period from 1/30 to 2/26 [No Speed Data Available for 2003-2004 or 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
68.698
6.0222
68.744
63.028
74.200
75.101
78.295
64.747
0.78496
0.40436
0.10158
0.023302
0.0036578
425,936
A1-48
Table 3.13: ATR-187—Two Prior Years of Historical Speed Data for Eight-Week
Period from 2/27 to 4/23 [No Speed Data Available for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Four Weeks Only
1/30/03 to 2/26/03)
69.277
5.7534
69.139
64.164
74.466
75.917
78.727
68.495
0.82707
0.43198
0.11632
0.027353
0.0043404
449,493
2003-2004
(All Eight Weeks)
69.58608
5.180375
69.87404
65.05337
74.29877
74.92936
77.85833
73.6396
0.853875
0.490855
0.094399
0.016733
0.002248
975,193
Table 3.14: ATR-187—Two Prior Years of Historical Speed Data for Four-Week
Period from 4/24 to 5/21 [No Speed Data Available for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
69.323
5.5630
69.596
64.423
74.248
74.910
77.919
70.825
0.8352
0.47051
0.093233
0.019170
0.0032075
577,401
A1-49
2003-2004
69.577
5.1448
69.822
65.033
74.282
74.917
77.850
73.578
0.85238
0.48697
0.093504
0.017187
0.0025364
570,497
Table 3.15: ATR-187—Two Prior Years of Historical Speed Data for Eight-Week
Period from 5/22 to 7/16 [No Speed Data Available for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Four Weeks Only
5/22/03 to 6/19/03)
69.127
5.2523
69.264
64.129
74.050
74.739
77.394
70.566
0.82532
0.44388
0.081071
0.016169
0.0030748
661,184
2003-2004
(Four Weeks Only
5/22/03 to 6/19/03)
68.943
5.2891
69.116
63.807
73.980
74.684
77.179
69.34
0.81461
0.43242
0.077579
0.014296
0.0020744
639,210
Table 3.16: ATR-187—Two Prior Years of Historical Speed Data for Four-Week
Period from 7/17 to 8/13 [No Speed Data Available for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
69.839
5.3649
70.017
65.049
74.515
75.709
78.592
73.251
0.85344
0.50129
0.11230
0.025578
0.0054495
721,713
A1-50
2003-2004
69.65963
5.550044
69.87186
65.04295
74.45091
75.45432
78.30527
72.7288
0.853113
0.490712
0.107968
0.020278
0.003819
505,873
ATR-188
The historical speed data for ATR-188 are presented in Tables 3.17 to 3.24.
Table 3.17: ATR-188—Two Prior Years of Historical Speed Data for Six-Week
Period from 9/26 to 11/6 [No Speed Data Available for 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Two Weeks Only
9/26/02 to 10/9/02)
65.88014
7.760541
66.44702
59.95179
72.51142
73.85515
76.00429
59.5308
0.604485
0.243449
0.0574
0.020556
0.007364
383,098
2004-2005
(All Six Weeks)
64.55029
9.741072
65.99876
56.81517
72.98474
74.19811
76.43537
49.8121
0.556664
0.272994
0.066956
0.007891
0.001872
1,238,782
Table 3.18: ATR-188—Two Prior Years of Historical Speed Data for Four-Week
Period from 11/7 to 12/4 [No Speed Data Available for 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Two Weeks Only
11/14/02 to 11/27/02)
65.51142322
7.640590142
66.14375301
59.90497604
71.83980367
73.36773696
74.89567024
62.7859531
0.585952271
0.210205628
0.046585919
0.016508429
0.00696569
391,921
A1-51
2004-2005
(All Four Weeks)
65.9493
8.634053
66.89048
60.21132
73.31618
74.41351
76.79549
55.6849
0.620923
0.301103
0.073276
0.008457
0.001816
802,496
Table 3.19: ATR-188—Two Prior Years of Historical Speed Data for Eight-Week
Period from 12/5 to 1/29 [No Speed Data Available for 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Four Weeks Only
(12/5/02 to 1/1/03)
66.39996
9.697007
67.2555
58.03573
74.48654
76.4609
79.27585
46.0245
0.614927
0.360157
0.125949
0.037137
0.013582
758,292
2004-2005
(All Eight Weeks)
66.13985
8.311737
67.10001
60.35876
73.26395
74.36379
76.68531
56.9103
0.645999
0.298384
0.071077
0.008546
0.001832
1,457,212
Table 3.20: ATR-188—Two Prior Years of Historical Speed Data for Four-Week
Period from 1/30 to 2/26 [No Speed Data Available for 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
65.703
9.5075
66.502
57.375
73.994
75.565
78.768
47.558
0.58013
0.31344
0.10883
0.030765
0.010554
733,945
A1-52
2004-2005
67.000
8.0276
67.769
61.170
73.782
74.751
77.412
57.386
0.69222
0.34516
0.087166
0.010112
0.0021072
748,849
Table 3.21: ATR-188—Two Prior Years of Historical Speed Data for Eight-Week
Period from 2/27 to 4/23 [No Speed Data Available for 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Four Weeks Only
2/27/03 to 3/26/03)
66.576
9.0085
67.213
59.077
74.222
75.911
78.960
49.802
0.62699
0.34013
0.11495
0.032941
0.010801
778,838
2004-2005
(All Eight Weeks)
67.41025
7.964623
68.07361
61.58938
74.02384
74.94875
77.76501
57.9403
0.711364
0.367527
0.09723
0.011824
0.002287
1,554,599
Table 3.22: ATR-188—Two Prior Years of Historical Speed Data for Four-Week
Period from 4/24 to 5/21 [No Speed Data Available for 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
66.842
8.9142
67.395
59.826
74.305
76.090
79.092
50.778
0.64028
0.34739
0.11814
0.034888
0.011294
873,448
A1-53
2004-2005
67.304
7.1709
67.723
61.349
73.817
74.785
77.468
57.824
0.68299
0.34701
0.088919
0.010088
0.0019536
847,660
Table 3.23: ATR-188—Two Prior Years of Historical Speed Data for Eight-Week
Period from 5/22 to 7/16 [Speed Data Unreliable for 2002-2003]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2003-2004
66.52114
7.098353
66.93512
60.77017
73.17391
74.26936
76.4021
58.5418
0.629519
0.294867
0.066652
0.007271
0.001754
1,700,876
2004-2005
67.22246
6.894435
67.58046
61.3919
73.59516
74.61235
77.14375
59.4499
0.684806
0.32672
0.080945
0.00877
0.001713
1,764,460
Table 3.24: ATR-188—Two Prior Years of Historical Speed Data for Four-Week
Period from 7/17 to 8/13 [No Speed Data Available for 2002-2003]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2003-2004
66.941
6.9640
67.329
61.167
73.398
74.439
76.765
59.222
0.66280
0.31324
0.073030
0.0077847
0.0017183
879,926
A1-54
2004-2005
67.415
6.8332
67.753
61.549
73.734
74.735
77.381
59.656
0.70035
0.33652
0.086779
0.0095296
0.0017330
879,997
ATR-197
The historical speed data for ATR-197 are presented in Tables 3.25 through 3.31.
Table 3.25: ATR-197—Two Prior Years of Historical Speed Data for Six-Week
Period from 9/26 to 11/6 [No Speed Data Available for 2002-2003]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2003-2004
(Two Weeks Only
9/26/03 to 10/9/03)
65.23869121
7.959496729
66.21726011
60.09906516
71.83967149
73.18925479
74.53883809
63.3298615
0.590695165
0.218157019
0.032914656
0.009157948
0.002772865
66,718
2004-2005
(All Six Weeks)
66.07991
6.563683
66.65845
60.97361
71.88694
73.17294
74.45894
66.3007
0.637298
0.223364
0.028964
0.006798
0.001537
205,637
ATR-197—11/7 to 12/4 Time Period
Please note, no speed data were available for ATR-197 during the 11/7 to 12/4 time
period in any of the three years prior to the MSMP.
A1-55
Table 3.26: ATR-197—One Prior Year of Historical Speed Data for Eight-Week
Period from 12/5 to 1/29 [No Speed Data Available for 2003-2004 and 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
65.27284
7.547038
66.05917
60.2842
71.59681
72.9742
74.3516
65.2593
0.57849
0.207965
0.026463
0.006769
0.002202
228,851
Table 3.27: ATR-197—Two Prior Years of Historical Speed Data for Four-Week
Period from 1/30 to 2/26 [No Speed Data Available for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
64.383
7.0457
65.182
58.468
70.312
72.094
73.876
62.495
0.51289
0.15876
0.018478
0.0040890
0.0013496
100,771
A1-56
2003-2004
62.989
9.4362
64.550
56.315
70.349
72.119
73.889
52.398
0.47408
0.15985
0.018612
0.0042929
0.0013820
102,029
Table 3.28: ATR-197—Two Prior Years of Historical Speed Data for Four-Week
Period from 2/27 to 4/23 [No Speed Data Available for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Four Weeks Only
2/27/03 to 3/26/03)
65.614
5.6698
65.559
60.914
71.087
72.646
74.205
70.764
0.53964
0.18487
0.024498
0.0057580
0.0012898
106,990
2003-2004
(All Eight Weeks)
65.8514
6.780287
66.50259
60.59989
71.91613
73.19168
74.46722
64.5008
0.618101
0.22511
0.029116
0.007034
0.002141
245,675
Table 3.29: ATR-197—Two Prior Years of Historical Speed Data for Four-Week
Period from 4/24 to 5/21 [No Speed Data Available for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
66.050
6.5474
66.596
60.718
72.089
73.332
74.575
64.075
0.62475
0.23400
0.032909
0.0073590
0.0020916
130,998
A1-57
2003-2004
66.072
6.5299
66.646
60.655
72.101
73.334
74.567
63.714
0.62990
0.23520
0.032460
0.0078464
0.0024453
131,271
Table 3.30: ATR-197—Two Prior Years of Historical Speed Data for Four-Week
Period from 5/22 to 7/16 [No Speed Data Available for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
65.5938
6.617139
66.21317
60.23512
71.8639
73.20325
74.54259
63.3001
0.589836
0.219582
0.032924
0.007806
0.001952
319,643
2003-2004
66.30204
6.307486
66.86082
60.75739
72.29424
73.4536
74.61295
63.1382
0.648818
0.248945
0.033308
0.007455
0.001854
284,770
Table 3.31: ATR-197—Two Prior Years of Historical Speed Data for Four-Week
Period from 7/17 to 8/13 [No Speed Data Available for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
65.878
6.8932
66.569
60.296
72.309
73.527
74.744
61.239
0.61669
0.24480
0.039498
0.0095326
0.0023270
146,969
A1-58
2003-2004
66.600
6.3537
67.153
61.053
72.528
73.626
74.723
63.383
0.67753
0.26517
0.037393
0.0085147
0.0021700
151,150
3.2. Historical Speed Data from Tube Located Within an Enhanced Enforcement Zone
There was one Tube located Within an Enhanced Enforcement Zones on a 4-Lane
Divided Highway. It was Tube 05, on MN-60, near Lake Crystal, in Blue Earth County.
Tube 05 only collected speed data from the eastbound lanes of MN-60. Seven days of
Pre-MSMP speed data were collected from this Tube during August 2005. These speed
data are presented in Table 3.32.
Table 3.32: Tube 05—Pre-MSMP Speed Data (Eastbound Only) for One-Week
Period from 8/22/05 to 8/29/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
76.875096
6.0283774
76.901206
71.34584
82.159221
83.61137
90.209539
66.40194
0.9729355
0.9166179
0.6691224
0.2243457
0.052187
32,441
A1-59
3.3. Historical Speed Data from ATR Located Outside Enhanced Enforcement Zones
There was one ATR located on a 4-Lane Divide Highway Outside the Enhanced
Enforcement Zones. It was ATR-353, on MNTH-169 near Jordan in Scott County. The
historical speed data for this ATR are presented in Tables 4.33 through 4.40.
Table 3.33: ATR-353—Two Prior Years of Historical Speed Data for Six-Week
Period from 9/26 to 11/6 [No Speed Data Available for 2002-2003]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2003-2004
68.0053066
6.27768366
68.4754547
62.8751564
73.4612406
74.2190849
74.9769292
66.546581
0.77729648
0.37836094
0.04847787
0.00695509
0.0011228
952,971
2004-2005
67.9698
6.518586
68.49053
63.00731
73.44904
74.20816
74.96728
66.9676
0.784025
0.377174
0.047845
0.006555
0.000978
980,861
Table 3.34: ATR-353—Two Prior Years of Historical Speed Data for Four-Week
Period from 11/7 to 12/4 [No Speed Data Available for 2002-2003]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2003-2004
67.637996
6.2076053
68.172187
62.34425
73.258212
74.056755
74.855298
65.04774
0.7533673
0.3540098
0.0409396
0.0052716
0.0007842
578,950
2004-2005
68.36073
5.711711
68.72126
63.42388
73.5402
74.25617
74.97214
68.9507
0.799065
0.397232
0.048055
0.006255
0.000945
619,067
Table 3.35: ATR-353—Two Prior Years of Historical Speed Data for Eight-Week
Period from 12/05 to 1/29 [No Speed Data Available for 2002-2003]
A1-60
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2003-2004
67.446269
6.3592905
68.064262
62.164986
73.158928
73.974156
74.789384
64.61062
0.7473505
0.3437451
0.0370824
0.00466
0.0007342
1,066,517
2004-2005
67.68885
6.330969
68.27701
62.42994
73.31483
74.09088
74.86692
65.0549
0.759477
0.363572
0.041426
0.005271
0.000817
1,091,536
Table 3.36: ATR-353—Two Prior Years of Historical Speed Data for Four-Week
Period from 1/30 to 2/26 [No Speed Data Available for 2002-2003]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2003-2004
66.91672
6.961625
67.79227
61.37391
73.06803
73.92134
74.77465
61.2374
0.715297
0.329773
0.036795
0.004662
0.000679
519,524
A1-61
2004-2005
68.18838
6.168288
68.71178
63.23826
73.54424
74.25987
74.9755
67.6695
0.79496
0.39763
0.048289
0.006074
0.000944
565,973
Table 3.37: ATR-353—Two Prior Years of Historical Speed Data for Eight-Week
Period from 2/27 to 4/23 [No Speed Data Available for 2002-2003]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2003-2004
68.31456
5.990657
68.74261
63.47233
73.55015
74.26443
74.97872
68.8457
0.802084
0.398511
0.04851
0.006085
0.000868
1,161,608
2004-2005
68.30579
5.956492
68.76101
63.40898
73.55403
74.26196
74.96988
68.5679
0.800468
0.401017
0.047873
0.005946
0.00088
1,180,206
Table 3.38: ATR-353—Three Prior Years of Historical Speed Data for Eight-Week
Period from 4/24 to 5/21
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
68.16125952
6.2361249
68.60777283
63.22461616
73.51785427
74.25951716
75.00919383
67.8014943
0.792410157
0.387159923
0.050079554
0.006814685
0.000974701
608,392
A1-62
2003-2004
68.24015
6.103669
68.69873
63.29941
73.54261
74.26286
74.98311
68.0891
0.795809
0.39593
0.048828
0.006337
0.000945
627,432
2004-2005
68.29125
6.032863
68.73218
63.37672
73.55047
74.26419
74.9779
68.4572
0.798115
0.398731
0.048452
0.00614
0.000935
636,670
Table 3.39: ATR-353—Three Prior Years of Historical Speed Data for Eight-Week
Period from 5/22 to 7/16
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
68.0544364
6.18923791
68.5009207
63.0897329
73.4265865
74.1797033
74.9328202
67.647339
0.78609888
0.37749368
0.04553988
0.00607598
0.0009459
1,250,662
2003-2004
68.02412
5.871711
68.40487
63.07749
73.32338
74.08995
74.85652
68.2302
0.784385
0.36677
0.040641
0.005266
0.000839
1,100,110
2004-2005
68.13813
6.100104
68.58462
63.17304
73.46749
74.20357
74.93965
67.8776
0.78989
0.385538
0.045901
0.006005
0.000938
1,293,813
Table 3.40: ATR-353—Three Prior Years of Historical Speed Data for Four-Week
Period from 7/17to 8/13
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
68.21131707
6.451063945
68.71099927
63.30946373
73.58240327
74.30698018
75.24230113
67.7531462
0.795939627
0.397206556
0.052177622
0.007241352
0.001087737
651,812
A1-63
2003-2004
68.1104
6.327548
68.59878
63.24189
73.466
74.20009
74.93419
68.0073
0.792601
0.386072
0.045518
0.005854
0.000931
678,857
2004-2005
68.25739
6.285461
68.73941
63.38244
73.57493
74.29233
75.07734
68.1801
0.799138
0.399158
0.050679
0.006805
0.001041
682,852
Section 4: Rural Freeway Speed Data
The historical speed data obtained from the five ATRs and two Tubes that were located
on Rural Freeways are presented in this section of the report.
The two Tubes and four of the five ATRs were located Within Enhanced Enforcement
Zones, while the remaining ATR was located Outside the Enhanced Enforcement Zones.
During the MSMP, the speed limit remained unchanged at 70 mph at the locations of the
five ATRs and the two Tubes.
4.1. Historical Speed Data from ATRs Located Within Enhanced Enforcement Zones
The four ATRs located Within Enhanced Enforcement Zones on Rural Freeways were as
follows: (1) ATR-175, on I-94, near Saulk Centre in Stearns County, (2) ATR-191, on I35, near Wyoming, in Chisago County, (3) ATR-208, on I-35, near Owatanna in Steele
County, and (4) ATR-227, on I-90, near Alden in Freeborn County. For these four
ATRs, there are historical data from the same time periods that were used in the MSMP.
In some cases, three years of historical speed data are available; in others, one or two
years of historical data are available.
A1-64
ATR-175
The available historical speed data for ATR-175 are presented in Tables 4.1 through 4.8.
Table 4.1.: ATR-175—Three Prior Years of Historical Speed Data for Six-Week
Period from 9/26 to 11/6
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Two Weeks Only
9/26/02 to 11/6/02
70.86291744
7.307424416
71.09150749
63.8019649
77.97733399
79.34718723
82.22883352
55.0334616
0.821337852
0.567394198
0.258673466
0.076172164
0.01745947
311,006
2003-2004
(Four Weeks Only
10/10/03 to 11/6/02)
73.0090375
6.82435646
73.5373508
66.6722916
79.0351616
79.8639499
82.6746643
60.10246
0.89637559
0.75771678
0.39343741
0.09179223
0.01366611
616,708
2004-2005
(All Six Weeks)
73.32701
6.070776
73.5641
67.50634
78.9164
79.7367
82.34786
63.9794
0.924156
0.77622
0.388717
0.083951
0.011649
925,398
Table 4.2.: ATR-175—Three Prior Years of Historical Speed Data for Four-Week
Period from 11/7 to 12/4
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Three Weeks Only
11/07/02 to 20/11/02)
71.00726993
7.52713863
71.24309458
63.81030756
78.17668892
79.51959937
82.63114067
54.1668513
0.821829163
0.576673345
0.268276276
0.082113453
0.021087729
273,524
A1-65
2003-2004
2004-2005
(All Four Weeks)
72.6634
6.704558
73.19956
66.42695
78.73264
79.60608
82.02744
60.1508
0.893027
0.742261
0.363676
0.07745
0.009754
552,888
(All Four Weeks)
73.125
6.0863
73.417
67.218
78.797
79.632
82.065
63.204
0.91787
0.76491
0.37729
0.078001
0.010190
571,648
Table 4.3: ATR-175—Three Prior Years of Historical Speed Data for Eight-Week
Period from 12/5 to 1/29
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
71.07513416
8.129937673
71.29723079
63.27889215
78.64813741
80.02597825
83.51245174
51.4202134
0.808775691
0.575699991
0.283924653
0.100372558
0.028666864
986,156
2003-2004
72.64084
6.256236
73.06038
66.68527
78.53514
79.43884
81.55615
61.9854
0.904083
0.743626
0.345593
0.068952
0.008058
982,973
2004-2005
72.14705
6.5463
72.71506
65.96347
78.35168
79.31423
81.26161
59.6083
0.883653
0.709007
0.324105
0.064377
0.007397
964,438
Table 4.4: ATR-175—Three Prior Years of Historical Speed Data for Four-Week
Period from 1/30 to 2/26
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
70.607
8.4528
70.965
62.586
78.442
79.866
83.319
51.189
0.78996
0.55482
0.27084
0.095313
0.027046
458,028
A1-66
2003-2004
71.491
7.3845
72.411
65.195
78.161
79.180
80.926
57.258
0.85686
0.68148
0.30517
0.059724
0.0072406
463,495
2004-2005
72.974
5.7627
73.205
67.163
78.619
79.495
81.679
63.628
0.92169
0.75596
0.35662
0.071188
0.0080839
489,987
Table 4.5: ATR-175—Three Prior Years of Historical Speed Data for Eight-Week
Period from 2/27 to 4/23
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Four Weeks Only
2/27/03 to 3/26/03)
70.875
8.0720
71.257
62.979
78.433
79.694
82.985
50.75
0.79863
0.57185
0.28614
0.087872
0.024438
495,780
2003-2004
2004-2005
(All Eight Weeks)
73.30657
6.21204
73.57907
67.42856
78.9435
79.76189
82.42839
63.5385
0.92109
0.774728
0.39093
0.085452
0.012457
1,093,228
(All Eight Weeks)
73.17625
6.245244
73.49373
67.39057
78.84544
79.67057
82.153
63.5764
0.922068
0.771334
0.383018
0.080038
0.010279
1,077,686
Table 4.6: ATR-175—Three Prior Years of Historical Speed Data for Four-Week
Period from 4/24 to 5/21
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
70.770
7.3632
71.134
63.259
78.026
79.308
82.029
53.001
0.80439
0.56803
0.26800
0.073032
0.016279
599,377
A1-67
2003-2004
73.363
6.1670
73.615
67.493
78.981
79.798
82.500
63.687
0.92241
0.77717
0.39380
0.087627
0.012388
602,442
2004-2005
73.246
6.1052
73.495
67.452
78.857
79.688
82.228
63.955
0.92322
0.77391
0.38204
0.081198
0.011196
607,204
Table 4.7: ATR-175—Three Prior Years of Historical Speed Data for Eight-Week
Period from 5/22 to 7/16
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
71.03253438
7.574996755
71.38147628
63.44542544
78.3508079
79.57007074
82.5670998
51.8378513
0.810886967
0.581161926
0.287411221
0.082369295
0.019322866
1,409,263
2003-2004
73.248
6.097405
73.53069
67.50286
78.85757
79.68241
82.18781
64.1904
0.921026
0.779137
0.383836
0.080749
0.010476
1,388,157
2004-2005
73.17893
6.262706
73.50612
67.43798
78.85745
79.6914
82.21141
63.8684
0.917898
0.778648
0.381275
0.081498
0.010281
1,429,654
Table 4.8: ATR-175—Two Prior Years of Historical Speed Data for Four-Week
Period from 7/17 to 8/13 [No Speed Data Available for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
71.510
7.7886
71.726
63.642
78.908
80.236
83.525
49.879
0.81719
0.59697
0.31607
0.10358
0.027574
750,013
A1-68
2003-2004
73.682
6.1192
73.932
68.058
79.178
79.956
82.795
65.215
0.92833
0.80026
0.41846
0.097193
0.012779
747,885
ATR-191
The available historical speed data for ATR-191 are presented in Tables 4.9 through 4.16.
Table 4.9: ATR-191—Three Prior Years of Historical Speed Data for Six-Week
Period from 9/26 to 11/6
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
72.0640404
7.913532134
72.4156467
64.59562802
79.5203852
81.32576175
83.63626004
49.8710765
84.1112046
0.639415457
0.350847892
0.128689953
0.020488185
1,863,269
2003-2004
71.70128
8.98837
71.93021
62.94585
80.30585
82.36178
84.4177
44.9507
79.9712
0.597311
0.345237
0.157438
0.035838
1,943,586
2004-2005
72.64986
7.407856
73.30518
65.54779
79.30017
80.40926
83.16568
51.5731
87.1855
0.672368
0.411614
0.107424
0.016726
1,905,909
Table 4.10: ATR-191—Three Prior Years of Historical Speed Data for Four-Week
Period from 11/7 to 12/4
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
2003-2004
(All Four Weeks)
(All Four
Weeks)
71.591
9.1824
71.893
62.692
80.232
82.365
84.497
44.605
0.79441
0.59439
0.34506
0.15544
0.038213
1,179,953
72.432
7.4922
72.585
65.348
79.579
81.404
83.650
51.756
0.86451
0.65629
0.35402
0.13127
0.019930
1,180,191
A1-69
2004-2005
(Two Weeks Only
11/21/04 to 12/4/04)
73.70661
7.628708
74.10812
66.04571
79.89723
82.13405
84.58293
52.5467
0.889325
0.701296
0.456298
0.143572
0.041484
575251
Table 4.11: ATR-191—Three Prior Years of Historical Speed Data for Eight-Week
Period from 12/5 to 1/29
2002-2003
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
(All Eight Weeks)
71.84316
7.764156
72.21538
64.09216
79.33346
81.01331
83.42204
49.6223
0.827904
0.628629
0.33832
0.121034
0.017245
2,139,130
2003-2004
(Four Weeks Only
12/05/03 to 1/01/04)
71.18233
8.912604
71.53843
62.65855
79.41716
81.46582
84.10677
46.973
0.793566
0.580614
0.318613
0.127752
0.033089
1,126,214
2004-2005
(All Eight Weeks)
71.61241
7.996446
72.3749
63.97789
78.90369
79.77624
82.57971
47.621
0.825689
0.614266
0.373696
0.087178
0.01512
2,086,191
Table 4.12: ATR-191—Two Prior Years of Historical Speed Data for Four-Week
Period from 1/30 to 2/26 [Speed Data for 2003-2004 Unreliable & Incomplete]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
71.586
8.2532
71.997
64.115
79.293
81.032
83.484
50.116
0.82986
0.61585
0.32575
0.12103
0.019102
1,031,371
A1-70
2004-2005
73.133
7.4018
73.614
65.745
79.655
81.409
83.834
50.957
0.88054
0.67546
0.43274
0.12907
0.025940
1,096,259
Table 4.13: ATR-191—Three Prior Years of Historical Speed Data for Eight-Week
Period from 2/27 to 4/23
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Four Weeks Only
1/30/03 to 3/26/03)
71.932
8.5533
72.281
63.391
79.994
82.074
84.158
46.04
0.81116
0.61998
0.35694
0.14977
0.029783
1,067,581
2003-2004
2004-2005
(All Eight Weeks)
72.34571
6.847429
72.6428
66.10553
78.5966
79.56561
82.24624
58.2702
0.897026
0.68434
0.335581
0.077586
0.016181
2,279,562
(All Eight Weeks)s
73.91781
6.672205
74.22176
67.34264
79.68112
81.36453
83.68286
59.7701
0.928908
0.760491
0.451981
0.129429
0.021593
2,324,100
Table 4.14: ATR-191—Two Prior Years of Historical Speed Data for Four-Week
Period from 4/24 to 5/21 [No Speed Data Available for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
71.791
8.5502
72.116
62.985
79.913
82.016
84.187
45.232
0.79780
0.60914
0.35128
0.14642
0.031272
1,245,084
A1-71
2003-2004
72.900
7.0470
73.005
66.576
78.833
79.749
82.920
59.563
0.91356
0.71190
0.35929
0.086314
0.024124
1,097,578
Table 4.15: ATR-191—Two Prior Years of Historical Speed Data for Eight-Week
Period from 5/22 to 7/16 [Speed Data for 2004-2005 Unreliable]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
70.92633
10.02696
71.69512
62.15574
79.84951
81.94522
84.14229
44.3155
0.778458
0.584783
0.334702
0.144268
0.030481
2,720,508
2003-2004
73.1274
7.470621
73.83552
66.93009
79.221
79.99237
82.89671
59.0748
0.911846
0.751631
0.423604
0.099505
0.014054
2,722,002
Table 4.16: ATR-191—Two Prior Years of Historical Speed Data for Eight-Week
Period from 7/17 to 8/13 [No Speed Data Available for 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
71.575
9.4146
71.966
62.802
80.472
82.422
84.371
44.221
0.79578
0.59705
0.35023
0.16211
0.033878
1,472,176
A1-72
2004-2005
72.595
8.0554
73.363
66.609
79.172
80.112
82.937
57.138
0.91067
0.72209
0.39185
0.10198
0.013480
1,588,824
ATR-208
The available historical speed data for ATR-208 are presented in Tables 4.17 through
4.24.
Table 4.17: ATR-208—Three Prior Years of Historical Speed Data for Six-Week
Period from 9/26 to 11/6
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
71.8120783
6.71241412
71.9428504
65.3972139
78.5007204
79.7637883
82.6334117
56.686679
0.86860946
0.63435957
0.28858006
0.09064929
0.0134694
1,137,913
2003-2004
72.5803
6.143445
72.76767
66.70285
78.48087
79.54416
82.07988
62.5982
0.911461
0.730997
0.313684
0.078565
0.009896
1,364,634
2004-2005
72.67636
5.552448
72.72781
67.08902
78.18797
79.27938
81.49568
65.5346
0.925461
0.744847
0.296049
0.066986
0.010202
1,244,416
Table 4.18: ATR-208—Three Prior Years of Historical Speed Data for Four-Week
Period from 11/7 to 12/4
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
72.009
6.4348
72.130
65.706
78.492
79.702
82.473
57.879
0.88242
0.65264
0.29436
0.087662
0.011525
816,131
A1-73
2003-2004
72.605
5.8604
72.925
68.508
77.853
79.004
80.682
70.825
0.92392
0.81855
0.27395
0.056722
0.0074715
774,274
2004-2005
72.777
5.6361
72.868
67.109
78.356
79.368
81.592
64.776
0.92455
0.74777
0.31580
0.068802
0.0097651
867,067
Table 4.19: ATR-208—Two Prior Years of Historical Speed Data for Eight-Week
Period from 12/5 to 1/29 [No Speed Data Available for 2003-2004]
2002-2003
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
(All Eight Weeks)
71.27247
6.781088
71.60967
65.10137
77.92265
79.21243
81.64721
57.9222
0.854917
0.612381
0.2633
0.069469
0.010372
1,474,945
2004-2005
(Four Weeks Only
1/2 to1/29)
70.733
6.5235
71.469
65.066
76.753
78.216
79.678
63.413
0.85306
0.62072
0.20992
0.039005
0.0047875
684,497
Table 4.20: ATR-208—Three Prior Years of Historical Speed Data for Four-Week
Period from 1/30 to 2/26
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
70.552
7.1277
71.119
63.546
77.520
78.859
80.773
56.348
0.81348
0.57377
0.24415
0.057375
0.0096749
677,731
A1-74
2003-2004
70.805
7.352
71.800
64.383
77.482
78.768
80.234
59.175
0.83849
0.64264
0.24651
0.052106
0.0070348
695,120
2004-2005
71.841
6.4247
72.334
66.169
77.757
78.932
80.482
63.539
0.89463
0.70374
0.26726
0.054585
0.0070647
750,204
Table 4.21: ATR-208—Three Prior Years of Historical Speed Data for Eight-Week
Period from 2/27 to 4/23
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
(Four Weeks Only
2/27/02 to 3/26/02)
71.481
6.4840
71.748
65.201
77.995
79.208
81.537
57.672
0.85957
0.62178
0.27347
0.067358
0.010895
756,018
2003-2004
(Four Weeks Only
2/27/02 to 3/26/02)
72.462
6.4087
72.828
66.719
78.316
79.308
81.351
63.166
0.90859
0.73814
0.31704
0.065141
0.0091125
814,484
2004-2005
(All Eight Weeks)
72.131949
6.6168477
72.581636
66.622398
77.980555
79.080095
80.812645
64.3148
0.9081487
0.7289428
0.2855365
0.0581686
0.0079092
1,653,400
Table 4.22: ATR-208—Three Prior Years of Historical Speed Data for Four-Week
Period from 4/24 to 5/21
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
72.604
5.6704
72.755
66.828
78.256
79.300
81.446
64.15
0.91441
0.73827
0.30579
0.066520
0.0094010
834,925
A1-75
2003-2004
72.700
5.8686
72.861
66.789
78.450
79.463
81.874
63.196
0.91103
0.74050
0.32017
0.073534
0.010734
875,336
2004-2005
72.490
5.6419
72.637
66.853
78.064
79.166
81.131
65.074
0.91757
0.73530
0.28907
0.062131
0.0085217
858,281
Table 4.23: ATR-208—Two Prior Years of Historical Speed Data for Eight-Week
Period from 5/22 to 7/16 [Speed Data for 2004-2005 Unreliable]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
71.24607
7.953791
72.53984
64.72107
78.30026
79.34539
81.58856
56.1673
0.846996
0.698335
0.307888
0.068683
0.009878
1,866,139
2003-2004
72.45278
5.99313
72.68982
66.6997
78.19688
79.26357
81.37428
63.8433
0.910235
0.733042
0.29985
0.065481
0.009158
1,906,622
Table 4.24: ATR-208—Two Prior Years of Historical Speed Data for Eight-Week
Period from 7/17 to 8/13 [Speed Data for 2004-2005 Unreliable]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
72.900
5.9449
73.025
67.144
78.578
79.557
82.070
64.06
0.92031
0.75632
0.33268
0.077361
0.011275
1,034,903
A1-76
2003-2004
72.942
5.6034
72.986
67.442
78.430
79.438
81.789
65.953
0.92953
0.76671
0.32010
0.072124
0.010282
987,998
ATR-227
The available historical speed data for ATR-227 are presented in Tables 4.25 through
4.32.
Table 4.25: ATR-227—Three Prior Years of Historical Speed Data for Six-Week
Period from 9/26 to 11/6
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Mean (mph)
2002-2003
(Four Weeks Only
10/10/02 to 11/6/02)
67.487
9.4726
68.852
57.450
75.645
77.827
80.025
45.700
0.69893
0.44071
0.16477
0.050208
0.0080683
272,425
2003-2004
2004-2005
(All Six Weeks)
69.73678
8.848341
70.90413
63.32649
77.10943
78.40747
79.70551
56.9775
0.812384
0.559323
0.231254
0.038656
0.007183
426,578
(All Six Weeks)
71.66066
6.464617
72.36121
65.36898
77.91033
78.87429
79.83825
58.7236
0.863696
0.678105
0.300957
0.04161
0.00719
403,340
Table 4.26: ATR-227—Three Prior Years of Historical Speed Data for Four-Week
Period from 11/7 to 12/4
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Mean (mph)
2002-2003
66.765
13.176
69.509
58.426
76.485
78.373
80.749
42.137
0.72511
0.47549
0.18932
0.056910
0.010801
257,564
A1-77
2003-2004
71.808
6.2760
72.376
66.050
77.767
78.786
79.805
62.298
0.89146
0.69397
0.28578
0.040439
0.0064916
253,865
2004-2005
71.926
6.4510
72.567
66.083
77.883
78.829
79.776
61.903
0.88908
0.70862
0.30229
0.038144
0.0064624
263,370
Table 4.27: ATR-227—Two Prior Years of Historical Speed Data for Eight-Week
Period from 12/5 to 1/29 [Speed Data for 2002-2003 Unreliable]
2003-2004
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Mean (mph)
(All Eight Weeks)
71.49464
6.618762
72.19077
65.86762
77.5866
78.65471
79.72281
62.2864
0.886004
0.67852
0.271084
0.037024
0.005983
442,926
2004-2005
(Four Weeks Only
1/2/05 to 1/29/05)
69.949
7.3312
70.886
64.404
76.206
77.692
79.178
64.380
0.83711
0.56667
0.19059
0.022342
0.0032767
196,845
Table 4.28: ATR-227—Two Prior Years of Historical Speed Data for Four-Week
Period from 1/30 to 2/26 [Speed Data for 2002-2003 Unreliable]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Mean (mph)
2003-2004
70.340
7.3174
71.386
64.059
77.003
78.268
79.533
60.029
0.83149
0.60386
0.22916
0.031526
0.0055309
204,308
A1-78
2004-2005
71.230
6.4345
71.909
65.921
77.045
78.239
79.434
65.175
0.89214
0.66330
0.23558
0.026302
0.0040567
216,677
Table 4.29: ATR-227—Two Prior Years of Historical Speed Data for Eight-Week
Period from 2/27 to 4/23 [Speed Data for 2002-2003 Unreliable]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2003-2004
71.69621
6.461195
72.36373
65.69619
77.8005
78.78714
79.77378
60.6064
0.876437
0.686568
0.29192
0.038536
0.006444
499,040
2004-2005
71.29863
6.769576
72.03413
65.70197
77.35623
78.46593
79.57562
62.6975
0.87985
0.667233
0.256165
0.030879
0.005069
475,798
Table 4.30: ATR-227—Three Prior Years of Historical Speed Data for Four-Week
Period from 4/24 to 5/21
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
66.119
8.3981
67.252
57.120
73.784
74.878
77.964
50.323
0.64510
0.32297
0.094423
0.019493
0.0039563
266,662
A1-79
2003-2004
71.733
6.1970
72.354
65.458
77.896
78.866
79.835
59.193
0.86728
0.67855
0.29926
0.041520
0.0071887
256,095
2004-2005
71.187
6.4384
71.872
65.248
77.332
78.464
79.596
60.946
0.86055
0.64776
0.25300
0.032148
0.0053480
257,096
Table 4.31: ATR-227—Three Prior Years of Historical Speed Data for Eight-Week
Period from 5/22 to 6/18
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
2003-2004
(All Eight Weeks)
66.79183691
8.190822179
67.76366285
57.79169692
74.33269458
75.9547767
78.67827492
49.1191052
0.671984095
0.360831642
0.117528499
0.025734791
0.004710997
657,398
(All Eight Weeks)
72.07203
5.997542
72.59549
65.9678
78.03363
78.96099
79.88836
0.607417
0.885704
0.701245
0.313563
0.043981
0.007213
631,893
2004-2005
(Four Weeks Only
6/18/05 to 7/1605)
72.119
6.1103
72.576
66.426
77.892
78.867
79.842
63.405
0.90413
0.71428
0.29829
0.041886
0.0068519
339,613
Table 4.32: ATR-227—Three Prior Years of Historical Speed Data for Four-Week
Period from 7/17 to 8/13
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
64.943
13.119
67.856
56.174
74.368
75.956
78.624
43.439
0.67085
0.37177
0.11792
0.024206
0.0046297
380,153
A1-80
2003-2004
72.283
6.0573
72.792
66.134
78.220
79.108
79.996
60.658
0.89010
0.71330
0.33137
0.049753
0.0078707
355,495
2004-2005
72.084
6.2918
72.575
66.269
77.969
78.940
79.911
62.371
0.89782
0.70934
0.30284
0.045420
0.0077773
363,495
4.2. Historical Speed Data from Tube Located Within an Enhanced Enforcement Zones
There were two Tube locations Within Enhanced Enforcement Zones on Rural Freeways.
They were: (1) Tube 06, located on I-94, near Fergus Falls in Otter Tail County, and
Tube 07, located on I-35, near Cloquet in Carlton County. Tube 06 only collected speed
data from the Eastbound lanes of I-94; while Tube collected speed data from all lanes on
I-35. Seven days of Pre-MSMP speed data were collected from each Tube during August
2005. These speed data are presented in Tables 4.33 and 4.34.
Table 4.33: Tube 06—Pre-MSMP Speed Data (Eastbound Only) for One-Week
Period from 8/11/05 to 8/17/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
68.18467
5.640114
68.61222
62.20573
73.74139
74.47931
76.27703
62.7645
0.751147
0.403512
0.064719
0.00709
0.003202
62,764
Table 4.34: Tube 07—Pre-MSMP Speed Data (All Lanes) for One-Week Period
from 8/19/05 to 8/26/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
72.2806461
5.50184194
72.4209476
66.6242513
77.8410966
78.902847
79.9645973
64.501474
0.92075223
0.70295271
0.28379307
0.04833281
0.0108185
144,105
A1-81
4.3. Historical Speed Data from ATR Located Outside the Enhanced Enforcement Zones
There was one ATR located on a Rural Freeway Outside the Enhanced Enforcement
Zones. It was ATR-200, on I-94, near Hasty, in Wright County. Unfortunately, only
limited historical data were available for this ATR—these data were from the last three
time periods in 2005. [In 2002-2003, there were no available data for five time periods
and the data from the remaining three time periods were unreliable; in 2003-2004, the
data from all eight time periods were unreliable; and in 2004-2005, there were no
available data for one time period and the data from the four others were unreliable]
The speed data from the last three time periods in 2005 are presented in Tables 4.35
through 4.37.
Table 4.35: ATR-200—One Year of Historical Speed Data for Four-Week Period
from 24/4/05 to 5/21/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
73.3104
8.638339
73.46584
65.93416
80.04184
82.54562
90.09961
52.6945
0.883362
0.704796
0.409347
0.150836
0.050987
1,206,904
A1-82
Table 4.36: ATR-200—One Year of Historical Speed Data for Eight-Week Period
from 5/22/05 to 7/16/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
73.48489
8.050421
73.44316
66.42025
79.90216
82.30838
84.87587
54.8998
0.903593
0.71492
0.402823
0.144954
0.047583
2,646,530
Table 4.37: ATR-200—One Year of Historical Speed Data for Four-Week Period
from 7/16/05 to 8/13/05
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2004-2005
72.96212
7.520329
73.57437
66.36785
79.14676
79.95082
83.16228
57.4103
0.894813
0.731006
0.407864
0.096942
0.02272
1,297,731
A1-83
Section 5: Urban Freeway Speed Data
The historical speed data obtained from the four ATRs located on Urban Freeways are
presented in this section of the report. There were no Tubes located on Urban Freeways.
Three of the four ATRs were located Within Enhanced Enforcement Zones—during the
MSMP, the speed limit increased from 55 mph to 60 mph at these three ATR locations.
The remaining ATR was located Outside the Enhanced Enforcement Zones—the speed
limit remained unchanged at 55 mph at the location of this ATR during the MSMP.
5.1. Historical Speed Data from ATRs Located Within Enhanced Enforcement Zones
Three of the four ATRs located on Urban Freeways were located Within Enhanced
Enforcement Zones. They were: (1) ATR 100, on Highway 100 near Brooklyn Center in
Hennepin County, (2) ATR I94, on I-94 South of the 57th Street Bridge in Hennepin
County, and (3) ATR-35WCD, on I-35W, near Roseville in Ramsey County.
The historical speed data for these three ATRs were limited. All three ATRs were
installed in the summer of 2005. For ATR-100, two weeks of speed data were collected
in September 2005, immediately before the beginning of the MSMP. For ATR-I94 and
ATR-35WCD, four weeks of data were collected in August and September 2005, also
immediately before the beginning of the MSMP. The speed data for these three ATRs
are presented in Tables 5.1, 5.2, and 5.3.
Table 5.1: ATR-100—Pre-MSP Historical Speed Data: Two Weeks from
September 12 to 25
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 (mph) pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
Pre-Test Period
60.5705781
10.27909416
61.79236416
55.29713709
68.48691619
69.7953862
73.14991021
57.5251283
0.283244024
0.092181181
0.025225017
0.006480191
0.001751304
1,089,474
A1-84
Table 5.2: ATR-I94—Pre-MSP Historical Speed Data: Four Weeks from August 29
to September 25
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 (mph) pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
Pre-Test Period
63.54484784
8.793828179
63.63568058
56.92105641
70.35334784
72.90581413
76.15878048
55.6580246
0.412797053
0.156921694
0.058977208
0.020241622
0.008568478
3,409,707
Table 5.3: ATR-35WCD—Pre-MSP Historical Speed Data: Four Weeks from
August 29 to September 25
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 (mph) pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
Pre-Test Period
60.00777635
12.65931618
62.55400024
53.76069938
69.30574595
70.9577538
73.70137875
48.2874093
0.351848424
0.117454168
0.026333842
0.005193913
0.001188849
3,030,663
A1-85
5.2. Historical Speed Data from ATR Located Outside the Enhanced Enforcement Zones
There was a single ATR located on an Urban Freeways Outside the Enhanced
Enforcement Zones. It was ATR 335, on I-35W at County Road 53 in Anoka. For this
ATR, there were historical data from the same time periods that were used in the MSMP.
In some cases, three years of historical speed data were available; in others, one or two
years of historical data were available. The historical speed data for ATR-335 are
presented in Tables 5.4 through 5.11.
Table 5.4: ATR-335—Three Prior Years of Historical Speed Data for Six-Week
Period from 9/26 to 11/6
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
73.87656
6.880343
73.93007
67.45805
79.81834
81.71504
83.88752
59.5129
0.937144
0.759882
0.429249
0.139472
0.024396
1,582,511
2003-2004
69.81129
7.318132
70.09963
62.98241
76.73458
78.30872
79.88287
57.749
0.788158
0.505996
0.205096
0.04628
0.010089
1,925,901
2004-2005
70.64652
8.154031
71.17619
64.23983
77.66896
79.19338
82.04418
58.3516
0.832392
0.580732
0.23754
0.073544
0.015957
1,940,361
Table 5.5: ATR-335—Three Prior Years of Historical Speed Data for Four-Week
Period from 11/7 to 12/4
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
74.13842
6.490825
74.13723
68.0747
79.75187
81.54689
83.76643
62.7613
0.950947
0.78679
0.440193
0.134847
0.022211
999,999
A1-86
2003-2004
69.45118
8.037613
69.98128
62.43936
76.77974
78.441
80.35199
56.0891
0.782387
0.498939
0.203566
0.053078
0.009356
1,143,282
2004-2005
70.67486
7.73537
71.07201
63.77391
77.76509
79.25671
82.14168
56.5569
0.819246
0.570224
0.242688
0.075084
0.016522
1,175,639
Table 5.6: ATR-335—Three Prior Years of Historical Speed Data for Eight-Week
Period from 12/5 to 1/29
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
73.57165
6.665367
73.66256
67.36859
79.44065
80.90804
83.4655
60.7561
0.933359
0.757391
0.40601
0.117753
0.020000
2,089,039
2003-2004
68.93586
9.266489
69.89191
61.31296
77.1273
78.70838
80.93603
50.2002
0.749178
0.494494
0.217274
0.059154
0.010257
2,161,836
2004-2005
69.70895
8.859521
70.50998
62.227
77.52456
79.09448
81.90345
53.4088
0.77399
0.530621
0.230404
0.07116
0.015576
2,179,324
Table 5.7: ATR-335—Three Prior Years of Historical Speed Data for Four-Week
Period from 1/30 to 2/26
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
72.77792
8.274691
73.40447
66.58345
79.32067
80.64951
83.37069
57.1677
0.905513
0.730222
0.392105
0.111934
0.020062
1,036,473
A1-87
2003-2004
68.02224
9.565674
69.23108
59.77593
76.68801
78.33515
79.98228
44.961
0.695203
0.464525
0.201241
0.049462
0.009223
1,081,635
2004-2005
71.05396
7.945000
71.48346
63.9078
78.33647
79.73863
82.88503
54.5458
0.824764
0.597458
0.268976
0.09068
0.020178
1,133,251
Table 5.8: ATR-335—Three Prior Years of Historical Speed Data for Eight-Week
Period from 2/27 to 4/23
2002-2003
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
(All Eight Weeks)
74.20185
7.061336
74.34384
67.79224
79.98286
82.05975
84.16402
60.8184
0.936417
0.781672
0.457452
0.148942
0.030136
2,135,087
2003-2004
(Two Weeks Only
2/27/04 to???)
69.51292795
8.336244446
70.56082393
62.10735805
77.04899934
78.41809206
79.78718479
52.1413914
0.761541491
0.53476357
0.224830554
0.042227874
0.009348445
553,568
2004-2005
(All Eight Weeks)
71.3637
7.49006
71.64489
64.96469
78.23534
79.60637
82.67246
56.6753
0.849237
0.613747
0.267989
0.085645
0.018956
2,384,645
Table 5.9: ATR-335—Two Prior Years of Historical Speed Data for Four-Week
Period from 4/24 to 5/21 [Speed Data Unavailable for 2003-2004]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
74.48518
7.225434
74.50987
67.68538
80.74401
82.67967
84.61533
59.0845
0.93795
0.774193
0.470201
0.169219
0.040064
1,216,267
A1-88
2004-2005
71.24093
7.564555
71.53518
64.77101
78.15533
79.54703
82.58977
56.6534
0.844887
0.604849
0.263363
0.083726
0.018612
1,262,150
Table 5.10: ATR-335—Two Prior Years of Historical Speed Data for Eight-Week
Period from 5/22 to 7/16 [Speed Data Unreliable for 2004-2005]
2002-2003
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
(All Eight Weeks)
71.86285
7.869484
71.87548
64.46737
78.97982
80.96459
84.15356
53.7819
0.838437
0.628419
0.286055
0.115124
0.036729
2,571,918
2003-2004
(Four Weeks Only
6/18/04 to 7/15/04)
70.74779
7.972139
71.26448
65.00586
77.33915
79.04475
81.9518
61.5505
0.850299
0.595263
0.218573
0.071997
0.015647
1,515,990
Table 5.11: ATR-335—Two Prior Years of Historical Speed Data for Four-Week
Period from 7/17 to 8/13 [Speed Data Unreliable for 2004-2005]
Measure
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Percent in 10 mph pace
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
Vehicle Total
2002-2003
71.208
7.516993
71.32988
64.38727
77.89204
79.38801
82.82779
56.9973
0.835021
0.591799
0.246661
0.079545
0.027304
1,335,728
A1-89
2003-2004
71.40808
7.693574
71.73898
65.43436
78.08574
79.51266
82.49922
59.4077
0.871027
0.628983
0.258126
0.082923
0.017056
1,470,983
6. Historical Crash Data
Historical crash data were available for all Minnesota trunk highways—including 2Lane/2-Way Highways, 4-Lane Highways, Rural Freeways, and Urban Highways. Some
of these highways had changes in speed limits during the MSMP, some had enhanced
enforcement during the MSMP, and speed data were available from some of them. In all,
there were twelve combinations of Road Type, Speed Limits, and Enforcement Status.
Table 6.1 lists the twelve combinations—along with the availability of speed data and the
total length of roadway for each combination.
Table 6.1: Combinations of Trunk Highway Type, Speed Limits During the MSMP,
and Enforcement Status (with Availability of Speed Data and Total Length of
Roadway)
Type of
Roadway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
Speed Limits
Increased—from 55
mph to 60 mph
Unchanged at 55
mph
Increased—from 55
mph to 60 mph
4-Lane Divided
Highway
4-Lane Divided
Highway
Unchanged at 65
mph
Unchanged at 65
mph
Rural Freeway
Unchanged at 70
mph
Unchanged at 70
mph
Rural Freeway
Urban Freeway
Urban Freeway
Urban Freeway
Urban Freeway
Urban Freeway
Increased—from 55
mph to 60 mph
Unchanged at 55
mph
Unchanged at 60
mph
Unchanged at 60
mph
Unchanged at 55
mph
Enforcement
Status
(Within/Outside
Enhanced
Enforcement
Zone)
Within
Outside
Outside
Within
Outside
Availability of
Speed Data
Available/
Unavailable
Available
(ATR)
Available
(ATR & Tube)
Available
(Tube)
Available
(ATR & Tube)
Available
(ATR)
Total Length of
Roadways
(in Miles)
316.790
7,593.783
474.511
52.219
550.525
Available
(ATR & Tube)
Available
(ATR)
265.246
27.337
89.397
Within
Available
(ATR)
Available
(ATR)
Unavailable
Outside
Unavailable
73.377
Within
Unavailable
11.234
Within
Outside
Within
Outside
A1-90
459.835
4.052
Table 6.1 shows that crash data were available from all the combinations for which speed
data were available, as well as from three combinations for which we did not have speed
data. The table also shows that there were great differences in the total length of roadway
for each combination—the range was from 7,593 miles (of 2-Lane/2-Way Highway, with
unchanged speed limits, that were outside the enhanced enforcement zones) to 4 miles (of
Urban Freeway, with unchanged speed limits, that were within the enhanced enforcement
zones).
While an enormous amount of speed data was available for analysis purposes, in contrast
there were orders of magnitude less crash data. Since crash data becomes more stable as
the sample size increases, we combined the crash data in several ways. First, instead of
examining the crash data obtained in any individual road segment, we combined the data
for each of the twelve combinations listed in Table 6.1. Second, we combined the crash
data for the five years prior to the MSMP.
The historical crash data are presented below in Tables 6.2 through 6.13. Each table has
three columns. In, the first column we present the crash data obtained in the five years
prior to the MSMP during the First MSMP Test Period—i.e., in the ten weeks between
9/26 and 12/4. In the second column, we present the crash data obtained in the five years
prior to the MSMP during the First and Second MSMP Test Periods—i.e., in the 22
weeks between 9/26 and 2/26. Then, in the third column, we present the crash data
obtained throughout the five years prior to the MSMP.
Please note that in the tables, the Crash Rate, the Severity Rate and the Fatal Crash Rate
are defined as follows.
• Crash Rate is the number of crashes per million vehicle miles traveled—i.e., (the
total number of crashes multiplied by 1,000,000) divided by (the average daily
traffic multiplied by the number of days in the time period multiplied by the
length of roadway).
• Severity Rate is [(the number of fatal crashes multiplied by 5) plus (the number
of A injury crashes multiplied by 4) plus (the number of B injury crashes
multiplied by 3) plus ( the number of C injury crashes multiplied by 2) plus (the
number of property damage crashes multiplied by 1)] divided by (the average
daily traffic multiplied by the number of days in the time period multiplied by the
length of roadway).
• Fatal Crash Rate is the number of fatal crashes per 100,000,000 vehicle miles
traveled—i.e., (the number of fatal crashes multiplied by 1,000,000,000) divided
by (the average daily traffic multiplied by the number of days in the time period
multiplied by the length of roadway).
A1-91
Table 6.2: Five-Year Historical Crash Data for 2-Lane/2-Way Highways for which
the Speed Limit Was Increased, from 55 mph to 60 mph, and that Were Within the
Enhanced Enforcement Zones during the MSMP
Period #1
Periods #1 & 2 Complete Year
Length of Roadway (miles)
316.790
316.790
316.790
Average Daily Traffic
3,861.809
3,876.057
3,890.059
Number of Fatal Crashes
7
15
33
Number of A Injury Crashes
10
30
59
Number of B Injury Crashes
34
79
170
Number of C Injury Crashes
and Unknowns
40
97
224
Number of Property Damage
Crashes
279
545
937
Total Crashes
370
766
1,423
Crash Rate
0.8641
0.8102
0.6320
Severity Rate
1.2518
1.2385
1.01978
Fatal Crash Rate
1.6348
1.5865
1.4657
Table 6.3: Five-Year Historical Crash Data for 2-Lane/2-Way Highways for which
the Speed Limit Was Unchanged, at 55 mph, and that Were Outside the Enhanced
Enforcement Zones during the MSMP
Period #1
Periods #1 & 2 Complete Year
Length (miles)
7,593.783
7,593.783
7,593.783
Average Daily Traffic
2,454.703
2,468.993
2,483.091
Number of Fatal Crashes
117
257
537
Number of A Injury Crashes
172
370
887
Number of B Injury Crashes
871
1801
4,124
Number of C Injury Crashes
and Unknowns
1,161
2,532
5,418
Number of Property Damage
Crashes
5,025
10,548
19,564
Total Number of Crashes
7,346
15,508
30,530
Crash Rate
1.1260
1.0742
0.8862
Severity Rate
1.7218
1.6472
1.4225
Fatal Crash Rate
1.7933
1.7802
1.5588
A1-92
Table 6.4: Five-Year Historical Crash Data for 2-Lane/2-Way Highways for which
the Speed Limit Was Increased, from 55 mph to 60 mph, and that Were Outside the
Enhanced Enforcement Zones during the MSMP
Period #1
Periods #1 & 2 Complete Year
Length (miles)
474.511
474.511
474.511
Average Daily Traffic
2,700.2422
2,709.713
2,719.078
Number of Fatal Crashes
7
11
29
Number of A Injury Crashes
7
21
46
Number of B Injury Crashes
27
78
186
Number of C Injury Crashes
and Unknowns
45
109
209
Number of Property Damage
Crashes
201
401
441
Total Crashes
287
620
1,200
Crash Rate
0.6400
0.6262
0.5090
Severity Rate
0.9700
1.0020
0.8632
Fatal Crash Rate
1.5096
1.1110
1.2301
Table 6.5: Five-Year Historical Crash Data for 4-Lane Divided Highways for which
the Speed Limit Was Unchanged, at 65 mph, and that Were Within the Enhanced
Enforcement Zones during the MSMP
Period #1
Periods #1 & 2 Complete Year
Length (miles)
52.219
52.219
52.219
Average Daily Traffic
15,802.3379
15,951.606
16,098.850
Number of Fatal Crashes
3
4
18
Number of A Injury Crashes
3
12
27
Number of B Injury Crashes
25
51
108
Number of C Injury Crashes
and Unknowns
53
130
239
Number of Property Damage
Crashes
193
421
710
Total Crashes
277
618
1,102
Crash Rate
0.9591
0.9635
0.7175
Severity Rate
1.3884
1.4063
1.1134
Fatal Crash Rate
1.0387
0.6236
1.1720
A1-93
Table 6.6: Five-Year Historical Crash Data for 4-Lane Divided Highways for which
the Speed Limit Was Unchanged, at 65 mph, and that Were Outside the Enhanced
Enforcement Zones during the MSMP
Period #1
Periods #1 & 2 Complete Year
550.525
550.525
Length (miles)
550.525
Average Daily Traffic
11,655.9877
11,745.3069
11,823.397
Number of Fatal Crashes
14
38
102
Number of A Injury Crashes
42
86
179
Number of B Injury Crashes
205
512
1,051
Number of C Injury Crashes
and Unknowns
327
822
1,601
Number of Property Damage
Crashes
1,456
3,326
5,748
Total Crashes
2,044
4,694
8,681
Crash Rate
0.9093
0.9428
0.7300
Severity Rate
1.3182
1.3959
1.1208
Fatal Crash Rate
0.6228
0.7632
0.8577
Table 6.7: Five-Year Historical Crash Data for Rural Freeways for which the Speed
Limit Was Unchanged, at 70 mph, and that Were Within the Enhanced
Enforcement Zones during the MSMP
Period #1
Periods #1 & 2 Complete Year
265.246
265.246
Length (miles)
265.246
Average Daily Traffic
19,867.3712
20,068.640
20,267.145
Number of Fatal Crashes
14
37
66
Number of A Injury Crashes
23
60
102
Number of B Injury Crashes
85
287
561
Number of C Injury Crashes
and Unknowns
179
522
906
Number of Property Damage
Crashes
929
2,553
4,436
Total Crashes
1,230
3,459
6,071
Crash Rate
0.6669
0.8439
0.6181
Severity Rate
0.9239
1.1913
0.8827
Fatal Crash Rate
0.7591
0.9027
0.6720
A1-94
Table 6.8: Five-Year Historical Crash Data for Rural Freeways for which the Speed
Limit Was Unchanged, at 70 mph, and that Were Outside the Enhanced
Enforcement Zones during the MSMP
Period #1
Periods #1 & 2 Complete Year
459.835
459.835
Length (miles)
459.835
Average Daily Traffic
21,511.1002
21,699.037
21,824.690
Number of Fatal Crashes
18
45
93
Number of A Injury Crashes
25
48
113
Number of B Injury Crashes
183
513
1,015
Number of C Injury Crashes
and Unknowns
329
895
1,743
Number of Property Damage
Crashes
1,667
4,200
7,682
Total Crashes
2,222
5,701
10,646
Crash Rate
0.6418
0.7431
0.5806
Severity Rate
0.8850
1.0357
0.8252
Fatal Crash Rate
0.5199
0.5865
0.5072
Table 6.9: Five-Year Historical Crash Data for Urban Freeways for which the
Speed Limit Was Increased, from 55 mph to 60 mph, and that Were Within the
Enhanced Enforcement Zones during the MSMP
Period #1
Periods #1 & 2 Complete Year
27.337
27.337
Length (miles)
27.337
Average Daily Traffic
100,670.8394
100,988.341
101,300.921
Number of Fatal Crashes
4
6
22
Number of A Injury Crashes
12
28
50
Number of B Injury Crashes
71
151
332
Number of C Injury Crashes
and Unknowns
180
435
938
Number of Property Damage
Crashes
771
1,883
3,698
Total Crashes
1,038
2,503
5,040
Crash Rate
1.0776
1.1775
0.9962
Severity Rate
1.4659
1.5750
1.3598
Fatal Crash Rate
0.4153
0.2823
0.4348
A1-95
Table 6.10: Five-Year Historical Crash Data for Urban freeways for which the
Speed Limit Was Unchanged, at 55 mph, and that Were Outside the Enhanced
Enforcement Zones during the MSMP
Period #1
Periods #1 & 2 Complete Year
89.397
89.397
Length (miles)
89.397
Average Daily Traffic
89,555.6964
89,755.688
89,952.253
Number of Fatal Crashes
10
15
50
Number of A Injury Crashes
23
47
107
Number of B Injury Crashes
230
492
1,070
Number of C Injury Crashes
and Unknowns
749
1,803
3,995
Number of Property Damage
Crashes
3,690
8,844
17,745
Total Crashes
4,702
11,201
22,967
Crash Rate
1.6780
1.18129
1.5632
Severity Rate
2.1484
2.2966
2.0163
Fatal Crash Rate
0.3569
0.2428
0.3403
Table 6.11: Five-Year Historical Crash Data for Urban Freeways for which the
Speed Limit Was Unchanged, at 60 mph, and that Were Within the Enhanced
Enforcement Zones during the MSMP
Period #1
Periods #1 & 2 Complete Year
Length (miles)
4.052
4.052
4.052
Average Daily Traffic
96,190.5994
96,395.489
96,597.226
Number of Fatal Crashes
1
4
4
Number of A Injury Crashes
3
3
4
Number of B Injury Crashes
8
18
56
Number of C Injury Crashes
and Unknowns
17
46
129
Number of Property Damage
Crashes
109
262
588
Total Crashes
138
333
781
Crash Rate
1.0116
1.1072
1.0921
Severity Rate
1.3488
1.4630
1.4683
Fatal Crash Rate
0.7330
1.3300
0.5594
A1-96
Table 6.12: Five-Year Historical Crash Data for Urban Freeways for which the
Speed Limit Was Unchanged, at 60 mph, and that Were Outside the Enhanced
Enforcement Zones during the MSMP
Period #1
Periods #1 & 2 Complete Year
Length (miles)
73.377
73.377
73.377
Average Daily Traffic
93,679.0849
93,431.901
93,187.430
Number of Fatal Crashes
7
12
30
Number of A Injury Crashes
8
22
56
Number of B Injury Crashes
140
299
720
Number of C Injury Crashes
and Unknowns
390
961
2,169
Number of Property Damage
Crashes
1,845
4,515
9,413
Total Crashes
2,390
5,809
12,388
Crash Rate
0.9934
1.1004
0.9916
Severity Rate
1.2935
1.4173
1.3036
Fatal Crash Rate
0.2910
0.2273
0.2401
Table 6.13: Five-Year Historical Crash Data for Urban Freeways for which the
Speed Limit Was Unchanged, at 55 mph, and that Were Within the Enhanced
Enforcement Zones during the MSMP
Period #1
Periods #1 & 2 Complete Year
Length (miles)
11.234
11.234
11.234
Average Daily Traffic
125,574.6946
126,003.032
126,424.976
Number of Fatal Crashes
3
5
14
Number of A Injury Crashes
0
3
16
Number of B Injury Crashes
28
83
205
Number of C Injury Crashes
and Unknowns
152
382
828
Number of Property Damage
Crashes
618
1,530
3,022
Total Crashes
801
2,003
4,085
Crash Rate
1.6223
1.8377
1.5743
Severity Rate
2.0679
2.3671
2.0915
Fatal Crash Rate
0.6076
0.4587
0.5395
A1-97
Appendix 2
Minnesota Speed Management Project: Deliverable #4—
Data Analysis for the First Test Period
Kathleen A. Harder, Ph.D. and John R. Bloomfield, Ph.D.
Center for Human Factors Systems Research and Design,
University of Minnesota, Suite 225
1425 University Ave. S.E.
Minneapolis, MN 55414
Contents
Page
Section 1. Introduction …………………………………………………………………..3
1.1 Background ……………………………………………………………….3
1.2 Organization of This Report ……………………………………………..6
Section 2. Summary of Findings during the First MSMP Test Period ………..……….7
2.1 Overall Effect of the MSMP during the First Enhanced
Enforcement and First Regular Enforcement Period …………………….7
2.2 Effect of the MSMP on 2-Lane/2-Way Highways ………………………8
2.3 Effect of the MSMP on 4-Lane Divided Highways ………………………11
2.4 Effect of the MSMP on Rural Freeways …………………………………14
2.5 Effect of the MSMP on Urban Freeways ………………………………...16
2.6 Crash Rates During the First MSMP Period ……………………………19
2.7 Citation Data During the First MSMP Period ………………………….20
Section 3. Speed Data Obtained on 2-Lane/2-Way Highways …..……………………21
3.1 Speed Data from ATRs Located Within Enhanced
Enforcement Zones ………………………………………………………21
3.2 Speed Data from ATRs Located Outside Enhanced
Enforcement Zones ………………………………………………………32
3.3 Overall Effect of the MSMP on 2-Lane/2-Way Highways ………………49
Section 4. Speed Data Obtained on 4-Lane Divided Highways ….…………………..53
4.1 Speed Data from ATRs Located Within Enhanced
Enforcement Zones ………………………………………………………53
4.2 Speed Data from One ATR Located Outside Enhanced
Enforcement Zones ………………………………………………………70
4.3 Overall Effect of the MSMP on 4-Lane Divided Highways ……………74
Section 5. Speed Data Obtained on Rural Freeways …………………………………77
5.1 Speed Data from ATRs Located Within Enhanced
Enforcement Zones ………………………………………………………77
5.2 Speed Data from One ATR Located Outside Enhanced
Enforcement Zones ………………………………………………………88
5.3 Overall Effect of the MSMP on Rural Freeways ………………………..92
Section 6. Speed Data Obtained on Urban Freeways ………………………………….96
6.1 Speed Data from ATRs Located Within Enhanced
Enforcement Zones ………………………………………………………97
6.2 Speed Data from One ATR Located Outside Enhanced
Enforcement Zones ……………………………………………………109
6.3 Overall Effect of the MSMP on Urban Freeways ………………………114
Section 7. Crash Data ………………………………………………………………...118
Section 8. Citation Data ………………………………………………………………126
A2-2
Section 1. Introduction
1.1 Background
This report contains the results of the analysis of data obtained during the first testing
period of the Minnesota Speed Management Program (MSMP). The Minnesota Speed
Management Program (MSMP) is a cooperative project between the Minnesota
Department of Transportation (Mn/DOT) and the Minnesota Department of Safety
(DPS). The program, which began on 9/26/05 and ends on 8/13/06, involves:
• Raising the speed limit on select roadways in Minnesota from 55 mph to 60 mph
in order to align the speed limit more closely with the design speed of the
roadways.
• Increasing the presence of enforcement officers along selected areas of these
roadways and other high-design roadways for selected periods of time.
The MSMP involves the following four types of roadway—(1) 2-Lane/2-Way Highways,
(2) 4-Lane Divided Highways, (3) Rural Freeways, and (4) Urban Freeways.
This report presents the University of Minnesota’s assessment of effectiveness of the
MSMP during its first test period, between 9/26/05 and 12/04/05. The test period had
two phases. In the first phase, lasting six weeks between 9/26/05 and 11/06/05, there was
Enhanced Enforcement on some roadways; while in the second phase, lasting four weeks
between 11/07/05 and 12/04/05 there was Regular Enforcement on those same roads.
Table 1.1 shows Enforcement status throughout the MSMP.
Table 1.1: Enforcement Status During the MSMP
Enforcement status
Enhanced Enforcement Period #1
Regular Enforcement Period #1
Enhanced Enforcement Period #2.
Regular Enforcement Period #2
Enhanced Enforcement Period #3.
Regular Enforcement Period #3
Enhanced Enforcement Period #4
Regular Enforcement Period #4
Time Period
9/26/05 to 11/6/05
11/7/05 to 12/4/05
12/5/05 to 1/29/06
1/30/06 to 2/26/06
2/27/06 to 4/23/06
4/24/06 to 5/21/06
5/22/06 to 7/16/06
7/17/06 to 8/13/06
In the two phases of the first test period, we analyzed speed data collected by Mn/DOT to
determine the effect of the MSMP on traffic speeds. The speed data provided by
Mn/DOT for the First Enhanced Enforcement Period and the First Regular Enforcement
Period were collected from a number of Automated Traffic Recorders (ATRs). Details of
the ATRs are given in Table 1.2.
A2-3
Table 1.2: ATRs Organized by Road Type
Type of
roadway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
ATR
210
219
220
179
198
199
222
4-Lane Divided
Highway
197
4-Lane Divided
Highway
4-Lane Divided
Highway
4-Lane Divided
Highway
4-Lane Divided
Highway
172
Rural freeway
175
Rural freeway
191
Rural freeway
208
Rural freeway
Rural freeway
227
200
Urban freeway
100
Urban freeway
I94
Urban freeway
35WC
D
335
Urban freeway
187
188
353
Location
US-71, 1 m. North of Blackduck,
Beltrami Co.
US-2, South East of Warba,
Itasca Co.
US-71, South of CR 89, Hubbard
Co.
USTH 59, South of Garvin, Lyon
Co.
USTH 212, East of TH 23,
Chippewa Co.
USTH 75, 0.55 m. N of Co Rd.
69, Pipestone Co.
MNTH 65, near Pliny, Aitkin Co.
Speed limit
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Unchanged at 55 mph
Within/
Outside
Enforcement
Zone
Within
Within
Within
Outside
Unchanged at 55 mph
Outside
Unchanged at 55 mph
Outside
Unchanged at 55 mph
Outside
Unchanged at 65 mph
Within
Unchanged at 65 mph
Within
Unchanged at 65 mph
Within
Unchanged at 65 mph
Within
Unchanged at 65 mph
Outside
I-94, 0.5 miles South East of
Saulk Centre, Stearns Co.
I-35, North of Wyoming, Chisago
Co.
I-35, North of Owatanna, Steele
Co.
I-90, East of Alden, Freeborn Co.
I-94, Hasty, Wright Co.
Unchanged at 70 mph
Within
Unchanged at 70 mph
Within
Unchanged at 70 mph
Within
Unchanged at 70 mph
Unchanged at 70 mph
Within
Outside
Highway 100, near Brooklyn
Center, Hennepin Co.
I-94, South of 57th Street Bridge,
Hennepin Co.
I-35W, near Roseville, Ramsey
Co.
I-35W at County Road 53, Anoka
Co.
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Unchanged at 55 mph
Within
SR-60, 0.7 miles West of junction
with SR-4, (St. James) Watonwan
Co.
US-10, West of Dilworth, Clay
Co.
US-10, 0.8 miles West of Rice,
Benton Co.
US-52, North of Rochester,
Olmstead Co.
TH 169, South of CR 59,North of
Jordan, Scott Co.
A2-4
Within
Within
Outside
In Table 1.2, the ATRs are organized in terms of the type of roadway on which they are
located—i.e., whether they are on 2-Lane/2-Way Highways, 4-Lane Divided Highways,
Rural Freeways, or Urban Freeways. The table lists their locations, the speed limit (and
whether or not it changed for the MSMP), and whether the ATRs were located Within or
Outside an Enhanced Enforcement Zone. [Note the ATR data will be augmented by tube
data in the fourth and final test period.]
From the speed data obtained with the ATRs, we derived several speed measures for the
First Enhanced Enforcement Period and the First Regular Enforcement Period. The same
measures were also derived from historical speed data that were obtained during the same
calendar time periods. Where possible, we used historical speed data from the three years
prior to the MSMP. In order to compare the MSMP speed data with the historical data,
we conducted a series of statistical tests in which the following measures were
compared—(1) the mean speed, (2) the percentage of vehicles in the 10 mph pace, (3) the
proportion of vehicles traveling at 65 mph or more, (4) the proportion of vehicles
traveling at 70 mph or more, (5) the proportion of vehicles traveling at 75 mph or more,
(6) the proportion of vehicles traveling at 80 mph or more, and (7) the proportion of
vehicles traveling at 85 mph or more. [Please note that in addition, we derived the
following measures—(8) median speed, (9) 15th percentile, (10) 85th percentile, (11) 90th
percentile (12) 95th percentile, and (13) the total number of vehicles—though we did not
conduct statistical comparisons for the median speed or the percentile measures. We did
not conduct statistical analyses for these measures because the comparisons are not valid.
The speed data from which they are derived are collected in one 40-mph bin (from 0.01
mph to 40.00 mph), nine 5-mph bins (40.01 mph to 45.00 mph, 45.01 mph to 50.00 mph;
50.01 mph to 55.00 mph; 55.01 mph to 60.00 mph; 60.01 mph to 65.00 mph; 65.01 mph
to 70.00 mph; 70.01 mph to 75.00 mph; 75.01 mph to 80.00 mph; and 80.01 mph to
85.00 mph), and one 15-mph bin (from 85.01 mph to 100.00 mph) and no differentiation
within the bins is possible, which makes a statistical analysis invalid.]
To test for differences in the mean speeds we used the procedure for comparing
population means outlined by Kitchens (1987, p 369-373). For the comparisons
involving the percentage of vehicles in the 10 mph pace and proportions of vehicle
traveling at various speeds, we treated each distribution of speeds as a Bernoulli
population—i.e., a population in which each element is one of two possibilities, in this
case, (1) in or out of the 10 mph pace, or (2) above or below a selected speed (e.g., 75
mph). We then used the procedure for comparing population proportions described by
Kitchens (1987, pages 400-404). The statistical tests were conducted in two ways. First,
we conducted the tests in the traditional way, using n-values that were equal to the
number of vehicles that traveled by each ATRs in the test periods under consideration. In
the second, we used an extremely conservative correction, with n-values that were equal
to the number of hours in each test period—because it is likely that, when traffic is
congested, individual vehicles may travel at speeds which are not independent of each
other.
In addition, we analyzed crash data to determine whether there were changes in crash
rates during the MSMP. For comparison purposes, we combined the crash data from the
A2-5
First Enhanced Enforcement Period and the First Regular Enforcement Period and
compared that combined data with crash data obtained in the same calendar time period
during the five years prior to the MSMP.
We also examined the citation data that were obtained during the First Enhanced
Enforcement Period—in this case however, there no historical citation data were
available for comparison purposes.
1.2. Organization of this Report
The next section of this report, Section 2, presents summary data. Then, detailed
analyses are presented in subsequent sections of the report. Sections 3 through 6 present
speed data comparisons for each of the four road types, with individual comparisons for
each of the ATRs listed in Table 1.2. Section 7 presents the crash data comparisons.
And Section 8 presents the citation data.
A2-6
Section 2: Summary of Findings during the First MSMP Test Period
In the MSMP, we obtained speed data from 21 ATRs located throughout Minnesota.
Fourteen of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining seven were located Outside Enhanced Enforcement Zones. Seven ATRs were
located on 2-Lane/2-Way Highways, five were located on 4-Lane Divided Highways,
five on Rural Freeways, and four on Urban Freeways. The effect of the MSMP on the
speed data obtained at these ATRs is summarized in this section of the report.
2.1. Overall Effect of the MSMP during the First Enhanced and First Regular
Enforcement Periods
To provide a brief overall summary of the initial effect of the MSMP on driving speeds,
we focused on vehicles traveling at least 10 mph above the speed limit at the locations of
the ATRs Within the Enhanced Enforcement Zones during the MSMP. [It should be
noted that, on the 2-Lane/2-Way Highways and the Urban Freeways, at the locations
Within the Enhanced Enforcement Zones the speed limits were increased from 55 mph to
60 mph, while at the locations Outside the Enhanced Enforcement Zones the speed limits
were unchanged at 55mph. Also, the speed limits remained unchanged at 65 mph on 4Lane Divided Highways and at 70 mph on Rural Freeways.]
Table 2.1 shows the decrease or increase in the percentage of the vehicles traveling at
least 10 mph above the speed limit during the MSMP as compared with the percentages
traveling at those speeds before the MSMP was implemented. This means that, for the
ATRs located on the 2-Lane/2-Way Highways and the Urban freeways, the percentages
shown are for vehicles traveling at 70 mph or more—10 mph above the new speed limit
and 15 mph above the pre-MSMP speed limit. [Also it should also be noted that in Table
2.1, the decrease or increase in percentages are relative to one year earlier, with the
exceptions noted in the table.]
A2-7
Table 2.1: Summary of the Effect of the MSMP on the Percentage of Vehicles
Traveling at Least 10 mph Above the Speed Limits during the MSMP
Within the Enhanced Enforcement
Zones
Increase/
Increase/
Decrease during Decrease during
First Regular
First Enhanced
Enforcement
Enforcement
Period
Period
Outside the Enhanced Enforcement
Zones
Increase/
Increase/
Decrease during Decrease during
First Regular
First Enhanced
Enforcement
Enforcement
Period
Period
Road type
2-Lane/2-Way
-39.35%
-41.08%
+19.17%
Highways
4-Lane Divided
-10.36%
-13.76%
-26.77%*
Highways
Rural
-13.08%
-38.99%
-71.42%*
Freeways
Urban
-9.00%**
-15.71%**
-6.34%*
Freeways
*Speed data from one ATR located close to Enhanced Enforcement Zones.
**Historical speed data obtained one month before the start of the MSMP.
+26.97%
-46.15%*
-68.97%*
-14.05%*
Table 2.1 shows that, for all four road types, Within the Enhanced Enforcement Zones
there were overall decreases in the percentage of vehicles traveling at least 10 mph above
the speed limits. The table also shows that, for the 2-Lane/2-Way Highways Outside the
Enhanced Enforcement Zones there were increases in the percentage of vehicles
traveling at least 10 mph above the speed limits Within the Enhanced Enforcement Zones.
In contrast, for the other three road types Outside the Enhanced Enforcement Zones, there
were decreases in the percentage of vehicles traveling at least 10 mph above the speed
limits Within the Enhanced Enforcement Zones. It is of note that for these three road
types, in each case there was a single ATR Outside the Enhanced Enforcement Zones that
was located relatively close to one or two Enhanced Enforcement Zones.
Table 2.1 also shows that, with one exception, Within the Enhanced Enforcement Zones
the decreases in the percentages were greater in the Regular Enforcement Period—
probably because the effect of the MSMP was increasing though the Enhanced
Enforcement Period. If this suggestion is correct there may be still greater decreases
when the data from the Second Test Period is examined.
The data from which Table 2.1 was derived for each of the four road types is presented in
more detail in the remainder of the section of the report.
2.2. Effect of the MSMP on 2-Lane/2-Way Highways
In the MSMP, we obtained speed data from seven ATRs located on 2-Lane/2-Way
Highways—three of these ATRs were located Within Enhanced Enforcement Zones,
while the remaining four were located Outside Enhanced Enforcement Zones. The speed
limit was increased from 55 mph to 60 mph at the locations of the three ATRs Within
A2-8
Enhanced Enforcement Zones, while the speed limit remained unchanged at 55 mph at
the locations of the four ATRs Outside Enhanced Enforcement Zones.
In order to provide a brief overall summary of the effect of the MSMP, speed data from
the three ATRs Within Enhanced Enforcement Zones were combined. For this summary,
we focused on drivers traveling at least 10 mph above the new speed limit. Then, we
compared speed data from the Test Year with data from the previous year, when the
speed limit at the locations of the three ATRs was still 55 mph. Table 2.2 shows the
results of this comparison for the First Enhanced Enforcement Period.
Table 2.2: Effect of MSMP on 2-Lane/2-Way Highways during the First Enhanced
Enforcement Period at Three ATRs Within Enhanced Enforcement Zones
Sample Total
288,067
Sample Total
275,520
One Year Before MSMP
# Over 70 mph
15,176
First Enhanced Enforcement Period
# Over 70 mph
8,787
% Over 70 mph
5.26
% Over 70 mph
3.19
Result: 39.35% Decrease in Drivers Traveling Over 70 mph
Table 2.2 indicates that, for the three ATRs Within Enhanced Enforcement Zones on 2Lane/2-Way Highways, during the First Enhanced Enforcement Period, there was a
39.35% decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the
new speed limit.
A similar comparison was conducted for the First Regular Enforcement Period.
However, in this case, we were only able to combine data from two of the ATRs—as no
speed data were available from ATR-210 for this time period. The results of this
comparison using speed data from ATR-219 and ATR-220 are shown in Table 2.3.
Table 2.3: Effect of MSMP on 2-Lane/2-Way Highways during the First Regular
Enforcement Period at Two ATRs (ATR-219 and ATR-220) Within Enhanced
Enforcement Zones
Sample Total
131,850
Sample Total
120,639
One Year Before MSMP
# Over 70 mph
5,619
First Regular Enforcement Period
# Over 70 mph
3,034
% Over 70 mph
4.26
% Over 70 mph
2.51
Result: 41.08% Decrease in Drivers Traveling Over 70 mph
A2-9
Table 2.3 shows that, for two ATRs Within Enhanced Enforcement Zones on 2-Lane/2Way Highways, during the First Regular Enforcement Period, there was a 41.08%
reduction in the number of drivers traveling over 70 mph—i.e., 10 mph over the speed
limit.
We also combined the speed data obtained during the Test Periods from the four ATRs
Outside Enhanced Enforcement Zones, where there was no change in the level of
enforcement during the MSMP and no change in the speed limit. Then, we compared the
speed data from the Test Periods with the speed data from the previous year. In the
comparison, we focused on drivers traveling at 70 mph or more—while this is 10 mph
above the new speed limit Within Enhanced Enforcement Zones, it is 15 mph above the
actual speed limit at the locations of the four ATRs Outside Enhanced Enforcement
Zones. The results of this comparison for speed data obtained during the First Enhanced
Enforcement Period are shown in Table 2.4.
Table 2.4: Effect of MSMP on 2-Lane/2-Way Highways during the First Enhanced
Enforcement Period at Four ATRs Outside Enhanced Enforcement Zones
Sample Total
338,722**
Sample Total
352,459*
One Year Before MSMP
# Over 70 mph
9,902**
First Enhanced Enforcement Period
# Over 70 mph
12,279*
% Over 70 mph
2.92**
% Over 70 mph
3.48*
Result: 19.17% Increase in Drivers Traveling Over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-198 and ATR-199 during the time
period
*Numbers adjusted to account for limited availability of data from ATR-199 during the time period
Table 2.4 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on 2-Lane/2-Way Highways, during the First Enhanced Enforcement Period, there was a
19.17% increase in the number of drivers traveling over 70 mph—i.e., 10 mph above the
new speed limit Within Enhanced Enforcement Zones (and 15 mph above the current
speed limit Outside the Enhanced Enforcement Zones).
A similar comparison was conducted for the first Regular Enforcement Period. The
results of this comparison using speed data from the four ATRs located Outside
Enhanced Enforcement Zones are shown in Table 2.5.
A2-10
Table 2.5: Effect of MSMP on 2-Lane/2-Way Highways during the First Regular
Enforcement Period at Four ATRs Outside Enhanced Enforcement Zones
Sample Total
208,703
Sample Total
296,578*
One Year Before MSMP
# Over 70 mph
6,346
First Regular Enforcement Period
# Over 70 mph
7,978*
% Over 70 mph
3.04
% Over 70 mph
3.86*
Result—26.97% Increase in Drivers over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-199 and ATR-222 during the time
period
Table 2.5 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on the 2-Lane/2-Way Highways, during the First Regular Enforcement Period there was
a 26.97% increase in the number of drivers traveling over 70 mph—i.e., at 10 mph over
the new speed limit Within Enhanced Enforcement Zones (and 15 mph above the current
speed limit Outside Enhanced Enforcement Zones).
Comparisons between speed data from the ATRs located Within Enhanced Enforcement
Zones and the ATRs located Outside Enhanced Enforcement Zones should be treated
with caution. For example, it should be noted that the three ATRs located Within
Enhanced Enforcement Zones are all in Northern Minnesota, and that the proportion of
vehicles traveling at 70 mph or more varies between 0.021 and 0.052 for these ATRs. In
contrast, the four ATRs located Outside Enhanced Enforcement Zones are more widely
spread, with three in South Western Minnesota and one in East Central Minnesota. For
these four ATRs, the there is a much greater range in the proportion of vehicles traveling
at 70 mph or more—the proportion varies between 0.003, for ATR-179—one of the three
ATRs in South Western Minnesota—and 0.110 for ATR-222—which is located in East
Central Minnesota.
2.3. Effect of the MSMP on 4-Lane Divided Highways
In the MSMP, we obtained speed data from five ATRs located on 4-Lane Divided
Highways. Four of these ATRs were located Within Enhanced Enforcement Zones, while
the remaining ATR was located Outside the Enhanced Enforcement Zones. At the
locations of the four ATRs Within the Enhanced Enforcement Zones and the ATRs
Outside the Enhanced Enforcement Zones, the speed limit was unchanged—at 65mph—
during the MSMP.
In order to provide a brief overall summary of the effect of the MSMP, speed data from
the four ATRs Within Enhanced Enforcement Zones were combined. Then, we
compared speed data from the Test Year with data from the previous year. In this
comparison, we focused on drivers traveling at least 10 mph above the speed limit—i.e.,
A2-11
on drivers traveling at 75 mph or more. . Table 2.6 shows the results of this comparison
for the First Enhanced Enforcement Period.
Table 2.6: Effect of MSMP on 4-Lane Divided Highways during the First Enhanced
Enforcement Period at Four ATRs Within Enhanced Enforcement Zones
Sample Total
3,001,105*
Sample Total
2,932,050
One Year Before MSMP
# Over 75 mph
194,025*
First Enhanced Enforcement Period
# Over 75 mph
170,020
% Over 75 mph
6.47*
% Over 75 mph
5.80
Result: 10.36% Decrease in Drivers Traveling Over 75 mph
*Numbers adjusted to account for limited availability of data from ATR-187
Table 2.6 indicates that, for the four ATRs located Within Enhanced Enforcement Zones
on 4-Way Divided Highways, during the First Enhanced Enforcement Period, there was a
10.36% decrease in the number of drivers traveling over 75 mph—i.e., 10 mph over the
speed limit.
A similar comparison was conducted for the First Regular Enforcement Period. The
results of this comparison are shown in Table 2.7.
Table 2.7: Effect of MSMP on 4-Lane Divided Highways during the First Regular
Enforcement Period at Four ATRs Within Enhanced Enforcement Zones
Sample Total
1,830,762*
Sample Total
1,763,196
One Year Before MSMP
# Over 75 mph
119,779*
First Regular Enforcement Period
# Over 75 mph
99,515
% Over 75 mph
6.54*
% Over 75 mph
5.64
Result—13.76% Decrease in Drivers Traveling Over 75 mph
*Numbers adjusted because, for ATR-197, comparison data were from a 6-week time period.
Table 2.7 shows that, for the ATRs Within Enhanced Enforcement Zones on 4-Way
Divided Highways, during the First Regular Enforcement Period there was a 13.76%
reduction in the number of drivers traveling over 75 mph—i.e., 10 mph or more above
the speed limit.
We also examined the speed data obtained during the Test Periods from the single ATR
Outside the Enhanced Enforcement Zones, and compared the speed data from the Test
Year with data from the previous year. In this comparison, we again focused on drivers
traveling at 75 mph or more—10 mph above the speed limit. The results of this
A2-12
comparison for speed data obtained during the First Enhanced Enforcement Period are
shown in Table 2.8.
Table 2.8: Effect of MSMP at one ATR Outside the Enhanced Enforcement Zones
on a 4-Way Divided Highway During the First Enhanced Enforcement Period
Sample Total
980,861
Sample Total
958,013
One Year Before MSMP
# Over 75 mph
46,929
First Enhanced Enforcement Period
# Over 75 mph
33,543
% Over 75 mph
4.78
% Over 75 mph
3.50
Result: 26.77% Decrease in Drivers Traveling Over 75 mph
Table 2.8 shows that, for the single ATR located Outside the Enhanced Enforcement
Zones on a 4-Way Divided Highway, during the First Enhanced Enforcement Period,
there was a 26.77% decrease in the number of drivers traveling over 75 mph—i.e., 10
mph or more above the speed limit.
A similar comparison was conducted for the First Regular Enforcement Period. The
results of this comparison are shown in Table 2.9
Table 2.9: Effect of MSMP at one ATR Outside the Enhanced Enforcement Zones
on a 4-Way Divided Highway During the First Regular Enforcement Period
Sample Total
619,067
Sample Total
589,028
One Year Before MSMP
# Over 75 mph
29,749
First Regular Enforcement Period
# Over 75 mph
15,247
% Over 75 mph
4.81
% Over 75 mph
2.59
Result—46.15% Decrease in Drivers over 75 mph
Table 2.9 shows that, for the ATR located Outside the Enhanced Enforcement Zones on a
4-Way Divided Highway, during the First Regular Enforcement Period there was a
46.15% decrease in the number of drivers traveling over 75 mph—i.e., at 10 mph over
the speed limit.
Comparisons between speed data from the ATRs located Within Enhanced Enforcement
Zones and the ATR located Outside the Enhanced Enforcement Zones should be treated
with caution. The four ATRs located Within Enhanced Enforcement Zones are scattered
throughout Minnesota; while the single ATR Outside the Enhanced Enforcement Zones
is located a few miles to the South-West of the Twin Cities—many of the drivers
A2-13
traveling past this ATR may have traveled through Enhanced Enforcement Zones in the
Cities.
2.4. Effect of the MSMP on Rural Freeways
In the MSMP, we obtained speed data from five ATRs located on Rural Freeways—four
of these ATRs were located Within Enhanced Enforcement Zones, while the remaining
ATR was located Outside the Enhanced Enforcement Zones. At the locations of all five
ATRs the speed limit remained unchanged at 70 mph.
In order to provide a brief overall summary of the effect of the MSMP, speed data from
the ATRs Within Enhanced Enforcement Zones were combined. We were able to
combine speed data from ATR-175, ATR-191, and ATR-227—speed data were not
available from ATR-208 for this period. The combined speed data from the Test Periods
were compared with similar data from the previous year. In the comparison, we focused
on drivers traveling at least 10 mph above the speed limit—i.e., those traveling at 80 mph
or more. Table 2.10 shows the results of this comparison for the First Enhanced
Enforcement Period.
Table 2.10: Effect of MSMP on Rural Freeways during the First Enhanced
Enforcement Period at Three ATRs (ATR-175, ATR-191, and ATR-227) Within
Enhanced Enforcement Zones
Sample Total
3,234,647
Sample Total
3,144,439*
One Year Before MSMP
# Over 80 mph
299,211
First Enhanced Enforcement Period
# Over 80 mph
252,726*
% Over 80 mph
9.25
% Over 80 mph
8.04*
Result: 13.08% Reduction in Drivers over 80 mph
*Numbers adjusted to account for limited availability of data from ATR-175 and ATR-227 during the time
period
Table 2.10 indicates that, for three of the four ATRs Within Enhanced Enforcement
Zones on Rural Freeways, during the First Enhanced Enforcement Period, there was a
13.08% decrease in the number of drivers traveling at over 80 mph—i.e., 10 mph over
the speed limit—as compared to the month before the MSMP was implemented.
A similar comparison was conducted for the First Regular Enforcement Period.
However, in this case we were only able to use speed data from two ATRs (ATR-175 and
ATR-227)—this speed data for ATR-191 and ATR-208 were not reliable for this time
period. The results of this comparison using speed data from the three ATRs are shown
in Table 2.11.
A2-14
Table 2.11: Effect of MSMP on Rural Freeways During the First Regular
Enforcement Period at Two ATRs (ATR-175 and ATR-227) Within Enhanced
Enforcement Zones
Sample Total
835,018
Sample Total
806,314*
One Year Before MSMP
# Over 80 mph
54,635
First Regular Enforcement Period
# Over 80 mph
20,562*
% Over 80 mph
6.54
% Over 80 mph
2.55*
Result: 38.99% Reduction in Drivers over 80 mph
*Numbers adjusted to account for limited availability of data from ATR-175, ATR-208, and ATR-227
during the time period
Table 2.11 indicates that, for three of the four ATRs located Within Enhanced
Enforcement Zones on Rural Freeways, during the First Regular Enforcement Period,
there was a 38.99% decrease in the number of drivers traveling over 80 mph—i.e., 10
mph over the speed limit.
We also examined the speed data obtained during the Test Periods from the ATR that
was located Outside the Enhanced Enforcement Zones, and compared it with similar data
from the previous year. We focused on drivers traveling at 80 mph or more—10 mph
above the speed limit. The results of this comparison for speed data obtained during the
First Enhanced Enforcement Period are shown in Table 2.12.
Table 2.12: Effect of the MSMP on One ATR Outside the Enhanced Enforcement
Zones on a Rural Freeway During the First Enhanced Enforcement Period
Pre-MSMP Speed Data from 4/24/05 to 5/21/05
Sample Total
# Over 80 mph
% Over 80 mph
1,206,904
182,044
15.08
First Enhanced Enforcement Period
Sample Total
# Over 80 mph
% Over 80 mph
1,714,696
73,819
4.31
Result: 71.42% Decrease in Drivers Traveling over 80 mph
Table 2.12 shows that, for the ATR located Outside Enhanced Enforcement Zones on a
Rural Freeway, during the First Enhanced Enforcement Period, there was a 71.42%
decrease in the number of drivers traveling over 80 mph.
A similar comparison was conducted for the First Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 2.13.
A2-15
Table 2.13: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on a Rural Freeway During the First Regular Enforcement Period
Pre-MSMP Speed Data from 4/24/05 to 5/21/05
# Over 80 mph
% Over 80 mph
182,044
15.08
First Regular Enforcement Period
Sample Total
# Over 80 mph
% Over 80 mph
1,050,413
49,128
4.68
Sample Total
1,206,904
Result: 68.97% Decrease in Drivers Traveling over 80 mph
Table 2.13 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
a Rural Freeway, during the First Regular Enforcement Period there was a 68.97%
decrease in the number of drivers traveling over 80 mph.
For Rural Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
Zones should be treated with caution. It should be noted that the location of ATR that
was located Outside the Enhanced Enforcement Zones is between Enhanced Enforcement
Zones to both the North-West and the South-East. It is likely that most drivers passing
this ATR will have traveled through one or other of the Enhanced Enforcement Zones. [It
should also be noted that there are no other ATRs Outside the Enhanced Enforcement
Zones on Rural Freeways that could have been considered for comparison purposes for
this study.]
2.5. Effect of MSMP on Urban Freeways
In the MSMP, we obtained speed data from four ATRs located on Urban Freeways—
three of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining ATR was located Outside the Enhanced Enforcement Zones. The speed limit
was increased from 55 mph to 60 mph at the locations of the three ATRs Within
Enhanced Enforcement Zones, while the speed limit remained unchanged at 55 mph at
location of the ATR Outside the Enhanced Enforcement Zones
In order to provide a brief overall summary of the effect of the MSMP, speed data from
the three ATRs Within Enhanced Enforcement Zones were combined. For this summary,
we focused on drivers traveling at least 10 mph above the new speed limit. Then, we
compared speed data collected during the Enhanced Enforcement Period with pre-MSMP
speed data that were collected just before the Enhanced Enforcement began—this data
was collected two weeks during September 2005 for ATR-100, and four weeks during
August and September 2005 for ATR-I94 and ATR-35WCD. When the pre-MSMP data
were collected the speed limit at the locations of the three ATRs was still 55 mph. Table
2.14 shows the results of this comparison for the First Enhanced Enforcement Period.
A2-16
Table 2.14: Effect of MSMP on Urban Freeways during the First Enhanced
Enforcement Period at Three ATRs Within Enhanced Enforcement Zones
Sample Total
8,619,318*
Sample Total
12,988,307
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879*
First Enhanced Enforcement Period
# Over 70 mph
1,497 191
% Over 70 mph
12.67*
% Over 70 mph
11.53
Result: 9.00% Reduction in Drivers over 70 mph
Table 2.14 indicates that, for the three ATRs Within Enhanced Enforcement Zones on
Urban Freeways, during the First Enhanced Enforcement Period, there was a 9.00%
decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the new
speed limit—as compared to the month before the MSMP was implemented.
A similar comparison was conducted for the First Regular Enforcement Period. The
results of this comparison using speed data from the three ATRs are shown in Table 2.15.
Table 2.15: Effect of MSMP on Urban Freeways during the First Regular
Enforcement Period at Three ATRs Within Enhanced Enforcement Zones
Sample Total
8,619,318*
Sample Total
8,239,216
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879*
First Regular Enforcement Period
# Over 70 mph
880,238
% Over 70 mph
12.67*
% Over 70 mph
10.68
Result: 15.71% Reduction in Drivers over 70 mph
Table 2.15 indicates that, for the three ATRs located Within Enhanced Enforcement
Zones on Urban Freeways, during the First Regular Enforcement Period, there was a
15.71% decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the
new speed limit—as compared to the month before the MSMP was implemented.
We also examined the speed data obtained during the Test Periods from the ATR that
was located Outside the Enhanced Enforcement Zones. For this ATR location there was
no change in the level of enforcement during the MSMP and no change in the speed
limit. We compared the speed data from the Test Period with speed data from the
previous year. Again, we focused on drivers traveling at 70 mph or more—while this is
10 mph above the new speed limit Within Enhanced Enforcement Zones, it is 15 mph
above the actual speed limit at the location of the ATR Outside Enhanced Enforcement
A2-17
Zones. The results of this comparison for speed data obtained during the First Enhanced
Enforcement Period are shown in Table 2.16.
Table 2.16: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on an Urban Freeway during the First Enhanced Enforcement Period
Sample Total
1,940,361
Sample Total
1,868,362
One Year Before MSMP
# Over 70 mph
1,126,829
First Enhanced Enforcement Period
# Over70 mph
1,016,165
% Over 70 mph
58.07
% Over 70 mph
54.39
Result: 6.34% Decrease in Drivers Traveling over 70 mph
Table 2.16 shows that, for the ATR located Outside Enhanced Enforcement Zones on an
Urban freeway, during the First Enhanced Enforcement Period, there was a 6.34%
decrease in the number of drivers traveling over 70 mph—i.e., 10 mph above the new
speed limit Within Enhanced Enforcement Zones (and 15 mph above the current speed
limit Outside the Enhanced Enforcement Zones).
A similar comparison was conducted for the First Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 2.17.
Table 2.17: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on an Urban Freeway during the First Regular Enforcement Period
Sample Total
1,175,639
Sample Total
1,115,042
One Year Before MSMP
# Over 70 mph
670,378
First Regular Enforcement Period
# Over 70 mph
546,428
% Over 70 mph
57.02
% Over 70 mph
49.01
Result: 14.05% Decrease in Drivers Traveling over 70 mph
Table 2.17 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
an Urban Freeway, during the First Regular Enforcement Period there was a 14.05%
decrease in the number of drivers traveling over 70 mph—i.e., at 10 mph or more above
the new speed limit Within Enhanced Enforcement Zones (and 15 mph or more above the
current speed limit Outside Enhanced Enforcement Zones).
For Urban Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
A2-18
Zones should be treated with caution. It should be noted that the location of ATR that
was located Outside the Enhanced Enforcement Zones is only a few miles to the North of
an Enforced Enforcement Zone. And, most of the drivers traveling North past this ATR
will have traveled through that Enhanced Enforcement Zone. [It should also be noted
that, the locations of all the other ATRs Outside the Enhanced Enforcement Zones on
Urban Freeways that might have been considered for comparison purposes for this study
are also very close to Enhanced Enforcement Zones.]
2.6. Crash Rates During the First MSMP Period
During the First MSMP Test Period, crash data were available for all Minnesota trunk
highways. These trunk highways included 2-Lane/2-Way Highways, 4-Lane Highways,
Rural Freeways, and Urban Highways. Some of these highways had changes in speed
limits during the MSMP, some had enhanced enforcement during the MSMP, and speed
data were available from some of them. In all, there were twelve combinations of Road
Type, Speed Limits, and Enforcement Status. Table 2.18 lists the Crash Rate, the
Severity Rate, and the Fatal Crash Rate for each of these combinations during the first ten
weeks of the MSMP.
Table 2.18: Crash Rate, Severity Rate, and Fatal Crash Rate for Each Combination
of Trunk Highway Type, Speed Limits During the MSMP, and Enforcement Zone
During the First Ten-Week MSMP Period
Within Enforcement Zone
Outside Enforcement Zone
Road Type
Crash Severity
Fatal
Crash Severity
Fatal
And
Rate
Rate
Crash
Rate
Rate
Crash
Speed Limit Condition
Rate
Rate
2 Lane/2-Way Highway
Increase—55 to 60 mph 0.9910
1.5947
2.2781
0.5703
0.8116
1.0967
2 Lane/2-Way Highway
No Change—55 mph
—
—
—
1.0503
1.5628
1.3332
4 Lane/Divided Highway
No Change—65 mph
0.5847
0.7996
1.6241
0.8094
1.1623
1.0566
Rural Freeway
Unchanged—70 mph
0.7418
1.0168
1.0093
0.6868
0.9513
0.4112
Urban Freeway
Increase—55 to 60 mph 0.9767
1.3276
1.0173
—
—
—
Urban Freeway
No Change—55 mph
1.4349
1.8505
0.0000
1.6390
2.0924
0.3528
Urban Freeway
No Change—60 mph
0.7922
1.1163
0.0000
1.0008
1.3195
0.2125
A2-19
2.7. Citation Data During the First Enhanced Enforcement Period
During the First MSMP Enhanced Enforcement Period citation data were collected for all
the highways on which there was Enhanced Enforcement. These data are summarized in
Table 2.19. The table presents, for each of the four highway types in the MSMP, the
Number of Speed Citations and the Number of Speed Warnings that were given during
the First Enhanced Enforcement Period, as well as the Number of Vehicles that were
Stopped and the Number of Hours of Enforcement.
Table 2.19: Citation Data for the Four Types of Highways on Which ATRs Were
Located
Type of
Highway
2-Lane/2-Way
Highway
4-Lane
Divided
Highway
Rural Freeway
Urban
Freeway
Number of
Speed Citations
Number of
Speed Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
677
2,416
3,330
1,312
893
997
1,225
1,101
2,248*
2,205
979
852*
1,388
923
2,671
918
4,742
10,454*
4,061*
Total
3,955
*Probably underestimates.
A2-20
Section 3. Speed Data Obtained on 2-Lane/2-Way Highways
We obtained speed data from seven ATRs that were located on 2-Lane/2-Way Highways.
Three of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining four were located Outside Enhanced Enforcement Zones. During the MSMP,
at the locations of the three ATRs Within the Enhanced Enforcement Zones, the speed
limit was increased from 55 mph to 60 mph and there was Enhanced Enforcement at
various times. In contrast, at the locations of the four ATRs Outside the Enhanced
Enforcement Zones, the speed limit remained unchanged at 55 mph and there was no
change in the enforcement level during the MSMP.
In this section of the report, for the ATRs located Within Enhanced Enforcement Zones
and the ATRs located Outside Enhanced Enforcement Zones, we present comparisons of
the speed data obtained during the Test Year with the speed data obtained at those same
ATRs in the three years prior to the MSMP. Comparisons using the speed data from the
ATRs located Within Enhanced Enforcement Zones are presented first. Then, we present
comparisons using the speed data from the ATRs located Outside Enhanced Enforcement
Zones.
In making the comparisons between the speed data obtained during the Test Year and the
speed data obtained prior to the MSMP, we used two statistical tests. The first test was
used to examine differences in the mean speeds—for this we used the procedure for
comparing population means outlined by Kitchens (1987, p 369-373). The second test
was used to explore differences in the percentage of vehicles in the 10 mph pace and in
the differences in the proportions of vehicle traveling at various speeds. For this test, we
treated the distribution of speeds as a Bernoulli population—i.e., a population in which
each element is one of two possibilities, in this case, (1) in or out of the 10 mph pace, or
(2) above or below a selected speed (e.g., 75 mph). We then used the procedure for
comparing population proportions described by Kitchens (1987, pages 400-404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
ATR in the time periods under consideration. Second, the tests were conducted using an
extremely conservative correction, with n-values equal to the number of hours in each
test period —the rationale for this was that it is possible, when traffic is congested, that
individual vehicles may travel at speeds which are not independent of each other.
3.1. Speed Data from ATRs located Within Enhanced Enforcement Zones
The three ATRs located Within Enhanced Enforcement Zones on 2-Lane/2-Way
Highways were as follows: (1) ATR-210, on US-71, near Blackduck in Beltrami County,
(2) ATR-219, on US-2, near Warba in Itasca County, and (3) ATR-220, on US-71, South
of CR 89 in Hubbard County. At the locations of all three of these ATRs, the speed limit
was increased from 55 mph to 60 mph during the MSMP. The effect of the MSMP on
A2-21
the speed data at each of these three ATRs is reported in this section. It is reported ATR
by ATR—with the effect of the MSMP in the First Enhanced Enforcement Period
followed by its effect in the First Regular Enhancement Period.
For each of the three ATRs Within Enhanced Enforcement Zones, two tables are
presented for each time period. In the first of these tables speed data from the Test Year
are compared with the available historical speed data. Where possible speed data from
the three years prior to the MSMP are included in this table—however, in some cases
data are only available from one or two of the prior years. Also in some cases, speed data
are not available from the whole of the First Enhanced Enforcement Period or the whole
of the First Regular Enhancement Period—in these cases the dates from which the data
are available are noted in the table. In the second of the two tables for each ATR, the
focus is on drivers traveling at least 5 mph and at least 10 mph above the new speed limit
adopted for the MSMP—i.e., on drivers traveling at 65 mph or more and at 70 mph or
more. In this second table, we present the number (and proportion) of vehicles traveling
above these speeds throughout the six-week Enhanced Enforcement Period or the fourweek Regular Enhancement Period. We also present the average number of vehicles
traveling above these speeds every day. Then, the table presents the decrease in the
number of vehicles relative to the number that were traveling at these speeds before the
MSMP. It should be noted that, in each of three years before the MSMP was adopted,
these speeds (of 65 mph or more and 70 mph or more) were 10 mph and 15 mph above
the pre-MSMP speed limit.
A2-22
ATR-210—Enhanced Enforcement Period #1
Table 3.1 (a): ATR-210—Speed Data from Enhanced Enforcement Period #1
Compared with Speed Data from Three Previous Years
Measure
Test Period
(9/26/05 to
11/6/05)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
60.30066
-1.10899**
-0.26483**
-0.60926**
Percent in 10
mph pace
67.8035
+8.0162**
+7.2113**
+8.3197**
0.182621
-0.07596**
-0.05159**
-0.0655**
0.051927
-0.03114**
-0.01963*
-0.02735**
0.014639
-0.01226*
-0.00795*
-0.0114*
0.003684
-0.0039*
-0.00209*
-0.00457*
0.001325
-0.00142*
-0.00086*
-0.00166*
51,303
54,726
52,282
48,578
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.1 (b): ATR-210—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard
deviation (mph)
Median (mph)
15th percentile
(mph)
85th percentile
(mph)
th
90 percentile
(mph)
95th percentile
(mph)
Test Period
(9/26/05 to
11/6/05)
7.52737*
60.85877
55.34646
66.24799
68.16085
70.25836
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-23
Table 3.2 (a): ATR-210—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #1 and During the Previous Three
Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
9,369
223
-93
-63
-80
2,664
63
-38
-24
-33
51,303
1,222
—
—
—
Table 3.2 (b): ATR-210—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #1 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.182621
0.182621
-0.0760
-0.0516
-0.0655
0.051927
0.051927
-0.0311
-0.0196
-0.0274
51,303
1,222
—
—
—
ATR-210—Regular Enforcement Period #1
Unfortunately, for ATR-210 during the first Regular Enforcement Period—i.e., between
11/07/05 and 12/05/05—speed data were only available for the first two days of the
period, and for part of the third day. This is insufficient data on which to base reliable
inferences. Therefore no data are reported for ATR-210 in this time period.
A2-24
ATR-219—Enhanced Enforcement Period #1
Table 3.3: ATR-219 (a)—Speed Data from Enhanced Enforcement Period #1
Compared with Speed Data from Three Previous Years
Measure
Test Period
(9/26/05 to
11/6/05)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
61.82446
-0.326354**
-0.42527**
+0.369921**
Percent in 10
mph pace
82.2806
+6.3549**
+8.3169**
+13.7561**
0.111612
-0.064133**
-0.086907**
-0.086123**
0.022052
-0.017367**
-0.024888**
-0.032072**
0.006554
+0.002969*
-0.005683*
-0.006944*
0.002563
ns
-0.000647*
-0.000376*
0.001335
+0.000679*
+0.000454*
ns
139,304
147,845
149,870
153,129
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.3: ATR-219 (b)—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard
deviation (mph)
Median (mph)
15th percentile
(mph)
85th percentile
(mph)
th
90 percentile
(mph)
95th percentile
(mph)
Test Period
(9/26/05 to
11/6/05)
4.62501*
62.08943
58.16104
64.71232
65.64828
68.43972
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-25
Table 3.4 (a): ATR-219—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #1 and During the Previous Three
Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
15,548
370
-212
-288
-286
3,072
73
-58
-83
-106
139,304
3,317
—
—
—
Table 3.4 (b): ATR-219—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #1 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.11161
0.11161
-0.06413
-0.086907
-0.086123
0.02205
0.02205
-0.01737
-0.024888
0.032072
139,304
3,317
—
—
—
A2-26
ATR-219—Regular Enforcement Period #1
Table 3.5 (a): ATR-219—Comparison of Speed Data from Regular Enforcement
Period #1 Compared with Speed Data from Three Previous Years
Measure
Test Period
(11/07/05 to
12/04/05)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
60.91249
-0.86799**
-0.53562**
-0.34023**
Percent in 10
mph pace
79.597
+3.6708**
+6.0751**
+12.4735**
0.100317
-0.0583**
-0.06974**
-0.10124**
0.020669
-0.01495*
-0.01759*
-0.03738**
0.006067
-0.00252*
-0.00358*
-0.00801*
0.002364
ns
ns
-0.00057*
0.001143
+0.000377*
ns
ns
76,976
84,817
85,924
90,066
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.5 (b): ATR-219—Additional Speed Data from Regular Enforcement
Period #1
Measure
Standard
deviation (mph)
Median (mph)
15th percentile
(mph)
85th percentile
(mph)
th
90 percentile
(mph)
95th percentile
(mph)
Test Period
(11/07/05 to
12/04/05)
5.67263*
61.66298
56.62335
64.58519
65.0199
68.1587
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-27
Table 3.6 (a): ATR-219—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #1 and During the Previous Three Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
7,722
278
-160
-192
-278
1,591
57
-41
-48
-103
76,976
2,749
—
—
—
Test
Period
(11/07/05
to
12/04/05)
Table 3.6 (b): ATR-219—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #1 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.100317
0.100317
-0.0583
-0.06974
-0.10124
0.020669
0.020669
-0.01495
-0.01759
-0.03738
76,976
2,749
—
—
—
A2-28
ATR-220—Enhanced Enforcement Period #1
Table 3.7 (a): ATR-220—Speed Data from Enhanced Enforcement Period #1
Compared with Speed Data from One Year Earlier
Measure
Test Period
(9/26/05 to 10/09/05)
Decrease/Increase as
Compared to One Year
Earlier
Mean (mph)
60.77744
-0.44071**
Percent in 10 mph pace
75.7831
+5.3968**
0.141875
-0.04803**
0.035931
-0.02024**
0.00782
-0.00513*
0.002402
-0.00156*
0.000707
-0.00058*
84,913
85,496
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.7 (b): ATR-220—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard
deviation (mph)
Median (mph)
15th percentile
(mph)
85th percentile
(mph)
th
90 percentile
(mph)
95th percentile
(mph)
Test Period
(9/26/05 to
11/6/05)
6.47458*
61.30253
56.3233
64.91611
66.97627
69.33601
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-29
Table 3.8 (a): ATR-220—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #1 and One Year Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(9/26/05 to
10/09/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
12,047
287
-97
3,051
73
-41
84,913
2,022
—
Table 3.8 (b): ATR-220—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #1 and One Year Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(9/26/05 to
10/09/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.141875
0.141875
-0.04803
0.035931
0.035931
-0.02024
84,913
2,022
—
A2-30
ATR-220—Regular Enforcement Period #1
Table 3.9 (a): ATR-220—Comparison of Speed Data from Regular Enforcement
Period #1 with Speed Data from One Year Earlier
Measure
Test Period
(11/07/05 to 12/04/05)
Decrease/Increase as
Compared to One Year
Earlier
Mean (mph)
58.25533
-2.97232**
Percent in 10 mph pace
56.2803
-0.13709**
0.128851
-0.06006**
0.033049
-0.02219**
0.0071
-0.00587*
0.00229
-0.00217*
0.00071
-0.00069*
43,663
47,033
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.9 (b): ATR-220—Additional Speed Data from Regular Enforcement
Period #1
Measure
Standard
deviation (mph)
Median (mph)
15th percentile
(mph)
85th percentile
(mph)
90th percentile
(mph)
th
95 percentile
(mph)
Test Period
(11/07/05 to
12/04/05)
9.76298*
60.351
52.20626
64.73508
66.50574
69.11529
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-31
Table 3.10 (a): ATR-220—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #1 and One Year Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
5,626
201
-97
1,443
52
-35
43,663
1,559
—
Table 3.10 (b): ATR-220—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #1 and One Year Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.128851
0.128851
-0.06006
0.033049
0.033049
-0.02219
43,663
1,559
—
3.2. Speed Data from ATRs located Outside Enhanced Enforcement Zones
There were four ATRs located Outside Enhanced Enforcement Zones on 2-Lane/2-Way
Highways. These ATRs were as follows—(1) ATR-179, on USTH 59, near Garvin, in
Lyon County, (2) ATR-198, on USTH 212, East of TH 23, in Chippewa County, (3)
ATR-199, on USTH 75, North of CR 69, in Pipestone County, and ATR-222, on MNTH
65, near Pliny, in Aitkin County. During the MSMP, at the locations of the ATRs located
Outside Enhanced Enforcement Zones, speed limits remained unchanged—at 55 mph—
and there were no changes in enforcement. For each of these ATRs, the speed data
obtained during 2005, when the MSMP occurred, was compared with the historical speed
data. These comparisons are reported site by site, first for the six-week time period
between 9/26 and 11/6, when the First Enhanced Enforcement Period occurred during the
MSMP, and then for the four-week time period between 11/7 and 12/4, when the First
Regular Enhancement Period occurred during the MSMP.
For each of the four ATRs located Outside Enhanced Enforcement Zones (as for the
ATRs located Within Enhanced Enforcement Zones), two tables are presented for each
time period. In the first table, speed data from the Test Year is compared with the
historical speed data. We include speed data from the three years prior to the MSMP in
the table, whenever possible—it should be noted that in some cases data are only
A2-32
available from one or two prior years. Also in some cases, speed data are not available
from the whole of the six-week Enhanced Enforcement Period or the four-week Regular
Enhancement Period—in these cases the dates from which the data are available are
noted in the table. In the second of the tables for each of the ATRs located Outside
Enhanced Enforcement Zones, the focus is on drivers traveling at least 5 mph and at least
10 mph above the new speed limit adopted for the MSMP—i.e., drivers traveling at least
65 mph and at least 70 mph). It should be noted that during the MSMP, as well as during
the three years before it was adopted, these speeds (of at least 65 mph and at least 70
mph) were 10 mph and 15 mph above the actual speed limit at the locations of the four
ATRs located Outside Enhanced Enforcement Zones. In this second table, we present the
number and proportion of vehicles traveling above these speeds throughout the First
Enhanced Enforcement Period or the First Regular Enhancement Period. We also
present the average number of vehicles traveling above these speeds every day. Then, the
table presents the decrease in the number of vehicles relative to the number that were
traveling at these speeds before the Test Year.
A2-33
ATR-179—Enhanced Enforcement Period #1
Table 3.11 (a): ATR-179—Comparison of Speed Data from Enhanced Enforcement
Period #1 with Speed Data from One Year Earlier
Measure
Test Period
(9/26/05 to 11/6/05)
Decrease/Increase as
Compared to One Year
Earlier
Mean (mph)
55.44772491
-0.29397**
Percent in 10 mph pace
68.9757435
+2.4862*
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
0.016226424
0.003392284
0.000949839
0.00047492
0.000180922
-0.0065975*
-0.0006781*
ns
+0.000222*
ns
Vehicle Total
88,436
86,970
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.11 (b): ATR-179—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard
deviation (mph)
Median (mph)
15th percentile
(mph)
85th percentile
(mph)
90th percentile
(mph)
95th percentile
(mph)
Test Period
(9/26/05 to
11/6/05)
6.71379*
56.21200011
50.67960067
61.13259235
62.57809742
64.02360248
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-34
Table 3.12 (a): ATR-179—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #1 and One Year Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(9/26/05 to
11/06/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
1,435
34
-14
300
7
-1
88,436
2,106
—
Table 3.12 (b): ATR-179—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #1 and One Year Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(9/26/05 to
11/06/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.016226
0.016226
-0.006598
0.003392
0.003392
-0.000678
88,436
2,106
—
A2-35
ATR-179—Regular Enforcement Period #1
Table 3.13 (a): ATR-179—Comparison of Speed Data from Regular Enforcement
Period #1 with Speed Data from One Year Earlier
Measure
Test Period
(11/07/05 to 12/04/05)
Decrease/Increase as
Compared to One Year
Earlier
Mean (mph)
53.339618
-1.35666434**
Percent in 10 mph pace
57.35894
-6.381603**
0.0127862
-0.00734536*
0.0028329
ns
0.00084220
ns
0.00047852
+0.000239738*
0.00026797
+0.000176132*
52,244
54,442
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.13 (b): ATR-179—Additional Speed Data from Regular Enforcement
Period #1
Measure
Standard
deviation (mph)
Median (mph)
15th percentile
(mph)
85th percentile
(mph)
th
90 percentile
(mph)
95th percentile
(mph)
Test Period
(11/07/05 to
12/04/05)
8.99339*
54.989826
47.754419
59.946185
61.73142
63.605308
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-36
Table 3.14 (a): ATR-179—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #1 and One Year Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
668
24
-14
148
5
-1
52,244
1,866
—
Table 3.14 (b): ATR-179—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #1 and One Year Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.012786
0.012786
-0.007345
0.002833
0.002833
-0.000657
52,244
1,866
—
A2-37
ATR-198—Enhanced Enforcement Period #1
Table 3.15 (a): ATR-198—Comparison of Speed Data from Enhanced Enforcement
Period #1 with Speed Data from Three Previous Years
Test Period
Decrease/Increase Decrease/Increase Decrease/Increase
as Compared to
as Compared to
as Compared to
Three Years
Two Years
One Year Earlier
Earlier
Earlier
(Three Weeks
(Five Weeks Only (One Week Only
Only—9/30 to
10/31/02 to
9/26/03 to
10/13 &
11/6/02)
10/30/03)
10/31 to 11/6)
Measure
(Three Weeks
Only
10/17/05 to
11/06/05)
Mean (mph)
57.40773211
-1.20813**
-1.08322**
-1.50988**
Percent in 10
mph pace
57.794813
-7.577**
-6.203**
-8.475*
0.072748526
-0.01344*
-0.02252*
-0.03222*
0.014130267
-0.00492*
-0.00717*
-0.00948*
0.002303474
-0.00149*
-0.00169*
-0.00239*
0.000636034
-0.00044*
-0.00077*
-0.00059*
0.000189091
ns
-0.00029*
ns
58,173
53,024
95,151
14,699
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.15 (b): ATR-198—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard
deviation (mph)
Median (mph)
15th percentile
(mph)
85th percentile
(mph)
90th percentile
(mph)
95th percentile
(mph)
Test Period
(Three Weeks Only
10/17/05 to 11/06/05)
9.20567*
59.18387353
52.06105237
63.95809376
64.63245386
66.94039589
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-38
Table 3.16 (a): ATR-198—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #1 and During the Previous Three
Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test
Period
(Three
Weeks
Only
10/17/05 to
11/06/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
4,232
206
-37
-62
-89
822
39
-14
-20
-26
58,173
2,770
—
—
—
Table 3.16 (b): ATR-198—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #1 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.072749
0.072749
-0.01344
-0.02252
-0.03222
0.014130
0.014130
-0.00492
-0.00717
-0.00948
58,173
2,770
—
—
—
Test Period
(Three
Weeks
Only
10/17/05 to
11/06/05)
A2-39
ATR-198—Regular Enforcement Period #1
Table 3.17 (a): ATR-198—Comparison of Speed Data from Regular Enforcement
Period #1 with Speed Data from One and Three Years Earliers
Measure
Test Period
(11/7/05 to12/4/05)
Decrease/Increase as
Compared to One
Year Earlier
Decrease/Increase as
Compared to Three
Years Earlier
Mean (mph)
55.70841
-2.44521**
-3.026258**
Percent in 10 mph
pace
50.3509
-0.12862**
+16.827**
0.054625
-0.023624*
-0.0338216**
0.010191
-0.006387*
-0.0092712**
0.001729
-0.001656*
-0.0016034*
0.000637
ns
-0.0003289*
0.000258
ns
ns
65,940
66,774
62,120
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.17 (b): ATR-198—Additional Speed Data from Regular Enforcement
Period #1
Measure
Standard
deviation (mph)
Median (mph)
15th percentile
(mph)
85th percentile
(mph)
th
90 percentile
(mph)
95th percentile
(mph)
Test Period
(11/7/05
to12/4/05)
10.37143*
58.02387
49.56881
63.46692
64.27064
65.52048
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-40
Table 3.18 (a): ATR-198—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #1 and One and Three Years Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(11/07/05
to
12/04/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
3,602
129
-56
-80
672
24
-15
-22
65,940
2,355
—
—
Table 3.18 (b): ATR-198—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #1 and One and Three Years Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
3,602
129
-56
-80
672
24
-15
-22
65,940
2,355
—
—
A2-41
ATR-199—Enhanced Enforcement Period #1
Table 3.19 (a): ATR-199—Comparison of Speed Data from Enhanced Enforcement
Period #1 with Speed Data from Three Previous Years
Decrease/
Increase as
Compared to Two
Years Earlier
Measure
Test Period
(9/26/05 to
11/6/05)
Decrease/Increase as
compared to One Year
Earlier
(Three Weeks Only
9/29/04 to 10/2/04, &
10/10/04 to 10/16/04, &
10/31/04 to 11/6/04)
Mean (mph)
58.851926
-0.595083**
0.712523**
-0.055154**
Percent in 10
mph pace
73.6447361
ns(-0.3717)
7.4151**
0.065224**
0.076170966
-0.023499*
-0.011692*
-0.0368**
0.023931465
-0.005538*
-0.003209*
-0.006403*
0.006797653
ns(-0.000784)
-0.002575*
-0.003626*
0.002824596
ns
ns
ns
0.000900146
ns
-0.000518*
ns
64,434
31,524
63,485
60,821
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Decrease/
Increase as
Compared to
Three Years
Earlier
(All Six Weeks)
(All Six Weeks)
Table 3.19 (b): ATR-199—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard
deviation (mph)
Median (mph)
15th percentile
(mph)
85th percentile
(mph)
90th percentile
(mph)
95th percentile
(mph)
Test Period
(9/26/05 to
11/6/05)
6.249016
58.8633878
55.1262884
63.83689487
64.62459658
67.50490196
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-42
Table 3.20 (a): ATR-199—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #1 and During the Previous Three
Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
4,908
117
-36
-18
-56
1,542
37
-8
-5
-10
64,434
1,534
—
—
—
Table 3.20 (b): ATR-199—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #1 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.076171
0.076171
-0.023499
-0.011692
-0.036800
0.023931
0.023931
-0.005538
-0.003209
-0.006403
64,434
1,534
—
—
—
A2-43
ATR-199—Regular Enforcement Period #1
Table 3.21 (a): ATR-199—Comparison of Speed Data from Regular Enforcement
Period #1 with Speed Data from Three Previous Years
Measure
Test Period
(Three Weeks Only
11/7/05 to 11/12/05
& 11/20/05
to 12/4/05)
Decrease/
Increase as
Compared to One
Year Earlier
(All Four Weeks)
Decrease/
Increase as
Compared to Two
Years Earlier
(All Four Weeks)
Decrease/
Increase as
Compared to Three
Years Earlier
(All Four Weeks)
Mean (mph)
57.55179463
-1.690556**
-0.163723**
-0.788973**
Percent in 10
mph pace
63.0479575
-10.4849**
-0.025341*
-0.046401*
0.064355073
-0.026491*
-0.015123*
-0.025368*
0.016275504
-0.009234*
-0.00837*
-0.010259*
0.004796163
-0.001854*
-0.004392*
-0.003972*
0.001965641
ns
-0.001169*
-0.000915*
0.000746943
ns
-0.000712*
ns
25,437
40,299
37,004
39,232
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.21 (b): ATR-199—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard
deviation (mph)
Median (mph)
15th percentile
(mph)
85th percentile
(mph)
90th percentile
(mph)
95th percentile
(mph)
Test Period
(Three Weeks Only
11/7/05 to 11/12/05 &
11/20/05 to 12/4/05)
7.55009*
58.29160637
52.20954106
63.5553382
64.39874005
66.49284546
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-44
Table 3.22 (a): ATR-199—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #1 and During the Previous Three Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test
Period
(Three
Weeks
Only
11/7/05 to
11/12/05 &
11/20/05 to
12/4/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
1,637
78
-32
-18
-31
414
20
-11
-10
-12
25,437
1,211
—
—
—
Table 3.20 (b): ATR-199—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #1 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(Three
Weeks
Only
11/7/05 to
11/12/05 &
11/20/05 to
12/4/05)
Daily
Average
in Test
Period
0.064355
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.064355
-0.026491
-0.015123
-0.025368
0.016276
0.016276
-0.009234
-0.00837
-0.010259
25,437
1,211
—
—
—
A2-45
ATR-222—Enhanced Enforcement Period #1
Table 3.23 (a): ATR-222—Comparison of Speed Data from Enhanced Enforcement
Period #1 with Speed Data from Three Previous Years
Measure
Test Period
(9/26/05 to
11/6/05)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
60.71465469
-1.17217**
-1.67022**
-1.67377**
Percent in 10
mph pace
57.2264985
-8.457**
-6.8797**
-6.727**
0.28266641
+0.043555**
ns (-0.00335)
+0.005406*
0.105630503
+0.037033**
+0.02694**
+0.021258*
0.037636798
+0.017106**
+0.012432*
+0.011194*
0.0120851
+0.007137*
+0.004804*
+0.00534*
0.005501964
+0.003615*
+0.002844*
+0.002734*
83,243
82,656
83,911
83,463
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.23 (b): ATR-222—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard
deviation (mph)
Median (mph)
15th percentile
(mph)
th
85 percentile
(mph)
90th percentile
(mph)
th
95 percentile
(mph)
Test Period
(9/26/05 to
11/6/05)
10.65382*
61.63626729
55.32474594
68.7468786
70.41404594
74.09085689
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-46
Table 3.24 (a): ATR-222—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #1 and During the Previous Three
Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
23,530
560
+86
-7
+11
8,793
209
+73
+53
+42
83,243
1,982
—
—
—
Table 3.24 (b): ATR-222—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #1 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(9/26/05 to
10/09/05)
0.282666
Daily
Average
in Test
Period
0.282666
Decrease/
Increase
Compared
to One Year
Earlier
0.105631
0.105631
+0.043555
+73
+0.037033
83,243
1,982
—
A2-47
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
-0.00335
+0.005406
+0.02694
+0.021258
—
—
ATR-222—Regular Enforcement Period #1
Table 3.25 (a): ATR-222—Comparison of Speed Data from Regular Enforcement
Period #1 with Speed Data from Three Previous Years
Measure
(Two Weeks
Only
11/7/05 to
11/20/05)
Decrease/
Increase as
Compared to
One Year
Earlier
(All Four Weeks
Decrease/
Increase as
Compared to Two
Years Earlier
(Two Weeks Only
11/7/03 to 11/20/03)
Decrease/
Increase as
Compared to
Three Years
Earlier
(All Four Weeks)
Mean (mph)
61.80513235
-0.36565**
-0.6012
-0.63361**
Percent in 10
mph pace
56.8505
-0.06237*
-0.07428*
-0.07227**
0.32288
+0.053089*
+0.045689*
+0.042902*
0.12126
+0.036048*
+0.038861*
+0.039953**
0.046845
+0.019761*
+0.022826*
+0.022082*
Test Period
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.015346
+0.008331*
+0.008363*
+0.009123*
0.0070120
+0.004109*
+0.004103*
+0.004864*
Vehicle Total
27,239
47,188
30,935
53,993
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.25 (b): ATR-222—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard
deviation (mph)
Median (mph)
15th percentile
(mph)
85th percentile
(mph)
th
90 percentile
(mph)
95th percentile
(mph)
Test Period
(Two Weeks Only
11/7/05 to 11/20/05)
10.19422*
62.4581138
56.12408439
69.2872815
71.42846571
74.78798717
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-48
Table 3.26 (a): ATR-222—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #1 and During the Previous Three Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test
Period
(Two
Weeks
Only
11/7/05 to
11/20/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
8,795
628
+103
+89
+83
3,303
236
+70
+76
+78
27,239
1,946
—
—
—
Table 3.26 (b): ATR-222—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #1 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.32288
0.32288
+0.053089
+0.045689
+0.042902
0.12126
0.12126
+0.036048
+0.038861
+0.039953
27,239
1,946
—
—
—
Test Period
(Two
Weeks
Only
11/7/05 to
11/20/05)
3.3. Overall Effect of the MSMP on 2-Lane/2-Way Highways
In the MSMP, we obtained speed data from seven ATRs located on 2-Lane/2-Way
Highways—three of these ATRs were located Within Enhanced Enforcement Zones,
while the remaining four were located Outside Enhanced Enforcement Zones. The speed
limit was increased from 55 mph to 60 mph at the locations of the three ATRs Within
Enhanced Enforcement Zones, while the speed limit remained unchanged at 55 mph at
the locations of the four ATRs Outside Enhanced Enforcement Zones.
In order to provide a brief overall summary of the effect of the MSMP, speed data from
the three ATRs Within Enhanced Enforcement Zones were combined. For this summary,
we focused on drivers traveling at least 10 mph above the new speed limit. Then, we
compared speed data from the Test Year with data from the previous year, when the
A2-49
speed limit at the locations of the three ATRs was still 55 mph. Table 3.27 shows the
results of this comparison for the First Enhanced Enforcement Period.
Table 3.27: Effect of MSMP on 2-Lane/2-Way Highways during the First Enhanced
Enforcement Period at Three ATRs Within Enhanced Enforcement Zones
Sample Total
288,067
Sample Total
275,520
One Year Before MSMP
# Over 70 mph
15,176
First Enhanced Enforcement Period
# Over 70 mph
8,787
% Over 70 mph
5.26
% Over 70 mph
3.19
Result: 39.35% Decrease in Drivers Traveling Over 70 mph
Table 3.27 indicates that, for the three ATRs located on 2-Lane/2-Way Highways Within
Enhanced Enforcement Zones, during the First Enhanced Enforcement Period, there was
a 39.35% decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the
new speed limit.
A similar comparison was conducted for the First Regular Enforcement Period.
However, in this case, we were only able to combine data from two of the ATRs—as no
speed data were available from ATR-210 for this time period. The results of this
comparison using speed data from ATR-219 and ATR-220 are shown in Table 3.28.
Table 3.28: Effect of MSMP on 2-Lane/2-Way Highways during First Regular
Enforcement Period at Two ATRs (ATR-219 and ATR-220) Within Enhanced
Enforcement Zones
Sample Total
131,850
Sample Total
120,639
One Year Before MSMP
# Over 70 mph
5,619
First Regular Enforcement Period
# Over 70 mph
3,034
% Over 70 mph
4.26
% Over 70 mph
2.51
Result: 41.08% Decrease in Drivers Traveling Over 70 mph
Table 3.28 shows that, for two ATRs located on 2-Lane/2-Way Highways Within
Enhanced Enforcement Zones, during the First Regular Enforcement Period, there was a
41.08% reduction in the number of drivers traveling over 70 mph—i.e., 10 mph over the
speed limit.
We also examined the difference between the speed data obtained during the Test Periods
from the four ATRs Outside Enhanced Enforcement Zones, where there was no change
A2-50
in the level of enforcement during the MSMP and no change in the speed limit. For
comparison purposes, we focused on drivers traveling at 70 mph or more—while this is
10 mph above the new speed limit Within Enhanced Enforcement Zones, it is 15 mph
above the actual speed limit at the locations of the four ATRs Outside Enhanced
Enforcement Zones. The results of this comparison for speed data obtained during the
First Enhanced Enforcement Period are shown in Table 3.29.
Table 3.29: Effect of MSMP on 2-Lane/2-Way Highways during the First Enhanced
Enforcement Period at Four ATRs Outside Enhanced Enforcement Zones
Sample Total
338,722**
Sample Total
352,459*
One Year Before MSMP
# Over 70 mph
9,902**
First Enhanced Enforcement Period
# Over 70 mph
12,279*
% Over 70 mph
2.92**
% Over 70 mph
3.48*
Result: 19.17 % Increase in Drivers Traveling Over 70 mph
**Numbers adjusted to account for limited availability of data from ATR-198 and ATR-199 during the
time period
*Numbers adjusted to account for limited availability of data from ATR-198 during the time period
Table 3.29 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on 2-Lane/2-Way Highways, during the First Enhanced Enforcement Period, there was a
19.17% increase in the number of drivers traveling over 70 mph—i.e., 10 mph above the
new speed limit Within Enhanced Enforcement Zones (and 15 mph above the current
speed limit Outside the Enhanced Enforcement Zones).
A similar comparison was conducted for the First Regular Enforcement Period. The
results of this comparison using speed data from the four ATRs located Outside
Enhanced Enforcement Zones are shown in Table 3.30.
Table 3.30: Effect of MSMP on 2-Lane/2-Way Highways during First Regular
Enforcement Period at Four ATRs Outside Enhanced Enforcement Zones
Sample Total
208,703
Sample Total
206,578*
One Year Before MSMP
# Over 70 mph
6,346
First Regular Enforcement Period
# Over 70 mph
7,978*
% Over 70 mph
3.04
% Over 70 mph
3.86*
Result—26.97% Decrease in Drivers over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-199 and ATR-222 during the time
period
A2-51
Table 3.30 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on the 2-Lane/2-Way Highways, during the first Regular Enforcement Period there was
virtually a 26.97% increase in the number of drivers traveling over 70 mph—i.e., at 10
mph over the new speed limit Within Enhanced Enforcement Zones (and 15 mph above
the current speed limit Outside Enhanced Enforcement Zones).
Comparisons between speed data from the ATRs located Within Enhanced Enforcement
Zones and the ATRs located Outside Enhanced Enforcement Zones should be treated
with caution. For example, it should be noted that the three ATRs located Within
Enhanced Enforcement Zones are all in Northern Minnesota, and that the proportion of
vehicles traveling at 70 mph or more ranges between 0.021 and 0.052 for these ATRs. In
contrast, the four ATRs located Outside Enhanced Enforcement Zones are more widely
spread, with three in South Western Minnesota and one in East Central Minnesota. For
these four ATRs, the there is a much greater range in the proportion of vehicles traveling
at 70 mph or more—the proportion varies between 0.0028, for ATR-179—one of the
three ATRs in South Western Minnesota—and 0.1213 for ATR-222—which is located in
East Central Minnesota.
A2-52
Section 4. Speed Data Obtained on 4-Lane Divided Highways
We obtained speed data from five ATRs that were located on 4-Lane Divided Highways.
Four of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining ATR was located Outside the Enhanced Enforcement Zones. At the locations
of the four ATRs Within the Enhanced Enforcement Zones and the ATRs Outside the
Enhanced Enforcement Zones, the speed limit was unchanged—remaining at 65mph—
during the MSMP.
For the ATRs located Within Enhanced Enforcement Zones and the ATR located Outside
Enhanced Enforcement Zones on 4-Lane Divided Highways, we present comparisons of
the speed data obtained during the Test Year with the speed data obtained at those same
ATRs in the three years prior to the MSMP. Comparisons using the speed data from the
ATRs located Within Enhanced Enforcement Zones are presented first. Then, we present
comparisons using the speed data from the ATR located Outside the Enhanced
Enforcement Zones.
In making the comparisons between the speed data obtained during the Test Year and the
speed data obtained prior to the MSMP, we used two statistical tests. The first test was
used to examine differences in the mean speeds—for this we used the procedure for
comparing population means outlined by Kitchens (1987, p 369-373). The second test
was used to explore differences in the percentage of vehicles in the 10 mph pace and in
the differences in the proportions of vehicle traveling at various speeds. For this test, we
treated the distribution of speeds as a Bernoulli population—i.e., a population in which
each element is one of two possibilities, in this case, (1) in or out of the 10 mph pace, or
(2) above or below a selected speed (e.g., 75 mph). We then used the procedure for
comparing population proportions described by Kitchens (1987, pages 400-404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
ATR in the time periods under consideration. Second, the tests were conducted using an
extremely conservative correction, with n-values equal to the number of hours in each
test period—the rationale for this was that it is possible, when traffic is congested, that
individual vehicles may travel at speeds which are not independent of each other.
4.1. Speed Data from the ATRs located Within Enhanced Enforcement Zones
The four ATRs located Within Enhanced Enforcement Zones on 4-Lane Divided
Highways were as follows; (1) ATR-172,on US-10, near Dilworth, in Clay County, (2)
ATR-187, on US-10, near Rice, in Benton County, (3) ATR-188, on US-52, North of
Rochester, in Olmstead County, and (4) ATR-197, on SR-60, West of SR-4, in
Watonwan County. At these four sites, the speed limit remained unchanged at 65 mph.
The effect of the MSMP on the speed data at each of these four ATRs is reported in this
A2-53
section. It is reported ATR by ATR—with the effect of the MSMP in the first Enhanced
Enforcement Period followed by its effect in the first Regular Enhancement Period.
For each of the four ATRs Within Enhanced Enforcement Zones, two tables are presented
for each time period. In the first of these tables speed data from the Test Year is
compared with the available historical speed data. Where possible speed data from the
three years prior to the MSMP are included in this table—however, in some cases data
are only available from one or two of the prior years. Also in some cases, speed data are
not available from the whole of the First Enhanced Enforcement Period or the First
Regular Enhancement Period—in these cases the dates from which the data are available
are noted in the table. In the second of the tables for each ATR, the focus is on drivers
traveling at least 5 mph and at least 10 mph above the speed limit adopted for the
MSMP—i.e., on drivers traveling at 70 mph or more and at 75 mph or more. In this
second table, we present the number (and proportion) of vehicles traveling above these
speeds throughout the First Enhanced Enforcement Period or the First Regular
Enhancement Period. We also present the average number of vehicles traveling above
these speeds every day. Then, the table presents the decrease in the number of vehicles
relative to the number that were traveling at these speeds before the MSMP.
A2-54
ATR-172—Enhanced Enforcement Period #1
Table 4.1 (a): ATR-172—Comparison of Speed Data from Enhanced Enforcement
Period #1 with Speed Data from One Year Earlier
Measure
Test Period
(9/26/05 to 11/6/05)
Decrease/
Increase
Compared to
One Year Earlier
Mean (mph)
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
65.84339
6.444001
66.56657
61.16661
70.89026
72.42022
73.95017
-0.65048**
—
—
—
—
—
—
Percent in 10 mph pace
71.5634
+1.9338*
0.646419
-0.04461**
0.179094
-0.03600**
0.015691
-0.00452*
0.003266
-0.00038*
0.001180
0.000121*
631,126
649,180
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
Table 4.1 (b): ATR-172—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(9/26/05 to 11/6/05)
6.44400*
66.56657
61.16661
70.89026
72.42022
73.95017
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-55
Table 4.2 (a): ATR-172—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65
mph) During Enhanced Enforcement Period #1 and One Year Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Test Period
(9/26/05 to
10/09/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
113,031
2,691
-541
9,903
236
-68
631,126
15,027
—
Table 4.2 (b): ATR-172—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Enhanced Enforcement Period #1 and One Year Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(9/26/05 to
10/09/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.179094
0.179094
-0.03600)
0.015691
0.015691
-0.00452
631,126
15,027
—
A2-56
ATR-172—Regular Enforcement Period #1
Table 4.3 (a): ATR-172—Comparison of Speed Data from Regular Enforcement
Period #1 with Speed Data from One Year Earlier
Measure
Test Period
(11/07/05 to
12/04/05)
Decrease/Increase
Compared to One
Year Earlier
Mean (mph)
64.24307
-2.31666**
Percent in 10 mph pace
63.5323
-5.604**
0.544463
-0.15096**
0.143322
-0.08057**
0.01191
-0.00867*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.002174
-0.00183*
0.0006834
-0.00051*
Vehicle Total
357,014
395,218
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.3 (b): ATR-172—Additional Speed Data from Regular Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(11/07/05 to
12/04/05)
7.51102*
65.55421
58.70125
69.91676
71.64833
73.55074
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-57
Table 4.4 (a): ATR-172—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65
mph) During Regular Enforcement Period #1 and One Year Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
51,168
1,827
-1,027
4,252
152
-111
357,014
12,751
—
Table 4.4 (b): ATR-172—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Regular Enforcement Period #1 and One Year Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.143322
0.143322
-0.08057
0.011910
0.011910
-0.00867
357,014
12,751
—
A2-58
ATR-187—Enhanced Enforcement Period #1
Table 4.5 (a): ATR-187—Comparison of Speed Data from Enhanced Enforcement
Period #1 with Speed Data from Three Previous Years
Measure
Test Period
(9/26/05 to
11/6/05)
Decrease/
Increase
Compared to
One Year
Earlier
(Two Weeks
Only)
(9/26/04 to
10/9/04)
Mean (mph)
66.85712
-2.82288**
-2.53045**
-2.04073**
Percent in 10 mph
pace
61.1284
-12.419**
-9.651**
-5.2874**
0.718382
-0.13639**
-0.11909**
-0.09216**
0.320276
-0.17946**
-0.16182**
-0.08693**
0.064743
-0.03664**
-0.03315**
-0.04783**
0.015448
-0.00479*
-0.00448*
-0.01668**
0.002619
-0.000323*
-0.00057*
-0.00267*
867,738
302,502
844,339
815,598
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
Decrease/
Increase
Compared to
Two Years
Earlier
Decrease/
Increase
Compared to
Three Years
Earlier
(All Six
Weeks)
(All Six
Weeks)
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.5 (b): ATR-187—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(9/26/05 to
11/6/05)
8.31172*
67.74276
61.50232
73.33178
74.31013
76.49539
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-59
Table 4.6 (a): ATR-187—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65
mph) During Enhanced Enforcement Period #1 and During the Previous Three
Years
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
277,916
6,617
-3,708
-3,343
-1,796
56,180
1,338
-757
-685
-988
867,738
20,660
—
—
—
Table 4.6 (b): ATR-187—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Enhanced Enforcement Period #1 and During the Previous Three Years
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.320276
0.320276
-0.17946
-0.16182
-0.08693
0.064743
0.064743
-0.03664
-0.03315
-0.04783
867,738
20,660
—
—
—
A2-60
ATR-187—Regular Enforcement Period #1
Table 4.7 (a): ATR-187—Comparison of Speed Data from Regular Enforcement
Period #1 with Speed Data from Three Previous Years
Measure
Test Period
(11/07/05 to
12/04/05)
Decrease/Increase
Compared to
One Year Earlier
Decrease/Increase
Compared to
Two Years Earlier
Decrease/Increase
Compared to
Three Years
Earlier
Mean (mph)
67.33856
-2.14892**
-1.84169**
-1.91284**
Percent in 10
mph pace
60.4759
-11.429**
-9.243**
-0.06219**
0.714927
-0.13162**
-0.11292**
-0.09324**
0.339603
-0.15905*
-0.12597**
-0.09963**
0.075616
-0.02292*
-0.01506*
-0.04071**
0.016371
ns
+0.000592*
-0.00962*
0.003088
+0.00074*
+0.000918*
-0.00093*
499,669
495,957
511,960
517,738
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.7 (b): ATR-187—Additional Speed Data from Regular Enforcement
Period #1
Measure
Standard
deviation (mph)
Median (mph)
15th percentile
(mph)
th
85 percentile
(mph)
90th percentile
(mph)
th
95 percentile
(mph)
Test Period
(11/07/05 to
12/04/05)
7.44965*
67.86322
61.60747
73.59114
74.53816
77.16187
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-61
Table 4.8 (a): ATR-187—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65
mph) During Regular Enforcement Period #1 and During the Previous Three Years
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
169,689
7,409
-2,838
-2,248
37,783
1,349
-409
-269
-1,778
-458
499,669
17,845
—
—
Test
Period
(11/07/05
to
12/04/05)
—
Table 4.8 (b): ATR-187—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Regular Enforcement Period #1 and During the Previous Three Years
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.339603
0.339603
-0.15905
-0.12597
-0.09963
0.075616
0.075616
-0.02292
-0.01506
-0.04071
499,669
17,845
—
—
—
A2-62
ATR-188—Enhanced Enforcement Period #1
Table 4.9 (a): ATR-188—Comparison of Speed Data from Enhanced Enforcement
Period #1 with Speed Data from One and Three Years Earlier
Decrease/Increase
Compared to
Three Years
Earlier
(Two Weeks Only
9/26/02 to 10/9/02)
Measure
Test Period
(9/26/05 to 11/6/05)
Decrease/
Increase
Compared to
One Year
Earlier
(All Six Weeks)
Mean (mph)
67.25068
+2.7003864**
+1.370540192**
Percent in 10 mph pace
59.5264
+9.7142241**
ns
0.686093
+0.129429184**
+0.081607893**
0.331422
+0.058427762**
+0.087972263**
0.080797
+0.013840974*
+0.023396608*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.008973
+0.001081868*
-0.011583414*
0.001895
ns
-0.005468*
Vehicle Total
1,235,082
1,238,782
383,098
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.9 (b): ATR-188—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(9/26/05 to 11/6/05)
6.99324*
67.62346
61.47329
73.61939
74.6169
77.14391
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-63
Table 4.10 (a): ATR-188—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65
mph) During Enhanced Enforcement Period #1 and One and Three Years Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
409,333
9,746
+1,718
+2587
99,791
2,376
+407
+688
1,235,082
29,407
—
—
Table 4.10 (b): ATR-188—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Enhanced Enforcement Period #1 and One and Three Years Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.331422
0.331422
+0.058428
+0.087972
0.080797
0.080797
+0.013841
+0.023397
1,235,082
29,407
—
—
A2-64
ATR-188—Regular Enforcement Period #1
Table 4.11 (a): ATR-188—Comparison of Speed Data from Regular Enforcement
Period #1 with Speed Data from One and Three Years Earlier
(All Four Weeks)
Decrease/Increase
Compared to
Three Years Earlier
(Two Weeks Only
11/14/02 to 11/27/02)
66.33459
+0.385291**
+0.823166**
57.1597
+1.4748*
-5.626*
0.640717
+0.019794*
+0.054764*
0.299467
-0.00164*
+0.089262**
0.070606
-0.00267*
+0.02402*
Measure
Test Period
(11/07/05 to
12/04/05)
Mean (mph)
Percent in 10 mph pace
Decrease/Increase
Compared to
One Year Earlier
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.007879
-0.00058*
-0.00863*
0.001716
ns
-0.00525*
Vehicle Total
783,067
802,496
391,921
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.11 (b): ATR-188—Additional Speed Data from Regular Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(11/07/05 to
12/04/05)
7.70161*
67.06179
60.46789
73.26545
74.35782
76.64251
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-65
Table 4.12 (a): ATR-188—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65
mph) During Regular Enforcement Period #1 and One and Three Years Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
234,503
8,375
-46
+2,496
55,289
1,975
-75
+672
783,067
27,967
—
—
Test
Period
(11/07/05
to
12/04/05)
Table 4.12 (b): ATR-188—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Regular Enforcement Period #1 and One and Three Years Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(11/07/05 to
12/04/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.299467
(0.299467)
-0.00164
+0.089262
0.07061
0.07061
-0.00267
+0.02402
783,067
27,967
—
—
A2-66
ATR-197—Enhanced Enforcement Period #1
Table 4.13: ATR-197—Comparison of Speed Data from Enhanced Enforcement
Period #1 with Speed Data from the Previous Two Years
Measure
Test Period
(9/26/05 to 11/6/05)
(All Six Weeks)
Decrease/Increase
Compared to
Two Years Earlier
(Two Weeks Only)
(9/26/04 to 10/9/04)
Mean (mph)
65.08723
-0.99269**
-0.15146**
Percent in 10 mph pace
67.5675
+1.2668*
+0.042377*
0.564961
-0.07234**
-0.02573*
0.180133
-0.04323**
-0.03802*
0.020928
-0.00804*
-0.01199*
Decrease/Increase
Compared to
One Year Earlier
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.004972
-0.00183*
-0.00419*
0.001363
ns
-0.00141*
Vehicle Total
198,104
205,637
66,718
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.13 (b): ATR-197—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(9/26/05 to 11/6/05)
6.90683*
65.84402
60.13891
70.94635
72.51666
74.08697
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-67
Table 4.14 (a): ATR-197—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65
mph) During Enhanced Enforcement Period #1 and During the Previous Two Years
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test
Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
35,685
850
-204
179
4,146
99
-38
-57
198,104
4,717
—
—
Table 4.14 (b): ATR-197—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Enhanced Enforcement Period #1 and During the Previous Two Years
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.18013
0.18013
-0.04323
-0.03802
0.02093
0.02093
-0.00804
-0.01199
198,104
4,717
—
—
A2-68
ATR-197—Regular Enforcement Period #1
Table 4.15 (a): ATR-197—Comparison of Speed Data from Regular Enforcement
Period #1 with Speed Data from the One Year Earlier (for the 9/26/04 to 11/6/04
Time Period)
Decrease/Increase
Compared to
One Year Earlier
Measure
Test Period
(11/07/05 to
12/04/05)
(9/26/04 to 11/6/04)
Mean (mph)
64.33675
-1.74316**
Percent in 10 mph pace
63.1549
-3.1458*
0.518121
-0.119177**
0.161334
-0.06203**
0.017749
-0.011215*
0.003921
-0.002877*
0.000948
-0.000589*
123,446
205,637
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.15 (b): ATR-197—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(11/07/05 to
12/04/05)
7.41892*
65.25395
58.86595
70.39467
72.1358
73.87693
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-69
Table 4.16 (a): ATR-197—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65
mph) During Regular Enforcement Period #1 with Speed Data from One Year
Earlier (for the 9/26/04 to 11/6/04 Time Period)
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
19,916
711
-273
2,191
78
-49
123,446
4,409
Table 4.16 (b): ATR-197—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Regular Enforcement Period #1 with Speed Data from One Year Earlier (for the
9/26/04 to 11/6/04 Time Period)
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.16133
0.16133
-0.06203
0.01775
0.01775
-0.011215
123,446
4,409
4.2. Speed Data from One ATR located Outside Enhanced Enforcement Zones
There was one ATR located on a 4-Lane Divide Highway Outside the Enhanced
Enforcement Zones. It was ATR-353, on MNTH-169 near Jordan in Scott County.
There were no changes in enforcement at this location. For this ATR, the speed data
obtained during 2005, when the MSMP occurred, was compared with historical speed
data. Comparisons are presented for the six-week time period between 9/26 and 11/6,
when the First Enhanced Enforcement Period occurred during the MSMP, and then for
the four-week time period between 11/7 and 12/4, when the First Regular Enhancement
Period occurred.
Two tables are presented for each of these time periods. In the first table, speed data
from the Test Year is compared with historical speed data. Speed data was only available
for the two years prior to the MSMP for ATR-353. In the second of the two tables, the
focus is on drivers who were traveling at least 5 mph and at least 10 mph above the speed
limit—i.e., drivers traveling at 70 mph or more and at 75 mph or more. In this second
table, we present the number (and proportion) of vehicles traveling above these speeds
throughout the First Enhanced Enforcement Period or the First Regular Enhancement
A2-70
Period. We also present the average number of vehicles traveling above these speeds
every day. Then, the table presents the decrease in the number of vehicles relative to the
number that were traveling at these speeds in the two years prior to the implementation of
the MSMP.
ATR-353—Enhanced Enforcement Period #1
Table 4.17 (a): ATR-353—Comparison of Speed Data from Enhanced Enforcement
Period #1 with Speed Data from the Two Prior Years
Measure
Test Period
(9/26/05 to 11/6/05)
Decrease/Increase
Compared to
One Year Earlier
Decrease/Increase
Compared to
Two Years Earlier
Mean (mph)
67.387564
-0.58224**
-0.61774**
Percent in 10 mph pace
66.00213
-0.9655*
-0.54445*
0.7416016
-0.04242**
-0.03569*
0.3216334
-0.05554**
-0.05673**
0.0350131
-0.01283*
-0.01346*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.0044905
-0.00206*
-0.00246*
0.00072128
-0.00026*
-0.0004*
Vehicle Total
958,013
980,861
952,971
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.17 (b): ATR-353—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(9/26/05 to 11/6/05)
6.27442*
67.876428
62.255657
72.99409
73.866324
74.738558
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-71
Table 4.18 (a): ATR-353—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65
mph) During Enhanced Enforcement Period #1 and During the Previous Two Years
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test
Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
308,129
7,336
-1,232
-1,258
33,543
799
-285
-298
958,013
22,810
—
—
Table 4.18 (b): ATR-353—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Enhanced Enforcement Period #1 and During the Previous Two Years
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.321633
0.321633
-0.05554
-0.05673
0.035013
0.035013
-0.01283
-0.01346
958,013
22,810
—
—
A2-72
ATR-353—Regular Enforcement Period #1
Table 4.19 (a): ATR-353—Comparison of Speed Data from Regular Enforcement
Period #1 with Speed Data from Two Years Earlier
Measure
Test Period
(11/07/05 to
12/04/05)
Decrease/Increase
Compared to
One Year Earlier
Decrease/Increase
Compared to
Two Years Earlier
Mean (mph)
66.07671
-2.28402**
-1.56129**
Percent in 10 mph pace
62.39461
-6.5561**
-2.65313*
0.660573
-0.13849**
-0.09279**
0.2628058
-0.13443**
-0.0912**
0.0259699
-0.02208**
-0.01497*
0.0032494
-0.00301*
-0.00202*
0.0004754
-0.00047*
-0.00030882*
589,028
619,067
578,950
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.19 (b): ATR-353—Additional Speed Data from Regular Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(11/07/05 to
12/04/05)
7.14740*
67.01843
60.757595
72.381519
73.437102
74.492685
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-73
Table 4.20 (a): ATR-353—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65
mph) During Regular Enforcement Period #1 and During the Previous Two Years
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
154,800
5,529
-2,828
-1,919
15,297
546
-464
-315
589,028
21,037
—
—
Test
Period
(11/07/05
to
12/04/05)
Table 4.20 (b): ATR-353—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Regular Enforcement Period #1 and During the Previous Two Years
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
0.262806
0.262806
-0.13443
-0.09120
0.025970
0.025970
-0.02208
-0.01497
589,028
21,037
—
—
4.3. Overall Effect of the MSMP on 4-Lane Divided Highways
In the MSMP, we obtained speed data from five ATRs located on 4-Lane Divided
Highways. Four of these ATRs were located Within Enhanced Enforcement Zones, while
the fifth was located Outside the Enhanced Enforcement Zones. At the locations of the
four ATRs Within the Enhanced Enforcement Zones and the ATRs Outside the Enhanced
Enforcement Zones, the speed limit was unchanged—at 65mph—during the MSMP.
In order to provide a brief overall summary of the effect of the MSMP, speed data from
the four ATRs Within Enhanced Enforcement Zones were combined. For this summary,
we focused on drivers traveling at least 10 mph above the speed limit—i.e., on drivers
traveling at 75 mph or more. Then, we compared speed data from the Test Year with
data from the previous year. Table 4.21 shows the results of this comparison for the first
Enhanced Enforcement Period.
A2-74
Table 4.21: Effect of MSMP on 4-Lane Divided Highways during the First
Enhanced Enforcement Period at Four ATRs Within Enhanced Enforcement Zones
Sample Total
3,001,105*
Sample Total
2,932,050
One Year Before MSMP
# Over 75 mph
194,025*
First Enhanced Enforcement Period
# Over 75 mph
170,020
% Over 75 mph
6.47*
% Over 75 mph
5.80
Result: 10.36% Decrease in Drivers Traveling Over 75 mph
*Numbers adjusted to account for limited availability of data from ATR-187
Table 4.21 indicates that, for the four ATRs located Within Enhanced Enforcement Zones
on 4-Way Divided Highways, during the First Enhanced Enforcement Period, there was a
10.36% decrease in the number of drivers traveling at 75 mph or more—i.e., 10 mph or
more over the speed limit.
A similar comparison was conducted for the First Regular Enforcement Period. The
results of this comparison are shown in Table 4.22.
Table 4.22: Effect of MSMP on 4-Lane Divided Highways during First Regular
Enforcement Period at Four ATRs Within Enhanced Enforcement Zones
Sample Total
1,830,762*
Sample Total
1,763,196
One Year Before MSMP
# Over 75 mph
119,779*
First Regular Enforcement Period
# Over 75 mph
99,515
% Over 75 mph
6.54*
% Over 75 mph
5.64
Result—13.76% Decrease in Drivers Traveling Over 75 mph
*Numbers adjusted because, for ATR-197, comparison data were from a 6-week time period.
As Table 4.22 shows, for the four ATRs Within Enhanced Enforcement Zones on 4-Way
Divided Highways, during the first Regular Enforcement Period, there was a 13.76%
reduction in drivers traveling over 75 mph—i.e., 10 mph above the speed limit.
We also examined the difference between the speed data obtained during the Test Periods
from the single ATR Outside the Enhanced Enforcement Zones. For comparison
purposes, we again focused on drivers traveling at 75 mph or more—10 mph above the
speed limit. The results of this comparison for speed data obtained during the First
Enhanced Enforcement Period are shown in Table 4.23.
A2-75
Table 4.23: Effect of MSMP at one ATR Outside the Enhanced Enforcement Zones
on a 4-Way Divided Highway During the First Enhanced Enforcement Period
Sample Total
980,861
Sample Total
958,013
One Year Before MSMP
# Over 75 mph
46,929
First Enhanced Enforcement Period
# Over 75 mph
33,543
% Over 75 mph
4.78
% Over 75 mph
3.50
Result: 26.78% Decrease in Drivers Traveling Over 75 mph
Table 4.23 shows that, for the single ATR located Outside the Enhanced Enforcement
Zones on a 4-Way Divided Highway, during the First Enhanced Enforcement Period,
there was a 26.78% decrease in the number of drivers traveling over 75 mph—i.e., 10
mph or more above the speed limit.
A similar comparison was conducted for the First Regular Enforcement Period. The
results of this comparison are shown in Table 4.24.
Table 4.24: Effect of MSMP at one ATR Outside the Enhanced Enforcement Zones
on a 4-Way Divided Highway During the First Regular Enforcement Period
Sample Total
619,067
Sample Total
589,028
One Year Before MSMP
# Over 75 mph
29,749
First Regular Enforcement Period
# Over 75 mph
15,247
% Over 75 mph
4.81
% Over 75 mph
2.59
Result—46.15% Decrease in Drivers over 75 mph
Table 4.24 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
a 4-Way Divided Highway, during the first Regular Enforcement Period there was a
46.15% decrease in the number of drivers traveling over 75 mph—i.e., at 10 mph over
the speed limit.
Comparisons between speed data from the ATRs located Within Enhanced Enforcement
Zones and the ATR located Outside the Enhanced Enforcement Zones should be treated
with caution. The four ATRs located Within Enhanced Enforcement Zones are scattered
throughout Minnesota; while the single ATR Outside the Enhanced Enforcement Zones
is located a few miles to the South-West of the Twin Cities—many of the drivers
traveling past this ATR may have traveled through Enhanced Enforcement Zones in the
Cities.
A2-76
Section 5. Speed Data Obtained on Rural Freeways
We obtained speed data from five ATRs located on Rural Freeways. Four of these ATRs
were located Within Enhanced Enforcement Zones, while the remaining ATR was located
Outside the Enhanced Enforcement Zones. At all five ATR locations, the speed limit was
unchanged—at 70 mph—during the MSMP.
In this section of the report, for the ATRs located Within Enhanced Enforcement Zones
and the single ATR located Outside the Enhanced Enforcement Zones, we present
comparisons of the speed data obtained during the Test Year with speed data obtained at
those same ATRs prior to the MSMP. Comparisons using the speed data from the ATRs
located Within Enhanced Enforcement Zones are presented first. Then, we present
comparisons using the speed data from the ATR located Outside the Enhanced
Enforcement Zones.
In making the comparisons between the speed data obtained during the Test Year and the
speed data obtained prior to the MSMP, we used two statistical tests. The first test was
used to examine differences in the mean speeds—for this we used the procedure for
comparing population means outlined by Kitchens (1987, p 369-373). The second test
was used to explore differences in the percentage of vehicles in the 10 mph pace and in
the differences in the proportions of vehicle traveling at various speeds. For this test, we
treated the distribution of speeds as a Bernoulli population—i.e., a population in which
each element is one of two possibilities, in this case, (1) in or out of the 10 mph pace, or
(2) above or below a selected speed (e.g., 75 mph). We then used the procedure for
comparing population proportions described by Kitchens (1987, pages 400-404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
ATR in the time periods under consideration. Second, the tests were conducted using an
extremely conservative correction, using n-values equal to the number of hours in each
test period—the rationale for this was that it is possible, when traffic is congested, that
individual vehicles may travel at speeds which are not independent of each other.
5.1. Speed Data from ATRs located Within Enhanced Enforcement Zones
The four ATRs located Within Enhanced Enforcement Zones on Rural Freeways were as
follows: (1) ATR-175, on I-94, near Saulk Centre in Stearns County, (2) ATR-191, on I35, near Wyoming, in Chisago County, (3) ATR-208, on I-35, near Owatanna in Steele
County, and (4) ATR-227, on I-90, near Alden in Freeborn County. During the MSMP,
there was no change in the speed limit—it remained at 70 mph—at the locations of these
four ATRs. The effect of the MSMP on the speed data at each of these four ATRs is
reported in this section. It is reported ATR by ATR—with the effect of the MSMP in the
First Enhanced Enforcement Period followed by its effect in the First Regular
Enhancement Period.
A2-77
For each of the four ATRs Within Enhanced Enforcement Zones, two tables are presented
for each time period. In the first of these tables, speed data from the Test Year are
compared with the available historical speed data. Where possible speed data from the
three years prior to the MSMP are included in this table—however, in some cases data
are only available from one or two of the prior years. Also in some cases, speed data are
not available from the whole of the First Enhanced Enforcement Period or the First
Regular Enhancement Period—in these cases the dates from which the data are available
are noted in the table. In the second of the two tables for each ATR, the focus is on
drivers traveling at least 5 mph and at least 10 mph above the speed limit—i.e., on drivers
traveling at 75 mph or more and at 80 mph or more. In this second table, we present the
number (and proportion) of vehicles traveling above these speeds throughout the sixweek Enhanced Enforcement Period or the four-week Regular Enhancement Period. We
also present the average number of vehicles traveling above these speeds every day.
Then, the table presents the decrease in the number of vehicles relative to the number that
were traveling at these speeds before the MSMP.
A2-78
ATR-175—Enhanced Enforcement Period #1
Table 5.1 (a): ATR-175—Comparison of Speed Data from Enhanced Enforcement
Period #1 with Speed Data from the Three Previous Years
Decrease/Increase
Compared To
Three Years Earlier
(All Six Weeks)
Decrease/Increase
Compared To
Two Years
Earlier
(Four Weeks Only
10/10/05 to 11/6/05)
72.61958416
-0.70742**
-0.38945**
+1.756667**
50.8811471
-13.0982**
-9.2213**
-0.04152*
0.864840152
-0.05932**
-0.03154*
+0.043502
0.654677511
-0.12154**
-0.10304**
+0.087283**
0.354011726
-0.03471*
-0.03943*
+0.095338**
0.147698846
+0.063748**
+0.055907**
+0.071527**
0.050452126
+0.038803**
+0.036786**
+0.032993**
384,959
925,398
616,708
311,006
Decrease/Increase
Compared To
One Year Earlier
Measure
Test Period
(Four Weeks
Only
10/10/05 to
11/6/05)
Mean (mph)
Percent in 10
mph pace
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
(Two Weeks Only
9/26/02 to 10/9/02)
Table 5.1 (b): ATR-175—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Four Weeks Only
10/10/05 to 11/6/05)
8.40788*
72.57224997
65.35306351
79.94423145
82.45246554
90.04552469
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-79
Table 5.2 (a): ATR-175—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70
mph) During Enhanced Enforcement Period #1 and During the Previous Three
Years
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Test
Period
(Four
Weeks
Only
10/10/05 to
11/6/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
136,280
4,867
-477
-542
+1,311
56,858
2,031
+876
+769
+983
384,959
13,749
—
—
—
Table 5.2 (b): ATR-175—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70 mph) During
Enhanced Enforcement Period #1 and During the Previous Three Years
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.354012
0.354012
-0.034710
-0.03943
+0.095338
0.147699
0.147699
+0.063748
+0.055907
+0.071527
Test Period
(Four
Weeks
Only
10/10/05 to
11/6/05)
A2-80
ATR-175—Regular Enforcement Period #1
Table 5.3 (a): ATR-175—Comparison of Speed Data from Regular Enforcement
Period #1 with Speed Data from the Three Previous Years
(All Four Weeks)
(All Four Weeks)
Decrease/Increase
Compared to
Three Years
Earlier
(Two Weeks Only
11/7/02 to
11/20/02)
69.98035504
-3.14503**
-2.68304**
-1.02691**
62.9258456
-0.279*
+2.7751*
+8.759**
0.818248309
-0.09962**
-0.07478**
-0.00358*
0.58895913
-0.17595**
-0.1533**
+0.012286*
0.187871214
-0.18942**
-0.1758**
-0.08041**
0.025996031
-0.05200**
-0.05145**
-0.05612**
0.00306895
-0.00712*
-0.00669*
-0.01802**
272,080
571,648
552,888
273,524
Test Period
Measure
(Two Weeks
Only
11/20/05 to
12/4/05)
Mean (mph)
Percent in 10
mph pace
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
Decrease/Increase Decrease/Increase
Compared to
Compared To
Two Years
One Year
Earlier
Earlier
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.3 (b): ATR-175—Additional Speed Data from Regular Enforcement
Period #1
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Two Weeks
Only
11/20/05 to
12/4/05)
7.10936*
71.10897295
63.63578941
76.16976591
77.7141657
79.25856549
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-81
Table 5.4 (a): ATR-175—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70
mph) During Regular Enforcement Period #1 and During the Previous Three Years
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Test
Period
(Two
Weeks
Only
11/20/05 to
12/4/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
51,116
3,651
-3,681
-3,416
-1,563
7,073
505
-1,010
-1000
-1,091
272,080
19,434
—
—
—
Table 5.4 (b): ATR-175—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70 mph) During
Regular Enforcement Period #1 and During the Previous Three Years
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
-0.18942
-0.1758
-0.08041
0.025996
0.187871
505
0.025996
-0.05200
-0.05145
-0.05612
272,080
19,434
—
—
—
Test Period
(Two
Weeks
Only
11/20/05 to
12/4/05)
0.187871
Daily
Average
in Test
Period
A2-82
ATR-191: Enhanced Enforcement Period #1
Table 5.5 (a): ATR-191—Comparison of Speed Data from Enhanced Enforcement
Period #1 with Speed Data from the Three Previous Years
Decrease/Increase Decrease/Increase
Compared to
Compared to
Three Years
Two Years
Earlier
Earlier
Measure
Test Period
(9/26/05 to
11/6/05)
Decrease/Increase
Compared to
One Year Earlier
Mean (mph)
72.33672
-0.31314**
+0.635439**
+0.272681**
Percent in 10
mph pace
61.7101
+10.1369**
16.7594**
+11.839**
0.936157
+0.064302**
0.136445**
+0.095045**
0.690202
+0.017833*
0.092891**
+0.050786**
0.320454
-0.09116**
-0.02478*
-0.03039*
0.071508
-0.03592**
-0.08593**
-0.05718**
0.008433
-0.00829*
-0.0274**
-0.01205**
2,183,456
1,905,909
1,943,586
1,863,269
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.5 (b): ATR-191—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard
deviation (mph)
Median (mph)
15th percentile
(mph)
85th percentile
(mph)
th
90 percentile
(mph)
95th percentile
(mph)
Test Period
(9/26/05 to
11/6/05)
6.50857*
72.57205
66.75148
78.42352
79.42775
81.70498
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-83
Table 5.6 (a): ATR-191—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70
mph) During Enhanced Enforcement Period #1 and During the Previous Three
Years
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
699,697
16,659
-4,739
-1,288
-1,580
156,135
3,717
-1,867
-4,467
-2,973
2,183,456
51,987
—
—
—
Table 5.6 (b): ATR-191—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70 mph) During
Enhanced Enforcement Period #1 and During the Previous Three Years
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Decrease/
Increase
Compared
to One Year
Earlier
Test Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
0.320454
0.320454
0.071508
0.071508
-0.09116
-1,867
-0.03592
2,183,456
51,987
—
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
-0.02478
-0.03039
-0.08593
-0.05718
—
—
ATR-191—Regular Enforcement Period #1
Throughout the First Regular Enforcement Period #1, there were problems with the speed
data collected at ATR-191. Because these data were unreliable, we were unable to make
meaningful comparisons with the historical speed data.
ATR-208: Enhanced Enforcement Period #1 and Regular Enforcement Period #1
There were also problems with the speed data collected at ATR-208. But in this case, the
data were unreliable throughout both the First Enhanced and the First Regular
Enforcement Periods. Because the data were unreliable, we were could not make
meaningful comparisons with the historical speed data for either period.
A2-84
ATR-227: Enhanced Enforcement Period #1
Table 5.7: ATR-227—Comparison of Speed Data from Enhanced Enforcement
Period #1 with Speed Data from the Previous Two Years
Decrease/Increase
Compared to
Two Years Earlier
(All Six Weeks)
Measure
(Two Weeks Only
10/24/05 to 11/6/05)
Decrease/Increase
Compared to
One Year Earlier
(All Six Weeks)
Mean (mph)
71.34990379
-0.31075**
+1.613121**
Percent in 10 mph
pace
61.7587962
+3.0352*
+4.7813*
0.863595833
ns
+0.051212**
0.666103498
-0.012*
+0.10678**
0.253050497
-0.04791*
+0.021796*
0.029472499
-0.01214*
-0.00918*
0.0048104
-0.00238*
-0.00237*
127,848
403,340
426,578
Test Period
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.7 (b): ATR-227—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Two Weeks Only
10/24/05 to 11/6/05)
6.03162*
72.0106802
65.34421165
77.30457599
78.42275399
79.54093199
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-85
Table 5.8 (a): ATR-227—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70
mph) During Enhanced Enforcement Period #1 and During the Previous Two Years
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Test
Period
(Two
Weeks
Only
10/24/05 to
11/6/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
32,352
2,311
-438
+199
3,768
269
-111
-88
127,848
9,132
—
—
Table 5.8 (b): ATR-227—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70 mph) During
Enhanced Enforcement Period #1 and During the Previous Two Years
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
0.253051
0.253051
0.04791
+0.021796
0.029472
0.029472
-0.01214
-0.00918
127,848
9,132
—
—
Test Period
(Two
Weeks
Only
10/24/05 to
11/6/05)
A2-86
ATR-227—Regular Enforcement Period #1
Table 5.9 (a): ATR-227—Comparison of Speed Data from Regular Enforcement
Period #1 with Speed Data from the Previous Two Years
Measure
Test Period
(Two Weeks Only
11/7/05 to
11/20/05)
Decrease/Increase
Compared to
One Year Earlier
(All Four Weeks)
Decrease/Increase
Compared to
Two Years Earlier
(All Four Weeks)
Mean (mph)
69.21660551
-2.70958**
-2.59142**
Percent in 10 mph
pace
52.3007103
-9.602**
-9.998**
0.754205543
-0.13488**
-0.13726**
0.553209182
-0.15541**
-0.14076**
0.199798592
-0.10249**
-0.08598**
0.024474164
-0.01367*
-0.01596*
0.004028167
-0.00243*
-0.00246*
131,077
263,370
253,865
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.9 (b): ATR-227—Additional Speed Data from Regular Enforcement
Period #1
Measure
Standard deviation
(mph)
Median (mph)
15th percentile
(mph)
th
85 percentile
(mph)
90th percentile
(mph)
th
95 percentile
(mph)
Test Period
(Two Weeks Only
11/7/05 to 11/20/05)
8.05186*
70.75279553
61.86949638
76.42018407
77.84611201
79.27203995
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-87
Table 5.10 (a): ATR-227—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70
mph) During Regular Enforcement Period #1 and During the Previous Two Years
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Test
Period
(Two
Weeks
Only
11/7/05 to
11/20/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
26,189
1,871
-960
-805
3,208
229
-128
-149
131,077
9,363
—
—
Table 5.8 (b): ATR-227—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70 mph) During
Regular Enforcement Period #1 and During the Previous Two Years
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Test Period
(Two
Weeks
Only
11/7/05 to
11/20/05)
Daily
Average
in Test
Period
0.199799
0.199799
0.024474
131,077
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
-0.08598
0.024474
-0.10249
-128
-0.01367
9,363
—
—
-0.01596
5.2. Speed Data from One ATR located Outside Enhanced Enforcement Zones
There was one ATR located on a Rural Freeway Outside the Enhanced Enforcement
Zones. It was ATR-200, on I-94, near Hasty in Wright County. During the MSMP, at
this ATR location the speed limit remained unchanged at 70 mph and there was no
change in enforcement. No historical speed data were available for either the First
Enhanced or the First Regular Enhancement Periods for ATR-200. However, we were
able to use Pre-MSMP speed data that came from a four-week period from 4/24/05 to
5/21/05. These data are compared with speed data from the First Enhanced Enforcement
Period, and the First Regular Enhancement Period.
Two tables are presented for each time period. In the first table, speed data from the Test
Year is compared with the historical speed data. In the second of the two tables, the
focus is on drivers who were traveling at least 5 mph and at least 10 mph above the speed
A2-88
limit—i.e., drivers traveling at 75 mph or more and at 80 mph or more. We also present
the average number of vehicles traveling above these speeds every day. Then, the table
presents the decrease in the number of vehicles relative to the number that were traveling
at these speeds before the MSMP was implemented.
ATR-200—Enhanced Enforcement Period #1
Table 5.11: ATR-200—Speed Data from Enhanced Enforcement Period #1
Compared with Pre-MSMP Speed Data from 4/24/05 to 5/21/05
Measure
Test Period
(9/26/05 to 11/6/05)
Decrease/Increase
Compared to Pre-Test
Period
(4/24/05 to 5/21/05)
Mean (mph)
72.11540413
-1.19500**
Percent in 10 mph pace
59.9613152
+7.2668**
0.892373342
+0.009011*
0.706035356
+0.001239
0.33923331
-0.070113**
0.04305078
-0.107785**
0.005034712
-0.045952**
1,714,696
1,206,904
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.11 (b): ATR-200—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(9/26/05 to 11/6/05)
6.61122*
72.80853608
66.13700225
78.19453868
79.03861278
79.88268687
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-89
Table 5.12 (a): ATR-200—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70
mph) During Enhanced Enforcement Period #1 and During the Pre-MSMP Speed
Data from 4/24/05 to 5/21/05
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Test Period
(9/26/05 to
10/09/05)
Daily
Average in
Test Period
Decrease/
Increase
Compared to PreTest Period
(4/24/05 to 5/21/05)
581,682
13,850
-2,862
73,819
1,758
-4,400
1,714,696
40,826
—
Table 5.12 (b): ATR-200—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70 mph) During
Enhanced Enforcement Period #1 and During the Pre-MSMP Speed Data from
4/24/05 to 5/21/05
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Test Period
(9/26/05 to
10/09/05)
Daily
Average in
Test Period
Decrease/
Increase
Compared to PreTest Period
(4/24/05 to 5/21/05)
0.339233
0.339233
-0.070113
0.043051
0.043051
-0.107785
1,714,696
40,826
—
A2-90
ATR-200—Regular Enforcement Period #1
Table 5.13 (a): ATR-200—Speed Data from Regular Enforcement Period #1
Compared with Pre-MSMP Speed Data from 4/24/05 to 5/21/05
Measure
Test Period
(11/7/05 to 12/4/05)
Decrease/Increase
Compared to
Pre-Test Period
(4/24/05 to 5/21/05)
Mean (mph)
71.85011991
-1.46028**
Percent in 10 mph pace
58.6154408
+5.9209**
0.879795852
-0.00357*
0.691942122
-0.01285*
0.328306104
-0.08104**
0.046770175
-0.10407**
0.007010576
-0.04398**
1,206,904
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
1,050,413
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.13 (b): ATR-200—Additional Speed Data from Regular Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(11/7/05 to 12/4/05)
7.02619*
72.63920669
65.79305989
78.16666695
79.05465308
79.94263921
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-91
Table 5.14 (a): ATR-200—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70
mph) During Regular Enforcement Period #1 and During the Pre-MSMP Speed
Data from 4/24/05 to 5/21/05
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Test Period
(11/7/05 to
12/4/05)
Daily
Average in
Test Period
Decrease/
Increase
Compared to PreTest Period
(4/24/05 to 5/21/05)
344,857
12,316
-3,040
49,128
1,755
-3,904
1,050,413
37,515
—
Table 5.14 (b): ATR-200—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70 mph) During
Regular Enforcement Period #1 and During the Pre-MSMP Speed Data from
4/24/05 to 5/21/05
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Test Period
(11/7/05 to
12/4/05)
Daily
Average in
Test Period
Decrease/
Increase
Compared to PreTest Period
(4/24/05 to 5/21/05)
0.328306
0.328306
-0.08104
0.046770
0.046770
-0.10407
1,050,413
37,515
—
5.3. Overall Effect of the MSMP on Rural Freeways
In the MSMP, we obtained speed data from five ATRs located on Rural Freeways—four
of these ATRs were located Within Enhanced Enforcement Zones, while the remaining
ATR was located Outside the Enhanced Enforcement Zones. At the locations of all five
ATRs the speed limit remained unchanged at 70 mph.
In order to provide a brief overall summary of the effect of the MSMP, speed data from
the ATRs Within Enhanced Enforcement Zones were combined. We combined the
speed data from ATR-175, ATR-191, and ATR-227—the data for ATR-208 were not
reliable for this period. We compared the combined speed data from the Test Period with
the historical speed data from the previous year. For this summary, we focused on
drivers traveling at least 10 mph above the speed limit—i.e., those traveling at 80 mph or
A2-92
more. Table 5.15 shows the results of this comparison for the First Enhanced
Enforcement Period.
Table 5.15: Effect of MSMP on Rural Freeways during the First Enhanced
Enforcement Period at Three ATRs (ATR-175, ATR-191, and ATR-227) Within
Enhanced Enforcement Zones
Sample Total
3,234,647
Sample Total
3,144,439*
One Year Before MSMP
# Over 80 mph
299,211
First Enhanced Enforcement Period
# Over 80 mph
252,726*
% Over 80 mph
9.25
% Over 80 mph
8.04*
Result: 13.08% Reduction in Drivers over 80 mph
*Numbers adjusted to account for limited availability of data from ATR-175 and ATR-227 during the time
period
Table 5.17 indicates that, for three of the four ATRs Within Enhanced Enforcement
Zones on Rural Freeways, during the First Enhanced Enforcement Period, there was a
13.08% decrease in the number of drivers traveling at over 80 mph—i.e., 10 mph over
the speed limit—as compared to the month before the MSMP was implemented.
A similar comparison was conducted for the First Regular Enforcement Period.
However, in this case we were only able to use speed data from two ATRs (ATR-175 and
ATR-227)—this speed data for ATR-191 and ATR-208 were not reliable for this time
period. The results of this comparison using speed data from the three ATRs are shown
in Table 5.16.
Table 5.16: Effect of MSMP on Rural Freeways During the First Regular
Enforcement Period at Two ATRs (ATR-175 and ATR-227) Within Enhanced
Enforcement Zones
Sample Total
835,018
Sample Total
806,314*
One Year Before MSMP
# Over 80 mph
54,635
First Regular Enforcement Period
# Over 80 mph
20,562*
% Over 80 mph
6.54
% Over 80 mph
2.55*
Result: 38.99% Reduction in Drivers over 80 mph
*Numbers adjusted to account for limited availability of data from ATR-175, and ATR-227 during the time
period
Table 5.18 indicates that, for three of the four ATRs located Within Enhanced
Enforcement Zones on Rural Freeways, during the First Regular Enforcement Period,
A2-93
there was a 38.99% decrease in the number of drivers traveling over 80 mph—i.e., 10
mph over the speed limit.
We also examined the difference between the speed data obtained during the Test Periods
from the ATR that was located Outside the Enhanced Enforcement Zones. We focused
on drivers traveling at 80 mph or more—10 mph above the speed limit. The results of
this comparison for speed data obtained during the First Enhanced Enforcement Period
are shown in Table 5.19.
Table 5.17: Effect of the MSMP on One ATR Outside the Enhanced Enforcement
Zones on a Rural Freeway During First Enhanced Enforcement Period
Pre-MSMP Speed Data from 4/24/05 to 5/21/05
# Over 80 mph
% Over 80 mph
182,044
15.08
First Enhanced Enforcement Period
Sample Total
# Over 80 mph
% Over 80 mph
1,714,696
73,819
4.31
Sample Total
1,206,904
Result: 71.42% Decrease in Drivers Traveling over 80 mph
Table 5.19 shows that, for the ATR located Outside Enhanced Enforcement Zones on a
Rural Freeway, during the First Enhanced Enforcement Period, there was a 71.42%
decrease in the number of drivers traveling over 80 mph.
A similar comparison was conducted for the First Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 5.20.
Table 5.18: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on a Rural Freeway During First Regular Enforcement Period
Pre-MSMP Speed Data from 4/24/05 to 5/21/05
# Over 80 mph
% Over 80 mph
182,044
15.08
First Regular Enforcement Period
Sample Total
# Over 80 mph
% Over 80 mph
1,050,413
49,128
4.68
Sample Total
1,206,904
Result: 68.97% Decrease in Drivers Traveling over 80 mph
Table 5.18 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
a Rural Freeway, during the First Regular Enforcement Period there was a 68.97%
decrease in the number of drivers traveling over 80 mph.
A2-94
For Rural Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
Zones should be treated with caution. It should be noted that while the location of ATR200 is Outside the Enhanced Enforcement Zones, nevertheless it is between Enhanced
Enforcement Zones to both the North-West and the South-East. And it is likely that most
drivers passing ATR-200 will have traveled through one or other of the Enhanced
Enforcement Zones. [It should also be noted that there are no other ATRs Outside the
Enhanced Enforcement Zones on Rural Freeways that could have been considered for
comparison purposes for this study.] Also, the speed data used in the comparisons for the
ATR located Outside the Enhanced Enforcement Zones was from a different time period
(4/24/05 to 5/21/05) from the time periods for the First Enhanced Enforcement Period
(9/26 to 11/6) and the First Regular Enforcement Period (11/7 to 12/4).
A2-95
Section 6. Speed Data Obtained on Urban Freeways
We obtained speed data from four ATRs located on Urban Freeways. Three of these
ATRs were located Within Enhanced Enforcement Zones, while the remaining ATR was
located Outside the Enhanced Enforcement Zones. During the MSMP, at the locations of
the three ATRs Within the Enhanced Enforcement Zones, the speed limit was increased
from 55 mph to 60 mph and there was Enhanced Enforcement at various times. In
contrast, at the location of the ATR Outside the Enhanced Enforcement, the speed limit
remained unchanged at 55 mph and there was no change in the level of enforcement
during the MSMP.
In this section of the report, for the ATRs located Within Enhanced Enforcement Zones
and the single ATR located Outside the Enhanced Enforcement Zones, we present
comparisons of the speed data obtained during the Test Year with speed data obtained at
those same ATRs before the MSMP was implemented.
It should be noted that, for the three ATRs Within Enhanced Enforcement Zones, there is
only very limited historical speed data. There is only speed data collected in the weeks
just before the MSMP began—specifically, the data is from September 2005 (with, in
two cases, data from the last two days in August, 2005). The available data is not the
same for all three ATRs—the actual time periods for which data were available are noted
in the comparison tables below. The result of comparing this August/September data with
the data collected at various times throughout the year should be considered with some
caution, as there may be seasonal effects that confound the effects of the MSMP.
There is historical speed data for the ATR located Outside the Enhanced Enforcement
Zones.
Comparisons using the speed data from the ATRs located Within Enhanced Enforcement
Zones are presented first. Then, we present comparisons using the speed data from the
ATR located Outside the Enhanced Enforcement Zones.
In making the comparisons between the speed data obtained during the Test Year and the
speed data obtained prior to the MSMP, we used two statistical tests. The first test was
used to examine differences in the mean speeds—for this we used the procedure for
comparing population means outlined by Kitchens (1987, p 369-373). The second test
was used to explore differences in the percentage of vehicles in the 10 mph pace and in
the differences in the proportions of vehicle traveling at various speeds. For this test, we
treated the distribution of speeds as a Bernoulli population—i.e., a population in which
each element is one of two possibilities, in this case, (1) in or out of the 10 mph pace, or
(2) above or below a selected speed (e.g., 75 mph). We then used the procedure for
comparing population proportions described by Kitchens (1987, pages 400-404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
A2-96
ATR in the time periods under consideration. Second, the tests were conducted using an
extremely conservative correction, with n-values equal to the number of hours in each
test period—the rationale for this was that it is possible, when traffic is congested, that
individual vehicles may travel at speeds which are not independent of each other.
6.1. Speed Data from ATRs located Within Enhanced Enforcement Zones
The three ATRs located Within Enhanced Enforcement Zones on Urban Freeways were
as follows: (1) ATR 100, on Highway 100 near Brooklyn Center in Hennepin County, (2)
ATR I94, on I-94 South of the 57th Street Bridge in Hennepin County, and (3) ATR35WCD, on I-35W, near Roseville in Ramsey County. At the locations of all three of
these ATRs, the speed limit was increased from 55 mph to 60 mph during the MSMP.
The effect of the MSMP on the speed data at each of these three ATRs is reported in this
section. It is reported ATR by ATR—with the effect of the MSMP in the First Enhanced
Enforcement Period followed by its effect in the First Regular Enhancement Period.
For each of the three ATRs Within Enhanced Enforcement Zones, two tables are
presented for each time period. In the first of these tables speed data from the Test Year
is compared with pre-MSMP speed data, which for these ATRs is limited to speed data
from September 2005 (and, in two cases, from the last two days in August, 2005)—the
specific dates from which data are available are noted in the table. In the second of the
two tables for each ATR, the focus is on drivers traveling at least 5 mph and at least 10
mph above the new speed limit adopted for the MSMP—i.e., on drivers traveling at 65
mph or more and at 70 mph or more. In this second table, we present the number (and
proportion) of vehicles traveling above these speeds throughout the six-week Enhanced
Enforcement Period or the four-week Regular Enhancement Period. We also present the
average number of vehicles traveling above these speeds every day. Then, the table
presents the decrease in the number of vehicles relative to the number that were traveling
at these speeds before the MSMP. It should be noted that before the MSMP was adopted,
these speeds (of 65 mph or more and 70 mph or more) were 10 mph and 15 mph above
the pre-MSMP speed limit.
A2-97
ATR-100—Enhanced Enforcement Period #1
Table 6.1 (a): ATR-100—Comparison of Speed Data from Enhanced Enforcement
Period #1 with Speed Data from Two Weeks in September 2005
Measure
Test Period
(9/26/05 to 11/6/05)
Decrease/Increase
Compared to PreTest Period
(9/12/05 to 9/25/05)
Mean (mph)
58.41635745
-2.15422**
Percent in 10 mph pace
49.6221149
-7.903**
0.230516858
-0.05273*
0.068221109
-0.02396*
0.01779154
-0.00743*
0.004818595
-0.00166*
0.001296215
-0.00046*
3,150,711
1,089,474
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.1 (b): ATR-100—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(9/26/05 to 11/6/05)
11.81423*
60.5411715
51.84204546
67.48055968
69.02095739
71.80658982
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-98
Table 6.2 (a): ATR-100—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #1 with Speed Data from Two Weeks
in September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(9/26/05 to
10/09/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to PreTest Period
(9/12/05 to 9/25/05)
726,292
17,292
-3,956
214,945
5,118
+1,797
3,150,711
75,017
—
Table 6.2 (b): ATR-100—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #1 with Speed Data from Two Weeks in September
2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(9/26/05 to
10/09/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to PreTest Period
(9/12/05 to 9/25/05)
0.230517
0.230517
-0.05273
0.068221
0.068221
-0.02396
3,150,711
75,017
—
A2-99
ATR-100—Regular Enforcement Period #1
Table 6.3 (a): ATR-100—Comparison of Speed Data from Regular Enforcement
Period #1 with Speed Data from Two Weeks in September 2005
Measure
Test Period
(11/07/05 to
12/04/05)
Decrease/Increase
Compared to PreTest Period
(9/12/05 to 9/25/05)
Mean (mph)
58.67789
-1.89269**
Percent in 10 mph pace
54.4326
-3.093*
0.211709
-0.07154**
0.06684
-0.02534*
0.014079
-0.01115*
0.003806
-0.00267*
0.001127
-0.00062*
2,069,854
1,089,474
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.3 (b): ATR-100—Additional Speed Data from Regular Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(11/07/05 to 12/04/05)
10.75816
60.01083
52.84512
67.12981
68.85551
71.59588
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-100
Table 6.4 (a): ATR-100—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #1 with Speed Data from Two Weeks in
September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to PreTest Period
(9/12/05 to 9/25/05)
438,207
15,650
-5,288
138,349
4,941
-1,873
2,069,854
73,923
—
Table 6.4 (b): ATR-100—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #1 with Speed Data from Two Weeks in September
2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to PreTest Period
(9/12/05 to 9/25/05)
0.211709
0.211709
-0.07154
0.06684
0.06684
-0.02534
2,069,854
73,923
—
A2-101
ATR-I94—Enhanced Enforcement Period #1
Table 6.5 (a): ATR-I94—Comparison of Speed Data from Enhanced Enforcement
Period #1 with Speed Data from Four Weeks in August and September 2005
Measure
Test Period
(9/26/05 to 11/6/05)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
63.22481262
-0.32004**
Percent in 10 mph pace
55.0771104
-0.58091*
0.39266992
-0.02013*
0.159703611
+0.002782*
0.062160417
+0.003183*
0.024366368
+0.004125*
0.01084978
+0.002281*
5,275,222
3,409,707
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.5 (b): ATR-I94—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(9/26/05 to 11/6/05)
9.60637*
63.38306085
56.7551384
70.4974007
73.06036785
76.60877405
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-102
Table 6.6 (a): ATR-I94—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #1 with Speed Data from Four Weeks
in August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(9/26/05 to
10/09/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
2,071,421
49,320
-2,529
842,474
20,059
+349
5,275,222
125,601
—
Table 6.6 (b): ATR-I94—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #1 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(9/26/05 to
10/09/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
0.392670
0.392670
-0.020133
0.159704
0.159704
+0.002782
5,275,222
125,601
—
A2-103
ATR-I94—Regular Enforcement Period #1
Table 6.7 (a): ATR-I94—Comparison of Speed Data from Regular Enforcement
Period #1 with Speed Data from Four Weeks in August and September 2005
Measure
Test Period
(11/07/05 to
12/04/05)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
60.55887578
-2.98597**
Percent in 10 mph pace
51.4648489
-0.04193*
0.314037753
-0.09876**
0.134618562
-0.0223*
0.043282371
-0.01569*
0.015705707
-0.00454*
0.006958302
-0.00161*
3,286,003
3,409,707
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.7 (b): ATR-I94—Additional Speed Data from Regular Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(11/07/05 to
12/04/05)
11.62103*
61.841699
53.9690699
69.57135473
71.89511747
74.63225808
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-104
Table 6.8 (a): ATR-I94—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #1 with Speed Data from Four Weeks in
August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
1,031,929
36,855
-11,590
442,357
15,798
-2,617
3,286,003
117,357
—
Table 6.8 (b): ATR-I94—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #1 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
0.314038
0.314038
-0.09876
0.134619
0.134619
-0.0223
3,286,003
117,357
—
A2-105
ATR-35WCD—Enhanced Enforcement Period #1
Table 6.9 (a): ATR-35WCD—Comparison of Speed Data from Enhanced
Enforcement Period #1 with Speed Data from Four Weeks in August and
September 2005
Measure
Test Period
(9/26/05 to 11/6/05)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
59.70418854
-0.303588**
Percent in 10 mph pace
49.9251118
+1.6377*
0.318674006
-0.03317*
0.096391484
-0.02106*
0.019565253
-0.00677*
0.003779392
-0.00141*
0.00088397
-0.0003*
4,562,374
3,030,663
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.9 (b): ATR-35WCD—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(9/26/05 to 11/6/05)
12.30691*
62.23020814
53.68348965
68.7941356
69.91883041
73.01924767
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-106
Table 6.10 (a): ATR-35WCD—Comparison of the Daily Average Number of
Vehicles Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit
(of 60 mph) During Enhanced Enforcement Period #1 with Speed Data from Four
Weeks in August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(9/26/05 to
11/6/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
1,453,910
34,617
-3,603
439,774
10,471
-2,288
4,562,374
108,628
—
Table 6.10 (b): ATR-35WCD—Comparison of the Proportion of Vehicles Traveling
at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #1 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(9/26/05 to
11/6/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
0.318674
0.318674
-0.03317
0.096391
0.096391
-0.02106
4,562,374
108,628
—
A2-107
ATR-35WCD—Regular Enforcement Period #1
Table 6.11 (a): ATR-35WCD —Comparison of Speed Data from Regular
Enforcement Period #1 with Speed Data from Four Weeks in August and
September 2005
Measure
Test Period
(11/07/05 to
12/04/05)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
59.97221123
-0.03557**
Percent in 10 mph pace
48.6986707
+0.4113*
0.325351786
-0.0265*
0.103883006
-0.01357*
0.023099794
-0.00323*
0.006212546
+0.001019*
0.002185645
+0.000997*
2,883,359
3,030,663
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.11 (b): ATR-210—Additional Speed Data from Regular Enforcement
Period #1
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(11/07/05 to 12/04/05)
11.71003*
62.11671341
52.77143848
68.95883758
70.24033495
73.33503737
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-108
Table 6.12 (a): ATR-35WCD—Comparison of the Daily Average Number of
Vehicles Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit
(of 60 mph) During Regular Enforcement Period #1 with Speed Data from Four
Weeks in August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
938,106
33,504
-2,729
299,532
10,698
-1,397
2,883,359
102,977
—
Table 6.12 (b): ATR-35WCD—Comparison of the Proportion of Vehicles Traveling
at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #1 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(11/07/05 to
12/04/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
0.325352
0.325352
-0.0265
0.10388
0.10388
-0.01357
2,883,359
102,977
—
6.2. Speed Data from One ATR located Outside Enhanced Enforcement Zones
There was one ATR that was located on an Urban Freeway Outside the Enhanced
Enforcement Zones. It was ATR-335, on I-35W at County Road 53 in Anoka County.
During the MSMP, at this ATR location the speed limit remained unchanged at 55 mph
and there were no changes in enforcement. For ATR-335, the speed data obtained during
2005, when the MSMP occurred, was compared with historical speed data. Comparisons
are presented for the first six-week time period between 9/26 and 11/6, when the First
Enhanced Enforcement Period occurred during the MSMP, and then for the four-week
time period between 11/7 and 12/4, when the First Regular Enhancement Period
occurred.
Two tables are presented for each of these time periods. In the first table speed data from
the Test Year is compared with the historical speed data. We include speed data from the
three years prior to the MSMP in this table. In the second of the two tables, the focus is
A2-109
on drivers who were traveling at least 5 mph and at least 10 mph above the new speed
limit adopted for the MSMP—i.e., drivers traveling at 65 mph or more and at 70 mph or
more. It should be noted that during the MSMP, as well as during the three years before
it was adopted, these speeds (65 mph or more and 70 mph or more) were 10 mph and 15
mph above the actual speed limit at the location of ATR-335. In this second table, we
present the number (and proportion) of vehicles traveling above these speeds throughout
the six-week Enhanced Enforcement Period or the four-week Regular Enhancement
Period. We also present the average number of vehicles traveling above these speeds
every day. Then, the table presents the decrease in the number of vehicles relative to the
number that were traveling at these speeds before the MSMP was implemented.
A2-110
ATR-335—Enhanced Enforcement Period #1
Table 6.13: ATR-335—Speed Data from Enhanced Enforcement Period #1
Compared with Speed Data from Three Previous Years
Decrease/
Increase as
Compared to
Three Years
Earlier
Measure
Test Period
(9/26/05 to
11/6/05)
Decrease/Increase
as Compared to
One Year Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Mean (mph)
69.70688
-0.93964**
-0.10441**
-4.16968**
Percent in 10 mph
pace
63.4758
+5.1241**
+5.7268**
+3.9628*
0.831646
ns (-0.00074643)
+0.043488**
-0.10550**
0.54388
-0.03685*
+0.037884*
-0.21600**
0.182446
-0.05509**
-0.02265*
-0.2468**
0.045395
-0.02815**
-0.00088*
-0.09408**
0.009482
-0.00648*
-0.00061*
-0.01491**
1,868,362
1,940,361
1,925,901
1,582,511
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.13 (b): ATR-335—Additional Speed Data from Enhanced Enforcement
Period #1
Measure
Standard deviation
(mph)
Median (mph)
15th percentile
(mph)
85th percentile
(mph)
th
90 percentile
(mph)
95th percentile
(mph)
Test Period
(9/26/05 to
11/6/05)
8.71386*
70.60703
64.20254
76.18372
78.00785
79.83199
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-111
Table 6.14 (a): ATR-335—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #1 and During the Previous Three
Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
1,553,815
36,996
-33
+1,934
-4,693
1,016,165
24,195
-1,639
+1,685
-9,609
1,868,362
44,485
—
—
—
Table 6.14 (b): ATR-335—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #1 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(9/26/05 to
10/09/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.831646
0.831646
-0.000746
+0.043488
-0.10550
0.54388
0.54388
-0.03685
+0.037884
-0.21600
1,868,362
44,485
—
—
—
A2-112
ATR-335—Regular Enforcement Period #1
Table 6.15 (a): ATR-335—Speed Data from Regular Enforcement Period #1
Compared with Speed Data from Three Previous Years
Measure
Test Period
(11/07/05 to
12/04/05)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
69.04164
-1.63323**
-0.40954**
-5.09678**
Percent in 10 mph
pace
58.314
+0.017571*
+0.022249*
-0.04447*
0.78188
-0.03737*
NS (-0.000507)
-0.16907**
0.490051
-0.08017**
-0.00889*
-0.29674**
0.162676
-0.08001**
-0.04089*
-0.27752**
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.042313
-0.03277**
-0.01076*
-0.09253**
0.009405
-0.00712*
ns
-0.01281
Vehicle Total
1,115,042
1,175,639
1,143,282
999,999
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.15 (b): ATR-335—Additional Speed Data from Regular Enforcement
Period #1
Measure
Standard deviation
(mph)
Median (mph)
15th percentile
(mph)
85th percentile
(mph)
th
90 percentile
(mph)
95th percentile
(mph)
Test Period
(11/07/05 to
12/04/05)
8.386351
69.82955
62.5536
75.52659
77.60364
79.68068
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A2-113
Table 6.16 (a): ATR-335—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #1 and During the Previous Three Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
11/07/05 to
12/04/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
871,829
31,137
-1,448
-20
-6,733
546,428
19,515
-3,193
-354
-11,817
1,115,042
39,823
—
—
—
Table 6.16 (b): ATR-335—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #1 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
11/07/05 to
12/04/05)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.78188
0.78188
-0.03737
-0.000507
-0.16907
0.490051
0.490051
-0.08017
-0.00889
-0.29674
1,115,042
39,823
—
—
—
6.3. Overall Effect of the MSMP on Urban Freeways
In the MSMP, we obtained speed data from four ATRs located on Urban Freeways—
three of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining ATR was located Outside the Enhanced Enforcement Zones. The speed limit
was increased from 55 mph to 60 mph at the locations of the three ATRs Within
Enhanced Enforcement Zones, while the speed limit remained unchanged at 55 mph at
location of the ATR Outside the Enhanced Enforcement Zones
In order to provide a brief overall summary of the effect of the MSMP, speed data from
the three ATRs Within Enhanced Enforcement Zones were combined. For this summary,
we focused on drivers traveling at least 10 mph above the new speed limit. Then, we
compared speed data collected during the First Enhanced Enforcement Period with preMSMP speed data that were collected just before the Enhanced Enforcement began—this
data was collected two weeks during September 2005 for ATR-100, and four weeks
A2-114
during August and September 2005 for ATR-I94 and ATR-35WCD. When the preMSMP data were collected the speed limit at the locations of the three ATRs was still 55
mph. Table 6.17 shows the results of this comparison for the First Enhanced
Enforcement Period.
Table 6.17: Effect of MSMP on Urban Freeways during the First Enhanced
Enforcement Period at Three ATRs Within Enhanced Enforcement Zones
Sample Total
8,619,318*
Sample Total
12,988,307
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879**
First Enhanced Enforcement Period
# Over 70 mph
1,497,191
% Over 70 mph
12.67**
% Over 70 mph
11.53
Result: 9.00% Reduction in Drivers over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-100 during the pre-MSMP time
period
Table 6.17 indicates that, for the three ATRs Within Enhanced Enforcement Zones on
Urban Freeways, during the First Enhanced Enforcement Period, there was a 9.00%
decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the new
speed limit—as compared to the month before the MSMP was implemented.
A similar comparison was conducted for the First Regular Enforcement Period. The
results of this comparison using speed data from the three ATRs are shown in Table 6.18.
Table 6.18: Effect of MSMP on Urban Freeways during the First Regular
Enforcement Period at Three ATRs Within Enhanced Enforcement Zones
Sample Total
8,619,318*
Sample Total
8,239,216
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879**
First Regular Enforcement Period
# Over 70 mph
880,238
% Over 70 mph
12.67**
% Over 70 mph
10.68
Result: 15.71% Reduction in Drivers over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-100 during the pre-MSMP time
period
Table 6.18 indicates that, for the three ATRs located Within Enhanced Enforcement
Zones on Urban Freeways, during the First Regular Enforcement Period, there was a
10.71% decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the
new speed limit—as compared to the month before the MSMP was implemented.
A2-115
We also examined the difference between the speed data obtained during the Test Periods
from the ATR that was located Outside the Enhanced Enforcement Zones. For this ATR
location there was no change in the level of enforcement during the MSMP and no
change in the speed limit. For comparison purposes, we focused on drivers traveling at
70 mph or more—while this is 10 mph above the new speed limit Within Enhanced
Enforcement Zones, it is 15 mph above the actual speed limit at the location of the ATR
Outside Enhanced Enforcement Zones. The results of this comparison for speed data
obtained during the First Enhanced Enforcement Period are shown in Table 6.19.
Table 6.19: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on an Urban Freeway during First Enhanced Enforcement Period
Sample Total
1,940,361
Sample Total
1,868,362
One Year Before MSMP
# Over 70 mph
1,126,829
First Enhanced Enforcement Period
# Over70 mph
1,016,165
% Over 70 mph
58.07
% Over 70 mph
54.39
Result: 6.34% Decrease in Drivers Traveling over 70 mph
Table 6.19 shows that, for the ATR located Outside Enhanced Enforcement Zones on an
Urban freeway, during the First Enhanced Enforcement Period, there was a 6.34%
decrease in the number of drivers traveling over 70 mph—i.e., 10 mph above the new
speed limit Within Enhanced Enforcement Zones (and 15 mph above the current speed
limit Outside the Enhanced Enforcement Zones).
A similar comparison was conducted for the First Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 6.20.
Table 6.20: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on an Urban Freeway during First Regular Enforcement Period
Sample Total
1,175,639
Sample Total
1,115,042
One Year Before MSMP
# Over 70 mph
670,378
First Regular Enforcement Period
# Over 70 mph
546,428
% Over 70 mph
57.02
% Over 70 mph
49.01
Result: 14.05% Decrease in Drivers Traveling over 70 mph
Table 6.20 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
an Urban Freeway, during the First Regular Enforcement Period there was a 14.05%
A2-116
decrease in the number of drivers traveling over 70 mph—i.e., at 10 mph or more above
the new speed limit Within Enhanced Enforcement Zones (and 15 mph or more above the
current speed limit Outside Enhanced Enforcement Zones).
For Urban Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
Zones should be treated with caution. It should be noted that the location of ATR that
was located Outside the Enhanced Enforcement Zones is only a few miles to the North of
an Enforced Enforcement Zone. And, most of the drivers traveling North past this ATR
will have traveled through that Enhanced Enforcement Zone. [It should also be noted
that, the locations of all the other ATRs Outside the Enhanced Enforcement Zones on
Urban Freeways that might have been considered for comparison purposes for this study
are also very close to Enhanced Enforcement Zones.]
A2-117
Section 7. Crash Data
During the First MSMP Test Period, crash data were available for all Minnesota trunk
highways. These trunk highways included 2-Lane/2-Way Highways, 4-Lane Highways,
Rural Freeways, and Urban Highways. Some of these highways had changes in speed
limits during the MSMP, some had enhanced enforcement during the MSMP, and speed
data were available from some of them. In all, there were twelve combinations of Road
Type, Speed Limits, and Enforcement Status. Table 7.1 lists the twelve combinations—
along with the availability of speed data and the total length of roadway for each
combination.
Table 7.1: Combinations of Trunk Highway Type, Speed Limits During the MSMP,
and Enforcement Status (with Availability of Speed Data and Length of Roadway)
Type of
Roadway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
Speed Limits
Increased—from 55
mph to 60 mph
Unchanged at 55
mph
Increased—from 55
mph to 60 mph
4-Lane Divided
Highway
4-Lane Divided
Highway
Unchanged at 65
mph
Unchanged at 65
mph
Rural Freeway
Unchanged at 70
mph
Unchanged at 70
mph
Rural Freeway
Urban Freeway
Urban Freeway
Urban Freeway
Urban Freeway
Urban Freeway
Increased—from 55
mph to 60 mph
Unchanged at 55
mph
Unchanged at 60
mph
Unchanged at 60
mph
Unchanged at 55
mph
Enforcement
Status
(Within/Outside
Enhanced
Enforcement
Zone)
Within
Outside
Outside
Within
Outside
Availability of
Speed Data
Available/
Unavailable
Available
(ATR)
Available
(ATR & Tube)
Available
(Tube)
Total Length of
Highways
Segments
(in Miles)
316.790
Available
(ATR & Tube)
Available
(ATR)
52.219
7,593.783
474.511
550.525
Available
(ATR & Tube)
Available
(ATR)
265.246
27.337
89.397
Within
Available
(ATR)
Available
(ATR)
Unavailable
Outside
Unavailable
73.377
Within
Unavailable
11.234
Within
Outside
Within
Outside
A2-118
459.835
4.052
Table 7.1 shows that crash data were available from all the combinations for which speed
data were available, as well as from three combinations for which no speed data were
available. The table also shows that there were great differences in the length of roadway
in each combination—the range was from 7,593.783 miles of 2-Lane/2-Way Highway,
with unchanged speed limits, that were Outside the enhanced enforcement zones to 4.052
miles of Urban Freeway, with unchanged speed limits, that were Within the enhanced
enforcement zones.
While an enormous amount of speed data was available for analysis purposes, in contrast
there were orders of magnitude less crash data. Since crash data becomes more stable as
the sample size increases, instead of analyzing them for particular road segments, we
analyzed the crash data in terms of the twelve combinations listed in Table 7.1. Also, we
combined the crash data from the First Enhanced Enforcement Period and the First
Regular Enhancement Period. Comparisons of the crash data from the First MSMP Test
Period with historical crash data, combined over the previous five years, for the same
time period (between 9/26 and 12/4) are presented in Tables 7.2 through 7.13
Table 7.2: Crash Data for 2-Lane/2-Way Highways for which the Speed Limit Was
Increased, from 55 mph to 60 mph, and that Were Within the Enhanced
Enforcement Zones during the MSMP
Test Period
(9/26/05 to 12/04/05)
Historical Crash Data
Length (miles)
316.790
316.790
Average Daily Traffic
3,959.0038
3,861.8090
Number of Fatal Crashes
2
7
Number of A Injury
Crashes
2
10
Number of B Injury
Crashes
8
34
Number of C Injury
Crashes and Unknowns
23
40
Number of Property
Damage Crashes
52
279
Total Crashes
87
370
Crash Rate
0.9910
0.8641
Severity Rate
1.5947
1.2518
Fatal Crash Rate
2.2781
1.6348
A2-119
7.3: Crash Data for 2-Lane/2-Way Highways for which the Speed Limit Was
Unchanged, at 55 mph, and that Were Outside the Enhanced Enforcement Zones
during the MSMP
Test Period
(9/26/05 to 12/04/05)
Historical Crash Data
Length (miles)
7,593.783
7,593.783
Average Daily Traffic
2,539.9186
2,454.7033
Number of Fatal Crashes
18
117
Number of A Injury
Crashes
28
172
Number of B Injury
Crashes
130
871
Number of C Injury
Crashes and Unknowns
276
1,161
Number of Property
Damage Crashes
966
5,025
Total Number of Crashes
1,418
7,346
Crash Rate
1.0503
1.1260
Severity Rate
1.5628
1.7218
Fatal Crash Rate
1.3332
1.7933
Table 7.4: Crash Data for 2-Lane/2-Way Highways for which the Speed Limit Was
Increased, from 55 mph to 60 mph, and that Were Outside the Enhanced
Enforcement Zones during the MSMP
Test Period
(9/26/05 to 12/04/05)
Historical Crash Data
474.511
Length (miles)
474.511
2,745.0887
Average Daily Traffic
2,700.2422
1
Number of Fatal Crashes
7
0
Number of A Injury
Crashes
7
3
Number of B Injury
Crashes
27
12
Number of C Injury
Crashes and Unknowns
45
36
Number of Property
Damage Crashes
201
52
Total Crashes
287
0.5703
Crash Rate
0.6400
0.8116
Severity Rate
0.9700
1.0967
Fatal Crash Rate
1.5096
A2-120
Table 7.5: Crash Data for 4-Lane Divided Highways for which the Speed Limit Was
Unchanged, at 65 mph, and that Were Within the Enhanced Enforcement Zones
during the MSMP
Test Period
(9/26/05 to 12/04/05)
Historical Crash Data
52.219
Length (miles)
52.219
16,844.8455
Average Daily Traffic
15,802.3379
1
Number of Fatal Crashes
3
0
Number of A Injury
Crashes
3
2
Number of B Injury
Crashes
25
4
Number of C Injury
Crashes and Unknowns
53
29
Number of Property
Damage Crashes
193
36
Total Crashes
277
0.5847
Crash Rate
0.9591
0.7996
Severity Rate
1.3884
1.6241
Fatal Crash Rate
1.0387
Table 7.6: Crash Data for 4-Lane Divided Highways for which the Speed Limit Was
Unchanged, at 65 mph, and that Were Outside the Enhanced Enforcement Zones
during the MSMP
Test Period
(9/26/05 to 12/04/05)
Historical Crash Data
550.525
Length (miles)
550.525
12,279.2783
Average Daily Traffic
11,655.9877
5
Number of Fatal Crashes
14
9
Number of A Injury
Crashes
42
24
Number of B Injury
Crashes
205
72
Number of C Injury
Crashes and Unknowns
327
273
Number of Property
Damage Crashes
1,456
383
Total Crashes
2,044
0.8094
Crash Rate
0.9093
1.1623
Severity Rate
1.3182
1.0566
Fatal Crash Rate
0.6228
A2-121
Table 7.7: Crash Data for Rural Freeways for which the Speed Limit Was
Unchanged, at 70 mph, and that Were Within the Enhanced Enforcement Zones
during the MSMP
Test Period
(9/26/05 to 12/04/05)
Historical Crash Data
Length (miles)
265.246
265.246
Average Daily Traffic
21,345.3377
19,867.3712
Number of Fatal Crashes
4
14
Number of A Injury
Crashes
4
23
Number of B Injury
Crashes
22
85
Number of C Injury
Crashes and Unknowns
37
179
Number of Property
Damage Crashes
227
929
Total Crashes
294
1,230
Crash Rate
0.7418
0.6669
Severity Rate
1.0168
0.9239
Fatal Crash Rate
1.0093
0.7591
Table 7.8: Crash Data for Rural Freeways for which the Speed Limit Was
Unchanged, at 70 mph, and that Were Outside the Enhanced Enforcement Zones
during the MSMP
Test Period
(9/26/05 to 12/04/05)
Historical Crash Data
Length (miles)
459.835
459.835
Average Daily Traffic
22,663.6713
21,511.1002
Number of Fatal Crashes
3
18
Number of A Injury
Crashes
5
25
Number of B Injury
Crashes
40
183
Number of C Injury
Crashes and Unknowns
86
329
Number of Property
Damage Crashes
367
1,667
Total Crashes
501
2,222
Crash Rate
0.6868
0.6418
Severity Rate
0.9513
0.8850
Fatal Crash Rate
0.4112
0.5199
A2-122
Table 7.9: Crash Data for Urban Freeways for which the Speed Limit Was
Increased, from 55 mph to 60 mph, and that Were Within the Enhanced
Enforcement Zones during the MSMP
Test Period
(9/26/05 to 12/04/05)
Historical Crash Data
27.337
Length (miles)
27.337
Average Daily Traffic
102,733.2401
100,670.8394
Number of Fatal Crashes
2
4
Number of A Injury
Crashes
0
12
Number of B Injury
Crashes
9
71
Number of C Injury
Crashes and Unknowns
43
180
Number of Property
Damage Crashes
138
771
Total Crashes
192
1,038
Crash Rate
0.9767
1.0776
Severity Rate
1.3276
1.4659
Fatal Crash Rate
1.0173
0.4153
Table 7.10: Crash Data for Urban freeways for which the Speed Limit Was
Unchanged, at 55 mph, and that Were Outside the Enhanced Enforcement Zones
during the MSMP
Test Period
(9/26/05 to 12/04/05)
Historical Crash Data
89.397
Length (miles)
89.397
Average Daily Traffic
90,578.2219
89,555.6964
Number of Fatal Crashes
2
10
Number of A Injury
Crashes
1
23
Number of B Injury
Crashes
32
230
Number of C Injury
Crashes and Unknowns
182
749
Number of Property
Damage Crashes
712
3,690
Total Crashes
929
4,702
Crash Rate
1.6390
1.6780
Severity Rate
2.0924
2.1484
Fatal Crash Rate
0.3528
0.3569
A2-123
Table 7.11: Crash Data for Urban Freeways for which the Speed Limit Was
Unchanged, at 60 mph, and that Were Within the Enhanced Enforcement Zones
during the MSMP
Test Period
(9/26/05 to 12/04/05)
Historical Crash Data
4.052
Length (miles)
4.052
Average Daily Traffic
97,906.2409
96,190.5994
Number of Fatal Crashes
0
1
Number of A Injury
Crashes
1
3
Number of B Injury
Crashes
2
8
Number of C Injury
Crashes and Unknowns
2
17
Number of Property
Damage Crashes
17
109
Total Crashes
22
138
Crash Rate
0.7922
1.0116
Severity Rate
1.1163
1.3488
Fatal Crash Rate
0.0000
0.7330
Table 7.12: Crash Data for Urban Freeways for which the Speed Limit Was
Unchanged, at 60 mph, and that Were Outside the Enhanced Enforcement Zones
during the MSMP
Test Period
(9/26/05 to 12/04/05)
Historical Crash Data
73.377
Length (miles)
73.377
Average Daily Traffic
91,627.8252
93,679.0849
Number of Fatal Crashes
1
7
Number of A Injury
Crashes
5
8
Number of B Injury
Crashes
22
140
Number of C Injury
Crashes and Unknowns
87
390
Number of Property
Damage Crashes
356
1,845
Total Crashes
471
2,390
Crash Rate
1.0008
0.9934
Severity Rate
1.3195
1.2935
0.2125
Fatal Crash Rate
0.2910
A2-124
Table 7.13: Crash Data for Urban Freeways for which the Speed Limit Was
Unchanged, at 55 mph, and that Were Within the Enhanced Enforcement Zones
during the MSMP
Test Period
(9/26/05 to 12/04/05) Historical Crash Data
11.234
Length (miles)
11.234
Average Daily Traffic
128,504.4084
125,574.6946
Number of Fatal Crashes
0
3
Number of A Injury Crashes
0
0
Number of B Injury Crashes
7
28
Number of C Injury Crashes
and Unknowns
28
152
Number of Property Damage
Crashes
110
618
Total Crashes
145
801
Crash Rate
1.4349
1.6223
Severity Rate
1.8505
2.0679
Fatal Crash Rate
0.0000
0.0608
Table 7.14summarizes the crash data presented in Tables 7.2 through 7.13. Table 7.14
shows the Crash Rate, Severity Rate, and Fatal Crash Rate for each combination of road
type, speed limit condition both Within and Outside the Enforcement Zones.
Table 7.14: Crash Rate, Severity Rate, and Fatal Crash Rate for Each Combination
of Trunk Highway Type, Speed Limits During the MSMP, and Enforcement Zone
During the First Ten-Week MSMP Period
Within Enforcement Zone
Outside Enforcement Zone
Road Type
Fatal
Fatal
And
Crash Severity Crash
Crash Severity Crash
Speed Limit Condition
Rate
Rate
Rate
Rate
Rate
Rate
2 Lane/2-Way Highway
Increase—55 to 60 mph 0.9910
1.5947
2.2781
0.5703
0.8116
1.0967
2 Lane/2-Way Highway
No Change—55 mph
—
—
—
1.0503
1.5628
1.3332
4 Lane/Divided Highway
No Change—65 mph
0.5847
0.7996
1.6241
0.8094
1.1623
1.0566
Rural Freeway
Unchanged—70 mph
0.7418
1.0168
1.0093
0.6868
0.9513
0.4112
Urban Freeway
Increase—55 to 60 mph 0.9767
1.3276
1.0173
—
—
—
Urban Freeway
No Change—55 mph
1.4349
1.8505
0.0000
1.6390
2.0924
0.3528
Urban Freeway
No Change—60 mph
0.7922
1.1163
0.0000
1.0008
1.3195
0.2125
A2-125
Section 8. Citation Data
During the First MSMP Enhanced Enforcement Period citation data were collected for
the highways on which there was Enhanced Enforcement. In all citation data were
collected for 32 regions; 14 regions have ATRs in them, seven regions will have Tubes in
the Fourth Enhanced Enforcement Period, and the remaining eleven regions are next to
regions where there are ATRs or Tubes. The citation data for the 14 regions in which
there are ATRs are reported in the tables below—there is one table for each road type
included in the MSMP—i.e., 2-Lane/2-Way Highways, 4-Lane Highways, Rural
Freeways, and Urban Highways. The tables list the ATRs that were on the various road
types and their locations. The tables also present the Number of Speed Citations and the
Number of Speed Warnings that were given during the First Enhanced Enforcement
Period, as well as the Number of Vehicles that were Stopped and the Number of Hours of
Enforcement.
Table 8.1: Citation Data for 2-Lane/2-Way Highways on Which ATRs Were
Located
ATR
210
219
220
Location
US-71, 1 m. North of
Blackduck, Beltrami
US-2, South East of
Warba, Itasca
US-71, South of CR 89,
Hubbard
Total
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
137
585
838
250
287
728
1,042
648
253
1,103
1,450
414
677
2,416
3,330
1,312
Table 8.2: Citation Data for 4-Lane Divided Highways on Which ATRs Were
Located
ATR
172
187
188
197
Total
Location
US-10, West of
Dilworth, Clay
US-10, 0.8 miles West
of Rice, Benton
US-52, North of
Rochester, Olmstead
SR-60, 0.7 miles West
of junction with SR-4,
(St. James) Watonwan
*Probably an underestimate
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
93
214
319
175
305
358
716
294
320
368
753
319
175
285
460*
191
893
1,225
2,248*
979
A2-126
Table 8.3: Citation Data for Rural Freeways on Which ATRs Were Located
ATR
175
191
208
227
Location
I-94, 0.5 miles South
East of Saulk Centre,
Stearns
I-35, North of
Wyoming, Chisago
I-35, North of
Owatanna, Steele
I-90, East of Alden,
Freeborn
Total
*Probably an underestimate
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
328
285
658
294
336
175
514
306
205
362
610
216
128
279
423
36*
997
1,101
2,205
852*
Table 8.4: Citation Data for Urban Freeways on Which ATRs Were Located
ATR
100
I94
35WCD
Total
Location
Highway 100, near
Brooklyn Center,
Hennepin
I-94, South of 57th
Street Bridge,
Hennepin
I-35W, near Roseville,
Ramsey
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
424
289
973
306
274
222
607
306
690
412
1,091
306
1,388
923
2,671
918
The citation data for the individual highways that are presented in Tables 8.1 through 8.4
are summarized in Table 8.5. This table presents, for each of the four highway types, the
Number of Speed Citations and the Number of Speed Warnings that were given during
the First Enhanced Enforcement Period, as well as the Number of Vehicles that were
Stopped and the Number of Hours of Enforcement.
A2-127
Table 8.5: Citation Data for the Four Types of Highways on Which ATRs Were
Located
Type of Highway
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
2-Lane/2-Way
Highway
4-Lane Divided
Highway
Rural Freeway
Urban Freeway
677
2,416
3,330
1,312
893
997
1,388
1,225
1,101
923
2,248*
2,205
2,671
979
852*
918
Total
3,955
4,742
10,454*
4,061*
*Probably underestimates
A2-128
Appendix 3
Minnesota Speed Management Project: Deliverable #5—
Data Analysis for the Second Test Period
Kathleen A. Harder, Ph.D. and John R. Bloomfield, Ph.D.
Center for Human Factors Systems Research and Design,
University of Minnesota, Suite 225
1425 University Ave. S.E.
Minneapolis, MN 55414
Contents
Page
Section 1. Introduction …………………………………………………………………..3
1.1 Background ……………………………………………………………….3
1.2 Organization of this Report ……………………………………………..5
Section 2. Summary of Findings during the Second MSMP Test Period
………..…6
2.1 Overall Effect of the MSMP during the Second Enhanced
Enforcement and Second Regular Enforcement Period…………………...6
2.2 Effect of the MSMP on 2-Lane/2-Way Highways …………………………7
2.3 Effect of the MSMP on 4-Lane Divided Highways ………………………10
2.4 Effect of the MSMP on Rural Freeways …………………………………13
2.5 Effect of the MSMP on Urban Freeways ………………………………...15
2.6 Crash Rates During the Second MSMP Period ………………………….18
2.7 Citation Data During the Second MSMP Period ………………………..19
Section 3. Speed Data Obtained on 2-Lane/2-Way Highways …..……………………20
3.1 Speed Data from ATRs Located Within Enhanced
Enforcement Zones ………………………………………………………20
3.2 Speed Data from ATRs Located Outside Enhanced
Enforcement Zones ………………………………………………………33
3.3 Overall Effect of the MSMP on 2-Lane/2-Way Highways ………………50
Section 4. Speed Data Obtained on 4-Lane Divided Highways ….…………………..54
4.1 Speed Data from ATRs Located Within Enhanced
Enforcement Zones ………………………………………………………54
4.2 Speed Data from One ATR Located Outside Enhanced
Enforcement Zones ………………………………………………………72
4.3 Overall Effect of the MSMP on 4-Lane Divided Highways ……………..76
Section 5. Speed Data Obtained on Rural Freeways …………………………………80
5.1 Speed Data from ATRs Located Within Enhanced
Enforcement Zones ………………………………………………………80
5.2 Speed Data from One ATR Located Outside Enhanced
Enforcement Zones ………………………………………………………91
5.3 Overall Effect of the MSMP on Rural Freeways ………………………..95
Section 6. Speed Data Obtained on Urban Freeways ………………………………….99
6.1 Speed Data from ATRs Located Within Enhanced
Enforcement Zones ……………………………………………………100
6.2 Speed Data from One ATR Located Outside Enhanced
Enforcement Zones ……………………………………………………113
6.3 Overall Effect of the MSMP on Urban Freeways ………………………118
Section 7. Crash Data ………………………………………………………………...121
Section 8. Citation Data ………………………………………………………………130
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Section 1. Introduction
1.1 Background
This report contains the results of the analysis of data obtained during the second testing
period of the Minnesota Speed Management Program (MSMP). The Minnesota Speed
Management Program (MSMP) is a cooperative project between the Minnesota
Department of Transportation (Mn/DOT) and the Minnesota Department of Safety
(DPS). The program, which ran from 9/26/05 to 8/13/06, involved:
• Raising the speed limit on select roadways in Minnesota from 55 mph to 60 mph
in order to align the speed limit more closely with the design speed of the
roadways.
• Increasing the presence of enforcement officers along selected areas of these
roadways and other high-design roadways for selected periods of time.
The MSMP involved the following four types of roadway—(1) 2-Lane/2-Way Highways,
(2) 4-Lane Divided Highways, (3) Rural Freeways, and (4) Urban Freeways.
This report presents the University of Minnesota’s assessment of effectiveness of the
MSMP during its second test period, between 12/05/05 and 2/26/06. The test period had
two phases—the Second Enhanced Enforcement Period, lasting eight weeks between
12/05/05 and 1/29/06; and the Second Regular Enforcement Period, lasting four weeks
between 1/30/06 and 2/26/06.
In the Second Enhanced Enforcement Period and the Second Regular Enforcement
Period, we analyzed speed data collected by Mn/DOT in order to determine whether there
were changes in speeds as a result of the MSMP. In addition, we analyzed crash data to
determine whether there were changes in crash rates. Some historical speed data and
crash data were available for comparison purposes—where possible, we compared the
data obtained in these two phases with historical data. Also, we analyzed citation data—
in this case however, there no historical citation data were available.
The speed data that were provided by Mn/DOT were collected from a number of
Automated Traffic Recorders (ATRs). [We expect the ATR data will be augmented by
Tube data in the final test period.] The ATRs are listed in Table 1.1. The ATRs are
organized in the table in terms of the type of roadway at which they are located—i.e.,
whether they are on 2-Lane/2-Way Highways, 4-Lane Divided Highways, Rural
Freeways, or Urban Freeways. The table lists their locations, the speed limit (and
whether or not it was changed for the MSMP), and whether they were located Within or
Outside an Enhanced Enforcement Zone.
A3-3
Table 1.1: ATRs Organized by Road Type
Type of
roadway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
ATR
210
219
220
179
198
199
222
4-Lane Divided
Highway
197
4-Lane Divided
Highway
4-Lane Divided
Highway
4-Lane Divided
Highway
4-Lane Divided
Highway
172
Rural Freeway
175
Rural Freeway
191
Rural Freeway
208
Rural Freeway
227
Rural Freeway
200
Urban Freeway
100
Urban Freeway
I94
Urban Freeway
35WC
D
335
Urban Freeway
187
188
353
Location
US-71, 1 m. North of
Blackduck, Beltrami
US-2, South East of Warba,
Itasca
US-71, South of CR 89,
Hubbard
USTH 59, South of Garvin,
Lyon
USTH 212, East of TH 23,
Chippewa
USTH 75, 0.55 m. N of Co
Rd. 69, Pipestone
MNTH 65, near Pliny,
Aitkin
Speed limit
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Unchanged at 55 mph
Within/
Outside
Enforcement
Zone
Within
Within
Within
Outside
Unchanged at 55 mph
Outside
Unchanged at 55 mph
Outside
Unchanged at 55 mph
Outside
SR-60, 0.7 miles West of
junction with SR-4, (St.
James) Watonwan
US-10, West of Dilworth,
Clay
US-10, 0.8 miles West of
Rice, Benton
US-52, North of Rochester,
Olmstead
TH 169, South of CR
59,North of Jordan, Scott
Unchanged at 65 mph
Within
Unchanged at 65 mph
Within
Unchanged at 65 mph
Within
Unchanged at 65 mph
Within
Unchanged at 65 mph
Outside
I-94, 0.5 miles South East
of Saulk Centre, Stearns
I-35, North of Wyoming,
Chisago
I-35, North of Owatanna,
Steele
I-90, East of Alden,
Freeborn
I-94, Hasty, Wright
Unchanged at 70 mph
Within
Unchanged at 70 mph
Within
Unchanged at 70 mph
Within
Unchanged at 70 mph
Within
Unchanged at 70 mph
Outside
Highway 100, near
Brooklyn Center, Hennepin
I-94, South of 57th Street
Bridge, Hennepin
I-35W, near Roseville,
Ramsey
I-35W at County Road 53,
Anoka
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Unchanged at 55 mph
Within
A3-4
Within
Within
Outside
From the speed data obtained with the ATRs, we derived several speed measures for the
Second Enhanced Enforcement Period and Second Regular Enforcement Period. The
same measures were also derived from historical speed data that were obtained during the
same calendar time periods. Where possible, we used historical speed data from the three
years prior to the MSMP. In order to compare the MSMP speed data with the historical
data, we conducted a series of statistical tests in which the following measures were
compared—(1) the mean speed, (2) the percentage of vehicles in the 10 mph pace, (3) the
proportion of vehicles traveling at 65 mph or more, (4) the proportion of vehicles
traveling at 70 mph or more, (5) the proportion of vehicles traveling at 75 mph or more,
(6) the proportion of vehicles traveling at 80 mph or more, and (7) the proportion of
vehicles traveling at 85 mph or more. [Please note that in addition, we derived the
following measures—(8) median speed, (9) 15th percentile, (10) 85th percentile, (11) 90th
percentile (12) 95th percentile, and (13) the total number of vehicles—though we did not
conduct statistical comparisons for the median speed or the percentile measures. We did
not conduct statistical analyses for these measures because the comparisons are not valid.
The speed data from which they are derived are collected in one 40-mph bin (from 0.01
mph to 40.00 mph), nine 5-mph bins (40.01 mph to 45.00 mph, 45.01 mph to 50.00 mph;
50.01 mph to 55.00 mph; 55.01 mph to 60.00 mph; 60.01 mph to 65.00 mph; 65.01 mph
to 70.00 mph; 70.01 mph to 75.00 mph; 75.01 mph to 80.00 mph; and 80.01 mph to
85.00 mph), and one 15-mph bin (from 85.01 mph to 100.00 mph) and no differentiation
within the bins is possible, which makes a statistical analysis invalid.]
To test for differences in the mean speeds we used the procedure for comparing
population means outlined by Kitchens (1987, p 369-373). For the comparisons
involving the percentage of vehicles in the 10 mph pace and proportions of vehicle
traveling at various speeds, we treated each distribution of speeds as a Bernoulli
population—i.e., a population in which each element is one of two possibilities, in this
case, (1) in or out of the 10 mph pace, or (2) above or below a selected speed (e.g., 75
mph). We then used the procedure for comparing population proportions described by
Kitchens (1987, pages 400-404). The statistical tests were conducted in two ways. First,
we conducted the tests in the traditional way, using n-values that were equal to the
number of vehicles that traveled by each ATRs in the test periods under consideration. In
the second, we used an extremely conservative correction, with n-values that were equal
to the number of hours in each test period—because it is likely that, when traffic is
congested, individual vehicles may travel at speeds which are not independent of each
other.
1.2 Organization of this Report
The next section of this report, Section 2, presents summary data. Then, detailed
analyses are presented in subsequent sections of the report. There is a section for each of
the four road types, with analyses of the speed data obtained at each of the ATRs listed in
Table 1.1. The final two sections of this report deal with crash data and citation data.
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Section 2: Summary of Findings during the Second MSMP Test Period
In the MSMP, we obtained speed data from 21 ATRs located throughout Minnesota.
Fourteen of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining seven were located Outside Enhanced Enforcement Zones. Seven ATRs were
located on 2-Lane 2-Way Highways, five were located on 4-Lane Divided Highways,
five on Rural Freeways, and four on Urban Freeways. The effect of the MSMP on the
speed data obtained at these ATRs is summarized in this section of the report.
2.1. Overall Effect of the MSMP during the Second Enhanced and Regular Enforcement
Periods
To provide a brief overall summary of the effect of the MSMP during the Second
Enhanced Enforcement Period on driving speeds, we focused on vehicles traveling at
least 10 mph above the speed limit at the locations of the ATRs Within the Enhanced
Enforcement Zones during the MSMP. [It should be noted that, on the 2-Lane/2-Way
Highways and the Urban Freeways, at the locations Within the Enhanced Enforcement
Zones the speed limits were increased from 55 mph to 60 mph, while at the locations
Outside the Enhanced Enforcement Zones the speed limits were unchanged at 55mph.
Also, the speed limits remained unchanged at 65 mph on 4-Lane Divided Highways and
at 70 mph on Rural Freeways.]
Table 2.1 shows the decrease or increase in the percentage of the vehicles traveling at
least 10 mph above the speed limit during the Second Enhanced Enforcement Period and
the Second Regular Enforcement Periods as compared to the percentages traveling at
those speeds before the MSMP was implemented. This means that, for the ATRs located
on the 2-Lane 2-Way Highways and the Urban Freeways, the percentages shown are for
vehicles traveling at 70 mph or more (10 mph above the new speed limit and 15 mph
above the pre-MSMP speed limit); while for the ATRs located on the 4-Lane Divided
Highways, the percentages shown are for vehicles traveling at 75 mph or more; and for
the ATRs located on the Rural Freeways, the percentages shown are for vehicles
traveling at 80 mph or more.
A3-6
Table 2.1: Summary of the Effect of the MSMP on the Percentage of Vehicles
Traveling at Least 10 mph Above the Speed Limits during the MSMP
Road type
Within the Enhanced Enforcement
Zones
Increase/
Increase/
Decrease during Decrease during
Second Regular
Second
Enforcement
Enhanced
Period
Enforcement
Period
Outside the Enhanced Enforcement
Zones
Increase/
Increase/
Decrease during Decrease during
Second Regular
Second
Enforcement
Enhanced
Period
Enforcement
Period
2-Lane 2-Way
-18.18%
-35.19%
+68.25%
+40.31%
Highways
4-Lane Divided
-12.81%
-19.13%
-22.46%*
-35.82%*
Highways
Rural
-50.00%
-46.69%
-71.55%*
-72.74%*
Freeways
Urban
-14.28%**
-3.87%**
-6.52%*
-9.74%*
Freeways
*Speed data from one ATR located close to Enhanced Enforcement Zones.
**Historical speed data used in comparisons obtained just before the start of the MSMP.
Table 2.1 shows that, for the highways with ATRs located Within the Enhanced
Enforcement Zones, there were decreases in the percentages of vehicles traveling at least
10 mph above the speed limits. The table also shows that, with one exception, for the
highways with ATRs located Outside the Enhanced Enforcement Zones, there were also
decreases in the percentage of vehicles traveling at least 10 mph above the speed limits
Within the Enhanced Enforcement Zones. The exception was for the 2-Lane 2-Way
Highways (for which there were four ATRs Outside the Enhanced Enforcement Zones).
It should be noted that for the other three road types, there was a single ATR Outside the
Enhanced Enforcement Zones—and that, in each case, the ATR was located relatively
close to one, or two, Enhanced Enforcement Zones.
The data from which Table 2.1 was derived for each of the four road types is presented in
more detail in the remainder of the section of the report.
2.2. Effect of the MSMP on 2-Lane 2-Way Highways
In the MSMP, we obtained speed data from seven ATRs located on 2-Lane 2-Way
Highways—three of these ATRs were located Within Enhanced Enforcement Zones,
while the remaining four were located Outside Enhanced Enforcement Zones. The speed
limit was increased from 55 mph to 60 mph at the locations of the three ATRs Within
Enhanced Enforcement Zones, while the speed limit remained unchanged at 55 mph at
the locations of the four ATRs Outside Enhanced Enforcement Zones.
In order to provide a brief overall summary of the effect of the MSMP, we focused on
drivers traveling at least 10 mph above the new speed limit. We combined the speed data
A3-7
from the three ATRs Within Enhanced Enforcement Zones. Then, we compared speed
data from the Test Year with data from the previous year—when the speed limit at the
locations of the three ATRs was still 55 mph. Table 2.2 shows the results of this
comparison for the Second Enhanced Enforcement Period.
Table 2.2: Effect of MSMP on 2-Lane 2-Way Highways during the Second
Enhanced Enforcement Period at Three ATRs Within Enhanced Enforcement Zones
Sample Total
281,674*
Sample Total
285,062**
One Year Before MSMP
# Over 70 mph
8,662*
Second Enhanced Enforcement Period
# Over 70 mph
7,175**
% Over 70 mph
3.08*
% Over 70 mph
2.52**
Result: 18.18% Decrease in Drivers Traveling Over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-219 during the time period
**Numbers adjusted to account for limited availability of data from ATR-210 during the time period
Table 2.2 indicates that, for the three ATRs Within Enhanced Enforcement Zones on 2Lane 2-Way Highways, during the Second Enhanced Enforcement Period, there was a
18.18% decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the
new speed limit.
A similar comparison was conducted for the Second Regular Enforcement Period. The
results of this comparison are shown in Table 2.3.
Table 2.3: Effect of MSMP on 2-Lane 2-Way Highways during Second Regular
Enforcement Period at Enforcement Period at Three ATRs Within Enhanced
Enforcement Zones
Sample Total
152,856*
Sample Total
141,937
One Year Before MSMP
# Over 70 mph
7,117*
Second Regular Enforcement Period
# Over 70 mph
4,289
% Over 70 mph
4.66*
% Over 70 mph
3.02
Result: 35.19% Decrease in Drivers Traveling Over 70 mph
*Data for ATR-210 and ATR-220 from one year earlier; data from ATR-219 from two years earlier.
Table 2.3 shows that, for the three ATRs Within Enhanced Enforcement Zones on 2-Lane
2-Way Highways, during the Second Regular Enforcement Period, there was a 35.19%
reduction in the number of drivers traveling over 70 mph—i.e., 10 mph over the speed
limit.
A3-8
We also examined the speed data obtained from the four ATRs Outside Enhanced
Enforcement Zones, where there was no change in the level of enforcement during the
MSMP and no change in the speed limit. We compared this data with speed data from
the previous year, when the speed limit at the locations of the three ATRs was still 55
mph. For comparison purposes, we focused on drivers traveling at 70 mph or more—
while this is 10 mph above the new speed limit Within Enhanced Enforcement Zones, it is
15 mph above the actual speed limit at the locations of the four ATRs Outside Enhanced
Enforcement Zones. The results of this comparison for speed data obtained during the
Second Enhanced Enforcement Period are shown in Table 2.4.
Table 2.4: Effect of MSMP on 2-Lane 2-Way Highways during the Second
Enhanced Enforcement Period at Four ATRs Outside Enhanced Enforcement Zones
Sample Total
359,877
Sample Total
363,949
One Year Before MSMP
# Over 70 mph
7,598
Second Enhanced Enforcement Period
# Over 70 mph
12,931
% Over 70 mph
2.11
% Over 70 mph
3.55
Result: 68.25% Increase in Drivers Traveling Over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-199 during the time period
Table 2.4 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on 2-Lane 2-Way Highways, during the Second Enhanced Enforcement Period, there was
a 68.25% increase in the number of drivers traveling over 70 mph—i.e., 10 mph above
the new speed limit Within Enhanced Enforcement Zones (and 15 mph above the current
speed limit Outside the Enhanced Enforcement Zones).
A similar comparison was conducted for the Second Regular Enforcement Period. The
results of this comparison using speed data from the four ATRs located Outside
Enhanced Enforcement Zones are shown in Table 2.5.
Table 2.5: Effect of MSMP on 2-Lane 2-Way Highways during the Second Regular
Enforcement Period at Four ATRs Outside Enhanced Enforcement Zones
Sample Total
176,877*
Sample Total
176,285
One Year Before MSMP
# Over 70 mph
4,555*
Second Regular Enforcement Period
# Over 70 mph
6,383
% Over 70 mph
2.58*
% Over 70 mph
3.62
Result—40.31% Increase in Drivers Traveling over 70 mph
*Data for ATR-179, ATR-198, and ATR-222 from one year earlier; data from ATR-199 from two years
earlier.
A3-9
Table 2.5 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on the 2-Lane 2-Way Highways, during the Second Regular Enforcement Period there
was a 40.31% increase in the number of drivers traveling over 70 mph—i.e., at 10 mph
over the new speed limit Within Enhanced Enforcement Zones (and 15 mph above the
current speed limit Outside Enhanced Enforcement Zones).
Comparisons between speed data from the ATRs located Within Enhanced Enforcement
Zones and the ATRs located Outside Enhanced Enforcement Zones should be treated
with caution. It should be noted that the three ATRs located Within Enhanced
Enforcement Zones are all in Northern Minnesota, and that the proportion of vehicles
traveling at 70 mph or more for them ranges between 0.012 and 0.039 during the Second
MSMP time period. In contrast, the four ATRs located Outside Enhanced Enforcement
Zones are more widely spread, with three in South Western Minnesota and one in East
Central Minnesota. For these four ATRs, the there is a much greater range in the
proportion of vehicles traveling at 70 mph or more—the proportion varies between
0.0015, for ATR-179—one of the three ATRs in South Western Minnesota—and 0.170
for ATR-222—which is located in East Central Minnesota.
2.3. Effect of the MSMP on 4-Lane Divided Highways
In the MSMP, we obtained speed data from five ATRs located on 4-Lane Divided
Highways. Four of these ATRs were located Within Enhanced Enforcement Zones, while
the remaining ATR was located Outside the Enhanced Enforcement Zones. At the
locations of the four ATRs Within the Enhanced Enforcement Zones and the ATRs
Outside the Enhanced Enforcement Zones, the speed limit was unchanged—at 65mph—
during the MSMP.
In order to provide a brief overall summary of the effect of the MSMP, we focused on
drivers traveling at least 10 mph above the speed limit—i.e., on drivers traveling at 75
mph or more speed data from the four ATRs Within Enhanced Enforcement Zones were
combined. Then, we compared speed data from the Test Year with data from previous
years—in the case of ATR-172, ATR-187, and ATR-188 the data are from one year
earlier, while the data for ATR-197 are from three years earlier. Table 4.21 shows the
results of this comparison for the Second Enhanced Enforcement Period.
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Table 2.6: Effect of MSMP on 4-Lane Divided Highways during the Second
Enhanced Enforcement Period at Four ATRs Within Enhanced Enforcement Zones
Sample Total
3,327,475*
Sample Total
3,387,518**
Pre-MSMP
# Over 75 mph
202563*
Second Enhanced Enforcement Period
# Over 75 mph
179,741**
% Over 75 mph
6.09*
% Over 75 mph
5.31**
Result: 12.81% Decrease in Drivers Traveling Over 75 mph
*Numbers adjusted to account for limited availability of data from ATR-188. Also, data for ATR-172,
ATR-187, and ATR-188 are from one year earlier; data for ATR-197 are from three years earlier.
**Numbers adjusted to account for limited availability of data from ATR-187.
Table 2.6 indicates that, for the four ATRs located Within Enhanced Enforcement Zones
on 4-Way Divided Highways, during the Second Enhanced Enforcement Period, there
was a 12.81% decrease in the number of drivers traveling over 75 mph—i.e., 10 mph
over the speed limit.
A similar comparison was conducted for the Second Regular Enforcement Period. In this
case, the data for ATR-172 and ATR-188 are from one year earlier, the data for ATR-187
are from two years earlier, and data for ATR-187 are from three years earlier. The results
of the comparison are shown in Table 4.22.
Table 2.7: Effect of MSMP on 4-Lane Divided Highways during Second Regular
Enforcement Period at Four ATRs Within Enhanced Enforcement Zones
Sample Total
1,640,680*
Sample Total
1,660,345**
Pre-MSMP
# Over 75 mph
116,668*
Second Regular Enforcement Period
# Over 75 mph
95,581**
% Over 75 mph
7.11*
% Over 75 mph
5.75**
Result—19.13% Decrease in Drivers Traveling Over 75 mph
* Data for ATR-172 and ATR-188 are from one year earlier; data for ATR-187 is from two years earlier;
and data for ATR-187 are from three years earlier.
**Numbers adjusted because, for ATR-197, comparison data were from a 2-week time period.
Table 2.7 shows that, for the ATRs Within Enhanced Enforcement Zones on 4-Way
Divided Highways, during the Second Regular Enforcement Period there was a 19.13%
reduction in the number of drivers traveling over 75 mph—i.e., 10 mph or more above
the speed limit.
A3-11
We also examined the speed data obtained from the four ATRs Outside Enhanced
Enforcement Zones, where there was no change in the level of enforcement during the
MSMP and no change in the speed limit. We compared this data with speed data from
the previous year. For comparison purposes, we again focused on drivers traveling at 75
mph or more—10 mph above the speed limit. The results of this comparison for speed
data obtained during the Second Enhanced Enforcement Period are shown in Table 2.8.
Table 2.8: Table 2.24: Effect of MSMP at One ATR Outside the Enhanced
Enforcement Zones on a 4-Way Divided Highway During the Second Enhanced
Enforcement Period
Sample Total
1,091,536
Sample Total
1,110,074
One Year Before MSMP
# Over 75 mph
45,218
Second Enhanced Enforcement Period
# Over 75 mph
35,614
% Over 75 mph
4.14
% Over 75 mph
3.21
Result: 22.46% Decrease in Drivers Traveling Over 75 mph
Table 2.8 shows that, for the single ATR located Outside the Enhanced Enforcement
Zones on a 4-Way Divided Highway, during the Second Enhanced Enforcement Period,
there was a 22.46% decrease in the number of drivers traveling over 75 mph—i.e., 10
mph or more above the speed limit.
A similar comparison was conducted for the Second Regular Enforcement Period. The
results of this comparison are shown in Table 2.9
Table 2.9: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on a 4-Way Divided Highway During the Second Regular Enforcement Period
Sample Total
565,973
Sample Total
558,792
One Year Before MSMP
# Over 75 mph
27,330
Second Regular Enforcement Period
# Over 75 mph
17,309
% Over 75 mph
4.83
% Over 75 mph
3.10
Result—35.82% Decrease in Drivers Traveling over 75 mph
Table 2.9 shows that, for the ATR located Outside the Enhanced Enforcement Zones on a
4-Way Divided Highway, during the Second Regular Enforcement Period there was a
35.82% decrease in the number of drivers traveling over 75 mph—i.e., at 10 mph over
the speed limit.
A3-12
Comparisons between speed data from the ATRs located Within Enhanced Enforcement
Zones and the ATR located Outside the Enhanced Enforcement Zones should be treated
with caution. The four ATRs located Within Enhanced Enforcement Zones are scattered
throughout Minnesota; while the single ATR Outside the Enhanced Enforcement Zones
is located a few miles to the South-West of the Twin Cities—and many of the drivers
traveling past this ATR may have traveled through Enhanced Enforcement Zones in the
Cities.
2.4. Effect of the MSMP on Rural Freeways
In the MSMP, we obtained speed data from five ATRs located on Rural Freeways—four
of these ATRs were located Within Enhanced Enforcement Zones, while the remaining
ATR was located Outside the Enhanced Enforcement Zones. At the locations of all five
ATRs the speed limit remained unchanged at 70 mph.
In order to provide a brief overall summary of the effect of the MSMP, we compared this
data with speed data from the previous year, focusing on drivers traveling at least 10 mph
above the speed limit—i.e., those traveling at 80 mph or more. The speed data from the
ATRs Within Enhanced Enforcement Zones were combined. In this case, we were able
to combine speed data from ATR-175 and ATR-227—the speed data from ATR-191 and
ATR-208 were unreliable for this period. Table 2.10 shows the results of this comparison
for the Second Enhanced Enforcement Period.
Table 2.10: Effect of MSMP on Rural Freeways during the Second Enhanced
Enforcement Period at Two ATRs (ATR-175 and ATR-227) Within Enhanced
Enforcement Zones
Sample Total
1,358,128*
Sample Total
1,465,562**
One Year Before MSMP
# Over 80 mph
70,884*
Second Enhanced Enforcement Period
# Over 80 mph
38,286**
% Over 80 mph
5.22*
% Over 80 mph
2.61**
Result: 50.00% Decrease in Drivers Traveling over 80 mph
*Numbers adjusted to account for limited availability of data from ATR-227 during the time period
**Numbers adjusted to account for limited availability of data from ATR-175 during the time period
Table 2.10 indicates that, for two of the ATRs Within Enhanced Enforcement Zones on
Rural Freeways, during the Second Enhanced Enforcement Period, there was a 50.00%
decrease in the number of drivers traveling at over 80 mph—i.e., 10 mph over the speed
limit—as compared to the same time period one year before the MSMP was
implemented.
A3-13
A similar comparison was conducted for the Second Regular Enforcement Period. For
this comparison speed data were available from ATR-175 and ATR-227—the speed data
for ATR-191 and ATR-208 were not reliable. The results of this comparison using speed
data from the two ATRs are shown in Table 2.11.
Table 2.11: Effect of MSMP on Rural Freeways During the Second Regular
Enforcement Period at Three ATRs (ATR-175 and ATR-227) Within Enhanced
Enforcement Zones
Sample Total
706,664
Sample Total
689,857*
One Year Before MSMP
# Over 80 mph
40,580
Second Regular Enforcement Period
# Over 80 mph
18,492*
% Over 80 mph
5.74
% Over 80 mph
2.68*
Result: 46.69% Decrease in Drivers Traveling over 80 mph
*Numbers adjusted to account for limited availability of data from ATR-175 during the time period
Table 2.11 indicates that, for two of the ATRs located Within Enhanced Enforcement
Zones on Rural Freeways, during the Second Regular Enforcement Period, there was a
46.69% decrease in the number of drivers traveling over 80 mph—i.e., 10 mph over the
speed limit.
We also examined the difference between the speed data obtained during the Test Periods
from the ATR that was located Outside the Enhanced Enforcement Zones. We compared
this data with speed data from the previous year, focusing on drivers traveling at 80 mph
or more—10 mph above the speed limit. The results of this comparison for speed data
obtained during the Second Enhanced Enforcement Period are shown in Table 2.12.
Table 2.12: Effect of the MSMP on one ATR Outside the Enhanced Enforcement
Zones on a Rural Freeway During the Second Enhanced Enforcement Period
Pre-MSMP Speed Data from 4/24/05 to 5/21/05
# Over 80 mph
% Over 80 mph
182,044
15.08
Second Enhanced Enforcement Period
Sample Total
# Over 80 mph
% Over 80 mph
1,970,991
84,546
4.29
Sample Total
1,206,904
Result: 71.55% Decrease in Drivers Traveling over 80 mph
Table 2.12 shows that, for the ATR located Outside Enhanced Enforcement Zones on a
Rural Freeway, during the Second Enhanced Enforcement Period, there was a 71.55%
decrease in the number of drivers traveling over 80 mph.
A3-14
A similar comparison was conducted for the Second Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 2.13.
Table 2.13: Effect of MSMP at one ATR Outside the Enhanced Enforcement Zones
on a Rural Freeway During the Second Regular Enforcement Period
Pre-MSMP Speed Data from 4/24/05 to 5/21/05
# Over 80 mph
% Over 80 mph
182,044
15.08
Second Regular Enforcement Period
Sample Total
# Over 80 mph
% Over 80 mph
941,792
38,663
4.11
Sample Total
1,206,904
Result: 72.74% Decrease in Drivers Traveling over 80 mph
Table 2.13 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
a Rural Freeway, during the Second Regular Enforcement Period there was a 72.74%
decrease in the number of drivers traveling over 80 mph, as compared to speed data
obtained between 4/24/05 and 5/21/05 before the MSMP was implemented.
For Rural Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
Zones should be treated with caution. The ATR Outside the Enhanced Enforcement
Zones is located between two Enhanced Enforcement Zones—one to the North-West; the
other to the South-East. It is likely that most drivers passing this ATR will have traveled
through one or other of these Enhanced Enforcement Zones. [It should also be noted that
there are no other ATRs Outside the Enhanced Enforcement Zones on Rural Freeways
that could have been considered for comparison purposes for this study.] Also, the speed
data used in the comparisons for the ATR located Outside the Enhanced Enforcement
Zones was from a different time period (4/24/05 to 5/21/05) to the time periods for the
Second Enhanced Enforcement Period (12/5 to 1/29) and the Second Regular
Enforcement Period (1/30 to 2/26).
2.5. Effect of the MSMP on Urban Freeways
In the MSMP, we obtained speed data from four ATRs located on Urban Freeways—
three of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining ATR was located Outside the Enhanced Enforcement Zones. The speed limit
was increased from 55 mph to 60 mph at the locations of the three ATRs Within
Enhanced Enforcement Zones, while the speed limit remained unchanged at 55 mph at
location of the ATR Outside the Enhanced Enforcement Zones
A3-15
In order to provide a brief overall summary of the effect of the MSMP, we focused on
drivers traveling at least 10 mph above the new speed limit. The speed data from the
three ATRs Within Enhanced Enforcement Zones were combined. Then, we compared
speed data collected during the Second Enhanced Enforcement Period with pre-MSMP
speed data that were collected just before the Enhanced Enforcement began—this data
was collected two weeks during September 2005 for ATR-100, and four weeks during
August and September 2005 for ATR-I94 and ATR-35WCD. When the pre-MSMP data
were collected the speed limit at the locations of the three ATRs was still 55 mph. Table
2.14 shows the results of this comparison for the Second Enhanced Enforcement Period.
Table 2.14: Effect of MSMP on Urban Freeways during the Second Enhanced
Enforcement Period at Three ATRs Within Enhanced Enforcement Zones
Sample Total
8,619,318*
Sample Total
16,444,220
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879*
Second Enhanced Enforcement Period
# Over 70 mph
1,786,587
% Over 70 mph
12.67*
% Over 70 mph
10.86
Result: 14.28% Reduction in Drivers over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-100 during the pre-MSMP time
period
Table 2.14 indicates that, for the three ATRs Within Enhanced Enforcement Zones on
Urban Freeways, during the Second Enhanced Enforcement Period, there was a 14.28%
decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the new
speed limit—as compared to the month before the MSMP was implemented.
A similar comparison was conducted for the Second Regular Enforcement Period. The
results of this comparison using speed data from the three ATRs are shown in Table 2.15.
Table 2.15: Effect of MSMP on Urban Freeways during the Second Regular
Enforcement Period at Three ATRs Within Enhanced Enforcement Zones
Sample Total
8,619,318*
Sample Total
8,303,620
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879*
Second Regular Enforcement Period
# Over 70 mph
1,011,164
% Over 70 mph
12.67*
% Over 70 mph
12.18
Result: 3.87% Reduction in Drivers over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-100 during the pre-MSMP time
period
A3-16
Table 2.15 indicates that, for the three ATRs located Within Enhanced Enforcement
Zones on Urban Freeways, during the Second Regular Enforcement Period, there was a
3.87% decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the
new speed limit—as compared to the month before the MSMP was implemented.
We also examined the difference between the speed data obtained during the Test Periods
from the ATR that was located Outside the Enhanced Enforcement Zones. For this ATR
location there was no change in the level of enforcement during the MSMP and no
change in the speed limit. We compared the data obtained during the Test Periods with
speed data from the previous year. For comparison purposes, we focused on drivers
traveling at 70 mph or more—while this is 10 mph above the new speed limit Within
Enhanced Enforcement Zones, it is 15 mph above the actual speed limit at the location of
the ATR Outside Enhanced Enforcement Zones. The results of this comparison for speed
data obtained during the Second Enhanced Enforcement Period are shown in Table 2.16.
Table 2.16: Effect of MSMP at one ATR Outside the Enhanced Enforcement Zones
on an Urban Freeway during the Second Enhanced Enforcement Period
Sample Total
2,179,324
Sample Total
2,181,300
One Year Before MSMP
# Over 70 mph
1,156,395
Second Enhanced Enforcement Period
# Over70 mph
1,081,875
% Over 70 mph
53.06
% Over 70 mph
49.60
Result: 6.52% Decrease in Drivers Traveling over 70 mph
Table 2.16 shows that, for the ATR located Outside Enhanced Enforcement Zones on an
Urban freeway, during the Second Enhanced Enforcement Period, there was a 6.52%
decrease in the number of drivers traveling over 70 mph—i.e., 10 mph above the new
speed limit Within Enhanced Enforcement Zones (and 15 mph above the current speed
limit Outside the Enhanced Enforcement Zones).
A similar comparison was conducted for the Second Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 2.17.
Table 2.17: Effect of MSMP at one ATR Outside the Enhanced Enforcement Zones
on an Urban Freeway during the Second Regular Enforcement Period
Sample Total
1,133,251
Sample Total
1,105,817
One Year Before MSMP
# Over 70 mph
677,070
Second Regular Enforcement Period
# Over 70 mph
596,391
A3-17
% Over 70 mph
59.75
% Over 70 mph
53.93
Result: 9.74% Decrease in Drivers Traveling over 70 mph
Table 2.17 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
an Urban Freeway, during the Second Regular Enforcement Period there was a 9.74%
decrease in the number of drivers traveling over 70 mph—i.e., at 10 mph or more above
the new speed limit Within Enhanced Enforcement Zones (and 15 mph or more above the
current speed limit Outside Enhanced Enforcement Zones).
For Urban Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
Zones should be treated with caution. It should be noted that the location of ATR that
was located Outside the Enhanced Enforcement Zones is only a few miles to the North of
an Enforced Enforcement Zone. And, most of the drivers traveling North past this ATR
will have traveled through that Enhanced Enforcement Zone. [It should also be noted
that, the locations of all the other ATRs Outside the Enhanced Enforcement Zones on
Urban Freeways that might have been considered for comparison purposes for this study
are also very close to Enhanced Enforcement Zones.]
2.6. Crash Rates During the First and Second MSMP Periods
During the First and Second MSMP Test Periods, crash data were available for all
Minnesota trunk highways. These trunk highways included 2-Lane/2-Way Highways, 4Lane Highways, Rural Freeways, and Urban Highways. Some of these highways had
changes in speed limits during the MSMP, some had enhanced enforcement during the
MSMP, and speed data were available from some of them. In all, there were twelve
combinations of Road Type, Speed Limits, and Enforcement Status. Table 2.18 lists the
Crash Rate, the Severity Rate, and the Fatal Crash Rate for each of these combinations
during the first 22 weeks of the MSMP.
A3-18
Table 2.18: Crash Rate, Severity Rate, and Fatal Crash Rate for Each Combination
of Trunk Highway Type, Speed Limits During the MSMP, and Enforcement Zone
During the First 22-Weeks of the MSMP
Road Type/Speed Limit
2 Lane/2-Way Highway
Increase—55 to 60 mph
2 Lane/2-Way Highway
No Change—55 mph
4 Lane/Divided Highway
No Change—65 mph
Rural Freeway
Unchanged—70 mph
Urban Freeway
Increase—55 to 60 mph
Urban Freeway
No Change—55 mph
Urban Freeway
No Change—60 mph
Within
Crash
Rate
Severity
Rate
Fatal
Crash
Rate
0.9889
1.5843
1.5533
—
—
0.7751
Outside
Crash
Rate
Severity
Rate
Fatal
Crash
Rate
0.6979
1.0369
0.9970
—
0.9693
1.4423
1.2457
1.1295
0.7382
0.7848
1.1219
0.6724
0.8946
1.2364
0.6881
0.6947
0.9677
0.2492
0.9942
1.3434
0.4624
—
—
—
1.4889
1.9567
0.0000
1.5846
2.0120
0.5613
0.8184
1.0803
0.0000
0.9842
1.2797
0.09666
2.7. Citation Data During the Second Enhanced Enforcement Period
During the Second MSMP Enhanced Enforcement Period citation data were collected for
all the highways on which there was Enhanced Enforcement. These data are summarized
in Table 2.19. The table presents, for each of the four highway types in the MSMP, the
Number of Speed Citations and the Number of Speed Warnings that were given during
the Second Enhanced Enforcement Period, as well as the Number of Vehicles that were
Stopped and the Number of Hours of Enforcement.
Table 2.19: Citation Data for the Four Types of Highways on Which ATRs Were
Located
Number of
Speed Citations
Number of
Speed Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
475
1,774
2,551
1,754
753
758
1,472
1,180
882
505
2,113*
1,792
2,585
1,439
1,375
1,757
3,458
Total
*Probably an underestimate
4,341
9,041*
6,325
Type of
Highway
2-Lane/2-Way
Highway
4-Lane Divided
Highway
Rural Freeway
Urban Freeway
A3-19
Section 3. Speed Data Obtained on 2-Lane/2-Way Highways
We obtained speed data from seven ATRs that were located on 2-Lane 2-Way Highways.
Three of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining four were located Outside Enhanced Enforcement Zones. During the MSMP,
at the locations of the three ATRs Within the Enhanced Enforcement Zones, the speed
limit was increased from 55 mph to 60 mph and there was Enhanced Enforcement at
various times. In contrast, at the locations of the four ATRs Outside the Enhanced
Enforcement Zones, the speed limit remained unchanged at 55 mph and there was no
change in the enforcement level during the MSMP.
In this section of the report, for the ATRs located Within Enhanced Enforcement Zones
and the ATRs located Outside Enhanced Enforcement Zones, we present comparisons of
the speed data obtained during the Test Year with the speed data obtained at those same
ATRs in the three years prior to the MSMP. Comparisons using the speed data from the
ATRs located Within Enhanced Enforcement Zones are presented first. Then, we present
comparisons using the speed data from the ATRs located Outside Enhanced Enforcement
Zones.
In making the comparisons between the speed data obtained during the Test Year and the
speed data obtained prior to the MSMP, we used two statistical tests. The first test was
used to examine differences in the mean speeds—for this test we used the procedure for
comparing population means outlined by Kitchens (1987, p 369-373). The second test
was used to explore differences in the percentage of vehicles in the 10 mph pace and in
the differences in the proportions of vehicle traveling at various speeds. For this test, we
treated the distribution of speeds as a Bernoulli population—i.e., a population in which
each element is one of two possibilities, in this case, (1) in or out of the 10 mph pace, or
(2) above or below a selected speed (e.g., 75 mph). We then used the procedure for
comparing population proportions described by Kitchens (1987, pages 400-404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
ATR in the time periods under consideration. Second, the tests were conducted using an
extremely conservative correction, with n-values equal to the number of hours in each
test period—the rationale for this was that it is possible, when traffic is congested, that
individual vehicles may travel at speeds which are not independent of each other.
3.1. Speed Data from ATRs located Within Enhanced Enforcement Zones
The three ATRs located Within Enhanced Enforcement Zones on 2-Lane 2-Way
Highways were as follows: (1) ATR-210, on US-71, near Blackduck in Beltrami County,
(2) ATR-219, on US-2, near Warba in Itasca County, and (3) ATR-220, on US-71, South
of CR 89 in Hubbard County. At the locations of all three of these ATRs, the speed limit
was increased from 55 mph to 60 mph during the MSMP. The effect of the MSMP on
A3-20
the speed data at each of these three ATRs is reported in this section. It is reported ATR
by ATR—with the effect of the MSMP in the Second Enhanced Enforcement Period
followed by its effect in the Second Regular Enhancement Period.
For each of the three ATRs Within Enhanced Enforcement Zones, two tables are
presented for each time period. In the first of these tables, speed data from the Test Year
are compared with the available historical speed data. Where possible speed data from
the three years prior to the MSMP are included in this table—however, in some cases
data are only available from one or two of the prior years. Also in some cases, speed data
are not available from the whole of the Second Enhanced Enforcement Period or the
whole of the Second Regular Enhancement Period—in these cases the dates from which
the data are available are noted in the table. In the second of the two tables for each
ATR, the focus is on drivers traveling at least 5 mph and at least 10 mph above the new
speed limit adopted for the MSMP—i.e., on drivers traveling at 65 mph or more and at 70
mph or more. In this second table, we present the number (and proportion) of vehicles
traveling above these speeds throughout the Second Enhanced Enforcement Period or the
Second Regular Enhancement Period. We also present the average number of vehicles
traveling above these speeds every day. Then, the table presents the decrease in the
number of vehicles relative to the number that were traveling at these speeds before the
MSMP. It should be noted that, in each of three years before the MSMP was adopted,
these speeds (of 65 mph or more and 70 mph or more) were 10 mph and 15 mph above
the pre-MSMP speed limit.
A3-21
ATR-210—Enhanced Enforcement Period #2
Table 3.1: ATR-210—Speed Data from Enhanced Enforcement Period #2
Compared with Speed Data from Three Previous Years
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
(All Eight
Weeks)
(All Eight
Weeks)
Decrease/
Increase as
Compared
to Three
Years
Earlier
(All Eight
Weeks)
Measure
Test Period
(Six Weeks
Only
12/19/05 to
1/29/06)
Mean (mph)
59.429646
+0.948192
-0.32335**
-1.12135**
Percent in 10 mph pace
63.68294
+12.2559**
+5.1837**
+5.0924**
0.1608169
-0.025459*
-0.055239**
-0.083321**
0.0398542
-0.013929*
-0.020513**
-0.034442**
0.011370
-0.004858*
-0.007350*
-0.014224**
0.002848
-0.001102*
-0.001965*
-0.003586*
0.000869
-0.000578*
-0.000836*
-0.001726*
41,426
53,920
56,305
55,481
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.1 (b): ATR-210—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Six Weeks
Only 12/19/05
to 1/29/06)
7.83616*
60.186365
53.862910
65.447116
67.513870
69.580623
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-22
Table 3.2 (a): ATR-210—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #2 and During the Previous Three
Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared Compared to
Two Years
to One
Earlier
Year
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(Six Weeks
Only
12/19/05 to
1/29/0)
Daily
Average
in Test
Period
6,662
159
-25
-54
-82
1,651
39
-14
-20
-34
41,426
986
—
—
—
Table 3.2 (b): ATR-210—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #2 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.160817
0.160817
-0.025459
-0.055239
-0.083321
0.039854
0.039854
-0.013929
-0.020513
-0.034442
41,426
986
—
—
—
Test Period
(Six Weeks
Only
12/19/05 to
1/29/0)
A3-23
ATR-210—Regular Enforcement Period #2
Table 3.3 (a): ATR-210—Speed Data from Regular Enforcement Period #2, from
1/30/06 to 2/26/06, Compared with Speed Data from Three Previous Years
Measure
Test Period
(1/30/06 to
2/26/06)
Decrease/Incr
ease as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
58.740028
-2.3333**
-2.09345**
-1.9345**
Percent in 10 mph pace
57.559748
-2.3430
-1.9529*
-2.7485*
0.161471
-0.085460**
-0.082046**
-0.077828**
0.040589
-0.036248**
-0.032032**
-0.030332**
0.011966
-0.012107*
-0.011793*
-0.010484*
0.002696
-0.003575*
-0.002968*
-0.002972*
0.000739
-0.001824*
-0.000983*
-0.001396*
27,076
29,660
29,041
27,171
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.3 (b): ATR-210—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to
2/26/06)
8.94601*
59.917411
52.471429
65.474488
67.542621
69.610755
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-24
Table 3.4 (a): ATR-210—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #2 and During the Previous Three Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
4,372
156
-83
-79
-75
1,099
39
-32
-31
-29
27,076
967
—
—
—
Table 3.4 (b): ATR-210—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #2 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.161471
0.161471
-0.085460
-0.082046
-0.077828
0.040589
0.040589
-0.036248
-0.032032
-0.030332
27,076
967
—
—
—
A3-25
ATR-219—Enhanced Enforcement Period #2
Table 3.5 (a): ATR-219—Speed Data from Enhanced Enforcement Period #2, from
12/5/05 to 1/29/06, Compared with Speed Data from Three Previous Years
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Measure
(All Eight
Weeks)
Decrease/
Increase as
Compared to
One Year
Earlier
(Four Weeks
Only 1/2/05 to
1/29/05)
(All Eight
Weeks)
(All Eight
Weeks)
Mean (mph)
61.02608282
+1.543789**
-0.028906**
-0.416851**
Percent in 10 mph pace
79.9426838
+8.7659**
+5.8028**
+13.2861**
0.1043378
ns (-0.000283)
-0.042630**
-0.105599**
0.018891154
-0.002346*
-0.013139**
-0.040111**
0.004722789
ns
-0.002333*
-0.00984**
0.001530835
ns
-0.000391*
-0.001510*
0.000644905
ns
ns
-0.000515*
153,511
75,482
159,722
161,163
Test Period
(12/05/05 to
1/29/06)
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.5 (b): ATR-219—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/05/05 to
1/29/06)
5.23940*
61.6318139
56.76615436
64.61128764
65.25383091
68.1796333
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-26
Table 3.6 (a): ATR-219—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #2 and During the Previous Three
Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared Compared to
Two Years
to One
Earlier
Year
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(12/05/05 to
1/29/06)
Daily
Average
in Test
Period
16,017
286
-1
-117
-289
2,900
52
-6
-36
-110
153,511
2,741
—
—
—
Table 3.6 (b): ATR-219—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #2 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(12/05/05 to
1/29/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.104338
0.104338
-0.000283
-0.042630
-289
0.018891
0.018891
-0.002346
-0.013139
-110
153,511
2,741
—
—
—
A3-27
ATR-219—Regular Enforcement Period #2
Table 3.7 (a): ATR-219—Comparison of Speed Data from Regular Enforcement
Period #2, from 1/30/06 to 2/26/06, Compared with Speed Data from Two and Three
Years Earlier
Measure
Test Period
(1/30/06 to
2/26/06)
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
61.122158
-0.04258**
-0.14316**
Percent in 10 mph pace
77.609425
+2.8980*
+10.2582*8
0.127167
-0.019267*
-0.077970**
0.0230674
-0.006330*
-0.027056**
0.005722
-0.000792*
-0.007056*
0.001594
ns
-0.001059*
0.000514
ns
-0.000374*
77,772
81,368
79,903
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.7 (b): ATR-219—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to
2/26/06)
5.72704*
61.816355
56.815628
64.805024
66.304842
68.706398
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-28
Table 3.8 (a): ATR-219—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #2 and with Two and Three Years
Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test
Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
9,890
353
-54
-217
1,794
64
-18
-75
77,772
2,778
—
—
Table 3.8 (b): ATR-219—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #2 and with Two and Three Years Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.127167
0.127167
-0.019267
-0.077970
0.023067
0.023067
-0.006330
-0.027056
77,772
2,778
—
—
A3-29
ATR-220—Enhanced Enforcement Period #2
Table 3.9: ATR-220—Speed Data from Enhanced Enforcement Period #2, from
12/5/05 to 1/29/06, Compared with Speed Data from One Year Earlier
Measure
Test Period
(12/05/05 to 1/29/06)
Decrease/Increase as
Compared to One Year
Earlier
Mean (mph)
59.6439054
+1.299492**
Percent in 10 mph pace
72.114855
+14.4658**
0.11786828
-0.010430*
0.02717719
-0.006108*
0.00533323
-0.001243*
0.00162487
ns
0.00049794
ns
76,314
76,790
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.9 (b): ATR-220—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/05/05 to 1/29/06)
6.94698*
60.5012187
55.2018775
64.6217179
65.9851178
68.7417281
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-30
Table 3.10 (a): ATR-220—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #2 and One Year Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(12/05/05 to
1/29/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
8,995
161
-14
2,074
37
-8
76,314
1,363
—
Table 3.10 (b): ATR-220—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #2 and One Year Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(12/05/05 to
1/29/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.117868
0.117868
-0.010430
0.027177
0.027177
-0.006108
76,314
1,363
—
A3-31
ATR-220—Regular Enforcement Period #2
Table 3.11 (a): ATR-220—Comparison of Speed Data from Regular Enforcement
Period #2, from 1/30/06 to 2/26/06, with Speed Data from One Year Earlier
Measure
Test Period
(1/30/06 to 2/26/06)
Decrease/Increase as
Compared to One Year
Earlier
Mean (mph)
60.40075
-1.3806
Percent in 10 mph pace
73.4334
+3.3403
0.145253
-0.059490**
0.037641
-0.020836*
0.008682
-0.004825*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.002750
-0.001720*
0.0008628
-0.000524*
Vehicle Total
37,087
41,828
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.11 (b): ATR-220—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to 2/26/06)
6.97581*
61.20785
55.77447
64.94926
67.10261
69.42577
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-32
Table 3.12 (a): ATR-220—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #2 and One Year Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(1/30/06 to
2/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
5,387
192
-79
1,396
50
-28
37,087
1,325
—
Table 3.12 (b): ATR-220—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #2 and One Year Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(1/30/06 to
2/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.145253
0.145253
-0.059490
0.037641
0.037641
-0.020836
37,087
1,325
—
3.2. Speed Data from ATRs located Outside Enhanced Enforcement Zones
There were four ATRs located Outside Enhanced Enforcement Zones on 2-Lane 2-Way
Highways. These ATRs were as follows—(1) ATR-179, on USTH 59, near Garvin, in
Lyon County, (2) ATR-198, on USTH 212, East of TH 23, in Chippewa County, (3)
ATR-199, on USTH 75, North of CR 69, in Pipestone County, and ATR-222, on MNTH
65, near Pliny, in Aitkin County. During the MSMP, at the locations of the ATRs located
Outside Enhanced Enforcement Zones, speed limits remained unchanged—at 55 mph—
and there were no changes in enforcement. For each of these ATRs, the speed data
obtained during 2005, when the MSMP occurred, was compared with the historical speed
data. These comparisons are reported site by site, first for the eight-week time period
between 12/5 and 1/29, when the Second Enhanced Enforcement Period occurred during
the MSMP, and then for the four-week time period between 1/30 and 2/26, when the
Second Regular Enhancement Period occurred during the MSMP.
For each of the four ATRs located Outside Enhanced Enforcement Zones (as for the
ATRs located Within Enhanced Enforcement Zones), two tables are presented for each
time period. In the first table, speed data from the Test Year is compared with the
A3-33
historical speed data. We include speed data from the three years prior to the MSMP in
the table, whenever possible—it should be noted that in some cases data are only
available from one or two prior years. Also in some cases, speed data are not available
from the whole of the eight-week Enhanced Enforcement Period or the four-week
Regular Enhancement Period—in these cases the dates from which the data are available
are noted in the table. In the second of the two tables, for each of the ATRs located
Outside Enhanced Enforcement Zones, the focus is on drivers traveling at least 5 mph
and at least 10 mph above the new speed limit adopted for the MSMP—i.e., drivers
traveling at least 65 mph and at least 70 mph). It should be noted that during the MSMP,
as well as during the three years before it was adopted, these speeds (of at least 65 mph
and at least 70 mph) were 10 mph and 15 mph above the actual speed limit at the
locations of the four ATRs located Outside Enhanced Enforcement Zones. In this second
table, we present the number and proportion of vehicles traveling above these speeds
throughout the Second Enhanced Enforcement Period or the Second Regular
Enhancement Period. We also present the average number of vehicles traveling above
these speeds every day. Then, the table presents the decrease in the number of vehicles
relative to the number that were traveling at these speeds before the Test Year.
A3-34
ATR-179—Enhanced Enforcement Period #2
Table 3.13 (a): ATR-179—Comparison of Speed Data from Enhanced Enforcement
Period #2, from 12/5/05 to 1/29/06, with Speed Data from One Year Earlier
Decrease/Increase as
Compared to One
Year Earlier
Measure
Test Period
(12/05/05 to 1/29/06)
Mean (mph)
53.99268
Percent in 10 mph pace
64.323
-1.05168**
—
-3.0041*
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
0.011081
0.002181
0.000541
0.00027
0.000093197
-0.006724*
-0.001265*
-0.000226*
ns
ns
Vehicle Total
107,300
100,423
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.13 (b): ATR-179—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/05/05 to 1/29/06)
7.40692*
54.88121
49.02082
59.79801
61.42953
63.43724
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph
A3-35
Table 3.14 (a): ATR-179—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #2 and One Year Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(12/05/05 to
1/29/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
1,189
21
-13
234
4
-2
107,300
1,916
—
Table 3.14 (b): ATR-179—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #2 and One Year Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(12/05/05 to
1/29/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.011081
0.011081
-0.006724
0.002181
0.002181
-0.001265
107,300
1,916
—
A3-36
ATR-179—Regular Enforcement Period #2
Table 3.15 (a): ATR-179—Comparison of Speed Data from Regular Enforcement
Period #2, from 1/30/06 to 2/26/06, with Speed Data from One Year Earlier
Measure
Test Period
(1/30/06 to 2/26/06)
Decrease/Increase as
Compared to One Year
Earlier
Mean (mph)
54.34073
-0.93039675**
Percent in 10 mph pace
65.211
-1.763319*
0.011132
-0.006541*
0.00145
-0.001266*
0.000255
-0.000347*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.0000784
-0.000290*
0.0000392
ns
Vehicle Total
51,022
51,545
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.15 (b): ATR-179—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to 2/26/06)
7.36149*
55.40009
49.46964
60.01807
61.81184
63.60561
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-37
Table 3.16 (a): ATR-179—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #2 and One Year Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(1/30/06 to
2/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
568
20
-12
74
3
-2
51,022
1,822
—
Table 3.16 (b): ATR-179—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #2 and One Year Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(1/30/06 to
2/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.011132
0.011132
-0.006541
0.001450
0.001450
-0.001266
51,022
1,822
—
A3-38
ATR-198—Enhanced Enforcement Period #2
Table 3.17 (a): ATR-198—Comparison of Speed Data from Enhanced Enforcement
Period #2, from 12/5/05 to 1/29/06, with Speed Data from One and Three Years
Earlier
Measure
Test Period
(12/05/05 to
1/29/06)
Decrease/Increase
as Compared to
One Year Earlier
Decrease/Increase as
Compared to Three
Years Earlier
Mean (mph)
55.2110979
-2.26175**
-3.48819**
Percent in 10 mph pace
49.343733
-10.634**
-17.453**
0.04946394
-0.013367*
-0.034509**
0.00859446
-0.003953*
-0.008881**
0.00133815
-0.001066*
-0.001965*
0.00043012
-0.000323*
-0.000619*
0.00011948
-0.0001261*
-0.000245*
125,546
118,111
115,358
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.17 (b): ATR-198—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/05/05 to
1/29/06)
11.10283*
57.9280442
49.0102996
63.3433218
64.1672442
64.9911666
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-39
Table 3.18 (a): ATR-198—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #2 and with One and Three Years
Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(12/05/05
to 1/29/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
6,210
111
-30
-77
1,079
19
-9
-20
125,546
2,242
—
—
Table 3.18 (b): ATR-198—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #2 and with One and Three Years Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(12/05/05 to
1/29/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.049464
0.049464
-0.013367
-0.034509
0.008594
0.008594
-0.003953
-0.008881
125,546
2,242
—
—
A3-40
ATR-198—Regular Enforcement Period #2
Table 3.19 (a): ATR-198—Comparison of Speed Data from Regular Enforcement
Period #2, from 1/30/06 to 2/26/06, with Speed Data from Three Previous Years
Measure
Test Period
(1/30/06 to
2/26/06)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
56.14719
-1.97457**
+0.207233**
+0.086754**
Percent in 10 mph pace
53.8178
-10.429**
+5.5593**
+3.2766*
0.049789
-0.01714*
-0.00548*
-0.01297*
0.008050
-0.00443*
-0.00217*
-0.00502*
0.001257
-0.00094*
ns
-0.001*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.000376
-0.00025*
ns
-0.00042*
0.000114
ns
ns
-0.0001947*
Vehicle Total
61,239
59,227
61,027
51,802
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.19 (b): ATR-198—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to
2/26/06)
9.76153
58.18405
50.50084
63.42443
64.21055
64.99668
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-41
Table 3.20 (a): ATR-198—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #2 and During the Previous Three Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
3,047
109
-37
-12
-28
493
18
-10
-5
-11
61,239
2,187
—
—
—
Table 3.20 (b): ATR-198—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #2 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.049789
0.049789
-0.01714
-0.00548
-0.01297
0.008050
0.008050
-0.00443
-0.00217
-0.00502
61,239
2,187
—
—
—
A3-42
ATR-199—Enhanced Enforcement Period #2
Table 3.21 (a): ATR-199—Comparison of Speed Data from Enhanced Enforcement
Period #2, from 12/5/05 to 1/29/06, with Speed Data from Three Previous Years
Measure
Test Period
(12/05/05 to
1/29/06)
Decrease/
Increase as
compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
57.62188
-1.788443**
0.004603**
-0.717624**
Percent in 10 mph pace
64.3925
-10.4712**
-1.4762*
-2.8936*
0.062237
-0.004536*
-0.00996*
-0.025141**
0.016055
-0.002894*
-0.005866*
-0.010962*
0.00386
ns
-0.002859*
-0.004774*
0.001337
ns
-0.000653*
-0.001527*
0.000556
ns
-0.000342*
-0.000810*
66,584
80,586
66,831
68,106
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.21 (b): ATR-199—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/05/05 to
1/29/06)
7.25228*
58.26944
52.44956
63.49648
64.35306
66.32488
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-43
Table 3.22 (a): ATR-199—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #2 and During the Previous Three
Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared Compared to
Two Years
to One
Earlier
Year
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(12/05/05 to
1/29/06)
Daily
Average
in Test
Period
4,144
74
-5
-12
-30
1,069
19
-3
-7
-13
66,584
1,189
—
—
—
Table 3.22 (b): ATR-199—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #2 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(12/05/05 to
1/29/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.062237
0.062237
-0.004536
-0.00996
-0.025141
0.016055
0.016055
-0.002894
-0.005866
-0.010962
66,584
1,189
—
—
—
A3-44
ATR-199—Regular Enforcement Period #2
Table 3.23: ATR-199—Comparison of Speed Data from Regular Enforcement
Period #2, from 1/30/06 to 2/26/06, with Speed Data from Two and Three Years
Earlier
Measure
Test Period
(1/30/06 to 2/26/06)
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
58.5577
1.228273**
0.524339**
Percent in 10 mph pace
69.9446
+4.5700*
+3.9961
0.071854
+0.004025*
-0.01164*
0.019133
-0.002285*
-0.007801*
0.005126
-0.001161*
ns
0.002056
ns
-0.00066
0.000656
ns
-0.00046*
33,554
32,449
32,375
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.23 (b): ATR-199—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to 2/26/06)
6.24904*
58.75376
54.09113
63.77735
64.55964
67.07264
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-45
Table 3.24 (a): ATR-199—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph)
During Regular Enforcement Period #2 with the Speed Data from Two and Three
Years Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test
Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
2,411
86
+5
-14
642
23
-3
-9
33,554
1,198
—
—
Table 3.24 (b): ATR-199—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #2 with the Speed Data from Two and Three Years
Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.071854
0.071854
+0.004025)
-0.011640
0.019133
0.019133
-0.002285
-0.007801
33,554
1,198
—
—
A3-46
ATR-222—Enhanced Enforcement Period #2
Table 3.25 (a): ATR-222—Comparison of Speed Data from Enhanced Enforcement
Period #2, from 12/5/05 to 1/29/06, with Speed Data from Three Previous Years
Measure
Test Period
(12/05/05 to
1/29/06)
Decrease/
Increase as
Compared
to One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
62.61493
+2.3945**
0.901116**
0.441459**
Percent in 10 mph pace
53.1163
-9.9289**
-8.6304**
-8.7153**
0.390676
+0.180692**
+0.132334**
+0.112432**
0.163502
+0.093650**
+0.078035**
+0.070121**
0.065717
+0.045259**
+0.038795**
+0.037878**
0.021606
+0.01629**
+0.014557**
+0.015084*8
0.009641
+0.007435**
+0.00673**
+0.007256*8
64,519
60,757
65,967
67,926
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.25 (b): ATR-222—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/05/05 to
1/29/06)
10.87091
63.3051
56.36803
70.6904
73.24703
76.78154
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-47
Table 3.26 (a): ATR-222—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #2 and During the Previous Three
Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(12/05/05 to
1/29/06)
Daily
Average
in Test
Period
25,206
450
+208
+152
+130
10,549
188
+108
+90
+81
64,519
1,152
—
—
—
Table 3.26 (b): ATR-222—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #2 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(12/05/05 to
1/29/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.390676
0.390676
+0.180692
+0.132334
+0.112432
0.163502
0.163502
+0.093650
+0.078035
+0.070121
64,519
1,152
—
—
—
A3-48
ATR-222—Regular Enforcement Period #2
Table 3.27 (a): ATR-222—Comparison of Speed Data from Regular Enforcement
Period #2, from 1/30/06 to 2/26/06, with Speed Data from Three Previous Years
Measure
Test Period
(1/30/06 to
2/26/06)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
62.85387
+1.396035**
+2.344067**
+0.983665**
Percent in 10 mph
pace
54.3091
-7.50725**
-8.2604**
-6.93400**
0.398819
+0.149532**
+0.178416**
+0.129455**
0.169806
+0.086225**
+0.098928**
+0.080231**
0.065704
+0.040716**
+0.045211**
+0.039317**
0.020414
+0.013817**
+0.01529**
+0.013616**
0.009255
+0.006254*
+0.007264*
+0.006844*
30,470
33,656
30,644
29,863
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.27 (b): ATR-222—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to
2/26/06)
10.82959*
63.47933
56.80882
70.95129
73.35277
76.7337
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-49
Table 3.28 (a): ATR-222—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #2 and During the Previous Three Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared Compared to
Two Years
to One
Earlier
Year
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
12,152
434
+163
+194
+141
5,174
185
+94
+108
+87
30,470
1,088
—
—
—
Table 3.28 (b): ATR-222—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #2 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.39882
0.39882
+0.14953
+0.17842
+0.12945
0.16981
0.16981
+0.08623
+0.09893
+0.08023
30,470
1,088
—
—
—
3.3. Overall Effect of the MSMP on 2-Lane 2-Way Highways
In the MSMP, we obtained speed data from seven ATRs located on 2-Lane 2-Way
Highways—three of these ATRs were located Within Enhanced Enforcement Zones,
while the remaining four were located Outside Enhanced Enforcement Zones. The speed
limit was increased from 55 mph to 60 mph at the locations of the three ATRs Within
Enhanced Enforcement Zones, while the speed limit remained unchanged at 55 mph at
the locations of the four ATRs Outside Enhanced Enforcement Zones.
In order to provide a brief overall summary of the effect of the MSMP, we focused on
drivers traveling at least 10 mph above the new speed limit. Speed data from the three
A3-50
ATRs Within Enhanced Enforcement Zones were combined. Then, we compared the
speed data from the Test Year with data from the previous year, when the speed limit at
the locations of the three ATRs was still 55 mph. Table 3.29 shows the results of this
comparison for the Second Enhanced Enforcement Period.
Table 3.29: Effect of MSMP on 2-Lane 2-Way Highways During the Second
Enhanced Enforcement Period at Three ATRs Within Enhanced Enforcement Zones
Sample Total
281,674*
Sample Total
285,062**
One Year Before MSMP
# Over 70 mph
8,662*
Second Enhanced Enforcement Period
# Over 70 mph
7,175**
% Over 70 mph
3.08*
% Over 70 mph
2.52**
Result: 18.18% Decrease in Drivers Traveling Over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-219 during the time period
**Numbers adjusted to account for limited availability of data from ATR-210 during the time period
Table 3.29 indicates that, for the three ATRs Within Enhanced Enforcement Zones on 2Lane 2-Way Highways, during the Second Enhanced Enforcement Period, there was a
18.18% decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the
new speed limit.
A similar comparison was conducted for the Second Regular Enforcement Period. The
results of this comparison are shown in Table 3.30.
Table 3.30: Effect of MSMP on 2-Lane 2-Way Highways During the Second
Regular Enforcement Period at Enforcement Period at Three ATRs Within
Enhanced Enforcement Zones
Sample Total
152,856*
Sample Total
141,937
Pre-MSMP
# Over 70 mph
7,117*
Second Regular Enforcement Period
# Over 70 mph
4,289
% Over 70 mph
4.66*
% Over 70 mph
3.02
Result: 35.19% Decrease in Drivers Traveling Over 70 mph
*Data for ATR-210 and ATR-220 are from one year earlier; data from ATR-219 are from two years earlier.
Table 3.30 shows that, for two ATRs Within Enhanced Enforcement Zones on 2-Lane 2Way Highways, during the Second Regular Enforcement Period, there was a 35.19%
reduction in the number of drivers traveling over 70 mph—i.e., 10 mph over the speed
limit.
A3-51
We also examined the difference between the speed data obtained during the Test Periods
from the four ATRs Outside Enhanced Enforcement Zones, where there was no change
in the level of enforcement during the MSMP and no change in the speed limit. Again in
these comparisons, we focused on drivers traveling at 70 mph or more—while this is 10
mph above the new speed limit Within Enhanced Enforcement Zones, it is 15 mph above
the actual speed limit at the locations of the four ATRs Outside Enhanced Enforcement
Zones. The results of this comparison for speed data obtained during the Second
Enhanced Enforcement Period are shown in Table 3.31.
Table 3.31: Effect of MSMP on 2-Lane 2-Way Highways during the Second
Enhanced Enforcement Period at Four ATRs Outside Enhanced Enforcement Zones
Sample Total
359,877
Sample Total
363,949
One Year Before MSMP
# Over 70 mph
7,598
Second Enhanced Enforcement Period
# Over 70 mph
12,931
% Over 70 mph
2.11
% Over 70 mph
3.55
Result: 68.25% Increase in Drivers Traveling Over 70 mph
Table 3.31 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on 2-Lane 2-Way Highways, during the Second Enhanced Enforcement Period, there was
a 68.25% increase in the number of drivers traveling over 70 mph—i.e., 10 mph above
the new speed limit Within Enhanced Enforcement Zones (and 15 mph above the current
speed limit Outside the Enhanced Enforcement Zones).
A similar comparison was conducted for the Second Regular Enforcement Period. The
results of this comparison using speed data from the four ATRs located Outside
Enhanced Enforcement Zones are shown in Table 3.32.
Table 3.32: Effect of MSMP on 2-Lane 2-Way Highways during Second Regular
Enforcement Period at Four ATRs Outside Enhanced Enforcement Zones
Sample Total
176,877*
Sample Total
176,285
One Year Before MSMP
# Over 70 mph
4,555*
Second Regular Enforcement Period
# Over 70 mph
6,383
% Over 70 mph
2.58*
% Over 70 mph
3.62
Result—40.31% Increase in Drivers Traveling over 70 mph
*Data for ATR-179, ATR-198, and ATR-222 are from one year earlier; data from ATR-199 are from two
years earlier.
A3-52
Table 3.32 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on the 2-Lane 2-Way Highways, during the Second Regular Enforcement Period there
was a 40.31% increase in the number of drivers traveling over 70 mph—i.e., at 10 mph
over the new speed limit Within Enhanced Enforcement Zones (and 15 mph above the
current speed limit Outside Enhanced Enforcement Zones).
Comparisons between speed data from the ATRs located Within Enhanced Enforcement
Zones and the ATRs located Outside Enhanced Enforcement Zones should be treated
with caution. In particular, it should be noted that the three ATRs located Within
Enhanced Enforcement Zones are all in Northern Minnesota, and that the proportion of
vehicles traveling at 70 mph or more ranges between 0.012 and 0.039 for these ATRs. In
contrast, the four ATRs located Outside Enhanced Enforcement Zones are more widely
spread throughout the state—with three ATRs in South Western Minnesota and one in
East Central Minnesota. For these four ATRs, the there is a much greater range in the
proportion of vehicles traveling at 70 mph or more—the proportion varies between
0.0015, for ATR-179—one of the three ATRs in South Western Minnesota—and 0.170
for ATR-222—which is located in East Central Minnesota.
A3-53
Section 4. Speed Data Obtained on 4-Lane Divided Highways
We obtained speed data from five ATRs located on 4-Lane Divided Highways. Four of
these ATRs were located Within Enhanced Enforcement Zones, while the remaining ATR
was located Outside the Enhanced Enforcement Zones. At the locations of the four
ATRs Within the Enhanced Enforcement Zones and the ATRs Outside the Enhanced
Enforcement Zones, the speed limit was unchanged—remaining at 65mph—during the
MSMP.
For the ATRs located Within Enhanced Enforcement Zones and the ATR located Outside
Enhanced Enforcement Zones on 4-Lane Divided Highways, we present comparisons of
the speed data obtained during the Test Year with the speed data obtained at those same
ATRs in the three years prior to the MSMP. Comparisons using the speed data from the
ATRs located Within Enhanced Enforcement Zones are presented first. Then, we present
comparisons using the speed data from the ATR located Outside the Enhanced
Enforcement Zones.
In making the comparisons between the speed data obtained during the Test Year and the
speed data obtained prior to the MSMP, we used two statistical tests. The first test was
used to examine differences in the mean speeds—for this we used the procedure for
comparing population means outlined by Kitchens (1987, p 369-373). The second test
was used to explore differences in the percentage of vehicles in the 10 mph pace and in
the differences in the proportions of vehicle traveling at various speeds. For this test, we
treated the distribution of speeds as a Bernoulli population—i.e., a population in which
each element is one of two possibilities, in this case, (1) in or out of the 10 mph pace, or
(2) above or below a selected speed (e.g., 75 mph). We then used the procedure for
comparing population proportions described by Kitchens (1987, pages 400-404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
ATR in the time periods under consideration. Second, the tests were conducted using an
extremely conservative correction, with n-values equal to the number of hours in each
test period—the rationale for this was that it is possible, when traffic is congested, that
individual vehicles may travel at speeds which are not independent of each other.
4.1. Speed Data from the ATRs located Within Enhanced Enforcement Zones
The four ATRs located Within Enhanced Enforcement Zones on 4-Lane Divided
Highways were as follows; (1) ATR-172, on US-10, near Dilworth, in Clay County, (2)
ATR-187, on US-10, near Rice, in Benton County, (3) ATR-188, on US-52, North of
Rochester, in Olmstead County, and (4) ATR-197, on SR-60, West of SR-4, in
Watonwan County. At these four sites, the speed limit remained unchanged at 65 mph.
The effect of the MSMP on the speed data at each of these four ATRs is reported in this
section. It is reported ATR by ATR—with the effect of the MSMP in the Second
A3-54
Enhanced Enforcement Period, between 12/5/05 and 1/29/06, followed by its effect in the
Second Regular Enhancement Period, between 1/30/06 and 2/26/06.
For each of the four ATRs Within Enhanced Enforcement Zones, two tables are presented
for each time period. In the first of these tables, speed data from the Test Year are
compared with the available historical speed data. Where possible speed data from the
three years prior to the MSMP are included in this table—however, in some cases data
are only available from one or two of the prior years. Also in some cases, speed data are
not available from the whole of the Second Enhanced Enforcement Period or the Second
Regular Enhancement Period—in these cases the dates from which the data are available
are noted in the table. In the second of the two tables for each ATR the focus is on
drivers traveling at least 5 mph and at least 10 mph above the speed limit adopted for the
MSMP—i.e., on drivers traveling at 70 mph or more and at 75 mph or more. In this
second table, we present the number (and proportion) of vehicles traveling above these
speeds throughout the Second Enhanced Enforcement Period or the Second Regular
Enhancement Period. We also present the average number of vehicles traveling above
these speeds every day. Then, the table presents the decrease in the number of vehicles
relative to the number that were traveling at these speeds before the MSMP.
A3-55
ATR-172—Enhanced Enforcement Period #2
Table 4.1 (a): ATR-172—Comparison of Speed Data from Enhanced Enforcement
Period #2, from 12/5/05 to 1/29/06, and Data from One Year Earlier
Measure
Test Period
(12/5/05 to 1/29/06)
Decrease/
Increase
Compared to
One Year Earlier
Mean (mph)
63.55037
-0.42479
Percent in 10 mph pace
60.3554
ns (+0.0495)
0.473654
-0.04505**
0.117253
-0.02967**
0.009870
-0.00348*
0.001812
-0.00077*
0.000523
-0.00041*
715,109
682,782
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.1 (b): ATR-172—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/5/05 to 1/29/06)
7.32734*
64.58044
57.5234
69.54059
70.80336
73.13146
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-56
Table 4.2 (a): ATR-172—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Enhanced Enforcement Period #2 and One Year Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Test Period
(12/5/05 to
1/29/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
83,849
1,497
-379
7,057
126
-44
715,109
12,769
—
Table 4.2 (b): ATR-172—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Enhanced Enforcement Period #2 and One Year Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(12/5/05 to
1/29/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.117253
0.117253
-0.02967
0.009870
0.009870
-0.00348
715,109
12,769
—
A3-57
ATR-172—Regular Enforcement Period #2
Table 4.3 (a): ATR-172—Comparison of Speed Data from Regular Enforcement
Period #2, from 1/30/06 to 2/26/06, and Speed Data from One Year Earlier
Measure
Test Period
(1/30/06 to 2/26/06)
Decrease/Increase
Compared to One
Year Earlier
Mean (mph)
63.04163
-2.86595**
Percent in 10 mph pace
55.5904
-13.548**
0.457525
-0.17979**
0.113611
-0.08125**
0.008827
-0.00829*
0.00162
-0.00119*
0.000469
-0.00023*
345,662
363,866
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.3 (b): ATR-172—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to 2/26/06)
7.69128*
64.27828
56.33149
69.47096
70.64948
73.03533
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-58
Table 4.4 (a): ATR-172—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Regular Enforcement Period #2 and One Year Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Test Period
(1/30/06 to
2/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
39,271
1,403
-1,003
3,051
109
-102
345,662
12,345
—
Table 4.4 (b): ATR-172—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Regular Enforcement Period #2 and One Year Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(1/30/06 to
2/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.113611
0.113611
-0.08125
0.008827
0.008827
-0.00829
345,662
12,345
—
A3-59
ATR-187—Enhanced Enforcement Period #2
Table 4.5 (a): ATR-187—Comparison of Speed Data from Enhanced Enforcement
Period #2, from 12/5/05 to 1/29/06, and Speed Data from Two Previous Years
Measure
(All Eight
Weeks)
Decrease/
Increase
Compared to
One Year
Earlier
(Four Weeks
Only)
(12/5/04 to
1/1/05)
Mean (mph)
67.306226
-1.76778**
-3.51061**
Percent in 10 mph pace
60.03901
-9.027**
-4.925**
0.7068451
-0.11555**
-0.16345**
0.343050
-0.11812**
-0.25157**
0.0756832
-0.01175*
-0.12702**
Test Period
(12/5/05 to
1/29/06)
Decrease/
Increase
Compared to
Two Years
Earlier
(All Eight
Weeks)
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.0143711
-0.00099*
-0.02256**
0.0036845
+0.001496*
-0.00068*
Vehicle Total
948,850
479,315
925,059
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.5 (b): ATR-187—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/5/05 to
1/29/06)
7.56543*
67.842879
61.595608
73.610209
74.545254
77.094463
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-60
Table 4.6 (a): ATR-187—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Enhanced Enforcement Period #2 and with One and Two Years
Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test
Period
(12/05/05
to 1/29/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
325,503
5,813
-2,001
-4,263
71,812
1,282
-199
-2,152
948,850
16,944
—
—
Table 4.6 (b): ATR-187—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Enhanced Enforcement Period #2 and with One and Two Years Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test Period
(12/05/05 to
1/29/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.343050
0.343050
-0.11812
-0.25157
0.075683
0.075683
-0.01175
-0.12702
948,850
16,944
—
—
A3-61
ATR-187—Regular Enforcement Period #2
Table 4.7 (a): ATR-187—Comparison of Speed Data from Regular Enforcement
Period #2, from 1/30/06 to 2/26/06, and Speed Data from Three Years Earlier
Measure
Test Period
(1/30/06 to
2/26/06)
Decrease/Increase
Compared to
Three Years Earlier
Mean (mph)
67.72763
-0.97027**
Percent in 10 mph pace
62.0159
-2.731*
0.735112
-0.04985**
0.360456
-0.04390*
0.078599
-0.02298*
0.013925
-0.00938*
0.003133
-0.00052*
458,960
425,936
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.7 (b): ATR-187—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to
2/26/06)
7.21148*
68.13771
62.15437
73.73339
74.62036
77.21103
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-62
Table 4.8 (a): ATR-187—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Regular Enforcement Period #2 and One Year Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Test Period
(1/30/06 to
2/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
165,435
5,908
-720
36,074
1,288
-377
458,960
16,391
—
Table 4.8 (b): ATR-187—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Regular Enforcement Period #2 and One Year Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(1/30/06 to
2/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.360456
0.360456
-0.04390
0.078599
0.078599
-0.02298
458,960
16,391
—
A3-63
ATR-188—Enhanced Enforcement Period #2
Table 4.9 (a): ATR-188—Comparison of Speed Data from Enhanced Enforcement
Period #2, from 12/5/05 to 1/29/06, and Speed Data from One and Three Years
Earlier
Test Period
(12/5/05 to 1/29/06)
Decrease/
Increase
Compared to
One Year Earlier
Measure
(All Eight Weeks)
(All Eight Weeks)
Decrease/Increase
Compared to
Three Years
Earlier
(Four Weeks Only)
(12/5/02 to 1/1/03)
Mean (mph)
66.47685
+0.337006**
+0.076897**
Percent in 10 mph pace
59.1486
+2.23825
+13.1124**
0.648860
+0.002861*
+0.033934*
0.293863
-0.004521*
-0.066294**
0.064954
-0.006123*
-0.060995**
0.006909
-0.001637*
-0.030228**
0.00158
-0.000252*
-0.012001**
1,515,355
1,457,212
758,292
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.9 (b): ATR-188—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/5/05 to 1/29/06)
7.40146*
67.09664
60.80374
73.14236
74.2345
76.28813
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-64
Table 4.10 (a): ATR-188—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Enhanced Enforcement Period #2 and with One and Three Years
Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(12/05/05
to 1/29/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
445,307
7,952
-122
-1,734
98,428
1,758
-166
-1,651
1,515,355
27,060
—
—
Table 4.10 (b): ATR-188—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Enhanced Enforcement Period #2 and with One and Three Years Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(12/05/05 to
1/29/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.293863
0.293863
-0.004521
-0.066294
0.064954
0.064954
-0.006123
-0.060995
1,515,355
27,060
—
—
A3-65
ATR-188—Regular Enforcement Period #2
Table 4.11 (a): ATR-188—Comparison of Speed Data from Regular Enforcement
Period #2, from 1/30/06 to 2/26/06, and Speed Data from One and Three Years
Earlier
Measure
Test Period
(1/30/06 to 2/26/06)
Decrease/Increase
Compared to
One Year Earlier
Decrease/Increase
Compared to
Three Years Earlier
Mean (mph)
67.08569
+0.085876**
+1.382396**
Percent in 10 mph pace
59.9874
+2.6017*
+12.4295**
0.694238
+0.002019*
+0.11411**
0.323300
-0.02186*
+0.009863*
0.073424
-0.01374*
-0.03540**
0.007739
-0.00237*
-0.02303**
0.00173
-0.0003775*
-0.00882**
750,998
748,849
733,945
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.11 (b): ATR-188—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to 2/26/06)
7.15943*
67.6182
61.35986
73.46772
74.46821
76.78304
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-66
Table 4.12 (a): ATR-188—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Regular Enforcement Period #2 and with One and Three Years
Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
242,798
8,671
-586
+264
55,141
1,969
-369
-949
750,998
26,821
—
—
Table 4.12 (b): ATR-188—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Regular Enforcement Period #2 and with One and Three Years Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.32330
0.32330
-0.02186
+0.00986
0.073424
0.073424
-0.01374
-0.03540
750,998
26,821
—
—
A3-67
ATR-197—Enhanced Enforcement Period #2
Table 4.13 (a): ATR-197—Comparison of Speed Data from Enhanced Enforcement
Period #2 and Speed Data from the Three Years Earlier
Measure
Test Period
(Two Weeks
(12/5/05 to
12/18/05)
Decrease/Increase
Compared to
Three Years
Earlier
(All Eight Weeks)
Mean (mph)
63.815249
-1.45759**
Percent in 10 mph pace
63.63825
-1.62109*
0.4780119
-0.10048**
0.1258573
-0.08211**
0.0117385
-0.01472*
0.0023823
-0.00439*
0.000634
-0.001568*
52,051
228,851
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.13 (b): ATR-197—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Two Weeks
(12/5/05 to
12/18/05)
7.42755*
64.678204
58.618725
69.657215
71.132912
73.323611
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-68
Table 4.14 (a): ATR-197—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Enhanced Enforcement Period #2 and Three Years Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Test Period
(Two Weeks
12/5/05 to
12/18/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Three Years
Earlier
6,551
468
-305
611
44
-58
52,051
3,718
—
Table 4.14 (b): ATR-197—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Enhanced Enforcement Period #2 and Three Years Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(Two Weeks
12/5/05 to
12/18/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Three Years
Earlier
0.125857
0.125857
-0.08211
0.011739
0.011739
-0.01472
52,051
3,718
—
A3-69
ATR-197—Regular Enforcement Period #2
Table 4.15 (a): ATR-197—Comparison of Speed Data from Regular Enforcement
Period #2 and Speed Data from Two and Three Years Earlier
(All Four Weeks)
Decrease/Increase
Compared to
Three Years
Earlier
(All Four Weeks)
64.71882
+1.7296**
+0.33576**
72.86727
+20.469**
+10.373**
0.5398375
+0.06576**
+0.02695*
0.1172464
-0.04260**
-0.04151**
0.0125535
-0.00606*
-0.00592*
0.0031065
-0.00119*
-0.0009819*
0.0008276
-0.0005544*
-0.0005220*
78,544
102,029
100,771
Test Period
Measure
(Three Weeks
2/6/06 to
2/26/06)
Mean (mph)
Percent in 10 mph
pace
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
Decrease/Increase
Compared to
Two Years Earlier
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.15 (b): ATR-197—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Three Weeks
2/6/06 to
2/26/06)
6.22138*
65.471349
60.221193
69.612467
70.823665
73.211602
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-70
Table 4.16 (a): ATR-197—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Regular Enforcement Period #2 and with One and Three Years
Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
9,209
439
-159
-155
986
47
-22
-22
78,544
3,740
—
—
Test
Period
(Three
Weeks
2/6/06 to
2/26/06)
Table 4.16 (b): ATR-197—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Regular Enforcement Period #2 and with One and Three Years Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.11725
0.11725
-0.04260
-0.04151
0.012554
0.012554
-0.00606
-0.00592
78,544
3,740
—
—
Test Period
(Three
Weeks
2/6/06 to
2/26/06)
A3-71
4.2. Speed Data from One ATR located Outside Enhanced Enforcement Zones
There was one ATR located on a 4-Lane Divide Highway Outside the Enhanced
Enforcement Zones. It was ATR-353, on MNTH-169 near Jordan in Scott County.
There were no changes in enforcement at this location. For this ATR, the speed data
obtained during 2005, when the MSMP occurred, was compared with historical speed
data. Comparisons are presented for the eight-week period between 12/5 and 1/29, when
the Second Enhanced Enforcement Period occurred during the MSMP, and then for the
four-week time period between 1/30 and 2/26, when the Second Regular Enhancement
Period occurred.
Two tables are presented for each of these time periods. In the first table, speed data
from the Test Year is compared with historical speed data. Speed data was only available
for the two years prior to the MSMP for ATR-353. In the second of the two tables for
each ATR, the focus is on drivers who were traveling at least 5 mph and at least 10 mph
above the speed limit—i.e., drivers traveling at 70 mph or more and at 75 mph or more.
In this second table, we present the number (and proportion) of vehicles traveling above
these speeds throughout the Second Enhanced Enforcement Period or the Second
Regular Enhancement Period. We also present the average number of vehicles traveling
above these speeds every day. Then, the table presents the decrease in the number of
vehicles relative to the number that were traveling at these speeds in the two years prior
to the implementation of the MSMP.
A3-72
ATR-353—Enhanced Enforcement Period #2
Table 4.17: ATR-353—Comparison of Speed Data from Enhanced Enforcement
Period #2, from 12/5/05 to 1/29/06, and Speed Data from the Two Prior Years
Measure
Test Period
(12/5/05 to 1/29/06)
Decrease/Increase
Compared to
One Year Earlier
Decrease/Increase
Compared to
Two Years Earlier
Mean (mph)
67.27948
-0.409363**
-0.166786**
Percent in 10 mph pace
65.143
ns
+0.00532*
0.736290
-0.023188*
-0.011061*
0.322812
-0.04076**
-0.020933*
0.032083
-0.009343*
-0.005000*
0.004149
-0.001121*
-0.000511*
0.000583
-0.000234*
-0.000151*
1,110,074
1,091,536
1,066,517
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.17 (b): ATR-353—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/5/05 to 1/29/06)
6.28265*
67.85734
62.06524
72.97204
73.83195
74.69185
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-73
Table 4.18 (a): ATR-353—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Enhanced Enforcement Period #2 and with the Two Previous Years
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test
Period
(12/5/05 to
1/29/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
358,345
6,399
-808
-415
35,614
636
-185
-99
1,110,074
19,823
—
—
Table 4.18 (b): ATR-353—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Enhanced Enforcement Period #2 and with the Two Previous Years
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test Period
(12/5/05 to
1/29/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Years
Earlier
0.322812
0.322812
-0.04076
-0.020933
0.032083
0.032083
-0.009343
-0.005000
1,110,074
19,823
—
—
A3-74
ATR-353—Regular Enforcement Period #2
Table 4.19 (a): ATR-353—Comparison of Speed Data from Regular Enforcement
Period #2, from 1/30/06 to 2/26/06, and Speed Data from One and Two Years
Earlier
Measure
Test Period
(1/30/06 to 2/26/06)
Decrease/Increase
Compared to
One Year Earlier
Decrease/Increase
Compared to
Two Years Earlier
Mean (mph)
67.51736
-0.67103**
+0.600635**
Percent in 10 mph pace
66.8639
-0.8056*
+5.6265**
0.754902
-0.040058*
+0.039605*
0.327732
-0.069898**
-0.0020408*
0.030978
-0.017311*
-0.005817*
0.004141
-0.001933*
-0.0005206*
0.000643
-0.000301*
ns
558,752
565,973
519,524
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.17 (b): ATR-353—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to 2/26/06)
5.93525*
67.98361
62.43549
72.9946
73.83705
74.6795
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-75
Table 4.20 (a): ATR-353—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Regular Enforcement Period #2 and with the Two Previous Years
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test
Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
183,121
6,540
-1,395
-41
17,309
618
-345
-116
558,752
19,955
—
—
Table 4.20 (b): ATR-353—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 65 mph) During
Regular Enforcement Period #2 and with the Two Previous Years
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.327732
0.327732
-0.069898)
-0.002041
0.030978
0.030978
-0.017311
-0.005817
558,752
19,955
—
—
3.3. Overall Effect of the MSMP on 4-Lane Divided Highways
In the MSMP, we obtained speed data from five ATRs located on 4-Lane Divided
Highways. Four of these ATRs were located Within Enhanced Enforcement Zones, while
the remaining ATR was located Outside the Enhanced Enforcement Zones. At the
locations of the four ATRs Within the Enhanced Enforcement Zones and the ATRs
Outside the Enhanced Enforcement Zones, the speed limit was unchanged—at 65mph—
during the MSMP.
In order to provide a brief overall summary of the effect of the MSMP, we focused on
drivers traveling at least 10 mph above the speed limit—i.e., drivers traveling at 75 mph
A3-76
or more. Speed data from the four ATRs Within Enhanced Enforcement Zones were
combined. Then, we compared speed data from the Test Year with data from previous
years—in the case of ATR-172, ATR-187, and ATR-188 the data are from one year
earlier, while the data for ATR-197 are from three years earlier. Table 4.21 shows the
results of this comparison for the Second Enhanced Enforcement Period.
Table 4.21: Effect of MSMP on 4-Lane Divided Highways during the Second
Enhanced Enforcement Period at Four ATRs Within Enhanced Enforcement Zones
Sample Total
3,327,475*
Sample Total
3,387,518**
Pre-MSMP
# Over 75 mph
202563*
Second Enhanced Enforcement Period
# Over 75 mph
179,741**
% Over 75 mph
6.09*
% Over 75 mph
5.31**
Result: 12.81% Decrease in Drivers Traveling Over 75 mph
*Numbers adjusted to account for limited availability of data from ATR-188. Also, data for ATR-172,
ATR-187, and ATR-188 are from one year earlier; data for ATR-197 are from three years earlier.
**Numbers adjusted to account for limited availability of data from ATR-187.
Table 4.21 indicates that, for the four ATRs located Within Enhanced Enforcement Zones
on 4-Way Divided Highways, during the Second Enhanced Enforcement Period, there
was a 12.81% decrease in the number of drivers traveling over 75 mph—i.e., 10 mph
over the speed limit.
A similar comparison was conducted for the Second Regular Enforcement Period. In this
case, the data for ATR-172 and ATR-188 are from one year earlier, the data for ATR-187
are from two years earlier, and data for ATR-187 are from three years earlier. The results
of the comparison are shown in Table 4.22.
Table 4.22: Effect of MSMP on 4-Lane Divided Highways during Second Regular
Enforcement Period at Four ATRs Within Enhanced Enforcement Zones
Sample Total
1,640,680*
Sample Total
1,660,345**
Pre-MSMP
# Over 75 mph
116,668*
Second Regular Enforcement Period
# Over 75 mph
95,581**
% Over 75 mph
7.11*
% Over 75 mph
5.75**
Result—19.13% Decrease in Drivers Traveling Over 75 mph
* Data for ATR-172 and ATR-188 are from one year earlier; data for ATR-187 is from two years earlier;
and data for ATR-187 are from three years earlier.
**Numbers adjusted because, for ATR-197, comparison data were from a 2-week time period.
A3-77
Table 4.22 shows that, for the ATRs Within Enhanced Enforcement Zones on 4-Way
Divided Highways, during the Second Regular Enforcement Period there was a 19.13%
reduction in the number of drivers traveling over 75 mph—i.e., 10 mph or more above
the speed limit.
We also examined the difference between the speed data obtained during the Test Periods
from the single ATR Outside the Enhanced Enforcement Zones. For comparison
purposes, we again focused on drivers traveling at 75 mph or more—10 mph above the
speed limit. The results of this comparison for speed data obtained during the Second
Enhanced Enforcement Period are shown in Table 4.23.
Table 2.24: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on a 4-Way Divided Highway During the Second Enhanced Enforcement Period
Sample Total
1,091,536
Sample Total
1,110,074
One Year Before MSMP
# Over 75 mph
45,218
Second Enhanced Enforcement Period
# Over 75 mph
35,614
% Over 75 mph
4.14
% Over 75 mph
3.21
Result: 22.46% Decrease in Drivers Traveling Over 75 mph
Table 4.24 shows that, for the single ATR located Outside the Enhanced Enforcement
Zones on a 4-Way Divided Highway, during the Second Enhanced Enforcement Period,
there was a 22.48% decrease in the number of drivers traveling over 75 mph—i.e., 10
mph or more above the speed limit.
A similar comparison was conducted for the Second Regular Enforcement Period. The
results of this comparison are shown in Table 4.25.
Table 4.26: Effect of MSMP at one ATR Outside the Enhanced Enforcement Zones
on a 4-Way Divided Highway During the Second Regular Enforcement Period
Sample Total
565,973
Sample Total
558,792
One Year Before MSMP
# Over 75 mph
27,330
Second Regular Enforcement Period
# Over 75 mph
17,309
% Over 75 mph
4.83
% Over 75 mph
3.10
Result—35.82% Decrease in Drivers Traveling over 75 mph
A3-78
Table 4.26 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
a 4-Way Divided Highway, during the Second Regular Enforcement Period there was a
35.82% decrease in the number of drivers traveling over 75 mph—i.e., at 10 mph over
the speed limit.
Comparisons between speed data from the ATRs located Within Enhanced Enforcement
Zones and the ATR located Outside the Enhanced Enforcement Zones should be treated
with caution. The four ATRs located Within Enhanced Enforcement Zones are scattered
throughout Minnesota; while the single ATR Outside the Enhanced Enforcement Zones
is located a few miles to the South-West of the Twin Cities—many of the drivers
traveling past this ATR may have traveled through Enhanced Enforcement Zones in the
Cities.
A3-79
Section 5. Speed Data Obtained on Rural Freeways
We obtained speed data from five ATRs located on Rural Freeways. Four of these ATRs
were located Within Enhanced Enforcement Zones, while the remaining ATR was located
Outside the Enhanced Enforcement Zones. At all five ATR locations, the speed limit was
unchanged—at 70 mph—during the MSMP.
In this section of the report, for the ATRs located Within Enhanced Enforcement Zones
and the single ATR located Outside the Enhanced Enforcement Zones, we present
comparisons of the speed data obtained during the Test Year with speed data obtained at
those same ATRs prior to the MSMP. Comparisons using the speed data from the ATRs
located Within Enhanced Enforcement Zones are presented first. Then, we present
comparisons using the speed data from the ATR located Outside the Enhanced
Enforcement Zones.
In making the comparisons between the speed data obtained during the Test Year and the
speed data obtained prior to the MSMP, we used two statistical tests. The first test was
used to examine differences in the mean speeds—for this we used the procedure for
comparing population means outlined by Kitchens (1987, p 369-373). The second test
was used to explore differences in the percentage of vehicles in the 10 mph pace and in
the differences in the proportions of vehicle traveling at various speeds. For this test, we
treated the distribution of speeds as a Bernoulli population—i.e., a population in which
each element is one of two possibilities, in this case, (1) in or out of the 10 mph pace, or
(2) above or below a selected speed (e.g., 75 mph). We then used the procedure for
comparing population proportions described by Kitchens (1987, pages 400-404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
ATR in the time periods under consideration. Second, the tests were conducted using an
extremely conservative correction, using n-values equal to the number of hours in each
test period—the rationale for this was that it is possible, when traffic is congested, that
individual vehicles may travel at speeds which are not independent of each other.
5.1. Speed Data from ATRs located Within Enhanced Enforcement Zones
The four ATRs located Within Enhanced Enforcement Zones on Rural Freeways were as
follows: (1) ATR-175, on I-94, near Saulk Centre in Stearns County, (2) ATR-191, on I35, near Wyoming, in Chisago County, (3) ATR-208, on I-35, near Owatanna in Steele
County, and (4) ATR-227, on I-90, near Alden in Freeborn County. During the MSMP,
there was no change in the speed limit—it remained at 70 mph—at the locations of these
four ATRs.
Unfortunately, throughout both the Second Enhanced Enforcement Period and the
Second Regular Enforcement Period, there were problems with the speed data collected
A3-80
at ATR-191 and ATR-208. Because these data were unreliable, we were unable to make
meaningful comparisons with the historical speed data. The effect of the MSMP on the
speed data at the remaining two ATRs (175 and 227) is reported in this section. It is
reported ATR by ATR—with the effect of the MSMP in the Second Enhanced
Enforcement Period, between 12/5/05 and 1/29/06, followed by its effect in the Second
Regular Enhancement Period, between 1/30/06 and 2/26/06.
For both ATRs, two tables are presented for each time period. In the first of these tables,
speed data from the Test Year are compared with the available historical speed data.
Where possible speed data from the three years prior to the MSMP are included in this
table—however, in some cases data are only available from one or two of the prior years.
Also in some cases, speed data are not available from the whole of the Second Enhanced
Enforcement Period or the Regular Enhancement Period—in these cases the dates from
which the data are available are noted in the table. In the second of the two tables for
each ATRs, the focus is on drivers traveling at least 5 mph and at least 10 mph above the
speed limit—i.e., on drivers traveling at 75 mph or more and at 80 mph or more. In this
second table, we present the number (and proportion) of vehicles traveling above these
speeds throughout the Second Enhanced Enforcement Period or the Second Regular
Enhancement Period. We also present the average number of vehicles traveling above
these speeds every day. Then, the table presents the decrease in the number of vehicles
relative to the number that were traveling at these speeds before the MSMP.
A3-81
ATR-175—Enhanced Enforcement Period #2
Table 5.1 (a): ATR-175—Comparison of Speed Data from Enhanced Enforcement
Period #2 with Speed Data from the Three Previous Years
Decrease/Increase Decrease/Increase
Compared To
Compared To
Decrease/Increase
Three Years
Two Years
Compared To
Earlier
Earlier
One Year Earlier
Measure
Test Period
(Six Weeks)
(12/5/05 to
1/15/06)
Mean (mph)
70.76627899
-1.38077**
-1.87456**
-0.30886**
Percent in 10
mph pace
65.0105632
+5.4023**
+3.0252*
+13.5903**
0.861389684
-0.02226*
-0.04269**
+0.052614**
0.644802621
-0.0642**
-0.09882**
+0.069103**
0.205246636
-0.11886**
-0.14035**
-0.07868**
0.028053946
-0.03632**
-0.0409**
-0.07232**
0.003073525
-0.00432*
-0.00498*
-0.02559**
762,317
964,438
982,973
986,156
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.1 (b): ATR-175—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Six Weeks)
(12/5/05 to
1/15/06)
6.48532*
71.64714651
65.26293547
76.55894231
77.96983572
79.38072914
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-82
Table 5.2 (a): ATR-175—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Enhanced Enforcement Period #2 and During the Previous Three Years
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(Six
Weeks
12/5/05 to
1/15/06)
Daily
Average
in Test
Period
156,463
3,725
-2,157
-2,547
-1,428
21,386
509
-659
-742
-1,313
762,317
18,150
—
—
—
Table 5.2 (b): ATR-175—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Enhanced Enforcement Period #2 and During the Previous Three Years
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.205247
0.205247
-0.11886
-0.14035
-0.07868
0.028054
0.028054
-0.03632
-0.0409
-0.07232
762,317
18,150
—
—
—
Test Period
(Six
Weeks
12/5/05 to
1/15/06)
A3-83
ATR-175—Regular Enforcement Period #2
Table 5.3 (a): ATR-175—Comparison of Speed Data from Regular Enforcement
Period #2 with Speed Data from the Three Previous Years
Decrease/Increase Decrease/Increase
Compared to
Compared to
Decrease/Increase
Three Years
Two Years
Compared To
Earlier
Earlier
One Year Earlier
Measure
Test Period
(Two Weeks
2/13/06 to
2/26/06)
Mean (mph)
71.783832
-1.19038**
+0.292867**
+1.176893**
Percent in 10
mph pace
67.683582
+4.0558*
+10.4258**
+16.4950*8
0.90760528
-0.014089*
+0.050748**
+0.117640**
0.70694255
-0.049022*
+0.025462*
+0.152127**
0.23128281
-0.125339**
-0.073892**
-0.039559*
0.02918118
-0.042006**
-0.030543**
-0.066132**
0.0030505
-0.005033*
-0.004190*
-0.023996**
243,239
489,987
463,495
458,028
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.3 (b): ATR-175—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Two Weeks
2/13/06 to
2/26/06)
5.18181*
72.1753213
66.4353756
77.010939
78.2479404
79.4849417
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-84
Table 5.4 (a): ATR-175—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Regular Enforcement Period #2 and During the Previous Three Years
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(Two
Weeks
2/13/06 to
2/26/06)
Daily
Average
in Test
Period
56,257
4,018
-2,178
-1,284
-687
7,098
507
-730
-531
-1,149
243,239
17,374
—
—
—
Table 5.4 (b): ATR-175—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Regular Enforcement Period #2 and During the Previous Three Years
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.231283
0.231283
-0.125339
-0.073892
-0.039559
0.029181
0.029181
-0.042006
-0.030543
-0.066132
243,239
17,374
—
—
—
Test Period
(Two
Weeks
2/13/06 to
2/26/06)
A3-85
ATR-191: Enhanced Enforcement Period #2 and Regular Enforcement Period #2
As mentioned above, throughout both the Second Enhanced Enforcement Period and the
Second Regular Enforcement Period, there were problems with the speed data collected
at ATR-191. Because these data were unreliable, we were unable to make meaningful
comparisons with the historical speed data.
ATR-208: Enhanced Enforcement Period #2 and Regular Enforcement Period #2
Similarly, throughout the both the Second Enhanced Enforcement Period and Second
Regular Enforcement Period also, there were problems with the speed data collected at
ATR-208. Again because these data were unreliable, we were unable to make reliable
comparisons with the historical speed data.
A3-86
ATR-227: Enhanced Enforcement Period #2
Table 5.5 (a): ATR-227—Comparison of Speed Data from Enhanced Enforcement
Period #2, between 12/5/05 and 1/29/06, with Speed Data from the Previous Two
Years
Test Period
(12/5/05 to
1/29/06)
Decrease/Increase Decrease/Increase
Compared to
Compared to
Two Years
One Year Earlier
Earlier
(Four Weeks
Only 1/2/05 to
(All Eight Weeks)
1/29/05)
Measure
(All Eight Weeks)
Mean (mph)
70.62025
+0.670941**
-0.87439**
Percent in 10 mph
pace
66.5773
+2.197*
+4.2909**
0.872138
+0.03503**
-0.01387*
0.617927
+0.051258**
-0.06059**
0.196507
+0.005921
-0.07458**
0.021757
-0.00059
-0.01527**
0.003335
ns
-0.00265*
449,139
196,845
442,926
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.5 (b): ATR-227—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/5/05 to
1/29/06)
6.50792*
71.39916
65.43542
76.33068
77.76129
79.19191
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-87
Table 5.6 (a): ATR-227—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Enhanced Enforcement Period #2 and with the Two Previous Years
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test
Period
(12/5/05 to
1/29/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
88,259
1,576
+47
-598
9,771
174
-5
-122
449,139
8,020
—
—
Table 5.6 (b): ATR-227—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70 mph) During
Enhanced Enforcement Period #2 and with the Two Previous Years
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test Period
(12/5/05 to
1/29/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.196507
0.196507
+0.005921
-0.07458
0.021757
0.021757
-0.00059
-0.01527
449,139
8,020
—
—
A3-88
ATR-227—Regular Enforcement Period #2
Table 5.7 (a): ATR-227—Comparison of Speed Data from Regular Enforcement
Period #2, between 1/30/06and 2/26/06, with Speed Data from the Previous Two
Years
Measure
Test Period
(1/30/06 to
2/26/06
Decrease/Increase
Compared to
One Year Earlier
Decrease/Increase
Compared to
Two Years
Earlier
Mean (mph)
70.77257
-0.45778**
+0.432241**
Percent in 10 mph
pace
67.3569
+2.1818*
7.3275**
0.879427
-0.01272*
0.047932**
0.62799
-0.03531*
0.024127*
0.193668
-0.04191*
-0.03549*
0.021123
-0.00518*
-0.0104*
0.003678
-0.00038*
-0.00185*
203,379
216,677
204,308
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.7 (b): ATR-227—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to
2/26/06)
6.27902*
71.47345
65.58518
76.26541
77.71431
79.16321
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-89
Table 5.8 (a): ATR-227—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Regular Enforcement Period #2 and with the Two Previous Years
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test
Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
39,388
1,408
-304
-258
4,296
153
-38
-76
203,379
7,264
—
—
Table 5.8 (b): ATR-227—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 70 mph) During
Regular Enforcement Period #2 and with the Two Previous Years
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.19367
0.19367
-0.04191
-0.03549
0.02112
0.02112
-0.00518
-0.0104
203,379
7,264
—
—
A3-90
5.2. Speed Data from One ATR located Outside Enhanced Enforcement Zones
There was one ATR located on a Rural Freeway Outside the Enhanced Enforcement
Zones. It was ATR-200, on I-94, near Hasty in Wright County. During the MSMP, at
this ATR location the speed limit remained unchanged at 70 mph and there was no
change in enforcement. No historical speed data were available for either the Second
Enhanced or the Second Regular Enhancement Periods for ATR-200. However, we were
able to use Pre-MSMP speed data that came from a four-week period from 4/24/05 to
5/21/05. These data are compared with speed data from the Second Enhanced
Enforcement Period, and the Second Regular Enhancement Period.
Two tables are presented for each time period. In the first table, speed data from the Test
Year is compared with the historical speed data. In the second table, the focus is on
drivers who were traveling at least 5 mph and at least 10 mph above the speed limit—i.e.,
drivers traveling at 75 mph or more and at 80 mph or more. We also present the average
number of vehicles traveling above these speeds every day. Then, the table presents the
decrease in the number of vehicles relative to the number that were traveling at these
speeds before the MSMP was implemented.
A3-91
ATR-200—Enhanced Enforcement Period #2
Table 5.9 (a): ATR-200—Speed Data from Enhanced Enforcement Period #1
Compared with Pre-MSMP Speed Data
Measure
Test Period
(12/05/05 to 1/26/06)
Decrease/Increase
Compared to Pre-Test
Period
(4/24/05 to 5/21/05)
Mean (mph)
72.61433
-0.696075**
Percent in 10 mph
pace
63.0432
+10.3487**
0.918037
+0.034675**
0.743603
+0.038807*
0.364617
-0.044730*
0.042895
-0.10794**
0.004842
-0.046145**
1,970,991
1,206,904
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.9 (b): ATR-200—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/05/05 to 1/26/06)
6.18742*
73.21388
66.95023
78.33544
79.11251
79.88958
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-92
Table 5.10 (a): ATR-200—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Enhanced Enforcement Period #2 and the Pre-Test Period (4/24/05 to
5/21/05)
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Test Period
(12/05/05 to
1/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(4/24/05 to 5/21/05)
718,656
12,833
-1,574
84,546
1,510
-3,799
1,970,991
35,196
—
Table 5.10 (b): ATR-200—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Enhanced Enforcement Period #2 and the Pre-Test Period (4/24/05 to 5/21/05)
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Test Period
(12/05/05 to
1/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(4/24/05 to 5/21/05)
0.364617
0.364617
-0.04473
0.042895
0.042895
-0.10794
1,970,991
35,196
—
A3-93
ATR-200—Regular Enforcement Period #2
Table 5.11 (a): ATR-200—Speed Data from Regular Enforcement Period #2
Compared with Pre-MSMP Speed Data
Measure
Test Period
(1/30/06 to 2/26/06)
Decrease/Increase
Compared to
Pre-Test Period
(4/24/05 to 5/21/05)
Mean (mph)
72.80357
-0.50684**
Percent in 10 mph
pace
64.1249
+11.4304**
0.925797
+0.042435**
0.749776
+0.044980*
0.370673
-0.038673*
0.041053
-0.109783**
0.004616
-0.0463710**
941,792
1,206,904
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.11 (b): ATR-200—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to 2/26/06)
5.75875*
73.2943
67.15306
78.34738
79.10583
79.86428
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-94
Table 5.12 (a): ATR-200—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Regular Enforcement Period #2 and the Pre-Test Period (4/24/05 to 5/21/05)
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Test Period
(11/7/05 to
12/4/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(4/24/05 to 5/21/05)
349,097
12,468
-1301
38,663
1,381
-3,693
941,792
33,635
—
Table 5.12 (b): ATR-200—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Regular Enforcement Period #2 and the Pre-Test Period (4/24/05 to 5/21/05)
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Test Period
(11/7/05 to
12/4/05)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(4/24/05 to 5/21/05)
0.370673
0.370673
-0.038673
0.041053
0.041053
-0.109783
941,792
33,635
—
5.3. Overall Effect of the MSMP on Rural Freeways
In the MSMP, we obtained speed data from five ATRs located on Rural Freeways—four
of these ATRs were located Within Enhanced Enforcement Zones, while the remaining
ATR was located Outside the Enhanced Enforcement Zones. At the locations of all five
ATRs the speed limit remained unchanged at 70 mph.
In order to provide a brief overall summary of the effect of the MSMP, we focused on
drivers traveling at least 10 mph above the speed limit—i.e., those traveling at 80 mph or
more. Speed data from the ATRs Within Enhanced Enforcement Zones were combined.
In this case, we were only able to combine speed data from ATR-175 and ATR-227—the
speed data from ATR-191 and ATR-208 were not reliable in this period. Table 5.13
shows the results of this comparison for the Second Enhanced Enforcement Period.
A3-95
Table 5.13: Effect of MSMP on Rural Freeways during the Second Enhanced
Enforcement Period at Two ATRs (ATR-175 and ATR-227) Within Enhanced
Enforcement Zones
Sample Total
1,358,128*
Sample Total
1,465,562**
One Year Before MSMP
# Over 80 mph
70,884*
Second Enhanced Enforcement Period
# Over 80 mph
38,286**
% Over 80 mph
5.22*
% Over 80 mph
2.61**
Result: 50.00% Decrease in Drivers Traveling over 80 mph
*Numbers adjusted to account for limited availability of data from ATR-227 during the time period
**Numbers adjusted to account for limited availability of data from ATR-175 during the time period
Table 5.13 indicates that, for two of the four ATRs Within Enhanced Enforcement Zones
on Rural Freeways, during the Second Enhanced Enforcement Period, there was a
50.00% decrease in the number of drivers traveling at over 80 mph—i.e., 10 mph over
the speed limit—as compared to the month before the MSMP was implemented.
A similar comparison was conducted for the Second Regular Enforcement Period. For
this comparison speed data were available from ATR-175 and ATR-227—again the
speed data for ATR-191 and ATR-208 were not reliable. The results of this comparison
using speed data from the two ATRs are shown in Table 5.14.
Table 5.14: Effect of MSMP on Rural Freeways During the Second Regular
Enforcement Period at Two ATRs (ATR-175 and ATR-227) Within Enhanced
Enforcement Zones
Sample Total
706,664
Sample Total
689,857*
One Year Before MSMP
# Over 80 mph
40,580
Second Regular Enforcement Period
# Over 80 mph
18,492*
% Over 80 mph
5.74
% Over 80 mph
2.68*
Result: 46.69% Decrease in Drivers Traveling over 80 mph
*Numbers adjusted to account for limited availability of data from ATR-175 during the time period
Table 5.14 indicates that, for three of the four ATRs located Within Enhanced
Enforcement Zones on Rural Freeways, during the first Regular Enforcement Period,
there was a 46.69% decrease in the number of drivers traveling over 80 mph—i.e., 10
mph over the speed limit.
We also examined the difference between the speed data obtained during the Test Periods
from the ATR that was located Outside the Enhanced Enforcement Zones. We focused
on drivers traveling at 80 mph or more—10 mph above the speed limit. The results of
A3-96
this comparison for speed data obtained during the Second Enhanced Enforcement Period
are shown in Table 5.15.
Table 5.15: Effect of the MSMP on one ATR Outside the Enhanced Enforcement
Zones on a Rural Freeway During Second Enhanced Enforcement Period
Pre-MSMP Speed Data from 4/24/05 to 5/21/05
# Over 80 mph
% Over 80 mph
182,044
15.08
Second Enhanced Enforcement Period
Sample Total
# Over 80 mph
% Over 80 mph
1,970,991
84,546
4.29
Sample Total
1,206,904
Result: 71.55% Decrease in Drivers Traveling over 80 mph
Table 5.15 shows that, for the ATR located Outside Enhanced Enforcement Zones on a
Rural Freeway, during the Second Enhanced Enforcement Period, there was a 71.55%
decrease in the number of drivers traveling over 80 mph.
A similar comparison was conducted for the Second Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 5.16.
Table 5.16: Effect of MSMP at one ATR Outside the Enhanced Enforcement Zones
on a Rural Freeway During Second Regular Enforcement Period
Pre-MSMP Speed Data from 4/24/05 to 5/21/05
# Over 80 mph
% Over 80 mph
182,044
15.08
Second Regular Enforcement Period
Sample Total
# Over 80 mph
% Over 80 mph
941,792
38,663
4.11
Sample Total
1,206,904
Result: 72.74% Decrease in Drivers Traveling over 80 mph
Table 5.16 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
a Rural Freeway, during the Second Regular Enforcement Period there was a 72.74%
decrease in the number of drivers traveling over 80 mph.
For Rural Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
Zones should be treated with caution. It should be noted that the location of ATR that
was located Outside the Enhanced Enforcement Zones is between Enhanced Enforcement
Zones to both the North-West and the South-East. It is likely that most drivers passing
this ATR will have traveled through one or other of the Enhanced Enforcement Zones. [It
A3-97
should also be noted that there are no other ATRs Outside the Enhanced Enforcement
Zones on Rural Freeways that could have been considered for comparison purposes for
this study.] Also, the speed data used in the comparisons for the ATR located Outside the
Enhanced Enforcement Zones was from a different time period (4/24/05 to 5/21/05) from
the time periods for the Second Enhanced Enforcement Period (12/5 to 1/29) and the
Second Regular Enforcement Period (1/30 to 2/26).
A3-98
Section 6. Speed Data Obtained on Urban Freeways
We obtained speed data from four ATRs located on Urban Freeways. Three of these
ATRs were located Within Enhanced Enforcement Zones, while the remaining ATR was
located Outside the Enhanced Enforcement Zones. During the MSMP, at the locations of
the three ATRs Within the Enhanced Enforcement Zones, the speed limit was increased
from 55 mph to 60 mph and there was Enhanced Enforcement at various times. In
contrast, at the location of the ATR Outside the Enhanced Enforcement, the speed limit
remained unchanged at 55 mph and there was no change in the level of enforcement
during the MSMP.
In this section of the report, for the ATRs located Within Enhanced Enforcement Zones
and the single ATR located Outside the Enhanced Enforcement Zones, we present
comparisons of the speed data obtained during the Test Year with speed data obtained at
those same ATRs before the MSMP was implemented.
It should be noted that, for the three ATRs Within Enhanced Enforcement Zones, the
historical speed data is very limited. There is only speed data collected in the weeks just
before the MSMP began—specifically, the data is from September 2005 (with, in two
cases, data from the last two days in August, 2005). The available data is not the same
for all three ATRs—the actual time periods for which data were available are noted in the
comparison tables below. The result of comparing this August/September data with the
data collected at various times throughout the year should be considered with some
caution, as there may be seasonal effects that confound the effects of the MSMP.
There is historical speed data for the ATR located Outside the Enhanced Enforcement
Zones.
Comparisons using the speed data from the ATRs located Within Enhanced Enforcement
Zones are presented first. Then, we present comparisons using the speed data from the
ATR located Outside the Enhanced Enforcement Zones.
In making the comparisons between the speed data obtained during the Test Year and the
speed data obtained prior to the MSMP, we used two statistical tests. The first test was
used to examine differences in the mean speeds—for this we used the procedure for
comparing population means outlined by Kitchens (1987, p 369-373). The second test
was used to explore differences in the percentage of vehicles in the 10 mph pace and in
the differences in the proportions of vehicle traveling at various speeds. For this test, we
treated the distribution of speeds as a Bernoulli population—i.e., a population in which
each element is one of two possibilities, in this case, (1) in or out of the 10 mph pace, or
(2) above or below a selected speed (e.g., 75 mph). We then used the procedure for
comparing population proportions described by Kitchens (1987, pages 400-404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
A3-99
ATR in the time periods under consideration. Second, the tests were conducted using an
extremely conservative correction, with n-values equal to the number of hours in each
test period—the rationale for this was that it is possible, when traffic is congested, that
individual vehicles may travel at speeds which are not independent of each other.
6.1. Speed Data from ATRs located Within Enhanced Enforcement Zones
The three ATRs located Within Enhanced Enforcement Zones on Urban Freeways were
as follows: (1) ATR 100, on Highway 100 near Brooklyn Center in Hennepin County, (2)
ATR I94, on I-94 South of the 57th Street Bridge in Hennepin County, and (3) ATR35WCD, on I-35W, near Roseville in Ramsey County. At the locations of all three of
these ATRs, the speed limit was increased from 55 mph to 60 mph during the MSMP.
The effect of the MSMP on the speed data at each of these three ATRs is reported in this
section. It is reported ATR by ATR—with the effect of the MSMP in the first Enhanced
Enforcement Period followed by its effect in the first Regular Enhancement Period.
For each of the three ATRs Within Enhanced Enforcement Zones, two tables are
presented for each time period. In the first of these tables speed data from the Test Year
is compared with pre-MSMP speed data, which for these ATRs is limited to speed data
from September 2005 (and, in two cases, from the last two days in August, 2005)—the
specific dates from which data are available are noted in the table. In the second table for
each ATR, the focus is on drivers traveling at least 5 mph and at least 10 mph above the
new speed limit adopted for the MSMP—i.e., on drivers traveling at 65 mph or more and
at 70 mph or more. In this second table, we present the number (and proportion) of
vehicles traveling above these speeds throughout the eight-week Enhanced Enforcement
Period (from12/5/05 to 1/29/06) or the four-week Regular Enhancement Period (from
1/30/06 to 2/26/06). We also present the average number of vehicles traveling above
these speeds every day. Then, the table presents the decrease in the number of vehicles
relative to the number that were traveling at these speeds before the MSMP. It should be
noted that before the MSMP was adopted, these speeds (of 65 mph or more and 70 mph
or more) were 10 mph and 15 mph above the pre-MSMP speed limit.
A3-100
ATR-100—Enhanced Enforcement Period #2
Table 6.1 (a): ATR-100—Comparison of Speed Data from Enhanced Enforcement
Period #2 (from 12/5/05 to 1/29/06) with Speed Data from Two Weeks in September
2005
Measure
Test Period
(12/5/05 to 1/29/06)
Decrease/Increase
Compared to PreTest Period
(9/12/05 to 9/25/05)
Mean (mph)
57.534882
-3.0357**
Percent in 10 mph pace
50.904187
-6.6209**
0.18729828
-0.09595**
0.05339744
-0.03878**
0.0096193
-0.01561**
0.00285149
-0.00363*
0.00084571
-0.00091*
4,230,765
1,089,474
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.1 (b): ATR-100—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/5/05 to 1/29/06)
11.766860*
59.4480008
51.7183222
66.3927574
68.2598106
70.3880288
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-101
Table 6.2 (a): ATR-100—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph)
During Enhanced Enforcement Period #2 with Speed Data from Two Weeks in
September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(12/5/05 to
1/29/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
792,414
14,150
-7,240
225,912
4,034
-2930
4,230,765
75,549
—
Table 6.2 (b): ATR-100—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Enhanced Enforcement Period #2 with Speed Data from Two Weeks in September
2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(12/5/05 to
1/29/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
0.187298
0.187298
-0.09595
0.053397
0.053397
-0.03878
4,230,765
75,549
—
A3-102
ATR-100—Regular Enforcement Period #2
Table 6.3 (a): ATR-100—Comparison of Speed Data from Regular Enforcement
Period #2 (from 1/30/06 to 2/26/06) with Speed Data from Two Weeks in September
2005
Measure
Test Period
(1/30/06 to 2/26/06)
Decrease/Increase
Compared to PreTest Period
(9/12/05 to 9/25/05)
Mean (mph)
56.72893
-3.84165**
Percent in 10 mph pace
44.1874
-13.338**
0.208247
-0.074997**
0.06315
-0.02903*
0.010675
-0.01455*
0.003047
-0.00343*
0.000858
-0.00089*
2,140,206
1,089,474
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.3 (b): ATR-100—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to 2/26/06)
13.9434
59.97094
51.05656
67.00718
68.73016
71.25297
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-103
Table 6.4 (a): ATR-100—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph)
During Regular Enforcement Period #2 with Speed Data from Two Weeks in
September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(1/30/06 to
2/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
445,692
15,918
-5,732
135,154
4,827
-2,219
2,140,206
76,436
—
Table 6.4 (b): ATR-100—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Regular Enforcement Period #2 with Speed Data from Two Weeks in September
2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(1/30/06 to
2/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
0.208247
0.208247
-0.074997
0.06315)
0.06315
-0.02903
2,140,206
76,436
—
A3-104
ATR-I94—Enhanced Enforcement Period #2
Table 6.5 (a): ATR-I94—Comparison of Speed Data from Enhanced Enforcement
Period #2 (from 12/5/05 to 1/29/06) with Speed Data from Four Weeks in August
and September 2005
Measure
Test Period
(12/5/05 to 1/29/06)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
60.52502317
-3.01982**
Percent in 10 mph pace
55.8186293
+0.1606*
0.249835895
-0.16296**
0.111935926
-0.04499**
0.037112683
-0.02186*
0.011029403
-0.00921*
0.004361386
-0.00421*
6,491,285
3,409,707
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.5 (b): ATR-I94—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/5/05 to 1/29/06)
9.19117*
60.70292402
53.79478873
68.61986649
70.79760819
74.13881591
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-105
Table 6.6 (a): ATR-I94—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph)
During Enhanced Enforcement Period #2 with Speed Data from Four Weeks in
August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(12/5/05 to
1/29/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(8/29/05 to 9/25/05)
1,621,756
28,960
-18,890
726,608
12,975
-5,215
6,491,285
115,916
—
Table 6.6 (b): ATR-I94—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Enhanced Enforcement Period #2 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(12/5/05 to
1/29/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(8/29/05 to 9/25/05))
0.249836
0.249836
-0.16296
0.111936
0.111936
-0.04499
6,491,285
115,916
—
A3-106
ATR-I94—Regular Enforcement Period #2
Table 6.7 (a): ATR-I94—Comparison of Speed Data from Regular Enforcement
Period #2 (from 1/30/06 to 2/26/06) with Speed Data from Four Weeks in August
and September 2005
Measure
Test Period
(1/30/06 to 2/26/06)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
61.42337
-2.12148**
Percent in 10 mph pace
54.738
-0.9200*
0.268274
-0.14452**
0.121382
-0.03554*
0.038677
-0.0203*
0.011622
-0.00862*
0.004407
-0.00416*
3,225,030
3,409,707
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.7 (b): ATR-I94—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to 2/26/06)
8.07077*
61.24718
55.03939
69.0259
71.29268
74.31545
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-107
Table 6.8 (a): ATR-I94—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph)
During Regular Enforcement Period #2 with Speed Data from Four Weeks in
August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(1/30/06 to
2/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(8/29/05 to 9/25/05)
865,192
30,900
-16,646
391,462
13,981
-4,093
3,225,030
115,180
—
Table 6.8 (b): ATR-I94—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Regular Enforcement Period #2 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(1/30/06 to
2/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(8/29/05 to 9/25/05))
0.268274
0.268274
-0.14452
0.121382
0.121382
-0.03554
3,225,030
115,180
—
A3-108
ATR-35WCD—Enhanced Enforcement Period #2
Table 6.9 (a): ATR-35WCD—Comparison of Speed Data from Enhanced
Enforcement Period #2 (from 12/5/05 to 1/29/06) with Speed Data from Four Weeks
in August and September 2005
Measure
Test Period
(12/5/05 to 1/29/06)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
60.43974532
+0.431969**
Percent in 10 mph pace
40.1833818
-8.104**
0.393301842
+0.041453*
0.145760612
+0.028306*
0.04045301
+0.014119*
0.012271743
+0.007078*
0.004768296
+0.003579*
5,722,170
3,030,663
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.9 (b): ATR-35WCD—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/5/05 to 1/29/06)
12.43525*
62.75887903
51.72543605
69.91437006
72.1727117
74.54670936
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-109
Table 6.10 (a): ATR-35WCD—Comparison of the Daily Average Number of
Vehicles Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of
60 mph) During Enhanced Enforcement Period #2 with Speed Data from Four
Weeks in August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(12/5/05 to
1/29/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(8/29/05 to 9/25/05)
2,250,540
40,188
+4,236
834,067
14,894
+2,892
5,722,170
102,182
—
Table 6.10 (b): ATR-35WCD—Comparison of the Proportion of Vehicles Traveling
at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Enhanced Enforcement Period #2 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(12/5/05 to
1/29/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(8/29/05 to 9/25/05))
0.393302
0.393302
+0.041453
0.145761
0.145761
+0.028306
5,722,170
102,182
—
A3-110
ATR-35WCD—Regular Enforcement Period #2
Table 6.11: ATR-35WCD —Comparison of Speed Data from Regular Enforcement
Period #2 (from 1/30/06 to 2/26/06) with Speed Data from Four Weeks in August
and September 2005
Measure
Test Period
(1/30/06 to 2/26/06)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
61.44387527
+1.436099**
Percent in 10 mph pace
41.7706695
-6.517**
0.433218395
+0.08137**
0.164902885
+0.047449**
0.045820424
+0.019487*
0.014045135
+0.008851*
0.005405692
+0.004217*
2,938,384
3,030,663
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.11 (b): ATR-35WCD—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to 2/26/06)
11.92954*
63.57684308
53.02347772
70.62573805
72.7251236
74.82450916
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-111
Table 6.12 (a): ATR-35WCD—Comparison of the Daily Average Number of
Vehicles Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of
60 mph) During Regular Enforcement Period #2 with Speed Data from Four Weeks
in August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(1/30/06 to
2/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(8/29/05 to 9/25/05)
1,272,962
45,463
+8,539
484,548
17,305
+4,979
2,938,384
104,942
—
Table 6.12 (b): ATR-35WCD—Comparison of the Proportion of Vehicles Traveling
at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Regular Enforcement Period #2 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(1/30/06 to
2/26/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(8/29/05 to 9/25/05))
0.433218
0.433218
+0.08137
0.164903
0.164903
+0.047449
2,938,384
104,942
—
A3-112
6.2. Speed Data from One ATR located Outside Enhanced Enforcement Zones
There was one ATRs located on an Urban Freeway Outside the Enhanced Enforcement
Zones. It was ATR-335, on I-35W at County Road 53 in Anoka County. During the
MSMP, at this ATR location the speed limit remained unchanged at 55 mph and there
were no changes in enforcement. For ATR-335, the speed data obtained during 2005,
when the MSMP occurred, was compared with historical speed data. Comparisons are
presented here for the eight-week time period between 12/5/05 and 1/29/06, when the
Second Enhanced Enforcement Period occurred during the MSMP, and then for the fourweek time period between 1/30/06 and 2/26/06, when the Second Regular Enhancement
Period occurred.
Two tables are presented for each of these time periods. In the first table speed data from
the Test Year is compared with the historical speed data. We include speed data from the
three years prior to the MSMP in this table. In the second table, the focus is on drivers
who were traveling at least 5 mph and at least 10 mph above the new speed limit that was
adopted on the comparable roads in the Enhanced Enforcement zones during the
MSMP—i.e., drivers traveling at 65 mph or more and at 70 mph or more. It should be
noted that during the MSMP, as well as during the three years before it was adopted,
these speeds (65 mph or more and 70 mph or more) were 10 mph and 15 mph above the
actual speed limit at the location of ATR-335. In this second table, we present the
number (and proportion) of vehicles traveling above these speeds throughout the Second
Enhanced Enforcement Period of eight weeks, between 12/5/05 and 1/29/06, or the
Second Regular Enhancement Period of four weeks, between 1/30/06 and 2/26/06. We
also present the average number of vehicles traveling above these speeds every day.
Then, the table presents the decrease in the number of vehicles relative to the number that
were traveling at these speeds before the MSMP was implemented.
A3-113
ATR-335—Enhanced Enforcement Period #2
Table 6.13 (a): ATR-335—Speed Data from Enhanced Enforcement Period #2 (from
12/5/05 to 1/29/06) Compared with Speed Data from Three Previous Years
Measure
Test Period
(12/5/05 to
1/29/06)
Decrease/Increase
as Compared to
One Year Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
Standard
deviation (mph)
69.02317
-0.68578**
+0.087315**
-4.54848**
8.398274
—
—
—
Percent in 10
mph pace
57.8252
+4.4164**
+7.6249**
-2.9309*
0.777356
+0.003366*
+0.028178*
-0.15600**
0.495977
-0.03464*
+0.001483*
-0.26141**
0.162248
-0.06816*
-0.05503**
-0.24376**
0.038421
-0.03274**
-0.02073**
-0.07933**
0.009363
-0.00621*
-0.00089*
-0.01064**
2,181,300
2,179,324
2,161,836
2,089,039
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.13 (b): ATR-335—Additional Speed Data from Enhanced Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(12/5/05 to
1/29/06)
8.39827*
69.92852
62.49636
75.49455
77.5135
79.53246
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-114
Table 6.14 (a): ATR-335—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 ph)
During Enhanced Enforcement Period #2 and During the Previous Three Years
Measure
Number of vehicles at
60 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(12/5/05 to
1/29/06)
Daily
Average
in Test
Period
1,695,645
30,279
+131
+1,098
-6,076
1,081,875
19,319
-1,349
+58
-10,182
2,181,300
38,952
—
—
—
Table 6.14 (b): ATR-335—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Enhanced Enforcement Period #2 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(12/5/05 to
1/29/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.77736
0.77736
+0.003366
+0.028178
-0.15600
0.49597
0.49597
-0.03464
+0.001483
-0.26141
2,181,300
38,952
—
—
—
A3-115
ATR-210—Regular Enforcement Period #2
Table 6.15 (a): ATR-335—Speed Data from Regular Enforcement Period #2 (from
1/30/06 to 2/26/06) Compared with Speed Data from Three Previous Years
Measure
Test Period
(1/30/06 to
2/26/06)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
69.71321
-1.34075**
+1.69097**
-3.06472**
Percent in 10
mph pace
61.0475
+6.5018**
+16.0865**
+3.8798*
0.806328
-0.01844*
+0.111125**
-0.09919**
0.539322
-0.05814**
+0.074796**
-0.1909**
0.18292
-0.08606**
-0.01832*
-0.20918**
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.043538
-0.04714**
-0.00592*
-0.06840**
0.009819
-0.01036*
+0.0005959*
-0.01024*
Vehicle Total
1,105,817
1,133,251
1,081,635
1,036,473
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.15 (b): ATR-335—Additional Speed Data from Regular Enforcement
Period #2
Measure
Standard deviation
(mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(1/30/06 to
2/26/06)
7.98759*
70.55165
63.33224
76.18093
77.97456
79.76819
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A3-116
Table 6.16 (a): ATR-335—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 ph)
During Regular Enforcement Period #2 and During the Previous Three Years
Measure
Number of vehicles at
60 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
891,651
31,845
-728
+4,389
-3,917
596,391
21,300
-2,296
+2,954
-7,539
1,105,817
39,493
—
—
—
Table 6.16 (b): ATR-335—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Regular Enforcement Period #2 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(1/30/06 to
2/26/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.80633
0.80633
-0.01844
+0.11113
-0.09919
0.53932
0.53932
-0.05814
+0.07480
-0.19090
1,105,817
39,493
—
—
—
A3-117
6.3. Overall Effect of MSMP on Urban Freeways During the Second Test Period
In the MSMP, we obtained speed data from four ATRs located on Urban Freeways—
three of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining ATR was located Outside the Enhanced Enforcement Zones. The speed limit
was increased from 55 mph to 60 mph at the locations of the three ATRs Within
Enhanced Enforcement Zones, while the speed limit remained unchanged at 55 mph at
location of the ATR Outside the Enhanced Enforcement Zones
In order to provide a brief overall summary of the effect of the MSMP, we focused on
drivers traveling at least 10 mph above the new speed limit. Speed data from the three
ATRs Within Enhanced Enforcement Zones were combined. Then, we compared speed
data collected during the Second Enhanced Enforcement Period with pre-MSMP speed
data that were collected just before the MSMP began—these data were collected over
two weeks during September 2005 for ATR-100, and over four weeks during August and
September 2005 for ATR-I94 and ATR-35WCD. When the pre-MSMP data were
collected the speed limit at the locations of the three ATRs was still 55 mph. Table 6.17
shows the results of this comparison for the Second Enhanced Enforcement Period, form
12/5/05 to 1/29/06.
Table 6.17: Effect of MSMP on Urban Freeways during the Second Enhanced
Enforcement Period, from 12/5/05 to 1/29/06, at Three ATRs Within Enhanced
Enforcement Zones
Sample Total
8,619,318*
Sample Total
16,444,220
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879*
Second Enhanced Enforcement Period
# Over 70 mph
1,786,587
% Over 70 mph
12.67*
% Over 70 mph
10.86
Result: 14.28% Reduction in Drivers over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-100 during the pre-MSMP time
period
Table 6.17 indicates that, for the three ATRs Within Enhanced Enforcement Zones on
Urban Freeways, during the Second Enhanced Enforcement Period, there was a 17.5%
decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the new
speed limit—as compared to the month before the MSMP was implemented.
A similar comparison was conducted for the Second Regular Enforcement Period. The
results of this comparison using speed data from the three ATRs are shown in Table 6.18.
A3-118
Table 6.18: Effect of MSMP on Urban Freeways during the Second Regular
Enforcement Period, from 1/30/06 to 2/26/06, at Three ATRs Within Enhanced
Enforcement Zones
Sample Total
8,619,318*
Sample Total
8,303,620
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879*
Second Regular Enforcement Period
# Over 70 mph
1,011,164
% Over 70 mph
12.67*
% Over 70 mph
12.18
Result: 3.87% Reduction in Drivers over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-100 during the pre-MSMP time
period
Table 6.18 indicates that, for the three ATRs located Within Enhanced Enforcement
Zones on Urban Freeways, during the Second Regular Enforcement Period, there was a
3.87% decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the
new speed limit—as compared to the month before the MSMP was implemented.
We also examined the difference between the speed data obtained during the Test Periods
from the ATR that was located Outside the Enhanced Enforcement Zones. For this ATR
location there was no change in the level of enforcement during the MSMP and no
change in the speed limit. Again, we focused on drivers traveling at 70 mph or more—
while this is 10 mph above the new speed limit Within Enhanced Enforcement Zones, it is
15 mph above the actual speed limit at the location of the ATR Outside Enhanced
Enforcement Zones. The results of this comparison for speed data obtained during the
Second Enhanced Enforcement Period are shown in Table 6.19.
Table 6.19: Effect of MSMP at one ATR Outside the Enhanced Enforcement Zones
on an Urban Freeway during Second Enhanced Enforcement Period, from 12/5/05
to 1/29/06
Sample Total
2,179,324
Sample Total
2,181,300
One Year Before MSMP
# Over 70 mph
1,156,395
Second Enhanced Enforcement Period
# Over70 mph
1,081,875
% Over 70 mph
53.06
% Over 70 mph
49.60
Result: 6.52% Decrease in Drivers Traveling over 70 mph
Table 6.19 shows that, for the ATR located Outside Enhanced Enforcement Zones on an
Urban freeway, during the Second Enhanced Enforcement Period, there was a 6.52%
decrease in the number of drivers traveling over 70 mph—i.e., 10 mph above the new
A3-119
speed limit Within Enhanced Enforcement Zones (and 15 mph above the current speed
limit Outside the Enhanced Enforcement Zones).
A similar comparison was conducted for the Second Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 6.20.
Table 6.20: Effect of MSMP on Rural Freeway during Second Regular
Enforcement Period, from 1/30/06 to 2/26/06 at one ATR Outside the Enhanced
Enforcement Zones
Sample Total
1,133,251
Sample Total
1,105,817
One Year Before MSMP
# Over 70 mph
677,070
Second Regular Enforcement Period
# Over 70 mph
596,391
% Over 70 mph
59.75
% Over 70 mph
53.93
Result: 9.74% Decrease in Drivers Traveling over 70 mph
Table 6.20 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
an Urban Freeway, during the Second Regular Enforcement Period there was a 9.74%
decrease in the number of drivers traveling over 70 mph—i.e., at 10 mph or more above
the new speed limit Within Enhanced Enforcement Zones (and 15 mph or more above the
current speed limit Outside Enhanced Enforcement Zones).
For Urban Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
Zones should be treated with caution. It should be noted that the location of ATR that
was located Outside the Enhanced Enforcement Zones is only a few miles to the North of
an Enforced Enforcement Zone. And, most of the drivers traveling North past this ATR
will have traveled through that Enhanced Enforcement Zone. [It should also be noted
that, the locations of all the other ATRs Outside the Enhanced Enforcement Zones on
Urban Freeways that might have been considered for comparison purposes for this study
are also very close to Enhanced Enforcement Zones.]
A3-120
Section 7. Crash Data
During the Second MSMP Test Period, crash data were available for all Minnesota trunk
highways. These trunk highways included 2-Lane/2-Way Highways, 4-Lane Highways,
Rural Freeways, and Urban Highways. Some of these highways had changes in speed
limits during the MSMP, some had enhanced enforcement during the MSMP, and speed
data were available from some of them. In all, there were twelve combinations of Road
Type, Speed Limits, and Enforcement Status. Table 7.1 lists the twelve combinations—
along with the availability of speed data and the total length of roadway for each
combination.
Table 7.1: Combinations of Trunk Highway Type, Speed Limits During the MSMP,
and Enforcement Status (with Availability of Speed Data and Length of Roadway)
Type of
Roadway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
Speed Limits
Increased—from 55
mph to 60 mph
Unchanged at 55
mph
Increased—from 55
mph to 60 mph
4-Lane Divided
Highway
4-Lane Divided
Highway
Unchanged at 65
mph
Unchanged at 65
mph
Rural Freeway
Unchanged at 70
mph
Unchanged at 70
mph
Rural Freeway
Urban Freeway
Urban Freeway
Urban Freeway
Urban Freeway
Urban Freeway
Increased—from 55
mph to 60 mph
Unchanged at 55
mph
Unchanged at 60
mph
Unchanged at 60
mph
Unchanged at 55
mph
Enforcement
Status
(Within/Outside
Enhanced
Enforcement
Zone)
Within
Outside
Outside
Within
Outside
Availability of
Speed Data
Available/
Unavailable
Available
(ATR)
Available
(ATR & Tube)
Available
(Tube)
Total Length of
Highways
Segments
(in Miles)
316.790
Available
(ATR & Tube)
Available
(ATR)
52.219
7,593.783
474.511
550.525
Available
(ATR & Tube)
Available
(ATR)
265.246
27.337
89.397
Within
Available
(ATR)
Available
(ATR)
Unavailable
Outside
Unavailable
73.377
Within
Unavailable
11.234
Within
Outside
Within
Outside
A3-121
459.835
4.052
Table 7.1 shows that crash data were available from all the combinations for which speed
data were available, as well as from three combinations for which we did not have speed
data. The table also shows that there were great differences in the length of roadway in
each combination—the range was from 7,593.783 miles of 2-Lane/2-Way Highway, with
unchanged speed limits, that were outside the enhanced enforcement zones to 4.052 miles
of Urban Freeway, with unchanged speed limits, that were within the enhanced
enforcement zones.
While an enormous amount of speed data was available for analysis purposes, in contrast
there were orders of magnitude less crash data. Since crash data becomes more stable as
the sample size increases, instead of analyzing them for particular road segments, we
analyzed the crash data in terms of the twelve combinations listed in Table 7.1. Also, we
combined the crash data from the Second Enhanced Enforcement Period and Second
Regular Enforcement Period with the crash data from the First Enhanced and Regular
Enforcement Periods. Comparisons of the crash data from the Second and First MSMP
Test Period with historical crash data, combined over the previous five years, for the
same time period (between 9/26 and 2/26) are presented in Tables 7.2 through 7.13.
However, please note that the Average Daily Traffic (ADT) values used in Tables 7.2
through 7.13 are ADT values calculated for traffic levels on the various highways in
2005—this is because ADT values for 2006 will not be available until 2007.
Table 7.2: Crash Data for 2-Lane/2-Way Highways for which the Speed Limit Was
Increased, from 55 mph to 60 mph, and that Were Within the Enhanced
Enforcement Zones during the MSMP
Length (miles)
Average Daily Traffic
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 2/26/06)
316.790
3,959.0038
3
4
22
Historical Crash
Data
316.790
3,876.057
15
30
79
47
97
115
191
0.9889
1.5843
1.5533
545
766
0.8102
1.2385
1.5865
A3-122
7.3: Crash Data for 2-Lane/2-Way Highways for which the Speed Limit Was
Unchanged, at 55 mph, and that Were Outside the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Number of Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 2/26/06)
7,593.783
2,539.9186
37
53
270
Historical Crash
Data
7,593.783
2,468.993
257
370
1801
558
2,532
1,961
2,879
0.9693
1.4423
1.2457
10,548
15,508
1.0742
1.6472
1.7802
Table 7.4: Crash Data for 2-Lane/2-Way Highways for which the Speed Limit Was
Increased, from 55 mph to 60 mph, and that Were Outside the Enhanced
Enforcement Zones during the MSMP
Length (miles)
Average Daily Traffic
Number of Fatal Crashes
Number of A Injury
Crashes
Number of B Injury
Crashes
Number of C Injury
Crashes and Unknowns
Number of Property
Damage Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 2/26/06)
474.511
2,745.0887
2
Historical Crash
Data
474.511
2,709.713
11
2
21
13
78
28
109
95
140
0.6979
1.0369
0.9970
401
620
0.6262
1.0020
1.1110
A3-123
Table 7.5: Crash Data for 4-Lane Divided Highways for which the Speed Limit Was
Unchanged, at 65 mph, and that Were Within the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Number of Fatal Crashes
Number of A Injury
Crashes
Number of B Injury
Crashes
Number of C Injury
Crashes and Unknowns
Number of Property
Damage Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 2/26/06)
52.219
16,844.8455
1
Historical Crash
Data
52.219
15,951.606
4
2
12
9
51
20
130
73
105
0.7751
1.1295
0.7382
421
618
0.9635
1.4063
0.6236
Table 7.6: Crash Data for 4-Lane Divided Highways for which the Speed Limit Was
Unchanged, at 65 mph, and that Were Outside the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Number of Fatal Crashes
Number of A Injury
Crashes
Number of B Injury
Crashes
Number of C Injury
Crashes and Unknowns
Number of Property
Damage Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 2/26/06)
550.525
12,279.2783
7
Historical Crash
Data
550.525
11,745.3069
38
14
86
58
512
165
822
573
817
0.7848
1.1219
0.6724
3,326
4,694
0.9428
1.3959
0.7632
A3-124
Table 7.7: Crash Data for Rural Freeways for which the Speed Limit Was
Unchanged, at 70 mph, and that Were Within the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Number of Fatal Crashes
Number of A Injury
Crashes
Number of B Injury
Crashes
Number of C Injury
Crashes and Unknowns
Number of Property
Damage Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 2/26/06)
265.246
21,345.3377
6
Historical Crash
Data
265.246
20,068.640
37
9
60
70
287
107
522
588
780
0.8946
1.2364
0.6881
2,553
3,459
0.8439
1.1913
0.9027
Table 7.8: Crash Data for Rural Freeways for which the Speed Limit Was
Unchanged, at 70 mph, and that Were Outside the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Number of Fatal Crashes
Number of A Injury
Crashes
Number of B Injury
Crashes
Number of C Injury
Crashes and Unknowns
Number of Property
Damage Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 2/26/06)
459.835
22,663.6713
4
Historical Crash
Data
459.835
21,699.037
45
10
48
97
513
198
895
806
1,115
0.6947
0.9677
0.2492
4,200
5,701
0.7431
1.0357
0.5865
A3-125
Table 7.9: Crash Data for Urban Freeways for which the Speed Limit Was
Increased, from 55 mph to 60 mph, and that Were Within the Enhanced
Enforcement Zones during the MSMP
Length (miles)
Average Daily Traffic
Number of Fatal Crashes
Number of A Injury
Crashes
Number of B Injury
Crashes
Number of C Injury
Crashes and Unknowns
Number of Property
Damage Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 2/26/06)
27.337
102,733.2401
2
Historical Crash
Data
27.337
100,988.341
6
2
28
17
151
103
435
306
430
0.9942
1.3434
0.4624
1,883
2,503
1.1775
1.5750
0.2823
Table 7.10: Crash Data for Urban freeways for which the Speed Limit Was
Unchanged, at 55 mph, and that Were Outside the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Number of Fatal Crashes
Number of A Injury
Crashes
Number of B Injury
Crashes
Number of C Injury
Crashes and Unknowns
Number of Property
Damage Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 2/26/06)
89.397
90,578.2219
7
Historical Crash
Data
89.397
89,755.688
15
4
47
60
492
373
1,803
1,532
1,976
1.5846
2.0120
0.5613
8,844
11,201
1.18129
2.2966
0.2428
A3-126
Table 7.11: Crash Data for Urban Freeways for which the Speed Limit Was
Unchanged, at 60 mph, and that Were Within the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Number of Fatal Crashes
Number of A Injury
Crashes
Number of B Injury
Crashes
Number of C Injury
Crashes and Unknowns
Number of Property
Damage Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 2/26/06)
4.052
97,906.2409
0
Historical Crash
Data
4.052
96,395.489
4
1
3
3
18
7
46
39
50
0.8184
1.0803
0.0000
262
333
1.1072
1.4630
1.3300
Table 7.12: Crash Data for Urban Freeways for which the Speed Limit Was
Unchanged, at 60 mph, and that Were Outside the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Number of Fatal Crashes
Number of A Injury
Crashes
Number of B Injury
Crashes
Number of C Injury
Crashes and Unknowns
Number of Property
Damage Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 2/26/06)
73.377
91,627.8252
1
Historical Crash
Data
73.377
93,431.901
12
7
22
41
299
199
961
771
1,019
0.9842
1.2797
0.0966
4,515
5,809
1.1004
1.4173
0.2273
A3-127
Table 7.13: Crash Data for Urban Freeways for which the Speed Limit Was
Unchanged, at 55 mph, and that Were Within the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Number of Fatal Crashes
Number of A Injury
Crashes
Number of B Injury
Crashes
Number of C Injury
Crashes and Unknowns
Number of Property
Damage Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 2/26/06)
11.234
128,504.4084
0
Historical Crash
Data
11.234
126,003.032
5
0
3
11
83
82
382
238
331
1.4889
1.9567
0.0000
1,530
2,003
1.8377
2.3671
0.4587
The crash data presented in Tables 7.2 through 7.13 are summarized below in Table 7.14.
The table shows the Crash Rate, the Severity Rate, and the Fatal Crash Rate for each
combination of road type, speed limit condition both Within and Outside the Enforcement
Zones between 9/26/05 and 2/26/06 (the first 22 weeks of the MSMP).
A3-128
Table 7.14: Crash Rate, Severity Rate, and Fatal Crash Rate for Each Combination
of Trunk Highway Type, Speed Limits During the MSMP, and Enforcement Zone
During the First 22-Weeks of the MSMP
Road Type/Speed Limit
2 Lane/2-Way Highway
Increase—55 to 60 mph
2 Lane/2-Way Highway
No Change—55 mph
4 Lane/Divided Highway
No Change—65 mph
Rural Freeway
Unchanged—70 mph
Urban Freeway
Increase—55 to 60 mph
Urban Freeway
No Change—55 mph
Urban Freeway
No Change—60 mph
Within
Crash
Rate
Severity
Rate
Fatal
Crash
Rate
0.9889
1.5843
1.5533
—
—
0.7751
Outside
Crash
Rate
Severity
Rate
Fatal
Crash
Rate
0.6979
1.0369
0.9970
—
0.9693
1.4423
1.2457
1.1295
0.7382
0.7848
1.1219
0.6724
0.8946
1.2364
0.6881
0.6947
0.9677
0.2492
0.9942
1.3434
0.4624
—
—
—
1.4889
1.9567
0.0000
1.5846
2.0120
0.5613
0.8184
1.0803
0.0000
0.9842
1.2797
0.09666
A3-129
Section 8. Citation Data
During the Second MSMP Enhanced Enforcement Period citation data were collected for
the highways on which there was Enhanced Enforcement. In all, citation data were
collected for 32 regions—14 regions have ATRs in them, seven regions will have Tubes
in the Fourth Enhanced Enforcement Period, and the remaining eleven regions are next to
regions where there are ATRs or Tubes. The citation data for the 14 regions in which
there are ATRs are reported in the tables below; there is one table for each road type
included in the MSMP—i.e., 2-Lane/2-Way Highways, 4-Lane Highways, Rural
Freeways, and Urban Highways. The tables list the ATRs that were on the various road
types and their locations. The Tables also present the Number of Speed Citations and the
Number of Speed Warnings given during the Second Enhanced Enforcement Period, the
Number of Vehicles that were Stopped and the Number of Hours of Enforcement.
Table 8.1: Citation Data for 2-Lane/2-Way Highways on Which ATRs Were
Located
ATR
210
219
220
Location
US-71, 1 m. North of
Blackduck, Beltrami
US-2, South East of
Warba, Itasca
US-71, South of CR 89,
Hubbard
Total
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
120
534
748
510
175
458
705
669
180
782
1,098
575
475
1,774
2,551
1,754
Table 8.2: Citation Data for 4-Lane Divided Highways on Which ATRs Were
Located
ATR
172
187
188
197
Location
US-10, West of
Dilworth, Clay
US-10, 0.8 miles West
of Rice, Benton
US-52, North of
Rochester, Olmstead
SR-60, 0.7 miles West
of junction with SR-4,
(St. James) Watonwan
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
183
176
359*
252
257
304
642
471
213
411
691
468
100
289
421
248
1,180
2,113*
1,439
753
Total
*Adjusted, but probably an underestimate
A3-130
Table 8.3: Citation Data for Rural Freeways on Which ATRs Were Located
ATR
175
191
208
227
Location
I-94, 0.5 miles South
East of Saulk Centre,
Stearns
I-35, North of
Wyoming, Chisago
I-35, North of
Owatanna, Steele
I-90, East of Alden,
Freeborn
Total
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
309
281
644
474
271
222
521
452
85
223
342
225
93
156
285
224
758
882
1,792
1,375
Table 8.4: Citation Data for Urban Freeways on Which ATRs Were Located
ATR
100
I94
35WCD
Total
Location
Highway 100, near
Brooklyn Center,
Hennepin
I-94, South of 57th
Street Bridge,
Hennepin
I-35W, near Roseville,
Ramsey
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
484
330
929
623
341
74
563
504
647
101
1,093
630
1,472
505
2,585
1,757
The citation data for the individual highways that are presented in Tables 8.1 through 8.4
are summarized in Table 8.5. This table presents, for each of the four highway types, the
Number of Speed Citations and the Number of Speed Warnings that were given during
the Second Enhanced Enforcement Period, as well as the Number of Vehicles that were
Stopped and the Number of Hours of Enforcement.
A3-131
Table 8.5: Citation Data for the Four Types of Highways on Which ATRs Were
Located
Type of
Highway
2-Lane/2-Way
Highway
4-Lane
Divided
Highway
Rural Freeway
Urban
Freeway
Number of
Speed Citations
Number of
Speed Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
475
1,774
2,551
1,754
753
758
1,180
882
2,113*
1,792
1,439
1,375
1,472
505
2,585
1,757
4,341
9,041*
6,325
3,458
*Probably an underestimate
Total
A3-132
Appendix 4
Minnesota Speed Management Project: Deliverable #5—
Data Analysis for the Third Test Period
Kathleen A. Harder, Ph.D. and John R. Bloomfield, Ph.D.
Center for Human Factors Systems Research and Design
University of Minnesota, Suite 225
1425 University Ave. S.E.
Minneapolis, MN 55414
Contents
Page
Section 1. Introduction …………………………………………………………………..3
1.1 Background ……………………………………………………………….3
1.2 Organization of this Report ……………………………………………..5
Section 2. Summary of Findings during the Third MSMP Test Period ………..………6
2.1 Overall Effect of the MSMP during the Third Enhanced
Enforcement and Third Regular Enforcement Period …………………….6
2.2 Effect of the MSMP on 2-Lane/2-Way Highways …………………………7
2.3 Effect of the MSMP on 4-Lane Divided Highways ………………………10
2.4 Effect of the MSMP on Rural Freeways …………………………………13
2.5 Effect of the MSMP on Urban Freeways ………………………………...15
2.6 Crash Rates During the Third MSMP Period……………………………18
2.7 Citation Data During the Third MSMP Period ………………………….19
Section 3. Speed Data Obtained on 2-Lane/2-Way Highways …..……………………20
3.1 Speed Data from ATRs Located Within Enhanced
Enforcement Zones ………………………………………………………20
3.2 Speed Data from ATRs Located Outside Enhanced
Enforcement Zones ………………………………………………………34
3.3 Overall Effect of the MSMP on 2-Lane/2-Way Highways ………………50
Section 4. Speed Data Obtained on 4-Lane Divided Highways ….…………………..54
4.1 Speed Data from ATRs Located Within Enhanced
Enforcement Zones ………………………………………………………54
4.2 Speed Data from One ATR Located Outside Enhanced
Enforcement Zones ………………………………………………………72
4.3 Overall Effect of the MSMP on 4-Lane Divided Highways ……………..76
Section 5. Speed Data Obtained on Rural Freeways …………………………………80
5.1 Speed Data from ATRs Located Within Enhanced
Enforcement Zones ………………………………………………………80
5.2 Speed Data from One ATR Located Outside Enhanced
Enforcement Zones ………………………………………………………94
5.3 Overall Effect of the MSMP on Rural Freeways ………………………..98
Section 6. Speed Data Obtained on Urban Freeways…………………………………102
6.1 Speed Data from ATRs Located Within Enhanced
Enforcement Zones………………………………………………………103
6.2 Speed Data from One ATR Located Outside Enhanced
Enforcement Zones ……………………………………………………116
6.3 Overall Effect of the MSMP on Urban Freeways ………………………120
Section 7. Crash Data ………………………………………………………………...124
Section 8. Citation Data ………………………………………………………………133
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Section 1. Introduction
1.1 Background
This report contains the results of the analysis of data obtained during the third testing
period of the Minnesota Speed Management Program (MSMP). The Minnesota Speed
Management Program (MSMP) is a cooperative project between the Minnesota
Department of Transportation (Mn/DOT) and the Minnesota Department of Safety
(DPS). The program, which ran from 9/26/05 to 8/13/06, involved:
• Raising the speed limit on select roadways in Minnesota from 55 mph to 60 mph
in order to align the speed limit more closely with the design speed of the
roadways.
• Increasing the presence of enforcement officers along selected areas of these
roadways and other high-design roadways for selected periods of time.
The MSMP involved the following four types of roadway—(1) 2-Lane/2-Way Highways,
(2) 4-Lane Divided Highways, (3) Rural Freeways, and (4) Urban Freeways.
This report presents the University of Minnesota’s assessment of effectiveness of the
MSMP during its third test period, between 2/27/06 and 5/21/06. The test period had two
phases—the Third Enhanced Enforcement Period, lasting eight weeks between 2/27/06
and 4/23/06; and the Third Regular Enforcement Period, lasting four weeks between
4/24/06 and 5/21/06.
In the Third Enhanced Enforcement Period and the Third Regular Enforcement Period,
we analyzed speed data collected by Mn/DOT in order to determine whether there were
changes in speeds as a result of the MSMP. In addition, we analyzed crash data to
determine whether there were changes in crash rates. Some historical speed data and
crash data were available for comparison purposes—where possible, we compared the
data obtained in these two phases with historical data. Also, we analyzed citation data—
in this case however, there no historical citation data were available.
The speed data that were provided by Mn/DOT were collected from a number of
Automated Traffic Recorders (ATRs). [We expect the ATR data will be augmented by
Tube data in the final test period.] The ATRs are listed in Table 1.1. The ATRs are
organized in the table in terms of the type of roadway at which they are located—i.e.,
whether they are on 2-Lane/2-Way Highways, 4-Lane Divided Highways, Rural
Freeways, or Urban Freeways. The table lists their locations, the speed limit (and
whether or not it was changed for the MSMP), and whether they were located Within or
Outside an Enhanced Enforcement Zone.
A4-3
Table 1.1: ATRs Organized by Road Type
Type of
roadway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
ATR
210
219
220
179
198
199
222
4-Lane Divided
Highway
197
4-Lane Divided
Highway
4-Lane Divided
Highway
4-Lane Divided
Highway
4-Lane Divided
Highway
172
Rural Freeway
175
Rural Freeway
191
Rural Freeway
208
Rural Freeway
227
Rural Freeway
200
Urban Freeway
100
Urban Freeway
I94
Urban Freeway
35WC
D
335
Urban Freeway
187
188
353
Location
US-71, 1 m. North of
Blackduck, Beltrami
US-2, South East of Warba,
Itasca
US-71, South of CR 89,
Hubbard
USTH 59, South of Garvin,
Lyon
USTH 212, East of TH 23,
Chippewa
USTH 75, 0.55 m. N of Co
Rd. 69, Pipestone
MNTH 65, near Pliny,
Aitkin
Speed limit
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Unchanged at 55 mph
Within/
Outside
Enforcement
Zone
Within
Within
Within
Outside
Unchanged at 55 mph
Outside
Unchanged at 55 mph
Outside
Unchanged at 55 mph
Outside
SR-60, 0.7 miles West of
junction with SR-4, (St.
James) Watonwan
US-10, West of Dilworth,
Clay
US-10, 0.8 miles West of
Rice, Benton
US-52, North of Rochester,
Olmstead
TH 169, South of CR
59,North of Jordan, Scott
Unchanged at 65 mph
Within
Unchanged at 65 mph
Within
Unchanged at 65 mph
Within
Unchanged at 65 mph
Within
Unchanged at 65 mph
Outside
I-94, 0.5 miles South East
of Saulk Centre, Stearns
I-35, North of Wyoming,
Chisago
I-35, North of Owatanna,
Steele
I-90, East of Alden,
Freeborn
I-94, Hasty, Wright
Unchanged at 70 mph
Within
Unchanged at 70 mph
Within
Unchanged at 70 mph
Within
Unchanged at 70 mph
Within
Unchanged at 70 mph
Outside
Highway 100, near
Brooklyn Center, Hennepin
I-94, South of 57th Street
Bridge, Hennepin
I-35W, near Roseville,
Ramsey
I-35W at County Road 53,
Anoka
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Unchanged at 55 mph
Within
A4-4
Within
Within
Outside
From the speed data obtained with the ATRs, we derived several speed measures for the
Third Enhanced Enforcement Period and Third Regular Enforcement Period. The same
measures were also derived from historical speed data that were obtained during the same
calendar time periods. Where possible, we used historical speed data from the three years
prior to the MSMP. In order to compare the MSMP speed data with the historical data,
we conducted a series of statistical tests in which the following measures were
compared—(1) the mean speed, (2) the percentage of vehicles in the 10 mph pace, (3) the
proportion of vehicles traveling at 65 mph or more, (4) the proportion of vehicles
traveling at 70 mph or more, (5) the proportion of vehicles traveling at 75 mph or more,
(6) the proportion of vehicles traveling at 80 mph or more, and (7) the proportion of
vehicles traveling at 85 mph or more. [Please note that in addition, we derived the
following measures—(8) median speed, (9) 15th percentile, (10) 85th percentile, (11) 90th
percentile (12) 95th percentile, and (13) the total number of vehicles—though we did not
conduct statistical comparisons for the median speed or the percentile measures. We did
not conduct statistical analyses for these measures because the comparisons are not valid.
The speed data from which they are derived are collected in one 40-mph bin (from 0.01
mph to 40.00 mph), nine 5-mph bins (40.01 mph to 45.00 mph, 45.01 mph to 50.00 mph;
50.01 mph to 55.00 mph; 55.01 mph to 60.00 mph; 60.01 mph to 65.00 mph; 65.01 mph
to 70.00 mph; 70.01 mph to 75.00 mph; 75.01 mph to 80.00 mph; and 80.01 mph to
85.00 mph), and one 15-mph bin (from 85.01 mph to 100.00 mph) and no differentiation
within the bins is possible, which makes a statistical analysis invalid.]
To test for differences in the mean speeds we used the procedure for comparing
population means outlined by Kitchens (1987, p 369-373). For the comparisons
involving the percentage of vehicles in the 10 mph pace and proportions of vehicle
traveling at various speeds, we treated each distribution of speeds as a Bernoulli
population—i.e., a population in which each element is one of two possibilities, in this
case, (1) in or out of the 10 mph pace, or (2) above or below a selected speed (e.g., 75
mph). We then used the procedure for comparing population proportions described by
Kitchens (1987, pages 400-404). The statistical tests were conducted in two ways. First,
we conducted the tests in the traditional way, using n-values that were equal to the
number of vehicles that traveled by each ATRs in the test periods under consideration. In
the second, we used an extremely conservative correction, with n-values that were equal
to the number of hours in each test period—because it is likely that, when traffic is
congested, individual vehicles may travel at speeds which are not independent of each
other.
1.2 Organization of this Report
The next section of this report, Section 2, presents summary data. Then, detailed
analyses are presented in subsequent sections of the report. There is a section for each of
the four road types, with analyses of the speed data obtained at each of the ATRs listed in
Table 1.1. The final two sections of this report deal with crash data and citation data.
A4-5
Section 2: Summary of Findings during the Third MSMP Test Period
In the MSMP, we obtained speed data from 21 ATRs located throughout Minnesota.
Fourteen of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining seven were located Outside Enhanced Enforcement Zones. Seven ATRs were
located on 2-Lane 2-Way Highways, while five were located on 4-Lane Divided
Highways, five on Rural Freeways, and four on Urban Freeways. The effect of the
MSMP on the speed data obtained at these ATRs is summarized in this section of the
report.
2.1. Overall Effect of the MSMP during the Third Enhanced and Regular Enforcement
Periods
To provide a brief overall summary of the effect of the MSMP during the Third Test
Period on driving speeds, we focused on vehicles traveling at least 10 mph above the
speed limit at the locations of the ATRs Within the Enhanced Enforcement Zones during
the MSMP. [It should be noted that, on the 2-Lane/2-Way Highways and the Urban
Freeways, at the locations Within the Enhanced Enforcement Zones the speed limits were
increased from 55 mph to 60 mph, while at the locations Outside the Enhanced
Enforcement Zones the speed limits were unchanged at 55mph. Also, the speed limits
remained unchanged at 65 mph on 4-Lane Divided Highways and at 70 mph on Rural
Freeways.]
Table 2.1 shows the decrease or increase in the percentage of the vehicles traveling at
least 10 mph above the speed limit during the Third Enhanced Enforcement Period and
the Third Regular Enforcement Periods as compared to the percentages traveling at those
speeds before the MSMP was implemented. This means that, for the ATRs located on
the 2-Lane 2-Way Highways and the Urban Freeways, the percentages shown are for
vehicles traveling at 70 mph or more (10 mph above the new speed limit and 15 mph
above the pre-MSMP speed limit); while for the ATRs located on the 4-Lane Divided
Highways, the percentages shown are for vehicles traveling at 75 mph or more; and for
the ATRs located on the Rural Freeways, the percentages shown are for vehicles
traveling at 80 mph or more.
A4-6
Table 2.1: Summary of the Effect of the MSMP on the Percentage of Vehicles
Traveling at Least 10 mph Above the Speed Limits during the MSMP
Road type
2-Lane 2-Way
Highways
4-Lane Divided
Highways
Rural
Freeways
Urban
Freeways
Within the Enhanced Enforcement
Zones
Increase/
Increase/
Decrease during Decrease during
Third Regular
Third Enhanced
Enforcement
Enforcement
Period
Period
Outside the Enhanced Enforcement
Zones
Increase/
Increase/
Decrease during Decrease during
Third Regular
Third Enhanced
Enforcement
Enforcement
Period
Period
-41.28%
-26.79%
+53.33%
+56.71%
-38.52%
-60.90%
-34.73%*
-31.75%*
-61.78%
-51.80%
-73.08%*
-77.52%*
-13.50%**
-12.94%**
-10.16%*
-11.33%*
*Speed data from one ATR located close to Enhanced Enforcement Zones.
**Historical speed data used in comparisons obtained just before the start of the MSMP.
Table 2.1 shows that, for the all four highway types with ATRs located Within the
Enhanced Enforcement Zones, there were decreases in the percentages of vehicles
traveling at least 10 mph above the speed limits. The table also shows that, with one
exception, for the highways with ATRs located Outside the Enhanced Enforcement
Zones, there were also decreases in the percentage of vehicles traveling at least 10 mph
above the speed limits Within the Enhanced Enforcement Zones. The exception was for
the 2-Lane 2-Way Highways (for which there were four ATRs Outside the Enhanced
Enforcement Zones). It should be noted that for the other three road types, there was a
single ATR Outside the Enhanced Enforcement Zones—and that, in each case, the ATR
was located relatively close to one, or two, Enhanced Enforcement Zones.
The data from which Table 2.1 was derived for each of the four road types is presented in
more detail in the remainder of the section of the report.
2.2. Effect of the MSMP on 2-Lane 2-Way Highways
In the MSMP, we obtained speed data from seven ATRs located on 2-Lane 2-Way
Highways—three of these ATRs were located Within Enhanced Enforcement Zones,
while the remaining four were located Outside Enhanced Enforcement Zones. The speed
limit was increased from 55 mph to 60 mph at the locations of the three ATRs Within
Enhanced Enforcement Zones, while the speed limit remained unchanged at 55 mph at
the locations of the four ATRs Outside Enhanced Enforcement Zones.
In order to provide a brief overall summary of the effect of the MSMP, we focused on
drivers traveling at least 10 mph above the new speed limit. We combined the speed data
from the three ATRs Within Enhanced Enforcement Zones. Then, we compared speed
A4-7
data from the Test Year with data from the previous year—when the speed limit at the
locations of the three ATRs was still 55 mph. Table 2.2 shows the results of this
comparison for the Third Enhanced Enforcement Period.
Table 2.2: Effect of MSMP on 2-Lane 2-Way Highways during the Third Enhanced
Enforcement Period at Three ATRs Within Enhanced Enforcement Zones
Sample Total
312,288
Sample Total
290,973*
One Year Before MSMP
# Over 70 mph
18,093
Third Enhanced Enforcement Period
# Over 70 mph
9,889*
% Over 70 mph
5.79
% Over 70 mph
3.40*
Result: 41.28% Reduction in Drivers Traveling Over 70 mph
*Numbers adjusted to account for limited availability of speed data from ATR-210 (7 weeks) and ATR-219
(6 weeks) during the time period.
Table 2.2 indicates that, for the three ATRs Within Enhanced Enforcement Zones on 2Lane 2-Way Highways, during the Third Enhanced Enforcement Period, there was a
41.28% decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the
new speed limit.
A similar comparison was conducted for the Third Regular Enforcement Period. The
results of this comparison are shown in Table 2.3.
Table 2.3: Effect of the MSMP at Three ATRs Within Enhanced Enforcement
Zones on 2-Lane 2-Way Highways during the Third Regular Enforcement Period
Sample Total
174,513
Sample Total
164,709
One Year Before MSMP
# Over 70 mph
8541
Third Regular Enforcement Period
# Over 70 mph
5,889
% Over 70 mph
4.89
% Over 70 mph
3.58
Result: 26.79% Reduction in Drivers Traveling Over 70 mph
Table 2.3 shows that, for the three ATRs Within Enhanced Enforcement Zones on 2-Lane
2-Way Highways, during the Third Regular Enforcement Period, there was a 26.79%
reduction in the number of drivers traveling over 70 mph—i.e., 10 mph over the speed
limit.
We also examined the speed data obtained from the four ATRs Outside Enhanced
Enforcement Zones, where there was no change in the level of enforcement during the
A4-8
MSMP and no change in the speed limit. We compared this data with speed data from
the previous year. For comparison purposes, we focused on drivers traveling at 70 mph
or more—while this is 10 mph above the new speed limit Within Enhanced Enforcement
Zones, it is 15 mph above the actual speed limit at the locations of the four ATRs Outside
Enhanced Enforcement Zones. The results of this comparison for speed data obtained
during the Third Enhanced Enforcement Period are shown in Table 2.4.
Table 2.4: Effect of the MSMP at Four ATRs Outside Enhanced Enforcement
Zones on 2-Lane 2-Way Highways during the Third Enhanced Enforcement Period
Sample Total
373,303
Sample Total
379,657
One Year Before MSMP
# Over 70 mph
8,385
Third Enhanced Enforcement Period
# Over 70 mph
13,036
% Over 70 mph
2.25
% Over 70 mph
3.45
Result: 53.33% Increase in Drivers Traveling Over 70 mph
Table 2.4 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on 2-Lane 2-Way Highways, during the Third Enhanced Enforcement Period, there was a
53.33% increase in the number of drivers traveling over 70 mph—i.e., 10 mph above the
new speed limit Within Enhanced Enforcement Zones (and 15 mph above the current
speed limit Outside the Enhanced Enforcement Zones).
A similar comparison was conducted for the Third Regular Enforcement Period. The
results of this comparison using speed data from the four ATRs located Outside
Enhanced Enforcement Zones are shown in Table 2.5.
Table 2.5: Effect of the MSMP at Four ATRs Outside Enhanced Enforcement
Zones on 2-Lane 2-Way Highways during the Third Regular Enforcement Period
Sample Total
220,641
Sample Total
219,212
One Year Before MSMP
# Over 70 mph
5,104
Third Regular Enforcement Period
# Over 70 mph
7,937
% Over 70 mph
2.31
% Over 70 mph
3.62
Result: 56.71% Increase in Drivers Traveling over 70 mph
Table 2.5 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on the 2-Lane 2-Way Highways, during the Third Regular Enforcement Period there was
a 56.71% increase in the number of drivers traveling over 70 mph—i.e., at 10 mph over
A4-9
the new speed limit Within Enhanced Enforcement Zones (and 15 mph above the current
speed limit Outside Enhanced Enforcement Zones).
Comparisons between speed data from the ATRs located Within Enhanced Enforcement
Zones and the ATRs located Outside Enhanced Enforcement Zones should be treated
with caution. It should be noted that the three ATRs located Within Enhanced
Enforcement Zones are clustered close together in Northern Minnesota and that, for these
ATRs, the proportion of vehicles traveling at 70 mph or more ranges between 0.024 and
0.073. In contrast, the four ATRs located Outside Enhanced Enforcement Zones are
more widely spread; with three in South Western Minnesota, and one in East Central
Minnesota. For the four ATRs located Outside Enhanced Enforcement Zones, there is a
much greater range in the proportion of vehicles traveling at 70 mph or more: It varies
between 0.002 (in the Third Enhanced Enforcement Period) for ATR-179—one of the
three ATRs in South Western Minnesota—and 0.159 (also in the Third Enhanced
Enforcement Period) for ATR-222—which is located in East Central Minnesota.
2.3. Effect of the MSMP on 4-Lane Divided Highways
In the MSMP, we obtained speed data from five ATRs located on 4-Lane Divided
Highways. Four of these ATRs were located Within Enhanced Enforcement Zones, while
the remaining ATR was located Outside the Enhanced Enforcement Zones. At the
locations of the four ATRs Within the Enhanced Enforcement Zones and the ATRs
Outside the Enhanced Enforcement Zones, the speed limit was unchanged—at 65mph—
during the MSMP.
In order to provide a brief overall summary of the effect of the MSMP, we focused on
drivers traveling at least 10 mph above the speed limit—i.e., on drivers traveling at 75
mph or more speed data from the four ATRs Within Enhanced Enforcement Zones were
combined. Then, we compared speed data from the Test Year with data from previous
years—in the case of two of the ATRs (ATR-172 and ATR-188) the data are from one
year earlier, while the data for the remaining two ATRs (ATR-187 and ATR-197) are
from two years earlier. Table 2.6 shows the results of this comparison for the Third
Enhanced Enforcement Period.
A4-10
Table 2.6: Effect of the MSMP at Four ATRs Within Enhanced Enforcement Zones
on 4-Lane Divided Highways during the Third Enhanced Enforcement Period
Sample Total
3,538,008*
Sample Total
3,587,671
Pre-MSMP
# Over 75 mph
263,423*
Third Enhanced Enforcement Period
# Over 75 mph
164,420
% Over 75 mph
7.45*
% Over 75 mph
4.58
Result: 38.52% Reduction in Drivers Traveling Over 75 mph
*Data for ATR-172 and ATR-188 are from one year earlier; data for ATR-187 and 197are from two years
earlier.
Table 2.6 indicates that, for the four ATRs located Within Enhanced Enforcement Zones
on 4-Way Divided Highways, during the Third Enhanced Enforcement Period, there was
a 38.52% decrease in the number of drivers traveling over 75 mph—i.e., 10 mph over the
speed limit.
A similar comparison was conducted for the Third Regular Enforcement Period. Again,
the data for ATR-172 and ATR-188 are from one year earlier, the data for ATR-187 are
from two years earlier, and data for ATR-187 are from three years earlier. The results of
the comparison are shown in Table 2.7.
Table 2.7 Effect of the MSMP at Four ATRs Within Enhanced Enforcement Zones
on 4-Lane Divided Highways during Third Regular Enforcement Period
Sample Total
1,989,698*
Sample Total
1,981,277
Pre-MSMP
# Over 75 mph
141,520*
Third Regular Enforcement Period
# Over 75 mph
55,116
% Over 75 mph
7.11*
% Over 75 mph
2.78
Result: 60.90% Reduction in Drivers Traveling Over 75 mph
*Data for ATR-172 and ATR-188 are from one year earlier; data for ATR-187 and 197are from two years
earlier.
Table 2.7 shows that, for the ATRs Within Enhanced Enforcement Zones on 4-Way
Divided Highways, during the Third Regular Enforcement Period there was a 60.90%
reduction in the number of drivers traveling over 75 mph—i.e., 10 mph or more above
the speed limit.
We also examined the speed data obtained from the four ATRs Outside Enhanced
Enforcement Zones, where there was no change in the level of enforcement during the
MSMP and no change in the speed limit. We compared this data with speed data from
the previous year. For comparison purposes, we again focused on drivers traveling at 75
A4-11
mph or more—10 mph above the speed limit. The results of this comparison for speed
data obtained during the Third Enhanced Enforcement Period are shown in Table 2.8.
Table 2.8: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on a 4-Way Divided Highway During the Third Enhanced Enforcement Period
Sample Total
1,180,206
Sample Total
466,195
One Year Before MSMP
# Over 75 mph
56,500
Third Enhanced Enforcement Period
# Over 75 mph
14,528
% Over 75 mph
4.78
% Over 75 mph
3.12
Result: 34.73% Reduction in Drivers Traveling Over 75 mph
Table 2.8 shows that, for the single ATR located Outside the Enhanced Enforcement
Zones on a 4-Way Divided Highway, during the Third Enhanced Enforcement Period,
there was a 34.73% decrease in the number of drivers traveling over 75 mph—i.e., 10
mph or more above the speed limit.
A similar comparison was conducted for the Third Regular Enforcement Period. The
results of this comparison are shown in Table 2.9
Table 2.9: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on a 4-Way Divided Highway During the Third Regular Enforcement Period
Sample Total
636,670
Sample Total
640,029
One Year Before MSMP
# Over 75 mph
30,848
Third Regular Enforcement Period
# Over 75 mph
21,201
% Over 75 mph
4.85
% Over 75 mph
3.31
Result: 31.75% Reduction in Drivers over 75 mph
Table 2.9 shows that, for the ATR located Outside the Enhanced Enforcement Zones on a
4-Way Divided Highway, during the Third Regular Enforcement Period there was a
31.75% decrease in the number of drivers traveling over 75 mph—i.e., at 10 mph over
the speed limit.
Comparisons between speed data from the ATRs located Within Enhanced Enforcement
Zones and the ATR located Outside the Enhanced Enforcement Zones should be treated
with caution. The four ATRs located Within Enhanced Enforcement Zones are scattered
throughout Minnesota; while the single ATR Outside the Enhanced Enforcement Zones
is located a few miles to the South-West of the Twin Cities—and many of the drivers
A4-12
traveling past this ATR may have traveled through Enhanced Enforcement Zones in the
Cities.
2.4. Effect of the MSMP on Rural Freeways
In the MSMP, we obtained speed data from five ATRs located on Rural Freeways—four
of these ATRs were located Within Enhanced Enforcement Zones, while the remaining
ATR was located Outside the Enhanced Enforcement Zones. At the locations of all five
ATRs the speed limit remained unchanged at 70 mph.
In order to provide a brief overall summary of the effect of the MSMP, we compared this
data with speed data from the previous year, focusing on drivers traveling at least 10 mph
above the speed limit—i.e., those traveling at 80 mph or more. The speed data from the
ATRs Within Enhanced Enforcement Zones were combined. However in this case, the
speed data from the ATR-175 and ATR-227 were reliable; there were data collection
problems with one of the Southbound lanes for ATR-191, but we were able to use the
speed data collected in the Northbound lanes; and the speed data from the ATR-208 were
unreliable and had to be omitted. The data from ATR-175, ATR-191 (Northbound lanes
only), and ATR-227) were combined. Table 2.10 shows the results of the comparison for
the Third Enhanced Enforcement Period.
Table 2.10: Effect of MSMP on Rural Freeways during the Third Enhanced
Enforcement Period at Three ATRs (ATR-175, ATR-191, and ATR-227) Within
Enhanced Enforcement Zones
Sample Total
3,877,584
Sample Total
3,665,343*
One Year Before MSMP
# Over 80 mph
401,754
Third Enhanced Enforcement Period
# Over 80 mph
145,081*
% Over 80 mph
10.36
% Over 80 mph
3.96*
Result: 61.78% Reduction in Drivers over 80 mph
*Numbers adjusted to account for limited availability of data from ATR-191 (i.e., from the Northbound
lanes only) during the time period
Table 2.10 indicates that, for two of the ATRs Within Enhanced Enforcement Zones on
Rural Freeways, during the Third Enhanced Enforcement Period, there was a 61.78%
decrease in the number of drivers traveling at over 80 mph—i.e., 10 mph over the speed
limit—as compared to the same time period one year before the MSMP was
implemented.
A similar comparison was conducted for the Third Regular Enforcement Period. Again,
the speed data from ATR-175 and ATR-227 were reliable; while there were data
collection problems with one of the Southbound lanes for ATR-191 (although we were
A4-13
able to use the speed data collected in the Northbound lanes); and the speed data from the
ATR-208 were again unreliable and were omitted. The speed data from ATR-175, ATR191 (Northbound lanes only), and ATR-227) were combined. The results of this
comparison using speed data from the three ATRs are shown in Table 2.11.
Table 2.11: Effect of the MSMP at Three ATRs (ATR-175, ATR-191, and ATR227) Within Enhanced Enforcement Zones on Rural Freeways During the Third
Regular Enforcement Period
Sample Total
1,961,878
Sample Total
2,070,532*
One Year Before MSMP
# Over 80 mph
152,305
Third Regular Enforcement Period
# Over 80 mph
77,517*
% Over 80 mph
7.76
% Over 80 mph
3.74*
Result: 51.80% Reduction in Drivers over 80 mph
*Numbers adjusted to account for limited availability of data from ATR-191 (i.e., from the Northbound
lanes only) during the time period
Table 2.11 indicates that, for two of the ATRs located Within Enhanced Enforcement
Zones on Rural Freeways, during the Third Regular Enforcement Period, there was a
51.80% decrease in the number of drivers traveling over 80 mph—i.e., 10 mph over the
speed limit.
We also examined the difference between the speed data obtained during the Test Periods
from the ATR that was located Outside the Enhanced Enforcement Zones. We compared
this data with speed data from the previous year, focusing on drivers traveling at 80 mph
or more—10 mph above the speed limit. The results of this comparison for speed data
obtained during the Third Enhanced Enforcement Period are shown in Table 2.12.
Table 2.12: Effect of the MSMP on One ATR Outside the Enhanced Enforcement
Zones on a Rural Freeway During the Third Enhanced Enforcement Period
Pre-MSMP Speed Data from 4/24/05 to 5/21/05
# Over 80 mph
% Over 80 mph
182,044
15.08
Third Enhanced Enforcement Period
Sample Total
# Over 80 mph
% Over 80 mph
2,107,104
85,647
4.06
Sample Total
1,206,904
Result: 73.08% Reduction in Drivers Traveling over 80 mph
A4-14
Table 2.12 shows that, for the ATR located Outside Enhanced Enforcement Zones on a
Rural Freeway, during the Third Enhanced Enforcement Period, there was a 73.08%
decrease in the number of drivers traveling over 80 mph.
A similar comparison was conducted for the Third Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 2.13.
Table 2.13: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on a Rural Freeway During the Third Regular Enforcement Period
Sample Total
1,206,904
Sample Total
573,744
One Year Before MSMP
# Over 80 mph
182,044
Third Regular Enforcement Period
# Over 80 mph
19,477
% Over 80 mph
15.08
% Over 80 mph
3.39
Result: 77.52% Reduction in Drivers Traveling over 80 mph
Table 2.13 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
a Rural Freeway, during the Third Regular Enforcement Period there was a 77.52%
decrease in the number of drivers traveling over 80 mph, as compared to speed data
obtained between 4/24/05 and 5/21/05 before the MSMP was implemented.
For Rural Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
Zones should be treated with caution. The ATR Outside the Enhanced Enforcement
Zones is located between two Enhanced Enforcement Zones—one to the North-West; the
other to the South-East. It is likely that most drivers passing this ATR will have traveled
through one or other of these Enhanced Enforcement Zones. [It should also be noted that
there are no other ATRs Outside the Enhanced Enforcement Zones on Rural Freeways
that could have been considered for comparison purposes for this study.]
2.5. Effect of the MSMP on Urban Freeways
In the MSMP, we obtained speed data from four ATRs located on Urban Freeways—
three of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining ATR was located Outside the Enhanced Enforcement Zones. The speed limit
was increased from 55 mph to 60 mph at the locations of the three ATRs Within
Enhanced Enforcement Zones, while the speed limit remained unchanged at 55 mph at
location of the ATR Outside the Enhanced Enforcement Zones
In order to provide a brief overall summary of the effect of the MSMP, we focused on
drivers traveling at least 10 mph above the new speed limit. The speed data from the
A4-15
three ATRs Within Enhanced Enforcement Zones were combined. Then, we compared
speed data collected during the Third Enhanced Enforcement Period with pre-MSMP
speed data that were collected just before the Enhanced Enforcement began—these data
were collected two weeks during September 2005 for ATR-100, and four weeks during
August and September 2005 for ATR-I94 and ATR-35WCD. When the pre-MSMP data
were collected the speed limit at the locations of the three ATRs was still 55 mph. Table
2.14 shows the results of this comparison for the Third Enhanced Enforcement Period.
Table 2.14: Effect of the MSMP at Three ATRs Within Enhanced Enforcement
Zones on Urban Freeways during the Third Enhanced Enforcement Period
Sample Total
8,619,318*
Sample Total
17,022,271
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879*
Third Enhanced Enforcement Period
# Over 70 mph
1,866,292
% Over 70 mph
12.67*
% Over 70 mph
10.96
Result: 13.50% Reduction in Drivers over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-100 (for two weeks only—as
opposed to four weeks for both ATR-I94 and ATR-35WCD) during the pre-MSMP time period.
Table 2.14 indicates that, for the three ATRs Within Enhanced Enforcement Zones on
Urban Freeways, during the Third Enhanced Enforcement Period, there was a 13.50%
decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the new
speed limit—as compared to the month before the MSMP was implemented.
A similar comparison was conducted for the Third Regular Enforcement Period. The
results of this comparison using speed data from the three ATRs are shown in Table 2.15.
Table 2.15: Effect of the MSMP at Three ATRs Within Enhanced Enforcement
Zones on Urban Freeways during the Third Regular Enforcement Period
Sample Total
8,619,318*
Sample Total
8,883,499
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879*
Third Regular Enforcement Period
# Over 70 mph
979,890
% Over 70 mph
12.67*
% Over 70 mph
11.03
Result: 12.94% Reduction in Drivers over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-100 (for two weeks only—as
opposed to four weeks for both ATR-I94 and ATR-35WCD) during the pre-MSMP time period.
Table 2.15 indicates that, for the three ATRs located Within Enhanced Enforcement
Zones on Urban Freeways, during the Third Regular Enforcement Period, there was a
A4-16
12.94% decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the
new speed limit—as compared to the month before the MSMP was implemented.
We also examined the difference between the speed data obtained during the Test Periods
from the ATR that was located Outside the Enhanced Enforcement Zones. For this ATR
location there was no change in the level of enforcement during the MSMP and no
change in the speed limit. We compared the data obtained during the Test Periods with
speed data from the previous year. For comparison purposes, we focused on drivers
traveling at 70 mph or more—while this is 10 mph above the new speed limit Within
Enhanced Enforcement Zones, it is 15 mph above the actual speed limit at the location of
the ATR Outside Enhanced Enforcement Zones. The results of this comparison for speed
data obtained during the Third Enhanced Enforcement Period are shown in Table 2.16.
Table 2.16: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on an Urban Freeway during the Third Enhanced Enforcement Period
Sample Total
2,384,645
Sample Total
2,287,993
One Year Before MSMP
# Over 70 mph
1,463,568
Third Enhanced Enforcement Period
# Over70 mph
1,261,561
% Over 70 mph
61.37
% Over 70 mph
55.13
Result: 10.16% Reduction in Drivers Traveling over 70 mph
Table 2.16 shows that, for the ATR located Outside Enhanced Enforcement Zones on an
Urban freeway, during the Third Enhanced Enforcement Period, there was a 10.16%
decrease in the number of drivers traveling over 70 mph—i.e., 10 mph above the new
speed limit Within Enhanced Enforcement Zones (and 15 mph above the current speed
limit Outside the Enhanced Enforcement Zones).
A similar comparison was conducted for the Third Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 2.17.
Table 2.17: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on an Urban Freeway during the Third Regular Enforcement Period
Sample Total
1,262,150
Sample Total
1,228,470
One Year Before MSMP
# Over 70 mph
763,410
Third Regular Enforcement Period
# Over 70 mph
658,810
% Over 70 mph
60.48
% Over 70 mph
53.63
Result: 11.33 % Reduction in Drivers Traveling over 70 mph
A4-17
Table 2.17 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
an Urban Freeway, during the Third Regular Enforcement Period there was a 11.33%
decrease in the number of drivers traveling over 70 mph—i.e., at 10 mph or more above
the new speed limit Within Enhanced Enforcement Zones (and 15 mph or more above the
current speed limit Outside Enhanced Enforcement Zones).
For Urban Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
Zones should be treated with caution. It should be noted that the location of ATR that
was located Outside the Enhanced Enforcement Zones is only a few miles to the North of
an Enforced Enforcement Zone. And, most of the drivers traveling North past this ATR
will have traveled through that Enhanced Enforcement Zone. [It should also be noted
that, the locations of all the other ATRs Outside the Enhanced Enforcement Zones on
Urban Freeways that might have been considered for comparison purposes for this study
are also very close to Enhanced Enforcement Zones.]
2.6. Crash Rates During the First, Second, and Third MSMP Periods
During the First, Second, and Third MSMP Test Periods, crash data were available for all
Minnesota trunk highways. These trunk highways included 2-Lane/2-Way Highways, 4Lane Highways, Rural Freeways, and Urban Highways. Some of these highways had
changes in speed limits during the MSMP, some had enhanced enforcement during the
MSMP, and speed data were available from some of them. In all, there were twelve
combinations of Road Type, Speed Limits, and Enforcement Status. Table 2.18 lists the
Crash Rate, the Severity Rate, and the Fatal Crash Rate for each of these combinations
during the first 22 weeks of the MSMP.
A4-18
Table 2.18: Crash Rate, Severity Rate, and Fatal Crash Rate for Each Combination
of Trunk Highway Type, Speed Limits During the MSMP, and Enforcement Zone
During the First 34 Weeks of the MSMP
Within
Road Type/
Speed Limit
2 Lane/2-Way Highway
Increase—55 to 60 mph
2 Lane/2-Way Highway
No Change—55 mph
4 Lane/Divided Highway
No Change—65 mph
Rural Freeway
Unchanged—70 mph
Urban Freeway
Increase—55 to 60 mph
Urban Freeway
No Change—55 mph
Urban Freeway
No Change—60 mph
Outside
Crash
Rate
Severity
Rate
Fatal
Crash
Rate
Crash
Rate
Severity
Rate
Fatal
Crash
Rate
0.7839
1.2563
1.3401
0.5742
0.8677
0.9677
—
—
—
0.8415
1.2750
1.1981
0.6162
0.8885
0.4777
0.6787
0.9783
0.6837
0.7176
0.9959
0.5937
0.5999
0.8346
0.2419
0.9141
1.2283
0.2992
—
—
—
1.3767
1.7841
0.2911
1.4176
1.8078
0.4151
0.8049
1.0591
0.0000
0.9087
1.1811
0.0625
2.7. Citation Data During the Third Enhanced Enforcement Period
During the Third MSMP Enhanced Enforcement Period citation data were collected for
all the highways on which there was Enhanced Enforcement. These data are summarized
in Table 2.19. The table presents, for each of the four highway types in the MSMP, the
Number of Speed Citations and the Number of Speed Warnings that were given during
the Third Enhanced Enforcement Period, as well as the Number of Vehicles that were
Stopped and the Number of Hours of Enforcement.
Table 2.19: Citation Data for the Four Types of Highways on Which ATRs Were
Located During the Third Enhanced Enforcement Period
Type of
Highway
Number of
Speed Citations
Number of
Speed Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
377
1,488
2,053
1,128
2-Lane/2-Way
Highway
4-Lane
Divided
Highway
Rural Freeway
Urban
Freeway
598
957
1,084
1,325
1,876
2,532
960
976
2,676
1,622
4,775
1,747
Total
4,608
5,519
11,236
4,811
A4-19
Section 3. Speed Data Obtained on 2-Lane/2-Way Highways During the Third Test
Period
We obtained speed data from seven ATRs that were located on 2-Lane 2-Way Highways.
Three of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining four were located Outside Enhanced Enforcement Zones. During the MSMP,
at the locations of the three ATRs Within the Enhanced Enforcement Zones, the speed
limit was increased from 55 mph to 60 mph and there was Enhanced Enforcement at
various times. In contrast, at the locations of the four ATRs Outside the Enhanced
Enforcement Zones, the speed limit remained unchanged at 55 mph and there was no
change in the enforcement level during the MSMP.
In this section of the report, for the ATRs located Within Enhanced Enforcement Zones
and the ATRs located Outside Enhanced Enforcement Zones, we present comparisons of
the speed data obtained during the Third Test Period with the speed data obtained at those
same ATRs in the three years prior to the MSMP. Comparisons using the speed data
from the ATRs located Within Enhanced Enforcement Zones are presented first. Then,
we present comparisons using the speed data from the ATRs located Outside Enhanced
Enforcement Zones.
In making the comparisons between the speed data obtained during the Third Test Period
and the speed data obtained prior to the MSMP, we used two statistical tests. The first
test was used to examine differences in the mean speeds—for this we used the procedure
for comparing population means outlined by Kitchens (1987, p 369-373). The second
test was used to explore differences in the percentage of vehicles in the 10 mph pace and
in the differences in the proportions of vehicle traveling at various speeds. For this test,
we treated the distribution of speeds as a Bernoulli population—i.e., a population in
which each element is one of two possibilities, in this case, (1) in or out of the 10 mph
pace, or (2) above or below a selected speed (e.g., 75 mph). We then used the procedure
for comparing population proportions described by Kitchens (1987, pages 400-404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
ATR in the time periods under consideration. Second, the tests were conducted using an
extremely conservative correction, with n-values equal to the number of hours in each
test period —the rationale for this was that it is possible, when traffic is congested, that
individual vehicles may travel at speeds which are not independent of each other.
3.1. Speed Data from ATRs located Within Enhanced Enforcement Zones
The three ATRs located Within Enhanced Enforcement Zones on 2-Lane 2-Way
Highways were as follows: (1) ATR-210, on US-71, near Blackduck in Beltrami County,
(2) ATR-219, on US-2, near Warba in Itasca County, and (3) ATR-220, on US-71, South
A4-20
of CR 89 in Hubbard County. At the locations of all three of these ATRs, the speed limit
was increased from 55 mph to 60 mph during the MSMP. The effect of the MSMP on
the speed data at each of these three ATRs during the Third Test Period is reported in this
section. It is reported ATR by ATR—with the effect of the MSMP in the Third
Enhanced Enforcement Period followed by its effect in the Third Regular Enhancement
Period.
For each of the three ATRs Within Enhanced Enforcement Zones, two tables are
presented for each time period. In the first of these tables speed data from the Test Year
are compared with the available historical speed data. Where possible speed data from
the three years prior to the MSMP are included in this table—however, in some cases
data are only available from one or two of the prior years. Also in some cases, speed data
are not available from the whole of the eight-week Enhanced Enforcement Period or the
whole of the four-week Regular Enhancement Period—in these cases the dates from
which the data are available are noted in the table. In the second of the two tables for
each ATR, the focus is on drivers traveling at least 5 mph and at least 10 mph above the
new speed limit adopted for the MSMP—i.e., on drivers traveling at 65 mph or more and
at 70 mph or more. In this second table, we present the number (and proportion) of
vehicles traveling above these speeds throughout the eight-week Enhanced Enforcement
Period or the four-week Regular Enhancement Period. We also present the average
number of vehicles traveling above these speeds every day. Then, the table presents the
decrease in the number of vehicles relative to the number that were traveling at these
speeds before the MSMP. It should be noted that, in each of three years before the
MSMP was adopted, these speeds (of 65 mph or more and 70 mph or more) were 10 mph
and 15 mph above the pre-MSMP speed limit.
A4-21
ATR-210—Enhanced Enforcement Period #3
Table 3.1 (a): ATR-210—Speed Data from Enhanced Enforcement Period #3
Compared with Speed Data from Three Previous Years
Decrease/Increase
as Compared to
One Year Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
(All Eight Weeks)
(All Eight Weeks)
Decrease/
Increase as
Compared to
Three Years
Earlier
(Four Weeks
Only 2/27/03 to
3/26/03)
Measure
Test Period
(Seven Weeks
Only 3/6/06 to
4/23/06)
Mean (mph)
60.31135055
-0.80124**
+0.409446**
-0.518303**
Percent in 10
mph pace
68.8337683
+8.03477**
+7.44301**
+8.43764**
0.177654726
-0.064965**
-0.025836*
-0.065066**
0.046517672
-0.032067**
-0.014806*
-0.026057**
0.012653926
-0.012263**
-0.006932*
-0.010772*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.003398369
-0.003618*
-0.0018043*
-0.002914*
0.001399328
-0.001498*
ns
-0.000644*
Vehicle Total
50,024
59,719
59,585
27,406
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.1 (b): ATR-210—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Seven
Weeks Only
3/6/06 to
4/23/06)
7.29560*
60.83139445
55.43636248
66.05442073
67.96082317
69.86722561
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-22
Table 3.2 (a): ATR-210—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
ph) During Enhanced Enforcement Period #3 and During the Previous Three Years
Measure
Number of vehicles at
60 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(Seven
Weeks Only
3/6/06 to
4/23/06)
Daily
Average
in Test
Period
8,887
181
-66
-26
-66
2,327
47
-33
-15
-27
50,024
1,021
—
—
—
Table 3.2 (b): ATR-210—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #3 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.177655
0.177655
-0.064965
-0.025836
-0.065066
0.046518
0.046518
-0.032067
-0.014806
-0.026057
50,024
1,021
—
—
—
Test Period
(Seven
Weeks
Only 3/6/06
to 4/23/06)
A4-23
ATR-210—Regular Enforcement Period #3
Table 3.3 (a): ATR-210—Speed Data from Regular Enforcement Period #3
Compared with Speed Data from Three Previous Years
Measure
Test Period
(4/24/06 to
5/21/06)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
60.56635
-0.57352**
+0.291188**
-0.39237**
Percent in 10
mph pace
67.8141
+5.7119**
+5.3133
+5.5382**
0.187900
-0.048747**
-0.025246*
-0.042832*
0.053534
-0.019537*
-0.014089*
-0.019777*
0.014627
-0.007315*
-0.005051*
-0.008957*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.003483
-0.002178*
-0.001932*
-0.002444*
0.001493
ns
-0.000953*
-0.000884*
Vehicle Total
30,149
32,859
34,352
33,242
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.3 (b): ATR-210—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
7.271073*
61.03176
55.57986
66.41033
68.27092
70.45418
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-24
Table 3.4 (a): ATR-210—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #3 and During the Previous Three Years
Measure
Number of vehicles at
60 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
5,665
202
-53
-27
-46
1,614
57
-21
-15
-21
30,149
1,077
—
—
—
Table 3.4 (b): ATR-210—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #3 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.187900
0.187900
-0.048747
-0.025246
-0.042832
0.053534
0.053534
-0.019537
-0.014089
-0.019777
30,149
1,077
—
—
—
A4-25
ATR-219—Enhanced Enforcement Period #3
Table 3.5 (a): ATR-219—Speed Data from Enhanced Enforcement Period #3
Compared with Speed Data from the Two Previous Years
Measure
Test Period
(Six Weeks
Only
3/13/06 to
4/23/06)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Mean (mph)
61.9228363
+0.19974**
+0.150038**
Percent in 10
mph pace
79.678295
+8.4361**
+6.08801**
0.14342795
-0.048605**
-0.031578**
0.02479353
-0.021655**
-0.013502*
0.00616171
-0.00589*
-0.003192*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.00177775
-0.00120*
-0.000517*
0.00056957
-0.000283*
ns
Vehicle Total
115,877
167,820
169,994
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.5 (b): ATR-219—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Six Weeks
Only
3/13/06 to
4/23/06)
4.81247*
62.1717479
58.0587789
64.9478719
66.8303266
68.9376409
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-26
Table 3.6 (a): ATR-219—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #3 and the Previous Two Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
16,620
396
-134
-87
2,873
68
-60
-37
115,877
2,759
—
—
Test Period
(Six Weeks
Only
3/13/06 to
4/23/06)
Table 3.6 (b): ATR-219—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #3 the Previous Two Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
-0.048605
-0.031578
0.024794
0.143428
68
0.024794
-0.021655
-0.013502
115,877
2,759
—
—
Test Period
(Six Weeks
Only
3/13/06 to
4/23/06)
0.143428
Daily
Average
in Test
Period
A4-27
ATR-219—Regular Enforcement Period #3
Table 3.7: ATR-219—Comparison of Speed Data from Regular Enforcement Period
#3 Compared with Speed Data from Two Earlier Years
Measure
Test Period
(4/24/06 to
5/21/06)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
62.00485
+0.233198
+0.19723
Percent in 10
mph pace
78.9790
+2.9925*
+10.5185**
0.152118
-0.007329*
-0.063930**
0.027343
-0.008506*
-0.025159**
0.006753
-0.002129*
-0.007301*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.00182
-0.000689*
-0.0013790*
0.000595
ns
-0.000454*
Vehicle Total
87,373
90,074
95,349
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.7 (b): ATR-219—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
4.80129*
62.21158
58.08648
65.08487
67.08847
69.09207
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-28
Table 3.8 (a): ATR-219—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #3 and the Previous Two Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test
Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
13,291
475
-23
-199
2,389
85
-27
-78
87,373
3,120
—
—
Table 3.8 (b): ATR-219—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #3 the Previous Two Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.152118
0.152118
-0.007329
-0.063930
0.027343
0.027343
-0.008506
-0.025159
87,373
3,120
—
—
A4-29
ATR-220—Enhanced Enforcement Period #3
Table 3.9 (a): ATR-220—Speed Data from Enhanced Enforcement Period #3
Compared with Speed Data from One Year Earlier
Measure
Test Period
(2/27/06 to 4/23/06)
Decrease/Increase as
Compared to One Year
Earlier
Mean (mph)
61.239029
-0.67082**
Percent in 10 mph pace
73.8378812
4.3319**
0.164501892
-0.046332**
0.042862547
-0.023274**
0.010138714
-0.006652*
0.003102144
-0.002373*
0.000970996
-0.000976*
79,300
84,749
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.9 (b): ATR-220—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
6.40801*
61.67562164
56.65898081
65.59610201
67.65135808
69.70661414
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-30
Table 3.10 (a): 220—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #3 and One Year Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(2/27/06 to
4/23/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
13,045
233
-66
3,399
61
-33
79,300
1,416
—
Table 3.10 (b): 220—Comparison of the Proportion of Vehicles Traveling at Least 5
mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #3 and One Year Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(2/27/06 to
4/23/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.164502
0.164502
-0.046332
0.042863
0.042863
0.023274
79,300
1,416
—
A4-31
ATR-220—Regular Enforcement Period #3
Table 3.11 (a): ATR-220—Comparison of Speed Data from Regular Enforcement
Period #3 with Speed Data from One Year Earlier
Measure
Test Period
(4/24/06 to 5/21/06)
Decrease/Increase as
Compared to One Year
Earlier
Mean (mph)
61.16436
-0.49702**
Percent in 10 mph pace
74.2116
+3.1228
0.158857
-0.033422*
0.039969
-0.016359*
0.008858
-0.005306*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.002776
-0.001655*
0.001017
ns
Vehicle Total
47,187
51,580
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.11 (b): ATR-220—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
6.20024*
61.54338
56.56859
65.3725
67.47531
69.57812
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-32
Table 3.12 (a): 220—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #3 and One Year Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(4/24/06 to
5/21/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
7,496
268
-56
1,886
67
-28
47,187
1,685
—
Table 3.12 (b): 220—Comparison of the Proportion of Vehicles Traveling at Least 5
mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During Regular
Enforcement Period #3 and One Year Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(4/24/06 to
5/21/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.158857
0.158857
-0.033422
0.039969
0.039969
-0.016359
47,187
1,685
—
A4-33
3.2. Speed Data from ATRs located Outside Enhanced Enforcement Zones
There were four ATRs located Outside Enhanced Enforcement Zones on 2-Lane 2-Way
Highways. These ATRs were as follows—(1) ATR-179, on USTH 59, near Garvin, in
Lyon County, (2) ATR-198, on USTH 212, East of TH 23, in Chippewa County, (3)
ATR-199, on USTH 75, North of CR 69, in Pipestone County, and ATR-222, on MNTH
65, near Pliny, in Aitkin County. During the MSMP, at the locations of the ATRs located
Outside Enhanced Enforcement Zones, speed limits remained unchanged—at 55 mph—
and there were no changes in enforcement. For each of these ATRs, the speed data
obtained during 2005, when the MSMP occurred, was compared with the historical speed
data. These comparisons are reported site by site, first for the eight-week time period
between 2/27 and 4/23, when the Third Enhanced Enforcement Period occurred during
the MSMP, and then for the four-week time period between 4/24 and 5/21, when the
Third Regular Enhancement Period occurred during the MSMP.
For each of the four ATRs located Outside Enhanced Enforcement Zones (as for the
ATRs located Within Enhanced Enforcement Zones), two tables are presented for each
time period. In the first table, speed data from the Test Year is compared with the
historical speed data. We include speed data from the three years prior to the MSMP in
the table, whenever possible—it should be noted that in some cases data are only
available from one or two prior years. Also in some cases, speed data are not available
from the whole of the eight-week Enhanced Enforcement Period or the four-week
Regular Enhancement Period—in these cases the dates from which the data are available
are noted in the table. In the second of the two tables for each of the ATRs located
Outside Enhanced Enforcement Zones, the focus is on drivers traveling at least 5 mph
and at least 10 mph above the new speed limit adopted for the MSMP—i.e., drivers
traveling at least 65 mph and at least 70 mph). It should be noted that during the MSMP,
as well as during the three years before it was adopted, these speeds (of at least 65 mph
and at least 70 mph) were 10 mph and 15 mph above the actual speed limit at the
locations of the four ATRs located Outside Enhanced Enforcement Zones. In this second
table, we present the number and proportion of vehicles traveling above these speeds
throughout the Third Enhanced Enforcement Period or the Third Regular Enhancement
Period. We also present the average number of vehicles traveling above these speeds
every day. Then, the table presents the decrease in the number of vehicles relative to the
number that were traveling at these speeds before the Test Year.
A4-34
ATR-179—Enhanced Enforcement Period #3
Table 3.13 (a): ATR-179—Comparison of Speed Data from Enhanced Enforcement
Period #3 with Speed Data from One Year Earlier
Measure
Test Period
(2/27/06 to 4/23/06)
Decrease/Increase as
Compared to One Year
Earlier
Mean (mph)
54.75669623
-0.91381**
Percent in 10 mph pace
68.0049226
+1.2277*
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
0.012147272
0.002033504
0.00043895
0.000161247
0.000026874
-0.006399*
-0.001197*
-0.000353*
-0.0001537*
-0.0000631*
Vehicle Total
111,630
111,128
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.13 (b): ATR-179—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
7.341907*
55.82089049
50.20474854
60.54988433
62.16396761
63.7780509
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-35
Table 3.14 (a): 179—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #3 and the Previous Year
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(2/27/06 to
4/23/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
1,356
24
-13
227
4
-2
111,630
1,993
—
Table 3.14 (b): 179—Comparison of the Proportion of Vehicles Traveling at Least 5
mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #3 and the Previous Year
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(2/27/06 to
4/23/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.012147
0.012147
-0.006399
0.002034
0.002034
-0.001197
111,630
1,993
—
A4-36
ATR-179—Regular Enforcement Period #3
Table 3.15 (a): ATR-179—Comparison of Speed Data from Regular Enforcement
Period #3 with Speed Data from One Year Earlier
Measure
Test Period
(4/24/06 to 5/21/06)
Decrease/Increase as
Compared to One Year
Earlier
Mean (mph)
55.39463
-0.45379762**
Percent in 10 mph pace
69.4535
+2.04443*
0.013991
-0.00370295*
0.002406
ns (-0.0003567)
0.0005932
ns
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.0001647
ns
0.000065915
ns
Vehicle Total
60,684
62,622
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.15 (b): ATR-220—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
6.61553*
56.17571
50.65157
60.99534
62.46754
63.93974
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-37
Table 3.16 (a): 179—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #3 and the Previous Year
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(4/24/06 to
5/21/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
849
30
-8
146
5
-1
60,684
2,167
—
Table 3.16 (b): 179—Comparison of the Proportion of Vehicles Traveling at Least 5
mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During Regular
Enforcement Period #3 and the Previous Year
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(4/24/06 to
5/21/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.013991
0.013991
-0.003703
0.002406
0.002406
-0.000357
60,684
2,167
—
A4-38
ATR-198—Enhanced Enforcement Period #3
Table 3.17 (a): ATR-198—Comparison of Speed Data from Enhanced Enforcement
Period #3 with Speed Data from One Year Earlier
Measure
Test Period
(2/27/06 to
4/23/06)
Decrease/Increase as
Compared to One Year
Earlier
Mean (mph)
56.8285558
-1.15765**
Percent in 10 mph pace
56.695321
-6.3338**
0.05425272
-0.013488*
0.0096904
-0.004457*
0.00180567
-0.001676*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.00067712
-0.000893*
0.00020314
ns
Vehicle Total
132,915
126,098
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.17 (b): ATR-179—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
9.40250*
58.6953578
51.4999829
63.6295525
64.3452112
65.4771653
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-39
Table 3.18 (a): 198—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #3 and the Previous Year
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(2/27/06 to
4/23/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
7,211
129
-32
1,288
23
-11
132,915
2,373
—
Table 3.18 (b): 198—Comparison of the Proportion of Vehicles Traveling at Least 5
mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #3 and the Previous Year
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(2/27/06 to
4/23/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.054253
0.054253
-0.013488
0.009690
0.009690
-0.004457
132,915
2,373
—
A4-40
ATR-198—Regular Enforcement Period #3
Table 3.19 (a): ATR-198—Comparison of Speed Data from Regular Enforcement
Period #3 with Speed Data from Three Previous Years
Measure
Test Period
(4/24/06 to
5/21/06)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease
/Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
(Two Weeks
Only)
Mean (mph)
57.32868
-0.34056**
-1.03947**
-1.02798**
Percent in 10 mph
pace
59.0073
-1.3151*
-8.6441**
-5.0039
0.061815
-0.004618*
-0.007444*
-0.020543*
0.011440
-0.002097*
-0.003324*
-0.005557*
0.002083
-0.000534*
-0.000766*
-0.001263*
0.0005910
ns
ns
-0.000664*
0.00019700
ns
ns
ns
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
71,067
70,327
74,777
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
33,476
Table 3.19 (b): ATR-198—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
8.88854*
58.95573
52.11831
63.78291
64.47299
66.1727
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-41
Table 3.20 (a): ATR-198—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
ph) During Regular Enforcement Period #3 and During the Previous Three Years
Measure
Number of vehicles at
60 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
4,393
813
157
-12
-19
-52
29
-5
-8
-14
71,067
2,538
—
—
—
Table 3.20 (b): ATR-198—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #3 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.061815
0.061815
-0.004618
-0.007444
-0.020543
0.011440
0.011440
-0.002097
-0.003324
-0.005557
71,067
2,538
—
—
—
A4-42
ATR-199—Enhanced Enforcement Period #3
Table 3.21 (a): ATR-199—Comparison of Speed Data from Enhanced Enforcement
Period #3 with Speed Data from Three Previous Years
Measure
Test Period
(2/27/06 to
4/23/06)
Decrease/
Increase as
compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
(Four Weeks
Only)
Mean (mph)
58.5226348
-0.754997**
+0.222018**
-0.252153**
Percent in 10
mph pace
70.669092
-3.0533*
+1.5711*
ns (+0.022019)
0.06838842
-0.021865**
-0.010525*
-0.020598**
0.01987823
-0.005393*
-0.004819*
-0.009441**
0.00530273
-0.001029*
-0.003652*
-0.004157**
0.00200606
ns
-0.000554*
-0.000932**
0.00081365
ns
-0.000406*
-0.000597**
71,284
70,435
73,815
34,039
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.21 (b): ATR-199—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
6.47393*
58.7668381
54.3707892
63.7324938
64.5090418
66.8953152
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-43
Table 3.22 (a): ATR-199—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
ph) During Enhanced Enforcement Period #3 and During the Previous Three Years
Measure
Number of vehicles at
60 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
4,875
87
-28
-13
-26
1,417
25
-7
-6
-12
71,284
1,273
—
—
—
Table 3.22 (b): ATR-199—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #3 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.068388
0.068388
-0.021865
-0.010525
-0.020598
0.019878
0.019878
-0.005393
-0.004819
-0.009441
71,284
1,273
—
—
—
A4-44
ATR-199—Regular Enforcement Period #3
Table 3.23 (a): ATR-199—Comparison of Speed Data from Regular Enforcement
Period #3 with Speed Data from Three Previous Years
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Measure
Test Period
(4/24/06 to 5/21/06)
Decrease/
Increase as
Compared to
One Year
Earlier
Mean (mph)
58.52449
-0.12009**
+0.132368**
-0.15351**
Percent in 10
mph pace
70.9642
ns (+0.2802)
+0.020921*
+1.2936*
0.068360
-0.012164*
-0.016678*
-0.023653**
0.019872
-0.003797*
-0.005402*
-0.007943*
0.004773
-0.001313*
-0.003880*
-0.005282*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.001802
ns
-0.001155*
-0.001558*
0.00065754
ns
-0.000760*
-0.000830*
Vehicle Total
41,062
41,404
49,911
41,688
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.23 (b): ATR-199—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
6.41869*
58.73061
54.39666
63.715
64.50199
66.89327
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-45
Table 3.24 (a): ATR-199—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
ph) During Regular Enforcement Period #3 and During the Previous Three Years
Measure
Number of vehicles at
60 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
2,807
100
-18
-24
-35
816
29
-6
-8
-12
41,062
1,467
—
—
—
Table 3.24 (b): ATR-199—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #3 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.068360
0.068360
-0.012164
-0.016678
-0.023653
0.019872
0.019872
-0.003797
-0.005402
-0.007943
41,062
1,467
—
—
—
A4-46
ATR-222—Enhanced Enforcement Period #3
Table 3.25 (a): ATR-222—Comparison of Speed Data from Enhanced Enforcement
Period #3 with Speed Data from Three Previous Years
Measure
Test Period
(2/27/06 to
4/23/06)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
(Four Weeks
Only)
Mean (mph)
62.52882747
+1.005755**
+0.684985**
+0.752101**
Percent in 10
mph pace
51.8953034
-12.2713**
-10.9096**
-10.71647**
0.363320173
+0.121813**
+0.099653**
+0.106153*
0.159240459
+0.091266**
+0.085089**
+0.074442*
0.061368052
+0.039263**
+0.037632**
+0.035788*
0.019113869
+0.013127**
+0.012589**
+0.012711*
0.008287899
+0.006216**
+0.005769**
ns
63,828
65,642
63,190
31,392
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.25 (b): ATR-222—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
9.85201*
62.72005018
56.01742323
70.47206659
73.02641268
76.34519837
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-47
Table 3.26 (a): ATR-222—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
ph) During Enhanced Enforcement Period #3 and During the Previous Three Years
Measure
Number of vehicles at
60 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
23,190
414
+139
+114
+121
10,164
182
+104
+97
+85
63,828
1,140
—
—
—
Table 3.26 (b): ATR-222—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #3 and During the Previous Three Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.363320
0.363320
+0.121813
+0.099653
+0.106153
0.159240
0.159240
+0.091266
+0.085089
+0.074442
63,828
1,140
—
—
—
A4-48
ATR-222—Regular Enforcement Period #3
Table 3.27 (a): ATR-222—Comparison of Speed Data from Regular Enforcement
Period #3 with Speed Data from the Two Previous Years
Measure
Test Period
(4/24/06 to
5/21/06)
Decrease/
Increase as
Compared to One
Year Earlier
Decrease/
Increase as
Compared to Two
Years Earlier
Mean (mph)
61.51005
-0.56338**
-0.80698**
Percent in 10
mph pace
53.2191
-13.089**
-12.304**
0.319964
+0.069013**
+0.046503*
0.132805
+0.068015**
+0.064807**
0.049031
+0.028918**
+0.026311**
0.014268
+0.009558*
+0.00824*
0.005905
+0.004199*
+0.003556*
46,399
46,288
48,943
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.27 (b): ATR-222—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
10.1124*
61.8879
55.49219
69.54062
71.95794
74.94218
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-49
Table 3.28 (a): ATR-222—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #3 and the Previous Two Years
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test
Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
14,846
530
+114
+77
6,162
220
+113
+107
46,399
1,657
—
—
Table 3.28 (b): ATR-222—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #3 the Previous Two Years
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.319964
0.319964
+0.069013
0.132805
0.132805
+0.068015
+0.046503
+107
+0.064807
46,399
1,657
—
—
3.3. Overall Effect of the MSMP on 2-Lane 2-Way Highways
In the MSMP, we obtained speed data from seven ATRs located on 2-Lane 2-Way
Highways—three of these ATRs were located Within Enhanced Enforcement Zones,
while the remaining four were located Outside Enhanced Enforcement Zones. The speed
limit was increased from 55 mph to 60 mph at the locations of the three ATRs Within
Enhanced Enforcement Zones, while the speed limit remained unchanged at 55 mph at
the locations of the four ATRs Outside Enhanced Enforcement Zones.
In order to provide a brief overall summary of the effect of the MSMP, we focused on
drivers traveling at least 10 mph above the new speed limit. Speed data from the three
ATRs Within Enhanced Enforcement Zones were combined. Then, we compared speed
data from the Test Year with data from the previous year, when the speed limit at the
A4-50
locations of the three ATRs was still 55 mph. Table 3.29 shows the results of this
comparison for the Third Enhanced Enforcement Period.
Table 3.29: Effect of MSMP on 2-Lane 2-Way Highways during the Third
Enhanced Enforcement Period at Three ATRs Within Enhanced Enforcement Zones
Sample Total
312,288
Sample Total
290,973*
One Year Before MSMP
# Over 70 mph
18,093
Third Enhanced Enforcement Period
# Over 70 mph
9,889*
% Over 70 mph
5.79
% Over 70 mph
3.40*
Result: 41.28% Reduction in Drivers Traveling Over 70 mph
*Numbers adjusted to account for limited availability of speed data from ATR-210 (7 weeks) and ATR-219
(6 weeks) during the time period.
Table 3.29 indicates that, for the three ATRs Within Enhanced Enforcement Zones on 2Lane 2-Way Highways, during the Third Enhanced Enforcement Period, there was a
41.28% decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the
new speed limit.
A similar comparison was conducted for the Third Regular Enforcement Period. The
results of this comparison are shown in Table 3.30.
Table 3.30: Effect of MSMP on 2-Lane 2-Way Highways during Third Regular
Enforcement Period at Three ATRs Within Enhanced Enforcement Zones
Sample Total
174,513
Sample Total
164,709
One Year Before MSMP
# Over 70 mph
8541
Third Regular Enforcement Period
# Over 70 mph
5,889
% Over 70 mph
4.89
% Over 70 mph
3.58
Result: 26.79% Reduction in Drivers Traveling Over 70 mph
Table 3.30 shows that, for the three ATRs Within Enhanced Enforcement Zones on 2Lane 2-Way Highways, during the Third Regular Enforcement Period, there was a
26.79% reduction in the number of drivers traveling over 70 mph—i.e., 10 mph over the
speed limit.
We also examined the difference between the speed data obtained during the Test Periods
from the four ATRs Outside Enhanced Enforcement Zones, where there was no change
in the level of enforcement during the MSMP and no change in the speed limit. For
A4-51
comparison purposes, we again focused on drivers traveling at 70 mph or more—while
this is 10 mph above the new speed limit Within Enhanced Enforcement Zones, it is 15
mph above the actual speed limit at the locations of the four ATRs Outside Enhanced
Enforcement Zones. The results of this comparison for speed data obtained during the
Third Enhanced Enforcement Period are shown in Table 3.31.
Table 3.31: Effect of MSMP on 2-Lane 2-Way Highways during the Third
Enhanced Enforcement Period at Four ATRs Outside Enhanced Enforcement Zones
Sample Total
373,303
Sample Total
379,657
One Year Before MSMP
# Over 70 mph
8,385
Third Enhanced Enforcement Period
# Over 70 mph
13,036
% Over 70 mph
2.25
% Over 70 mph
3.45
Result: 53.33% Increase in Drivers Traveling Over 70 mph
Table 3.31 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on 2-Lane 2-Way Highways, during the Third Enhanced Enforcement Period, there was a
53.33% increase in the number of drivers traveling over 70 mph—i.e., 10 mph above the
new speed limit Within Enhanced Enforcement Zones (and 15 mph above the current
speed limit Outside the Enhanced Enforcement Zones).
A similar comparison was conducted for the Third Regular Enforcement Period. The
results of this comparison using speed data from the four ATRs located Outside
Enhanced Enforcement Zones are shown in Table 3.32.
Table 3.32: Effect of MSMP on 2-Lane 2-Way Highways during Third Regular
Enforcement Period at Four ATRs Outside Enhanced Enforcement Zones
Sample Total
220,641
Sample Total
219,212
One Year Before MSMP
# Over 70 mph
5,104
Third Regular Enforcement Period
# Over 70 mph
7,937
% Over 70 mph
2.31
% Over 70 mph
3.62
Result—56.71% Increase in Drivers over 70 mph
Table 3.32 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on the 2-Lane 2-Way Highways, during the Third Regular Enforcement Period there was
a 56.71 increase in the number of drivers traveling over 70 mph—i.e., at 10 mph over the
new speed limit Within Enhanced Enforcement Zones (and 15 mph above the current
speed limit Outside Enhanced Enforcement Zones).
A4-52
Comparisons between speed data from the ATRs located Within Enhanced Enforcement
Zones and the ATRs located Outside Enhanced Enforcement Zones should be treated
with caution. It should be noted that the three ATRs located Within Enhanced
Enforcement Zones are all in Northern Minnesota, and that the proportion of vehicles
traveling at 70 mph or more ranges between 0.024 and 0.073 for these ATRs. In contrast,
the four ATRs located Outside Enhanced Enforcement Zones are more widely spread,
with three in South Western Minnesota and one in East Central Minnesota. For these
four ATRs, the there is a much greater range in the proportion of vehicles traveling at 70
mph or more; the proportion varies between 0.002 (in the Third Enhanced Enforcement
Period) for ATR-179—one of the three ATRs in South Western Minnesota—and 0.159
(also in the Third Enhanced Enforcement Period) for ATR-222—which is located in East
Central Minnesota.
A4-53
Section 4. Speed Data Obtained on 4-Lane Divided Highways
We obtained speed data from five ATRs that were located on 4-Lane Divided Highways.
Four of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining ATR was located Outside the Enhanced Enforcement Zones. At the locations
of the four ATRs Within the Enhanced Enforcement Zones and the ATRs Outside the
Enhanced Enforcement Zones, the speed limit was unchanged—remaining at 65mph—
during the MSMP.
For the ATRs located Within Enhanced Enforcement Zones and the ATR located Outside
Enhanced Enforcement Zones on 4-Lane Divided Highways, we present comparisons of
the speed data obtained during the Test Year with the speed data obtained at those same
ATRs in the three years prior to the MSMP. Comparisons using the speed data from the
ATRs located Within Enhanced Enforcement Zones are presented first. Then, we present
comparisons using the speed data from the ATR located Outside the Enhanced
Enforcement Zones.
In making the comparisons between the speed data obtained during the Test Year and the
speed data obtained prior to the MSMP, we used two statistical tests. The first test was
used to examine differences in the mean speeds—for this we used the procedure for
comparing population means outlined by Kitchens (1987, p 369-373). The second test
was used to explore differences in the percentage of vehicles in the 10 mph pace and in
the differences in the proportions of vehicle traveling at various speeds. For this test, we
treated the distribution of speeds as a Bernoulli population—i.e., a population in which
each element is one of two possibilities, in this case, (1) in or out of the 10 mph pace, or
(2) above or below a selected speed (e.g., 75 mph). We then used the procedure for
comparing population proportions described by Kitchens (1987, pages 400-404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
ATR in the time periods under consideration. Second, the tests were conducted using an
extremely conservative correction, with n-values equal to the number of hours in each
test period—the rationale for this was that it is possible, when traffic is congested, that
individual vehicles may travel at speeds which are not independent of each other.
4.1. Speed Data from the ATRs located Within Enhanced Enforcement Zones
The four ATRs located Within Enhanced Enforcement Zones on 4-Lane Divided
Highways were as follows; (1) ATR-172,on US-10, near Dilworth, in Clay County, (2)
ATR-187, on US-10, near Rice, in Benton County, (3) ATR-188, on US-52, North of
Rochester, in Olmstead County, and (4) ATR-197, on SR-60, West of SR-4, in
Watonwan County. At these four sites, the speed limit remained unchanged at 65 mph.
The effect of the MSMP on the speed data at each of these four ATRs is reported in this
section. It is reported ATR by ATR—with the effect of the MSMP in the Third
A4-54
Enhanced Enforcement Period followed by its effect in the Third Regular Enhancement
Period.
For each of the four ATRs Within Enhanced Enforcement Zones, two tables are presented
for each time period. In the first of these tables speed data from the Test Year is
compared with the available historical speed data. Where possible speed data from the
three years prior to the MSMP are included in this table—however, in some cases data
are only available from one or two of the prior years. Also in some cases, speed data are
not available from the whole of the eight-week Enhanced Enforcement Period or the
four-week Regular Enhancement Period—in these cases the dates from which the data
are available are noted in the table. In the second of the two tables for each ATR the
focus is on drivers traveling at least 5 mph and at least 10 mph above the speed limit
adopted for the MSMP—i.e., on drivers traveling at 70 mph or more and at 75 mph or
more. In this second table, we present the number (and proportion) of vehicles traveling
above these speeds throughout the Third Enhanced Enforcement Period or the Third
Regular Enhancement Period. We also present the average number of vehicles traveling
above these speeds every day. Then, the table presents the decrease in the number of
vehicles relative to the number that were traveling at these speeds before the MSMP.
A4-55
ATR-172—Enhanced Enforcement Period #3
Table 4.1 (a): ATR-172—Comparison of Speed Data from Enhanced Enforcement
Period #3 with Speed Data from One Year Earlier
Measure
Test Period
(2/27/06 to 4/23/06)
Decrease/
Increase
Compared to
One Year Earlier
Mean (mph)
65.73255906
-0.27411**
Percent in 10 mph pace
71.7012274
+2.5362*
0.635011899
-0.023586*
0.166333185
-0.029793**
0.012341402
-0.004786*
0.002211098
-0.001087*
0.000624142
-0.000378*
770,658
762,541
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.1 (b): ATR-172—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
5.795787*
66.44034597
60.93639048
70.53032652
72.15378976
73.777253
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-56
Table 4.2 (a): ATR-172—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Enhanced Enforcement Period #3 and the Previous Year
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Test Period
(2/27/06 to
4/23/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
128,186
2,289
-410
9,511
170
-66
770,658
13,762
—
Table 4.2 (b): ATR-172—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Enhanced Enforcement Period #3 and the Previous Year
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(2/27/06 to
4/23/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.166333
0.166333
-0.029793
0.012341
0.012341
-0.004786
770,658
13,762
—
A4-57
ATR-172—Regular Enforcement Period #3
Table 4.3 (a): ATR-172—Comparison of Speed Data from Regular Enforcement
Period #3 with Speed Data from One Year Earlier
Measure
Test Period
(4/24/06 to 5/21/06)
Decrease/Increase
Compared to One
Year Earlier
Mean (mph)
66.04556
-0.48623**
Percent in 10 mph pace
72.9264
+1.8928*
0.651083
-0.041656*
0.164758
-0.039792*
0.012941
-0.006461*
0.002328
-0.001333*
0.000693
-0.000534*
435,986
440,270
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.3 (b): ATR-172—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
5.20629*
66.55331
61.2754
70.48603
72.13275
73.77948
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-58
Table 4.4 (a): ATR-172—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Regular Enforcement Period #3 and the Previous Year
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Test Period
(4/24/06 to
5/21/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
71,832
2,565
-620
5,642
202
-101
435,986
15,571
—
Table 4.4 (b): ATR-172—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Regular Enforcement Period #3 and the Previous Year
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(4/24/06 to
5/21/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.164758
0.164758
-0.039792
0.012941
0.012941
-0.006461
435,986
15,571
—
A4-59
ATR-187—Enhanced Enforcement Period #3
Table 4.5 (a): ATR-187—Comparison of Speed Data from Enhanced Enforcement
Period #3 with Speed Data from Two Previous Years
Measure
Test Period
(2/27/06 to
4/23/06)
Decrease/
Increase
Compared to
Two Years
Earlier
Decrease/
Increase Compared
to
Three Years
Earlier
(Four Weeks Only
1/30/03 to 2/26/03)
Mean (mph)
67.7337239
-1.85236**
-1.54354
Percent in 10 mph
pace
64.411299
-9.228**
-4.08437
0.74180931
-0.112066**
-0.085265**
0.34348076
-0.147374**
-0.088504**
0.06399494
-0.030404**
-0.052323**
0.01048778
-0.006245*
-0.016865**
0.00221293
-0.0000348*
-0.002128*
995,063
975,193
449,493
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.5 (b): ATR-187—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
6.58467*
68.0352998
62.3628974
73.4613699
74.3558697
76.3077635
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-60
Table 4.6 (a): ATR-187—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Enhanced Enforcement Period #3 and Speed Data from Two and Three
Years Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
341,785
6,103
-2,624
-1,573
63,679
1,137
-540
-930
995,063
17,769
—
—
Table 4.6 (b): ATR-187—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Enhanced Enforcement Period #3 and Speed Data from Two and Three Years
Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
0.343481
0.343481
-0.147374
-0.088504
0.063995
0.063995
-0.030404
-0.052323
995,063
17,769
—
—
A4-61
ATR-187—Regular Enforcement Period #3
Table 4.7 (a): ATR-187—Comparison of Speed Data from Regular Enforcement
Period #3 with Speed Data from Two Earlier Years
Measure
Test Period
(4/24/06 to
5/21/06)
Decrease/Increase
Compared to
Two Years Earlier
Decrease/Increase
Compared to
Three Years Earlier
(Four Weeks Only)
Mean (mph)
67.2731
-2.30396**
-2.04955**
Percent in 10
mph pace
62.6818
-10.8964**
-8.14288**
0.71029
-0.142086**
-0.124906**
0.325628
-0.161342**
-0.144879**
0.058837
-0.034667**
-0.034396**
0.009576
-0.007611*
-0.009594*
0.001939
-0.000597*
-0.001268*
570,387
570,497
577,401
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.7 (b): ATR-187—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
7.06030*
67.73344
61.848
73.29149
74.22856
75.89698
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-62
Table 4.8 (a): ATR-187—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Regular Enforcement Period #3 and Speed Data from Two and Three Years
Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
185,734
6,633
-3,287
-2,951
33,560
1,199
-706
-701
570,387
20,370
—
—
Table 4.8 (b): ATR-187—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Regular Enforcement Period #3 and Speed Data from Two and Three Years Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
0.325628
0.325628
-0.161342
-0.144879
0.058837
0.058837
-0.034667
-0.034396
570,387
20,370
—
—
A4-63
ATR-188—Enhanced Enforcement Period #3
Table 4.9 (a): ATR-188—Comparison of Speed Data from Enhanced Enforcement
Period #3 with Speed Data from One and Three Years Earlier
Decrease/Increase
Compared to
Three Years
Earlier
(Four Weeks Only
2/27/03 to 3/26/03)
Measure
Test Period
(2/27/06 to 4/23/06)
Decrease/
Increase
Compared to
One Year
Earlier
Mean (mph)
64.8689
-2.54135235**
-1.70709584**
Percent in 10 mph pace
54.2369
-3.7033675*
+4.43459*
0.520708
-0.190656**
-0.106283**
0.238763
-0.128764**
-0.101366**
0.055342
-0.041888**
-0.059604**
0.006029
-0.005795
-0.026912**
0.001504
-0.0007829*
-0.0092968**
1,581,209
1,554,599
778,838
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.9 (b): ATR-188—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
7.78738*
65.36723
57.79462
72.41965
73.78263
75.54163
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-64
Table 4.10 (a): ATR-188—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Enhanced Enforcement Period #3 and Speed Data from One and Three
Years Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
377,534
6,742
-3,636
-2,862
87,507
1,563
-1,183
-1,683
1,581,209
28,236
—
—
Table 4.10 (b): ATR-188—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Enhanced Enforcement Period #3 and Speed Data from One and Three Years
Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.238763
0.238763
-0.128764
-0.101366
0.055342
0.055342
-0.041888
-0.059604
1,581,209
28,236
—
—
A4-65
ATR-188—Regular Enforcement Period #3
Table 4.11 (a): ATR-188—Comparison of Speed Data from Regular Enforcement
Period #3 with Speed Data from One and Three Years Earlier
Measure
Test Period
(4/24/06 to 5/21/06)
Decrease/Increase
Compared to
One Year Earlier
Mean (mph)
60.93073
-6.37319**
-5.91166**
Percent in 10 mph pace
61.6701
+3.8461**
+10.8920**
0.228577
-0.454410**
-0.411706**
0.078027
-0.268985**
-0.269362**
0.015727
-0.073192**
-0.102416**
0.002909
-0.007179*
-0.031980**
0.001505
-0.000449*
-0.009790**
844,751
847,660
873,448
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Decrease/Increase
Compared to
Three Years Earlier
Table 4.11 (b): ATR-188—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
7.20781*
60.93898
55.40714
67.60966
69.27023
72.24932
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-66
Table 4.12 (a): ATR-188—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Regular Enforcement Period #3 and Speed Data from One and Three Years
Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
65,913
2,354
-8,115
-8,127
13,285
474
-2,208
-3,090
844,751
30,170
—
—
Table 4.12 (b): ATR-188—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Regular Enforcement Period #3 and Speed Data from One and Three Years Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.078027
0.078027
-0.268985
-0.269362
0.015727
0.015727
-0.073192
-0.102416
844,751
30,170
—
—
A4-67
ATR-197—Enhanced Enforcement Period #3
Table 4.13 (a): ATR-197—Comparison of Speed Data from Enhanced Enforcement
Period #3 with Speed Data from Two and Three Years Earlier
Measure
Test Period
(2/27/06 to
4/23/06)
Decrease/Increase
Compared to
Two Years Earlier
Decrease/Increase
Compared to
Three Years
Earlier
(Four Weeks Only
2/27/03 to 3/26/03)
Mean (mph)
65.3132
-0.5382**
-0.30081**
Percent in 10 mph
pace
73.397
+8.8962**
+2.6335*
0.601784
-0.016317*
+0.062144**
0.146793
-0.078318**
-0.038075**
0.015465
-0.013651**
-0.009033*
0.003743
-0.003291*
-0.002015*
0.001051
-0.001090*
ns
240,741
245,675
106,990
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.13 (b): ATR-197—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
6.33221*
66.11852
60.70331
69.96475
71.78152
73.68515
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-68
Table 4.14 (a): ATR-197—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Enhanced Enforcement Period #3 and Speed Data from Two and Three
Years Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
35,339
631
-337
-164
3,723
66
-59
-39
240,741
4,299
—
—
Table 4.14 (b): ATR-197—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Enhanced Enforcement Period #3 and Speed Data from Two and Three Years
Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.146793
0.146793
-0.078318
-0.038075
0.015465
0.015465
-0.013651
-0.009033
240,741
4,299
—
—
A4-69
ATR-197—Regular Enforcement Period #3
Table 4.15 (a): ATR-197—Comparison of Speed Data from Regular Enforcement
Period #3 with Speed Data from Two Prior Years
Measure
Test Period
(4/24/06 to
5/21/06)
Decrease/Increase
Compared to
Two Years Earlier
Decrease/Increase
Compared to
Three Years Earlier
Mean (mph)
65.74797
-0.32354**
-0.30216**
Percent in 10 mph
pace
0.698803
+6.16605**
+5.80551**
0.618687
-0.011208*
-0.006063*
0.177053
-0.058147**
-0.056950**
0.020199
-0.012260*
-0.012710*
0.004533
-0.003313*
-0.002826*
0.001206
-0.001239*
-0.000885*
130,153
131,271
130,998
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.15 (b): ATR-197—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
5.91837*
66.34373
60.79148
70.86237
72.45621
74.05005
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-70
Table 4.16 (a): ATR-197—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Regular Enforcement Period #3 and Speed Data from Two and Three Years
Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test
Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
23,044
823
-270
-265
2,629
94
-57
-59
130,153
4,648
—
—
Table 4.16 (b): ATR-197—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Regular Enforcement Period #3 and Speed Data from Two and Three Years Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
0.177053
0.177053
-0.058147
-0.056950
0.020199
0.020199
-0.012260
-0.012710
130,153
4,648
—
—
A4-71
4.2. Speed Data from One ATR located Outside Enhanced Enforcement Zones
There was one ATR located on a 4-Lane Divide Highway Outside the Enhanced
Enforcement Zones. It was ATR-353, on MNTH-169 near Jordan in Scott County.
There were no changes in enforcement at this location. For this ATR, the speed data
obtained during 2005, when the MSMP occurred, was compared with historical speed
data. Comparisons are presented for the eight-week time period between 2/27/06 and
4/23/06, when the Third Enhanced Enforcement Period occurred during the MSMP, and
then for the four-week time period between 4/24/06, when the Third Regular
Enhancement Period occurred.
Two tables are presented for each of these time periods. In the first table, speed data
from the Test Year is compared with historical speed data. Speed data was only available
for the two years prior to the MSMP for ATR-353. In the second table, the focus is on
drivers who were traveling at least 5 mph and at least 10 mph above the speed limit—i.e.,
drivers traveling at 70 mph or more and at 75 mph or more. In this second table, we
present the number (and proportion) of vehicles traveling above these speeds throughout
the six-week Enhanced Enforcement Period or the four-week Regular Enhancement
Period. We also present the average number of vehicles traveling above these speeds
every day. Then, the table presents the decrease in the number of vehicles relative to the
number that were traveling at these speeds in the two years prior to the implementation of
the MSMP.
A4-72
ATR-353—Enhanced Enforcement Period #3
Table 4.17 (a): ATR-353—Comparison of Speed Data from Enhanced Enforcement
Period #3 with Speed Data from the Two Prior Years
Decrease/Increase
Compared to
One Year Earlier
Decrease/Increase
Compared to
Two Years Earlier
Measure
Test Period
(Three Weeks Only
2/27/06 to 3/6/06
& 3/20/06 to3/26/06
&4/17/06 to 4/23/06)
(All Eight Weeks)
(All Eight Weeks)
Mean (mph)
67.60686515
-0.69892**
-0.70770**
Percent in 10 mph pace
67.4234849
-1.1444*
-1.4222*
0.753309238
-0.047159**
-0.048775**
0.327270777
-0.073747**
-0.071240**
0.031162925
-0.016710*
-0.017347*
0.003861045
-0.002085*
-0.002224*
0.000598462
-0.000281*
-0.000269*
466,195
1,180,206
1,161,608
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.17 (b): ATR-353—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Three Weeks Only
2/27/06 to 3/6/06
& 3/20/06 to3/26/06
&4/17/06 to 4/23/06)
5.715541*
67.97284472
62.53347396
72.99334814
73.8376351
74.68192207
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-73
Table 4.18 (a): ATR-353—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Enhanced Enforcement Period #3 and Speed Data from the Two Previous
Years
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Test Period
(Three Weeks Only
(2/27/06 to 3/6/06
& 3/20/06 to3/26/06
&4/17/06 to 4/23/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
152,572
7,265
-1,637
-1,582
14,528
692
-371
-385
466,195
22,200
—
—
Table 4.18 (b): ATR-353—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Enhanced Enforcement Period #3 and Speed Data from the Two Previous Years
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(Three Weeks
Only
(2/27/06 to 3/6/06
& 3/20/06
to3/26/06 &4/17/06
to 4/23/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
0.327271
0.327271
-0.073747
-0.071240
0.031163
0.031163
-0.016710
-0.017347
466,195
22,200
—
—
A4-74
ATR-353—Regular Enforcement Period #3
Table 4.19 (a): ATR-353—Comparison of Speed Data from Regular Enforcement
Period #3 with Speed Data from the Three Previous Years
Decrease/Increase
Compared to
Three Years
Earlier
Measure
Test Period
(4/24/06 to
5/21/06)
Decrease/Increase
Compared to
One Year Earlier
Decrease/Increase
Compared to
Two Years
Earlier
Mean (mph)
67.6135
-0.67775**
-0.62665**
-0.54776**
Percent in 10
mph pace
66.8946
-1.5626*
-1.19453*
-0.90690*
0.756731
-0.041384*
-0.039078*
-0.035679*
0.337889
-0.060842**
-0.058040**
-0.049271*
0.033125
-0.015327*
-0.015703*
-0.016954*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
100 mph or
more
0.00398
-0.0021603*
-0.002357*
-0.002835*
0.000034373
ns
ns
ns
Vehicle Total
640,029
636,670
627,432
608,392
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.19 (b): ATR-353—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
6.06037*
68.06478
62.54872
73.08254
73.90284
74.72315
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-75
Table 4.20 (a): ATR-353—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Regular Enforcement Period #3 and During the Previous Three Years
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
216,259
7,724
-1,391
-1,327
-1,126
21,201
757
-350
-359
-388
640,029
22,858
—
—
—
Table 4.20 (b): ATR-353—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Regular Enforcement Period #3 and During the Previous Three Years
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.337889
0.337889
-0.060842
-0.058040
-0.049271
0.033125
0.033125
-0.015327
-0.015703
-0.016954
640,029
22,858
—
—
—
4.3. Overall Effect of the MSMP on 4-Lane Divided Highways
In the MSMP, we obtained speed data from five ATRs located on 4-Lane Divided
Highways. Four of these ATRs were located Within Enhanced Enforcement Zones, while
the remaining ATR was located Outside the Enhanced Enforcement Zones. At the
locations of the four ATRs Within the Enhanced Enforcement Zones and the ATRs
Outside the Enhanced Enforcement Zones, the speed limit was unchanged—at 65 mph—
during the MSMP.
In order to provide a brief overall summary of the effect of the MSMP, speed data from
the four ATRs Within Enhanced Enforcement Zones were combined. For this summary,
A4-76
again we focused on drivers traveling at least 10 mph above the speed limit—i.e., on
drivers traveling at 75 mph or more. Then, we compared speed data from the Test Year
with data from previous years—in the case of ATR-172 and ATR-188 the data are from
one year earlier, while the data for ATR-187 and ATR-197 are from two years earlier.
Table 4.21 shows the results of this comparison for the Third Enhanced Enforcement
Period.
Table 4.21: Effect of the MSMP at Four ATRs Within Enhanced Enforcement
Zones on 4-Lane Divided Highways during the Third Enhanced Enforcement
Period
Sample Total
3,538,008*
Sample Total
3,587,671
One Year Before MSMP
# Over 75 mph
263,423*
Third Enhanced Enforcement Period
# Over 75 mph
164,420
% Over 75 mph
7.45*
% Over 75 mph
4.58
Result: 38.52% Reduction in Drivers Traveling Over 75 mph
*Data for ATR-172 and ATR-188 are from one year earlier; data for ATR-187 and 197are from two years
earlier.
Table 4.21 indicates that, for the four ATRs located Within Enhanced Enforcement Zones
on 4-Way Divided Highways, during the Third Enhanced Enforcement Period, there was
a 38.52% decrease in the number of drivers traveling over 75 mph—i.e., 10 mph over the
speed limit.
A similar comparison was conducted for the Third Regular Enforcement Period. Again,
the data for ATR-172 and ATR-188 are from one year earlier, the data for ATR-187 are
from two years earlier, and data for ATR-187 are from three years earlier. The results of
this comparison are shown in Table 4.22.
Table 4.22: Effect of the MSMP at Four ATRs Within Enhanced Enforcement
Zones on 4-Lane Divided Highways during Third Regular Enforcement Period
Sample Total
1,989,698*
Sample Total
1,981,277
One Year Before MSMP
# Over 75 mph
141,520*
Third Regular Enforcement Period
# Over 75 mph
55,116
% Over 75 mph
7.11*
% Over 75 mph
2.78
Result—60.90% Reduction in Drivers Traveling Over 75 mph
*Data for ATR-172 and ATR-188 are from one year earlier; data for ATR-187 and 197are from two years
earlier.
A4-77
Table 4.23 shows that, for the ATRs Within Enhanced Enforcement Zones on 4-Way
Divided Highways, during the Third Regular Enforcement Period there was a 60.90%
reduction in the number of drivers traveling over 75 mph—i.e., 10 mph or more above
the speed limit.
We also examined the difference between the speed data obtained during the Test Periods
from the single ATR Outside the Enhanced Enforcement Zones. For comparison
purposes, we again focused on drivers traveling at 75 mph or more—10 mph above the
speed limit. The results of this comparison for speed data obtained during the Third
Enhanced Enforcement Period are shown in Table 4.24.
Table 2.24: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on a 4-Way Divided Highway During the Third Enhanced Enforcement Period
Sample Total
1,180,206
Sample Total
466,195
One Year Before MSMP
# Over 75 mph
56,500
Third Enhanced Enforcement Period
# Over 75 mph
14,528
% Over 75 mph
4.78
% Over 75 mph
3.12
Result: 34.73% Reduction in Drivers Traveling Over 75 mph
Table 4.25 shows that, for the single ATR located Outside the Enhanced Enforcement
Zones on a 4-Way Divided Highway, during the Third Enhanced Enforcement Period,
there was a 34.73% decrease in the number of drivers traveling over 75 mph—i.e., 10
mph or more above the speed limit.
A similar comparison was conducted for the Third Regular Enforcement Period. The
results of this comparison are shown in Table 4.26.
Table 4.26: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on a 4-Way Divided Highway During the Third Regular Enforcement Period
Sample Total
636,670
Sample Total
640,029
One Year Before MSMP
# Over 75 mph
30,848
Third Regular Enforcement Period
# Over 75 mph
21,201
% Over 75 mph
4.85
% Over 75 mph
3.31
Result—31.75% Reduction in Drivers over 75 mph
Table 4.26 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
a 4-Way Divided Highway, during the Third Regular Enforcement Period there was a
A4-78
31.75% decrease in the number of drivers traveling over 75 mph—i.e., at 10 mph over
the speed limit.
Comparisons between speed data from the ATRs located Within Enhanced Enforcement
Zones and the ATR located Outside the Enhanced Enforcement Zones should be treated
with caution. The four ATRs located Within Enhanced Enforcement Zones are scattered
throughout Minnesota; in contrast, the single ATR Outside the Enhanced Enforcement
Zones is located a few miles to the South-West of the Twin Cities—and a great number
of the drivers traveling past this ATR may have traveled through Enhanced Enforcement
Zones in the Cities.
A4-79
Section 5. Speed Data Obtained on Rural Freeways
We obtained speed data from five ATRs located on Rural Freeways. Four of these ATRs
were located Within Enhanced Enforcement Zones, while the remaining ATR was located
Outside the Enhanced Enforcement Zones. At all five ATR locations, the speed limit was
unchanged—at 70 mph—during the MSMP.
In this section of the report, for the ATRs located Within Enhanced Enforcement Zones
and the single ATR located Outside the Enhanced Enforcement Zones, we present
comparisons of the speed data obtained during the Test Year with speed data obtained at
those same ATRs prior to the MSMP. Comparisons using the speed data from the ATRs
located Within Enhanced Enforcement Zones are presented first. Then, we present
comparisons using the speed data from the ATR located Outside the Enhanced
Enforcement Zones.
In making the comparisons between the speed data obtained during the Test Year and the
speed data obtained prior to the MSMP, we used two statistical tests. The first test was
used to examine differences in the mean speeds—for this we used the procedure for
comparing population means outlined by Kitchens (1987, p 369-373). The second test
was used to explore differences in the percentage of vehicles in the 10 mph pace and in
the differences in the proportions of vehicle traveling at various speeds. For this test, we
treated the distribution of speeds as a Bernoulli population—i.e., a population in which
each element is one of two possibilities, in this case, (1) in or out of the 10 mph pace, or
(2) above or below a selected speed (e.g., 75 mph). We then used the procedure for
comparing population proportions described by Kitchens (1987, pages 400-404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
ATR in the time periods under consideration. Second, the tests were conducted using an
extremely conservative correction, using n-values equal to the number of hours in each
test period—the rationale for this was that it is possible, when traffic is congested, that
individual vehicles may travel at speeds which are not independent of each other.
5.1. Speed Data from ATRs located Within Enhanced Enforcement Zones
The four ATRs located Within Enhanced Enforcement Zones on Rural Freeways were as
follows: (1) ATR-175, on I-94, near Saulk Centre in Stearns County, (2) ATR-191, on I35, near Wyoming, in Chisago County, (3) ATR-208, on I-35, near Owatanna in Steele
County, and (4) ATR-227, on I-90, near Alden in Freeborn County. During the MSMP,
there was no change in the speed limit—it remained at 70 mph—at the locations of these
four ATRs. The effect of the MSMP on the speed data at each of these four ATRs is
reported in this section. It is reported ATR by ATR—with the effect of the MSMP in the
Third Enhanced Enforcement Period followed by its effect in the Third Regular
Enhancement Period.
A4-80
For each of the four ATRs Within Enhanced Enforcement Zones, two tables are presented
for each time period. In the first of these tables, speed data from the Test Year are
compared with the available historical speed data. Where possible speed data from the
three years prior to the MSMP are included in this table—however, in some cases data
are only available from one or two of the prior years. Also in some cases, speed data are
not available from the whole of the Third Enhanced Enforcement Period or the Third
Regular Enhancement Period—in these cases the dates from which the data are available
are noted in the table. In the second of the two tables for each of the ATRs, the focus is
on drivers traveling at least 5 mph and at least 10 mph above the speed limit—i.e., on
drivers traveling at 75 mph or more and at 80 mph or more. In this second table, we
present the number (and proportion) of vehicles traveling above these speeds throughout
the six-week Enhanced Enforcement Period or the four-week Regular Enhancement
Period. We also present the average number of vehicles traveling above these speeds
every day. Then, the table presents the decrease in the number of vehicles relative to the
number that were traveling at these speeds before the MSMP.
A4-81
ATR-175—Enhanced Enforcement Period #3
Table 5.1 (a): ATR-175—Comparison of Speed Data from Enhanced Enforcement
Period #3 with Speed Data from the Three Previous Years
Measure
Test Period
(2/27/06 to
4/23/06)
Decrease/
Increase
Compared To
One Year
Earlier
(All Eight
Weeks)
Decrease/
Increase
Compared To
Two Years
Earlier
(All Eight
Weeks)
Decrease/
Increase
Compared To
Three Years
Earlier
(Four Weeks
Only)
Mean (mph)
71.73637
-1.43988**
-1.5702**
+0.860916**
Percent in 10
mph pace
67.2519
+3.6755**
+3.7134**
+16.5018**
0.903023
-0.019045*
-0.018066*
0.104393**
0.704877
-0.066457**
-0.069851**
0.133023**
0.231940
-0.151078**
-0.158991**
-0.054197**
0.029659
-0.050379**
-0.055793**
-0.058212**
0.003255
-0.007024**
-0.009201**
-0.021183**
1,065,061
1,077,686
1,093,228
495,780
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.1 (b): ATR-175—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
5.31025*
72.16601
66.33799
77.0254
78.26131
79.49722
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-82
Table 5.2 (a): ATR-175—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Enhanced Enforcement Period #3 and During the Previous Three Years
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
247,030
4,411
-2,873
-3,024
-1,030
31,589
564
-958
-1,061
-1,107
1,065,061
19,019
—
—
—
Table 5.2 (b): ATR-175—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Enhanced Enforcement Period #3 and During the Previous Three Years
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.231940
0.231940
-0.151078
-0.158991
-0.054197
0.029659
0.029659
-0.050379
-0.055793
-0.058212
1,065,061
19,019
—
—
—
A4-83
ATR-175—Regular Enforcement Period #3
Table 5.3 (a): ATR-175—Comparison of Speed Data from Regular Enforcement
Period #3 with Speed Data from the Three Previous Years
Decrease/Increase Decrease/Increase Decrease/Increase
Compared to
Compared to
Compared to
Three Years
Two Years
One Year
Earlier
Earlier
Earlier
Measure
Test Period
(4/24/06 to
5/21/06)
Mean (mph)
71.496298
-1.749641**
-1.867092**
+0.726762**
Percent in 10
mph pace
67.2293
+3.2741*
+3.5426*
+14.2278**
0.895765
-0.027454*
-0.026650*
+0.091376**
0.682347
-0.091563**
-0.094822**
+0.114315**
0.216062
-0.165979**
-0.177738**
-0.051943**
0.027405
-0.053794**
-0.060222**
-0.045628**
0.002988
-0.008208*
-0.009400**
-0.013291**
585,012
607,204
602,442
599,377
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.3 (b): ATR-175—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
5.31947*
71.95532
66.07218
76.75085
78.076
79.40115
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-84
Table 5.4 (a): ATR-175—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Regular Enforcement Period #3 and During the Previous Three Years
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
126,399
4,514
-3,468
-3,713
-1,085
16,032
573
-1,124
-1,258
-953
585,012
20,893
—
—
—
Table 5.4 (b): ATR-175—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Regular Enforcement Period #3 and During the Previous Three Years
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.216062
0.216062
-0.165979
-0.177738
-0.051943
0.027405
0.027405
-0.053794
-0.060222
-0.045628
585,012
20,893
—
—
—
ATR-191: Enhanced Enforcement Period #3
Throughout the Third Enhanced Enforcement Period, there were problems with the speed
data collected at ATR-191. However, these problems were with data collection in one of
the Southbound lanes—and, by using speed data only from the Northbound lanes, we
were able to make the comparisons with the historical speed data that appear in Table 5.5
and Table 5.6.
A4-85
Table 5.5 (a): ATR-191—Comparison of Speed Data from Enhanced Enforcement
Period #3 with Speed Data from the Three Previous Years
Increase
Compared to
One Year
Earlier
Decrease/
Increase
Compared to
Two Years
Earlier
Measure
(Northbound
Lanes Only)
(All Lanes)
(All Lanes)
Decrease/
Increase
Compared to
Three Years
Earlier
(All Lanes)
(Four Weeks
Only)
Mean (mph)
70.939912
-2.977900**
-1.405802
-0.99188**
Percent in 10
mph pace
59.93020
+0.16006*
+1.66004
+13.8902**
0.866866
-0.062042**
-0.030160**
0.055702**
0.586409
-0.174082**
-0.097931**
-0.033573*
0.253515
-0.198466**
-0.082066**
-0.103428**
0.047796
-0.081633**
-0.029790**
-0.101973**
0.008619
-0.012974**
-0.007562*
-0.021164**
1,098,874
2,324,100
2,279,562
1,067,581
Decrease/
Test Period
(2/27/06 to
4/23/06)
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.5 (b): ATR-191—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
(Northbound
Lanes Only)
7.03181*
71.297849
65.300696
77.515934
78.731185
79.946437
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-86
Table 5.6 (a): ATR-191—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Enhanced Enforcement Period #3 and During the Previous Three Years
Test Period
(2/27/06 to
4/23/06)
Measure
Number of vehicles
at 75 mph or more
Number of vehicles
at 80 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
(Northbound
Lanes Only)
Daily
Average
in Test
Period
278,581
4,975
-3,894
-1,610
-2,030
52,522
938
-1,602
-585
-2,001
1,098,874
19,623
—
—
—
Table 5.6 (b): ATR-191—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Enhanced Enforcement Period #3 and During the Previous Three Years
(Northbound
Lanes Only)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.253515
0.253515
-0.198466
-0.082066
-0.103428
0.047796
0.047796
-0.081633
-0.029790
-0.101973
1,098,874
19,623
—
—
—
Test Period
(2/27/06 to
4/23/06)
Measure
Proportion of
vehicles at 75 mph
or more
Proportion of
vehicles at 80 mph
or more
Vehicle Total
ATR-191—Regular Enforcement Period #3
There were also problems with the speed data collected at ATR-191 throughout the Third
Regular Enforcement Period. As in the Enhanced Enforcement Period, the data
collection problems were with one of the Southbound lanes. Again, by using speed data
the Northbound lanes, we were able to make the comparisons with the historical speed
data that appear in Table 5.7 and Table 5.8.
A4-87
Table 5.7 (a): ATR-191—Comparison of Speed Data from Regular Enforcement
Period #3 with Speed Data from the Two Prior Years
Decrease/Increase Decrease/Increase
Compared to
Compared to
Three Years
Two Years
Earlier
Earlier
(All Lanes)
(All Lanes)
Measure
Test Period
(4/24/06 to
5/21/06)
(Northbound
Lanes Only)
Mean (mph)
70.542455
-2.357357
-1.248332**
Percent in 10
mph pace
59.213801
-0.34899*
+13.9819**
0.842266
-0.071293**
+0.044467**
0.555099
-0.156799**
-0.054042**
0.240139
-0.119153**
-0.111143**
0.045036
-0.041277**
-0.101386**
0.008461
-0.015663**
-0.022811**
616,346
1,097,578
1,245,084
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.7 (b): ATR-191—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
(Northbound
Lanes Only)
7.18102*
70.874699
64.661081
77.310047
78.591421
79.872795
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-88
Table 5.8 (a): ATR-191—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Regular Enforcement Period #3 and Speed Data from Two and Three Years
Earlier
(Northbound
Lanes Only)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
148,009
5,286
-2,623
-2,447
27,758
991
-909
-2,232
616,346
22,012
—
—
Test Period
(4/24/06 to
5/21/06)
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Table 5.8 (b): ATR-191—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Regular Enforcement Period #3 and Speed Data from Two and Three Years Earlier
(Northbound
Lanes Only)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.240139
0.240139
-0.119153
-0.111143
0.045036
0.045036
-0.041277
-0.101386
616,346
22,012
—
—
Test Period
(4/24/06 to
5/21/06)
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
ATR-208: Enhanced Enforcement Period #3 and Regular Enforcement Period #3
There were also problems with the speed data collected at ATR-208, throughout the
Third Enhanced Enforcement Period and Third Regular Enforcement Period. Because
these data were unreliable, we were could not make reliable comparisons with the
historical speed data.
A4-89
ATR-227: Enhanced Enforcement Period #3
Table 5.9 (a): ATR-227—Comparison of Speed Data from Enhanced Enforcement
Period #3 with Speed Data from the Previous Two Years
Measure
Test Period
(2/27/06 to
4/23/06)
Decrease/Increase
Compared to
One Year Earlier
Decrease/Increase
Compared to
Two Years Earlier
Mean (mph)
70.428175
-0.87045**
-1.26803**
Percent in 10 mph
pace
65.61269
+2.9151*
+5.0063**
0.858067
-0.021784*
-0.018370*
0.629616
-0.037616**
-0.056952**
0.197491
-0.058674**
-0.094429**
0.020987
-0.009892*
-0.017549**
0.003282
-0.001788*
-0.003163*
402,534
475,798
499,040
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.9 (b): ATR-227—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
7.145877*
71.499756
65.176552
76.345332
77.761728
79.178124
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-90
Table 5.10 (a): ATR-227—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Enhanced Enforcement Period #3 and Speed Data from the Two Previous
Years
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
79,496
1,420
-422
-679
8,448
151
-71
-126
402,534
7,188
—
—
Table 5.10 (b): ATR-227—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Enhanced Enforcement Period #3 and Speed Data from the Two Previous Years
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
0.197491
0.197491
-0.058674
-0.094429
0.020987
0.020987
-0.009892
-0.017549
402,534
7,188
—
—
A4-91
ATR-227—Regular Enforcement Period #3
Table 5.11 (a): ATR-227—Comparison of Speed Data from Regular Enforcement
Period #3 with Speed Data from the Previous Two Years
Decrease/Increase Decrease/Increase
Compared to
Compared to
Three Years
Two Years
Earlier
Earlier
Measure
Test Period
(4/24/06 to
5/21/06)
Decrease/Increase
Compared to
One Year Earlier
Mean (mph)
70.980222
-0.206397**
-0.752534**
4.861502**
Percent in 10
mph pace
65.307968
+4.3615*
+6.11498**
+14.9849**
0.870018
+0.009468*
0.0027425*
+0.224921**
0.650458
+0.002696*
-0.028091*
+0.327491**
0.210542
-0.042457*
-0.088722**
+0.116119**
0.023609
-0.008539*
-0.017911*
+0.004116*
0.004141
-0.001207*
-0.003048*
ns
252,828
257,096
256,095
266,662
Proportion at
65 mph or
more
Proportion at
70 mph or
more
Proportion at
75 mph or
more
Proportion at
80 mph or
more
Proportion at
85 mph or
more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.11 (b): ATR-227—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
6.18182*
71.710078
65.455874
76.619356
77.956731
79.294105
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are
A4-92
Table 5.12 (a): ATR-227—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Regular Enforcement Period #3 and During the Previous Three Years
Measure
Number of vehicles
at 75 mph or more
Number of vehicles
at 80 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
53,231
1,901
-383
-801
+1,049
5,969
213
-77
-162
+37
252,828
9,030
—
—
—
Table 5.12 (b): ATR-227—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Regular Enforcement Period #3 and During the Previous Three Years
Measure
Proportion of
vehicles at 75 mph
or more
Proportion of
vehicles at 80 mph
or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.210542
0.210542
-0.042457
-0.088722
+0.116119
0.023609
0.023609
-0.008539
-0.017911
+0.004116
252,828
9,030
—
—
—
A4-93
5.2. Speed Data from One ATR located Outside Enhanced Enforcement Zones
There was one ATR located on a Rural Freeway Outside the Enhanced Enforcement
Zones. It was ATR-200, on I-94, near Hasty in Wright County. During the MSMP, at
this ATR location the speed limit remained unchanged at 70 mph and there was no
change in enforcement. No historical speed data were available for the Third Enhanced
Period for this ATR. However, we were able to use Pre-MSMP speed data that came
from a 4 week period from 4/24/05 to 5/21/05. These data were compared with speed
data from the Third Enhanced Enforcement Period—these speed data were also the
historical data for the Third Regular Enhancement Period.
Two tables are presented for each time period. In the first table, speed data from the Test
Year is compared with the historical speed data. In the second table, the focus is on
drivers who were traveling at least 5 mph and at least 10 mph above the speed limit—i.e.,
drivers traveling at 75 mph or more and at 80 mph or more. We also present the average
number of vehicles traveling above these speeds every day. Then, the table presents the
decrease in the number of vehicles relative to the number that were traveling at these
speeds before the MSMP was implemented.
A4-94
ATR-200—Enhanced Enforcement Period #3
Table 5.13 (a): ATR-200—Speed Data from Enhanced Enforcement Period #3
Compared with Pre-MSMP Speed Data
Measure
Test Period
(2/27/06 to 4/23/06)
Decrease/Increase
Compared to Pre-Test
Period
(4/24/05 to 5/21/05)
Mean (mph)
72.557163
-0.753242**
Percent in 10 mph
pace
63.32741
+10.6329**
0.917736
0.034374**
0.743747
0.038951*
0.357557
-0.051799**
0.040647
-0.110189**
0.004471
-0.046516**
2,107,104
1,206,904
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.13 (b): ATR-200—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
6.22763*
73.155790
66.946570
78.274695
79.063563
79.852431
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-95
Table 5.14 (a): ATR-200—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Enhanced Enforcement Period #3 and During the Pre-MSMP Period
(4/24/05 to 5/21/05)
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Test Period
(2/27/06 to
4/23/06)
Daily
Average in
Test Period
Decrease/
Increase
Compared to Pre-Test
Period
(4/24/05 to 5/21/05)
753,409
13,454
-1,949
85,647
1,529
-4,146
2,107,104
37,627
—
Table 5.14 (b): ATR-200—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Enhanced Enforcement Period #3 and During the Pre-MSMP Period (4/24/05 to
5/21/05)
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Test Period
(2/27/06 to
4/23/06)
Daily
Average in
Test Period
Decrease/
Increase
Compared to Pre-Test
Period
(4/24/05 to 5/21/05)
0.357557
0.357557
-0.051799
0.040647
0.040647
-0.110189
2,107,104
37,627
—
A4-96
ATR-200—Regular Enforcement Period #3
Table 5.15 (a): ATR-200—Speed Data from Regular Enforcement Period #3
Compared with Speed Data from One Year Earlier
Decrease/Increase
Compared to
One Year Earlier
Measure
Test Period
(Two Weeks Only
4/24/05 to 04/30/05
Plus
5/15/06 to 05/21/06)
Mean (mph)
71.7625631
-1.54784**
Percent in 10 mph
pace
62.034083
+9.33954**
0.898317
+0.014955*
0.685091
-0.019705*
0.294746
-0.114600**
0.033947
-0.116888**
0.003660
-0.047326**
573,744
1,206,904
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
(All Four Weeks)
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.15 (b): ATR-220—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Two Weeks Only
4/24/05 to 04/30/05
Plus
5/15/06 to 05/21/06)
6.54546*
72.3708686
66.1330015
77.7750548
78.7336465
79.6922383
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-97
Table 5.16 (a): ATR-200—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Regular Enforcement Period #3 and During the Previous Year
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Test Period
(Two Weeks Only
4/24/05 to 04/30/05
and
5/15/06 to 05/21/06)
Daily
Average in
Test Period
Decrease/
Increase
Compared to One
Year Earlier
169,109
12,079
-4,697
19,477
1,391
-4,790
573,744
40,982
—
Table 5.16 (b): ATR-200—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Regular Enforcement Period #3 and During the Previous Year
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Test Period
(Two Weeks Only
4/24/05 to 04/30/05
and
5/15/06 to 05/21/06)
Daily
Average in
Test Period
Decrease/
Increase
Compared to One
Year Earlier
0.294746
0.294746
-0.114600
0.033947
0.033947
-0.116888
5.3. Overall Effect of the MSMP on Rural Freeways
In the MSMP, we obtained speed data from five ATRs located on Rural Freeways—four
of these ATRs were located Within Enhanced Enforcement Zones, while the remaining
ATR was located Outside the Enhanced Enforcement Zones. At the locations of all five
ATRs the speed limit remained unchanged at 70 mph.
In order to provide a brief overall summary of the effect of the MSMP, we compared the
speed data obtained during the MSMP with speed data from the previous year, focusing
on drivers traveling at least 10 mph above the speed limit—i.e., those traveling at 80 mph
or more. The speed data from two of the ATRs Within Enhanced Enforcement Zones
(ATR-175 and ATR-227) were reliable. There were data collection problems for ATR191, but these problems were with one of the Southbound lanes—and we were able to use
the speed data collected in the Northbound lanes. The speed data from the ATR-208
were also problematic—and these data were omitted. The data from ATR-175, ATR-191
(Northbound lanes only), and ATR-227) were combined. Table 5.17 shows the results of
A4-98
comparing data for the Third Enhanced Enforcement Period with speed data obtained one
year earlier.
Table 5.17: Effect of MSMP on Rural Freeways during the Third Enhanced
Enforcement Period at Three ATRs (ATR-175, ATR-191, and ATR-227) Within
Enhanced Enforcement Zones
Sample Total
3,877,584
Sample Total
3,665,343*
One Year Before MSMP
# Over 80 mph
401,754
Third Enhanced Enforcement Period
# Over 80 mph
145,081*
% Over 80 mph
10.36
% Over 80 mph
3.96*
Result: 61.78% Reduction in Drivers over 80 mph
*Numbers adjusted to account for limited availability of data from ATR-191 (i.e., from the Northbound
lanes only) during the time period
Table 5.17 indicates that, for three of the four ATRs Within Enhanced Enforcement
Zones on Rural Freeways, during the Third Enhanced Enforcement Period, there was a
61.78% decrease in the number of drivers traveling at over 80 mph—i.e., 10 mph over
the speed limit—as compared to the month before the MSMP was implemented.
A similar comparison was conducted for the Third Regular Enforcement Period. The
speed data from two of the ATRs Within Enhanced Enforcement Zones (ATR-175 and
ATR-227) were reliable. Again, there were data collection problems for ATR-191, but
these problems were with one of the Southbound lanes—and we were able to use the
speed data collected in the Northbound lanes. And the speed data from the ATR-208
were again problematic—and these data were omitted. The data from ATR-175, ATR191 (Northbound lanes only), and ATR-227) were combined. For this comparison speed
data from ATR-175, ATR-191, and ATR-227 were combined—speed data were not
available from ATR-208 for this period. Table 5.18 shows the results of this comparison
for the Third Regular Enforcement Period.
A4-99
Table 5.18: Effect of MSMP on Rural Freeways During the Third Regular
Enforcement Period at Three ATRs (ATR-175, ATR-191, and ATR-227) Within
Enhanced Enforcement Zones
Sample Total
1,961,878
Sample Total
2,070,532*
One Year Before MSMP
# Over 80 mph
152,305
Third Regular Enforcement Period
# Over 80 mph
77,517*
% Over 80 mph
7.76
% Over 80 mph
3.74*
Result: 51.80% Reduction in Drivers over 80 mph
*Numbers adjusted to account for limited availability of data from ATR-191 (i.e., from the Northbound
lanes only) during the time period
Table 5.18 indicates that, for three of the four ATRs located Within Enhanced
Enforcement Zones on Rural Freeways, during the Third Regular Enforcement Period,
there was a 51.80% decrease in the number of drivers traveling over 80 mph—i.e., 10
mph over the speed limit.
We also examined the difference between the speed data obtained during the Test Periods
from the ATR that was located Outside the Enhanced Enforcement Zones. We focused
on drivers traveling at 80 mph or more—10 mph above the speed limit. The results of
this comparison for speed data obtained during the Third Enhanced Enforcement Period
are shown in Table 5.19.
Table 5.19: Effect of the MSMP on One ATR Outside the Enhanced Enforcement
Zones on a Rural Freeway During Third Enhanced Enforcement Period
Pre-MSMP Speed Data from 4/24/05 to 5/21/05
# Over 80 mph
% Over 80 mph
182,044
15.08
Third Enhanced Enforcement Period
Sample Total
# Over 80 mph
% Over 80 mph
2,107,104
85,647
4.06
Sample Total
1,206,904
Result: 73.08% Reduction in Drivers Traveling over 80 mph
Table 5.19 shows that, for the ATR located Outside Enhanced Enforcement Zones on a
Rural Freeway, during the Third Enhanced Enforcement Period, there was a 73.08%
decrease in the number of drivers traveling over 80 mph.
A similar comparison was conducted for the Third Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 5.20.
A4-100
Table 5.20: Effect of MSMP at one ATR Outside the Enhanced Enforcement Zones
on a Rural Freeway During Third Regular Enforcement Period
Sample Total
1,206,904
Sample Total
573,744
One Year Before MSMP
# Over 80 mph
182,044
Third Regular Enforcement Period
# Over 80 mph
19,477
% Over 80 mph
15.08
% Over 80 mph
3.39
Result: 77.52% Reduction in Drivers Traveling over 80 mph
Table 5.20 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
a Rural Freeway, during the Third Regular Enforcement Period there was a 77.52%
decrease in the number of drivers traveling over 80 mph.
For Rural Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
Zones should be treated with caution. It should be noted that the location of ATR that
was located Outside the Enhanced Enforcement Zones is between Enhanced Enforcement
Zones to both the North-West and the South-East. It is likely that most drivers passing
this ATR will have traveled through one or other of the Enhanced Enforcement Zones. [It
should also be noted that there are no other ATRs Outside the Enhanced Enforcement
Zones on Rural Freeways that could have been considered for comparison purposes for
this study.]
A4-101
Section 6. Speed Data Obtained on Urban Freeways
We obtained speed data from four ATRs located on Urban Freeways. Three of these
ATRs were located Within Enhanced Enforcement Zones, while the remaining ATR was
located Outside the Enhanced Enforcement Zones. During the MSMP, at the locations of
the three ATRs Within the Enhanced Enforcement Zones, the speed limit was increased
from 55 mph to 60 mph and there was Enhanced Enforcement at various times. In
contrast, at the location of the ATR Outside the Enhanced Enforcement, the speed limit
remained unchanged at 55 mph and there was no change in the level of enforcement
during the MSMP.
In this section of the report, for the ATRs located Within Enhanced Enforcement Zones
and the single ATR located Outside the Enhanced Enforcement Zones, we present
comparisons of the speed data obtained during the Test Year with speed data obtained at
those same ATRs before the MSMP was implemented.
It should be noted that, for the three ATRs Within Enhanced Enforcement Zones, there is
only very limited historical speed data. There is only speed data collected in the weeks
just before the MSMP began—specifically, the data is from September 2005 (with, in
two cases, data from the last two days in August, 2005). The available data is not the
same for all three ATRs—the actual time periods for which data were available are noted
in the comparison tables below. The result of comparing this August/September data with
the data collected at various times throughout the year should be considered with some
caution, as there may be seasonal effects that confound the effects of the MSMP.
There is historical speed data for the ATR located Outside the Enhanced Enforcement
Zones.
Comparisons using the speed data from the ATRs located Within Enhanced Enforcement
Zones are presented first. Then, we present comparisons using the speed data from the
ATR located Outside the Enhanced Enforcement Zones.
In making the comparisons between the speed data obtained during the Test Year and the
speed data obtained prior to the MSMP, we used two statistical tests. The first test was
used to examine differences in the mean speeds—for this we used the procedure for
comparing population means outlined by Kitchens (1987, p 369-373). The second test
was used to explore differences in the percentage of vehicles in the 10 mph pace and in
the differences in the proportions of vehicle traveling at various speeds. For this test, we
treated the distribution of speeds as a Bernoulli population—i.e., a population in which
each element is one of two possibilities, in this case, (1) in or out of the 10 mph pace, or
(2) above or below a selected speed (e.g., 75 mph). We then used the procedure for
comparing population proportions described by Kitchens (1987, pages 400-404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
A4-102
ATR in the time periods under consideration. Second, the tests were conducted using an
extremely conservative correction, with n-values equal to the number of hours in each
test period—the rationale for this was that it is possible, when traffic is congested, that
individual vehicles may travel at speeds which are not independent of each other.
6.1. Speed Data from ATRs located Within Enhanced Enforcement Zones
The three ATRs located Within Enhanced Enforcement Zones on Urban Freeways were
as follows: (1) ATR 100, on Highway 100 near Brooklyn Center in Hennepin County, (2)
ATR I94, on I-94 South of the 57th Street Bridge in Hennepin County, and (3) ATR35WCD, on I-35W, near Roseville in Ramsey County. At the locations of all three of
these ATRs, the speed limit was increased from 55 mph to 60 mph during the MSMP.
The effect of the MSMP on the speed data at each of these three ATRs is reported in this
section. It is reported ATR by ATR—with the effect of the MSMP in the Third
Enhanced Enforcement Period followed by its effect in the Third Regular Enhancement
Period.
For each of the three ATRs Within Enhanced Enforcement Zones, two tables are
presented for each time period. In the first of these tables speed data from the Test Year
is compared with pre-MSMP speed data, which for these ATRs is limited to speed data
from September 2005 (and, in two cases, from the last two days in August, 2005)—the
specific dates from which data are available are noted in the table. In the second of the
two tables for each ATR, the focus is on drivers traveling at least 5 mph and at least 10
mph above the new speed limit adopted for the MSMP—i.e., on drivers traveling at 65
mph or more and at 70 mph or more. In this second table, we present the number (and
proportion) of vehicles traveling above these speeds throughout the Third Enhanced
Enforcement Period or the Third Regular Enhancement Period. We also present the
average number of vehicles traveling above these speeds every day. Then, the table
presents the decrease in the number of vehicles relative to the number that were traveling
at these speeds before the MSMP. It should be noted that before the MSMP was adopted,
these speeds (of 65 mph or more and 70 mph or more) were 10 mph and 15 mph above
the pre-MSMP speed limit.
A4-103
ATR-100—Enhanced Enforcement Period #3
Table 6.1 (a): ATR-100—Comparison of Speed Data from Enhanced Enforcement
Period #3 with Speed Data from Two Weeks in September 2005
Measure
Test Period
(2/27/06 to 4/23/06)
Decrease/Increase
Compared to PreTest Period
(9/12/05 to 9/25/05)
Mean (mph)
58.922668
-1.647910**
Percent in 10 mph pace
57.13026
-0.39487*
0.215132
-0.068112**
0.061774
-0.030408**
0.011919
-0.013306*
0.003335
-0.003146*
0.001036
-0.000716*
4,380,799
1,089,474
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.1 (b): ATR-100—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
10.99248*
60.639129
54.380818
67.123519
68.753690
71.180805
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-104
Table 6.2 (a): ATR-100—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph)
During Enhanced Enforcement Period #3 with Speed Data from Two Weeks in
September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(2/27/06 to 4/23/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05
942,449
16,829
-5,328
270,618
4,832
-2,379
4,380,799
78,229
—
Table 6.2 (b): ATR-100—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Enhanced Enforcement Period #3 with Speed Data from Two Weeks in September
2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(2/27/06 to 4/23/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05
0.215132
0.215132
-0.068112
0.061774
0.061774
-0.030408
4,380,799
78,229
—
A4-105
ATR-100—Regular Enforcement Period #3
Table 6.3 (a): ATR-100—Comparison of Speed Data from Regular Enforcement
Period #3 with Speed Data from Two Weeks in September 2005
Measure
Test Period
(4/24/06 to 5/21/06)
Decrease/Increase
Compared to PreTest Period
(9/12/05 to 9/25/05)
Mean (mph)
56.57408
-3.996494**
Percent in 10 mph pace
43.2763
-14.2487**
0.190116
-0.093128**
0.064624
-0.027557*
0.013736
-0.011489*
0.005113
-0.001367*
0.002113
0.000362*
2,287,738
1,089,474
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.3 (b): ATR-100—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
6.54546*
72.3708686
66.1330015
77.7750548
78.7336465
79.6922383
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-106
Table 6.4 (a): ATR-100—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph)
During Regular Enforcement Period #3 with Speed Data from Two Weeks in
September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(4/24/06 to 5/21/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05
434,935
15,533
-7,516
147,843
5,280
-2,252
2,287,738
81,705
—
Table 6.4 (b): ATR-100—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Regular Enforcement Period #3 with Speed Data from Two Weeks in September
2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(4/24/06 to 5/21/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05
0.190116
0.190116
-0.093128
0.064624
0.064624
-0.027557
2,287,738
81,705
—
A4-107
ATR-I94—Enhanced Enforcement Period #3
Table 6.5 (a): ATR-I94—Comparison of Speed Data from Enhanced Enforcement
Period #3 with Speed Data from Four Weeks in August and September 2005
Measure
Test Period
(2/27/06 to 4/23/06)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
60.359423
-3.185425**
Percent in 10 mph pace
56.990303
+1.33227*
0.264361
-0.148436**
0.112252
-0.044670**
0.033597
-0.025380**
0.008430
-0.011812*
0.002756
-0.005812*
6,791,060
3,409,707
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.5 (b): ATR-I94—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
10.24793*
61.137578
54.614024
68.759177
70.778848
73.957302
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-108
Table 6.6 (a): ATR-I94—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph)
During Enhanced Enforcement Period #3 with Speed Data from Four Weeks in
August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(2/27/06 to 4/23/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
1,795,290
1,795,290
-18,001
762,310
13,613
-5,417
6,791,060
121,269
—
Table 6.6 (b): ATR-I94—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Enhanced Enforcement Period #3 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(2/27/06 to 4/23/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
0.264361
0.264361
-0.148436
0.112252
0.112252
-0.044670
6,791,060
121,269
—
A4-109
ATR-I94—Regular Enforcement Period #3
Table 6.7 (b): ATR-I94—Comparison of Speed Data from Regular Enforcement
Period #3 with Speed Data from Four Weeks in August and September 2005
Measure
Test Period
(4/24/06 to 5/21/06)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
60.699607
-2.845241**
Percent in 10 mph pace
53.78104
-1.87698*
0.290428
-0.122369**
0.129340
-0.027582*
0.040965
-0.018013*
0.011038
-0.009204*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Proportion at
100 mph or more
0.003671
-0.004897*
0.000324
-0.0005131*
Vehicle Total
3,531,442
3,409,707
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.7 (b): ATR-I94—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
10.40589*
61.334795
54.615033
69.358724
71.659945
74.488801
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-110
Table 6.8 (a): ATR-I94—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph)
During Regular Enforcement Period #3 with Speed Data from Four Weeks in
August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(4/24/06 to 5/21/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
1,025,631
36,630
-15,434
456,755
16,313
-3,479
3,531,442
126,123
—
Table 6.8 (b): ATR-I94—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Regular Enforcement Period #3 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(4/24/06 to 5/21/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
0.290428
0.290428
-0.122369
0.129340
0.129340
-0.027582
3,531,442
126,123
—
A4-111
ATR-35WCD—Enhanced Enforcement Period #3
Table 6.9 (a): ATR-35WCD—Comparison of Speed Data from Enhanced
Enforcement Period #3 with Speed Data from Four Weeks in August and
September 2005
Measure
Test Period
(2/27/06 to 4/23/06)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
60.741242
+0.733466**
Percent in 10 mph pace
42.675209
-5.6122*
0.408922
+0.057074*
0.142445
+0.024991**
0.035363
+0.009029*
0.009208
+0.004014*
0.002953
+0.001764*
5,850,412
3,030,663
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.9 (b): ATR-35WCD—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
12.41770*
63.175469
53.145940
69.858249
71.981905
74.316560
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-112
Table 6.10 (a): ATR-35WCD—Comparison of the Daily Average Number of
Vehicles Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of
60 mph) During Enhanced Enforcement Period #3 with Speed Data from Four
Weeks in August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(2/27/06 to 4/23/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
2,392,362
42,721
+5,963
833,364
14,882
+2,611
5,850,412
104,472
—
Table 6.10 (b): ATR-35WCD—Comparison of the Proportion of Vehicles Traveling
at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Enhanced Enforcement Period #3 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(2/27/06 to 4/23/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
0.408922
0.408922
+0.057074
0.142445
0.142445
+0.024991
5,850,412
104,472
—
A4-113
ATR-35WCD—Regular Enforcement Period #3
Table 6.11 (a): ATR-35WCD —Comparison of Speed Data from Regular
Enforcement Period #3 with Speed Data from Four Weeks in August and
September 2005
Measure
Test Period
(4/24/06 to 5/21/06)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
59.342541
-0.665236**
Percent in 10 mph pace
39.2355
-9.05188**
0.373088
+0.021240*
0.122472
+0.005017*
0.029673
+0.003340*
0.007660
+0.002467*
0.002295
+0.001107*
3,064,319
3,030,663
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.11 (b): ATR-35WCD—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
13.50790*
62.399608
51.305920
69.450786
71.210778
73.904799
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-114
Table 6.12 (a): ATR-35WCD—Comparison of the Daily Average Number of
Vehicles Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of
60 mph) During Regular Enforcement Period #3 with Speed Data from Four Weeks
in August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(4/24/06 to 5/21/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
1,143,261
40,831
+2,325
375,292
13,403
+549
3,064,319
109,440
—
Table 6.12 (b): ATR-35WCD—Comparison of the Proportion of Vehicles Traveling
at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Regular Enforcement Period #3 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(4/24/06 to 5/21/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
0.373088
0.373088
+0.021240
0.122472
0.122472
+0.005017
3,064,319
109,440
—
A4-115
6.2. Speed Data from One ATR located Outside Enhanced Enforcement Zones
There was one ATRs that was located on an Urban Freeway Outside the Enhanced
Enforcement Zones. It was ATR-335, on I-35W at County Road 53 in Anoka County.
During the MSMP, at this ATR location the speed limit remained unchanged at 55 mph
and there were no changes in enforcement. For ATR-335, the speed data obtained during
2005, when the MSMP occurred, was compared with historical speed data. Comparisons
are presented for the eight-week time period between 2/27 and 4/23, when the Third
Enhanced Enforcement Period occurred during the MSMP, and then for the four-week
time period between 4/24 and 5/21, when the Third Regular Enhancement Period
occurred.
Two tables are presented for each of these time periods. In the first table speed data from
the Test Year is compared with the historical speed data. We include speed data from the
three years prior to the MSMP in this table. In the second table, the focus is on drivers
who were traveling at least 5 mph and at least 10 mph above the new speed limit adopted
for the MSMP—i.e., drivers traveling at 65 mph or more and at 70 mph or more. It
should be noted that during the MSMP, as well as during the three years before it was
adopted, these speeds (65 mph or more and 70 mph or more) were 10 mph and 15 mph
above the actual speed limit at the location of ATR-335. In this second table, we present
the number (and proportion) of vehicles traveling above these speeds throughout the
Third Enhanced Enforcement Period or the Third Regular Enhancement Period. We also
present the average number of vehicles traveling above these speeds every day. Then, the
table presents the decrease in the number of vehicles relative to the number that were
traveling at these speeds before the MSMP was implemented.
A4-116
Table 6.13 (a): ATR-335—Speed Data from Enhanced Enforcement Period #3
Compared with Speed Data from Three Previous Years
Test Period
(2/27/06 to
4/23/06)
Decrease/
Increase as
Compared to One
Year Earlier
Decrease/
Increase as
Compared to Two
Years Earlier
Measure
(All Eight Weeks)
(All Eight Weeks)
(Two Weeks Only)
Decrease/
Increase as
Compared to
Three Years
Earlier
(All Eight Weeks)
Mean (mph)
69.779380
-1.584321**
+0.266452**
-4.422469**
Percent in 10
mph pace
62.968499
+6.2932**
+10.8271**
+2.15008*
0.824064
-0.025173*
+0.062522**
-0.112353**
0.551383
-0.062364**
+0.016619*
-0.230289**
0.183398
-0.084591**
-0.041432*
-0.274054**
0.041754
-0.043891**
-0.000474*
-0.107189**
0.009137
-0.009819**
-0.000212*
-0.021999**
2,287,995
2,384,645
553,568
2,135,087
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.13 (b): ATR-335—Additional Speed Data from Enhanced Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(2/27/06 to
4/23/06)
8.25676*
70.698164
63.911376
76.178942
77.943923
79.708905
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-117
Table 6.14 (a): ATR-335—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #3 and During the Previous Three
Years
Measure
Number of vehicles
at 65 mph or more
Number of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
1,885,454
33,669
-1,028
+2,554
-4590
1,261,561
22,528
-2,548
+679
-9,409
2,287,995
40,857
—
—
—
Table 6.14 (b): ATR-335—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #3 and During the Previous Three Years
Measure
Proportion of
vehicles at 65 mph
or more
Proportion of
vehicles at 70 mph
or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(2/27/06 to
4/23/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.824064
0.824064
-0.025173
+0.062522
-0.112353
0.551383
0.551383
-0.062364
+0.016619
-0.230289
2,287,995
40,857
—
—
—
A4-118
ATR-210—Regular Enforcement Period #3
Table 6.15 (a): ATR-335—Speed Data from Regular Enforcement Period #3
Compared with Speed Data from Two Prior Years
Measure
Test Period
(4/24/06 to
5/21/06)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
69.706517
-1.534413**
-4.778666**
Percent in 10
mph pace
62.68971
+6.03636**
+3.6052
0.819309
-0.025578*
-0.118641**
0.536285
-0.068564**
-0.237908**
0.179073
-0.084289**
-0.291128**
0.040263
-0.043463**
-0.128956**
0.008712
-0.009900*
-0.031352**
1,228,470
1,262,150
1,216,267
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.15 (b): ATR-335—Additional Speed Data from Regular Enforcement
Period #3
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(4/24/06 to
5/21/06)
8.20691*
70.507892
63.819192
76.047228
77.848250
79.649272
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A4-119
Table 6.16 (a): ATR-335—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph)
During Regular Enforcement Period #3 and Speed Data from One and Three Years
Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
1,006,497
35,946
-1,122
-5,205
658,810
23,529
-3,008
-10,438
1,228,470
43,874
—
—
Table 6.16 (b): ATR-335—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Regular Enforcement Period #3 and Speed Data from One and Three Years Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(4/24/06 to
5/21/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Tw One
Year
Earlier
0.819309
0.819309
-0.025578
-0.118641
0.536285
0.536285
-0.068564
-0.237908
1,228,470
43,874
—
—
6.3. Overall Effect of the MSMP on Urban Freeways
In the MSMP, we obtained speed data from four ATRs located on Urban Freeways—
three of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining ATR was located Outside the Enhanced Enforcement Zones. The speed limit
was increased from 55 mph to 60 mph at the locations of the three ATRs Within
Enhanced Enforcement Zones, while the speed limit remained unchanged at 55 mph at
location of the ATR Outside the Enhanced Enforcement Zones
In order to provide a brief overall summary of the effect of the MSMP, speed data from
the three ATRs Within Enhanced Enforcement Zones were combined. For this summary,
A4-120
we focused on drivers traveling at least 10 mph above the new speed limit. Then, we
compared speed data collected during the Third Enhanced Enforcement Period with preMSMP speed data that were collected just before the Enhanced Enforcement began—this
data was collected two weeks during September 2005 for ATR-100, and four weeks
during August and September 2005 for ATR-I94 and ATR-35WCD. When the preMSMP data were collected the speed limit at the locations of the three ATRs was still 55
mph. Table 6.17 shows the results of this comparison for the Third Enhanced
Enforcement Period.
Table 6.17: Effect of MSMP at Three ATRs Within Enhanced Enforcement Zones
on Urban Freeways During the Third Enhanced Enforcement Period
Sample Total
8,619,318*
Sample Total
17,022,271
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879*
Third Enhanced Enforcement Period
# Over 70 mph
1,866,292
% Over 70 mph
12.67*
% Over 70 mph
10.96
Result: 13.50% Reduction in Drivers over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-100 (for two weeks only—as
opposed to four weeks for both ATR-I94 and ATR-35WCD) during the pre-MSMP time period.
Table 6.17 indicates that, for the three ATRs Within Enhanced Enforcement Zones on
Urban Freeways, during the Third Enhanced Enforcement Period, there was a 13.50%
decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the new
speed limit—as compared to the month before the MSMP was implemented.
A similar comparison was conducted for the Third Regular Enforcement Period. The
results of this comparison using speed data from the three ATRs are shown in Table 6.18.
Table 6.18: Effect of MSMP at Three ATRs Within Enhanced Enforcement Zones
on Urban Freeways During the Third Regular Enforcement Period
Sample Total
8,619,318*
Sample Total
8,883,499
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879*
Third Regular Enforcement Period
# Over 70 mph
979,890
% Over 70 mph
12.67*
% Over 70 mph
11.03
Result: 12.94% Reduction in Drivers over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-100 (for two weeks only—as
opposed to four weeks for both ATR-I94 and ATR-35WCD) during the pre-MSMP time period.
A4-121
Table 6.18 indicates that, for the three ATRs located Within Enhanced Enforcement
Zones on Urban Freeways, during the Third Regular Enforcement Period, there was a
12.94% decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the
new speed limit—as compared to the month before the MSMP was implemented.
We also examined the difference between the speed data obtained during the Test Periods
from the ATR that was located Outside the Enhanced Enforcement Zones. For this ATR
location there was no change in the level of enforcement during the MSMP and no
change in the speed limit. For comparison purposes, we focused on drivers traveling at
70 mph or more—while this is 10 mph above the new speed limit Within Enhanced
Enforcement Zones, it is 15 mph above the actual speed limit at the location of the ATR
Outside Enhanced Enforcement Zones. The results of this comparison for speed data
obtained during the Third Enhanced Enforcement Period are shown in Table 6.19.
Table 6.19: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on an Urban Freeway During the Third Enhanced Enforcement Period
Sample Total
2,384,645
Sample Total
2,287,993
One Year Before MSMP
# Over 70 mph
1,463,568
Third Enhanced Enforcement Period
# Over70 mph
1,261,561
% Over 70 mph
61.37
% Over 70 mph
55.13
Result: 10.16% Reduction in Drivers Traveling over 70 mph
Table 6.19 shows that, for the ATR located Outside Enhanced Enforcement Zones on an
Urban freeway, during the Third Enhanced Enforcement Period, there was a 10.16%
decrease in the number of drivers traveling over 70 mph—i.e., 10 mph above the new
speed limit Within Enhanced Enforcement Zones (and 15 mph above the current speed
limit Outside the Enhanced Enforcement Zones).
A similar comparison was conducted for the Third Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 6.20.
A4-122
Table 6.20: Effect of MSMP at One ATR Outside the Enhanced Enforcement Zones
on an Urban Freeway During the Third Regular Enforcement Period
Sample Total
1,262,150
Sample Total
1,228,470
One Year Before MSMP
# Over 70 mph
763,410
Third Regular Enforcement Period
# Over 70 mph
658,810
% Over 70 mph
60.48
% Over 70 mph
53.63
Result: 11.33 % Reduction in Drivers Traveling over 70 mph
Table 6.20 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
an Urban Freeway, during the Third Regular Enforcement Period there was a 11.33%
decrease in the number of drivers traveling over 70 mph—i.e., at 10 mph or more above
the new speed limit Within Enhanced Enforcement Zones (and 15 mph or more above the
current speed limit Outside Enhanced Enforcement Zones).
For Urban Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
Zones should be treated with caution. It should be noted that the location of ATR that
was located Outside the Enhanced Enforcement Zones is only a few miles to the North of
an Enforced Enforcement Zone. And, most of the drivers traveling North past this ATR
will have traveled through that Enhanced Enforcement Zone. [It should also be noted
that, the locations of all the other ATRs Outside the Enhanced Enforcement Zones on
Urban Freeways that might have been considered for comparison purposes for this study
are also very close to Enhanced Enforcement Zones.]
A4-123
Section 7. Crash Data
During the MSMP, crash data were available for all Minnesota trunk highways. These
trunk highways included 2-Lane/2-Way Highways, 4-Lane Highways, Rural Freeways,
and Urban Highways. Some of these highways had changes in speed limits during the
MSMP, some had enhanced enforcement during the MSMP, and speed data were
available from some of them. In all, there were twelve combinations of Road Type,
Speed Limits, and Enforcement Status. Table 7.1 lists the twelve combinations—along
with the availability of speed data and the total length of roadway for each combination.
Table 7.1: Combinations of Trunk Highway Type, Speed Limits During the MSMP,
and Enforcement Status (with Availability of Speed Data and Length of Roadway)
Type of
Roadway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
Speed Limits
Increased—from 55
mph to 60 mph
Unchanged at 55
mph
Increased—from 55
mph to 60 mph
4-Lane Divided
Highway
4-Lane Divided
Highway
Unchanged at 65
mph
Unchanged at 65
mph
Rural Freeway
Unchanged at 70
mph
Unchanged at 70
mph
Rural Freeway
Urban Freeway
Urban Freeway
Urban Freeway
Urban Freeway
Urban Freeway
Increased—from 55
mph to 60 mph
Unchanged at 55
mph
Unchanged at 60
mph
Unchanged at 60
mph
Unchanged at 55
mph
Enforcement
Status
(Within/Outside
Enhanced
Enforcement
Zone)
Within
Outside
Outside
Within
Outside
Availability of
Speed Data
Available/
Unavailable
Available
(ATR & Tube)
Available
(ATR)
Available
(Tube)
Total Length of
Highways
Segments
(in Miles)
316.790
Available
(ATR & Tube)
Available
(ATR)
52.219
7,593.783
474.511
550.525
Available
(ATR & Tube)
Available
(ATR)
265.246
27.337
Within
Available
(ATR)
Available
(ATR)
Unavailable
Outside
Unavailable
73.377
Within
Unavailable
11.234
Within
Outside
Within
Outside
A4-124
459.835
89.397
4.052
Table 7.1 shows that crash data were available from all the combinations for which speed
data were available, as well as from three combinations for which we did not have speed
data. The table also shows that there were great differences in the length of roadway in
each combination—the range was from 7,593.783 miles of 2-Lane/2-Way Highway, with
unchanged speed limits, that were outside the enhanced enforcement zones to 4.052 miles
of Urban Freeway, with unchanged speed limits, that were within the enhanced
enforcement zones.
While an enormous amount of speed data was available for analysis purposes, in contrast
there were orders of magnitude less crash data. Crash data become more stable as the
sample size increases—because of that, instead of analyzing them over individual road
segments, we analyzed the crash data in terms of the twelve combinations listed in Table
7.1. Also, we combined the crash data from the First, Second, and Third Enhanced
Enforcement Periods with the crash data from the First, Second, and Third Regular
Enforcement Periods. In Tables 7.2 through 7.13, we present the crash data from the
First, Second, and Third MSMP Test Periods so that it can be compared with historical
crash data taken from the same time period (i.e., between 9/26 and 5/213) over the
previous five years. However, please note that the Average Daily Traffic (ADT) values
used for the MSMP Period in Tables 7.2 through 7.13 are ADT values calculated for
traffic levels on the various highways in 2005—this is because ADT values for 2006 will
not be available until 2007. Also please note that the number of days over which the data
were collected was 238 (34 weeks) for the MSMP period and 1,191 days for the same
period over the last five year—i.e., 238 multiplied by five (years) plus 1 day (because
2004 was a leap year).
Table 7.2: Crash Data for 2-Lane/2-Way Highways for which the Speed Limit Was
Increased, from 55 mph to 60 mph, and that Were Within the Enhanced
Enforcement Zones during the First Three MSMP Test Periods
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 5/21/06)
316.790
3959.0038
238
4
7
25
Historical Crash
Data
316.790
3,884.5795
1,191*
22
40
107
54
132
144
234
0.7839
1.2563
1.3401
699
1,000
0.6823
1.0603
1.5011
*238 days multiplied by 5 (years) plus one day (because 2004 was a leap year)
A4-125
7.3: Crash Data for 2-Lane/2-Way Highways for which the Speed Limit Was
Unchanged, at 55 mph, and that Were Outside the Enhanced Enforcement Zones
during the First Three MSMP Test Periods
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 5/21/06)
7,593.783
2,539.9186
238
55
84
379
Historical Crash
Data
7,593.783
2,477.6094
1,191*
354
541
2,597
760
3,586
2,585
3,863
0.8415
1.2750
1.1981
14,073
21,151
0.9439
1.4714
1.5798
*238 days multiplied by 5 (years) plus one day (because 2004 was a leap year)
Table 7.4: Crash Data for 2-Lane/2-Way Highways for which the Speed Limit Was
Increased, from 55 mph to 60 mph, and that Were Outside the Enhanced
Enforcement Zones during the First Three MSMP Test Periods
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 5/21/06)
474.511
2,745.0887
238
3
2
19
Historical Crash
Data
474.511
2,715.3717
1,191*
14
33
119
35
143
119
178
0.5742
0.8677
0.9677
529
838
0.5461
0.8954
0.9123
*238 days multiplied by 5 (years) plus one day (because 2004 was a leap year)
A4-126
Table 7.5: Crash Data for 4-Lane Divided Highways for which the Speed Limit Was
Unchanged, at 65 mph, and that Were Within the Enhanced Enforcement Zones
during the First Three MSMP Test Periods
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 5/21/06)
52.219
16,844.8455
238
1
3
10
Historical Crash
Data
52.219
16,041.5372
1,191*
12
14
78
24
170
91
129
0.6162
0.8885
0.4777
525
799
0.8009
1.2178
1.2028
*238 days multiplied by 5 (years) plus one day (because 2004 was a leap year)
Table 7.6: Crash Data for 4-Lane Divided Highways for which the Speed Limit Was
Unchanged, at 65 mph, and that Were Outside the Enhanced Enforcement Zones
during the First Three MSMP Test Periods
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 5/21/06)
550.525
12,279.2783
238
11
16
87
Historical Crash
Data
550.525
11,793.0384
1,191*
57
125
712
216
1,127
762
1,092
0.6787
0.9783
0.6837
4,210
6,231
0.8058
1.2137
0.7372
*238 days multiplied by 5 (years) plus one day (because 2004 was a leap year)
A4-127
Table 7.7: Crash Data for Rural Freeways for which the Speed Limit Was
Unchanged, at 70 mph, and that Were Within the Enhanced Enforcement Zones
during the First Three MSMP Test Periods
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 5/21/06)
265.246
21,345.3377
238
8
10
88
Historical Crash
Data
265.246
20,189.9008
1,191*
48
78
388
137
702
724
967
0.7176
0.9959
0.5937
3,354
4,570
0.7165
1.0150
0.7526
*238 days multiplied by 5 (years) plus one day (because 2004 was a leap year)
Table 7.8: Crash Data for Rural Freeways for which the Speed Limit Was
Unchanged, at 70 mph, and that Were Outside the Enhanced Enforcement Zones
during the First Three MSMP Test Periods
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 5/21/06)
459.835
22,663.6713
238
6
11
129
Historical Crash
Data
459.835
21,764.0687
1,191*
61
74
695
267
1,220
1,075
1,488
0.5999
0.8346
0.2419
5,509
7,559
0.6342
0.8922
0.5118
*238 days multiplied by 5 (years) plus one day (because 2004 was a leap year)
A4-128
Table 7.9: Crash Data for Urban Freeways for which the Speed Limit Was
Increased, from 55 mph to 60 mph, and that Were Within the Enhanced
Enforcement Zones during the First Three MSMP Test Periods
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 5/21/06)
27.337
102,733.2401
238
2
4
27
Historical Crash
Data
27.337
101,179.2412
1,191*
13
34
216
136
630
442
611
0.9141
1.2283
0.2992
2,658
3,551
1.0779
1.4471
0.3946
*238 days multiplied by 5 (years) plus one day (because 2004 was a leap year)
Table 7.10: Crash Data for Urban freeways for which the Speed Limit Was
Unchanged, at 55 mph, and that Were Outside the Enhanced Enforcement Zones
during the First Three MSMP Test Periods
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 5/21/06)
89.397
90,578.2219
238
8
4
86
Historical Crash
Data
89.397
89,875.6198
1,191*
28
73
710
536
2,672
2,098
2,732
1.4176
1.8078
0.4151
12,313
15,796
1.6507
2.1129
0.2926
*238 days multiplied by 5 (years) plus one day (because 2004 was a leap year)
A4-129
Table 7.11: Crash Data for Urban Freeways for which the Speed Limit Was
Unchanged, at 60 mph, and that Were Within the Enhanced Enforcement Zones
during the First Three MSMP Test Periods
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 5/21/06)
4.052
97,906.2409
238
0
1
6
Historical Crash
Data
4.052
96,518.8460
1,191*
4
3
26
9
71
60
76
0.8049
1.0591
0.0000
373
477
1.0241
1.3418
0.8587
*238 days multiplied by 5 (years) plus one day (because 2004 was a leap year)
Table 7.12: Crash Data for Urban Freeways for which the Speed Limit Was
Unchanged, at 60 mph, and that Were Outside the Enhanced Enforcement Zones
during the First Three MSMP Test Periods
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 5/21/06)
73.377
91,627.8252
238
1
8
58
Historical Crash
Data
73.377
93,282.7384
1,191*
18
36
439
292
1,416
1,095
1,454
0.9087
1.1811
0.0625
6,342
8,251
1.0121
1.3156
0.2208
*238 days multiplied by 5 (years) plus one day (because 2004 was a leap year)
A4-130
Table 7.13: Crash Data for Urban Freeways for which the Speed Limit Was
Unchanged, at 55 mph, and that Were Within the Enhanced Enforcement Zones
during the First Three MSMP Test Periods
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 5/21/06)
11.234
128,504.4084
238
1
0
12
Historical Crash
Data
11.234
126,260.6517
1,191*
7
6
125
112
586
348
473
1.3767
1.7841
0.2911
2,152
2,876
1.7025
2.2246
0.4144
*238 days multiplied by 5 (years) plus one day (because 2004 was a leap year)
The crash data presented in Tables 7.2 through 7.13 are summarized below in Table 7.14.
The table shows the Crash Rate, the Severity Rate, and the Fatal Crash Rate for each
combination of road type, speed limit condition both Within and Outside the Enforcement
Zones between 9/26/05 and 5/21/06 (the first 34 weeks of the MSMP).
A4-131
Table 7.14: Crash Rate, Severity Rate, and Fatal Crash Rate for Each Combination
of Trunk Highway Type, Speed Limits During the MSMP, and Enforcement Zone
During the First 34 Weeks of the MSMP
Within
Road Type/
Speed Limit
2 Lane/2-Way Highway
Increase—55 to 60 mph
2 Lane/2-Way Highway
No Change—55 mph
4 Lane/Divided Highway
No Change—65 mph
Rural Freeway
Unchanged—70 mph
Urban Freeway
Increase—55 to 60 mph
Urban Freeway
No Change—55 mph
Urban Freeway
No Change—60 mph
Outside
Crash
Rate
Severity
Rate
Fatal
Crash
Rate
0.7839
1.2563
1.3401
0.5742
0.8677
0.9677
—
—
—
0.8415
1.2750
1.1981
0.6162
0.8885
0.4777
0.6787
0.9783
0.6837
0.7176
0.9959
0.5937
0.5999
0.8346
0.2419
0.9141
1.2283
0.2992
—
—
—
1.3767
1.7841
0.2911
1.4176
1.8078
0.4151
0.8049
1.0591
0.0000
0.9087
1.1811
0.0625
A4-132
Crash
Rate
Severity
Rate
Fatal
Crash
Rate
Section 8. Citation Data
During the Third MSMP Enhanced Enforcement Period citation data were collected for
the highways on which there was Enhanced Enforcement. In all, citation data were
collected for 32 regions—14 regions have ATRs in them, seven regions will have Tubes
in the Fourth Enhanced Enforcement Period, and the remaining eleven regions are next to
regions where there are ATRs or Tubes. The citation data for the 14 regions in which
there are ATRs are reported in the tables below; there is one table for each road type
included in the MSMP—i.e., 2-Lane/2-Way Highways, 4-Lane Highways, Rural
Freeways, and Urban Highways. The tables list the ATRs that were on the various road
types and their locations. The Tables also present the Number of Speed Citations and the
Number of Speed Warnings given during the Third Enhanced Enforcement Period, the
Number of Vehicles that were Stopped and the Number of Hours of Enforcement.
Table 8.1: Citation Data for 2-Lane/2-Way Highways on Which ATRs Were
Located
ATR
210
219
220
Location
US-71, 1 m. North of
Blackduck, Beltrami
US-2, South East of
Warba, Itasca
US-71, South of CR 89,
Hubbard
Total
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
112
682
868
456
189
443
706
432
76
363
479
240
377
1,488
2,053
1,128
Table 8.2: Citation Data for 4-Lane Divided Highways on Which ATRs Were
Located
ATR
172
187
188
197
Total
Location
US-10, West of
Dilworth, Clay
US-10, 0.8 miles West
of Rice, Benton
US-52, North of
Rochester, Olmstead
SR-60, 0.7 miles West
of junction with SR-4,
(St. James) Watonwan
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
92
251
347
176
205
272
564
294
204
304
576
294
97
257
389
196
598
1,084
1,876
960
A4-133
Table 8.3: Citation Data for Rural Freeways on Which ATRs Were Located
ATR
175
191
208
227
Location
I-94, 0.5 miles South
East of Saulk Centre,
Stearns
I-35, North of
Wyoming, Chisago
I-35, North of
Owatanna, Steele
I-90, East of Alden,
Freeborn
Total
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
332
251
647
294
237
266
559
304
303
715
1,124
288
85
93
202
90
957
1,325
2,532
976
Table 8.4: Citation Data for Urban Freeways on Which ATRs Were Located
ATR
100
I94
35WCD
Total
Location
Highway 100, near
Brooklyn Center,
Hennepin
I-94, South of 57th
Street Bridge,
Hennepin
I-35W, near Roseville,
Ramsey
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
625
442
1,257
469
516
363
990
409
1,535
817
2,528
869
2,676
1,622
4,775
1,747
The citation data for the individual highways that are presented in Tables 8.1 through 8.4
are summarized in Table 8.5. This table presents, for each of the four highway types, the
Number of Speed Citations and the Number of Speed Warnings that were given during
the Third Enhanced Enforcement Period, as well as the Number of Vehicles that were
Stopped and the Number of Hours of Enforcement.
A4-134
Table 8.5: Citation Data for the Four Types of Highways on Which ATRs Were
Located
Type of
Highway
2-Lane/2-Way
Highway
4-Lane Divided
Highway
Rural Freeway
Urban Freeway
Number of
Speed Citations
Number of
Speed Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
377
1,488
2,053
1,128
598
957
2,676
1,084
1,325
1,622
1,876
2,532
4,775
960
976
1,747
Total
4,608
5,519
11,236
4,811
A4-135
Appendix 5
Minnesota Speed Management Project: Deliverable #6—
Data Analysis for the Fourth Test Period
Kathleen A. Harder, Ph.D. and John R. Bloomfield, Ph.D.
Center for Human Factors Systems Research and Design
University of Minnesota, Suite 225
1425 University Ave. S.E.
Minneapolis, MN 55414
Contents
Page
Section 1. Introduction …………………………………………………………………..3
1.1 Background ……………………………………………………………….3
1.2 Organization of this Report ……………………………………………..6
Section 2. Summary of Findings during the Fourth MSMP Test Period ………..…….8
2.1 Overall Effect of the MSMP during the Fourth Enhanced
Enforcement and Fourth Regular Enforcement Period …………………..8
2.2 Effect of the MSMP on 2-Lane/2-Way Highways …………………………9
2.3 Effect of the MSMP on 4-Lane Divided Highways ………………………13
2.4 Effect of the MSMP on Rural Freeways …………………………………16
2.5 Effect of the MSMP on Urban Freeways ………………………………...19
2.6 Crash Rates During the Fourth MSMP Period ……………………….22
2.7 Citation Data During the Fourth MSMP Period ………………………..23
Section 3. Speed Data Obtained on 2-Lane/2-Way Highways …..……………………24
3.1 Speed Data Within the Enhanced Enforcement Zones …….……………25
3.2 Speed Data from One Tube Located Outside Enhanced
Enforcement Zones but in a Zone with a Speed Limit Change …………..44
3.3 Speed Data from ATRs Located Outside Enhanced
Enforcement Zones and in Zones with No Change
in Speed Limit ……………………………………………………………47
3.4 Overall Effect of the MSMP on 2-Lane/2-Way Highways ………………63
Section 4. Speed Data Obtained on 4-Lane Divided Highways ….…………………..68
4.1 Speed Data Within Enhanced Enforcement Zones
…………………68
4.2 Speed Data from One ATR Located Outside Enhanced
Enforcement Zones ………………………………………………………85
4.3 Overall Effect of the MSMP on 4-Lane Divided Highways ……………..89
Section 5. Speed Data Obtained on Rural Freeways ………………………………….93
5.1 Speed Data Within Enhanced Enforcement Zones ………..….…………93
5.2 Speed Data from One ATR Located Outside Enhanced
Enforcement Zones ……………………………………………..………109
5.3 Overall Effect of the MSMP on Rural Freeways ……………………….113
Section 6. Speed Data Obtained on Urban Freeways ………………………………..117
6.1 Speed Data from ATRs Located Within Enhanced
Enforcement Zones …………………………………………………..…118
6.2 Speed Data from One ATR Located Outside Enhanced
Enforcement Zones …………………………………………………..…131
6.3 Overall Effect of the MSMP on Urban Freeways ………………………135
Section 7. Crash Data ………………………………………………………………...139
Section 8. Citation Data ………………………………………………………………147
A5-2
Section 1. Introduction
1.1 Background
This report contains the results of the analysis of data obtained during the fourth testing
period of the Minnesota Speed Management Program (MSMP). The Minnesota Speed
Management Program (MSMP) is a cooperative project between the Minnesota
Department of Transportation (Mn/DOT) and the Minnesota Department of Safety
(DPS). The program, which ran from 9/26/05 to 8/13/06, involved:
• Raising the speed limit on select roadways in Minnesota from 55 mph to 60 mph
in order to align the speed limit more closely with the design speed of the
roadways.
• Increasing the presence of enforcement officers along selected areas of these
roadways and other high-design roadways for selected periods of time.
The MSMP involved the following four types of roadway—(1) 2-Lane/2-Way Highways,
(2) 4-Lane Divided Highways, (3) Rural Freeways, and (4) Urban Freeways.
This report presents the University of Minnesota’s assessment of effectiveness of the
MSMP during its fourth test period, between 5/22/06 and 8/13/06. The test period had
two phases—the Fourth Enhanced Enforcement Period, lasting eight weeks between
5/22/06 and 7/16/06; and the Fourth Regular Enforcement Period, lasting four weeks
between 7/17/06 and 8/13/06.
For the Fourth Enhanced Enforcement Period and the Fourth Regular Enforcement
Period, we analyzed speed data collected by Mn/DOT in order to determine whether there
were changes in speeds as a result of the MSMP. In addition, we analyzed crash data to
determine whether there were changes in crash rates. Some historical speed data and
crash data were available for comparison purposes—where possible, we compared the
data obtained in these two phases with historical data. Also, we analyzed citation data—
in this case however, there no historical citation data were available.
The speed data that were provided by Mn/DOT were collected from a number of
Automated Traffic Recorders (ATRs) and eight Data-Recording Tubes. The ATRs are
listed in Table 1.1. The ATRs are organized in the table in terms of the type of roadway
at which they are located—i.e., whether they are on 2-Lane/2-Way Highways, 4-Lane
Divided Highways, Rural Freeways, or Urban Freeways. The table lists their locations,
the speed limit (and whether or not it was changed for the MSMP), and whether they
were located Within or Outside an Enhanced Enforcement Zone.
A5-3
Table 1.1: ATRs Organized by Road Type
Type of
roadway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
ATR
210
219
220
179
198
199
222
4-Lane Divided
Highway
197
4-Lane Divided
Highway
4-Lane Divided
Highway
4-Lane Divided
Highway
4-Lane Divided
Highway
172
Rural Freeway
175
Rural Freeway
191
Rural Freeway
208
Rural Freeway
227
Rural Freeway
200
Urban Freeway
100
Urban Freeway
I94
Urban Freeway
35WC
D
335
Urban Freeway
187
188
353
Location
US-71, 1 m. North of
Blackduck, Beltrami
US-2, South East of Warba,
Itasca
US-71, South of CR 89,
Hubbard
USTH 59, South of Garvin,
Lyon
USTH 212, East of TH 23,
Chippewa
USTH 75, 0.55 m. N of Co
Rd. 69, Pipestone
MNTH 65, near Pliny,
Aitkin
Speed limit
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Unchanged at 55 mph
Within/
Outside
Enforcement
Zone
Within
Within
Within
Outside
Unchanged at 55 mph
Outside
Unchanged at 55 mph
Outside
Unchanged at 55 mph
Outside
SR-60, 0.7 miles West of
junction with SR-4, (St.
James) Watonwan
US-10, West of Dilworth,
Clay
US-10, 0.8 miles West of
Rice, Benton
US-52, North of Rochester,
Olmstead
TH 169, South of CR 59,
North of Jordan, Scott
Unchanged at 65 mph
Within
Unchanged at 65 mph
Within
Unchanged at 65 mph
Within
Unchanged at 65 mph
Within
Unchanged at 65 mph
Outside
I-94, 0.5 miles South East
of Saulk Centre, Stearns
I-35, North of Wyoming,
Chisago
I-35, North of Owatanna,
Steele
I-90, East of Alden,
Freeborn
I-94, Hasty, Wright
Unchanged at 70 mph
Within
Unchanged at 70 mph
Within
Unchanged at 70 mph
Within
Unchanged at 70 mph
Within
Unchanged at 70 mph
Outside
Highway 100, near
Brooklyn Center, Hennepin
I-94, South of 57th Street
Bridge, Hennepin
I-35W, near Roseville,
Ramsey
I-35W at County Road 53,
Anoka
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Increased—from 55
mph to 60 mph
Unchanged at 55 mph
Within
A5-4
Within
Within
Outside
The eight Data-Recording Tubes are listed in Table 1.2. In the table, the Tubes are
organized in terms of the type of roadway on which they were located. The table lists the
locations of the Tubes; whether during the MSMP the speed data were collected from all
lanes, or from a subset of the lanes; the speed limit at the location—and whether or not
the speed limit was changed for the MSMP; and whether the Tubes were located Within
or Outside the Enhanced Enforcement Zones.
Table 1.2: Tubes Organized by Road Type
Within/
Outside
Enforcement
Zone
Tube
Number
Lanes
Covered
Pre
MSMP
Lanes
Covered
in the
MSMP
Location
T01
(All
Lanes)
(All
Lanes)
MN-23,
Hanley Falls,
Lyon
T02
(All
Lanes)
(All
Lanes)
MN-7,
Montevideo,
Chippewa
2-Lane/2Way
Highway
T03
(All
Lanes)
(Southbound)
US-71,
Willmar,
Kandiyohi
2-Lane/
2-Way
Highway
T04
(Westbound)
(All
Lanes)
MN-7, Silver
Lake, McLeod
T08
(All
Lanes)
(All
Lanes)
US-53,
Ash Lake,
St Louis
Speed
limit
Increased
—from
55 mph
to 60 mph
Increased
—from
55 mph
to 60 mph
Increased
—from
55 mph
to 60 mph
Increased
—from
55 mph
to 60 mph
Increased
—from
55 mph
to 60 mph
T05
(Eastbound)
(Westbound)
MN-60,
Lake Crystal,
Blue Earth
Unchanged
at 65 mph
Within
(Eastbound)
(Eastbound)
(Passing
Lanes
Only)
I-94,
Fergus Falls,
Otter Tail
I-35,
Cloquet,
Carlton
Unchanged
at 70 mph
Within
Unchanged
at 70 mph
Within
Type of
roadway
2-Lane/
2-Way
Highway
2-Lane/
2-Way
Highway
2-Lane/
2-Way
Highway
4-Lane
Divided
Highway
Rural
Freeway
Rural
Freeway
T06
T07
(All
Lanes)
A5-5
Within
Within
Within
Within
Outside
From the speed data obtained with the ATRs and the Tubes, we derived several speed
measures for the Fourth Enhanced Enforcement Period and Fourth Regular Enforcement
Period. For the ATRs, the same measures were also derived from historical speed data
that were obtained during the same calendar time periods and, where possible, we used
historical speed data from the three years prior to the MSMP. For the Tubes the preMSMP speed data were collected in August of 2005.
In order to compare the MSMP speed data with the historical data, we conducted a series
of statistical tests in which the following measures were compared—(1) the mean speed,
(2) the percentage of vehicles in the 10 mph pace, (3) the proportion of vehicles traveling
at 65 mph or more, (4) the proportion of vehicles traveling at 70 mph or more, (5) the
proportion of vehicles traveling at 75 mph or more, (6) the proportion of vehicles
traveling at 80 mph or more, and (7) the proportion of vehicles traveling at 85 mph or
more. [Please note that in addition, we derived the following measures—(8) median
speed, (9) 15th percentile, (10) 85th percentile, (11) 90th percentile (12) 95th percentile, and
(13) the total number of vehicles—though we did not conduct statistical comparisons for
the median speed or the percentile measures. We did not conduct statistical analyses for
these measures because the comparisons are not valid. The speed data from which they
are derived are collected in one 40-mph bin (from 0.01 mph to 40.00 mph), nine 5-mph
bins (40.01 mph to 45.00 mph, 45.01 mph to 50.00 mph; 50.01 mph to 55.00 mph; 55.01
mph to 60.00 mph; 60.01 mph to 65.00 mph; 65.01 mph to 70.00 mph; 70.01 mph to
75.00 mph; 75.01 mph to 80.00 mph; and 80.01 mph to 85.00 mph), and one 15-mph bin
(from 85.01 mph to 100.00 mph) and no differentiation within the bins is possible, which
makes a statistical analysis invalid.]
To test for differences in the mean speeds we used the procedure for comparing
population means outlined by Kitchens (1987, p 369-373). For the comparisons
involving the percentage of vehicles in the 10 mph pace and proportions of vehicle
traveling at various speeds, we treated each distribution of speeds as a Bernoulli
population—i.e., a population in which each element is one of two possibilities, in this
case, (1) in or out of the 10 mph pace, or (2) above or below a selected speed (e.g., 75
mph). We then used the procedure for comparing population proportions described by
Kitchens (1987, pages 400-404). The statistical tests were conducted in two ways. First,
we conducted the tests in the traditional way, using n-values that were equal to the
number of vehicles that traveled by each ATRs or Tube in the test periods under
consideration. In the second, we used an extremely conservative correction, with nvalues that were equal to the number of hours in each test period—because it is likely
that, when traffic is congested, individual vehicles may travel at speeds which are not
independent of each other.
1.2 Organization of this Report
The next section of this report, Section 2, presents summary data. Then, detailed
analyses are presented in subsequent sections of the report. There is a section for each of
the four road types, with analyses of the speed data obtained at each of the ATRs (listed
A5-6
in Table 1.1) and Tubes (listed in Table 1.2). The final two sections of this report deal
with crash data and citation data.
A5-7
Section 2: Summary of Findings during the Fourth MSMP Test Period
In the MSMP, we obtained speed data from 21 ATRs and eight Tubes located throughout
Minnesota. Fourteen of the ATRs and seven of the Tubes were located Within Enhanced
Enforcement Zones, while the remaining ATRs and the remaining Tube were located
Outside Enhanced Enforcement Zones. Seven ATRs and five Tubes were located on 2Lane 2-Way Highways, five ATRs and one Tube were located on 4-Lane Divided
Highways, five ATRs and two Tubes were located on Rural Freeways, and four ATRs
were located on Urban Freeways. The effect of the MSMP on the speed data obtained at
these ATRs and Tubes is summarized in this section of the report.
2.1. Overall Effect of the MSMP during the Fourth Enhanced and Regular Enforcement
Periods
To provide a brief overall summary of the effect of the MSMP during the Fourth Test
Period on driving speeds, we focused on vehicles traveling at least 10 mph above the
speed limit at the locations of the ATRs and Tubes Within the Enhanced Enforcement
Zones during the MSMP. [It should be noted that, on the 2-Lane/2-Way Highways and
on the Urban Freeways, at the locations Within the Enhanced Enforcement Zones the
speed limits were increased from 55 mph to 60 mph, while at the locations Outside the
Enhanced Enforcement Zones the speed limits were unchanged at 55mph. Also, the
speed limits remained unchanged at 65 mph on 4-Lane Divided Highways and at 70 mph
on Rural Freeways.]
Table 2.1 shows the decrease or increase in the percentage of the vehicles traveling at
least 10 mph above the speed limit during the Fourth Enhanced Enforcement Period and
the Fourth Regular Enforcement Periods as compared to the percentages traveling at
those speeds before the MSMP was implemented. This means that, for the ATRs located
on the 2-Lane 2-Way Highways and the Urban Freeways, the percentages shown are for
vehicles traveling at 70 mph or more (10 mph above the new speed limit and 15 mph
above the pre-MSMP speed limit); while for the ATRs located on the 4-Lane Divided
Highways, the percentages shown are for vehicles traveling at 75 mph or more; and for
the ATRs located on the Rural Freeways, the percentages shown are for vehicles
traveling at 80 mph or more.
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Table 2.1: Summary of the Effect of the MSMP on the Percentage of Vehicles
Traveling at Least 10 mph Above the Speed Limits during the Fourth MSMP Period
Road type
2-Lane 2-Way
Highways
4-Lane Divided
Highways
Rural
Freeways
Urban
Freeways
Within the Enhanced Enforcement
Zones
Increase/
Increase/
Decrease during Decrease during
Fourth
Fourth
Regular
Enhanced
Enforcement
Enforcement
Period
Period
Outside the Enhanced Enforcement
Zones
Increase/
Increase/
Decrease during Decrease during
Fourth
Fourth
Regular
Enhanced
Enforcement
Enforcement
Period
Period
-20.96%
-15.90%
+113.18%
+89.03%
-46.27%
-28.53%
-35.29%*
-41.42%*
-37.69%
-38.74%
-73.98%*
-59.65%*
-11.92%**
-8.45%**
-3.36%*
*Speed data from one ATR located close to Enhanced Enforcement Zones.
-9.84%*
**Historical speed data used in comparisons obtained just before the start of the MSMP.
Table 2.1 shows that, for the all four highway types with ATRs located Within the
Enhanced Enforcement Zones, there were decreases in the percentages of vehicles
traveling at least 10 mph above the speed limits. The table also shows that, with one
exception, for the highways with ATRs located Outside the Enhanced Enforcement
Zones, there were also decreases in the percentage of vehicles traveling at least 10 mph
above the speed limits Within the Enhanced Enforcement Zones. The exception was for
the 2-Lane 2-Way Highways (for which there were four ATRs Outside the Enhanced
Enforcement Zones). It should be noted that for the other three road types, there was a
single ATR Outside the Enhanced Enforcement Zones—and that, in each case, the ATR
was located relatively close to one, or two, Enhanced Enforcement Zones.
The data from which Table 2.1 was derived for each of the four road types are presented
in more detail in the remainder of the section of the report.
2.2. Effect of the MSMP on 2-Lane 2-Way Highways
In the MSMP, we obtained speed data from seven ATRs and five Tubes located on 2Lane 2-Way Highways—although the Tube data were collected only in the Fourth
Regular Enforcement Period. Three of the ATRs and four of the Tubes were located
Within Enhanced Enforcement Zones: The speed limit was increased from 55 mph to 60
mph at the locations of these three ATRs and four Tubes. The fifth Tube was located
Outside the Enhanced Enforcement Zones but it was on a road where the speed limit was
increased from 55 mph to 60 mph. In contrast, the four remaining ATRs were located
Outside Enhanced Enforcement Zones and on roads where the speed limit remained
unchanged at 55 mph.
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In order to provide a brief overall summary of the effect of the MSMP during the Fourth
Enhanced Enforcement Period, we focused on drivers traveling at least 10 mph above the
new speed limit. Speed data from the three ATRs Within Enhanced Enforcement Zones
were combined. Then, we compared speed data from the Test Year with data from the
previous year, when the speed limit at the locations of the ATRs was still 55 mph. Table
2.2 shows the results of this comparison for the Fourth Enhanced Enforcement Period.
Table 2.2: Effect of the MSMP on 2-Lane 2-Way Highways during the Fourth
Enhanced Enforcement Period at Three ATRs Within Enhanced Enforcement Zones
Sample Total
468,353
Sample Total
446,518*
One Year Before MSMP
# Over 70 mph
20,538
Fourth Enhanced Enforcement Period
# Over 70 mph
15,484*
% Over 70 mph
4.39
% Over 70 mph
3.47*
Result: 20.96% Reduction in Drivers Traveling Over 70 mph
*Numbers adjusted to account for limited availability of speed data from ATR-210 (three weeks—as
opposed to eight weeks for ATR-219 and ATR-220) during the time period.
Table 2.2 indicates that, at the locations of the three ATRs Within Enhanced Enforcement
Zones on 2-Lane 2-Way Highways, during the Fourth Enhanced Enforcement Period,
there was a 20.96% decrease in the number of drivers traveling over 70 mph—i.e., 10
mph over the new speed limit.
A similar comparison was conducted for the Fourth Regular Enforcement Period. In this
case, however, no speed data were available from ATR-210, although speed data were
available from the four Tubes. The speed data from the Tubes and from the two ATRs
were combined. Then, we compared speed data from the Test Year with Pre-MSMP
speed data, when the speed limit at the locations of the ATRs and Tubes was still 55 mph.
It should be noted that the speed data that were used for comparison purposes for the two
ATRs were obtained in the same calendar time period one year earlier, while the
comparison data for the Tubes were obtained in August 2005, just before the beginning
of the MSMP. The results of this comparison are shown in Table 2.3.
A5-10
Table 2.3: Effect of the MSMP on 2-Lane 2-Way Highways during Fourth Regular
Enforcement Period at Two ATRs and Four Tubes Within Enhanced Enforcement
Zones
Sample Total
782,923*
Sample Total
780,955**
Pre-MSMP
# Over 70 mph
15,291*
Fourth Regular Enforcement Period
# Over 70 mph
12,812**
% Over 70 mph
1.95*
% Over 70 mph
1.64**
Result: 15.90% Reduction in Drivers Traveling Over 70 mph
*Numbers adjusted to account for limited availability of speed data from Tube 01, Tube 02 and Tube 03
(all one week) and Tube 04 (one week and Westbound lane only)—as compared to ATR-219 and ATR-220
(both four weeks)
**Numbers adjusted to account for limited availability of speed data from Tube 01, Tube 02 and Tube 04
(all one week) and Tube 03 (one week and Southbound lane only)—as compared to ATR-219 and ATR220 (both four weeks)
Table 2.3 shows that, during the Fourth Regular Enforcement Period, at the locations of
two of the ATRs and the four Tubes Within Enhanced Enforcement Zones on 2-Lane 2Way Highways, there was a 15.90% reduction in the number of drivers traveling over 70
mph—i.e., 10 mph over the speed limit.
For the Fourth Regular Enforcement Period, a similar comparison was conducted for the
speed data obtained at the location of the single Tube (Tube 05) that was on a 2-Lane/2Way Highway where the speed limit was changed from 55mph to 60 mph, but was
Outside the Enhanced Enforcement Zones. We compared speed data from the Test Year
with data obtained in August 2005, just before the beginning of the MSMP, when the
speed limit at the location of the Tube was still 55 mph. Table 2.4 shows the results of
this comparison for the Fourth Regular Enforcement Period.
Table 2.4: Effect of the MSMP on 2-Lane 2-Way Highways during Fourth Regular
Enforcement Period at One Tube that Was Outside Enhanced Enforcement Zones
but Where There Was a Change in the Speed Limit
Sample Total
28,824
Sample Total
27,006
Pre-MSMP
# Over 70 mph
1,227
Fourth Regular Enforcement Period
# Over 70 mph
1,133
% Over 70 mph
4.26
% Over 70 mph
4.20
Result: 1.41% Reduction in Drivers Traveling Over 70 mph
Table 2.4 shows that, during the Fourth Regular Enforcement Period, for the Tube
located Outside Enhanced Enforcement Zones on a 2-Lane 2-Way Highway, but where
A5-11
there was a change in speed limit, there was a 1.41% decrease in the number of drivers
traveling over 70 mph—i.e., 10 mph above the new speed limit and 15 mph above the
previous speed limit at this location.
We also examined the speed data obtained, during the Test Periods, from the four ATRs
Outside Enhanced Enforcement Zones, where there was no change in the level of
enforcement during the MSMP and no change in the speed limit. We compared this data
with speed data from the previous year, focusing on drivers traveling at 70 mph or
more—while this is 10 mph above the new speed limit Within Enhanced Enforcement
Zones, it is 15 mph above the actual speed limit at the locations of the four ATRs Outside
Enhanced Enforcement Zones. The results of this comparison for speed data obtained
during the Fourth Enhanced Enforcement Period are shown in Table 2.5.
Table 2.5: Effect of the MSMP on 2-Lane 2-Way Highways during the Fourth
Enhanced Enforcement Period at Four ATRs Outside Enhanced Enforcement Zones
Sample Total
512,597*
Sample Total
503,661**
Pre-MSMP
# Over 70 mph
13,195*
Fourth Enhanced Enforcement Period
# Over 70 mph
27,723**
% Over 70 mph
2.58*
% Over 70 mph
5.50**
Result: 113.18 Increase in Drivers Traveling Over 70 mph
*Numbers adjusted to account for limited availability of speed data from ATR-199 (4 weeks—as opposed
to 8 weeks for ATR-179, ATR-199, and ATR-222) during the time period; also, speed data from ATR-179,
ATR-198, and ATR-222 are from one year earlier, while data from ATR-199 are from two years earlier
**Numbers adjusted to account for limited availability of speed data from ATR-179 & ATR-198 (both 5
weeks—as opposed to 8 weeks for ATR-199 and ATR-222) during the time period.
Table 2.5 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on 2-Lane 2-Way Highways, during the Fourth Enhanced Enforcement Period, there was
a 113.18% increase in the number of drivers traveling over 70 mph—i.e., 10 mph above
the new speed limit Within Enhanced Enforcement Zones (and 15 mph above the current
speed limit Outside the Enhanced Enforcement Zones). It should be noted that the large
increase seen in the numbers of vehicles traveling over 70 mph indicated in Table 2.5 is
entirely due to the data from two of the ATRs (ATR-198 and ATR-222).
A similar comparison was conducted for the Fourth Regular Enforcement Period. The
results of this comparison using speed data from the four ATRs located Outside
Enhanced Enforcement Zones are shown in Table 2.6.
A5-12
Table 2.6: Effect of the MSMP on 2-Lane 2-Way Highways during the Fourth
Regular Enforcement Period at Four ATRs Outside Enhanced Enforcement Zones
Sample Total
255,326*
Sample Total
245,528**
Pre-MSMP
# Over 70 mph
7,098*
Fourth Regular Enforcement Period
# Over 70 mph
12,954**
% Over 70 mph
2.78*
% Over 70 mph
5.28**
Result: 89.93 Increase in Drivers Traveling over 70 mph
*Speed data from ATR-179 and ATR-198 are from one year earlier, while data from ATR-199 and ATR222 are from two years earlier
** Numbers adjusted to account for limited availability of speed data from ATR-222 (two weeks—as
opposed to four weeks for ATR-179, ATR-198, and ATR-199) during the time period.
Table 2.6 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on the 2-Lane 2-Way Highways, during the Fourth Regular Enforcement Period there
was a 89.93% increase in the number of drivers traveling over 70 mph—i.e., at 10 mph
over the new speed limit Within Enhanced Enforcement Zones (and 15 mph above the
current speed limit Outside Enhanced Enforcement Zones). Again, it should be noted
that the large increase seen in the numbers of vehicles traveling over 70 mph indicated in
Table 2.5 is entirely due to the data from two of the ATRs (ATR-198 and ATR-222).
Comparisons between speed data from the ATRs located Within Enhanced Enforcement
Zones and the ATRs located Outside Enhanced Enforcement Zones should be treated
with caution.
2.3. Effect of the MSMP on 4-Lane Divided Highways
In the MSMP, we obtained speed data from five ATRs and one Tube located on 4-Lane
Divided Highways. Unfortunately, the comparisons for the Tube are questionable and,
because of that, are not included in the summary tables that follow. With regard to the
ATRs, four were located Within Enhanced Enforcement Zones, while the remaining ATR
was located Outside the Enhanced Enforcement Zones. At the locations of the four
ATRs Within the Enhanced Enforcement Zones and the ATR Outside the Enhanced
Enforcement Zones, the speed limit was unchanged—at 65mph—during the MSMP.
In order to provide a brief overall summary of the effect of the MSMP, speed data from
the four ATRs Within Enhanced Enforcement Zones were combined. For summary
purposes, we focused on drivers traveling at least 10 mph above the speed limit—i.e., on
drivers traveling at 75 mph or more. Then, we compared speed data from the Test Year
with data from previous years—in the case of ATR-172 and ATR-188 the data are from
one year earlier, while for ATR-187 and ATR-197 the data are from two years earlier.
Table 2.7 shows the results of this comparison for the Fourth Enhanced Enforcement
Period.
A5-13
Table 2.7: Effect of the MSMP at Four ATRs Within Enhanced Enforcement Zones
on 4-Lane Divided Highways during the Fourth Enhanced Enforcement Period
Sample Total
4,317,053*
Sample Total
4,403,811**
Pre-MSMP
# Over 75 mph
271,441*
Fourth Enhanced Enforcement Period
# Over 75 mph
148,932**
% Over 75 mph
6.29*
% Over 75 mph
3.38**
Result: 46.27% Reduction in Drivers Traveling Over 75 mph
*Numbers adjusted to account for limited availability of data from ATR-187 (4 weeks—as opposed to eight
weeks for ATR-172, ATR-188, and ATR-197). Also, data for ATR-172 and ATR-188 are from one year
earlier, while data for ATR-187 and ATR-197 are from two years earlier.
**Numbers adjusted to account for limited availability of data from ATR-187 (32.125 days) and ATR-188
(21 days), as opposed to 56 days (all eight weeks) for ATR-172 and ATR-197.
Table 2.7 indicates that, for four ATRs located Within Enhanced Enforcement Zones on
4-Way Divided Highways, during the Fourth Enhanced Enforcement Period, there was a
46.27% decrease in the number of drivers traveling over 75 mph—i.e., 10 mph over the
speed limit. It should also be noted that speed data from ATR-188 heavily influenced the
resultant reduction. This is because ATR-188 was located on a section of US-52 that has
been under construction since April 2006. For several months prior to April 2006, there
were occasional lane closures and some utility, surveying, and building removal work
being conducted along TH 52—all these activities may have affected traffic speed. Also,
this area was targeted very heavily by enforcement. [If the data from ATR-188 are
removed from the comparison, the resultant reduction is 0.12% for the remaining ATRs.]
A similar comparison was conducted for the Fourth Regular Enforcement Period. For
this time period, the speed data were available for ATR-187 and ATR-197 (in both case
the comparison data were from two years earlier) and Tube 05 (for which the comparison
data were from August 2005). The results of this comparison are shown in Table 2.8.
Table 2.8: Effect of the MSMP at Two ATRs (ATR-187 and ATR-197) and one
Tube Within Enhanced Enforcement Zones on 4-Lane Divided Highways during the
Fourth Regular Enforcement Period
Sample Total
706,618*
Sample Total
833,036**
Pre-MSMP
# Over 75 mph
65,625*
Fourth Regular Enforcement Period
# Over 75 mph
55,351**
% Over 75 mph
9.29*
% Over 75 mph
6.64**
Result: 28.53 % Reduction in Drivers Traveling Over 75 mph
*Numbers adjusted to account for limited availability of data from ATR-187 (25.5 days—as opposed to 28
days for ATR-197. Also, the data for ATR-187 and ATR-197 are from two years earlier.
**Numbers adjusted to account for limited availability of data from ATR-187 (10.7 days—as opposed to
28 days from ATR-197.
A5-14
Table 2.8 shows that, for two ATRs Within Enhanced Enforcement Zones on 4-Way
Divided Highways, during the Fourth Regular Enforcement Period there was a 28.53%
reduction in the number of drivers traveling over 75 mph—i.e., 10 mph or more above
the speed limit.
We also examined the difference between the speed data obtained, during the Test
Periods and before the MSMP began, from the single ATR Outside the Enhanced
Enforcement Zones. For comparison purposes, we again focused on drivers traveling at
75 mph or more—10 mph above the speed limit. The results of this comparison for
speed data obtained during the Fourth Enhanced Enforcement Period are shown in Table
2.9.
Table 2.9: Effect of the MSMP at One ATR Outside the Enhanced Enforcement
Zones on a 4-Way Divided Highway During the Fourth Enhanced Enforcement
Period
Sample Total
1,293,813
Sample Total
1,293,359
One Year Before MSMP
# Over 75 mph
59,387
Fourth Enhanced Enforcement Period
# Over 75 mph
38,406
% Over 75 mph
4.59
% Over 75 mph
2.97
Result: 35.29% Reduction in Drivers Traveling Over 75 mph
Table 2.9 shows that, for the single ATR located Outside the Enhanced Enforcement
Zones on a 4-Way Divided Highway, during the Fourth Enhanced Enforcement Period,
there was a 35.29% decrease in the number of drivers traveling over 75 mph—i.e., 10
mph or more above the speed limit.
A similar comparison was conducted for the Fourth Regular Enforcement Period. The
results of this comparison are shown in Table 2.10.
Table 2.10: Effect of the MSMP at One ATR Outside the Enhanced Enforcement
Zones on a 4-Way Divided Highway During the Fourth Regular Enforcement Period
Sample Total
682,852
Sample Total
655,603
One Year Before MSMP
# Over 75 mph
34,606
Fourth Regular Enforcement Period
# Over 75 mph
19,477
% Over 75 mph
5.07
% Over 75 mph
2.97
Result: 41.42% Reduction in Drivers Traveling over 75 mph
A5-15
Table 2.10 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
a 4-Way Divided Highway, during the Fourth Regular Enforcement Period there was a
41.42% decrease in the number of drivers traveling over 75 mph—i.e., at 10 mph over
the speed limit.
Comparisons between speed data from the ATRs located Within Enhanced Enforcement
Zones and the ATR located Outside the Enhanced Enforcement Zones should be treated
with caution. The four ATRs located Within Enhanced Enforcement Zones are scattered
throughout Minnesota; while the single ATR Outside the Enhanced Enforcement Zones
is located a few miles to the South-West of the Twin Cities—and many of the drivers
traveling past this ATR may have traveled through Enhanced Enforcement Zones in the
Cities.
2.4. Effect of the MSMP on Rural Freeways
In the Fourth MSMP Period, we obtained speed data from five ATRs and one Tube that
were located on Rural Freeways. [Unfortunately, the speed data for a second Tube were
collected from different lanes in the MSMP than in the Pre-MSMP period, as a result, the
comparison between the two time periods was compromised.] Four of the ATRs and the
Tube for which we had comparable data were located Within Enhanced Enforcement
Zones, while the fifth ATR was located Outside the Enhanced Enforcement Zones. At all
the ATR and Tube locations, the speed limit was unchanged—at 70 mph—during the
MSMP.
In order to provide a brief overall summary of the effect of the MSMP, we compared the
speed data obtained during the MSMP with speed data from previous years, focusing on
drivers traveling at least 10 mph above the speed limit—i.e., those traveling at 80 mph or
more. The speed data from two of the ATRs Within Enhanced Enforcement Zones
(ATR-175 and ATR-227) from the Northbound lanes of ATR-191 were reliable and were
combined. [The speed data from the ATR-208 were problematic—and these data were
omitted.] Table 2.11 shows the results of comparing data for the Fourth Enhanced
Enforcement Period with speed data obtained one year earlier for ATR-175 and ATR227, and two years earlier for ATR-227.
A5-16
Table 2.11: Effect of the MSMP at Three ATRs (ATR-175, ATR-191, and ATR227) Within Enhanced Enforcement Zones on Rural Freeways during the Fourth
Enhanced Enforcement Period
Sample Total
4,830,882*
Sample Total
2,465,892**
Pre-MSMP Data
# Over 80 mph
388,557*
Fourth Enhanced Enforcement Period
# Over 80 mph
123,430**
% Over 80 mph
8.04*
% Over 80 mph
5.01**
Result: 37.69% Reduction in Drivers Traveling over 80 mph
*Numbers adjusted to account for limited availability of data from ATR-227 (for four weeks only—as
opposed to eight weeks for both ATR-175 and ATR-191) during the pre-MSMP time period: Also, data for
ATR-175 and ATR-227 are from one year earlier; while data for ATR-191 are from two years earlier.
**Numbers are based on four weeks of speed data from all lanes for ATR-175 and ATR-227 and eight
weeks of data from the Northbound lanes for ATR-191
Table 2.11 indicates that, for three of the four ATRs Within Enhanced Enforcement
Zones on Rural Freeways, during the Fourth Enhanced Enforcement Period, there was a
37.69% decrease in the number of drivers traveling at over 80 mph—i.e., 10 mph over
the speed limit—as compared to the same calendar time period one (or two) years before
the MSMP was implemented.
A similar comparison was conducted for the Fourth Regular Enforcement Period—this
time, with the addition of the speed data from Tube 06. Within the Enhanced
Enforcement Zones, the speed data from all lanes of ATR-175 and ATR-227, from the
Northbound lanes of ATR-191, and from Tube 06 were reliable—and these data were
combined. [Again, the speed data from ATR-208 were problematic—and, as a result,
were omitted. Table 2.12 shows the results of comparing the speed data from the Fourth
Regular Enforcement Period with speed data obtained one year earlier for ATR-175 and
ATR-227, two years earlier for ATR-227, and from one week during the month before
the MSMP was implemented for Tube 06.
A5-17
Table 2.12: Effect of the MSMP at Three ATRs (ATR-175, ATR-191, and ATR227) and One Tube Within Enhanced Enforcement Zones on Rural Freeways
During the Fourth Regular Enforcement Period
Sample Total
2,951,239*
Sample Total
3,010,699**
Pre-MSMP
# Over 80 mph
253,000*
Fourth Regular Enforcement Period
# Over 80 mph
158,033**
% Over 80 mph
8.57*
% Over 80 mph
5.25**
Result: 38.74% Reduction in Drivers Traveling over 80 mph
*Numbers adjusted to account for limited availability of data from Tube 06 (one week only—as opposed to
four weeks for ATR-175, ATR-191, and ATR-227): Also, data from Tube 06 are from the month prior to
the MSMP, data for ATR-175 and ATR-227 are from one year earlier, and data for ATR-191 are from two
years earlier.
** Numbers adjusted to account for limited availability of data from Tube 06 and ATR-227 (both one week
from all lanes), and ATR-191 (four weeks from Northbound lanes only)—as opposed to four weeks from
all lanes for ATR-175.
Table 2.12 indicates that, for the Tube and three of the four ATRs located Within
Enhanced Enforcement Zones on Rural Freeways, during the Fourth Regular
Enforcement Period, there was a 38.74% decrease in the number of drivers traveling over
80 mph—i.e., 10 mph over the speed limit.
We also examined the difference between the speed data obtained during the Test Periods
from the ATR that was located Outside the Enhanced Enforcement Zones. We focused
on drivers traveling at 80 mph or more—10 mph above the speed limit. The results of
this comparison for speed data obtained during the Fourth Enhanced Enforcement Period
are shown in Table 2.13.
Table 2.13: Effect of the MSMP on One ATR Outside the Enhanced Enforcement
Zones on a Rural Freeway During Fourth Enhanced Enforcement Period
Pre-MSMP Speed Data from 4/24/05 to 5/21/05
Sample Total
# Over 80 mph
% Over 80 mph
2,646,530
383,625
14.49
Fourth Enhanced Enforcement Period
Sample Total
# Over 80 mph
% Over 80 mph
2,567,419
96,765
3.77
Result: 73.98% Reduction in Drivers Traveling over 80 mph
Table 2.13 shows that, for the ATR located Outside Enhanced Enforcement Zones on a
Rural Freeway, during the Fourth Enhanced Enforcement Period, there was a 73.98%
decrease in the number of drivers traveling over 80 mph.
A5-18
A similar comparison was conducted for the Fourth Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 2.14.
Table 2.14: Effect of the MSMP at one ATR Outside the Enhanced Enforcement
Zones on a Rural Freeway During Fourth Regular Enforcement Period
Sample Total
1,297,731
Sample Total
336,601
One Year Before MSMP
# Over 80 mph
125,804
Fourth Regular Enforcement Period
# Over 80 mph
13,158
% Over 80 mph
9.69
% Over 80 mph
3.91
Result: 59.65% Reduction in Drivers Traveling over 80 mph
Table 2.14 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
a Rural Freeway, during the Fourth Regular Enforcement Period there was a 59.65%
decrease in the number of drivers traveling over 80 mph.
For Rural Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
Zones should be treated with caution. It should be noted that the ATR Outside the
Enhanced Enforcement Zones is located between two Enhanced Enforcement Zones on
the same freeway—one to the North-West; the other to the South-East. It is likely that
most drivers passing this ATR will have traveled through one or other of these Enhanced
Enforcement Zones. [It should also be noted that there are no other ATRs Outside the
Enhanced Enforcement Zones on Rural Freeways that could have been considered for
comparison purposes for this study.]
2.5. Effect of the MSMP on Urban Freeways
In the MSMP, we obtained speed data from four ATRs located on Urban Freeways—
three of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining ATR was located Outside the Enhanced Enforcement Zones. The speed limit
was increased from 55 mph to 60 mph at the locations of the three ATRs Within
Enhanced Enforcement Zones, while the speed limit remained unchanged at 55 mph at
location of the ATR Outside the Enhanced Enforcement Zones.
In order to provide a brief overall summary of the effect of the MSMP, speed data from
the three ATRs Within Enhanced Enforcement Zones were combined. For this summary,
we focused on drivers traveling at least 10 mph above the new speed limit. Then, we
compared speed data collected during the Fourth Enhanced Enforcement Period with preMSMP speed data collected just before the MSMP began—these data were collected over
two weeks in September 2005 for ATR-100, and over four weeks in August and
A5-19
September 2005 for ATR-I94 and ATR-35WCD. When the pre-MSMP data were
collected the speed limit at the locations of the three ATRs was still 55 mph. Table 2.15
shows the results of this comparison for the Fourth Enhanced Enforcement Period.
Table 2.15: Effect of the MSMP at Three ATRs Within Enhanced Enforcement
Zones on Urban Freeways During the Fourth Enhanced Enforcement Period
Sample Total
8,619,318*
Sample Total
17,163,656
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879*
Fourth Enhanced Enforcement Period
# Over 70 mph
1,915,980
% Over 70 mph
12.67*
% Over 70 mph
11.16
Result: 11.92% Reduction in Drivers Traveling over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-100 (for two weeks only—as
opposed to four weeks for both ATR-I94 and ATR-35WCD) during the pre-MSMP time period.
Table 2.14 indicates for the three ATRs Within Enhanced Enforcement Zones on Urban
Freeways, during the Fourth Enhanced Enforcement Period, there was a 11.92% decrease
in the number of drivers traveling over 70 mph—i.e., 10 mph over the new speed limit—
as compared to the month before the MSMP was implemented.
A similar comparison was conducted for the Fourth Regular Enforcement Period. The
results of this comparison using speed data from the three ATRs are shown in Table 2.16.
Table 2.16: Effect of the MSMP at Three ATRs Within Enhanced Enforcement
Zones on Urban Freeways During the Fourth Regular Enforcement Period
Sample Total
8,619,318*
Sample Total
8,758,094
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879*
Fourth Regular Enforcement Period
# Over 70 mph
1,016,161
% Over 70 mph
12.67*
% Over 70 mph
11.60
Result: 8.45% Reduction in Drivers Traveling over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-100 (for two weeks only—as
opposed to four weeks for both ATR-I94 and ATR-35WCD) during the pre-MSMP time period.
Table 2.16 indicates that, for the three ATRs located Within Enhanced Enforcement
Zones on Urban Freeways, during the Fourth Regular Enforcement Period, there was a
8.45% decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the
new speed limit—as compared to the month before the MSMP was implemented.
A5-20
We also examined the difference between the speed data obtained during the Test Periods
from the ATR that was located Outside the Enhanced Enforcement Zones. For this ATR
location there was no change in the level of enforcement during the MSMP and no
change in the speed limit. For comparison purposes, we focused on drivers traveling at
70 mph or more—while this is 10 mph above the new speed limit Within Enhanced
Enforcement Zones, it is 15 mph above the actual speed limit at the location of the ATR
Outside Enhanced Enforcement Zones. The results of this comparison for speed data
obtained during the Fourth Enhanced Enforcement Period with Pre-MSMP speed data are
shown in Table 2.17. It should be noted that, because of the unreliability of the data from
the prior year the Pre-MSMP data are from two years earlier.
Table 2.17: Effect of the MSMP at One ATR Outside the Enhanced Enforcement
Zones on an Urban Freeway During the Fourth Enhanced Enforcement Period
Sample Total
1,515,990*
Sample Total
1,336,806
Pre-MSMP
# Over 70 mph
902,413*
Fourth Enhanced Enforcement Period
# Over70 mph
769,009
% Over 70 mph
59.53*
% Over 70 mph
57.53
Result: 3.36% Reduction in Drivers Traveling over 70 mph
*Data for ATR-353 are from two years earlier.
Table 2.17 shows that, for the ATR located Outside Enhanced Enforcement Zones on an
Urban freeway, during the Fourth Enhanced Enforcement Period, there was a 3.36%
decrease in the number of drivers traveling over 70 mph—i.e., 10 mph above the new
speed limit Within Enhanced Enforcement Zones (and 15 mph above the current speed
limit Outside the Enhanced Enforcement Zones).
A similar comparison was conducted for the Fourth Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 2.18. Again, because of the unreliability of the
data from the prior year the Pre-MSMP data are from two years earlier.
Table 2.18: Effect of the MSMP at One ATR Outside the Enhanced Enforcement
Zones on an Urban Freeway During the Fourth Regular Enforcement Period
Sample Total
1,470,983*
Sample Total
1,405,127
Pre-MSMP
# Over 70 mph
925,333*
Fourth Regular Enforcement Period
# Over 70 mph
797,034
% Over 70 mph
62.91*
% Over 70 mph
56.72
Result: 9.84% Reduction in Drivers Traveling over 70 mph
*Data for ATR-353 are from two years earlier.
A5-21
Table 2.17 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
an Urban Freeway, during the Fourth Regular Enforcement Period there was a 9.84%
decrease in the number of drivers traveling over 70 mph—i.e., at 10 mph or more above
the new speed limit Within Enhanced Enforcement Zones (and 15 mph or more above the
current speed limit Outside Enhanced Enforcement Zones).
For Urban Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
Zones should be treated with caution. It should be noted that the location of ATR that
was located Outside the Enhanced Enforcement Zones is only a few miles to the North of
an Enforced Enforcement Zone. And, most of the drivers traveling North past this ATR
will have traveled through that Enhanced Enforcement Zone. [It should also be noted
that, the locations of all the other ATRs Outside the Enhanced Enforcement Zones on
Urban Freeways that might have been considered for comparison purposes for this study
are also very close to Enhanced Enforcement Zones.]
2.6. Crash Rates During the First, Second, and Fourth MSMP Periods
During the First, Second, and Fourth MSMP Test Periods, crash data were available for
all Minnesota trunk highways. These trunk highways included 2-Lane/2-Way Highways,
4-Lane Highways, Rural Freeways, and Urban Highways. Some of these highways had
changes in speed limits during the MSMP, some had enhanced enforcement during the
MSMP, and speed data were available from some of them. In all, there were twelve
combinations of Road Type, Speed Limits, and Enforcement Status. Table 2.18 lists the
Crash Rate, the Severity Rate, and the Fatal Crash Rate for each of these combinations
during the first 22 weeks of the MSMP.
A5-22
Table 2.18: Crash Rate, Severity Rate, and Fatal Crash Rate for Each Combination
of Trunk Highway Type, Speed Limits During the MSMP, and Enforcement Zone
During the 46 Weeks of the MSMP
Within
Road Type/Speed Limit
2 Lane/2-Way Highway
Increase—55 to 60 mph
2 Lane/2-Way Highway
No Change—55 mph
4 Lane/Divided Highway
No Change—65 mph
Rural Freeway
Unchanged—70 mph
Urban Freeway
Increase—55 to 60 mph
Urban Freeway
No Change—55 mph
Urban Freeway
No Change—60 mph
Outside
Crash
Rate
Severity
Rate
Fatal
Crash
Rate
Crash
Rate
Severity
Rate
Fatal
Crash
Rate
0.6537
1.0796
1.2381
0.4768
0.7176
0.9537
—
—
—
0.7370
1.1447
1.2076
0.5013
0.7273
0.3531
0.5954
0.8655
0.6432
0.5995
0.8266
0.4388
0.5185
0.7297
0.3278
0.8006
1.0848
0.2212
—
—
—
1.2047
1.5855
0.2151
1.2553
1.6116
0.3452
0.7437
1.0020
0.0000
0.8046
1.0536
0.1848
2.7. Citation Data During the Fourth Enhanced Enforcement Period
During the Fourth MSMP Enhanced Enforcement Period citation data were collected for
all the highways on which there was Enhanced Enforcement. These data are summarized
in Table 2.19. The table presents, for each of the four highway types in the MSMP, the
Number of Speed Citations and the Number of Speed Warnings that were given during
the Fourth Enhanced Enforcement Period, as well as the Number of Vehicles that were
Stopped and the Number of Hours of Enforcement.
Table 2.19: Citation Data for the Four Types of Highways on Which ATRs and
Tubes Were Located
Type of Highway
2-Lane/2-Way
Highway
4-Lane Divided
Highway
Rural Freeway
Urban Freeway
Total
Number of
Speed Citations
Number of
Speed Warnings
Number of
Vehicles
Stopped
1,110
3,547
5,078
812
1,149
2,276
1,441
1,903
1,508
2,441*
3,352
4,570
5,347
8,399
15,441
*Adjusted, but still probably an underestimate
A5-23
Hours of
Enforcement
Section 3. Speed Data Obtained on 2-Lane/2-Way Highways During the Fourth
Test Period
In the Fourth MSMP Period, we obtained speed data from seven ATRs and five Tubes
that were located on 2-Lane 2-Way Highways.
Three of the seven ATRs were located Within Enhanced Enforcement Zones, while the
remaining four were located Outside Enhanced Enforcement Zones. During the MSMP,
at the locations of the three ATRs Within the Enhanced Enforcement Zones, the speed
limit was increased from 55 mph to 60 mph and there was Enhanced Enforcement at
various times. In contrast, at the locations of the four ATRs Outside the Enhanced
Enforcement Zones, the speed limit remained unchanged at 55 mph and there was no
change in the enforcement level during the MSMP.
Four of the five Tubes were located Within Enhanced Enforcement Zones, while the
remaining Tube was located Outside the Enhanced Enforcement Zones. However, at all
five of the Tube locations—including the Tube located Outside the Enhanced
Enforcement Zones—the speed limit was increased from 55 mph to 60 mph.
In this section of the report, for the ATRs and Tubes located both Within and Outside the
Enhanced Enforcement Zones, we present comparisons of the speed data obtained during
the Fourth Test Period with the speed data obtained prior to the MSMP.
In making the comparisons between the speed data obtained during the Fourth Test
Period and the speed data obtained prior to the MSMP, we used two statistical tests. The
first test was used to examine differences in the mean speeds—for this we used the
procedure for comparing population means outlined by Kitchens (1987, p 369-373). The
second test was used to explore differences in the percentage of vehicles in the 10 mph
pace and in the differences in the proportions of vehicle traveling at various speeds. For
this test, we treated the distribution of speeds as a Bernoulli population—i.e., a
population in which each element is one of two possibilities, in this case, (1) in or out of
the 10 mph pace, or (2) above or below a selected speed (e.g., 75 mph). We then used the
procedure for comparing population proportions described by Kitchens (1987, pages 400404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
ATR in the time periods under consideration. Second, the tests were conducted using an
extremely conservative correction, with n-values equal to the number of hours in each
test period —the rationale for this was that it is possible, when traffic is congested, that
individual vehicles may travel at speeds which are not independent of each other.
A5-24
3.1. Speed Data Within the Enhanced Enforcement Zones
Three ATRs and four Tubes were located Within Enhanced Enforcement Zones on 2Lane 2-Way Highways. The locations of the ATRs were as follows: (1) ATR-210, on
US-71, near Blackduck in Beltrami County, (2) ATR-219, on US-2, near Warba in Itasca
County, and (3) ATR-220, on US-71, South of CR 89 in Hubbard County. The locations
of the Tubes were as follows: (1) T01, on MN-23, near Hanley Falls, in Lyon County, (2)
T02, on MN-7, near Montevideo, in Chippewa County, (3) T03, on US-71, near Willmar,
in Kandiyohi County, and (4) T04, on MN-7, near Silver Lake, in McLeod County.
Speed data from Tube 03 were collected only from the Southbound lane on US-71; while
speed data were collected from all lanes for the other three Tubes. At the locations of the
three ATRs and four Tubes, the speed limit was increased from 55 mph to 60 mph during
the MSMP.
The effect of the MSMP on the speed data at each of these ATRs and Tubes is reported in
this section. For each ATR, two tables are presented for both the Fourth Enhanced and
Regular Enhancement Periods; while for each Tube, there are two tables for both the
Fourth Regular Enhancement Periods. In the first of the tables, speed data from the Test
Year are compared with the available historical speed data. For the ATRs, if possible
historical speed data from the three years prior to the MSMP are included in this table—
however, in some cases, data were only available from one or two of the prior years.
Also in some cases, speed data are not available from the whole of the eight-week
Enhanced Enforcement Period or the whole of the four-week Regular Enhancement
Period—in these cases the dates from which the data are available are noted in the table.
For the Tubes, seven days of historical Pre-MSMP data, collected during August 2005,
were available. These historical Tube data are compared with seven days of speed data
that were collected from the Tubes during the Fourth Regular Enforcement Period
(between July 17 and July 24). In the second of the tables for each ATR and Tube, the
focus is on drivers traveling at least 5 mph and at least 10 mph above the new speed limit
adopted for the MSMP—i.e., on drivers traveling at 65 mph or more and at 70 mph or
more. In this second table, we present the number (and proportion) of vehicles traveling
above these speeds in the Test Period. We also present the average number of vehicles
traveling above these speeds every day. Then, the table presents the decrease in the
number of vehicles relative to the number that were traveling at these speeds before the
MSMP. It should be noted that, in each of three years before the MSMP was adopted,
these speeds (of 65 mph or more and 70 mph or more) were 10 mph and 15 mph above
the pre-MSMP speed limit.
A5-25
ATR-210—Enhanced Enforcement Period #4
Table 3.1 (a): ATR-210—Speed Data from the Fourth Enhanced Enforcement
Period Compared with Speed Data from the Three Previous Years
Decrease/
Increase as
Compared to Two
Years Earlier
Measure
(Three Weeks
Only
(5/22/06to
7/16/06)
Decrease/
Increase as
Compared to
One Year Earlier
(All Eight Weeks)
(All Eight Weeks)
Decrease/
Increase as
Compared to
Three Years
Earlier
(All Eight Weeks)
Mean (mph)
60.785410
-0.800978**
+0.612303**
-0.370882**
Percent in 10
mph pace
66.45665
+5.02591**
+5.90996**
+5.29483**
0.207595
-0.045504**
-0.026372*
-0.035456*
0.059733
-0.023639*
-0.018299*
-0.019040*
0.015612
-0.010635*
-0.008458*
-0.007356*
0.003960
-0.003242*
-0.002674*
-0.002091*
0.001697
-0.000952*
-0.000949*
ns
26,518
77,760
77,481
76,194
Test Period
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.1 (b): ATR-210—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Three Weeks
Only
(5/22/06to 7/16/06)
7.82385*
61.439853
55.765950
66.947590
68.638358
71.102991
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-26
Table 3.2 (a): ATR-210—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #4 and During the Previous Three
Years
Test Period
Measure
Number of vehicles
at 65 mph or more
Number of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
(Three
Weeks Only
(5/22/06to
7/16/06)
Daily
Average
in Test
Period
5,505
262
-57
-33
-45
1,584
75
-30
-23
-24
26,518
1,263
—
—
—
Table3.2 (b): ATR-210—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #4 and During the Previous Three Years
Test Period
Measure
Proportion of
vehicles at 65 mph
or more
Proportion of
vehicles at 70 mph
or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
(Three
Weeks Only
(5/22/06to
7/16/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.207595
0.207595
-0.045504
-0.026372
-0.035456
0.059733
0.059733
-0.023639
-0.018299
-0.019040
26,518
1,263
—
—
—
ATR-210—Regular Enforcement Period #4
No speed data were available for the Fourth Regular Enforcement Period.
A5-27
ATR-219—Enhanced Enforcement Period #4
Table 3.3 (a): ATR-219—Speed Data from the Fourth Enhanced Enforcement
Period Compared with Speed Data from the Three Previous Years
Measure
Test Period
(5/22/06to
7/16/06)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
61.545403
+0.190912**
-0.092917**
+0.001380*
Percent in 10
mph pace
77.55177
+1.71271*
+2.59193*
+7.71891**
0.147731
ns (+0.001173)
-0.011551*
-0.049773**
0.025727
-0.006310*
-0.009349*
-0.014150**
0.006310
-0.001383*
-0.002347*
-0.003989*
0.001711
ns
-0.000492*
-0.000801*
0.000615
ns
ns
-0.000286*
226,140
231,635
231,922
251,949
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.3 (b): ATR-219—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(5/22/06to 7/16/06)
5.52263*
61.981540
57.341182
64.980562
66.956144
69.005256
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-28
Table 3.4 (a): ATR-219—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #4 and During the Previous Three
Years
Measure
Number of vehicles
at 65 mph or more
Number of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(5/22/06to
7/16/06)
Daily
Average
in Test
Period
33,408
597
+5
-46
-201
5,818
104
-25
-38
-57
226,140
4,038
—
—
—
Table 3.4 (b): ATR-219—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #4 and During the Previous Three Years
Measure
Proportion of
vehicles at 65 mph
or more
Proportion of
vehicles at 70 mph
or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(5/22/06to
7/16/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.147731
0.147731
+0.001173
-0.011551
-0.049773
0.025727
0.025727
-0.006310
-0.009349
-0.014150
226,140
4,038
—
—
—
A5-29
ATR-219—Regular Enforcement Period #4
Table 3.5 (a): ATR-219—Comparison of Speed Data from the Fourth Regular
Enforcement Period Compared with Speed Data from the Three Previous Years
Measure
Test Period
(7/17/06 to
8/13/06)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
62.042887
+0.409785**
+0.033061**
+0.148475**
Percent in 10
mph pace
75.81607
ns (+0.00142)
+1.91348*
+7.78781**
0.181925
+0.027947*
ns (-0.002230)
-0.041280*
0.034181
ns (-0.001151)
-0.007592*
-0.015938*
0.007667
-0.001320**
-0.002302*
-0.005637*
0.001891
ns
-0.000547*
-0.001333*
0.000473
ns
-0.000202*
-0.000582*
118,428
124,732
125,894
135,517
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.5 (b): ATR-219—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to
8/13/06)
5.20099*
62.255486
57.785675
66.080414
67.772532
69.464651
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-30
Table 3.6 (a): ATR-219—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #4 and During the Previous Three Years
Measure
Number of vehicles
at 65 mph or more
Number of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(7/17/06 to
8/13/06)
Daily
Average
in Test
Period
21,545
769
+118
-9
-175
4,048
146
-5
-32
-67
118,428
4,230
—
—
—
Table 3.6 (b): ATR-219—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #4 and During the Previous Three Years
Measure
Proportion of
vehicles at 65 mph
or more
Proportion of
vehicles at 70 mph
or more
Vehicle Total
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(7/17/06 to
8/13/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One Year
Earlier
0.181925
0.181925
+0.027947
-0.002230
-0.041280
0.034181
0.034181
-0.001151
-0.007592
-0.015938
118,428
4,230
—
—
—
A5-31
ATR-220—Enhanced Enforcement Period #4
Table 3.7 (a): ATR-220—Speed Data from the Fourth Enhanced Enforcement
Period Compared with Speed Data from One Year Earlier
Measure
Test Period
(5/22/06to 7/16/06)
Decrease/Increase as
Compared to One
Year Earlier
Mean (mph)
61.127717
+0.227133**
Percent in 10 mph pace
74.83677
+1.45245*
0.151520
-0.003999*
0.036362
-0.005373*
0.007771
-0.001647*
0.002599
ns
0.000849
ns
149,663
158,958
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.7 (b): ATR-220—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(5/22/06to 7/16/06)
5.98597*
61.524933
56.546755
65.066014
67.236931
69.407847
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-32
Table 3.8 (a): ATR-220—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #4 with Speed Data from One Year
Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(5/22/06to 7/16/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
22,677
405
-11
5,442
97
-14
149,663
2,673
—
Table 3.8 (b): ATR-220—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #4 with Speed Data from Speed Data from One Year
Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(5/22/06to 7/16/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.151520
0.151520
-0.003999
0.036362
0.036362
-0.005373
149,663
2,673
—
A5-33
ATR-220—Regular Enforcement Period #4
Table 3.9 (a): ATR-220—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Speed Data from One Year Earlier
Measure
Test Period
(7/17/06 to 8/13/06)
Decrease/Increase as
Compared to
One Year Earlier
Mean (mph)
61.506214
+0.411394**
Percent in 10 mph pace
73.47999
+1.16803*
0.172480
+0.004756*
0.040942
-0.004769*
0.008860
-0.001869*
0.002739
ns
0.000917
ns
80,699
91,531
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.9 (b): ATR-220—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to
8/13/06)
5.83419*
61.798088
56.841946
65.854522
67.755111
69.655699
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-34
Table 3.10 (a): ATR-220—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #4 with Speed Data from One Year
Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(7/17/06 to 8/13/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
13,919
497
+14
3,304
118
-14
80,699
2,882
—
Table 3.10 (b): ATR-220—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #4 with Speed Data from Speed Data from One Year
Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(7/17/06 to 8/13/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to One
Year Earlier
0.172480
0.172480
+0.004756
0.040942
0.040942
-0.004769
80,699
2,882
—
A5-35
Tube 01—Regular Enforcement Period #4
Table 3.11 (a): Tube 01—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Pre-MSMP Speed Data from August 2005
Measure
Test Period
(7/17/06 to 7/24/06)
Decrease/Increase as
Compared to
Decrease/Increase
Compared to PreTest Period
(8/22/05 to 8/29/05)
Mean (mph)
60.717771
+0.392087**
Percent in 10 mph pace
83.12775
ns (-0.04839)
0.086022
ns (+0.000487)
0.019669
-0.003764*
0.006314
ns
0.002296
ns
26,133
25,861
Proportion at 65 mph or
more
Proportion at 70 mph or
more
Proportion at 75 mph or
more
Proportion at 80 mph or
more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.11 (b): Tube 01—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to
7/24/06)
4.40501*
60.853074
56.484635
64.359111
64.859974
67.714389
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-36
Table 3.12 (a): Tube 01—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #4 with Speed Data from the Pre-MSMP
Period in August 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(7/17/06 to 7/24/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Compared to Pre-Test
Period
(8/22/05 to 8/29/05)
2,248
321
+2
514
73
-14
26,133
3,733
—
Table 3.12 (b): Tube 01—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #4 with Speed Data from Speed Data from the PreMSMP Period in August 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(7/17/06 to 7/24/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Compared to Pre-Test
Period
(8/22/05 to 8/29/05)
0.086022
0.086022
+0.000487
0.019669
0.019669
-0.003764
26,133
3,733
—
A5-37
Tube 02—Regular Enforcement Period #4
Table 3.13 (a): Tube 02—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Pre-MSMP Speed Data from August 2005
Measure
Test Period
(7/17/06 to 7/24/06)
Decrease/Increase
Compared to Pre-Test
Period
(8/17/05 to 8/24/05)
Mean (mph)
59.027911
-0.759415**
Percent in 10 mph pace
74.36878
-1.51153*
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
0.062933
0.012343
0.003795
0.001105
0.0002948
-0.037902*
-0.007255*
-0.001398*
-0.000749*
ns
Vehicle Total
27,140‫٭‬
16,175‫٭‬
‫٭‬It should be noted that the vehicle totals are very different during the MSMP period and the Pre-MSMP
period—there were 67% more vehicles in the MSMP than in the Pre-MSMP period. We were unable to
discover why there was this difference in vehicle totals.
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.13 (b): Tube 02—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to
7/24/06)
5.53358*
59.355777
55.170089
63.863942
64.516346
66.278223
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-38
Table 3.14 (a): Tube 02—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #4 with Speed Data from the Pre-MSMP
Period in August 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(7/17/06 to 7/24/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(8/17/05 to 8/24/05)
1,708
244
-147
335
48
-28
27,140
3,877
—
Table 3.14 (b): Tube 02—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #4 with Speed Data from Speed Data from the PreMSMP Period in August 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(7/17/06 to 7/24/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Compared to Pre-Test
Period
(8/17/05 to 8/24/05)
0.062933
0.062933
-0.037902
0.012343
0.012343
-0.007255
27,140
3,877
—
A5-39
Tube 03—Regular Enforcement Period #4
Table 3.15 (a): Tube 03—Comparison of Speed Data from the Fourth Regular
Enforcement Period (Southbound Lanes Only) with Pre-MSMP Speed Data from
August 2005 (All Lanes)
Measure
(Southbound
Lanes Only)
Decrease/Increase
Compared to Pre-Test
Period
(8/17/05 to 8/24/05)
(All Lanes)
Mean (mph)
59.561421
-0.095190**
Percent in 10 mph pace
84.87117
+3.63623*
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
0.048439
0.005979
0.001273
0.000221
0.0001661
-0.019422*
-0.006641*
-0.002248*
-0.000905*
-0.000369*
Vehicle Total
18,064
35,499
Test Period
(7/17/06 to 7/24/06)
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.15 (b): Tube 03—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to
7/24/06)
(Southbound
Lanes Only)
4.55499*
59.649712
55.857486
63.788723
64.385052
64.981381
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-40
Table 3.16 (a): Tube 03—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #4 with Speed Data from the Pre-MSMP
Period in August 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(7/17/06 to 7/24/06)
(Southbound Lanes
Only)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(8/17/05 to 8/24/05)
(All Lanes)
875
125
-50
108
15
-17
18,064
2,580
—
Table 3.16 (b): Tube 03—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #4 with Speed Data from Speed Data from the PreMSMP Period in August 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(7/17/06 to 7/24/06)
(Southbound Lanes
Only)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(8/17/05 to 8/24/05)
(All Lanes)
0.048439
0.048439
-0.019422
0.005979
0.005979
-0.006641
18,064
2,580
—
A5-41
Tube 04—Regular Enforcement Period #4
Table 3.17 (a): Tube 04—Comparison of Speed Data from t the Fourth Regular
Enforcement Period (All Lanes) with Pre-MSMP Speed Data August (Westbound
Lane Only)
Measure
(All Lanes)
Decrease/Increase
Compared to Pre-Test
Period
(8/17/05 to 8/24/05)
(Westbound Lanes
Only)
Mean (mph)
59.073962
+0.772621**
Percent in 10 mph pace
78.14758
+0.026691*
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
0.053661
0.005352
0.001124
0.000392
0.0001427
+0.023285*
ns (+0.000611)
ns
ns
ns
Vehicle Total
56,056
32,065
Test Period
(7/17/06 to 7/24/06)
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.17 (b): Tube 04—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to
7/24/06)
4.78737*
59.087094
55.361098
63.664127
64.357443
65.378877
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-42
Table 3.18 (a): Tube 04—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #4 with Speed Data from the Pre-MSMP
Period in August 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(7/17/06 to 7/24/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Compared to Pre-Test
Period
(8/17/05 to 8/24/05)
(Westbound Lane
Only)
3,008
430
+186
300
43
+5
56,056
8,008
—
Table 3.18 (b): Tube 04—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #4 with Speed Data from Speed Data from the PreMSMP Period in August 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(7/17/06 to 7/24/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Compared to Pre-Test
Period
(8/17/05 to 8/24/05)
(Westbound Lane
Only)
0.053661
0.053661
+0.023285
0.005352
0.005352
+0.000611
56,056
8,008
—
A5-43
3.2. Speed Data from One Tube Located Outside Enhanced Enforcement Zones but in a
Zone with a Speed Limit Change
The speed limit was changed from 55mph to 60 mph at the location of the single Tube
that was on a 2-Lane/2-Way Highway Outside the Enhanced Enforcement Zones. It was
Tube 08 located on US-53, near Ash Lake, in St Louis County.
Seven days of speed data were collected (between July 18 and July 24) with this Tube
during the Fourth Regular Enforcement Period. These data were compared with seven
days of historical Pre-MSMP data collected at the same place during August 2005. Two
tables are presented for the Fourth Regular Enforcement Period. In the first table, speed
data from the Test Year are compared with historical speed data. In the second table, the
focus is on drivers traveling at least 5 mph and at least 10 mph above the new speed limit
adopted for the MSMP—i.e., on drivers traveling at 65 mph or more and at 70 mph or
more. In the second table, we present the number (and proportion) of vehicles traveling
above these speeds in the Fourth Regular Enforcement Period. We also present the
average number of vehicles traveling above these speeds every day. Then, the table
presents the decrease in the number of vehicles relative to the number that were traveling
at these speeds before the MSMP. It should be noted that, before the MSMP was
adopted, these speeds (of 65 mph or more and 70 mph or more) were 10 mph and 15 mph
above the pre-MSMP speed limit.
A5-44
Table 3.19 (a): Tube 08—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Pre-MSMP Speed Data from August 2005
Measure
Test Period
(7/18/06 to 7/24/06)
Decrease/Increase
Compared to Pre-Test
Period
(8/17/05 to 8/24/05)
Mean (mph)
61.873565
+0.279754**
Percent in 10 mph pace
71.51702
ns (-0.56632)
0.193920
+0.018545*
0.041954
ns (-0.000615)
0.010220
ns
Proportion at 65 mph or
more
Proportion at 70 mph or
more
Proportion at 75 mph or
more
Proportion at 80 mph or
more
Proportion at 85 mph or
more
0.002370
ns
0.0010368
ns
Vehicle Total
27,006
28,824
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.19 (b): Tube 08—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/18/06 to
7/24/06)
4.77293*
61.822480
56.911564
66.445054
68.090156
69.735258
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-45
Table 3.20 (a): Tube 08—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #4 with Speed Data from the Pre-MSMP
Period in August 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(7/18/06 to 7/24/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Decrease/Increase
Compared to Pre-Test
Period
(8/19/05 to 8/26/05)
5,237
748
+72
1,133
162
-2
27,006
3,858
—
Table 3.20 (b): Tube 08—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #4 with Speed Data from Speed Data from the PreMSMP Period in August 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(7/18/06 to 7/24/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to
Compared to Pre-Test
Period
(8/19/05 to 8/26/05)
0.193920
0.193920
+0.018545
0.041954
0.041954
-0.000615
27,006
3,858
—
A5-46
3.3. Speed Data from ATRs located Outside Enhanced Enforcement Zones and in Zones
with No Change in Speed Limit
There were four ATRs located Outside Enhanced Enforcement Zones on 2-Lane 2-Way
Highways. These ATRs were as follows—(1) ATR-179, on USTH 59, near Garvin, in
Lyon County, (2) ATR-198, on USTH 212, East of TH 23, in Chippewa County, (3)
ATR-199, on USTH 75, North of CR 69, in Pipestone County, and ATR-222, on MNTH
65, near Pliny, in Aitkin County. During the MSMP, at the locations of the ATRs located
Outside Enhanced Enforcement Zones, speed limits remained unchanged—at 55 mph—
and there were no changes in enforcement. For each of these ATRs, the speed data
obtained during 2005, when the MSMP occurred, were compared with the historical
speed data. These comparisons are reported site by site, first for the eight-week time
period between 5/22 and 7/16, when the Fourth Enhanced Enforcement Period occurred,
and then for the four-week time period between 7/17 and 8/13, when the Fourth Regular
Enhancement Period occurred.
For each of the four ATRs located Outside Enhanced Enforcement Zones two tables are
presented for each time period. In the first table, speed data from the Test Year are
compared with the historical speed data. We include speed data from the three years
prior to the MSMP in the table, whenever possible—it should be noted that in some cases
data are only available from one or two prior years. Also in some cases, speed data are
not available from the whole of the Fourth Enhanced Enforcement Period or the Fourth
Regular Enhancement Period—in these cases the dates from which the data are available
are noted in the table. In the second of these tables for each of the ATRs located Outside
Enhanced Enforcement Zones, the focus is on drivers traveling at least 5 mph and at least
10 mph above the new speed limit adopted for the MSMP—i.e., drivers traveling at least
65 mph and at least 70 mph). It should be noted that during the MSMP, as well as during
the three years before it was adopted, these speeds (of at least 65 mph and at least 70
mph) were 10 mph and 15 mph above the actual speed limit at the locations of the four
ATRs located Outside Enhanced Enforcement Zones. In this second table, we present the
number and proportion of vehicles traveling above these speeds throughout the Fourth
Enhanced Enforcement Period or the Fourth Regular Enhancement Period. We also
present the average number of vehicles traveling above these speeds every day. Then, the
table presents the decrease in the number of vehicles relative to the number that were
traveling at these speeds before the Test Year.
A5-47
ATR-179—Enhanced Enforcement Period #4
Table 3.21 (a): ATR-179—Comparison of Speed Data from the Fourth Enhanced
Enforcement Period with Speed Data from One Year Earlier
Decrease/Increase as
Compared to One Year
Earlier
Measure
Test Period
(Five Weeks Only
05/22/06 to 06/11/06
and
07/03/06 to 07/16/03)
Mean (mph)
55.459037
+0.615843**
Percent in 10 mph pace
69.11028
+1.81467*
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
0.014090
0.002861
0.000733
0.000284
0.000106
-0.001471*
ns (-0.000080)
ns
ns
ns
Vehicle Total
84,601
139,775
(All Eight Weeks)
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.21 (b): ATR-179—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Five Weeks Only
(05/22/06 to 06/11/06
and
07/03/06 to 07/16/03)
6.62809*
56.248759
50.680868
61.079998
62.522126
63.964254
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-48
Table 3.22 (a): ATR-179—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #4 with Speed Data from One Year
Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
Five Weeks Only
(05/22/06 to 06/11/06
and
07/03/06 to 07/16/03)
Daily
Average in
Test Period
Decrease/
Increase
Compared to One
Year Earlier
1,192
34
-4
242
7
0
84,601
2,417
—
Table 3.22 (b): ATR-179—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #4 with Speed Data from Speed Data from One Year
Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
Five Weeks Only
(05/22/06 to 06/11/06
and
07/03/06 to 07/16/03)
Daily
Average in
Test Period
Decrease/
Increase
Compared to One
Year Earlier
0.014090
0.014090
-0.001471
0.002861
0.002861
-0.000080
84,601
2,417
—
A5-49
ATR-179—Regular Enforcement Period #4
Table 3.23 (a): ATR-179—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Speed Data from One Year Earlier
Measure
Test Period
(7/17/06 to 8/13/06)
Decrease/Increase as
Compared to One
Year Earlier
Mean (mph)
55.663263
+0.323379**
Percent in 10 mph pace
69.07970
+2.38058
0.014997
-0.004130*
0.002591
-0.000829*
0.000518
-0.000287*
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.000152
ns
0.0000457
ns
Vehicle Total
65,615
69,590
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.23 (b): ATR-179—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to
8/13/06)
6.49920*
56.407322
50.876922
61.250635
62.639253
64.027872
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-50
Table 3.24 (a): ATR-179—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #4 with Speed Data from One Year
Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(7/17/06 to 8/13/06)
Daily
Average in
Test Period
Decrease/
Increase
Compared to One
Year Earlier
984
35
-10
170
5
-2
65,615
2,343
—
Table 3.24 (b): ATR-179—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #4 with Speed Data from Speed Data from One Year
Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(7/17/06 to 8/13/06)
Daily
Average in
Test Period
Decrease/
Increase
Compared to One
Year Earlier
0.014997
0.014997
-0.004130
0.002591
0.002591
-0.000829
65,615
2,343
—
A5-51
ATR-198—Enhanced Enforcement Period #4
Table 3.25 (a): ATR-198—Comparison of Speed Data from the Fourth Enhanced
Enforcement Period with Speed Data from the Three Previous Years
Measure
(Five Weeks Only
5/22/06 to 6/11/06
and
7/03/06 to 7/16/06)
Decrease/
Increase as
Compared to
One Year
Earlier
(All Eight Weeks)
Decrease/
Increase as
Compared to
Two Years
Earlier
(All Eight Weeks)
Decrease/
Increase as
Compared to
Three Years
Earlier
(All Eight Weeks)
Mean (mph)
58.159911
+0.201007**
-0.361206**
-0.376239**
Percent in 10 mph
pace
59.90975
-2.23017*
-7.84618**
-5.21330**
0.108801
+0.039241**
+0.030358**
+0.024419*
0.051485
+0.037637**
+0.033943**
+0.033019**
0.008889
+0.006296**
+0.006077*
+0.005324*
0.005861
+0.005156**
+0.004905**
+0.004792**
0.004598
+0.004379**
+0.004269**
+0.004267**
97,426
150,418
161,098
145,020
Test Period
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.25 (b): ATR-198—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Five Weeks Only
(05/22/06 to 06/11/06
and
07/03/06 to 07/16/03)
9.45008*
59.347553
52.429443
64.405313
65.767729
70.174337
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-52
Table 3.26 (a): ATR-198—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #4 and During the Previous Three
Years
Measure
Number of vehicles
at 65 mph or more
Number of vehicles
at 70 mph or more
Vehicle Total
Test Period
(Five Weeks
Only
5/22/06 to
6/11/06
and
7/03/06 to
7/16/06)
Daily
Average
in Test
Period
10,600
303
+109
+85
+68
5,016
143
+104
+94
+92
97,426
2,784
—
—
—
Decrease/
Decrease/
Increase
Increase
Compared
Compared to
to One
Two Years
Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
Table 3.26 (b): ATR-198—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #4 and During the Previous Three Years
Measure
Proportion of
vehicles at 65 mph
or more
Proportion of
vehicles at 70 mph
or more
Vehicle Total
Test Period
(Five Weeks
Only
5/22/06 to
6/11/06
and
7/03/06 to
7/16/06)
Daily
Average in
Test Period
Decrease/
Decrease/
Increase
Increase
Compared to Compared to
Two Years
One Year
Earlier
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.108801
0.108801
+0.039241
+0.030358
+0.024419
0.051485
0.051485
+0.037637
+0.033943
+0.033019
97,426
2,784
—
—
—
A5-53
ATR-198—Regular Enforcement Period #4
Table 3.27(a): ATR-198—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Speed Data from the Three Previous Years
Measure
Test Period
(7/17/06 to
8/13/06)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease
/Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
58.336905
+0.765690**
-0.509080**
-0.385064**
Percent in 10 mph
pace
61.43262
+2.31780*
-5.67791**
-4.18890*
0.108085
+0.037130**
+0.018717*
+0.015494*
0.038844
+0.023861**
+0.019612**
+0.018751**
0.009534
+0.006312*
+0.00586*
+0.005963*
0.002529
+0.001542*
+0.001573*
+0.001610*
0.001909
+0.001567*
+0.001663*
+0.00155*
79,086
72,948
73,214
75,051
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.27 (b): ATR-198—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to
8/13/06)
8.96072*
59.582545
52.977818
64.423395
65.583820
69.194394
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-54
Table 3.28 (a): ATR-198—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #4 and During the Previous Three Years
Decrease/
Measure
Number of vehicles
at 65 mph or more
Number of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Increase
Test Period
(7/17/06 to
8/13/06)
Daily
Average
in Test
Period
Compared
to One
Year
Earlier
Compared
to Two
Years
Earlier
Compared
to Three
Years
Earlier
8,548
305
+105
+53
+44
3,072
108
+67
+55
+53
79,086
2,825
—
—
—
Table 3.28 (b): ATR-198—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #4 and During the Previous Three Years
Measure
Proportion of
vehicles at 65 mph
or more
Proportion of
vehicles at 70 mph
or more
Vehicle Total
Decrease/
Decrease/
Decrease/
Increase
Increase
Increase
Test Period
(7/17/06 to
8/13/06)
Daily
Average
in Test
Period
Compared
to One
Year
Earlier
Compared
to Two
Years
Earlier
Compared
to Three
Years
Earlier
0.108085
0.108085
+0.037130
+0.018717
+0.015494
0.038844
0.038844
+0.023861
+0.019612
+0.018751
79,086
2,825
—
—
—
A5-55
ATR-199—Enhanced Enforcement Period #4
Table 3.29 (a): ATR-199—Comparison of Speed Data from the Fourth Enhanced
Enforcement Period with Speed Data from Two Earlier Years
Measure
Test Period
(5/22/06to
7/16/06)
Decrease/
Increase as
Compared to
Two Years
Earlier
(Four Weeks Only)
Decrease/
Increase as
Compared to
Three Years
Earlier
(All Eight Weeks)
Mean (mph)
58.679886
-0.662167**
+0.001089*
Percent in 10
mph pace
72.81959
-1.6682*
+2.39447*
0.065320
-0.023738*
-0.020671**
0.018663
-0.007022*
-0.006013*
0.005375
-0.001267*
-0.002512*
0.002116
ns
ns
0.001041
ns
ns
87,447
45,319
90,533
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.29 (b): ATR-199—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(5/22/06to 7/16/06)
5.90063*
58.713686
54.781568
63.657094
64.450020
66.641728
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-56
Table 3.30 (a): ATR-199—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #4 and Speed Data from Two and
Three Years Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(5/22/06to
7/16/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
5,712
102
-37
-32
1,632
29
-11
-9
87,447
1,562
—
—
Table 3.30 (b): ATR-199—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #4 and Speed Data from Two and Three Years
Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Test Period
(5/22/06to
7/16/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.065320
0.065320
-0.023738
-0.020671
0.018663
0.018663
-0.007022
-0.006013
A5-57
ATR-199—Regular Enforcement Period #4
Table 3.31 (a): ATR-199—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Speed Data from Two Previous Years
Measure
Test Period
(7/17/06 to 8/13/06)
Decrease/
Increase as
Compared to
Two Years
Earlier
Mean (mph)
59.011770
-0.483018**
+0.188328**
Percent in 10
mph pace
74.45900
-0.60378*
+3.74517*
0.072021
-0.022583*
-0.019847*
0.020349
-0.006172*
-0.005706*
0.005873
ns
-0.002198*
0.002199
ns
ns
0.000991
ns
ns
41,377
44,417
50,431
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
Decrease/
Increase as
Compared to
Three Years
Earlier
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.31 (b): ATR-199—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to
8/13/06)
5.71228*
58.971919
55.117261
63.834844
64.581937
67.130847
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-58
Table 3.32 (a): ATR-199—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #4 and Speed Data from Two and Three
Years Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(7/17/06 to
8/13/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
2,980
106
-33
-29
842
30
-9
-8
41,377
1,478
—
—
Table 3.32 (b): ATR-199—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #4 and Speed Data from Two and Three Years Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(7/17/06 to
8/13/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.072021
0.072021
-0.022583
-0.019847
0.020349
0.020349
-0.006172
-0.005706
41,377
1,478
—
—
A5-59
ATR-222—Enhanced Enforcement Period #4
Table 3.33 (a): ATR-222—Comparison of Speed Data from the Fourth Enhanced
Enforcement Period with Speed Data from the Three Previous Years
Measure
Test Period
(5/22/06to
7/16/06)
Decrease/
Increase as
Compared to
One Year
Earlier
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
61.546291
-0.137132**
-0.401834**
-0.658751**
Percent in 10
mph pace
48.60979
-18.24896**
-17.09925**
-17.18327**
0.338313
+0.112481**
+0.090925**
+0.075898**
0.141458
+0.077804**
+0.076085**
+0.073396**
0.052965
+0.034316**
+0.033053**
+0.031960**
0.019845
+0.014987**
+0.014856**
+0.014288**
0.006522
+0.004568*
+0.004747*
+0.004365*
124,970
131,540
134,093
141,444
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.33 (b): ATR-222—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(5/22/06to 7/16/06)
9.97358*
61.630986
54.844522
69.783037
72.342436
75.447572
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-60
Table 3.34 (a): ATR-222—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #4 and During the Previous Three
Years
Decrease/
Measure
Number of vehicles
at 65 mph or more
Number of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Increase
Test Period
(5/22/06to
7/16/06)
Daily
Average
in Test
Period
Compared
to One
Year
Earlier
Compared
to Two
Years
Earlier
Compared
to Three
Years
Earlier
42,279
755
+251
+203
+169
17,678
316
+174
+170
+164
124,970
2,232
—
—
—
Table 3.34 (b): ATR-222—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #4 and During the Previous Three Years
Measure
Proportion of
vehicles at 65 mph
or more
Proportion of
vehicles at 70 mph
or more
Vehicle Total
Decrease/
Decrease/
Decrease/
Increase
Increase
Increase
Test Period
(5/22/06to
7/16/06)
Daily
Average
in Test
Period
Compared
to One
Year
Earlier
Compared
to Two
Years
Earlier
Compared
to Three
Years
Earlier
0.338313
0.338313
+0.112481
+0.090925
+0.075898
0.141458
0.141458
+0.077804
+0.076085
+0.073396
124,970
2,232
—
—
—
A5-61
ATR-222—Regular Enforcement Period #4
Table 3.35 (a): ATR-222—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Speed Data from Two Earlier Years
Measure
Test Period
(Two Weeks Only
7/17/06 to 7/30/06)
Decrease/
Increase as
Compared to Two
Years Earlier
(All Four Weeks)
Decrease/
Increase as
Compared to Two
Years Earlier
(All Four Weeks0
Mean (mph)
61.898907
-0.091301**
-0.502793**
Percent in 10 mph
pace
47.48905
-18.40021**
-17.42921**
0.352969
+0.106841**
+0.075316**
0.149201
+0.082082**
+0.071320**
0.054870
+0.033428**
+0.029562**
0.023751
+0.017944**
+0.016971**
0.006829
+0.004562*
+0.004491*
29,725
68,371
68,438
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 3.35 (b): ATR-222—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Two Weeks Only
7/17/06 to 7/30/06)
9.65766*
61.791116
55.066132
69.980395
72.607882
75.782432
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-62
Table 3.36 (a): ATR-222—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #4 and Speed Data from Two and Three
Years Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
10,492
749
+227
+160
4,435
317
+174
+151
29,725
2,123
—
—
Test Period
(Two Weeks
Only
7/17/06 to
7/30/06)
Table 3.36 (b): ATR-222—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #4 and Speed Data from Two and Three Years Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.352969
0.352969
+0.106841
+0.075316
0.149201
0.149201
+0.082082
+0.071320
29,725
2,123
—
—
Test Period
(Two Weeks
Only
7/17/06 to
7/30/06)
3.4 Overall Effect of MSMP on 2-Lane 2-Way Highways
In the MSMP, we obtained speed data from seven ATRs and five Tubes located on 2Lane 2-Way Highways—although the Tube data were collected only in the Fourth
Regular Enforcement Period. Three of the ATRs and four of the Tubes were located
Within Enhanced Enforcement Zones: The speed limit was increased from 55 mph to 60
mph at the locations of these three ATRs and four Tubes. The fifth Tube was located
Outside the Enhanced Enforcement Zones but it was on a road where the speed limit was
increased from 55 mph to 60 mph. In contrast, the four remaining ATRs were located
Outside Enhanced Enforcement Zones and on roads where the speed limit remained
unchanged at 55 mph.
A5-63
In order to provide a brief overall summary of the effect of the MSMP during the Fourth
Enhanced Enforcement Period, we focused on drivers traveling at least 10 mph above the
new speed limit. Speed data from the three ATRs Within Enhanced Enforcement Zones
were combined. Then, we compared speed data from the Test Year with data from the
previous year, when the speed limit at the locations of the ATRs was still 55 mph. Table
3.37 presents the results of this comparison for the Fourth Enhanced Enforcement Period.
Table 3.37: Effect of the MSMP on 2-Lane 2-Way Highways during the Fourth
Enhanced Enforcement Period at Three ATRs Within Enhanced Enforcement Zones
Sample Total
468,353
Sample Total
446,518*
One Year Before MSMP
# Over 70 mph
20,538
Fourth Enhanced Enforcement Period
# Over 70 mph
15,484*
% Over 70 mph
4.39
% Over 70 mph
3.47*
Result: 20.96% Reduction in Drivers Traveling Over 70 mph
*Numbers adjusted to account for limited availability of speed data from ATR-210 (three weeks—as
opposed to eight weeks for ATR-219 and ATR-220) during the time period.
Table 3.37 indicates that at the locations of the three ATRs Within Enhanced
Enforcement Zones on 2-Lane 2-Way Highways, during the Fourth Enhanced
Enforcement Period, there was a 20.96% decrease in the number of drivers traveling over
70 mph—i.e., 10 mph over the new speed limit.
A similar comparison was conducted for the Fourth Regular Enforcement Period. In this
case, however, no speed data were available from ATR-210, although speed data were
available from the four Tubes. The speed data from the Tubes and from the two ATRs
were combined. Then, we compared speed data from the Test Year with Pre-MSMP
speed data, when the speed limit at the locations of the ATRs and Tubes was still 55 mph.
It should be noted that the speed data that were used for comparison purposes for the two
ATRs were obtained in the same calendar time period one year earlier, while the
comparison data for the Tubes were obtained in August 2005, just before the beginning
of the MSMP. Table 3.38 shows the results of this comparison for the Fourth Regular
Enforcement Period.
A5-64
Table 3.38: Effect of the MSMP on 2-Lane 2-Way Highways during Fourth Regular
Enforcement Period at Two ATRs and Four Tubes Within Enhanced Enforcement
Zones
Sample Total
782,923*
Sample Total
780,955**
Pre-MSMP
# Over 70 mph
15,291*
Fourth Regular Enforcement Period
# Over 70 mph
12,812**
% Over 70 mph
1.95*
% Over 70 mph
1.64**
Result: 15.90% Reduction in Drivers Traveling Over 70 mph
*Numbers adjusted to account for limited availability of speed data from Tube 01, Tube 02 and Tube 03
(all one week) and Tube 04 (one week and Westbound lane only)—as compared to ATR-219 and ATR-220
(both four weeks)
**Numbers adjusted to account for limited availability of speed data from Tube 01, Tube 02 and Tube 04
(all one week) and Tube 03 (one week and Southbound lane only)—as compared to ATR-219 and ATR220 (both four weeks)
Table 3.38 shows that, during the Fourth Regular Enforcement Period, at the locations of
the two ATRs and four Tubes Within Enhanced Enforcement Zones on 2-Lane 2-Way
Highways, there was a 15.90% reduction in the number of drivers traveling over 70
mph—i.e., 10 mph over the speed limit.
For the Fourth Regular Enforcement Period, a similar comparison was conducted for the
speed data obtained at the location of the single Tube (Tube 05) that was on a 2-Lane/2Way Highway where the speed limit was changed from 55mph to 60 mph, but was
Outside the Enhanced Enforcement Zones. We compared speed data from the Test Year
with data obtained in August 2005, just before the beginning of the MSMP, when the
speed limit at the location of the Tube was still 55 mph. Table 3.39 shows the results of
this comparison for the Fourth Regular Enforcement Period.
Table 3.39: Effect of the MSMP on 2-Lane 2-Way Highways during Fourth Regular
Enforcement Period at One Tube that Was Outside Enhanced Enforcement Zones
but Where There Was a Change in Speed Limit
Sample Total
28,824
Sample Total
27,006
Pre-MSMP
# Over 70 mph
1,227
Fourth Regular Enforcement Period
# Over 70 mph
1,133
% Over 70 mph
4.26
% Over 70 mph
4.20
Result: 1.41% Reduction in Drivers Traveling Over 70 mph
Table 3.39 shows that, during the Fourth Regular Enforcement Period, for the Tube
located Outside Enhanced Enforcement Zones on a 2-Lane 2-Way Highway, but where
A5-65
there was a change in speed limit, there was a 1.41% decrease in the number of drivers
traveling over 70 mph—i.e., 10 mph above the new speed limit and 15 mph above the
previous speed limit at this location.
We also examined the speed data obtained during the Test Periods from the four ATRs
Outside Enhanced Enforcement Zones, where there was no change in the level of
enforcement during the MSMP and no change in the speed limit. We compared this data
with speed data from the previous year, focusing on drivers traveling at 70 mph or
more—while this is 10 mph above the new speed limit Within Enhanced Enforcement
Zones, it is 15 mph above the actual speed limit at the locations of the four ATRs Outside
Enhanced Enforcement Zones. The results of this comparison for speed data obtained
during the Fourth Enhanced Enforcement Period are shown in Table 3.40.
Table 3.40: Effect of the MSMP on 2-Lane 2-Way Highways during the Fourth
Enhanced Enforcement Period at Four ATRs Outside Enhanced Enforcement Zones
Sample Total
512,597*
Sample Total
503,661**
Pre-MSMP
# Over 70 mph
13,195*
Fourth Enhanced Enforcement Period
# Over 70 mph
27,723**
% Over 70 mph
2.58%
% Over 70 mph
5.50**
Result: 113.18 Increase in Drivers Traveling Over 70 mph
*Numbers adjusted to account for limited availability of speed data from ATR-199 (4 weeks—as opposed
to 8 weeks for ATR-179, ATR-199, and ATR-222) during the time period; also, speed data from ATR-179,
ATR-198, and ATR-222 are from one year earlier, while data from ATR-199 are from two years earlier
**Numbers adjusted to account for limited availability of speed data from ATR-179 & ATR-198 (both 5
weeks—as opposed to 8 weeks for ATR-199 and ATR-222) during the time period.
Table 3.40 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on 2-Lane 2-Way Highways, during the Fourth Enhanced Enforcement Period, there was
a 113.18% increase in the number of drivers traveling over 70 mph—i.e., 10 mph above
the new speed limit Within Enhanced Enforcement Zones (and 15 mph above the current
speed limit Outside the Enhanced Enforcement Zones). It should be noted that the large
increase seen in the numbers of vehicles traveling over 70 mph indicated in Table 3.40 is
entirely due to the data from two of the ATRs (ATR-198 and ATR-222).
A similar comparison was conducted for the Fourth Regular Enforcement Period. The
results of this comparison using speed data from the four ATRs located Outside
Enhanced Enforcement Zones are shown in Table 3.41.
A5-66
Table 3.41: Effect of the MSMP on 2-Lane 2-Way Highways during the Fourth
Regular Enforcement Period at Four ATRs Outside Enhanced Enforcement Zones
Sample Total
255,326*
Sample Total
245,528**
Pre-MSMP
# Over 70 mph
7,098*
Fourth Regular Enforcement Period
# Over 70 mph
12,954**
% Over 70 mph
2.78*
% Over 70 mph
5.28**
Result: 89.93 Increase in Drivers Traveling over 70 mph
*Speed data from ATR-179 and ATR-198 are from one year earlier, while data from ATR-199 and ATR222 are from two years earlier
** Numbers adjusted to account for limited availability of speed data from ATR-222 (two weeks—as
opposed to four weeks for ATR-179, ATR-198, and ATR-199) during the time period.
Table 3.41 shows that, for the four ATRs located Outside Enhanced Enforcement Zones
on the 2-Lane 2-Way Highways, during the Fourth Regular Enforcement Period there
was a 89.93% increase in the number of drivers traveling over 70 mph—i.e., at 10 mph
over the new speed limit Within Enhanced Enforcement Zones (and 15 mph above the
current speed limit Outside Enhanced Enforcement Zones). Again, it should be noted
that the large increase seen in the numbers of vehicles traveling over 70 mph indicated in
Table 3.41 is entirely due to the data from two of the ATRs (ATR-198 and ATR-222).
Comparisons between speed data from the ATRs and Tubes located Within Enhanced
Enforcement Zones and the ATRs located Outside Enhanced Enforcement Zones should
be treated with caution.
A5-67
Section 4. Speed Data Obtained on 4-Lane Divided Highways
We obtained speed data from five ATRs and one Tube located on 4-Lane Divided
Highways. The Tube and four of the ATRs were located Within Enhanced Enforcement
Zones, while the remaining ATR was located Outside the Enhanced Enforcement Zones.
At the locations of the four ATRs Within the Enhanced Enforcement Zones and the ATRs
Outside the Enhanced Enforcement Zones, the speed limit was unchanged—remaining at
65mph—during the MSMP.
For the three ATRs and the Tube located Within Enhanced Enforcement Zones and the
ATR located Outside Enhanced Enforcement Zones, we present comparisons of the speed
data obtained during the Test Year with the speed data obtained prior to the MSMP.
First, we present comparisons using the speed data from the ATRs and the Tube located
Within Enhanced Enforcement Zones, then comparisons using the speed data from the
ATR located Outside the Enhanced Enforcement Zones.
In making the comparisons between the speed data obtained during the Test Year and
prior to the MSMP, we used two statistical tests. The first test was used to examine
differences in the mean speeds—for this we used the procedure for comparing population
means outlined by Kitchens (1987, p 369-373). The second test was used to explore
differences in the percentage of vehicles in the 10 mph pace and in the differences in the
proportions of vehicle traveling at various speeds. For this test, we treated the
distribution of speeds as a Bernoulli population—i.e., a population in which each element
is one of two possibilities, in this case, (1) in or out of the 10 mph pace, or (2) above or
below a selected speed (e.g., 75 mph). We then used the procedure for comparing
population proportions described by Kitchens (1987, pages 400-404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
ATR in the time periods under consideration. Second, the tests were conducted using an
extremely conservative correction, with n-values equal to the number of hours in each
test period—the rationale for this was that it is possible, when traffic is congested, that
individual vehicles may travel at speeds which are not independent of each other.
4.1. Speed Data Within Enhanced Enforcement Zones
There were four ATRs and one Tube located Within Enhanced Enforcement Zones on 4Lane Divided Highways. The locations of the ATRs were as follows; (1) ATR-172,on
US-10, near Dilworth, in Clay County, (2) ATR-187, on US-10, near Rice, in Benton
County, (3) ATR-188, on US-52, North of Rochester, in Olmstead County, and (4) ATR197, on SR-60, West of SR-4, in Watonwan County. The Tube—Tube 05—was located
on MN-60, near Lake Crystal, in Blue Earth County, and only collected speed data from
Westbound lanes. At the four ATR sites and the Tube site, the speed limit remained
unchanged at 65 mph.
A5-68
The effect of the MSMP on the speed data at each ATR and for the Tube is reported in
this section. For each ATR, two tables are presented for the Fourth Enhanced
Enforcement Period. Also for each ATR and the Tube, two tables are presented for the
Fourth Regular Enhancement Period. In the first of these tables, speed data from the Test
Year are compared with the available historical speed data. For the ATRs, if possible,
historical speed data from the three years prior to the MSMP are included in this table—
however sometimes data were only available from one or two of the prior years. Also in
some cases, speed data are not available from the whole of the Fourth Enhanced or the
Regular Enhancement Period—when this occurs, the dates from which the data are
available are noted in the table. For the Tube, seven days of historical Pre-MSMP data
were collected during August 2005. These data are compared with seven days of speed
data that were collected from the Tubes during the Fourth Regular Enforcement Period
(between July 17 and July 24). In the second of the tables for each ATR and for the
Tube, the focus is on drivers traveling at least 5 mph and at least 10 mph above the speed
limit (65 mph)—i.e., on drivers traveling at 70 mph or more and at 75 mph or more. In
the second table, we present the number (and proportion) of vehicles traveling above
these speeds. We also present the average number of vehicles traveling above these
speeds every day. Then, the table presents the decrease in the number of vehicles relative
to the number traveling at these speeds before the MSMP.
A5-69
ATR-172—Enhanced Enforcement Period #4
Table 4.1 (a): ATR-172—Comparison of Speed Data from the Fourth Enhanced
Enforcement Period with Speed Data from One Year Earlier
Measure
Test Period
(5/222/06 to 7/16/06)
Decrease/
Increase
Compared to
One Year Earlier
Mean (mph)
66.122830
-0.480822**
Percent in 10 mph pace
72.49030
+1.88026*
0.658750
-0.037089**
0.172129
-0.038792**
0.014096
-0.006072*
0.002465
-0.001284*
0.000756
-0.000316*
998,662
989,403
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.1 (b): ATR-172—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(5/22/06to 7/16/06)
5.31722*
66.63115
61.343527
70.700146
72.282090
73.864034
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-70
Table 4.2 (a): ATR-172—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Enhanced Enforcement Period #4 with Speed Data from One Year Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Test Period
(5/222/06 to 7/16/06)
Daily
Average in
Test Period
Decrease/
Increase
Compared to One
Year Earlier
171,899
3,070
-692
14,077
251
-108
998,662
17,833
—
Table 4.2 (b): ATR-172—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Enhanced Enforcement Period #4 with Speed Data from Speed Data from One Year
Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(5/222/06 to 7/16/06)
Daily
Average in
Test Period
Decrease/
Increase
Compared to One
Year Earlier
0.172129
0.172129
-0.038792
0.014096
0.014096
-0.006072
998,662
17,833
—
ATR-172—Regular Enforcement Period #4
Unfortunately, there were problems with the speed data collected at ATR-172 in the
Fourth Regular Enforcement Period—approximately half the data (361 hours out of 672)
were missing, and the remaining speed data were unreliable—and, as a result, we were
unable make meaningful comparisons with the historical speed data.
A5-71
ATR-187—Enhanced Enforcement Period #4
Table 4.3 (a): ATR-187—Comparison of Speed Data from the Fourth Enhanced
Enforcement Period with Speed Data from Two Earlier Years
Test Period
Decrease/
Increase Compared
to
Two Years Earlier
Decrease/
Increase Compared
to
Three Years Earlier
(Four Weeks Only
5/22/04 to 6/19/04)
(Four Weeks Only
5/22/03 to 6/19/03)
Measure
(32.125 Days Only
During
5/22/06 to 06/11/06
and
07/03/06 to 07/16/03)
Mean (mph)
67.393849
-1.549530**
-1.733564**
Percent in 10 mph
pace
61.40013
-7.94006**
-9.16616**
0.721882
-0.092732**
-0.103438**
0.350819
-0.081604**
-0.093059**
0.072229
-0.005350*
-0.008842**
0.012749
-0.001547*
-0.003420*
0.002356
0.000282*
-0.000718*
779,977
639,210
661,184
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.3 (b): ATR-187—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(32.125 Days Only During
5/22/06 to 06/11/06 and
07/03/06 to 07/16/03)
7.80100*
67.989816
61.952348
73.6042056
74.501581
76.868617
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-72
Table 4.4 (a): ATR-187—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Enhanced Enforcement Period #4 and Speed Data from Two and Three
Years Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Test Period
(32.125 Days
Only
During
5/22/06 to
06/11/06
and
07/03/06 to
07/16/03)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
273,631
8,518
-1,981
-2,259
56,337
1,754
-130
-215
—
—
Vehicle Total
779,977
24,279‫٭‬
‫[ ٭‬Please note—Average based on 31.125 days of data]
Table 4.4 (b): ATR-187—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Enhanced Enforcement Period #4 and Speed Data from Two and Three Years
Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Test Period
(32.125 Days
Only
During
5/22/06 to
06/11/06
and
07/03/06 to
07/16/03)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.350819
0.350819
-0.081604
-0.093059
0.072229
0.072229
-0.005350
-0.008842
—
—
Vehicle Total
779,977
24,279‫٭‬
‫[ ٭‬Please note—Average based on 31.125 days of data]
A5-73
ATR-187—Regular Enforcement Period #4
Table 4.5 (a): ATR-187—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Speed Data from Two Earlier Years
Decrease/Increase
Compared to
Three Years Earlier
Measure
(10.7 Days Only
During
7/17/06 to 7/30/06)
Decrease/Increase
Compared to
Two Years Earlier
(25.5 Days Only
During Four Week
Period)
Mean (mph)
66.923736
-2.735892**
-2.915186**
Percent in 10
mph pace
59.64958
-13.07925**
-13.60172**
0.733700
-0.119413**
-0.119744**
0.360396
-0.130316**
-0.140890**
0.073433
-0.034535*
-0.038871*
0.012908
-0.007370*
-0.012670*
0.002818
-0.001001*
-0.002631*
261,859
505,873
721,713
Test Period
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
(All Four Weeks)
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.5 (b): ATR-187—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(10.7 Days Only
During
7/17/06 to 7/30/06)
9.34097*
68.130160
61.827825
73.665905
74.537095
76.935785
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-74
Table 4.6 (a): ATR-187—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Regular Enforcement Period #4 and Speed Data from Two and Three Years
Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
94,373
8,820
-3,189
-3,448
19,229
1,797
-845
-951
261,859
24,473‫٭‬
—
—
Test Period
(10.7 Days
Only
During
7/17/06 to
7/30/06)
‫[ ٭‬Please note—Average based on 10.7 days of data]
Table 4.6 (b): ATR-187—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Regular Enforcement Period #4 and Speed Data from Two and Three Years Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.360396
0.360396
-0.130316
-0.140890
0.073433
0.073433
-0.034535
-0.038871
—
—
Test Period
(10.7 Days
Only
During
7/17/06 to
7/30/06)
Vehicle Total
261,859
24,473‫٭‬
‫[ ٭‬Please note—Average based on 10.7 days of data]
A5-75
ATR-188—Enhanced Enforcement Period #4
Table 4.7 (a): ATR-188—Comparison of Speed Data from the Fourth Enhanced
Enforcement Period with Speed Data from the Two Previous Years
Decrease/
Increase
Compared to
Two Years Earlier
(All Eight Weeks)
Measure
(Three Weeks Only
5/22/06 to 6/11/06)
Decrease/
Increase
Compared to
One Year Earlier
(All Eight Weeks)
Mean (mph)
61.166479
-6.055983**
-5.354665**
Percent in 10 mph pace
60.41119
+0.96134*
1.86939*
0.244234
-0.440572**
-0.385285**
0.083215
-0.243504**
-0.211652**
0.016675
-0.064270**
-0.049977**
0.002689
-0.006082*
-0.004583*
0.001334
-0.000380*
-0.000420*
659,806
1,764,460
1,700,876
Test Period
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.7 (b): ATR-188—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Three Weeks Only
5/22/06 to 6/11/06)
7.12269*
61.135388
55.528439
67.926182
69.478798
72.495866
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-76
Table 4.8 (a): ATR-188—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Enhanced Enforcement Period #4 and Speed Data from One and Two
Years Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to One
Year
Earlier
Decrease/
Increase
Compared
to Two
Years
Earlier
54,906
2,615
-7,651
-6,650
11,002
524
-2,019
-1,570
659,806
31,419
—
—
Test Period
(Three
Weeks Only
5/22/06 to
6/11/06)
Table 4.8 (b): ATR-188—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Enhanced Enforcement Period #4 and Speed Data from One and Two Years Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.083215
0.083215
-0.243504
-0.211652)
0.016675
0.016675
-0.064270
-0.049977
659,806
31,419
—
—
Test Period
(Three
Weeks Only
5/22/06 to
6/11/06)
While writing this report, Mn/DOT informed us that ATR-188 is located on a section of
US-52 which has been under construction since April 2006. For several months prior to
April 2006 there were occasional lane closures and some utility, surveying, and building
removal work being conducted along TH 52—these activities may all have affected
traffic speed. Also, this area was targeted very heavily by enforcement. This should be
considered when considering the large changes in speed noted at ATR-188.
A5-77
ATR-188—Regular Enforcement Period #4
No speed data were available for the Fourth Regular Enforcement Period—this is
because ATR-188 has been dismantled as part of the construction project on US-52
mentioned above.
A5-78
ATR-197—Enhanced Enforcement Period #4
Table 4.9 (a): ATR-197—Comparison of Speed Data from the Fourth Enhanced
Enforcement Period with Speed Data from Two Earlier Years
Measure
Test Period
(5/222/06 to
7/16/06)
Decrease/Increase
Compared to
Two Years Earlier
Decrease/Increase
Compared to
Three Years Earlier
Mean (mph)
65.938449
-0.363593**
+0.344654**
Percent in 10 mph
pace
66.42295
+3.28475*
+3.12284*
0.626127
-0.022691*
+0.036291*
0.209865
-0.039080**
-0.009717*
0.025558
-0.007750*
-0.007366*
0.005619
-0.001837*
-0.002187*
0.001259
-0.000595*
-0.000694*
286,017
284,770
319,643
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.9 (b): ATR-197—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(5/222/06 to 7/16/06)
6.13414*
66.514997
60.738623
71.624059
72.980489
74.336920
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-79
Table 4.10 (a): ATR-197—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Enhanced Enforcement Period #4 and Speed Data from Two and Three
Years Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(5/222/06 to
7/16/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
60,025
1,072
-200
-50
7,310
131
-40
-38
286,017
5,107
—
—
Table 4.10 (b): ATR-197—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Enhanced Enforcement Period #4 and Speed Data from Two and Three Years
Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(5/222/06 to
7/16/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.209865
0.209865
-0.039080
-0.009717
0.025558
0.025558
-0.007750
-0.007366
286,017
5,107
—
—
A5-80
ATR-197—Regular Enforcement Period #4
Table 4.11 (a): ATR-197—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Speed Data from Two Earlier Years
Measure
Test Period
(7/17/06 to
8/13/06)
Decrease/Increase
Compared to
Two Years Earlier
Decrease/Increase
Compared to
Three Years Earlier
Mean (mph)
66.305439
-0.294511**
+0.427805**
Percent in 10 mph
pace
65.03346
+1.65031*
+3.79475*
0.648985
-0.028547*
+0.032290*
0.234673
-0.030494*
-0.010127*
0.034047
-0.003347*
-0.005451*
0.007199
-0.001316*
-0.002334*
0.001394
-0.000776*
-0.000933*
147,797
151,150
146,969
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.11 (b): ATR-197—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to
8/13/06)
6.12270*
66.797980
60.955917
72.110220
73.356317
74.602413
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-81
Table 4.12 (a): ATR-197—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Regular Enforcement Period #4 and Speed Data from Two and Three Years
Earlier
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(7/17/06 to
8/13/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
34,684
1,239
-161
-53
5,032
180
-18
-29
147,797
5,278
—
—
Table 4.12 (b): ATR-197—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Regular Enforcement Period #4 and Speed Data from Two and Three Years Earlier
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(7/17/06 to
8/13/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
0.234673
0.234673
-0.030494
-0.010127
0.034047
0.034047
-0.003347
-0.005451
147,797
5,278
—
—
A5-82
Tube 05—Regular Enforcement Period #4
Table 4.13 (a): Tube 05—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Pre-MSMP Speed Data from August 2005
Measure
Test Period
(7/18/06 to 7/24/06)
(Westbound Lanes Only)
Decrease/Increase
Compared to Pre-Test
Period
(8/22 to 8/29/06)
(Eastbound Lanes Only)
Mean (mph)
68.549153
-8.325943**
Percent in 10 mph pace
71.83367
+5.43173*
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
0.814700
0.337696
0.056455
0.023144
0.0157498
-0.158236**
-0.578921**
-0.612667**
-0.201202**
-0.036437*
Vehicle Total
27,048
32,441
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.13 (b): Tube 05—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/18/06 to
7/24/06)
(Westbound
Lanes Only)
5.51795*
68.298713
63.771803
73.336927
74.225845
75.968923
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-83
Table 4.14 (a): Tube 05—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Regular Enforcement Period #4 with Speed Data from the Pre-MSMP
Period (in August 2005)
Measure
Number of vehicles at
70 mph or more
Number of vehicles at
75 mph or more
Vehicle Total
Test Period
(7/18/06 to 7/24/06)
(Westbound Lanes
Only)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(8/22 to 8/29/06)
(Eastbound Lanes
Only)
9,134
1,305
-2,236
1,527
218
-2,367
27,048
3,864
—
Table 4.14 (b): Tube 05—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Regular Enforcement Period #4 with Speed Data from Speed Data from the PreMSMP Period (in August 2005)
Measure
Proportion of vehicles
at 70 mph or more
Proportion of vehicles
at 75 mph or more
Vehicle Total
Test Period
(7/18/06 to 7/24/06)
(Westbound Lanes
Only)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(8/22 to 8/29/06)
(Eastbound Lanes
Only)
0.337696
0.337696
-0.578921
0.056455
0.056455
-0.612667
27,048
3,864
—
The massive differences in the numbers of vehicles traveling at least 5 mph above and at
least 10 mph above the speed limit—i.e., at 70 mph or more and at 75 mph or more,
respectively—suggest that, in addition to enhanced enforcement, it is highly likely that
other factors contributed to the differences. It is possible that one such factor is that Tube
05 was installed on the Eastbound lanes in August 2005 and the Westbound lanes in July
2006. However, revisiting the historical speed data suggests that it may have been
erroneous—for instance, it seems extremely unlikely that the proportion of vehicles
traveling at 75 mph or more on MN-60, near Lake Crystal, was as high as 0.669 (21,707
out of 32,441). Because of our doubts about the validity of the comparisons for Tube 05,
A5-84
we have omitted the Tube 05 data from the summary tables at the end of this section of
the report.
4.2. Speed Data from One ATR located Outside Enhanced Enforcement Zones
There was one ATR located on a 4-Lane Divide Highway Outside the Enhanced
Enforcement Zones. It was ATR-353, on MNTH-169 near Jordan in Scott County.
There were no changes in enforcement at this location. For this ATR, the speed data
obtained during 2005, when the MSMP occurred, was compared with historical speed
data. Comparisons are presented for the eight-week time period between 2/27/06 and
4/23/06, when the Fourth Enhanced Enforcement Period occurred during the MSMP, and
then for the four-week time period between 4/24/06, when the Fourth Regular
Enhancement Period occurred.
Two tables are presented for each of these time periods. In the first table, speed data
from the Test Year are compared with historical speed data. Speed data was only
available for the two years prior to the MSMP for ATR-353. In the second table, the
focus is on drivers who were traveling at least 5 mph and at least 10 mph above the speed
limit—i.e., drivers traveling at 70 mph or more and at 75 mph or more. In this second
table, we present the number (and proportion) of vehicles traveling above these speeds
throughout the six-week Enhanced Enforcement Period or the four-week Regular
Enhancement Period. We also present the average number of vehicles traveling above
these speeds every day. Then, the table presents the decrease in the number of vehicles
relative to the number that were traveling at these speeds in the two years prior to the
implementation of the MSMP.
A5-85
ATR-353—Enhanced Enforcement Period #4
Table 4.15 (a): ATR-353—Comparison of Speed Data from the Fourth Enhanced
Enforcement Period with Speed Data from Three Previous Years
Decrease/Increase
Compared to
Two Years
Earlier
Measure
Test Period
(5/222/06 to
7/16/06)
Decrease/Increase
Compared to
One Year Earlier
Decrease/Increase
Compared to
Two Years
Earlier
Mean (mph)
67.554869
-0.583262**
-0.469247**
-0.499568**
Percent in 10
mph pace
67.51270
-0.36289*
-0.71747*
-0.13464*
0.755923
-0.033967**
-0.028462*
-0.030176*
0.326071
-0.059468**
-0.040699**
-0.051423**
0.029695
-0.016206**
-0.010947*
-0.015845**
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
0.003415
-0.002590*
-0.001851*
-0.002661*
0.0005103
-0.000427*
-0.000329*
-0.000436*
Vehicle Total
1,293,359
1,293,813
1,100,110
1,250,662
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.15 (b): ATR-353—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(5/222/06 to 7/16/06)
5.88916*
67.976869
62.548543
72.970392
73.813917
74.657441
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-86
Table 4.16 (a): ATR-353—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Enhanced Enforcement Period #4 and During the Previous Three Years
Measure
Number of vehicles
at 70 mph or more
Number of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Increase
Test Period
(5/22/06to
7/16/06)
Daily
Average
in Test
Period
Compared
to One
Year
Earlier
Compared
to Two
Years
Earlier
Compared
to Three
Years
Earlier
421,726
7,531
-1,373
-940
-1,188
38,406
686
-374
-253
-366
1,293,359
23,095
—
—
Decrease/
Table 4.16 (b): ATR-353—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Enhanced Enforcement Period #4 and During the Previous Three Years
Measure
Proportion of
vehicles at 70 mph
or more
Proportion of
vehicles at 75 mph
or more
Vehicle Total
Decrease/
Decrease/
Decrease/
Increase
Increase
Increase
Test Period
(5/22/06to
7/16/06)
Daily
Average
in Test
Period
Compared
to One
Year
Earlier
Compared
to Two
Years
Earlier
Compared
to Three
Years
Earlier
0.326071
0.326071
-0.059468
-0.040699
-0.051423
0.029695
0.029695
-0.016206
-0.010947
-0.015845
1,293,359
23,095
—
—
A5-87
ATR-353—Regular Enforcement Period #4
Table 4.17 (a): ATR-353—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Speed Data from the Three Previous Years
Decrease/Increase
Compared to
Three Years
Earlier
Measure
Test Period
(7/17/06 to
8/13/06)
Decrease/Increase
Compared to
One Year Earlier
Decrease/Increase
Compared to
Two Years
Earlier
Mean (mph)
67.465322
-0.792071**
-0.645079**
-0.74995**
Percent in 10
mph pace
67.18965
-0.99044*
-0.81761*
-0.56350*
0.754748
-0.044390*
-0.037853*
-0.041192*
0.325656
-0.073502**
-0.060417**
-0.071551**
0.029709
-0.020970*
-0.015809*
-0.022469**
0.003397
-0.003408*
-0.002457*
-0.003844*
0.000520
-0.000521*
-0.000411*
-0.000568*
655,603
682,852
678,857
651,812
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 4.17 (b): ATR-353—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to
8/13/06)
6.23986*
67.968453
62.507999
72.967688
73.812433
74.657178
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-88
Table 4.18 (a): ATR-353—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph)
During Regular Enforcement Period #4 and During the Previous Three Years
Decrease/
Measure
Number of vehicles
at 70 mph or more
Number of vehicles
at 75 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Increase
Test Period
(7/17/06 to
8/13/06)
Daily
Average
in Test
Period
Compared
to One
Year
Earlier
Compared
to Two
Years
Earlier
Compared
to Three
Years
Earlier
213,501
7,625
-1,721
-1,415
-1,675
19,477
696
-491
-370
-526
655,603
23,414
—
—
—
Table 4.18 (b): ATR-353—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 65 mph) During
Regular Enforcement Period #4 and During the Previous Three Years
Measure
Proportion of
vehicles at 70 mph
or more
Proportion of
vehicles at 75 mph
or more
Vehicle Total
Decrease/
Decrease/
Decrease/
Increase
Increase
Increase
Test Period
(7/17/06 to
8/13/06)
Daily
Average
in Test
Period
Compared
to One
Year
Earlier
Compared
to Two
Years
Earlier
Compared
to Three
Years
Earlier
0.325656
0.325656
-0.073502
-0.060417
-0.071551
0.029709
0.029709
-0.020970
-0.015809
-0.022469
655,603
23,414
—
—
—
4.3. Overall Effect of MSMP on 4-Lane Divided Highways
In the MSMP, we obtained speed data from five ATRs and one Tube located on 4-Lane
Divided Highways. As mentioned above, the comparisons for the Tube are questionable
and, because of that, are not included in the summary tables that follow. With regard to
the ATRs, four were located Within Enhanced Enforcement Zones, while the remaining
ATR was located Outside the Enhanced Enforcement Zones. At the locations of the four
ATRs Within the Enhanced Enforcement Zones and the ATR Outside the Enhanced
Enforcement Zones, the speed limit was unchanged—at 65mph—during the MSMP.
A5-89
In order to provide a brief overall summary of the effect of the MSMP, speed data from
the four ATRs Within Enhanced Enforcement Zones were combined. For this summary,
again we focused on drivers traveling at least 10 mph above the speed limit—i.e., on
drivers traveling at 75 mph or more. Then, we compared speed data from the Test Year
with data from previous years—in the case of ATR-172 and ATR-188 the data are from
one year earlier, while for ATR-187 and ATR-197 the data are from two years earlier.
Table 4.19 shows the results of this comparison for the Fourth Enhanced Enforcement
Period.
Table 4.19: Effect of the MSMP at Four ATRs Within Enhanced Enforcement
Zones on 4-Lane Divided Highways during the Fourth Enhanced Enforcement
Period
Sample Total
4,317,053*
Sample Total
4,403,811**
Pre-MSMP
# Over 75 mph
271,441*
Fourth Enhanced Enforcement Period
# Over 75 mph
148,932**
% Over 75 mph
6.29*
% Over 75 mph
3.38**
Result: 46.27% Reduction in Drivers Traveling Over 75 mph
*Numbers adjusted to account for limited availability of data from ATR-187 (4 weeks—as opposed to eight
weeks for ATR-172, ATR-188, and ATR-197). Also, data for ATR-172 and ATR-188 are from one year
earlier, while data for ATR-187 and ATR-197 are from two years earlier.
**Numbers adjusted to account for limited availability of data from ATR-187 (32.125 days) and ATR-188
(21 days), as opposed to 56 days (all eight weeks) for ATR-172 and ATR-197.
Table 4.19 indicates that, for four ATRs located Within Enhanced Enforcement Zones on
4-Way Divided Highways, during the Fourth Enhanced Enforcement Period, there was a
46.27% decrease in the number of drivers traveling over 75 mph—i.e., 10 mph over the
speed limit. It should also be noted that speed data from ATR-188 heavily influenced the
resultant reduction. This is because, as noted earlier, ATR-188 was located on a section
of US-52 that has been under construction since April 2006. For several months prior to
April 2006, there were occasional lane closures and some utility, surveying, and building
removal work being conducted along TH 52—these activities may all have affected
traffic speed. Also, this area was targeted very heavily by enforcement. [If the data from
ATR-188 are eliminated from the comparison, then the resultant reduction was 10.12%
for the remaining three ATRs.]
A similar comparison was conducted for the Fourth Regular Enforcement Period. For
this time period, the speed data were available for ATR-187 and ATR-197 (in both case
the comparison data were from two years earlier) and Tube 05 (for which the comparison
data were from August 2005). The results of this comparison are shown in Table 4.20.
A5-90
Table 4.20: Effect of the MSMP at Two ATRs (ATR-187 and ATR-197) and one
Tube Within Enhanced Enforcement Zones on 4-Lane Divided Highways during the
Fourth Regular Enforcement Period
Sample Total
706,618*
Sample Total
833,036**
Pre-MSMP
# Over 75 mph
65,625*
Fourth Regular Enforcement Period
# Over 75 mph
55,351**
% Over 75 mph
9.29*
% Over 75 mph
6.64**
Result: 28.53 % Reduction in Drivers Traveling Over 75 mph
*Numbers adjusted to account for limited availability of data from ATR-187 (25.5 days—as opposed to 28
days for ATR-197. Also, the data for ATR-187 and ATR-197 are from two years earlier.
**Numbers adjusted to account for limited availability of data from ATR-187 (10.7 days—as opposed to
28 days from ATR-197.
Table 4.20 shows that, for two ATRs Within Enhanced Enforcement Zones on 4-Way
Divided Highways, during the Fourth Regular Enforcement Period there was a 28.53%
reduction in the number of drivers traveling over 75 mph—i.e., 10 mph or more above
the speed limit.
We also examined the difference between the speed data obtained, during the Test
Periods and before the MSMP began, from the single ATR Outside the Enhanced
Enforcement Zones. For comparison purposes, we again focused on drivers traveling at
75 mph or more—10 mph above the speed limit. The results of this comparison for
speed data obtained during the Fourth Enhanced Enforcement Period are shown in Table
4.21.
Table 2.21: Effect of the MSMP at One ATR Outside the Enhanced Enforcement
Zones on a 4-Way Divided Highway During the Fourth Enhanced Enforcement
Period
Sample Total
1,293,813
Sample Total
1,293,359
One Year Before MSMP
# Over 75 mph
59,387
Fourth Enhanced Enforcement Period
# Over 75 mph
38,406
% Over 75 mph
4.59
% Over 75 mph
2.97
Result: 35.29% Reduction in Drivers Traveling Over 75 mph
Table 4.21 shows that, for the single ATR located Outside the Enhanced Enforcement
Zones on a 4-Way Divided Highway, during the Fourth Enhanced Enforcement Period,
there was a 35.29% decrease in the number of drivers traveling over 75 mph—i.e., 10
mph or more above the speed limit.
A5-91
A similar comparison was conducted for the Fourth Regular Enforcement Period. The
results of this comparison are shown in Table 4.22.
Table 4.22: Effect of the MSMP at One ATR Outside the Enhanced Enforcement
Zones on a 4-Way Divided Highway During the Fourth Regular Enforcement Period
Sample Total
682,852
Sample Total
655,603
One Year Before MSMP
# Over 75 mph
34,606
Fourth Regular Enforcement Period
# Over 75 mph
19,477
% Over 75 mph
5.07
% Over 75 mph
2.97
Result: 41.42% Reduction in Drivers Traveling over 75 mph
Table 4.22 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
a 4-Way Divided Highway, during the Fourth Regular Enforcement Period there was a
41.42% decrease in the number of drivers traveling over 75 mph—i.e., at 10 mph over
the speed limit.
Comparisons between speed data from the ATRs and Tube located Within Enhanced
Enforcement Zones and the ATR located Outside the Enhanced Enforcement Zones
should be treated with caution. The ATRs and Tube located Within Enhanced
Enforcement Zones were scattered throughout Minnesota; in contrast, the single ATR
Outside the Enhanced Enforcement Zones is located a few miles to the South-West of the
Twin Cities—and a great number of the drivers traveling past this ATR may have
traveled through Enhanced Enforcement Zones in the Cities.
A5-92
Section 5. Speed Data Obtained on Rural Freeways
In the Fourth MSMP Period, we obtained speed data from five ATRs and two Tubes that
were located on Rural Freeways. Unfortunately, the speed data for one of the Tubes
(Tube 07) were collected from passing lanes only—they had been collected from all
lanes in the Pre-MSMP time period and, as a result, the comparison between the PreMSMP time period and Fourth MSMP Period was compromised.
Four of the ATRs and the Tube for which we had comparable data were located Within
Enhanced Enforcement Zones, while the fifth ATR was located Outside the Enhanced
Enforcement Zones. At all the ATR and Tube locations, the speed limit was
unchanged—at 70 mph—during the MSMP.
In this section of the report, for the ATRs and Tube 06 (for which the speed data were
comparable), which were located Within Enhanced Enforcement Zones and for the ATR
located Outside the Enhanced Enforcement Zones, we present comparisons of the speed
data obtained during the Test Year with speed data obtained prior to the MSMP.
Comparisons using the speed data from Within Enhanced Enforcement Zones are
presented first. Then, we present comparisons using the speed data from the ATR located
Outside the Enhanced Enforcement Zones.
In making the comparisons between the speed data obtained during the Test Year and the
speed data obtained prior to the MSMP, we used two statistical tests. The first test was
used to examine differences in the mean speeds—for this we used the procedure for
comparing population means outlined by Kitchens (1987, p 369-373). The second test
was used to explore differences in the percentage of vehicles in the 10 mph pace and in
the differences in the proportions of vehicle traveling at various speeds. For this test, we
treated the distribution of speeds as a Bernoulli population—i.e., a population in which
each element is one of two possibilities, in this case, (1) in or out of the 10 mph pace, or
(2) above or below a selected speed (e.g., 75 mph). We then used the procedure for
comparing population proportions described by Kitchens (1987, pages 400-404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
ATR or Tube 06 in the time periods under consideration. Second, the tests were
conducted using an extremely conservative correction, using n-values equal to the
number of hours in each test period—the rationale for this was that it is possible, when
traffic is congested, that individual vehicles may travel at speeds which are not
independent of each other.
5.1. Speed Data Within Enhanced Enforcement Zones
The four ATRs located Within Enhanced Enforcement Zones on Rural Freeways were as
follows: (1) ATR-175, on I-94, near Saulk Centre in Stearns County, (2) ATR-191, on I-
A5-93
35, near Wyoming, in Chisago County, (3) ATR-208, on I-35, near Owatanna in Steele
County, and (4) ATR-227, on I-90, near Alden in Freeborn County. Tube 06 was located
on I-94, near Fergus Falls in Otter Tail County. During the MSMP, there was no change
in the speed limit—it remained at 70 mph—at the locations of the four ATRs or Tube 06.
Seven days of speed data were collected with Tube 06 during the Fourth Regular
Enforcement Period: These data were collected—from the Eastbound lanes only—
between July 17 and July 24. These data were compared with seven days of historical
Pre-MSMP data collected from Tube 06—also from the Eastbound lanes—during August
2005.
For each of the four ATRs Within Enhanced Enforcement Zones, two tables are presented
for each time period, and for Tube 06 for the Fourth Regular Enforcement Period. In the
first of these tables, speed data from the Test Year are compared with the available
historical speed data. Where possible for the ATRs, speed data from the three years prior
to the MSMP are included in the first table—however, in some cases, data are only
available from one or two of the prior years. Also in some cases, speed data are not
available from the whole of the Fourth Enhanced or Regular Enhancement Periods—in
these cases the dates from which the data are available are noted in the table. In the
second of the tables, the focus is on drivers traveling at least 5 mph and at least 10 mph
above the speed limit—i.e., on drivers traveling at 75 mph or more and at 80 mph or
more. In this second table, we present the number (and proportion) of vehicles traveling
above these speeds throughout the time periods. We also present the average number of
vehicles traveling above these speeds each day. Then, the table presents the decrease in
the number of vehicles relative to the number that were traveling at these speeds before
the MSMP.
A5-94
ATR-175—Enhanced Enforcement Period #4
Table 5.1 (a): ATR-175—Comparison of Speed Data from the Fourth Enhanced
Enforcement Period with Speed Data from the Three Previous Years
Decrease/Increase Decrease/Increase
Compared To
Compared To
Two Years
One Year Earlier
Earlier
(All Eight Weeks) (All Eight Weeks)
Decrease/Increase
Compared To
Three Years Earlier
Measure
Test Period
(Four Weeks
Only
06/19/06 to
07/16/06)
Mean (mph)
71.800427
-1.378501**
-1.447568**
+0.767893**
Percent in 10
mph pace
67.426018
+3.55766*
+3.23565*
+15.58817**
0.907996
-0.009902*
-0.013030*
+0.097109**
0.715044
-0.063604**
-0.064093**
+0.133882**
0.237864
-0.143411**
-0.145973**
-0.049548**
0.033448
-0.048050**
-0.047301**
-0.048922**
0.003921
-0.006360*
-0.006556*
-0.015402**
710,870
1,429,654
1,388,157
1,409,263
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
(Four Weeks Only)
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.1 (b): ATR-175—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Four Weeks Only
06/19/06 to 07/16/06)
5.71596*
72.253275
66.502854
77.149137
78.372135
79.595133
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-95
Table 5.2 (a): ATR-175—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Enhanced Enforcement Period #4 and During the Previous Three Years
Measure
Number of vehicles
at 75 mph or more
Number of vehicles
at 80 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Increase
Daily
Average
in Test
Period
Compared
to One
Year
Earlier
Compared
to Two
Years
Earlier
Compared
to Three
Years
Earlier
169,090
6,039
-3,641
-3,706
-1,258
23,777
849
-1,220
-1,201
-1,242
710,870
25,388
—
—
—
Test Period
(Four Weeks
Only
06/19/06 to
07/16/06)
Decrease/
Table 5.2 (b): ATR-175—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Enhanced Enforcement Period #4 and During the Previous Three Years
Measure
Proportion of
vehicles at 75 mph
or more
Proportion of
vehicles at 80 mph
or more
Vehicle Total
Decrease/
Decrease/
Decrease/
Increase
Increase
Increase
Daily
Average
in Test
Period
Compared
to One
Year
Earlier
Compared
to Two
Years
Earlier
Compared
to Three
Years
Earlier
0.237864
0.237864
-0.143411
-0.145973
-0.049548
0.033448
0.033448
-0.048050
-0.047301
-0.048922
710,870
25,388
—
—
—
Test Period
(Four Weeks
Only
06/19/06 to
07/16/06)
A5-96
ATR-175—Regular Enforcement Period #4
Table 5.3 (a): ATR-175—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Speed Data from Two Prior Years
Decrease/Increase Decrease/Increase
Compared to
Compared to
Three Years
Two Years
Earlier
Earlier
Measure
Test Period
(7/17/06 to
8/13/06)
Mean (mph)
71.968357
-1.713950**
+0.458237**
Percent in 10
mph pace
66.0344
+0.08193*
+16.15583**
0.906255
-0.022071*
+0.089069**
0.717949
-0.082309**
+0.120977**
0.257345
-0.161111**
-0.058720**
0.039995
-0.057198**
-0.063588**
0.004836
-0.007943*
-0.022738**
720,413
747,855
750,013
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.3 (b): ATR-175—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to
8/13/06)
5.70065*
72.365908
66.493718
77.469411
78.619627
79.769844
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-97
Table 5.4 (a): ATR-175—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Regular Enforcement Period #4 and Speed Data from Two and Three Years
Earlier
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(7/17/06 to
8/13/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
185,395
6,621
-4,145
-1,511
28,813
1,029
-1,472
-1,636
720,413
25,729
—
—
Table 5.4 (b): ATR-175—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Regular Enforcement Period #4 and Speed Data from Two and Three Years Earlier
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(7/17/06 to
8/13/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
0.257345
0.257345
-0.161111
-0.058720
0.039995
0.039995
-0.057198
-0.063588
720,413
25,729
—
—
ATR-191: Enhanced Enforcement Period #4
Throughout the Fourth Enhanced Enforcement Period, there were problems with the
speed data collected at ATR-191. However, these problems were with the data collection
in one of the Southbound lanes—and, by using speed data only from the Northbound
lanes, we were able to make the comparisons with historical speed data that appear in
Table 5.5 and Table 5.6.
A5-98
Table 5.5 (a): ATR-191—Comparison of Speed Data from the Fourth Enhanced
Enforcement Period with Speed Data from the Two Prior Years
Decrease/Increase Decrease/Increase
Compared to
Compared to
Three Years Earlier
Two Years
(All Lanes)
Earlier
(Four Weeks Only)
(All Lanes)
Measure
Test Period
(5/22/06 to
7/16/06)
(Northbound
Lanes Only)
Mean (mph)
68.297599
-4.829806**
-2.628736**
Percent in 10
mph pace
42.44396
-16.63083**
-1.87158*
0.685137
-0.226709**
-0.093321**
0.474357
-0.277273**
-0.110426**
0.238889
-0.184715**
-0.095813**
0.063083
-0.036422**
-0.081185**
0.013747
-0.000308*
-0.016734**
1,450,541
2,722,002
2,720,508
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.5 (b): ATR-191—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(5/22/06 to 7/16/06)
(Northbound Lanes Only)
10.33294*
69.391722
60.191158
77.528045
78.950071
81.325924
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-99
Table 5.6 (a): ATR-191—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Enhanced Enforcement Period #4 and Speed Data from Two and Three
Years Earlier
(Northbound
Lanes Only)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
346,518
6,188
-4,785
-2,419
91,505
1,634
-943
-2,103
1,450,541
25,903
—
—
Test Period
(5/22/06 to
7/16/06)
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Table 5.6 (b): ATR-191—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Enhanced Enforcement Period #4 and Speed Data from Two and Three Years
Earlier
(Northbound
Lanes Only)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.238889
0.238889
-0.184715
-0.095813
0.063083
0.063083
-0.036422
-0.081185
Test Period
(5/22/06 to
7/16/06)
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
ATR-191—Regular Enforcement Period #4
There were also problems with the speed data collected at ATR-191 throughout the
Fourth Regular Enforcement Period. As in the Enhanced Enforcement Period, the data
collection problems were with one of the Southbound lanes. Again, by using speed data
from the Northbound lanes, we were able to make the comparisons with the historical
speed data that appear in Table 5.7 and Table 5.8.
A5-100
Table 5.7 (a): ATR-191—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Speed Data from the Two Prior Years
Decrease/Increase
Compared to
One Year Earlier
Measure
Test Period
(7/17/06 to
8/13/06)
(Northbound
Lanes Only)
(All Lanes)
Decrease/Increase
Compared to
Three Years
Earlier
(All Lanes)
Mean (mph)
71.408375
-1.186311**
-0.166741**
Percent in 10
mph pace
58.85982
+1.72143*
+14.63901**
0.897114
-0.013556*
+0.101335**
0.671169
-0.050921**
+0.074114**
0.313835
-0.078018**
-0.036397*
0.069005
-0.032970**
-0.093102**
0.008176
-0.005305*
-0.025703**
854,341
1,588,824
1,472,176
Proportion at
65 mph or
more
Proportion at
70 mph or
more
Proportion at
75 mph or
more
Proportion at
80 mph or
more
Proportion at
85 mph or
more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.7 (b): ATR-191—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to 8/13/06)
(Northbound Lanes
Only)
8.44434*
72.395082
66.042593
78.345900
79.367014
81.562176
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-101
Table 5.8 (a): ATR-191—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Regular Enforcement Period #4 and Speed Data from Two and Three Years
Earlier
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
268,122
9,576
-2,380
-1,111
58,954
2,106
-1,006
-2,841
854,341
30,512
—
—
Test Period
(7/17/06 to
8/13/06)
(Northbound
Lanes Only)
Table 5.8 (b): ATR-191—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Regular Enforcement Period #4 and Speed Data from Two and Three Years Earlier
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.313835
0.313835
-0.078018
-0.036397
0.069005
0.069005
-0.032970
-0.093102
854,341
30,512
—
—
Test Period
(7/17/06 to
8/13/06)
(Northbound
Lanes Only)
ATR-208: Enhanced Enforcement Period #4 and Regular Enforcement Period #4
There were also problems with the speed data collected at ATR-208, throughout the
Fourth Enhanced Enforcement Period and Fourth Regular Enforcement Period. Because
these data were unreliable, we were could not make reliable comparisons with the
historical speed data.
A5-102
ATR-227: Enhanced Enforcement Period #4
Table 5.9 (a): ATR-227—Comparison of Speed Data from the Fourth Enhanced
Enforcement Period with Speed Data from the Previous Two Years
Decrease/Increase
Compared to
One Year Earlier
(Four Weeks
Only)
Decrease/Increase
Compared to
Two Years Earlier
Measure
Test Period
(Four Weeks
Only
5/22/06 to
6/18/06)
(All Eight Weeks)
Decrease/Increase
Compared to
Three Years
Earlier
(All Eight Weeks)
Mean (mph)
71.330830
-0.788008**
-0.741198**
+4.538993**
Percent in 10
mph pace
65.46696
+2.06244*
+4.72527**
+16.34785**
0.887359
-0.016770*
0.001655*
+0.215375**
0.673520
-0.040761*
-0.027725*
+0.312688**
0.229821
-0.068466**
-0.083742*
+0.112292**
0.026760
-0.015126*
-0.017220*
+0.001025*
0.004368
-0.002484*
-0.002845*
-0.000343*
304,481
339,613
631,893
657,398
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.9 (b): ATR-227—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Four Weeks Only
5/22/06 to 6/18/06)
6.08957*
71.955377
65.873533
76.965440
78.196602
79.427763
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-103
Table 5.10 (a): ATR-227—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Enhanced Enforcement Period #4 and During the Previous Three Years
Measure
Number of vehicles
at 75 mph or more
Number of vehicles
at 80 mph or more
Vehicle Total
Decrease/
Decrease/
Decrease/
Increase
Increase
Increase
Daily
Average
in Test
Period
Compared
to One
Year
Earlier
Compared
to Two
Years
Earlier
Compared
to Three
Years
Earlier
69,976
2,499
-745
-911
+1,221
8,148
291
-164
-187
+11
304,481
10,874
—
—
—
Test Period
(Four Weeks
Only
5/22/06 to
6/18/06)
Table 5.10 (b): ATR-227—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Enhanced Enforcement Period #4 and During the Previous Three Years
Decrease/
Measure
Proportion of
vehicles at 75 mph
or more
Proportion of
vehicles at 80 mph
or more
Vehicle Total
Decrease/
Decrease/
Test Period
(Four Weeks
Only
5/22/06 to
6/18/06)
Increase
Increase
Increase
Daily
Average
in Test
Period
Compared
to One
Year
Earlier
Compared
to Two
Years
Earlier
Compared
to Three
Years
Earlier
0.229821
0.229821
-0.068466
-0.083742
+0.112292
0.026760
0.026760
-0.015126
-0.017220
+0.001025
304,481
10,874
—
—
—
A5-104
ATR-227—Regular Enforcement Period #4
Table 5.11 (a): ATR-227—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Speed Data from the Previous Two Years
Decrease/Increase Decrease/Increase Decrease/Increase
Compared to
Compared to
Compared to
Three Years
Two Years
One Year Earlier
Earlier
Earlier
(All Four Weeks) (All Four Weeks) (All Four Weeks)
Measure
Test Period
(One Week Only
7/24/06 to
7/30/06)
Mean (mph)
71.275318
-0.808872**
-1.007352**
+6.331979**
Percent in 10
mph pace
64.25295
+1.88150*
+3.59506*
+20.81393**
0.878537
-0.019283*
-0.011560*
+0.207691**
0.665469
-0.043867*
-0.047833*
+0.293702**
0.234403
-0.068438*
-0.096972**
+0.116484**
0.027625
-0.017796*
-0.022129*
+0.003419*
0.004080
-0.003697*
-0.003791*
-0.000550*
82,354
363,495
355495
380,153
Proportion at
65 mph or
more
Proportion at
70 mph or
more
Proportion at
75 mph or
more
Proportion at
80 mph or
more
Proportion at
85 mph or
more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.11 (b): ATR-227—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(One Week Only
7/24/06 to 7/30/06)
6.04550*
71.919296
65.669659
77.040901
78.249927
79.458952
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-105
Table 5.12 (a): ATR-227—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Regular Enforcement Period #4 and During the Previous Three Years
Measure
Number of vehicles
at 75 mph or more
Number of vehicles
at 80 mph or more
Vehicle Total
Decrease/
Decrease/
Increase
Increase
Increase
Daily
Average
in Test
Period
Compared
to One
Year
Earlier
Compared
to Two
Years
Earlier
Compared
to Three
Years
Earlier
19,304
2,758
-803
-1,141
+1,370
2,275
325
-209
-260
+40
82,354
11,765
—
—
—
Test Period
(One Week
Only
7/24/06 to
7/30/06)
Decrease/
Table 5.12 (b): ATR-227—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Regular Enforcement Period #4 and During the Previous Three Years
Measure
Proportion of
vehicles at 75 mph
or more
Proportion of
vehicles at 80 mph
or more
Vehicle Total
Decrease/
Decrease/
Decrease/
Increase
Increase
Increase
Daily
Average
in Test
Period
Compared
to One
Year
Earlier
Compared
to Two
Years
Earlier
Compared
to Three
Years
Earlier
0.234403
0.234403
-0.068438
-0.096972
+0.116484
0.027625
0.027625
-0.017796
-0.022129
+0.003419
82,354
11,765
—
—
—
Test Period
(One Week
Only
7/24/06 to
7/30/06)
A5-106
Tube 06—Regular Enforcement Period #4
Table 5.13 (a): Tube 06—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Pre-MSMP Speed Data from August 2005
Measure
Test Period
(7/17/06 to 7/24/06)
(Eastbound Lanes Only)
Decrease/Increase
Compared to Pre-Test
Period
(8/11/05 to 8/27/05)
(Eastbound Lanes Only)
Mean (mph)
68.933534
+0.748866**
Percent in 10 mph pace
62.43821
ns (-0.3263)
Proportion at 65 mph or more
Proportion at 70 mph or more
Proportion at 75 mph or more
Proportion at 80 mph or more
Proportion at 85 mph or more
0.777087
0.473409
0.108427
0.009168
0.003029
+0.02594*
+0.069897*
+0.043708*
+0.002078*
ns
Vehicle Total
63,047
62,764
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.13 (b): Tube 06—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to 7/24/06)
(Eastbound Lanes
Only)
5.83499*
69.562180
62.683694
74.430479
75.424497
77.943153
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-107
Table 5.14 (a): Tube 06—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Regular Enforcement Period #4 with Speed Data from the Pre-MSMP
Period (in August 2005)
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Test Period
(7/17/06 to 7/24/06)
(Eastbound Lanes
Only)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(8/11/05 to 8/27/05)
(Eastbound Lanes
Only)
6,836
977
+394
578
83
+19
63,047
9,007
—
Table 5.14 (b): Tube 06—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Regular Enforcement Period #4 with Speed Data from Speed Data from the PreMSMP Period (in August 2005)
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Test Period
(7/17/06 to 7/24/06)
(Eastbound Lanes
Only)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(8/11/05 to 8/27/05)
(Eastbound Lanes
Only)
0.108427
0.108427
+0.043708
0.009168
0.009168
+0.002078
63,047
9,007
—
A5-108
5.2. Speed Data from One ATR located Outside Enhanced Enforcement Zones
There was one ATR located on a Rural Freeway Outside the Enhanced Enforcement
Zones. It was ATR-200, on I-94, near Hasty in Wright County. During the MSMP, at
this ATR location the speed limit remained unchanged at 70 mph, and there was no
change in enforcement.
Two tables are presented for both the Fourth Enhanced Enforcement Period and the
Fourth Regular Enforcement Period. In the first of these table, speed data from the Test
Year are compared with the historical speed data. In the second table, the focus is on
drivers who were traveling at least 5 mph and at least 10 mph above the speed limit—i.e.,
drivers traveling at 75 mph or more and at 80 mph or more. We also present the average
number of vehicles traveling above these speeds every day. Then, the table presents the
decrease in the number of vehicles relative to the number that were traveling at these
speeds before the MSMP was implemented.
A5-109
ATR-200—Enhanced Enforcement Period #4
Table 5.15 (a): ATR-200—Speed Data from the Fourth Enhanced Enforcement
Period Compared with Pre-MSMP Speed Data
Measure
Test Period
(5/22/06 to 7/16/06)
Decrease/Increase
Compared to One
Year Earlier
Mean (mph)
72.022757
-1.462134**
Percent in 10 mph
pace
62.71004
+7.81027**
0.909972
+0.006379*
0.709813
-0.005107*
0.313460
-0.089363**
0.037690
-0.107264**
0.003957
-0.043626**
2,567,419
2,646,530
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.15 (b): ATR-200—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(5/22/06 to 7/16/06)
6.68583*
72.646788
66.498095
77.963694
78.870247
79.776799
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-110
Table 5.16 (a): ATR-200—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Enhanced Enforcement Period #4 with Speed Data from One Year Earlier
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Test Period
(5/22/06 to 7/16/06)
Daily
Average in
Test Period
Decrease/
Increase
Compared to One
Year Earlier
804,782
14,371
-4,097
96,765
1,728
-4,918
2,567,419
45,847
—
Table 5.16 (b): ATR-200—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Enhanced Enforcement Period #4 with Speed Data from One Year Earlier
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Test Period
(5/22/06 to 7/16/06)
Daily
Average in
Test Period
Decrease/
Increase
Compared to One
Year Earlier
0.313460
0.313460
-0.089363
0.037690
0.037690
-0.107264
2,567,419
45,847
—
A5-111
ATR-200—Regular Enforcement Period #4
Table 5.17 (a): ATR-200—Speed Data from the Fourth Regular Enforcement Period
Compared with Speed Data from One Year Earlier
Measure
(One Week Only
7/17/06 to 7/24/06)
Decrease/Increase
Compared to
One Year Earlier
(All Four Weeks)
Mean (mph)
71.083293
-1.878825**
Percent in 10 mph
pace
58.79525
+1.38491*
0.884216
-0.010597*
0.693988
-0.037018*
0.314779
-0.093085**
0.039091
-0.057851*
0.003788
-0.018933*
336,601
1,297,731
Test Period
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 5.17 (b): ATR-200—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(One Week Only
7/17/06 to 7/24/06)
9.18993*
72.557798
65.899342
77.988504
78.8953246
79.802146
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-112
Table 5.18 (a): ATR-200—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph)
During Regular Enforcement Period #4 with Speed Data from One Year Earlier
Measure
Number of vehicles at
75 mph or more
Number of vehicles at
80 mph or more
Vehicle Total
Test Period
(One Week Only
7/17/06 to 7/24/06)
Daily
Average in
Test Period
Decrease/
Increase
Compared to One
Year Earlier
105,955
15,136
-4,476
13,158
1,880
-2,782
336,601
48,086
—
Table 5.18 (b): ATR-200—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 70 mph) During
Regular Enforcement Period #4 with Speed Data from One Year Earlier
Measure
Proportion of vehicles
at 75 mph or more
Proportion of vehicles
at 80 mph or more
Vehicle Total
Test Period
(One Week Only
7/17/06 to 7/24/06)
Daily
Average in
Test Period
Decrease/
Increase
Compared to One
Year Earlier
0.314779
0.314779
-0.093085
0.039091
0.039091
-0.057851
336,601
48,086
—
5.3. Overall Effect of the MSMP on Rural Freeways
In the Fourth MSMP Period, we obtained speed data from five ATRs and one Tube that
were located on Rural Freeways. [Unfortunately, the speed data for a second Tube were
collected from different lanes in the MSMP than in the Pre-MSMP period, as a result, the
comparison between the two time periods was compromised.] Four of the ATRs and the
Tube for which we had comparable data were located Within Enhanced Enforcement
Zones, while the fifth ATR was located Outside the Enhanced Enforcement Zones. At all
the ATR and Tube locations, the speed limit was unchanged—at 70 mph—during the
MSMP.
In order to provide a brief overall summary of the effect of the MSMP, we compared the
speed data obtained during the MSMP with speed data from previous years, focusing on
drivers traveling at least 10 mph above the speed limit—i.e., those traveling at 80 mph or
more. The speed data from two of the ATRs Within Enhanced Enforcement Zones
(ATR-175 and ATR-227) from the Northbound lanes of ATR-191 were reliable and were
combined. [The speed data from the ATR-208 were problematic—and these data were
omitted.] Table 5.19 shows the results of comparing data for the Fourth Enhanced
A5-113
Enforcement Period with speed data obtained one year earlier for ATR-175 and ATR227, and two years earlier for ATR-227.
Table 5.19: Effect of the MSMP at Three ATRs (ATR-175, ATR-191, and ATR227) Within Enhanced Enforcement Zones on Rural Freeways during the Fourth
Enhanced Enforcement Period
Sample Total
4,830,882*
Sample Total
2,465,892**
Pre-MSMP Data
# Over 80 mph
388,557*
Fourth Enhanced Enforcement Period
# Over 80 mph
123,430**
% Over 80 mph
8.04*
% Over 80 mph
5.01**
Result: 37.69% Reduction in Drivers Traveling over 80 mph
*Numbers adjusted to account for limited availability of data from ATR-227 (for four weeks only—as
opposed to eight weeks for both ATR-175 and ATR-191) during the pre-MSMP time period: Also, data for
ATR-175 and ATR-227 are from one year earlier; while data for ATR-191 are from two years earlier.
**Numbers are based on four weeks of speed data from all lanes for ATR-175 and ATR-227 and eight
weeks of data from the Northbound lanes for ATR-191
Table 5.19 indicates that, for three of the four ATRs Within Enhanced Enforcement
Zones on Rural Freeways, during the Fourth Enhanced Enforcement Period, there was a
37.69% decrease in the number of drivers traveling at over 80 mph—i.e., 10 mph over
the speed limit—as compared to the same calendar time period one (or two) years before
the MSMP was implemented.
A similar comparison was conducted for the Fourth Regular Enforcement Period—this
time with the addition of the speed data from Tube 06. Within the Enhanced
Enforcement Zones, the speed data from all lanes of ATR-175 and ATR-227, from the
Northbound lanes of ATR-191, and from Tube 06 were reliable—and these data were
combined. [Again, the speed data from ATR-208 were problematic—and, as a result,
were omitted. Table 5.20 shows the results of comparing the speed data from the Fourth
Regular Enforcement Period with speed data obtained one year earlier for ATR-175 and
ATR-227, two years earlier for ATR-227, and from one week during the month before
the MSMP was implemented for Tube 06.
A5-114
Table 5.20: Effect of the MSMP at Three ATRs (ATR-175, ATR-191, and ATR227) and One Tube Within Enhanced Enforcement Zones on Rural Freeways
During the Fourth Regular Enforcement Period
Sample Total
2,951,239*
Sample Total
3,010,699**
Pre-MSMP
# Over 80 mph
253,000*
Fourth Regular Enforcement Period
# Over 80 mph
158,033**
% Over 80 mph
8.57*
% Over 80 mph
5.25**
Result: 38.74% Reduction in Drivers Traveling over 80 mph
*Numbers adjusted to account for limited availability of data from Tube 06 (one week only—as opposed to
four weeks for ATR-175, ATR-191, and ATR-227): Also, data from Tube 06 are from the month prior to
the MSMP, data for ATR-175 and ATR-227 are from one year earlier, and data for ATR-191 are from two
years earlier.
** Numbers adjusted to account for limited availability of data from Tube 06 and ATR-227 (both one week
from all lanes), and ATR=191 (four weeks from Northbound lanes only)—as opposed to four weeks from
all lanes for ATR-175.
Table 5.20 indicates that, for the Tube and three of the four ATRs located Within
Enhanced Enforcement Zones on Rural Freeways, during the Fourth Regular
Enforcement Period, there was a 38.74% decrease in the number of drivers traveling over
80 mph—i.e., 10 mph over the speed limit.
We also examined the difference between the speed data obtained during the Test Periods
from the ATR that was located Outside the Enhanced Enforcement Zones. We focused
on drivers traveling at 80 mph or more—10 mph above the speed limit. The results of
this comparison for speed data obtained during the Fourth Enhanced Enforcement Period
are shown in Table 5.21.
Table 5.21: Effect of the MSMP on One ATR Outside the Enhanced Enforcement
Zones on a Rural Freeway During Fourth Enhanced Enforcement Period
Pre-MSMP Speed Data from 4/24/05 to 5/21/05
Sample Total
# Over 80 mph
% Over 80 mph
2,646,530
383,625
14.49
Fourth Enhanced Enforcement Period
Sample Total
# Over 80 mph
% Over 80 mph
2,567,419
96,765
3.77
Result: 73.98% Reduction in Drivers Traveling over 80 mph
Table 5.21 shows that, for the ATR located Outside Enhanced Enforcement Zones on a
Rural Freeway, during the Fourth Enhanced Enforcement Period, there was a 73.98%
decrease in the number of drivers traveling over 80 mph.
A5-115
A similar comparison was conducted for the Fourth Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 5.22.
Table 5.22: Effect of the MSMP at one ATR Outside the Enhanced Enforcement
Zones on a Rural Freeway During Fourth Regular Enforcement Period
Sample Total
1,297,731
Sample Total
336,601
One Year Before MSMP
# Over 80 mph
125,804
Fourth Regular Enforcement Period
# Over 80 mph
13,158
% Over 80 mph
9.69
% Over 80 mph
3.91
Result: 59.65% Reduction in Drivers Traveling over 80 mph
Table 5.22 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
a Rural Freeway, during the Fourth Regular Enforcement Period there was a 59.65%
decrease in the number of drivers traveling over 80 mph.
For Rural Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
Zones should be treated with caution. It should be noted that the ATR Outside the
Enhanced Enforcement Zones is located between two Enhanced Enforcement Zones on
the same freeway—one to the North-West and the other to the South-East. It is likely that
most drivers passing this ATR will have traveled through one or other of the Enhanced
Enforcement Zones. [It should also be noted that there are no other ATRs Outside the
Enhanced Enforcement Zones on Rural Freeways that could have been considered for
comparison purposes for this study.]
A5-116
Section 6. Speed Data Obtained on Urban Freeways
We obtained speed data from four ATRs located on Urban Freeways. Three of these
ATRs were located Within Enhanced Enforcement Zones, while the remaining ATR was
located Outside the Enhanced Enforcement Zones. During the MSMP, at the locations of
the three ATRs Within the Enhanced Enforcement Zones, the speed limit was increased
from 55 mph to 60 mph and there was Enhanced Enforcement at various times. In
contrast, at the location of the ATR Outside the Enhanced Enforcement, the speed limit
remained unchanged at 55 mph and there was no change in the level of enforcement
during the MSMP.
In this section of the report, for the ATRs located Within Enhanced Enforcement Zones
and the single ATR located Outside the Enhanced Enforcement Zones, we present
comparisons of the speed data obtained during the Test Year with speed data obtained at
those same ATRs before the MSMP was implemented.
It should be noted that, for the three ATRs Within Enhanced Enforcement Zones, there is
only very limited historical speed data. There are only speed data collected in the weeks
just before the MSMP began—specifically, the data are from September 2005 (with, in
two cases, data from the last two days in August, 2005). The available data are not the
same for all three ATRs—the actual time periods for which data were available are noted
in the comparison tables below. The result of comparing this August/September data with
the data collected at various times throughout the year should be considered with some
caution, as there may be seasonal effects that confound the effects of the MSMP.
There are historical speed data for the ATR located Outside the Enhanced Enforcement
Zones.
Comparisons using the speed data from the ATRs located Within Enhanced Enforcement
Zones are presented first. Then, we present comparisons using the speed data from the
ATR located Outside the Enhanced Enforcement Zones.
In making the comparisons between the speed data obtained during the Test Year and the
speed data obtained prior to the MSMP, we used two statistical tests. The first test was
used to examine differences in the mean speeds—for this we used the procedure for
comparing population means outlined by Kitchens (1987, p 369-373). The second test
was used to explore differences in the percentage of vehicles in the 10 mph pace and in
the differences in the proportions of vehicle traveling at various speeds. For this test, we
treated the distribution of speeds as a Bernoulli population—i.e., a population in which
each element is one of two possibilities, in this case, (1) in or out of the 10 mph pace, or
(2) above or below a selected speed (e.g., 75 mph). We then used the procedure for
comparing population proportions described by Kitchens (1987, pages 400-404).
Both statistical tests were conducted in two ways. First, the tests were conducted in the
traditional way, using n-values equal to the number of vehicles that traveled past each
A5-117
ATR in the time periods under consideration. Second, the tests were conducted using an
extremely conservative correction, with n-values equal to the number of hours in each
test period—the rationale for this was that it is possible, when traffic is congested, that
individual vehicles may travel at speeds which are not independent of each other.
6.1. Speed Data from ATRs located Within Enhanced Enforcement Zones
The three ATRs located Within Enhanced Enforcement Zones on Urban Freeways were
as follows: (1) ATR 100, on Highway 100 near Brooklyn Center in Hennepin County, (2)
ATR I94, on I-94 South of the 57th Street Bridge in Hennepin County, and (3) ATR35WCD, on I-35W, near Roseville in Ramsey County. At the locations of all three of
these ATRs, the speed limit was increased from 55 mph to 60 mph during the MSMP.
The effect of the MSMP on the speed data at each of these three ATRs is reported in this
section. It is reported ATR by ATR—with the effect of the MSMP in the Fourth
Enhanced Enforcement Period followed by its effect in the Fourth Regular Enhancement
Period.
For each of the three ATRs Within Enhanced Enforcement Zones, two tables are
presented for each time period. In the first of these tables, speed data from the Test Year
are compared with pre-MSMP speed data, which for these ATRs is limited to speed data
from September 2005 (and, in two cases, from the last two days in August, 2005)—the
specific dates from which data are available are noted in the table. In the second of the
tables for each ATR, the focus is on drivers traveling at least 5 mph and at least 10 mph
above the new speed limit adopted for the MSMP—i.e., on drivers traveling at 65 mph or
more and at 70 mph or more. In this second table, we present the number (and
proportion) of vehicles traveling above these speeds throughout the Fourth Enhanced
Enforcement Period or the Fourth Regular Enhancement Period. We also present the
average number of vehicles traveling above these speeds every day. Then, the table
presents the decrease in the number of vehicles relative to the number that were traveling
at these speeds before the MSMP. It should be noted that before the MSMP was adopted,
these speeds (of 65 mph or more and 70 mph or more) were 10 mph and 15 mph above
the pre-MSMP speed limit.
A5-118
ATR-100—Enhanced Enforcement Period #4
Table 6.1 (a): ATR-100—Comparison of Speed Data from the Fourth Enhanced
Enforcement Period with Speed Data from Two Weeks in September 2005
Measure
Test Period
(5/22/06 to 7/16/06)
Decrease/Increase
Compared to PreTest Period
(9/12/05 to 9/25/05)
Mean (mph)
57.43556
-3.135019**
Percent in 10 mph pace
47.7296
-9.79548**
0.193762
-0.089482**
0.059472
-0.032709**
0.012667
-0.012558*
0.004345
-0.002135*
0.001657
-0.000094*
4,190,825
1,089,474
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.1 (b): ATR-100—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(5/22/06 to 7/16/06)
12.74523*
60.19502
51.44693
66.62939
68.49103
71.01186
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-119
Table 6.2 (a): ATR-100—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #4 with Speed Data from Two Weeks
in September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(5/22/06 to 7/16/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
812,024
14,500
-6,696
249,237
4,451
-2,448
4,190,825
74,836
—
Table 6.2 (b): ATR-100—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Enhanced Enforcement Period #4 with Speed Data from Two Weeks in September
2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(5/22/06 to 7/16/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
0.193762
0.193762
-0.089482
0.059472
0.059472
-0.032709
4,190,825
74,836
—
A5-120
ATR-100—Regular Enforcement Period #4
Table 6.3 (a): ATR-100—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Speed Data from Two Weeks in September 2005
Measure
Test Period
(7/17/06 to 8/13/06)
Decrease/Increase
Compared to PreTest Period
(9/12/05 to 9/25/05)
Mean (mph)
59.05796
-1.512622**
Percent in 10 mph pace
57.3628
-0.1623*
0.231164
-0.052081*
0.042199
-0.049983**
0.008309
-0.016916**
0.002530
-0.003950*
0.000865
-0.000887*
2,171,636
1,089,474
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.3 (b): ATR-100—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to 8/13/06)
11.14386*
61.11503
55.15371
67.14758
68.47058
69.79358
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-121
Table 6.4 (a): ATR-100—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #4 with Speed Data from Two Weeks in
September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(7/17/06 to 8/13/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
502,003
17,929
-4,039
91,640
3,273
-3,877
2,171,636
77,558
—
Table 6.4 (b): ATR-100—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Regular Enforcement Period #4 with Speed Data from Two Weeks in September
2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(7/17/06 to 8/13/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
0.231164
0.231164
-0.052081
0.042199
0.042199
-0.049983
2,171,636
77,558
—
A5-122
ATR-I94—Enhanced Enforcement Period #4
Table 6.5 (a): ATR-I94—Comparison of Speed Data from the Fourth Enhanced
Enforcement Period with Speed Data from Four Weeks in August and September
2005
Measure
Test Period
(5/22/06 to 7/16/06)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
60.528599
-3.016248**
Percent in 10 mph pace
52.56242
-3.09561*
0.295999
-0.116799**
0.134484
-0.022438*
0.046374
-0.012603*
0.014193
-0.006049*
0.005635
-0.002934*
6,920,903
3,409,707
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.5 (b): ATR-I94—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(5/22/06 to 7/16/06)
10.99756*
61.239506
54.050764
69.519669
71.956865
74.794227
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-123
Table 6.6 (a): ATR-I94—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #4 with Speed Data from Four Weeks
in August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(5/22/06 to 7/16/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
2,048,577
36,582
-14,435
930,750
16,621
-2,773
6,920,903
123,588
—
Table 6.6 (b): ATR-I94—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Enhanced Enforcement Period #4 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(5/22/06 to 7/16/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
0.295999
0.295999
-0.116799
0.134484
0.134484
-0.022438
6,920,903
123,588
—
A5-124
ATR-I94—Regular Enforcement Period #4
Table 6.7 (a): ATR-I94—Comparison of Speed Data from the Fourth Regular
Enforcement Period with Speed Data from Four Weeks in August and September
2005
Measure
Test Period
(7/17/06 to 8/13/06)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
60.7925
-2.752343**
Percent in 10 mph pace
51.3229
-4.3351*
0.310969
-0.101828**
0.142493
-0.014429*
0.051926
-0.007051*
0.017438
-0.002804*
0.007556
-0.001013*
3,483,044
3,409,707
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.7 (b): ATR-I94—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to 8/13/06)
11.18971*
61.51712
54.29063
69.77721
72.34596
75.27928
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-125
Table 6.8 (a): ATR-I94—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #4 with Speed Data from Four Weeks in
August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(7/17/06 to 8/13/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
1,083,119
38,683
-12,667
496,310
17,725
-1,795
3,483,044
124,394
—
Table 6.8 (b): ATR-I94—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Regular Enforcement Period #4 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(7/17/06 to 8/13/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
0.310969
0.310969
-0.101828
0.142493
0.142493
-0.014429
3,483,044
124,394
—
A5-126
ATR-35WCD—Enhanced Enforcement Period #4
Table 6.9 (a): ATR-35WCD—Comparison of Speed Data from the Fourth Enhanced
Enforcement Period with Speed Data from Four Weeks in August and September
2005
Measure
Test Period
(5/22/06 to 7/16/06)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
59.954351
-0.053425**
Percent in 10 mph pace
42.36333
-5.92408**
0.380191
+0.028343*
0.121613
+0.004159*
0.030092
+0.003758*
0.0077817
+0.002588*
0.002268
+0.001079*
6,051,928
3,030,663
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.9 (b): ATR-35WCD—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(5/22/06 to 7/16/06)
12.82659*
62.619589
52.418260
69.451094
71.180759
73.912355
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-127
6.10 (a): ATR-35WCD—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #4 with Speed Data from Four Weeks
in August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(5/22/06 to 7/16/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
2,300,889
41,087
+3,063
735,993
13,143
+449
6,051,928
108,070
—
Table 6.10 (b): ATR-35WCD—Comparison of the Proportion of Vehicles Traveling
at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Enhanced Enforcement Period #4 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(5/22/06 to 7/16/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
0.380191
0.380191
+0.028343
0.121613
0.121613
+0.004159
6,051,928
108,070
—
A5-128
ATR-35WCD—Regular Enforcement Period #4
Table 6.11 (a): ATR-35WCD —Comparison of Speed Data from the Fourth Regular
Enforcement Period with Speed Data from Four Weeks in August and September
2005
Measure
Test Period
(7/17/06 to 8/13/06)
Decrease/Increase
Compared to
Pre-Test Period
(8/29/05 to 9/25/05)
Mean (mph)
60.82319
+0.815410**
Percent in 10 mph pace
43.1412
-5.1462*
0.413005
+0.061156**
0.137981
+0.020526*
0.035197
+0.008864*
0.009263
+0.004069*
0.002726
+0.001538
3,103,414
3,030,663
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.11 (b): ATR-35WCD—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
th
15 percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to 8/13/06)
12.34333*
63.24184
53.53127
69.78148
71.84761
74.27991
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-129
Table 6.12 (a): ATR-35WCD—Comparison of the Daily Average Number of
Vehicles Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit
(of 60 mph) During Regular Enforcement Period #4 with Speed Data from Four
Weeks in August and September 2005
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(7/17/06 to 8/13/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
1,281,724
45,776
+6,778
428,211
15,293
+2,275
3,103,414
110,836
—
Table 6.12 (b): ATR-35WCD—Comparison of the Proportion of Vehicles Traveling
at Least 5 mph and at Least 10 mph Above the Speed Limit (of 60 mph) During
Regular Enforcement Period #4 with Speed Data from Four Weeks in August and
September 2005
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(7/17/06 to 8/13/06)
Daily
Average in
Test Period
Decrease/Increase
Compared to Pre-Test
Period
(9/12/05 to 9/25/05)
0.413005
0.413005
+0.061156
0.137981
0.137981
+0.020526
3,103,414
110,836
—
A5-130
6.2. Speed Data from the ATR located Outside Enhanced Enforcement Zones
There was one ATRs that was located on an Urban Freeway Outside the Enhanced
Enforcement Zones. It was ATR-335, on I-35W at County Road 53 in Anoka County.
During the MSMP, at this ATR location the speed limit remained unchanged at 55 mph
and there were no changes in enforcement. For ATR-335, the speed data obtained during
2005, when the MSMP occurred, was compared with historical speed data. Comparisons
are presented for the eight-week time period between 2/27 and 4/23, when the Fourth
Enhanced Enforcement Period occurred during the MSMP, and then for the four-week
time period between 4/24 and 5/21, when the Fourth Regular Enhancement Period
occurred.
Two tables are presented for each of these time periods. In the first table, speed data
from the Test Year are compared with the historical speed data. We include speed data
from two and three before the MSMP in this table—unfortunately, the speed data from
the year before were unreliable for both time periods. In the second table, the focus is on
drivers who were traveling at least 5 mph and at least 10 mph above the new speed limit
adopted for the MSMP—i.e., drivers traveling at 65 mph or more and at 70 mph or more.
It should be noted that, during and before the MSMP, these speeds (65 mph or more and
70 mph or more) were 10 mph and 15 mph above the actual speed limit at the location of
ATR-335. In this second table, we present the number (and proportion) of vehicles
traveling above these speeds throughout the Fourth Enhanced Enforcement Period and
the Fourth Regular Enhancement Period. We also present the average number of
vehicles traveling above these speeds each day. Then, the table presents the decrease in
the number of vehicles relative to the number that were traveling at these speeds before
the MSMP was implemented.
A5-131
ATR-335—Enhanced Enforcement Period #4
Table 6.13 (a): ATR-335—Speed Data from the Fourth Enhanced Enforcement
Period Compared with Speed Data from Two Prior Years
Measure
Test Period
(Four Weeks Only
06/05/06 to 06/11/06
and
06/26/06 to 07/16/03)
(Four Weeks Only)
Decrease/
Increase as
Compared to
Three Years
Earlier
(All Eight Weeks)
Mean (mph)
70.772184
+0.024394**
-1.090665**
Percent in 10
mph pace
57.521283
-4.02926**
+3.73936*
0.859794
+0.009495*
+0.021358*
0.575258
-0.020005*
-0.053161**
0.269107
+0.050534**
-0.016947*
0.084769
+0.012773*
-0.030355**
0.026198
+0.010551*
-0.010530*
1,336,806
1,515,990
2,571,918
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
Decrease/
Increase as
Compared to Two
Years Earlier
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.13 (b): ATR-335—Additional Speed Data from Enhanced Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(Four Weeks Only
06/05/06 to 06/11/06
and
06/26/06 to 07/16/03)
9.510916*
71.229106
65.172108
78.230674
79.586879
82.968128
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-132
Table 6.14 (a): ATR-335—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Enhanced Enforcement Period #4 and Speed Data from Two and
Three Years Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Test Period
(06/05/06 to
06/11/06
and
06/26/06 to
07/16/03)
(Four Weeks
Only)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
1,149,378
41,049
+453
+1,020
769,009
27,465
-955
-2,538
1,336,806
47,743
—
—
Table 6.14 (b): ATR-335—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Enhanced Enforcement Period #4 and Speed Data from Two and Three Years
Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Test Period
(06/05/06 to
06/11/06
and
06/26/06 to
07/16/03)
(Four Weeks
Only)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
Decrease/
Increase
Compared
to Three
Years
Earlier
0.859794
0.859794
+0.009495
+0.021358
0.575258
0.575258
-0.020005
-0.053161
1,336,806
47,743
—
—
A5-133
ATR-335—Regular Enforcement Period #4
Table 6.15 (a): ATR-335—Speed Data from the Fourth Regular Enforcement Period
Compared with Speed Data from Two Prior Years
Measure
Test Period
(7/17/06 to
8/13/06)
Decrease/
Increase as
Compared to
Two Years
Earlier
Decrease/
Increase as
Compared to
Three Years
Earlier
Mean (mph)
70.11449
-1.293582**
-1.093504**
Percent in 10
mph pace
54.85502
-4.55272*
-2.14225*
0.833713
-0.037315*
-0.001309*
0.567233
-0.061750**
-0.024566*
0.283369
0.025243*
0.036708*
0.095189
0.012265*
0.015643*
0.030703
0.013647*
0.003398*
1,405,127
1,470,983
1,335,728
Proportion at
65 mph or more
Proportion at
70 mph or more
Proportion at
75 mph or more
Proportion at
80 mph or more
Proportion at
85 mph or more
Vehicle Total
**Statistically significant using the highly conservative correction.
*Statistically significant using the statistical tests in the traditional way.
Table 6.15 (b): ATR-335—Additional Speed Data from Regular Enforcement
Period #4
Measure
Standard deviation (mph)
Median (mph)
15th percentile (mph)
85th percentile (mph)
90th percentile (mph)
95th percentile (mph)
Test Period
(7/17/06 to 8/13/06)
11.44632*
71.18424
64.10925
78.54365
79.87216
83.50375
*Statistical comparisons of standard deviations are rarely performed—such a comparison was not
necessary for this project.
[Please Note: Statistical comparisons are inherently unreliable for the other measures in this Table because
the speed data are collected in 5-mph and 15-mph bins and no differentiation within bins is possible.]
A5-134
Table 6.16 (a): ATR-335—Comparison of the Daily Average Number of Vehicles
Traveling at Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60
mph) During Regular Enforcement Period #4 and Speed Data from Two and Three
Years Earlier
Measure
Number of vehicles at
65 mph or more
Number of vehicles at
70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(7/17/06 to
8/13/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
1,171,472
41,838
-1,873
-66
797,034
28,466
-3,099
-1,233
1,405,127
50,183
—
—
Table 6.16 (b): ATR-335—Comparison of the Proportion of Vehicles Traveling at
Least 5 mph and at Least 10 mph Above the New Speed Limit (of 60 mph) During
Regular Enforcement Period #4 and Speed Data from Two and Three Years Earlier
Measure
Proportion of vehicles
at 65 mph or more
Proportion of vehicles
at 70 mph or more
Vehicle Total
Decrease/
Increase
Compared
to Three
Years
Earlier
Test Period
(7/17/06 to
8/13/06)
Daily
Average
in Test
Period
Decrease/
Increase
Compared
to Two
Years
Earlier
0.833713
0.833713
-0.037315
-0.001309
0.567233
0.567233
-0.061750
-0.024566
1,405,127
50,183
—
—
6.3. Overall Effect of the MSMP on Urban Freeways
In the MSMP, we obtained speed data from four ATRs located on Urban Freeways—
three of these ATRs were located Within Enhanced Enforcement Zones, while the
remaining ATR was located Outside the Enhanced Enforcement Zones. The speed limit
was increased from 55 mph to 60 mph at the locations of the three ATRs Within
Enhanced Enforcement Zones, while the speed limit remained unchanged at 55 mph at
location of the ATR Outside the Enhanced Enforcement Zones.
In order to provide a brief overall summary of the effect of the MSMP, speed data from
the three ATRs Within Enhanced Enforcement Zones were combined. For this summary,
we focused on drivers traveling at least 10 mph above the new speed limit. Then, we
A5-135
compared speed data collected during the Fourth Enhanced Enforcement Period with preMSMP speed data collected just before the MSMP began—these data were collected over
two weeks in September 2005 for ATR-100, and over four weeks in August and
September 2005 for ATR-I94 and ATR-35WCD. When the pre-MSMP data were
collected the speed limit at the locations of the three ATRs was still 55 mph. Table 6.17
shows the results of this comparison for the Fourth Enhanced Enforcement Period.
Table 6.17: Effect of the MSMP at Three ATRs Within Enhanced Enforcement
Zones on Urban Freeways During the Fourth Enhanced Enforcement Period
Sample Total
8,619,318*
Sample Total
17,163,656
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879*
Fourth Enhanced Enforcement Period
# Over 70 mph
1,915,980
% Over 70 mph
12.67*
% Over 70 mph
11.16
Result: 11.92% Reduction in Drivers Traveling over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-100 (for two weeks only—as
opposed to four weeks for both ATR-I94 and ATR-35WCD) during the pre-MSMP time period.
Table 6.17 indicates that, for the three ATRs Within Enhanced Enforcement Zones on
Urban Freeways, during the Fourth Enhanced Enforcement Period, there was a 11.92%
decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the new
speed limit—as compared to the month before the MSMP was implemented.
A similar comparison was conducted for the Fourth Regular Enforcement Period. The
results of this comparison using speed data from the three ATRs are shown in Table 6.18.
Table 6.18: Effect of the MSMP at Three ATRs Within Enhanced Enforcement
Zones on Urban Freeways During the Fourth Regular Enforcement Period
Sample Total
8,619,318*
Sample Total
8,758,094
Before MSMP—Aug/Sept 05
# Over 70 mph
1,091,879*
Fourth Regular Enforcement Period
# Over 70 mph
1,016,161
% Over 70 mph
12.67*
% Over 70 mph
11.60
Result: 8.45% Reduction in Drivers Traveling over 70 mph
*Numbers adjusted to account for limited availability of data from ATR-100 (for two weeks only—as
opposed to four weeks for both ATR-I94 and ATR-35WCD) during the pre-MSMP time period.
Table 6.18 indicates that, for the three ATRs located Within Enhanced Enforcement
Zones on Urban Freeways, during the Fourth Regular Enforcement Period, there was a
A5-136
8.45% decrease in the number of drivers traveling over 70 mph—i.e., 10 mph over the
new speed limit—as compared to the month before the MSMP was implemented.
We also examined the difference between the speed data obtained during the Test Periods
from the ATR that was located Outside the Enhanced Enforcement Zones. For this ATR
location there was no change in the level of enforcement during the MSMP and no
change in the speed limit. For comparison purposes, we focused on drivers traveling at
70 mph or more—while this is 10 mph above the new speed limit Within Enhanced
Enforcement Zones, it is 15 mph above the actual speed limit at the location of the ATR
Outside Enhanced Enforcement Zones. The results of this comparison for speed data
obtained during the Fourth Enhanced Enforcement Period with Pre-MSMP speed data are
shown in Table 6.19. It should be noted that, because of the unreliability of the data from
the prior year the Pre-MSMP data are from two years earlier.
Table 6.19: Effect of the MSMP at One ATR Outside the Enhanced Enforcement
Zones on an Urban Freeway During the Fourth Enhanced Enforcement Period
Sample Total
1,515,990*
Sample Total
1,336,806
Pre-MSMP
# Over 70 mph
902,413*
Fourth Enhanced Enforcement Period
# Over70 mph
769,009
% Over 70 mph
59.53*
% Over 70 mph
57.53
Result: 3.36% Reduction in Drivers Traveling over 70 mph
*Data for ATR-353 are from two years earlier.
Table 6.19 shows that, for the ATR located Outside Enhanced Enforcement Zones on an
Urban freeway, during the Fourth Enhanced Enforcement Period, there was a 3.36%
decrease in the number of drivers traveling over 70 mph—i.e., 10 mph above the new
speed limit Within Enhanced Enforcement Zones (and 15 mph above the current speed
limit Outside the Enhanced Enforcement Zones).
A similar comparison was conducted for the Fourth Regular Enforcement Period. The
results of this comparison using speed data from the ATR located Outside the Enhanced
Enforcement Zones are shown in Table 6.20. Again, it should be noted that, because of
the unreliability of the data from the prior year the Pre-MSMP data are from two years
earlier.
A5-137
Table 6.20: Effect of the MSMP at One ATR Outside the Enhanced Enforcement
Zones on an Urban Freeway During the Fourth Regular Enforcement Period
Sample Total
1,470,983*
Sample Total
1,405,127
Pre-MSMP
# Over 70 mph
925,333*
Fourth Regular Enforcement Period
# Over 70 mph
797,034
% Over 70 mph
62.91*
% Over 70 mph
56.72
Result: 9.84% Reduction in Drivers Traveling over 70 mph
*Data for ATR-353 are from two years earlier.
Table 6.20 shows that, for the ATR located Outside the Enhanced Enforcement Zones on
an Urban Freeway, during the Fourth Regular Enforcement Period there was a 9.84%
decrease in the number of drivers traveling over 70 mph—i.e., at 10 mph or more above
the new speed limit Within Enhanced Enforcement Zones (and 15 mph or more above the
current speed limit Outside Enhanced Enforcement Zones).
For Urban Freeways, comparisons between speed data from the ATRs located Within
Enhanced Enforcement Zones and the ATR located Outside the Enhanced Enforcement
Zones should be treated with caution. It should be noted that the location of ATR that
was located Outside the Enhanced Enforcement Zones is only a few miles to the North of
an Enforced Enforcement Zone. And, most of the drivers traveling North past this ATR
will have traveled through that Enhanced Enforcement Zone. [It should also be noted
that, the locations of all the other ATRs Outside the Enhanced Enforcement Zones on
Urban Freeways that might have been considered for comparison purposes for this study
are also very close to Enhanced Enforcement Zones.] Also, as already mentioned, for the
ATR located Outside the Enhanced Enforcement Zones, because of the unreliability of
the data from the prior year the Pre-MSMP data are from two years earlier for both the
Fourth Enhanced and Regular Enforcement Periods.
A5-138
Section 7. Crash Data
During the MSMP Test Period, crash data were available for all Minnesota trunk
highways. These trunk highways included 2-Lane/2-Way Highways, 4-Lane Highways,
Rural Freeways, and Urban Highways. Some of the highways had changed speed limits
during the MSMP, some had enhanced enforcement during the MSMP, and speed data
were available from some of them. In all, there were twelve combinations of Road Type,
Speed Limits, and Enforcement Status. Table 7.1 lists the twelve combinations—along
with the availability of speed data and the total length of roadway for each combination.
Table 7.1: Combinations of Trunk Highway Type, Speed Limits During the MSMP,
and Enforcement Status (with Availability of Speed Data and Length of Roadway)
Type of
Roadway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
2-Lane/2-Way
Highway
Speed Limits
Increased—from 55
mph to 60 mph
Unchanged at 55
mph
Increased—from 55
mph to 60 mph
4-Lane Divided
Highway
4-Lane Divided
Highway
Unchanged at 65
mph
Unchanged at 65
mph
Rural Freeway
Unchanged at 70
mph
Unchanged at 70
mph
Rural Freeway
Urban Freeway
Urban Freeway
Urban Freeway
Urban Freeway
Urban Freeway
Increased—from 55
mph to 60 mph
Unchanged at 55
mph
Unchanged at 60
mph
Unchanged at 60
mph
Unchanged at 55
mph
Enforcement
Status
(Within/Outside
Enhanced
Enforcement
Zone)
Within
Outside
Outside
Within
Outside
Availability of
Speed Data
Available/
Unavailable
Available
(ATR & Tube)
Available
(ATR)
Available
(Tube)
Total Length of
Highways
Segments
(in Miles)
316.790
Available
(ATR & Tube)
Available
(ATR)
52.219
7,593.783
474.511
550.525
Available
(ATR & Tube)
Available
(ATR)
265.246
27.337
89.397
Within
Available
(ATR)
Available
(ATR)
Unavailable
Outside
Unavailable
73.377
Within
Unavailable
11.234
Within
Outside
Within
Outside
A5-139
459.835
4.052
Table 7.1 shows that crash data were available from all the combinations for which speed
data were available, as well as from three combinations for which we did not have speed
data. The table also shows that there were great differences in the length of roadway in
each combination—the range was from 7,593.783 miles of 2-Lane/2-Way Highway, with
unchanged speed limits, that were outside the enhanced enforcement zones to 4.052 miles
of Urban Freeway, with unchanged speed limits, that were within the enhanced
enforcement zones.
While an enormous amount of speed data were available for analysis purposes, in
contrast there were orders of magnitude less crash data. Crash data become more stable
as the sample size increases—for that reason, instead of analyzing them over individual
road segments, we analyzed the crash data in terms of the twelve combinations listed in
Table 7.1. Also, we combined the crash data from the First, Second, Third, and Fourth
Enhanced Enforcement Periods with the crash data from the First, Second, Third, and
Fourth Regular Enforcement Periods. In Tables 7.2 through 7.13, we present the crash
data from the First, Second, Third, and Fourth MSMP Test Period so that it can be
compared with historical crash data taken from the same time period (i.e., between 9/26
and 8/13) over the previous five years. However, please note that the Average Daily
Traffic (ADT) values used for the MSMP Period in Tables 7.2 through 7.13 are ADT
values calculated for traffic levels on the various highways in 2005—this is because ADT
values for 2006 will not be available until 2007. Also, please note that the number of
days over which the data were collected was 322 (46 weeks) for the MSMP period and
1,611 days for the same period over the last five year—i.e., 322 multiplied by five (years)
plus 1 day (because 2004 was a leap year).
Table 7.2: Crash Data for 2-Lane/2-Way Highways for which the Speed Limit Was
Increased, from 55 mph to 60 mph, and that Were Within the Enhanced
Enforcement Zones during the MSMP
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 8/13/06)
316.790
3,959.0038
322
5
8
36
Historical Crash
Data
316.790
3,888.6784
1,611*(leap year)
29
55
155
69
200
160
874
278
0.6884
1.1465
1.2381
1,313
0.6616
1.0602
1.4613
A5-140
7.3: Crash Data for 2-Lane/2-Way Highways for which the Speed Limit Was
Unchanged, at 55 mph, and that Were Outside the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 8/13/06)
7,593.783
2,539.9186
322
88
136
562
Historical Crash
Data
7,593.783
2,481.7046
1,611*(leap year)
481
777
3,666
1,019
4,832
3,220
17,937
5,025
0.8091
1.2765
1.4169
27,693
0.9121
1.4530
1.5843
Table 7.4: Crash Data for 2-Lane/2-Way Highways for which the Speed Limit Was
Increased, from 55 mph to 60 mph, and that Were Outside the Enhanced
Enforcement Zones during the MSMP
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 8/13/06)
474.511
2,745.0887
322
4
2
24
Historical Crash
Data
474.511
2,718.1379
1,611*(leap year)
24
40
159
47
186
138
670
215
0.5126
0.7916
0.9537
1,079
0.5193
0.8658
1.1550
A5-141
Table 7.5: Crash Data for 4-Lane Divided Highways for which the Speed Limit Was
Unchanged, at 65 mph, and that Were Within the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 8/13/06)
52.219
16,844.8455
322
1
4
13
Historical Crash
Data
52.219
16,084.2619
1,611*(leap year)
17
24
101
31
215
108
653
157
0.5543
0.8120
0.3531
1,010
0.7464
1.1581
1.2564
Table 7.6: Crash Data for 4-Lane Divided Highways for which the Speed Limit Was
Unchanged, at 65 mph, and that Were Outside the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 8/13/06)
550.525
12,279.2783
322
14
24
129
Historical Crash
Data
550.525
11,815.7785
1,611*(leap year)
86
162
943
296
1459
972
5,324
1,435
0.6592
0.9726
0.6432
7,974
0.7609
1.1593
0.8207
A5-142
Table 7.7: Crash Data for Rural Freeways for which the Speed Limit Was
Unchanged, at 70 mph, and that Were Within the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 8/13/06)
265.246
21,345.3377
322
10
15
110
Historical Crash
Data
265.246
20,247.5510
1,611*(leap year)
65
93
498
165
842
874
4,183
1,174
0.6440
0.9018
0.5485
5,681
0.6566
0.9313
0.7513
Table 7.8: Crash Data for Rural Freeways for which the Speed Limit Was
Unchanged, at 70 mph, and that Were Outside the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 8/13/06)
459.835
22,663.6713
322
12
25
158
Historical Crash
Data
459.835
21,809.3573
1,611*(leap year)
87
102
928
345
1,593
1,383
7,111
1,923
0.5730
0.8067
0.3576
9,821
0.6079
0.8618
0.5385
A5-143
Table 7.9: Crash Data for Urban Freeways for which the Speed Limit Was
Increased, from 55 mph to 60 mph, and that Were Within the Enhanced
Enforcement Zones during the MSMP
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 8/13/06)
27.337
102,733.2401
322
2
7
47
Historical Crash
Data
27.337
101,270.2829
1,611*(leap year)
19
47
301
187
839
565
3,326
808
0.8935
1.2363
0.2212
4,532
1.0162
1.3879
0.4260
Table 7.10: Crash Data for Urban freeways for which the Speed Limit Was
Unchanged, at 55 mph, and that Were Outside the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 8/13/06)
89.397
90,578.2219
322
10
9
126
Historical Crash
Data
89.397
89,933.0580
1,611*(leap year)
41
93
956
735
3,508
2,737
15,870
3,617
1.3872
1.7915
0.3835
20,468
1.5803
2.0330
0.3166
A5-144
Table 7.11: Crash Data for Urban Freeways for which the Speed Limit Was
Unchanged, at 60 mph, and that Were Within the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 8/13/06)
4.052
97,906.2409
322
0
3
7
Historical Crash
Data
4.052
96,577.3572
1,611*(leap year)
4
4
44
19
109
85
513
114
0.8924
1.2212
0.0000
674
1.0691
1.4260
0.6345
Table 7.12: Crash Data for Urban Freeways for which the Speed Limit Was
Unchanged, at 60 mph, and that Were Outside the Enhanced Enforcement Zones
during the MSMP
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 8/13/06)
73.377
91,627.8252
322
4
11
89
Historical Crash
Data
73.377
93,212.0278
1,611*(leap year)
26
52
638
393
1,936
1,439
8,436
1,936
0.8943
1.1806
0.1848
11,088
1.0063
1.3214
0.2360
A5-145
Table 7.13: Crash Data for Urban Freeways that Were Within the Enhanced
Enforcement Zones during the MSMP but Had Unchanged Speed Limits
Length (miles)
Average Daily Traffic
Days in Period
Number of Fatal Crashes
Number of A Injury Crashes
Number of B Injury Crashes
Number of C Injury Crashes
and Unknowns
Number of Property Damage
Crashes
Total Crashes
Crash Rate
Severity Rate
Fatal Crash Rate
Test Period
(9/26/05 to 8/13/06)
11.234
128,504.4084
322
2
2
19
Historical Crash
Data
11.234
126,383.5665
1,611*(leap year)
11
10
173
148
732
453
2,697
624
1.3424
1.7726
0.4303
3,623
1.5840
2.0876
0.4809
The crash data presented in Tables 7.2 through 7.13 are summarized below in Table 7.14.
The table shows the Crash Rate, the Severity Rate, and the Fatal Crash Rate for each
combination of road type, speed limit condition both Within and Outside the Enforcement
Zones between 9/26/05 and 8/13/06 (the 46 weeks of the MSMP).
Table 7.14: Crash Rate, Severity Rate, and Fatal Crash Rate for Each Combination
of Trunk Highway Type, Speed Limits During the MSMP, and Enforcement Zone
During the 46 Weeks of the MSMP
Within
Road Type/Speed Limit
2 Lane/2-Way Highway
Increase—55 to 60 mph
2 Lane/2-Way Highway
No Change—55 mph
4 Lane/Divided Highway
No Change—65 mph
Rural Freeway
Unchanged—70 mph
Urban Freeway
Increase—55 to 60 mph
Urban Freeway
No Change—55 mph
Urban Freeway
No Change—60 mph
Outside
Crash
Rate
Severity
Rate
Fatal
Crash
Rate
0.6884
1.1465
1.2381
0.5126
0.7916
0.9537
—
—
—
0.8091
1.2765
1.4169
0.5543
0.8120
0.3531
0.6592
0.9726
0.6432
0.6440
0.9018
0.5485
0.5730
0.8067
0.3576
0.8935
1.2363
0.2212
—
—
—
1.3424
1.7726
0.4303
1.3872
1.7915
0.3835
0.8924
1.2212
0.0000
0.8943
1.1848
0.1848
A5-146
Crash
Rate
Severity
Rate
Fatal
Crash
Rate
Section 8. Citation Data
During the Fourth MSMP Enhanced Enforcement Period citation data were collected for
the highways on which there was Enhanced Enforcement. In all, citation data were
collected for 32 regions—14 of these regions have ATRs in them; while seven had Tubes
in the Fourth Enhanced Enforcement Period; and the remaining eleven are next to regions
where there are ATRs or Tubes. The citation data for the 14 regions in which there are
ATRs and seven regions in which there were Tubes are reported in the tables below;
there is one table for each road type included in the MSMP—i.e., 2-Lane/2-Way
Highways, 4-Lane Highways, Rural Freeways, and Urban Highways. The tables list the
ATRs and Tubes that were on the various road types and their locations. The Tables also
present the Number of Speed Citations and the Number of Speed Warnings given during
the Fourth Enhanced Enforcement Period, the Number of Vehicles that were Stopped and
the Number of Hours of Enforcement.
Table 8.1: Citation Data for 2-Lane/2-Way Highways on Which ATRs and Tubes
Were Located
ATR/
Tube
ATR-210
ATR-219
ATR-220
Tube 01
Tube 02
Tube 03
Tube 04
Total
Location
US-71, 1 m. North of
Blackduck, Beltrami
US-2, South East of
Warba, Itasca
US-71, South of CR 89,
Hubbard
MN-23, Hanley Falls,
Lyon
MN-7, Montevideo,
Chippewa
US-71, Willmar,
Kandiyohi
MN-7, Silver Lake,
McLeod
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
181
816
1,022
456
291
538
871
432
130
422
601
240
76
624
743
268
121
346
519
274
124
536
754
294
187
265
568
181
1,110
3,547
5,078
2,145
A5-147
Table 8.2: Citation Data for 4-Lane Divided Highways on Which ATRs and Tubes
Were Located
ATR/
Tube
ATR-197
Location
US-10, West of
Dilworth, Clay
US-10, 0.8 miles West
of Rice, Benton
US-52, North of
Rochester, Olmstead
SR-60, 0.7 miles West
of junction with SR-4,
(St. James) Watonwan
Tube 05
MN-60, Lake Crystal,
Blue Earth
ATR-172
ATR-187
ATR-188
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
39
101
151
132
292
307
654
294
172
300
534
327.5
171
380
551*
181
138
353
551
181
812
1,441
2,441*
1,115.5
Total
*Adjusted, but still probably an underestimate
Table 8.3: Citation Data for Rural Freeways on Which ATRs and Tubes Were
Located
ATR/
Tube
ATR-175
ATR-191
ATR-208
ATR-227
Tube 06
Tube 07
Total
Location
I-94, 0.5 miles South
East of Saulk Centre,
Stearns
I-35, North of
Wyoming, Chisago
I-35, North of
Owatanna, Steele
I-90, East of Alden,
Freeborn
I-94, Fergus Falls,
Otter Tail
I-35, Cloquet,
Carlton
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
435
326
821
294
171
239
499
56
257
721
1,019
327.5
78
107
200
315.5
71
162
283
136
137
348
530
366
1,149
1,903
3,352
1,495
A5-148
Table 8.4: Citation Data for Urban Freeways on Which ATRs Were Located
ATR
100
I94
35WCD
Location
Highway 100, near
Brooklyn Center,
Hennepin
I-94, South of 57th
Street Bridge,
Hennepin
I-35W, near Roseville,
Ramsey
Number of
Speed
Citations
Number of
Speed
Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
605
392
1,114
409
437
315
819
409
1,684
801
2,637
869
2,276
1,508
4,570
1,687
Total
The citation data for the individual highways that are presented in Tables 8.1 through 8.4
are summarized in Table 8.5. This table presents, for each of the four highway types, the
Number of Speed Citations and the Number of Speed Warnings that were given during
the Fourth Enhanced Enforcement Period, as well as the Number of Vehicles that were
Stopped and the Number of Hours of Enforcement.
Table 8.5: Citation Data for the Four Types of Highways on Which ATRs and
Tubes Were Located
Type of Highway
2-Lane/2-Way
Highway
4-Lane Divided
Highway
Rural Freeway
Urban Freeway
Total
Number of
Speed Citations
Number of
Speed Warnings
Number of
Vehicles
Stopped
Hours of
Enforcement
1,110
3,547
5,078
2,145
812
1,149
2,276
1,441
1,903
1,508
2,441*
3,352
4,570
1,115.5
1,495
1,687
5,347
8,399
15,441
6,442.5
*Adjusted, but still probably an underestimate
A5-149