ROAD SAFETY AUDIT
MAJOR HIGHWAY MEDIAN
CROSS-OVER CRASHES
I-495 Chelmsford
495
Prepared for
Massachusetts Highway Department
Prepared by
MS Transportation Systems, Inc.
Framingham, Massachusetts
February 2009
ROAD SAFETY AUDIT
MAJOR HIGHWAY MEDIAN
CROSS-OVER CRASHES
I-495 CHELMSFORD
FINAL REPORT
February 2009
Prepared for
Massachusetts Highway Department
Prepared by
MS Transportation Systems, Inc.
Consulting Engineers and Planners
300 Howard Street, P.O. Box 967
Framingham, Massachusetts 01701
Tel: (508) 620-2832 Fax: (508) 620-6897
www.mstransportationsystemsinc.com
I-495 Chelmsford Road Safety Audit
TABLE OF CONTENTS
Page
INTRODUCTION
1
RSA PROCESS
3
ANALYSIS
7
SUMMARY OF RSA FINDINGS/POTENTIAL ACTIONS
10
RECOMMENDATIONS
15
APPENDIX
19
MS Transportation Systems, Inc.
I-495 Chelmsford Road Safety Audit
INTRODUCTION
Lane departure crashes are one of the primary fatal crash types in Massachusetts. The
Commonwealth exceeds the national average for lane departure crashes and was
designated a lead state in lane departure crashes by the American Association of State
Highway and Transportation Officials (AASHTO).
The Massachusetts Highway
Department (MHD) conducted a study of the problem and found that during 2002-2004,
lane departure crashes accounted for 25 percent of all injury crashes and nearly half, 46
percent, of all fatal crashes.
As part of the effort in implementing the safety plan and specifically reducing lane
departure crashes, MassHighway is completing a Road Safety Audit (RSA) Review
Project specifically focused on median crossing (or median cross-over) crashes on its
major highways. Road safety audits are a formal safety performance examination on
existing or future roadways by an independent audit team. These specific audits are
being conducted in locations where cross-over experience has been or has the potential
to be of concern and where the RSA team has judged that factors exist and safety risk
could be affected. The team works to identify opportunities for enhancing safety and to
recommend specific enhancements that may be implemented to reduce median crossover crashes and improve the overall safety along the highway.
An RSA was conducted for the I-495 in Chelmsford as part of this overall effort. The
roadway section under study, shown in Figure 1, was essentially between Interchange
No. 32 at Boston Road and Interchange No. 34 at Route 110 a distance of
approximately 4.2 miles. This section had experienced a fatal cross-median crash.
The purpose of this I-495 Chelmsford RSA was to assess current safety characteristics
on the highway section under study and to recommend a set of actions to enhance the
safe operation of the highway section under study. Recommendations contained in this
report reflect the overall consent of the RSA team and do not necessarily reflect the
official views of MassHighway.
MS Transportation Systems, Inc.
Page 1
Lowell
Connector
Route 3
Interchange
33
Interchange
34
Interchanges
35 & 36
495
Route 4
Route 110
Chelmsford
Interchange
32
495
Boston Road
Westford
N
Project Location
W
S
Interstate 495 Road Safety Audit
Chelmsford, Massachusetts
MS Transportation Systems, Inc.
E
1 : 25,000
Framingham, Massachusetts
FIGURE 1
I-495 Chelmsford Road Safety Audit
RSA PROCESS
In conducting the RSA, the overall procedures outlined in the Median Cross-Over RSA
Guideline Report1 with some modifications given the characteristics of the facility being
reviewed. The process included identifying RSA team members; conducting field visits;
holding a RSA team meeting and then completing an assessment of the data and
findings from the field visits and meetings to render recommended actions for
MassHighway to consider. Data including recent traffic volume data, summary crash
records for the 2004-2007 period, detailed crash reports of cross-over crashes, and
available record highway plans were obtained and reviewed by the RSA consultant.
Field visits were conducted by the RSA team members. A video recording of the
sections under study was taken by the RSA Consultant. The site visits were completed
prior to the RSA team meeting that was held on August 28, 2008 at the MassHighway
District 4 offices. At that meeting, the RSA consultant provided a brief overview of the
RSA purpose, a summary of the roadway section’s characteristics and results of the
review to date. The RSA team provided input and discussed the key items noted in the
field and that were listed on the RSA Median Cross-Over Prompt List. Issues and
concerns were noted. Following the RSA meeting, the RSA consultant compiled the
information, completed the analysis and circulated the draft report.
•
RSA Team
The following were members of the I-495 Chelmsford Road Safety Audit:
Alex Normandin, MassHighway
Justin Howard, NMCOG
James Alexander, MassHighway, Projects
Misrak Sultan, MassHighway, Projects
Brett Loosian, MassHighway, District 4 Maint.
William J. Scully, MS Transportation systems
(RSA Consultant)
•
Erica Grygorcewicz, MassHighway
David Tilton, NMCOG
Lisa Schletzbaum, MassHighway, Safety
John Gregg, MassHighway, Traffic
James Bailey, Mass State Police, Concord
RSA Team Meeting
The RSA team meeting took place on August 28, 2008 at the District 4 offices in
Arlington. The team included engineers, planners and a representative from the State
Police barrack that has jurisdiction of I-495 in Chelmsford. Represented were
MassHighway (Boston and District), staff for Northern Middlesex Council of
Governments, as well as the State Police. A list of the team members contact
1
MS Transportation Systems, Inc., Road Safety Audits, Median Cross-Over Crashes, Audit Guidelines,
Prepared for MassHighway, October 2007.
MS Transportation Systems, Inc.
Page 3
I-495 Chelmsford Road Safety Audit
information are included in the Appendix. As stated previously, overall characteristics
and conditions of the study section were presented. The drive-through video and
photographs were reviewed and a discussion of the potential safety opportunities for
enhancement followed. Highlights of the discussion include the following:
•
The areas approximately 1,500 feet south of the rest areas are a concern of
the State Police due to the medians being more open and potentially
crossable – in these areas lane changing occurs as the parking area
entrance is in the NB direction and exiting the parking area in the SB
direction.
•
There is a sense that median related crashes may be under reported – not
likely so with respect to cross-median crashes.
•
Excessive travel speeds are not generally the problem, however, high truck
volume exists with a combination of lane changing and distractions appear to
influence crash activity.
•
Truck parking demand in the rest areas tend to exceed the supply and this
has led to more trucks parking just off the shoulder of the main line – most
noticeable in northbound direction.
It was also mentioned that it is a relatively dark stretch of road and at times fog near the
median. There is limited guidance or information in delineating the median location for
motorists and combined with fog can pose a higher risk to motorists related to median
entries.
•
Analysis Procedures
As previously indicated, the RSA analysis generally followed the procedure described in
the previously referenced Guideline with some variations and also took into
consideration the methods published by the Federal Highway Administration2 and those
included in training materials3. The basic tasks included:
•
•
2
3
Obtaining and reviewing crash and other traffic characteristic data and
available record plans.
Conducting site reconnaissance and collecting a current record of condition
via photos and video,
Federal Highway Administration, FHWA Road Safety Audit Guidelines, Publication No. FHWA SA-06-06,
Washington, D.C., 2006.
Federal Highway Administration, Resource Center, Road Safety Audits Mini-Workshop, Jeffrey Shaw, PE,
PTOE, presented to New England ITE Section, September 19, 2006.
MS Transportation Systems, Inc.
Page 4
I-495 Chelmsford Road Safety Audit
•
•
Identifying opportunities for enhancement, and
Identifying and evaluating potential actions to address the noted issues.
In assessing the issues identified by the RSA Team, the relative seriousness and
potential risk relative to crash frequency and severity were determined. Using the
guidelines of FHWA as input and considering characteristics of this specific RSA, the
relative frequency criteria and severity criteria were identified and are presented in Table
1 and Table 2, respectively.
ESTIMATED
Exposure
high
medium
high
medium
low
high
Probability
high
high
medium
medium
high
low
low
medium
low
medium
low
low
TABLE 1
FREQUENCY RATING
EXPECTED CRASH FREQUENCY
(PER AUDIT ITEM)
5 or more crashes per year
FREQUENCY
RATING
Frequent
1 to 4 crashes per year
Occasional
Less that 1 crash per year, but more
than 1 crash every 5 years
Infrequent
Less than 1 crash every 5 years
Rare
Source: FHWA RSA Training Workshop
Typical Crashes Expected
(per audit item)
High-speed crashes; head on and
rollover crashes
Moderate-speed crashes; fixed
object or off-road crashes
Crashes involving medium to low
speeds; lane changing or
sideswipe crashes
Crashes involving low to medium
speeds; typical of rear-end or
sideswipe crashes
TABLE 2
SEVERITY RATING
Expected Crash Severity
Probable fatality or
incapacitating injury
Moderate to severe injury
Severity
Rating
Extreme
High
Minor to moderate injury
Moderate
Property damage only or minor
injury
Low
Source: FHWA RSA Training Workshop
Taking into consideration both frequency and severity, the relative risk of a particular
audit item was rated. The risk ratings are shown in Table 3. For each safety issue
identified, the potential seriousness of the issue as well as possible mitigation measures
have been indicated.
MS Transportation Systems, Inc.
Page 5
I-495 Chelmsford Road Safety Audit
TABLE 3
CRASH RISK ASSESSMENT
Frequency
Rating
Frequent
Occasional
Infrequent
Rare
Severity Rating
Low
Moderate
High
Extreme
C
B
A
A
D
C
B
A
E
D
C
B
F
E
D
C
Source: FHWA RSA Training Workshop
Crash Risk Ratings:
A: minimal risk level
B: low risk level
C: moderate risk level
•
D: significant risk level
E: high risk level
F: extreme risk level
RSA Field Audit
Field audits were conducted by the RSA team members between on or before August
28, 2008. In general, the field visits included “drive-throughs” in each direction of the
study section noting physical conditions and the “feel” of the driver. The Prompt List
developed as part of the RSA process was used as a guide. The prompt list is included
in the appendix for background information. The RSA field audits took place by team
members prior to the RSA team meeting and revealed the following:
ƒ
There are three travel lanes per direction.
ƒ
Portions of the median are open while some portions, in particular, the
northern area of the study section, had guardrail and/or thick vegetation.
ƒ
Posted speeds were noted at 65 mph.
ƒ
The alignment of the roadway section under study is essentially straight.
ƒ
Inside rumble strips were not consistently incorporated into the shoulder –
possibly due to the narrow width of the inside shoulder in certain areas.
ƒ
The inside shoulder ranges from 1 to 3 feet which is less than a minimum
desired width of 4 feet.
ƒ
No delineation of the median via markers or flexible reflector posts were
in place.
ƒ
The entrance ramps from parking areas are not clearly indicated to
oncoming motorists.
ƒ
There was a feeling that the cross-slope on the inside travel lane was
steeper than expected giving the driver a sense of “falling off” the road –
this was most noticeable in the southbound direction.
MS Transportation Systems, Inc.
Page 6
I-495 Chelmsford Road Safety Audit
ANALYSIS
In completing the RSA of I-495 in Chelmsford, findings were compiled from the field
audits, the review of the data, and input provided by team members. The following
paragraphs summarize the results from each of the key components of the assessment.
The section of I-495 under study is approximately 4.2 miles in length with three (3) lanes
per direction separated by a median. The section includes three interchanges: No. 32 at
Boston Road, No. 33 at Route 4 and No. 34 at Route 110. There is less than one mile
separation between the Route 4 and Route 110 interchange.
The I-495 alignment in the project area is largely straight and level. Speeds are posted
at 65 miles per hour. The section of highway in the study area for the most part, has an
inside shoulder of approximately 1-3 feet in width. A rumble strip exists in some areas
and is missing in others. Recessed reflectors were not in place at the time of this
analysis. There was also a noticeable edge drop-off on a number of locations along the
study section as well. In addition, this section of I-495 does not have the reflective
delineator posts installed alongside the median. The low level of guidance was cited as
a potential contributing factor to median related entries particularly during times of low
visibility. One RSA team member noted fog as an issue and without some delineation,
the chances for median entries is increased.
Figure 2 – View of the median in the southbound direction.
The width of the median (measured from presumed edge line to edge line) in the project
area was between 95 and 110 feet. In total, 1.1 miles of the median is considered
“open” not including stretches of trees. There are rest areas located in both directions
MS Transportation Systems, Inc.
Page 7
I-495 Chelmsford Road Safety Audit
just south of Interchange No. 33 (Route 4). Observations by various team members
indicate the rest areas are well used. It was noted that truck parking demand often
exceeds capacity resulting in trucks parking along the shoulder north of the rest area.
Additionally, the acceleration lanes from the rest areas are short.
Figure 3 - Tangent section in northbound direction
approaching rest area.
Based on the recent MassHighway traffic counts north of Route 4, the roadway section
carries an average of 109,000 vehicles per day in the study section. Figure 6 illustrates
the directional volume over the course of the day for the sections, as can be seen in the
diagram. While there are two distinct peak hours (AM and PM commuter periods), there
is little difference in volumes by direction. Peak hour volumes are between 8,200 and
9,500 vehicles. The peak direction is experiencing in the range of 4,600 vehicles during
the peak hour. Truck volume on this section of I-495 is relatively high with 13% trucks
over the course of the day. This equates to more than 13,000 trucks.
Figure 4 – Entrance to NB rest area
MS Transportation Systems, Inc.
Figure 5 – NB exit from rest area
Page 8
I-495 Chelmsford Road Safety Audit
Figure 6 - I-495 Hourly Traffic Volumes North of Route 4
Data available as part of the MassHighway crash records system indicated that between
2004 and 2007, there were 48 reported crashes related to the median. Of the 48, only
one crash (2%) was identified as a cross-median crash. The one cross-median crash
resulted in a personal injury. A fatal crash did occur in early 2008 in the northern section
of the study section but where guardrail exists at the northern fringe of the study section.
That crash involved a trailer truck.
In most crashes, the cited driver contributing cause for the crash was non-reported.
Reasons cited were either driving too fast or failing to stay in proper lane. Weather
could have been a contributing factor in sixteen (33%) crashes with wet road surface.
Approximately half of the crashes resulted in property damage only. Conversely, nearly
half the median related crashes resulted in injury.
MS Transportation Systems, Inc.
Page 9
I-495 Chelmsford Road Safety Audit
SUMMARY OF RSA FINDINGS/POTENTIAL ACTIONS
Based on the field review, the review of crash data and discussions among the RSA
team members, the issues related to the safe operating conditions of the I-495 in the
Chelmsford area were identified. In essence, the RSA team determined that only a few
factors or issues of concern exist at this time that potentially have an effect on the risk.
These factors which also consider the crash type (i.e. cross-over median related), are
listed in Table 4 along with the assigned risk rating.
TABLE 4
SUMMARY OF FACTORS THAT POTENTIALLY AFFECT
THE RISK OF SAFETY RELATED EVENTS
Factor or Issue
Risk Rating
Open median
D
Inside paved shoulder width narrow and not consistent
E1
Rumble strips not in whole section along inside shoulder
E1
Median is not delineated with markers
D
Some recessed markers were missing – most noticed south
of Route 3
C
Unauthorized truck parking on shoulder north of NB rest area
B
Visibility of rest area exiting affected by profile approaching
the rest areas
B
Acceleration lanes from the rest areas appear short –
particularly NB direction
C
Cross-slope in high speed lane seems “steep” – particularly
in SB direction – gives some level of driver discomfort
D
Accel-decel lanes at interchanges appear short
C
High Travel speeds
C
Level of truck traffic and the effect on passenger driving
behavior
C
1 High risk level related to median entries not solely cross-overs
Although the section of I-495 under study experienced significantly high traffic volumes
(>100,000 ADT), the RSA team felt the drive through the section was generally a
“comfortable” drive without any substantive difficulties due to the overall geometry.
While there is a substantial length of open median (approx. 1.1 miles), it is approximately
100 feet in width and as evident by the low percentage (2%) of cross-over crashes,
appears to be generally sufficient in “retaining” errant motorists that enter the median.
MS Transportation Systems, Inc.
Page 10
I-495 Chelmsford Road Safety Audit
Thus, the open median in this section with the infrequent occurrence of a cross-median
crash but the likelihood of a fatality or incapacitating injury crash if the cross-median
crash occurs, a relatively low level risk rating of (D) was assigned although there does
appear to be a high risk factor pertaining to “median entries” themselves.
The RSA team identified several factors that pose potentially high risks, more related to
median entries and not necessarily cross-over crashes. These include the narrowness
of the inside shoulder (‘E’ Rating), an inconsistent application of the rumble strip (‘E’
Rating), and the median not being well delineated (‘D’ Rating). It was also noted that
there are some recessed lane line markers missing (‘C’ Rating). Another factor with a
relatively high risk rating (‘D’) assigned was the perception of the cross-slope of the
inside lane adjacent to the median particularly in the southbound direction.
The remaining factors such as the rest area parking condition, the acceleration lanes
from the rest areas and the level of truck traffic are anticipated to have less of an effect
than the above factors in contributing to median entries or cross-over crashes.
However, it is recognized that each of these factors can create additional or “quick” lane
changing which can lead to a median related event. These other factors were assigned
risk ratings of ‘B’ or ‘C’ as shown in Table 4. The awareness of the parking areas to
oncoming motorists is somewhat less than ideal. This affects not only the potential entry
into the parking areas but also the reminder that there is exiting from the parking areas.
This factor was assigned a rating of ‘B’.
There was also the issue of truck parking that occurs off the outside shoulder particularly
in the northbound direction. Based on discussions at the RSA meeting, this is largely
due to insufficient parking supply at the rest area. While the parked trucks can affect the
driver behavior, they are typically beyond part of the outside shoulder. A risk rating of ‘B’
was assigned to this factor.
The final two areas relates to markings and guidance through the acceleration and
deceleration lanes as well as indicating the location of the median. In general, there is a
low level of markings provided resulting in a sense of inadequate lanes, particularly
acceleration lanes. A reason for this low level treatment may be due to inadequately
wide shoulders carried through the interchange. This could be checked in detail prior to
future implementation or maintenance actions. The I-495 Corridor Study4 suggests all of
the acceleration and deceleration lanes can be increased through modifying the
markings.
4
FST, Inc., I-495 Corridor Transportation Study from Westford to Salisbury, Prepared for EOTPW, June,
2008.
MS Transportation Systems, Inc.
Page 11
I-495 Chelmsford Road Safety Audit
Finally, the travel speeds (generally higher than posted) and the high level of truck traffic
on I-495 creates a noticeable level of driver discomfort that can also affect lane changing
behavior. A risk rating of ‘C’ was assigned to these factors.
Suggested actions identified are intended to reduce the number of and consequences
resulting from median related crashes and other types of crashes as well. Given that the
primary objective of this program focuses on cross-median crashes, the initial action
evaluated was the possible installation of a median barrier. All recommended actions
intended to enhance safety in the study section are presented in the subsequent report
section.
•
Consideration of a Median Barrier
One of the more significant actions that could be considered is to install median barriers
in the current “open” areas. Although the RSA team concluded that the open median
section did not pose a high risk at this time, the section was evaluated in terms of the
median barrier warrants. A barrier can be considered when there is a higher than
desirable chance or a greater risk for median cross-over crashes to occur and that have
or could result in fatalities and/or a high proportion of injury related crashes. In addition,
a barrier could be considered when the consequences or severity of a crash without a
barrier are worse than if the barrier were in place.
Factors that generally come into play in deciding on whether a median should be
installed involve the following:
 High volumes and speeds
 Truck volumes and mix
 Narrow median
 History of cross-median crashes
 High risk of catastrophic event
These items have been reviewed relative to the I-495 section under study. Figure 7
presents a review of the corridor in relation to the median warrant criteria presented in the
AASHTO RDG5. As can be seen in the diagram, with the median (as measured from edge
line to edge line) is approximately 95-110 feet and a volume of over 100,000 vehicles on
an average day, the intersection of the two items to the right of the chart area where a
barrier can be “optional”. With the median approximately 100 feet in width, the point of
intersection is off the chart.
5
American Association of State Highway and Transportation Officials, Roadside Design Guide, Washington,
D.C., 2002, Chapter 6 Update 2006.
MS Transportation Systems, Inc.
Page 12
median width
95-110 feet
ADT - 109,000
80
AVERAGE DAILY TRAFFIC
(thousands)
70
BARRIER
RECOMMENDED
60
BARRIER
CONSIDERED
50
40
BARRIER
OPTIONAL
30
20
10
0
0
10
20
30
40
50
60
70
MEDIAN WIDTH
(feet)
Median Barrier Warrant Analysis
Interstate-495 Road Safety Audit
Chelmsford, Massachusetts
MS Transportation Systems, Inc.
NOT TO SCALE
Framingham, Massachusetts
Figure 7
I-495 Chelmsford Road Safety Audit
In addition to the analyzed AASHTO warrant criteria, which is a guideline, further
consideration was given to the following:
ƒ
ƒ
A small proportion (one of 48) of the median entries were cross-median
crashes over the four (4) year crash period was experienced.
The road geometry results in generally a comfortable drive.
Consequently, based on the analysis of the data, the field audit and drive-thru and
discussion of the conditions by the RSA team members, it was concluded that a median
barrier is not warranted on this section of I-495 at this time but could be considered if a
significant cross-median crash history develops. As will be discussed in the next section,
however, there are a number of other actions recommended as part of this RSA.
MS Transportation Systems, Inc.
Page 14
I-495 Chelmsford Road Safety Audit
Recommendations
As a result of the RSA analysis and team input and although it was concluded that a
median barrier not be installed at this time, a set of recommendations have been identified
and are summarized in Table 7. These actions are intended to eliminate the chance of
cross-median crashes as well as reduce the number and severity of all crashes of this
section of I-495 in Chelmsford. Identified in the table in addition to the risk factor and
recommended action are the estimated costs and potential timeframe (i.e. short (0-1 year),
medium (1-3 years) and long (>3 years)).
Although it was decided that a median barrier is not needed at this time within section and
can be considered a low priority action, it was recommended that improved delineation of
the median be implemented via reflectorized, flexible posts. In addition, it was
recommended that the inside shoulder be set wide enough to effectively accommodate a
rumble strip. Ideally, the inside shoulder would be a minimum of four (4) feet in width as
consistent with MassHighway and AASHTO design standards. The widening is proposed
as a long term item given its cost. It could be a lower cost if done in conjunction with
complete rehabilitation or resurfacing project. Consistent application of the rumble strip is
also needed. Although a low cost item, it would most likely be done with the shoulder
widening.
Another item that is recommended to be addressed when the section comes under
reconstruction is the cross-slope that was noted to be “steeper”, particularly in the
southbound direction. In addition, it was noted by the RSA team that a number of lane line
reflective markers were missing. New markers should be installed where missing, if
possible. It has been noted that since the markers were originally installed, MassHighway
now uses recessed markers. The replacement, consequently, may need to wait until a
new resurfacing project.
There are several actions related to the rest/parking areas including additional signage
(merge warning, YIELD) in the short term and additional NO PARKING signs north of the
rest area. In the longer term, the feasibility of providing an increase in parking capacity at
the rest area should be determined. Expanding the capacity may involve additional
property acquisition and require environmental permitting.
MS Transportation Systems, Inc.
Page 15
I-495 Chelmsford Road Safety Audit
TABLE 7
SUMMARY OF RECOMMENDATIONS
Risk Factor
Risk
Rating
Recommended
Action
Open median
D
ƒ
Inside paved shoulder width
narrow and not consistent
E
ƒ
Rumble strips not in whole
section along inside shoulder
E
ƒ
Median is not delineated with
markers
D
Some recessed markers were
missing – most noticed south of
Route 3
C
Unauthorized truck parking on
shoulder north of NB rest area
B
Visibility of rest area exiting
affected by profile approaching
the rest areas
B
Acceleration lanes from the rest
areas appear short –
particularly NB direction
C
Barrier NOT recommended
at this time
Widen paved shoulder to a
minimum of 4 feet
Estimated
Cost
Estimated Timeframe
N/A
N/A
$2M
ƒ
long term
Install new rumble strips
consistently in section
$12,000
ƒ
long term with
shoulder widening
ƒ
Install flexible, reflective
delineator posts
$7,000
ƒ
Short to medium
term
ƒ
Replace markers where
missing
TBD
ƒ
Short term
ƒ
ƒ
Add signage
Investigate feasibility of
providing more parking
$1,500
TBD
ƒ
ƒ
short term
medium term
ƒ
Add warning signs
(W4-1)
$2,000
ƒ
short term
ƒ
Verify condition, modify
markings if applicable
Add YIELD signs for exit
ramps
$2,000
ƒ
short term
$500
ƒ
short term
TBD
ƒ
long term
TBD
$1,500
ƒ
ƒ
short term
short term
ƒ
ƒ
Verify slope – correct in
future rehabilitation project
C
ƒ
ƒ
Modify markings
Install YIELD signs if
necessary
High travel speeds
C
ƒ
Increased enforcement
TBD
ƒ
short term
Level of truck traffic and the
effect on passenger car driving
behavior
C
ƒ
Post driver information
signage possibly with
temporary VMS units
TBD
ƒ
Short to medium
term
Cross-slope in high speed lane
seems “steep” – particularly in
SB direction – gives some level
of driver discomfort
D
Accel-decel lanes at
interchanges appear short
TBD – to be determined
It is suggested that improved markings be provided for the acceleration and deceleration
lanes including the gore areas. This could be accomplished through a combination of
markings and signage. Consistent, high visibility markings using dotted lines such as
those shown in Figure 8 should be considered. The current MUTCD depicts options with
dotted lines for deceleration lanes and weave sections. The upcoming revised MUTCD is
expected to include dotted lines for acceleration lanes as well. The outside shoulder width
may be an issue regarding lengthening the lane lines.
MS Transportation Systems, Inc.
Page 16
a-Parallel
deceleration lane
b-Tapered
deceleration lane
Neutral
area
Optional
chevron
markings
Channelizin
g lines
Theoretical gore
point
Channelizing
lines
Broken lane
markings for
one-half of
full-width
deceleration
lane
Optional
dotted
extension
of lane
line
Legend
Direction of
travel
Source: Based on MUTCD Figure 3B-8
Note: Conceptual illustration only
Potential Pavement Markings Off-Ramp Deceleration Lanes
I-495 Road Safety Audit
Chelmsford, Massachusetts
MS Transportation Systems, Inc.
NOT TO SCALE
Framingham, Massachusetts
FIGURE 8
I-495 Chelmsford Road Safety Audit
The previously noted I-495 study noted that most acceleration-deceleration lanes were
deficient and could be corrected by modifying the markings only. This can be examined in
more detail when scheduling pavement marking maintenance activities in the future.
Travel speeds and driver behavior has been cited and observed to be a problem on I-495
where volumes are in the range of 110,000 ADT. Increased enforcement presence is
essential in addressing this behavior. This will require additional funding.
The high volume of truck traffic also affects driver comfort levels and lane changing
behavior. This section of I-495 is a major trucking route and the volume is not expected to
reduce. A passive action discussed was the use of VMS signage as a way to encourage
more positive driver behaviors such as caution, courtesy, etc. The VMS package could
also be used to inform motorists of congestion and downstream delays as a way to also
encourage some patience and better drive decision.
MS Transportation Systems, Inc.
Page 18
I-495 Chelmsford Road Safety Audit
Appendix
•
•
•
•
•
MS Transportation Systems, Inc.
RSA Meeting Agenda
RSA Attendees List
Median Crash Diagram
Crash Data
Traffic Volume Data
Page 19
Road Safety Audit
Chelmsford – Interstate 495
Meeting Location: MassHighway District 4 Office
519 Appleton Street, Arlington
Thursday, August 28, 2008
11:00 AM – 12:30 PM
Type of meeting:
Cross Median – Road Safety Audit
Attendees:
Invited Participants to Comprise a Multidisciplinary Team
Please bring:
Thoughts and Enthusiasm!!
11:00 AM
Welcome and Introductions
11:15 AM
Introduction to Road Safety Audits and Cross Median Crashes
11:30 AM
Review of Site Specific Material
• Crash & Volume Summaries– provided in advance
• Existing Geometries and Conditions
• Video and Images
12:00 PM
Completion of RSA
• Identification of Safety Concerns – using RSA Prompt List as a guide
• Identification of Possible Countermeasures
12:30 PM
Adjourn for Lunch – but the RSA has not ended
Instructions for Participants:
• Before attending the RSA on August 28th participants are encouraged to drive
Interstate 495 near interchange 33 and complete/consider elements on the RSA
Prompt List with a focus on safety factors affecting cross median crashes.
• All participants will be actively involved in the process throughout. Participants
are encouraged to come with thoughts and ideas, but are reminded that the
synergy that develops and respect for others’ opinions are key elements to the
success of the overall RSA process.
• After the initial RSA meeting, participants will be asked to comment and respond
to the document materials to assure it is reflective of the RSA completed by the
multidisciplinary team.
ROAD SAFETY AUDIT MEETING
I-495 Chelmsford August 28, 2008
MassHighway District 4 Offices, Arlington MA
Attendance List
Name
Agency/Dept.
Email
Bill Scully
MS Transportation Systems, Inc.
bscullyjr@mac.com
Lisa Schletzbaum
MHD Safety Management Unit
Lisa.Schletzbaum@mhd.state.ma.us
Alex Normandin
MHD
Alex.Normandin@mhd.state.ma.us
Erica Grygorcewicz
MHD
Erica.Grygorcewicz@mhd.state.ma.us
Justin Howard
NMCOG
Jhoward@nmcog.org
David Tilton
NMCOG
Dtilton@nmcog.org
James Alexander
MHD Projects
Jim.Alexander@mhd.state.ma.us
Misrak Sultan
MHD Projects
Sultan.M@mhd.state.ma.us
John Gregg
MHD Traffic
John.Gregg@mhd.state.ma.us
Brett Loosian
MHD, District 4, Maintenance
Brett.Loosian@mhd.state.ma.us
James Baily
MDP Concord
James.Baily@pol.state.ma.us
MS Transportation Systems, Inc.
±
O
ST
BO
Interstate 495 Median Crashes
N
RO
EET
S TR
TH
AD
Crash IDs
between 11 - 20
36
33
21
10
EC
RN
E
V
RI
KR
O
AD
AM
S
IC
A
R
O
KE
N
U
AD
PI
E
RN
AV
R
TU
T
LE
IT T
AD
LE
BR ICK
K ILN R
6
AD
RO
ON
BI
L
OA D
CHELMSFORD
7
L
32
D
3
4
9
35 37
34
R OA
N CO V E
GOL D E
8
5
"
)
33
36
35
34
E
R
T
RE
E
ST
ET
T
Type of Median Crash 2004 - 2007 * Major Roads
BA
RT
L
§
¦
¨
495
AD
Legend
O
2
1
38
"
)
"
)
"
)
E ET
CA R
L
N
DMA
R
NO
Crash IDs
between 22 - 31
E ET
RD ST R
WE S T FO
T
S TR
PA
RK
H
E
ST R E
SWA N
IS L E
UR
ST
RO
AD
£
¤
D
OA
NR
LD
E
LOWELL
3
STO
BO
O
W
AD
RO
ITE
D
OA
ER
RO
A
ST E
AN
GR
L
V IL
FO
ST
RD
AD
Cross-Median, Non Fatal Crash
Interstate
Median, Non Fatal Crash
Principal Arterial
Municipal Boundary
Minor Arterial
Collector
CON CORD ROAD
Local
M IL
* 2007 crash
L
BO R OA D
ST
O
N 0
0.2
RO
AD
file has not yet been closed.
0.4
0.6
Miles
0.8
MASSHIGHWAY SAFETY DIVISION
CRASH SUMMARY
ROADWAY:
STUDY PERIOD:
I-495
1/1/2004
NO.
CRASH NUMBER
CRASH DATE
1
2
3
4
2083033
5/13/2006
12/29/2007
11/4/2007
6/28/2007
TO
TRAVEL
DIRECTION
NB
NB
SB
NB
5
6
7
8
9
2114992
8/8/2006
5/25/2007
6/5/2005
8/10/2007
5/3/2005
SB
NB
NB
NB
NB
Daylight
Daylight
Dark - Not Lighted
Daylight
Dark- Lighted
Clear
Clear
Cloudy
Rain
Clear
Dry
Dry
Dry
Wet
Dry
REASON FOR
VEHICLE
RUNNING OFF ROAD LEFT
MOVEMENT
Lost control of vehicle, hit median guardrail, struck two vehicles, came to rest in median
Travel Lane to Median Guardrail to Travel Lane to Median
Vehicle was cut-off by unknown vehicle
Travel Lane to Median
Vehicle drifted left onto median, turned right sharply, crossed lanes past right shoulder, and overturned
Travel Lane to Median to Right Shoulder
Vehicle tire blew out, lost control of vehicle, struck another vehicle, and both ran off road to left
Travel Lane to Median
Lost control due to stopped traffic, two vehicles collided, one vehicle hit trees in median, one vehicle stopped
on grass
Travel Lane to Trees in the Median
Lost control of vehicle, ran off road to left, and hit highway sign
Travel Lane to Median
Fallen asleep, vehicle drifted left onto median, and overturned
Travel Lane to Median
Lost control of vehicle, struck another vehicle, and drifted left onto median
Travel Lane to Median
Lost control of vehicle, rolled several times, hit trees in median
Travel Lane to Trees in the Median
10
11
12
13
14
15
2050469
4/15/2006
9/11/2007
8/16/2007
7/13/2007
6/30/2007
1/27/2005
NB
NB
NB
NB
NB
NB
Daylight
Daylight
Dark- Lighted
Dark- Lighted
Daylight
Daylight
Cloudy
Rain
Clear
Clear
Clear
Clear
Dry
Wet
Dry
Dry
Dry
Dry
Ran off road to left, struck trees
Vehicle hydroplaned, hit median guardrail, and struck another vehicle
Vehicle was cut-off by unknown vehicle, lost control of vehicle, and hit median guardrail
Vehicle drifted to the left, hit median guardrail
Lost control of vehicle, hit median guardrail, and struck another vehicle
Vehicle cut-off by another vehicle, hit median guardrail
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
1796190
2136814
4/11/2004
12/16/2007
10/1/2007
10/6/2005
5/25/2005
12/16/2005
1/14/2006
1/13/2007
8/8/2005
9/2/2007
8/19/2007
4/4/2007
8/1/2006
3/1/2005
12/18/2007
9/19/2007
7/27/2006
3/2/2006
1/23/2006
11/24/2005
5/26/2004
3/2/2007
8/8/2007
9/20/2004
2/28/2005
9/23/2005
10/5/2005
6/1/2006
9/23/2006
12/5/2006
4/12/2006
SB
NB
NB
NB
SB
SB
SB
SB
NB
NB
NB
NB
SB
SB
SB
SB
SB
NB
NB
SB
NB
SB
SB
SB
SB
NB
NB
SB
NB
NB
NB
Dark - Not Lighted
Dark
Dark - Not Lighted
Daylight
Dark - Not Lighted
Daylight
Dark- Lighted
Daylight
Daylight
Daylight
Daylight
Dark - Not Lighted
Dark- Lighted
Daylight
Daylight
Daylight
Dark- Lighted
Daylight
Dark- Lighted
Daylight
Daylight
Dark- Lighted
Daylight
Daylight
Dawn
Daylight
Dark - Not Lighted
Daylight
Dark - Not Lighted
Daylight
Daylight
Clear
Sleet
Clear
Clear
Rain
Sleet
Cloudy
Rain
Clear
Clear
Clear
Snow
Clear
Snow
Clear
Clear
Clear
Clear
Sleet
Snow
Rain
Sleet
Clear
Cloudy
Clear
Clear
Clear
Clear
Clear
Clear
Clear
Dry
Ice
Dry
Dry
Wet
Ice
Dry
Wet
Dry
Dry
Dry
Snow
Dry
Slush
Wet
Dry
Dry
Dry
Wet
Snow
Wet
Ice
Wet
Dry
Dry
Dry
Dry
Dry
Dry
Dry
Dry
47
48
2179487
2256834
4/19/2007
10/19/2007
NB
NB
Not Reported
Dark - Not Lighted
Not Reported
Rain
Not Reported
Wet
2318882
2256552
2221999
2211701
2001258
2225869
2001180
2234785
2229137
2238086
2229124
1916153
2266283
2236234
2002284
1916308
2002871
2014891
2148394
2001438
2235522
2228526
2254358
2114965
1916214
2264796
2230089
2114945
2050382
2014824
2049855
1898991
2176757
2225568
1834508
2001017
2002167
2002251
2114732
2115306
2130296
TOTAL NO.
48
100%
DAYLIGHT
27
56%
DAWN
2
4%
12/31/2007
LIGHT
CONDITION
Dawn
Dark - Not Lighted
Daylight
Daylight
Rain
Not Reported
Clear
Clear
Wet
Dry
Dry
Dry
LIGHT CONDITION
DARK - NOT
LIGHTED
DARK - LIGHTED
10
8
21%
17%
WEATHER
CONDITION
ROAD
SURFACE
WET
ICE
31
65%
10
21%
3
6%
NO
IMPROPER
DRIVING
7
15%
EXCEEDED
AUTHORIZED
SPEED LIMIT
3
6%
SNOW
NOT REPORTED
1
2%
CLEAR
28
58%
CLOUDY
4
8%
RAIN
7
15%
MEDIAN OR CROSS MEDIAN
SLUSH
CHELMSFORD
EXIT 33
DRIVER CONTRIBUTING
CAUSE
Driving too fast for conditions, Failure to keep in proper lane or running off road
Alcohol
Not reported
Not reported
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Followed too closely, Failure to keep in proper lane or running off road
Property Damage Only
Not reported
Property Damage Only
Failure to keep in proper lane or running off road, Fatigued/asleep
Property Damage Only
Not reported
Non-Fatal Injury
Alcohol, Exceeded authorized speed limit, Physical impairment
Non-Fatal Injury
Exceeded authorized speed limit, Operating vehicle in erratic, reckless, careless, negligent o
aggressive manner
Non-Fatal Injury
Not reported
Property Damage Only
Not reported
Property Damage Only
Alcohol
Property Damage Only
Not reported
Property Damage Only
No improper driving
Property Damage Only
Cross-Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Median
Fatigued/asleep
Not reported
Not reported
No improper driving
Driving too fast for conditions
No improper driving
Failure to keep in proper lane or running off road, Fatigued/asleep
Failure to keep in proper lane or running off road
Exceeded authorized speed limit, Failure to keep in proper lane or running off road
Not reported
Not reported
Not reported
Failure to keep in proper lane or running off road, Fatigued/asleep
No improper driving
Not reported
Not reported
Failure to keep in proper lane or running off road, Inattention
Inattention
No improper driving
No improper driving
Failure to keep in proper lane or running off road
Not reported
Not reported
Visibility obstructed
Failure to keep in proper lane or running off road, Distracted
Failure to keep in proper lane or running off road, Other improper action
Operating vehicle in erratic, reckless, careless, negligent or aggressive manner
Not reported
No improper driving
Over-correcting/over-steering
Not reported
Non-Fatal Injury
Non-Fatal Injury
Property Damage Only
Non-Fatal Injury
Non-Fatal Injury
Property Damage Only
Non-Fatal Injury
Property Damage Only
Property Damage Only
Non-Fatal Injury
Property Damage Only
Property Damage Only
Non-Fatal Injury
Property Damage Only
Property Damage Only
Non-Fatal Injury
Property Damage Only
Non-Fatal Injury
Property Damage Only
Property Damage Only
Property Damage Only
Non-Fatal Injury
Non-Fatal Injury
Property Damage Only
Property Damage Only
Property Damage Only
Non-Fatal Injury
Non-Fatal Injury
Non-Fatal Injury
Non-Fatal Injury
Property Damage Only
Median
Median
Not reported
Not reported
Not Reported
Property Damage Only
CRASH
SEVERITY
Non-Fatal Injury
Property Damage Only
Non-Fatal Injury
Property Damage Only
WEATHER CONDITION
ROAD SURFACE
DRY
Travel Lane to Trees in the Median
Travel Lane to Median Guardrail to Travel Lane
Travel Lane to Median Guardrail
Travel Lane to Median Guardrail
Travel Lane to Median Guardrail to Travel Lane
Travel Lane to Median Guardrail
S/B Travel Lane to Median to N/B Travel Lane to N/B Right
Fallen asleep, vehicle drifted left onto median, overturned onto N/B side, driven to N/B right breakdown laneBreakdown Lane
Lost control of vehicle, ran off road to left, and overturned
Travel Lane to Median
Vehicle drifted left onto median, lost control, crossed lanes onto right-hand off-ramp, and overturned
Travel Lane to Median to Off-ramp on Right
Vehicle cut-off by another vehicle, ran off road to left, lost control of vehicle, and struck trees
Travel Lane to Trees in the Median
Lost control of vehicle, drifted left onto median, struck trees, and turned onto driver's side
Travel Lane to Trees in the Median
Vehicle hydroplaned, struck another vehicle, and hit median guardrail
Travel Lane to Median Guardrail
Fallen asleep, lost control of vehicle, and hit median guardrail
Travel Lane to Median Guardrail
Vehicle cut-off by another vehicle, struck another vehicle, and hit median barrier
Travel Lane to Median Barrier
Vehicle cut-off by another vehicle, hit median guardrail, and overturned
Travel Lane to Median Guardrail
Lost control of vehicle, hit median barrier, cross to right breakdown lane, and overturned
Travel Lane to Median Barrier to Right Breakdown Lane
Fallen asleep, vehicle drifted left onto median, turned right sharply, and hit by another vehicle
Travel Lane to Median to Travel Lane
Vehicle struck by another vehicle, lost control of vehicle, ran off road to left
Travel Lane to Median
Fallen asleep, hit median guardrail
Travel Lane to Median Guardrail
Lost control of vehicle due to slush, hit median guardrail
Travel Lane to Median Guardrail
Lost control of vehicle, crashed into right guardrail, and bounced back into median guardrail
Travel Lane to Right Guardrail to Median Guardrail
Vehicle tire blew out, lost control of vehicle, hit median guardrail, and turned onto passenger side
Travel Lane to Median Guardrail
Lost control of vehicle, hit median guardrail
Travel Lane to Median Guardrail
Vehicle sideswiped by another vehicle, lost control of vehicle, hit median guardrail
Travel Lane to Median Guardrail
Vehicle cut-off by another vehicle, hit median guardrail, lost control of vehicle, and hit right guardrail
Travel Lane to Median Guardrail to Right Guardrail
Vehicle cut-off by another vehicle, hit median guardrail
Travel Lane to Median Guardrail
Vehicle sideswiped by other vehicle, hit median barrier
Travel Lane to Median Barrier
Lost control of vehicle, hit median barrier, and overturned
Travel Lane to Median Barrier
Vehicle sideswiped other vehicle, both spun out and hit median guardrail
Travel Lane to Median Guardrail
Vehicle cut-off by another vehicle avoiding construction barrels on right, hit median barrier
Travel Lane to Median Barrier
Lost control of vehicle due to plastic bag in roadway, hit median guardrail
Travel Lane to Median Guardrail
Swerved left due to stopped traffic, hit median guardrail
Travel Lane to Median Guardrail
Lost control of vehicle, drifted left onto median
Travel Lane to Median
Ran off road to left, lost control of vehicle, struck trees, and overturned
Travel Lane to Trees in the Median
Ran off road to left, struck trees
Travel Lane to Trees in the Median
Lost control of vehicle, ran off road to left, and overturned
Travel Lane to Median
Ran off road to left, hit median guardrail
Travel Lane to Median Guardrail
Vehicle sideswiped by other vehicle, lost control of vehicle, hit median guardrail, and came to rest in right
breakdown lane
Travel Lane to Median Barrier to Right Breakdown Lane
Lost control of vehicle, hit median guardrail, and came to rest in right breakdown lan
Travel Lane to Median Guardrail to the Right Breakdown Lane
CITY:
LOCATION:
MEDIAN OR CROSS
MEDIAN CRASHES
Median
Median
Median
Median
NOT REPORTED
2
1
1
4%
2%
2%
DRIVER CONTRIBUTING CAUSE
FAILURE TO KEEP
IN PROPER LANE
FOLLOWED
DRIVING TOO FAST
OR RUNNING OFF TOO CLOSELY FOR CONDITIONS FATIGUED/ASLEEP
11
1
2
4
23%
2%
4%
8%
SLEET
4
8%
NOT REPORTED
2
4%
DRIVER
CONTRIBUTING
CAUSE
NON-FATAL INJURY
NOT REPORTED
NOT REPORTED
20
42%
1
2%
20
42%
PHYSICAL
IMPAIRMENT/ALCOHOL
3
6%
VISIBILITY OBSTRUCTED
1
2%
OTHER IMPROPER
ACTION
1
2%
CRASH SEVERITY
MEDIAN
CROSS MEDIAN
47
98%
1
2%
PROPERTY DAMAGE
ONLY
28
58%
INATTENTION
2
4%
OPERATING VEHICLE IN ERRATIC, RECKLESS, CARELESS, NEGLIGENT, OR
AGGRESSIVE MANNER
2
4%
OVER-CORRECTING/OVER-STEERING
1
2%
2007 CRASH INFORMATION IS NOT COMPLETE
CRASH SUMMARY IS BASED ON CRASH REPORTS WITH STATE POLICE NARRATIVES
SNOW
3
6%
I-495, North of Route 4
Start Time Northbound
Southbound Total
12:00 AM
480
347
827
1:00 AM
328
230
558
2:00 AM
305
238
543
3:00 AM
309
256
565
4:00 AM
526
495
1021
5:00 AM
1306
1273
2579
6:00 AM
2997
3198
6195
7:00 AM
4058
4606
8664
8:00 AM
4577
3758
8335
9:00 AM
3273
3493
6766
10:00 AM
2431
2561
4992
11:00 AM
2480
2507
4987
12:00 PM
2467
2515
4982
1:00 PM
2764
2730
5494
2:00 PM
3093
3154
6247
3:00 PM
4186
3965
8151
4:00 PM
4404
4433
8837
5:00 PM
4534
4798
9332
6:00 PM
3572
3437
7009
7:00 PM
2058
2054
4112
8:00 PM
1536
1541
3077
9:00 PM
1215
1271
2486
10:00 PM
961
909
1870
11:00 PM
780
632
1412
Daily Total
54640
54401
109041
6000
5000
4000
Northbound
Southbound
3000
2000
1000
PM
PM
10
:0
0
8:
00
PM
6:
00
PM
PM
Time of Day
4:
00
PM
2:
00
AM
12
:0
0
AM
10
:0
0
AM
8:
00
AM
6:
00
4:
00
AM
2:
00
AM
0
12
:0
0
Hourly Volumes (Number of Vehicles)
Directional Traffic Volumes along I-495 Chelmsford
Thursday, April 26 2007