CTPS
CENTRAL TRANSPORTATION PLANNING STAFF
Staff to the Boston Region Metropolitan Planning Organization
DRAFT MEMORANDUM
To: Steve McLaughlin MassDOT
From: Ying Bao, Scott Peterson
Re: Air Quality Analyses for Casey Overpass Project
December 21, 2011
BACKGROUND
This memorandum summarized the results of the (CTPS) air quality analysis conducted for the
Casey Overpass study. The air quality analysis utilized the standard outputs from the regional travel forecasting model set developed and maintained by the Central Transportation Planning
Staff (CTPS). The results focused on the change of air pollutions to the neighborhoods near the
Casey Overpass for the different roadway projects in the AM and PM peak 3 hour travel periods.
METHODOLOGY
The air quality analysis described below is based on linking the regional travel demand model with emission factors produced by an emissions model. The analysis for this study utilized the same methodology used for regional air quality conformity determinations, which was recently certified by the Federal Transit Administration (FTA) and the Federal Highway Administration
(FHWA) for the Long Range Transportation Plan. The travel demand model set examines transportation flows by mode on the entire eastern Massachusetts highway and transit systems.
The travel demand model estimates traffic volumes, average highway speeds, vehicle-miles traveled and vehicle-hours traveled. In conjunction with the travel demand model, emission rates were developed using the Environmental Protection Agency’s (EPA) MOBILE 6.2 emissions modeling software. CTPS utilize these outputs to forecast emissions for the no-build condition
(existing condition), and the two build alternatives in 2035.
In general, the air quality analysis estimated emissions from cars and trucks of carbon monoxide
(CO), carbon dioxide (CO2), nitrogen oxides (NOx), volatile organic compounds (VOCs), and particulate matters (PM
2.5
and PM
10
). Emissions from the commuter rail diesel locomotives, transit service boats, and MBTA buses are estimated off model and were not included in this analysis due to the lack of changes to the transit operating plans in both build scenarios.
RESULTS SUMMARY
The Casey Overpass study focused on eight neighborhoods near Forest Hills for this study, as shown in Figure 1. These neighborhoods were Hyde Park, Jamaica Plain, Mattapan, north
Dorchester, Roslindale, Roxbury, South Dorchester, and West Roxbury. Since the emission
State Transportation Building
•
Ten Park Plaza, Suite 2150
•
Boston, MA 02116-3968
•
(617) 973-7100
•
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•
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•
ctps@ctps.org

Steve McLaughlin, MassDOT 2 December 21, 2011 factors and transit networks remained constant between the no-build and build alternatives, the changes shown are simply a result of the different levels of roadway congestions and route choice.
Table 1 through table 8 in the end of this memorandum summarized the results of air quality analysis during AM and PM peak periods for Casey Overpass study. In summary, these results showed that there was no significant changes on the vehicle-miles traveled (VMT), vehicle-hours traveled (VHT), and average speed in the selected neighborhoods near Forest Hills area. The changes of air pollutions between the existing conditions and both build alternatives were also minimal.
Table 1 and 2 presented the aggregated VMT and VHT in AM and PM peak periods for each neighborhood, respectively. The results in both tables were rounded to the nearest 50, to account for the accuracy level of the model and the highway assignment. Overall, the changes in the
CTPS model region and Casey study area in both build alternatives were insignificant compared to the no-build alternative. In the build alternatives, the aggregated VMT and VHT in Mattapan were reduced in both peak periods, which meant traffic in Mattapan traveled shorter distance and cost less time with the existing Casey Overpass being replaced. On the other hand, Roslindale had a small increase of VMT and VHT. However, the magnitudes of all changes by neighborhood (whether increase or reduce) were very small and on net showed no change relative to the no-build condition. Table 3 summarized the average speed of vehicle in congested condition in each neighborhood. The average speeds were calculated using the following equation:
Average speed = VMT / VHT
The results showed that the average speeds near the Casey Overpass study area were much slower than the speeds in the model region for all three future scenarios. In both of the build alternatives, speeds in the Jamaica Plain were reduced by approximately 5% in morning peak. In the evening peak, speeds in Roslindale were reduced by 4%.West Roxbury obtained the benefit from the roadway project in both alternatives with an average speed increase of 4% in the morning.
The summaries of carbon monoxide (CO) and carbon dioxide (CO2) emissions are presented in table 4 and 5, respectively. The results of carbon monoxide were rounded to the nearest 10 kilograms, and those of carbon dioxide were rounded to the nearest 100 kilograms, based on the confidence levels associated with the emissions modeling software for that pollutant. Both tables showed there was less than 0.5 percent increase of both air pollutions in the overall study area.
Roslindale, Roxbury and West Roxbury had more than one percent of increased of CO emissions. Jamaica Plain and Mattapan had the declined carbon dioxide emissions, while other neighborhood had slightly increased CO
2
emissions. No changes (whether positive or negative) in either build alternative was greater than one percent compared to the no-build alternative.
Table 6 listed the results of nitrogen oxides (NOx) calculated by the air quality analysis. It showed that Mattapan NOx emission reduced the by 10 percent in PM peak in both build alternatives. Table 7 and 8 were the summaries of volatile organic compounds (VOC), and fine

Steve McLaughlin, MassDOT 3 December 21, 2011 particulate matters (PM
2.5
). The VOC results were rounded to the nearest one kilogram, while those of PM2.5 were rounded to the nearest 100 grams to reflect the confidence level of results coming out of the travel demand model and the emissions model. No changes of these pollutions were found in either build alternatives compared to the no-build condition.
SAP/yb/yb
Figure 1: Neighborhood Boundaries

Neighborhood
Hyde Park
Jamaica Plain
Mattapan
North Dorchester
Roxbury
Roslindale
South Dorchester
West Roxbury
Study Area Total
Regional Total
Neighborhood
Hyde Park
Jamaica Plain
Mattapan
North Dorchester
Roxbury
Roslindale
South Dorchester
West Roxbury
Study Area Total
Regional Total
Table 1 Summary of Vehicle-Miles Traveled in Casey Overpass Study Area
No-Build
55,450
73,850
50,100
145,450
69,350
60,350
169,050
88,200
711,800 712,100
23,268,000 23,267,600
55,650
73,400
49,650
145,600
69,550
60,750
169,150
88,350
AM Peak Period (3-hour)
At-Grade
0.4%
-0.6%
-0.9%
0.1%
0.3%
0.7%
0.1%
0.2%
Bridge
55,600
73,400
49,650
145,550
69,500
60,650
169,050
88,550
0.0% 711,950
0.0% 23,268,100
VMT (miles)
No-Build
0.3%
-0.6%
-0.9%
0.1%
0.2%
0.5%
0.0%
0.4%
66,650
80,200
59,200
154,250
80,550
70,350
180,100
98,050
0.0% 789,350 789,850
0.0% 25,309,600 25,309,600
66,900
80,350
58,750
154,250
80,600
70,350
180,300
98,350
PM Peak Period (3-hour)
At-Grade
0.4%
0.2%
-0.8%
0.0%
0.1%
0.0%
0.1%
0.3%
Bridge
66,900
79,900
58,800
154,300
80,600
70,200
180,300
98,500
0.1% 789,500
0.0% 25,309,200
0.4%
-0.4%
-0.7%
0.0%
0.1%
-0.2%
0.1%
0.5%
0.0%
0.0%
Table 2 Summary of Vehicle-Hours Traveled in Casey Overpass Study Area
No-Build
2,200
3,950
2,350
7,200
4,100
2,450
7,750
3,350
33,350
709,300
AM Peak Period (3-hour)
4,100
2,500
7,750
3,300
33,300
709,300
At-Grade
2,200
3,950
2,300
7,200
0.0%
0.0%
-2.1%
0.0%
0.0%
2.0%
0.0%
-1.5%
-0.1%
0.0%
4,100
2,500
7,750
3,350
33,350
709,200
Bridge
2,200
3,950
2,300
7,200
VHT (hours)
0.0%
No-Build
2,750
0.0%
-2.1%
0.0%
4,400
2,800
6,950
0.0%
2.0%
0.0%
0.0%
0.0%
0.0%
4,650
2,950
8,500
3,800
36,800
774,600
PM Peak Period (3-hour)
4,650
3,000
8,550
3,800
36,850
774,700
At-Grade
2,750
4,400
2,750
6,950
0.0%
0.0%
-1.8%
0.0%
0.0%
1.7%
0.6%
0.0%
0.1%
0.0%
4,650
3,050
8,550
3,850
36,950
774,700
Bridge
2,750
4,400
2,750
6,950
0.0%
0.0%
-1.8%
0.0%
0.0%
3.4%
0.6%
1.3%
0.4%
0.0%

Neighborhood
Hyde Park
Jamaica Plain
Mattapan
North Dorchester
Roxbury
Roslindale
South Dorchester
West Roxbury
Study Area Average
Regional Average
Neighborhood
Hyde Park
Jamaica Plain
Mattapan
North Dorchester
Roxbury
Roslindale
South Dorchester
West Roxbury
Study Area Total
Regional Total
Table 3 Summary of Average Speed in Casey Overpass Study Area
No-Build
25
19
22
20
17
24
22
26
21
33
AM Peak Period (3-hour)
At-Grade
25
18
22
20
17
24
22
27
21
33
0.0%
-5.3%
0.0%
0.0%
0.0%
0.0%
0.0%
3.8%
0.0%
0.0%
Bridge
25
18
22
20
17
24
22
27
21
33
Average Speed (mph)
No-Build
0.0%
-5.3%
0.0%
0.0%
0.0%
0.0%
0.0%
3.8%
0.0%
0.0%
24
18
21
22
17
24
21
26
21
33
PM Peak Period (3-hour)
At-Grade
24
18
21
22
17
23
21
26
21
33
0.0%
0.0%
0.0%
0.0%
0.0%
-4.2%
0.0%
0.0%
0.0%
0.0%
Table 4 Summary of Carbon Monoxide (CO) in Casey Overpass Study Area
No-Build
460
630
420
1,240
590
500
1,410
720
5,970
194,900
AM Peak Period (3-hour)
600
510
1,410
730
6,000
194,900
At-Grade
460
630
420
1,240
0.0%
0.0%
0.0%
0.0%
1.7%
2.0%
0.0%
1.4%
0.5%
0.0%
600
500
1,410
730
5,990
194,900
Bridge
460
630
420
1,240
CO (kg)
0.0%
No-Build
560
0.0%
0.0%
0.0%
690
500
1,290
1.7%
0.0%
0.0%
1.4%
0.3%
0.0%
690
590
1,530
810
6,660
213,100
Bridge
24
18
21
22
17
23
21
26
21
33
0.0%
0.0%
0.0%
0.0%
0.0%
-4.2%
0.0%
0.0%
0.0%
0.0%
PM Peak Period (3-hour)
690
590
1,530
810
6,660
213,100
At-Grade
560
690
500
1,290
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
690
590
1,530
820
6,670
213,100
Bridge
560
690
500
1,290
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
1.2%
0.2%
0.0%

Neighborhood
Hyde Park
Jamaica Plain
Mattapan
North Dorchester
Roxbury
Roslindale
South Dorchester
West Roxbury
Study Area Total
Regional Total
Neighborhood
Hyde Park
Jamaica Plain
Mattapan
North Dorchester
Roxbury
Roslindale
South Dorchester
West Roxbury
Study Area Total
Regional Total
Table 5 Summary of Carbon Dioxide (CO2) in Casey Overpass Study Area
No-Build
30,500
40,600
27,600
79,000
37,800
33,300
92,300
48,600
AM Peak Period (3-hour)
At-Grade
30,600
40,400
27,400
79,100
37,900
33,600
92,300
48,700
389,700 390,000
12,639,500 12,639,300
0.3%
-0.5%
-0.7%
0.1%
0.3%
0.9%
0.0%
0.2%
0.1% 390,000
0.0% 12,639,600
Bridge
30,600
40,400
27,400
79,100
37,900
33,500
92,300
48,800
CO
2
(kg)
0.3%
No-Build
37,000
-0.5%
-0.7%
0.1%
44,400
32,900
84,600
0.3%
0.6%
0.0%
0.4%
44,300
39,100
99,100
54,500
PM Peak Period (3-hour)
At-Grade
37,100
44,500
32,600
84,600
44,300
39,200
99,200
54,600
0.1% 435,900 436,100
0.0% 13,855,300 13,855,400
0.3%
0.2%
-0.9%
0.0%
0.0%
0.3%
0.1%
0.2%
0.0% 435,800
0.0% 13,855,100
Bridge
37,100
44,200
32,600
84,600
44,300
39,100
99,200
54,700
0.3%
-0.5%
-0.9%
0.0%
0.0%
0.0%
0.1%
0.4%
0.0%
0.0%
Table 6 Summary of Nitrogen Oxides (NOx) in Casey Overpass Study Area
No-Build
9
12
8
23
12
9
26
13
112
3,550
AM Peak Period (3-hour)
At-Grade
13
112
3,550
9
12
8
23
12
9
26
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
Bridge
13
112
3,550
9
12
8
23
12
9
26
NOx (kg)
No-Build
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
10
13
10
24
14
11
28
15
125
3,880
PM Peak Period (3-hour)
At-Grade
15
125
3,880
10
14
9
24
14
11
28
0.0%
7.7%
-10.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
Bridge
15
124
3,880
10
13
9
24
14
11
28
0.0%
0.0%
-10.0%
0.0%
0.0%
0.0%
0.0%
0.0%
-0.8%
0.0%

Neighborhood
Hyde Park
Jamaica Plain
Mattapan
North Dorchester
Roxbury
Roslindale
South Dorchester
West Roxbury
Study Area Total
Regional Total
Neighborhood
Hyde Park
Jamaica Plain
Mattapan
North Dorchester
Roxbury
Roslindale
South Dorchester
West Roxbury
Study Area Total
Regional Total
Table 7 Summary of Volatile Organic Compounds (VOCs) in Casey Overpass Study Area
No-Build
11
17
11
32
17
12
36
17
153
4,140
AM Peak Period (3-hour)
17
12
36
17
At-Grade
11
17
11
32
153
4,140
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
17
12
36
17
Bridge
11
17
11
32
153
4,140
VOC (kg)
0.0%
No-Build
14
0.0%
0.0%
0.0%
19
13
32
0.0%
0.0%
0.0%
0.0%
19
15
39
20
0.0%
0.0%
171
4,540
PM Peak Period (3-hour)
19
15
39
20
At-Grade
14
19
13
32
171
4,540
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
Table 8 Summary of Fine Particulate Matters (PM
2.5
) in Casey Overpass Study Area
No-Build
700
900
600
1,700
800
700
2,000
1,100
8,500
278,300
AM Peak Period (3-hour)
At-Grade
700
900
600
1,700
800
700
2,000
1,100
8,500
278,300
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
Bridge
700
900
600
1,700
800
700
2,000
1,100
8,500
278,300
PM2.5 (g)
No-Build
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
800
1,000
700
1,900
1,000
900
2,200
1,200
9,700
305,100
19
15
39
20
Bridge
14
19
13
32
171
4,540
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
PM Peak Period (3-hour)
At-Grade
800
1,000
700
1,900
1,000
900
2,200
1,200
9,700
305,100
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
Bridge
800
1,000
700
1,900
1,000
900
2,200
1,200
9,700
305,100
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%