EPA-AA SDSB 79-31
Technical Report
Localized Air Quality Impacts
of Diesel Particulate Emissions
by
R. Dwight Atkinson
November 1979
NOTICE
Technical Reports do not necessarily represent final EPA
decisions or positions. They are intended to present tech-
nical analysis of issues using data which are currently
available. The purpose in the release of such reports is to
facilitate the exchange of technical information and to inform
the public of technical developments which may form the basis
for a final EPA decision, position Or regulatory action.
Standards Development and Support Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Office of Air, Noise and Radiation
U.S. Environmental Protection Agency
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TABLE OF CONTENTS
Page
List of Tables 3
List of Figures 5
Introduction 6
Section I: Summaries of Roadside Impact Studies . . 7
A. EPA-RTP Study . . . . 7
B. Southwest Research Institute Study ... 9
C. Toyota Motor Company Study . 18
D. General Motors Study .......... 18
E. Aerospace Corporation Study ...... 24
F. EPA CAMP-Site Study . . 32
Section II: Standardization of Roadside Impact ... 34
Studies
Section III: Summary and Conclusions . 40
A. Off-Expressway 40
B. Street Canyon * 41
C. Other , 42
References 43
Appendix 46
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LIST OF TABLES
Table 1 Particulate Concentrations - EPA-RTP.
Table 2 Vehicle Contribution to Ambient Air Particulate Concen-
trations on an Expressway (1-45 at Joplin Dr.) in
Houston, Texas - SwRI.
Table 3 Annual Arithmetic Mean Vehicle Contribution to Ambient
Air Particulate Beside an Expressway (1-10 at Silber) in
Houston, Texas - SwRI.
Table 4 Estimated Motor Vehicle Contributions to Total Partic-
ulate Concentrations in a Street Canyon, Houston St.
between Navarra and St. Mary's, San Antonio, Texas -
SwRI.
(
Table 5 Urban Freeway Exhaust Particulate Concentrations,
Projection Years - Aerospace.
Table 6 Urban Freeway Exhaust Particulate Concentrations,
Maximum Annual 24 Hours and Annual Geometric Means,
Best Estimate - Aerospace.
Table 7 Street Canyon Exhaust Particulate Concentrations, 1975
Baseline Year - Aerospace.
Table 8 Street Canyon Exhaust Particulate Concentrations,
Projection Years - Aerospace.
Table 9 Street Canyon Exhaust Particulate Concentrations, Worst
Case Metropolitan Geometry - Aerospace.
Table 10 Street Canyon Exhaust Particulate Concentrations,
Maximum Annual 24 Hour and Annual Geometric Means at
Various Elevations - Aerospace.
Table 11 Mobile Source CO and Diesel Particulate Ambient CO
Levels in Seven Selected Cities - EPA.
Table 12 1-Hour, 8-Hour Reasonable Case, and 24-Hour Concentra-
tion Modified Results - EPA-RTP.
-------
Table 13 On-Expressway, Beside-Expressway, and Street Canyon
Modified Results - SwRI.
Table 14 GM Modified Results - GM.
Table 15 Off-Expressway and Street Canyon Modifications -
Aerospace.
Table 16 CAMP-site Modifications - EPA.
Table A-l Vehicle Distribution and Roadway Split in Percentage by
Hour of Day for a Suburban Freeway - EPA-RTP.
Table A-2 Particulate Emission Rate (By Class) and Vehicle Type
Split by Fraction of Urban VMT - EPA-RTP.
Table A-3 Light Duty Diesel Emission Factors by Engine Model -
SwRI.
Table A-4 Percent of Total Diesel Sales for Various Models -
SwRI.
Table A-5 Exhaust Particulate Emission Factors for a Crowded
Expressway by Model Year, With Diesel Particulate
Regulations - SwRI.
Table A-6 Exhaust Particulate Emission Factors for a Crowded
Expressway by Model Year, Without Diesel Particulate
Regulations - SwRI.
Table A-7 Comparison of On-Freeway Emission Factors for Houston,
Texas - SwRI.
Table A-8 Urban Freeway Data Base - Aerospace.
Table A-9 Composite Emission Factors for Urban Freeway and Street
Canyon Analyses - Aerospace.
Table A-10 Information of CO Probes at CAMP sites - EPA.
Table A-ll Traffic Characterization and Emission Factors - EPA.
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LIST OF FIGURES
Figure 1. Source - Receptor Configuration for EPA-RTP Study.
Figure 2. 1-45 at Joplin, Houston, Texas - SwRI.
Figure 3. Physical Characteristics of Street Canyon - SwRI.
Figure 4. Relation between the Distance from the Edge of the Road
and the Density of the Particulate Emissions - Level
Area - Toyota.
Figure 5. Relation between the Distance from the Edge of the Road
and the Density of the Particulate Emissions - Middle
Storied Building Area - Toyota.
Figure 6.. Relation between the Density of the Particulate Emis-
sions at the Road Side and the Traffic of Diesel Vehi-
cles - Level Area - Toyota.
Figure 7. Relation between the Density of the Particulate Emis-
sions at the Road Side and the Traffic of Diesel Vehi-
cles - Middle Storied Building Area - Toyota.
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Introduction
A number of studies are available which attempt to predict the
level of diesel exhaust particulate along the roadway resulting
from the increased use of diesel engines as power plants for
light-and heavy-duty vehicles. Among these are reports prepared by
EPA,JL/j2/ the Southwest Research Inst itute ,_3/ General Motors
Corporation,^/ Toyota Motor Co.,j>/ and the Aerospace Corpora-
tion ,j>/
When trying to evaluate the results of these studies, problems
arise due to the lack of a consistent set of assumptions made by
the individual groups. The rate of diesel penetration into the
market, vehicle emission factors, traffic density and meteorolog-
ical conditions are among the variables encountered. This report
attempts to establish a broader base of comparison among these
studies than presently exists.
To effect this, each study will be altered so that all use
the same rate of dieselization and particulate emission factor.
The modification process simply consists of replacing the values of
these two parameters used in each study with the following set of
assumptions (based on the year 1990):
Light-duty emission factor: 1.0 gram particulate/mile
Heavy-duty emission factor: 2.0 grams particulate/mile
Light-duty dieselization level: Low - 9.6% of urban VMT
High - 15.9% of urban
Heavy-duty dieselization level: Low - 3.7% of urban VMT
High - 5.2% of urban VMT
This report consists of three basic sections; the first
provides a brief description of the various studies, the second
incorporates the standardizing assumptions in the modification
procedure, and the third compares the studies based on the changes
made in section two.
In order to facilitate reading of this report, only the most
essential tables have been included in the body of the text.
Other, supporting tables are located in the appendix and are
identified by the prefix A.
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Section I: Summaries of Roadside Impact Studies
A. EPA: "Reply to Request for Concentration Estimates near
Roadways Due to Mobile Source Emissions of Sulfuric Acid and Diesel
Particulates (TSP and BaP)"._l/
Model Used: HIWAYJ7/
Traffic Characterization: The traffic volume used in this
study assumed 100,000 vehicles per day for the Monday through
Friday work period. By applying the SAPPOLUT model,jJ/ hourly
vehicle distribution characteristics were determined for a suburban
freeway in an area with a population greater than 500,000. (See
Table A-l).
Receptor Locations: Five receptors were chosen in the EPA
study, each located on the inbound side of the freeway. This
choice of locations was done in order to maximize the effect of
peak hour (0700) traffic. (See Figure 1).
Meteorological Data; By studying CO concentrations measured
in Oakbrook, Illinois, Patterson^/ determined that maximum 8-hour
average concentrations occur for the eight consecutive hours ending
about 6 P.M. Corresponding meteorological data were: 2-5 m/sec
wind speeds, 0° - 50° wind fluctuations, and D-stability. For
the 24-hour periods with highest concentrations, winds were 2-7
m/sec, direction variability was 0° - 50°, and atmospheric stabil-
ity was nearly constant.
Summary of Meteorological Conditions
One-hour
Wind speed: 1 m/sec road-wind angle: 7°
Stability class: D: Initial mixing:* 5m
8-hour Worst Case
Wind speed (by hour): 4, 3, 2, 2, 2, 2, 2, 2 m/sec
Road-wind angle (by hour): 45°, 40°, 30°, 20°, 12°,
7°, 12°, 15°
Stability class: D
Initial mixing:* 5m
24-hour Worst case
Wind speed (by hour): 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3,
4,3,2,2,2,2,2,2,2,2,2,3,4, m/sec
"'Initial mixing refers to the region of space immediately after
the point of pollutant release in which turbulence is the pre-
dominant mode of dispersion.
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3.5m
OUTBOUND
I
MEDIAN
INBOUND
Receptor Number
1
2
3
4
5
Distance to Curb,(Deters)
4.75
24.75
44.75
64.75
94.75
Figure 1. Source-Receptor Confi^uration
Source: Reference I/
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A-2.
Road-wind angle (by hour): 20°, 30°, 30°, 20°, 30°, 30°,
20°, 12°, 15°, 30°, 40°, 45°, 40°, 30°, 20°, 12°, 7°,
12°, 15°, 15°, 20°, 30°, 40°, 45°
Stability class: D
Initial mixing: 5m
Emission Factors: Emissions by vehicle class are in Table
Dieselization Rate: The breakdown of urban VMT for 1990 by
vehicle class was taken from a PEDCo report ,10/ Table A-2 presents
this analysis.
Results: (See Table 1) The terms best and max refer to the
different dieselization rates found in Table 1. The low and high
terms refer to the HDVD (heavy-duty vehicle diesel) emission factors
in Table A-2. The first set of 8-hour concentration estimates are
obtained by multiplying 1-hour values by 0.7, as suggested in the
Indirect Source Guidelines.ll/
B. Southwest Research Institute Study:3/ "Study of Particulate
Emission from Motor Vehicles - A Report to Congress" (Draft)
Four separate scenarios were considered by SwRI in order to
analyze exposures at the local level. For the purposes of this
report, these scenarios will be referred to as: on a crowded
expressway, beside an expressway, in a street canyon and in a
parking area. The last of these will not be described due to its
highly specialized nature, making it difficult to compare with
other studies.
On a Crowded Expressway
Model Used: Chock's Simple Line Source Modell2/
Traffic Characterization: A portion of 1-45 at Houston, Texas
with a 5:30 p.m. vehicle count of 1494 vehicles per lane was used
for this study. (See Figure 2)
Receptor Location: Concentrations were computed for the outside
downwind lane.
Meteorological Data: An examination of recent five-year
meteorological data revealed that at 6 p.m., the wind was from the
ESE at 4 to 16 knots (2.06 to 8.23 m/sec) at 2.75° to 25.25°
relative to the road and stability was within plus or minus 1 class
of neutral 15% of the time. These conditions were chosen as model
inputs.
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Table 1
Particulate Concentrations
One-Hour Concentrations (milligrams per cubic meter)
Receptor
# ' '
1
2
3
4
5
Best, Low
.155
.096
.072
.058
.042
Best, High
.191
.118
.089
.071
.052
Max , Low
.294
.182
.137
.110
.080
Eight-Hour Concentrations (using conversion factor =
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
.109
.067
.050
.040
.029
Eight-Hour
.032
.023
.018
.016
.013
.020
.015
.012
.010
.008
.134
.082
.062
.049
.036
Reasonable Case
.039
.028
.022
.020
.016
24-Hour Scenario
.025
.018
.015
.012
.011
.207
.127
.095
.076
.055
Scenario
.061
.044
.034
.030
.025
.038
.028
.023
.019
.017
Max, Hi;
.345
.214
.160
.129
.093
.7)
.242
.149
.111
.089
.064
.071
.051
.040
.036
.029
.044
.033
.027
.022
.020
Source: Reference I/.
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NORTH
lanes are 12 feet wide
oedian is 20 feet wide
Figure 2 . 1-45 AT JOPLIN, HOUSTOM. TEXAS,
SHOWING WIND ANGLE LIMITS WITH
ROAD FOR ESE WIND.
Source: Reference 3/
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Emission Factors: Two sets of emission factors were consid-
ered; one scenario which assumed that the proposed light-duty
diesel standard (Federal Register 2/1/79) will be adopted as
proposed and another which considered the effect of no diesel
particulate regulations. The light-duty diesel emission factors
used for the first situation were 0.6 g/mile for 1981 and 1982
model years and 0.2 g/mile for 1983 and beyond. Emission factors
for the latter scenario were developed by considering the amount of
pollutants from individual vehicle models (see Table A-3), their
corresponding projected sales (Table A-4), and a breakdown of
annual travel. Tables A-5 and A-6 show the computed particulate
emission factors for a crowded expressway by model year. Composite
emission factors are found in Table A-7.
Dieselization Rate: Three estimates of the rate of diesel
penetration were used in this study. The "best" estimate assumes
that in 1985, 25% of GM's light duty sales will be diesel. Also,
it is assumed that 25% of total sales will be diesel in 1995. A
low estimate was prepared which considered the possibility of the
manufacturers not being able to meet the proposed light duty diesel
standards. This scenario held the diesel sales at the 1982 level.
A third "high" estimate dealt with the possibility of more strin-
gent fuel economy requirements by D.O.T. This would, according to
their projections, result in greater production of more fuel
efficient diesels. Sales would follow the "best" estimate growth
rates until 1983, where a linear increase leading to a 1995 diesel
sales penetration figure of 50% would begin. From 1995 through
2000, the diesel fraction of sales remains constant at 50%.
Results: Table 2 shows the results of the "On Expressway"
study.
Beside an Expressway
Model Used: Chock's line source model, modified by Sieyers
to yield annual arithmetic means, was used.13/
Traffic Characterization: The study site was 1-10 at Silber
Road on the west side of Houston. This portion of 1-10 runs due
east-west with four lanes in each direction. The average traffic
count for 1977 was 167,860 vehicles per day.
Receptor Location: The contributions to annual TSP levels at
1, 1~0~| 30~i 100, 200 and 500 meters from the road's northern edge
were computed.
Meteorological Data: Ambient particulate concentrations were
computed for each of 576 meteorological conditions. This number
was arrived at by considering the possible combinations of 16 wind
directions, six stability classes and six wind speed classes. The
frequency of occurrence of each particular meteorological combi-
nation was multiplied by the corresponding concentration in order
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TABLE 2 VEHICLE CONTRIBUTION TO AMBIENT AIR PARTICULATE
CONCENTRATIONS ON AN EXPRESSWAY (1-45 at Joplin Dr.)
IN HOUSTON, TEXAS
jVehicle Contributions, yg/m3
Diesel Part. 4 kts **
Year Regulations at 2.75°
1977
78.1
4 kts
at 25.25
baseline
49.6
Low Estimate of Light Duty
1985
1985
1990
1990
2000
2000
1985
1985
1990
1990
2000
2000
1985
1985
1990
199O
2000
2000
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
yes
no
57.4
62.0
47.1
62.0
47.9
70.8
Best Estimate of
57.8
63.9
49.8
70.1
53.6
90.4
High Estimate
58.2
64.7
52.1
78.5
61.6
116.8
36.5
39.4
29.9
39.4
30.4
45.0
Light Duty
36.7
40.6
31.6
44.5
34.0
57.4
16 Xts
at 2.75°
56.6
Dieselization
41.6
44.9
34.1
44.9
34.7
51.3
Dieselization
41.9
46.3
36.1
50.8
38.8
65.5
16 kts
at 25.25
16.5
12.1
13.1
9.9
13.1
10.1
15.0
12.2
13.5
10.5
14.8
11.3
19.1
of Light Duty Dieselization
37.0
41.1
33.1
49.8
39.1
74.2
42.2
46.9
37.7
56.9
44.7
84.6
12.3
13.7
11.0
16.6
13.0
24.7
* at outside, downwind lane .
**' wind speed and direction relative to expressway
Source: Reference 3/
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to weight the prediction. Houston wind data indicates that vehicle
emissions will be dispersed northward approximately 60% of the
t ime. .
Emission Factors and Dieselization Rate: The same scenarios
from the on expressway study were used here.
Results: Table 3 shows the results of the "Beside an Ex-
pressway" study.
In a Street Canyon
Model Used: The street canyon model by Johnson, et. al.14/
was the basis for this study. The model is based on helical air
circulation patterns over a street with buildings on both sides.
Traffic Characterization: The test city was San Antonio. The
street being modeled was Houston Street (eastbound one-way) between
cross streets Navarro and St. Mary's. "Canyon" width was 61
feet and the leeward side average building height was 111 feet.
Average daily traffic was approximately 15,300 vehicles per day.
For receptors 3 and 4 (residents), vehicle rate = 0.177 vehicles
per second. For receptors 1 and 2 (pedestrians), a peak rate of
0.354 vehicles per second was used.
Receptor Location: (Refer to Figure 3.) X^ = X2 = street
center-to-receptor 1 or 2 (pedestrian) distance = 28.8 feet. X3
= X^. = street center-to-receptor 3 or 4 (resident) distance =
30.5 feet.
Meteorological Data; U = rooftop wind speed = 10 mph (4.5
meters/sec). Wind direction is from the south-southeast (58° to
street direction).
Emission Factors:
National Fraction Total Particulate
Vehicle Type of VMT . Emission Factor g/mile
Light-duty gasoline 0.925 0.27
Light-duty diesel 0.001 0.99
Medium-duty truck 0.007 0.56
Heavy-duty gasoline 0.022 1.01
Heavy-duty diesel 0.040 .2.84
Motorcycles 0.005 0.08
Dieselization Rate: The same three low, best and high esti-
mates used in the on and beside an expressway studies were used
here.
Results: Table 4 contains the "Street Canyon" projections.
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TABLE 3 ." Annual Arithmetic Mean Vehicle Contribution
To Ambient Air Particulate Beside an Expressway
(1-10 at Silber) in Houston, Texas
Year
1977
Diesel Part.
Regulations
*3
Vehicle particulate contribution, annual arithmetic mean, jjg/jn
Distance from road edae
1m
12.4
10m
. 9.7
Low estimate of
1985
1985
1990
1990
2000
2000
Yes
No
Yes
No
Yes
No
9.1
9.8
7.5
9.8
7.6
11.2
7.2
7.7
5.9
7.7
6.0
8.8
30m
Baseline
6.2
100m
3.0
200m
1.8
500m
0.8
light duty dieselization
4.5
4.9
3.7
4.9
3.8
5.6
Best estimate of light duty
1985
1985
1990
1990
2000
2000
1985
1985
1990
1990
2000
2000
Yes
No
Yes
No
Yes
No
Yes
Mo
Yes
No
Yes
No
9.2
10.1
7.9
11.1
8.5
14.3
High
9.2
10.2
8.2
12.4
9.8
18.5
7.2
8.0
6.2
8.7
6.7
11.3
4.6
5.1
3.9
5.5
4.2
7.2
estimate of light duty
7.3
8.1
6.5
9.8
7.7
14.6
4.6
5.1
4.1
6.2
4.9
9.2
2.2
2.4
1.8
2.4
1.8
2.7
dieselization
2.2
2.4
1.9
2.7
2.0
3.4
dieselization
2.2
2.5
2.0
3.0
2.3
4.4
1.3
1.4
i.i
1.4
1.1
1.6
1.3
1.4
1.1
1.6
1.2
2.0
1.3
1.5
1.2
1.8
1.4
2.6
0.6
0.6
0.5
0.6
0.5
0.7
0.6
0-7
0.5
0.7
O.G
0.9
0.6
0.7
0.5
0.8
0.6
1.2
On northside of the expressway which runs east-west
Source: Reference 3/
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i -. *.".". " ":'.
Figure 3 . Physical characteristics of street canyon
Source: Reference 3/
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TABLE 4 Estimated Motor Vehicle Contributions to Total Participate Concentrations in a
Street Canyon, Houston Street between'Mhvarro and St. -Mary's.'San Antonio. Texas
Leeward side concen--
trations (AXL), yg/m
Windward side concen*
trations (AXW), yg/m
Year
1977
1985
1990
2000
Regulations
in effect
No
Yes
. No
Yes
No
Yes
No
Dieselization
estimate
as is
low
best
high
low
best
high.
low
best
high
1 ow
best
high
low
best
high
low
best
high
Composite emission
factor, g/veh. mi
0.39
0.26
0.26
0.26
0.30
0.31
0.32
0.22
0.2.4
0.26
0.31
0.37
0.43
0.19
0.24
0.31
0.31
0.46
0.66
receptor 1
pedestrian
13.
8.6
8.6
8.6
9.9
10.
11.
7.3
7.9
8.6
10.
12.
14.
6.3
7.9
10.
10.
15.
22.
receptor 3
resident
4.8
3.2
3.2
3.2
3.7
3.8
4.0
2.7
3.0
3.2
3.8
4.6
5.3
2.4
3.0
3.8
3.8
5.7
8.2
receptor 2
pedestrian
6.2
4.1
4.1
4.1
4.7
4.9
5.1
3.5
3.8
4.1
4.9
5.9
6.8
3.0
3.8
4.9
4,9
7.3
10.
receptor 4
resident
2.5
1.7
1.7
1.7
1.9
2.0
2.1
1.4
1.5
1.7
2.0
2.4
2.8
1.2
1.5
2.0
2.0
2.9
4.2
Source: Reference 3/
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C. Toyota Motor Co.: Toyota Comment on the EPA Proposed Partic-
ulate Regulation for Light-Duty Diesel Vehicles.^/
y
Model Used: A diffusion factor of
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Fig. £ "Relation between the distance from the edge of the road
and the density of the particulate emissions
15-t
t"
tr
-------
Fig. 5 . Relation between the distance from the edge of the road
and the density of the particulate emissions
«*>
I
'oi'
u
(1)
(U
X
(0
c
o
H
tn
en
-f-4
W
(U
4J
a
o
H
4J
H
Id
CU
JJ
H
-------
Fig. 6 Relation between the density of the particulate emissions
at the road side and the traffic of diesel vehicles.
0
tn
ITJ
M
0)
H
U
(0
-------
Fig. 7 Relation between the density of the particulate emissions
at the road side and the traffic of diesel vehicles.
0)
tP
cd
V4
a)
>
cd
>t
cd
0)
en
c
o
H
in
en
0
4J
d
o
-H
4J
V4
td
cn
C
-------
Results: 13.5 micrograms per cubic meter.
GM states that since the worst case meteorology cannot be
sustained for a 24-hour period, the highest 24-hour concentration
would be approximately one-half of this hourly value, or 6.8
mg/m^.
Scenario 2: This analysis is based on case B from Chapter IV
of the Draft Regulatory Analysis.15/
Traffic Characterization: 25% of the light-duty fleet
is assumed to be diesel for the year 2000; 1% per year growth rate
for VMT is used.
Receptor Location: "Roadside".
Meteorological Conditions: No details available.
Emission Factor: 0.2 g/mile.
Results : 24-hour roadside maximum: Major cities - 8.8
micrograms per cubic meter; Mid-size cities - 2.5 micrograms per
cubic meter.
The 24-hour roadside estimates are based on the highest
observed 24-hour CO measurement (e.g., for a major city: 33 ppm in
Chicago in 1966) .J_6_/ No details of the methodology employed in
this correlation are provided.
Worst-case Scenario: This evaluation describes Manhattan if
all its taxis were diesel.
Model: Street Canyon Model.14/
Traffic Characterization: Six-lane roadway with traffic
density of 500 cars per hour per lane.
Meteorological Conditions: No details available other than
"adverse."
Emission Factor: 1.0 g/mile
Dieselization Rate: 60% of total traffic (100% of taxis).
Results: 127 micrograms per cubic meter for a 1-hour average;
71 micrograms for a 24-hour average.
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E. Aerospace Corporation: "Assessment of Environmental Impacts of
Light-Duty Vehicle Dieselization".6/
Localized air quality impact analyses were performed to deter-
mine effects from an urban freeway, an urban street canyon and an
enclosed parking garage. The last of these is mentioned for
completeness and will not be discussed here since its scope is
specialized beyond the needs of this study.
Urban Freeway:
Approach : Impact estimates were based on an empirical param-
eter ₯, referred to as the pollutant concentration index. It is
defined as Y^Z = ^XZ ~ C^), where GXZ is the concentration
Q
of a measured pollutant at distance X horizontally from the roadway
and distance Z vertically above the ground, C^ is the background
concentration and Q is the vehicle source emission flux (product of
emission factor and traffic count). The assumption is made that
diesel particulate will disperse in the same manner as gases.
Thus, Y values obtained from CO and tracer gas measurements can be
used to determine diesel particulate concentrations by substituting
the appropriate diesel emission factor. Several studies to deter-
mine the roadside distribution of CO and tracer gases were used by
Aerospace in order to determine Y values. These are listed in
Table A-8 together with a brief description of each.
Traffic Characterization: In connection with the 50 percen-
tile ₯ values (meant to represent typical dispersion conditions) a
maximum traffic density of 12,000 vehicles per hour was used. To
determine 24-hour maximum concentrations occurring once a year,
different ₯ values were chosen. These corresponded to the 99.73 ₯
percentile ((1 - 1 ) x 100). Data from GM was used to obtain
365
these values because they were the most extensive available. The
traffic count for this scenario was 7,850 vehicles/hour based on a
24-hour integration of traffic flow on an 8-lane urban freeway in
Los Angeles.
Receptor Locations: Monitoring data were analyzed at or near
three locations: 1) the roadway median, 2) 100 feet from the
roadway, and 3) 300 feet from the roadway. These sites were chosen
to represent exposures to highway users, people employed by road-
side businesses and inhabitants of nearby homes.
Emission Factors : Composite emission factors were based on
Manhattan data and were calculated from the following equation:
EP =l(Dump)cnpe
e,c , where p denotes the pollutant for
£(VMT)cnpe
e,c
-------
class c vehicles with engine type e in calendar year n. Table A-9.
lists the emission factors so determined.
Dieselization Rate: Three rates of light-duty vehicle diesel-
ization were investigated: the 1% base case, 10% and 25% rates for
the year 2000.
Results: Urban freeway exhaust particulate projections using
the 50 percentile y and the 99.73 percentile Y (worst case) are in
Tables 5 and 6. Note that the latter is in terms of the annual
geometric mean and maximum annual 24-hour concentrations.
Street Canyon '
Approach: The same basic methodology used in the urban
freeway analysis was used here. The data base (used to determine
the pollutant concentration index) consisted of four studies, each
designed to determine the CO distribution in the urban street
canyon. SRI International performed two of these studies at sites
in St. Louis, Missouri22/ and San Jose, California. 23_/ Vanderbilt
University 24/ and the city of New York25/ conducted the remaining
two investigations.
Traffic Characterization: Traffic counts of 500, 1,000, 1,500
and 2,000 vehicles per hour were used to evaluate the 1975 base
year (50 percentile y values were used). When the effects of
changes in the rate of diesel penetration were studied, the traffic
count was held constant at 2,000 vehicles per hour. Annual maximum
24-hour and annual geometric mean values were determined at a
traffic count of 936 vehicles per hour. This traffic density as
well as the 99.7 percentile y values were based on the St. Louis
study referenced earlier.
Receptor Locations: For the base 1975 year, pollutant levels
at heights of 6, 15, 30, 60 and 120 feet were determined. Concen-
trations were evaluated for other scenarios at heights of 6, 30 and
90 feet above street level. A special worst case street level
scenario was also evaluated based on a CO monitor in downtown
Manhattan.
Emission Factors: The same factors used in the urban freeway
scenario were applied to this portion of. the study.
Dieselization Rate: The three scenarios used in the urban
freeway analysis were applied here.
Results: Tables 7 through 10 give the results of this study.
-------
Table 5
"Urban Freeway Exhaust Particulate Concentrations,
Projection Years
LDV
Diesel-
ization
Rate
B/C
(1%)
10%
25%
25%
. 100%
Taxis
Pro-
jection
Year
1975
1985
1990
2000
1985
1990
2000
1-985
1990
2000
1985
1990
2000
Roadway
Median
Diesel
12.2
19.6
27.1
42.0
24.7
33.1
48.1
34.0
43.5
57.9
55.2
55.2
67.4
Total*
86,7
38.3
39.5
46.9
43.5
45.2
52.7
52.1
54.7
61.9
73.7
66.5'
71.4
Distance From Edge of Roadway, Ft .
13
Diesel
17.8
28.6
39.5
61.3
36.1
48.3
70.1
49.6
63.4
84.4
80.6
80.6
98.3
Total 'C
126.4
55.9
57.5
68.5
63.4
65.9
76.9
76.0
79.8
90.3
107.5
97.0
104.2
100
Diesel
6.6
10.5
14.6
22.6
13.3
17.8
25.9
18.3
23.4
31.1
29.7
29.7
38.4
Total*
46.6
20.6
21.2
25.2
23.4
24.3
28.3
28.0
29.4
33.3
39.6
35.7
38.4
300
Diesel
2.8
4.5
6.2
9.6
5.7
7.6
11.0
7.8
10.0
13.3
12.7
12.7
15.5
Total*
19.9
8.8
9.0
10.8
10.0
10.4
12.1 .
11.9
12.5
14.2
16.9
15.2
16.3
50th Percentile values based on generalized i/; profile (Figure 3.2-2),A'g/m above ambient,
traffic count = 12,000 veh/hr.
'Total mobile source exhaust emission contribution.
Source: Reference 6J
-------
Table 6
Urban Freeway Exhaust Particulate Concentrations, Maximum
Annual 24-Hour and Annual Geometric Means. Best Estimate
Dloocl-
tzallon
Rate
Baso Caao
(1%)
10%
LDV
25%
LDV
2 5% LDV
1-
100% .
Taxis
Pro-
jection
Year
1975
1985
1990
2000
1985
1990
2000
1985
1990
2000
1985
1990
2000
Roadway Median
Dioool Exhaust
Participates
24-Hr
21.0
33.6
46.5
72.2
42.5
56.8
82.6
58.4
74.6
99.4
95.0
95.0
115.7
Annual
7.0
11.2
15.5
24. I
14. 2 -
19.0
27.6
19.5
24.9
33.2
31.7
3J.7
38.6
Total Exhaust
Participates
24 -Hi-
148.8
65.7
67.6
80.6
74.6
77.6
90.4
89.5
94.0
106.3
126.5
114,2
122.6
Annual
49.6
21.9
22.6
26.9
24.9
25.9
' 30. 1
29.8
31.4
35.4
42.2
38. 1
40.9
Distance From Roadway Edge, Ft
13
Diosol Exhaust
Parliculatcs
24-Hr
27. 1
43.3
60.0
93.0
54.7
73.4
106.4
75.2
96.3
128. 1
122.4
122.4
149. 1
Annual
9.0
14.4
20.0
31.0
18.2
24. 4
35.5
25. 1
32.1
42.7
40.8
40.8
49.7
Total Exli.iual
Particulntcs
24-Hr
191.8
84. 8
87.3
103.9
96.2
100.0
116.7
115.4
121. 1
137. I
163.2
147.2
158. 1
Annual
64.0
28.3
29. I
34.6
32. 1
33.3
38.8
38.5
40.3
45.6
54.5
49.0
52.6
100
Diesel Exhauut
Participates
24-Hr
10.7
17.2
23.8 '
36.9
21.7
29. 1
42.2
29.8
38.2
50.8
48.6
48.6
59.2
Annual
3.f,
5.7
7.9
12.3
7.2
9.7
14. 1
9.9
12.7
16.9
16.2
16.2
19.7
Total Exhaust
Particulatea
24-Hr
76. I
33.6
34.6
41.2
38. 2
39.7
46.2
45.8
48.0
54.3
64.7
58.4
62.7
Annual
25.4
11.2
11.5
13.7
12.7
13.2
15.4
15.3
16.0
18. 1
21.6
19.4
20. 8
JOO
Diesel Exhauut
Particulars
24 -Hi-
7. 0
11.2
15.5
24. 1
H.2
19. 0
27.6
19.5
24.9
33.2
31.7
31.7
38.6
Annual
2. 3
3.7
5.2
8. 0
4.7
6.3
9.2
6.5
8. 3
11.0
10.6
10.6
12.9
Total Exhauut
Particulars
24-Ilr
49. C
21. 9
22.6
26. 9
24.9
25.9
30. 1
29.8
31.4
35.4
42. 2
38. 1
40.9
Annual
If.. 5
7. J
7.5
9.0
H. 3
U.6
10. 1
9.9
1 0. 4
11. 8
14. 1
U.7
13.6
Values referenced to representative I// characteristic {Figure 3. 2-2), # g/m above ambient, traffic count = 7850 vch/hr.
TSP Air Quality Standards
Annual Geometric
Mean
Federal Primary/Secondary
California
24-Hr
260/150
100
75/60
60
Source: Referenced/
-------
Table
Street Canyon Exhaust Partrculate Concentrations, 1975 Baseline Year
Traffic Count
(Veh/Hr)
2000
1500
1000
500
Height Above Street, ft
6
Diesel
4.3
3.3
2.2
1.1
*
Total
30.7
23.0
15.4
7.7
15 . -
Diesel
3.9
2.9
2.0
1.0
*
Total
. 27.7
: 20. 8
13.8
6.9
30
Diesel
'3.1
2.4
1.6
0.8
Total*
22.3
16.7
11.1
5.6
.60
Diesel
2.3
1.7
1.2
0.6
Total""
16.2
12.2
8.1
4.1
120
Diesel
1.2
0.9
0.6
0.3
>'.<
Total
8.' 4
6.3
4.2
2.1
50th percentile values, based on generalized 0 profile (Figure 3.3-2)$ M g/m above ambient
Total mobile source exhaust emission contribution
Source: Reference 6/
-------
Table' 8
Street Canyon Exhaust Partlculate Concentrations, Projection Years
LDV
Dieselization
Rate
Baseline
(1%)
10%
25%
25% PC
+
100% Taxis
Projection
Year
1975
1985
1990
2000
1985
1990
2000
1985
1990
2000
1985
1990
2000
Height Above Street, ft
6 '
Diesel
4.3
6.9
9.6
14.9
8.8
11.7
17.0
12.0
15,4
20.5
19.6
19.6
23.9
*
Total
30.7
13.6
14.0
16.6
15.4
16.0
18.7
18.5
19.4
21.9
26.1
23.6
25.3
30
Diesel
3.1
5.0
7.0
10.8
6.4
8.5
12.4
8.7
11.2
14.9
14.2
14.2
17.3
*
Total
22.3
9.8
10. 1
12.1
11.2
11.6
13.5
13.4
14.1
15.9
18.9
17.1
18.4
90
Diesel
i
1.7
2.7
3.8
5.8
3.4
4.6
6.7
4.7
6.0
8.0
7.7
7.7
9.4
Total"'
12.0
5.3
5.5
6.5
6.0
6.3
7.3
7.2
7.6
8.6
10.2
9.2
9.9
50th percentile values, based on generalized ^ profile (Fieujre. 3.3-2).
above ambient; traffic count = 2000 veh/hr
#
Total mobile source exhaust emission contribution
Source: Reference 6/
-------
Table 9
Street Canyon Exhaust Particulate Concentrations,
Worst Case Metropolitan Geometry
LDV
Dieselization
Rate
Baseline
(1%)
10%
25%
25% PC
+
100% Taxis
Projection
Year
1975
1985
1990
2000
1985
1990
2000
1985
1990
2000
1985
1990
2000
Particulate Concentration
(/*g/m above ambient)
Diesel
6.9
' 1.1.0
15.3
23.7
14.0
18.7
27.1
19.2
24.5
32.6
31.2
31.2
38.0
Total"
48.9
21.6
22.2
26.5
24. 5
25. 5
29. 7
29.4
30.9
34.9
41,6
37.5
40.3
Based on 50th. percentile CO concentrations at curb-side receptor at
110 East 45th Street, Manhattan '
*
Total mobile source exhaust emission contribution
Source: Reference 6/
-------
Table 10
Street Canyon Exhaust Particulato Concentrations, Maximum
Annual 24-Hour and Annual Geometric Means at Various
Elevations
t
DiuuuHzation
Kale
25% LDV
2 5% LDV +
100% T.ixis
'
Pro-
jection
Year
1985
1990
2000
1985
1990
2000
Height Above Street
6 '
Diesel
IJartlculatea
24-Hr
21.3
27.2
36.2
34.5
34.5
42.1
Annual
7.1
9.0
12.0
11.5
11.5
14,0
Total
Participates
24-Hr
32.5
34.1
38.6
46.0
41.5
44.6
Annual
10.8
11.4.
12.9
15.3
13.8
14.9
30
Diesel Total
Pn rticul.itca Pa rlicul.-ilus
24-Hr
17.1
21.9
29.1
27.9
27.9
33.9
Annual
5.7
7.3
9.7
9.3
9.3
11.3
24-Hr
26.2
27.7
31.2
37. f
33; 5
36.0
Annual
8.8
9.2
10.4
12.4
11.2
12.0
90
Dicaul Total
Particulars P.i rtlculatcn .
24-Hr
10.3
13.1
17.4
16.7
16.7
20.4
Annual
3.4
4.4
5.8
5.6
5.6
6.8
24-Hr
15.7
16.5
18.7
22.3
20.1
21.6
Annual
5.2
5.5
6.2
7.4
6.7
7.2
Values based on St. Louis Hold study data, H g/ni above ambient.
-\ . ' ' '
TSP Air Quality Standards
24-Hr
Federal Primary/Soconary
Californi;i
260/150
100
Annual Gcomotrlc
Mean
75/60
60
Source: Reference 6/
-------
F. CAMP-site Evaluation - EPA "Relative Impact of CO and Parti-
culate on Urban Air Quality"2/
Approach: Carbon monoxide monitoring records at CAMP-sites in
seven major cities were used as a data base for this study. Since
82 - 97% of the CO in these cities originates from mobile sources,
replacing the appropriate CO emission factor with the desired
diesel particulate emission factor (weighted for VMT) converts CO
concentrations into particulate concentrations.
Receptor Locations: See Table A-10.
Emission Factor and Traffic Characterization: See Table A-ll.
In order to convert 1967 ambient CO levels to 1990 ambient particu-
late levels, it was necessary to assume growth in the urban vehicle
miles traveled parameter. An increase of 41.4% was assumed based
on a 1.5% per year increase, compounded.
Results: The ratio of urban diesel particulate emissions
(1990) to CO emission (1967) should be 0.0018, based on the above
procedure. The CO and TSP levels for the seven cities of interest
are in Table 11.
-------
Table 11
Ambient CO and Diesel Particulate Levels in Seven Selected Cities
City
Chicago
Philadelphia
Denver
St. Louis
San Francisco
Cincinnati
Washington, D.C.
1967
Ambient CO
Level (Milligrams
Per Cubic Meter)* 16/
13.5
7.2
7.1
5.7
5.0
4.9
3.8
1990
Ambient Diesel Part.
Levels (Micrograms
per Cubic Meter)
24.3
13.0
12.8
10.3
9.0
8.8
6.8
Annual geometric mean of 24-hour averages.
-------
Section II: Standardization of Roadside Impact Studies
As stated in the introduction, attempts to place the studies
on more common ground center around substituting the same level of
diese1ization and exhaust particulate emission factor for the
values of these parameters used in each study. These standardizing
quantities, listed below, represent expected conditions for the
year 1990.
Light-duty emission factor: 1.0 gram/mile
Heavy-duty emission factor: 2.0 grams/mile
Light-duty dieselization level:
Low estimate - 9.6% of urban VMT
High estimate - 15.9% of urban VMT
Heavy-duty dieselization level:
Low estimate - 3.7% of urban VMT
High estimate - 5.2% of urban VMT
Urban VMT growth rate (where- applicable) - 1 % per year,
compounded.
The roadside diesel particulate concentrations reported in the
Tables 12-16 reflect the use of these numbers. The basic assumption
has been made, as has been done in all of the studies being ex-
amined here, that the air quality impact is proportional to the
emission level. For example, if the emission factors and VMT
breakdown (low estimate) shown above are combined, the average
diesel particulate emission factor is 0.17 gram per urban VMT for
the low estimate case. In the last study examined in the previous
section (EPA, 2/), the average diesel particulate emission factor
was 0.121 gram per urban VMT (see Table A-ll). For this reason,
the impacts shown in Table 11 should be increased by 41%. However,
the EPA study assumed a 1.5% per year growth rate for urban VMT,
while the standard scenario above specifies a 1% per year growth
rate. Over the 23 years in question (1967-1990), this difference
would result in a 12% difference in the projected impacts. Com-
bining the two impacts shown in Table 11 should be increased by 25%
to convert the previous results in the standard scenario.
Toyota represented two scenarios in their comment, one for a
"level area" and another for a "middle storied building area".
However, the two graphs depicting their respective conclusions are
identical (refer to Figures 4 and 5 of this document). Since it is
unreasonable to expect these data to be the same, an inadvertant
error on the part of Toyota personnel is probably the cause.
Because Toyota did not provide details of the conversion from
hourly averages to yearly averages it was not possible to determine
which of the two scenarios was properly labeled and which was not.
Thus, modification of their results are not included in this
report.
-------
Table 12
Modified Results of
"Reply to Request for Concentration Estimates
Near Roadways Due to Mobile Source Emissions of
Sulfuric Acid and Diesel Particulates (TSP and BaP)" - EPA I/
Projected 1990 1-Hour Concentration (micrograms per cubic meter)
Receptor # Light-Duty Heavy-Duty
1 (4.75 m to curb) 95-155 72-101
2 (24.75 m to curb) 58-96 45-63
3 (44.75 m to curb) 43-72 33-47
4 (64.75 m to curb) 34-58 27-38
5 (94.75 m to curb) 26-42 19-27
Projected 1990 8-Hour Reasonable Case (micrograms per cubic meter)
Receptor # Light-Duty Heavy-Duty
1 (4.75 m to curb) 20-33 15-21
2 (24.75 m to curb) 14-23 11-15
3 (44.75 m to curb) 11-18 8-12
4 (64.75 m to curb) 10-16 7-10
5 (94.75 m to curb) 8-13 6-8
Projected 1990 24-Hour Concentration (micrograms per cubic meter)
Receptor # Light-Duty Heavy-Duty
1 (4.75 m to curb) 12-20 9-13
2 (24.75 m to curb) 9-15 7-10
3 (44.75 m to curb) 7-12 6-8
4 (64.75 m to curb) 6-10 5-7
5 (94.75 m to curb) 5-8 4-5
-------
Table 13
Modified Results of
"Study of Particulate Emissions from
Motor Vehicles - A Report to Congress" - SwRI 3/
Projected 1990 On-Expressway Concentrations
(micrograms per cubic meter)
Light-Duty
Heavy-Duty
4 Kts*
at 2.75°
36.7-61.1
28.4-39.8
4 Kts
at 25.25°
23.3-38.8
18.0-25.3
16 Kts
at 2.75°
26.5-42.2
20.6-28.8
16 Kts
at 25.25
7.7-12.9
6.0- 8.4
Wind speed and direction relative to road
Projected 1990 Beside-Expressway Concentrations
(annual arithmetic mean, micrograms per cubic meter)
Distance From Roadway (Meters)
Light -Duty
Heavy-Duty
Light-Duty
Heavy-Duty
1m 10 m .30 m
5.8-9.6 4.6-7.6 2.9-4.8
4.5-6.3 3.5-5.0 2.2-3.1
Projected 1990 Street Canyon
(micrograms per cubic
Leeward Side
Receptor #1 Receptor #2
(Pedestrian) (Resident)
5.8-14.1 2.2-5.4
4.5- 9.2 1.7-3.5
100 m 200
1.4-2.4 .8-1
1.1-1.5. .6-
Concentrat ions
meter)
Windward
Receptor #3
(Pedestrian)
2.8-6.9
2.2-4.5
m 500 m
.4 .4-. 6
.9 .3-. 4
Side
Receptor #4
(Resident)
1.1-2.8
.9-1.8
-------
Table 14
Modified Results of
"General Motors Response to EPA Notice
of Proposed Rulemaking on Particulate
Regulations for Light-Duty Diesel Vehicles" - GM 4/
Projected 1990 Hourly Maximum Concentration at Three Meters Above
Ground, 3.8 Meters from Road (micrograms per cubic meter)
Light-Duty: 5.2-8.6
Heavy-Duty: 1.0-5.6
Projected 1990 24-Hour Roadside Maximum - Based on CO Measurements
(micrograms per cubic meter)*
Major Cities Mid-Size Cities
Light-Duty 15.2-25.3 4.3-7.2
Heavy-Duty 11.7 - 16.5 3.3 - 4.7
* A factor of 0.9 was used to convert the traffic count for the
year 2000 (GM basis) to the 1990 scenario.
The GM worst case (Manhattan-Taxi) scenario was not modified
due to its highly specialized nature.
-------
Table 15
Modified Results of
"Assessment of Environmental Impacts of
Light-Duty Vehicle Dieselization" - Aerospace Corporation 6/
Projected 1990 Off-Expressway Concentrations
(Micrograms Per Cubic Meter) .___
24-Hour Max Annual Geo. Mean
30 Meters
from Road:
Light-Duty 24.1-40.3 8.1-13.4
Heavy-Duty 18.7-26.3 6.2- 8.8
91 Meters
from Road:
Light-Duty 15.8-26.3 5.3-8.7
Heavy-Duty 12.2-17.1 4.1 - 5.7
Projected 1990 Street Canyon Concentrations
(Micrograms Per Cubic Meter)
24-Hour Max Annual Geo. Mean
1.8 Meters
above Street:
Light-Duty 17.3 - 28.7 5.7 - 9.6
Heavy-Duty 13.3 - 18.7 4.4 - 6.2
9.1 Meters
above Street:
Light-Duty 13.9 - 23.2 4.6 - 7.7
Heavy-Duty 10.7 - 15.1 3.6 - 5.0
27.4 Meters
above Street:
Light-Duty 8.3 - 13.9 2.8 - 4.6
Heavy-Duty 6.4 - 9.0 2.1 - 3.0
-------
Table 16
Modified Results of
"Relative Impact of CO and
Particulate on Urban Air Quality" - EPA _2/
Projected 1990 CAMP Site Concentrations
(annual geometric means,* micrograms per cubic meter)
City Light-Duty Heavy-Duty
Chicago 17.0 - 28.4 13.2 - 18.5
Philadelphia 9.1 - 15.1 7.0 - 9.9
Denver 9.0 - 14.9 6.9 - 9.7
St. Louis 7.2 - 12.0 5.6 - 7.8
San Francisco 6.3 - 10.5 4.9 - 6.8
Cincinnati 6.2 - 10.3 4.8 - 6.7
Washington, D.C. 4.8 - 8.0 3.7 - 5.2
* An increase in VMT of 25.7% (based on a compounded 1% per
year growth rate) from the baseline 1967 year was assumed.
-------
Section III: Summary and Conclusions
The purpose of this report was to make the various studies on
the localized air quality impact of diesel particulate emissions
more comparable with one another. This was done by focusing on the
year 199.0 and applying certain standardizing assumptions. These
included using low and high estimates of dieselization, 9.6 and
15.9%, for the light-duty fraction of urban vehicle miles travelled
(VMT) and 3.7 and 5.2% for the heavy-duty instead of the corres-
ponding values used in each study. Further, emission factors
originally implemented were replaced by the following: 1.0 gram
per mile for light-duty diesel vehicles and 2.0 grams per mile for
heavy-duty diesels. From the studies so modified one can see a
range of predicted concentrations which varies both with the
exposure duration and receptor location (refer to Section I). It
is noted that most studies investigated off-expressway and street
canyon concentrations; these then are the focal points for compar-
isons in this summary. All concentrations cited hereafter (except
the GM worst case study) reflect modifications made in Section II.
A. Off-Expressway The EPA report yielded predictions on 1-hour,
8-hour, and 24-hour bases at locations from 4.75 to 94.75 meters
from the roadway.jY The traffic count in this study was 100,000
vehicles per day. It was determined that a 1-hour concentration of
58-96 micrograms per cubic meter would occur approximately 25
meters from the roadway due to light-duty diesels alone. Simi-
larly, 8-hour and 24-hour light-duty particulate concentrations of
14-23 and 9-15 micrograms per cubic meter were projected for the 25
meter site. The same receptor location, approximately 25 meters
from the roadway, was used in other reports as well.
Southwest Research Institutes/ estimated diesel particulate
concentrations at distances from 1-500 meters from the curb (in
addition to a street canyon study and an on-expressway evalua-
tion). At a distance of 30 meters from a road^way carrying 9000
vehicles per hour, the annual arithmetic mean particulate concen-
tration from light-duty diesels was 2.9-4.8 micrograms per cubic
meter. Aerospace's off-expressway study, based on actual moni-
toring data, found annual maximum 24-hour concentrations of 24.2-
40.3 micrograms per cubic meter and annual geometric mean values of
8.1-13.4 micrograms per cubic meter at the 30 meter distance.^/
The role of meteorology cannot be overlooked when explaining
discrepancies among the three aforementioned off-expressway
studies. The EPA report attempted to duplicate conditions which
led to high CO concentrations measured in Oakbrook, Illinois.
Southwest used a composite of 576 meteorlogical conditions at the
study site (Houston); each weighted according to its frequency of
occurrence. Such procedure led to the use of a typical meteoro-
logical scenario in their study. However, the Houston test site
-------
was selected partly because of its perpendicular orientation to
prevailing winds (a condition which maximizes off-expressway
concentrations). Thus, both the EPA and Southwest studies were
designed to represent adverse - yet different - meteorological
conditions. Since the Aerospace study draws upon several inde-
pendent tracer gas experiments, it does not represent a specific
meteorological scenario; rather, an average scenario resulting from
contributions by each constituent experiment is built into the
study's framework. From the above discussion, it cannot be con-
cluded that any single report used meteorological conditions more
viable than another's since each represents conditions that could
easily occur at other locations.
In addition to obvious differences in traffic volume, much of
the disparity among the three off-expressway studies can be ex-
plained by the inherent differences among the various dispersion
modeling aproaches taken. EPA's study was based on the HIWAY
line source dispersion model;_7/ Southwest Research Institute used a
modified version of GM's line source model developed by Chock;12/
and Aerospace Corporation relied on tracer gas surrogate to estab-
lish the relationship between concentration and source strength.
In a study performed for EPA by the New York Department of Envir-
onmental Conservation in which eight line source dispersion models
were evaluated, GM's yielded the best correlation with tracer gases
(HIWAY was one of the models investigated).26/ One would therefore
expect the Southwest study to yield more reliable results than the
EPA report since the former was based on GM's model. Aerospace's
findings should be superior to either since their study was based
directly on measured tracer gas dispersion characteristics rather
than an empirical representation of idealized dispersion.
B. Street Canyon Projected street canyon concentrations of
light-duty diesel particulate were determined in reports by GM,
Southwest Research, and the Aerospace Corporat ion._4/,_3/ ,J57 GM
attempted to evaluate the impact on Manhattan air quality of an all
diesel taxi fleet. Using Dabberdt's Gaussian Street Canyon
Model,Jj8/ they estimated a 24-hour average diesel particulate
concentration of 71 micrograms per cubic meter associated with a
traffic volume of 3,000 vehicles per hour (60 percent diesel).
Since their report did not include a discussion of meteorological
inputs (other than the word "adverse"), receptor location, or
street geometry, it cannot be fully evaluated or compared with the
other street canyon studies.
Southwest also used the Dabberdt model, but they provided
sufficient details to allow adequate interpretation. In their
study, it was estimated that pedestrians on the leeward side of the
street would be exposed to a continual concentration of 5.8-14.1
micrograms of light-duty diesel particulate per cubic meter (given
a traffic flow of approximately 1,274 vehicles per hour).
The Aerospace report yielded similar pedestrian exposure
-------
results, even though their methodology was entirely different: an
annual geometric mean of 5.7-9.6 micrograras per cubic meter (based
'on a traffic volume of 936 vehicles per hour. As was the case with
their off-expressway study, Aerospace relied on tracer gas experi-
ments to determine the relationship between source strength and
receptor concentration. By not relying totally on the rigid nature
of a mathematically simulated source-receptor relationship, condi-
tions more representative of everyday exposure scenarios are
represented. The simple technique of substituting diesel emission
factors for those of the tracer gases 'should be superior to the
more complex Gaussian dispersion approach.
C. Others The remaining two reports (Toyota's could not be
modified, see Section II), GM's roadside study4/ and the EPA
CAMP-site study, 2j represent exposure estimates generally closer
to the roadway than the 25-30 meter range. GM looked at a location
3 meters above ground and 3.8 meters from the road. For a 4lane
road carrying 25,000 vehicles per day, 5.2-8.6 micrograms per cubic
meter of diesel particulate from light-duty vehicles would occur at
this location over a 24-hour period. It should be noted that
parallel wind conditions were used to arrive at this estimation (a
condition which maximizes on-expressway concentrations but mini-
mizes the off-roadway levels).
Concentrations in the EPA CAMP-site study2/ were based on CO
monitoring data. Annual geometric mean values for the 7 cities
studied ranged from 4.8-8.0 micrograms per cubic meter for Wash-
ington, D.C. to 17.0-28.4 micrograms per cubic meter in Chicago. A
further description of monitoring sites of this study are in Table
A-10.
Upon reviewing all the studies, the localized impact off an
expressway and in a street canyon was best evaluated by the
Aerospace report as their methodology avoided 'such assumptions as
constant wind velocity and atmospheric stability. On the express-
way, SwRI was most thorough in their evaluation, basing such
parameters as wind speed and direction and traffic counts on real
world data. The CAMP-site study is also noteworthy because the
data base (CO monitors at CAMP-sites in 7 major U.S. cities) was
obtained over a long period of time, thus adding validity to the
predictions obtained.
-------
. REFERENCES
JY EPA memorandum from George J. Schewe, Model Application
Section, to Joseph H. Sommers, Office of Mobile Source Air
Pollution Control, "Reply to Request for Concentration
Estimates near Roadways Due to Mobile Source Emissions of
Sulfuric Acid and Diesel Particulates (TSP and BaP)," April
12, 1979.
2J EPA memorandum from Richard A. Rykowski, SDSB, to Robert
E. Maxwell, Chief, SDSB, "Related Impact of CO and Partic-
ulate on Urban Air Quality," November, 1979.
3J "Study of Particulate Emissions from Motor Vehicles - A Report
to Congress," Rough Draft, Southwest Research Institute, San
Antonio, Texas.
4/ "General Motors Response to EPA Notice of Proposed Rulemaking
on Particulate Regulation for Light-Duty Diesel Vehicles,"
General Motors Corporation, April 19, 1979.
5J "Toyota Comment on the EPA Proposed Particulate Regulation for
Light-Duty Diesel Vehicles," Toyota Motor Co., April, 1979.
6/ "Assessment of Environmental Impacts of Light-Duty Vehicle
Dieselization," Rough Draft, The Aerospace Corporation,
Prepared for U.S. Department of Transportation, Contract
#DOT-TSC-1530.
7/ Zimmerman, J.R. and R.S. Thompson, "User's Guide for HIWAY, a
~ Highway Air Pollution Model," EPA-650/4-74-008, Research
Triangle Park, N.C., 1975.
8/ "Final Manual, Special Area Analysis," ( SAPPOLUT), U.S.
Department of Transportation, Washington, D.C., August,
1973.
9_/ Patterson, R.M. and F.A. Record, "Monitoring and Analysis of
Carbon Monoxide and Traffic Characteristics at Oakbrook,"
EPA-450/3-74-058, Research Triangle Park, N.C. 27711.
10/ "Air Quality Assessment of Particulate Emissions from Diesel
Powered Vehicles," PEDCo Environmental, Inc., Cincinnati,
Ohio, March, 1978.
ll/ "Guidelines for Air Quality Maintenance Planning and Analysis,
Volume 9 (Revised): . Evaluating Indirect Sources," EPA-450/
4-78-001, OAQPS No. 1.2-028R, Research Triangle Park, N.C.,
September 1978.
-------
12/ Chock, David P., "A Simple Line-Source Model for Dispersion
Near Roadways," Atmospheric Environment, Vol. 12, pp 823-829.
13/ Sievers, H.E., "Modified Line Source Models for Predicting 24
Hour and Annual Particulate Concentrations Resulting from
Reentrainment of Roadway Dust," APCA Paper No. 78-146,
Houston, June, 1978.
14/ Johnson, W.B., F.L. Ludwig, W.F. Dabberdt, and R.J. Allen, "An
Urban Diffusion Simulation Model for Carbon Monoxide," JAPCA
23(b): 490-498, 1973.
15/ "Draft Regulatory Analysis: Light-Duty Diesel Particulate
Regulations," EPA, December 22, 1978.
16/ U.S. Department HEW (1970), "Air Quality Criteria for Carbon
Monoxide," Washington, D.C., p. 6-6.
17/ S.H. Cadle, et al, "Results of the General Motors Sulfate
Dispersion Experiment," GMR-2107, General Motors Corporation,
Warren, Michigan, March 18, 1976.
18/ W.F. Dabberdt, "Experimental Studies of Near-Roadway Disper-
sion," Presented at the 69th APCA Annual Meeting, Portland,
Oregon, June 27 to July 1, 1976.
19/ Hourly Data, SRI Project 2761, Printout of Tape Data Received
from Federal Highway Administration, Washington, D.C.
20/ L.J. Habegger, et al, "Dispersion Simulation Techniques for
Assessing the Air Pollution Impacts of Ground Transportation
Systems," Report ANL/ES-29, Argonne National Laboratory,
Argonne, Illinois, April, 1974.
21/ W.A. Carpenter, et al, "Supportive Data and Methods for the
Evaluation of AIRPOL-4," Report VH TRC 75-R57, Virginia
Highway and Transportation Research Council, Charlottesville,
Virginia, May, 1975.
22/ Summary Data Tape of SRI St. Louis Street Canyon Experiment,
Obtained from National Climatic Center, Ashville, North
Carolina.
23/ Summary Data Tape of SRI San Jose Street Canyo.n Experiment,
Obtained from National Climatic Center, Ashville, North
Carolina.
24/ F.A. Brunner, "Atmospheric Dispersion of Vehicular Emissions
in an Urban Street Canyon," Ph.D. Thesis, Vanderbilt Univer-
sity, Nashville, Tennessee, 1971.
-------
25/ G.L. Latshaw, et al, "Microscale CO Concentrations and Wind
Characteristics on New York City Streets," p. 195 of Assessing
Transportation-Related Air Quality Impacts, Conference of
October 22-24, 1975, Washington, D.C., Sponsored by U.S. DOT
and EPA.
26/ "Dispersion of Pollutants Near Highways, Data Analysis and
Model Evaluation," EPA-600/4-79-011, Environmental Sciences
Research Laboratory, Research Triangle Park, N.C., February
1979.
-------
Appendix
-------
Table A-l
Vehicle Distribution and Roadway Split in
Percentage by Hour of Day for a Suburban Freeway
HOUR
0
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Source :
PERCENT ADT
1.5
1.0
0.5
0.5
1.0
1.5
4.5
8.5
6.5
5.0
5.0
4.5
4.5
4.5
5.5
7.0
8.5
8.5
5.5
4.5
3.5
3.0
2.5
2.5
SAPPOLUT8/
PERCENT IN-BOUND
44
46
48
54
60
68
68
64
58
54
52
50
50
52
52
48
42
40
44
48
48
44
46
44
PERCENT OUT-BOUND
56
54
52
46
40
32
32
36
42
46
48
50
50
48
48
52
58
60
56
52
52
56
54
56
Taken from Reference I/.
-------
Table A-2
Particulate Emission Rate (by class) I/
Vehicle Class* Particulates (gm/mi)
LDV-G 0.0087
LDT-G 0.0087
HDV-G 0.029
LDV-D 0.9
LDT-D 0.9
HDV-D Low 2.0 High 3.0
Vehicle-type Split by Fraction of Urban VMT J7
Best Estimate . . Max Estimate
LDV-G
LDT-G
HDV-G
LDV-D
LDT-D
HDV-D
0.754
0.098
0.025
0.076
0.010
0.037
0.639
0.084
0.010
0.191
0.024
0.052
*Key: LD = Light-Duty
HD = Heavy-Duty
V = Vehicle
T = Truck
-G = Gasoline-fueled
-D = Diesel-fueled
-------
TABLE A-3 Light Duty Diesel E/nlsslon Factors by Engine Model
Emission Factors, q/km
Ycar(s)
Thru 1980
'81-'82 controlled
'81-'82 not controlled
'83 & later controlled
'83 & later not controlled
M-B
2000 J
2000 2400
0.38 0.28
- 0.28
- 0.28
- 0.12
0.28
3000,
300SD,
300CD
0.36
0.36
0.36
0.12
0.36
GM
Pengeot
5040
0.26
0.26
0.26
0.12
0.26
VW
Rabbit
0.18
0.18
0.18
0.12
0.18
JH
Scout
0.24
0.24
0.24
0.12
0.24
Chrysler
Mitsubishi
0.38
0.37
0.38
0.12
0.38
350
0.55
0.37
0.55
0.12
0.55
350
pickup
0.38
0.37
0.28
0.12
0.38
260
0.56
0.37
0.56
0.12
0.56
projected
V6
. 0.35
0.35
0.35
0.12
0.35
projected
14
....
0.27
0.27
0.12
0.37
Source: Reference 3/
-------
TABLE A-A Percent of Tota'1 Diesel Sales for Various Models
Percent of Diesel Sales
H-B
Yoar(s)
3000,
200D J 300SD, Pcngoot . VW
2000 240D 300CD
1973 & earlier
1974
1975
197G
1977
1978
1979
1980
1981
1982
1983 '
1984
1985
100
100
90
33
28
4
2
2
. 1
1
1
1
1
46
32
13
7
4
3
3
3
2
2
10
17
14
3
2
1
1
1
1
1
1
GH
IH Chrysler 350 projected projected
504D_ Rabbit Scout Mitsubishi 350 pickup 260 VG 14
22
18
31
21
16
14
12
12
10
44
33
27
21
18
16
15
13
17
9
6
5
4
3
3
3
14
13
10
8
8
7
7
24
29
31
32
31
32
13
19
23
27
30
Source: Reference 3/
-------
'TABLE A-5 Exhaust Partkulate Emission Factors for a Crowded Expressway by Model Year
With DioseT Participate Regulations
Participate Emissions g/km .
Model Year <69 70 71 72 73 74 75 76 77 70 79 00 01 02 03 04 05 06 07 03 09 90 91 >92
for 1905 estimates
Light-duty gasoline 0.11 0.06 0.06 0.06 0.06 0.06 0.04 0.04 0.03 0.03 0.03 0.03 0.01 0.01 0.01 0.01 0.01
Light-duty dlcsel 0.27 0.27 0.27 0.27 0.27 0.25 0.23 0.22 0.22 0.26 0.27 0.27 0.22 0.22 0.00 0.03 0.00
Medium-duty truck 0.31 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.17 0.17 0.17 0.23 0.23 0.23 0.27
Heavy-duty gasoline 0.52 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.24 0.24 0.24 0.24 0.04 0.04 0.04
Heavy-duty dfesel 1.31 1.12 1.12 1.12 1.12 0.99 0.99 0.99 0.99 0.99 0.99 Q.99 0.99 0.99 0.01 0.01 0.01
Motorcycles 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.02 0.02 0.02 .006 .006 .006
for 1990 and 2000 estimates {assumes no leaded gasoline)
Light -duty gasoline 0.06 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01
Light-duty dlesel 0.27 0.27 0.27 0.27 0.27 0.25 0.23 0.22 0.22 0.26 0.27 0.27 0.22 0.22 0.00 0,00 0.08 0.00 0.08 0.00 0.00 0.00 0.00 0.08
Medium-duty truck 0.16 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.13 0.13 0.13 0.19 0.19 0.19 0.22 0.19 0.19 0.19 0.24 0.24 0.24 0.20
Heavy-duty gasoline 0.25 0.22 0.22 0.22 0.22 0.22 0.22 0.22 0.22 0.22 0,12 0.12 0.12 0.12 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04
Heavy-duty diesel 1.31 1.12 1.12 1.12 1.12 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.01 0.81 6.01 0.62 0.62 0.62 0.62 0.62 0.62 0.62
Motorcycles 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.01 0.01 0.01 .003 .003 .003 .003 .003 .003 .003 .003 .003 .003
Source: Reference 3/ "
-------
1 TABLE A-6 Exhaust Partlculatc Emission Factors for a Crowded Expressway by Model Year
Without Diesel Participate Regulations
Participate Emissions g/km
Model Year <69 70 71 72 73 74 75 76- 77 70 79 CO 01 02 83 84 85 06 87 CO 09 90 91 >92
for 1985 estimates .
Light-duty gasoline 0.11 0.06 0.06 0.06 0.06 0.06 0.01 0.04 0.03 0.03 0.03 0.03 0.01 0.01 0.01 0.01 0.01
/
Light-duty dlesel 0.27 0.27 0.27 0.27 0.27 0.25 0.23 0.22 0.22 0.26 0.27 0.27 0.26 0.25 0.25 0.25 0.24 ''
Medium-duty truck 0.31 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.17 0.17 0.17 0.23 0.24 0.26 0.20
Heavy-duty gasoline 0.52 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.24 0.24 0.24 0.24 0.04 0.04 0.04
Heavy-duty dicsel 1.31 1.12 1.12.1.12 1.12 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99
Motorcycles 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.02 0.02 0.02 .006 .006 .006
for 1990 and 2000 estimates (assumes no leaded gasoline)
Light-duty gasoline 0.06 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01
Light-duty dlesel 0.27 0.27 0.27 0.27 0.27 0.25 0.23 0.22 0.22 0.26 0.27 0.27 0.26 0.25 0.25 0.25 0.24 0.24 0.24 0.24 0.24 0.24 0.24 0.24
Medium-duty truck 0.16 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.13 0.13 0.13 0.19 0.22 0.26 0.26 0.32 0.32 0.32 0.30 0.30 0.30 0.44
Heavy-duty gasoline 0.25 0.22 0.22 0.22 0.22 0.22 0.22 0.22 0.22 O.S2JJ..12 0.12 0.12 0.12 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04
Heavy-duty dlesel 1.31 1.12 1.12 1.12 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99
Motorcycles ' 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.01 0.01 0.01 .003 .003 .003 .003 .003 .003 .003 .003 .003 .003
Source: Reference 3/
-------
Table A-7
Comparison of On-Freeway Emission
Factors for Houston, Texas
Diesel Particulate
Regulations
Composite Emission Factor g/mile
Low est. of
dieselization
Best est. of
dieselization
0.204
High est.
dieselization
1985
1985
yes
no
0.150
0.162
0.151
0.167
0.152
0.169
1990
1990
yes
no
0.123
0.162
0.130
0.183
0.136
0.205
2000
2000
yes
no
0.125
0.185
0.140
0.236
0.161
0.305
Source: Reference 3/.
-------
Organization
GM1/
SRI2/
SRI
ANL3/
ANL
Table A-8
Urban Freeway Data Base
Roadway Characteristics
Date of Measure-
Measure- merits per
ments Receptor
Sept-Oct 66
1975
Jan-Feb 45
1975
Aug-Sept 47
1975
June-July 49
1973
Location
GM Proving
Ground,
Milford.Mi.
Highway
101 near
Santa Clara,
Ca.
1-280 in
San Jose,
Ca.
1-55 in
suburbs of
Chicago,
111.
Type
at-grade
at-grade
above-grade
(elevated on
columns, not
a solid fill)
at-grade
Emissions
Surrounding from Vehicles
Terrain not on Roadway
nearly level . no
lightly wooded
rural
level ,open no
urban streets yes
and low
buildings
(near CBD)
level, open no
Species
Measured
sulf ate
part iculate;
tracer gas
(SF6)
CO; tracer
gases (SF6
and Freon)
CO; tracer
gases (SFfc
and Freon)
CO
Reference
17
18
19.
19
20
Aug 1973
31
1-90, in be low-grade
suburbs of
Chicago,
111.
level, resi-
dential
" not
significant"
CO
20
-------
Table A-8 (cont.)
Urban Freeway Data Base
Organ i zation
VH TRC4/
VH TRC
Roadway Characteristics
Date of Measure-
Measure- merits per
i ments Receptor
June 1973 21
- July 1974 .
Jan-Aug 15
1974
Location Type
1-495, in at-grade
Fairfax
County, Va.
1-64, in at-grade
Norfolk,
Va.
Emissions
Surrounding from Vehicles Species
Terrain not on Roadway Measured
level rural No CO
uncomplicated No CO
scattered 1-
story residen-
Reference
21
21
tial
Source: Reference 6/
I/ Gener.nl. Motors Corporation
Y/ SRI International
_3_/ Argonne National Laboratory
4/ Virginia Highway & Transporation Research Council
-------
Table A-9
Composite Emission Factors for Urban Freeway and
Street Canyon Analyses
LDV
Dieselization
Rate
B/C
(1%)
10%
25%
25% + 100%
Taxis
Projection
Year -
1975
1985
1990
2000
1985
1990
2000
1985
1990
2000
1985
1990
2000
Diesel Exhaust
Particulates
(g/mif
0.0425
0.0680
0.0941
0. 146
0.0859
0.115
0.167
0.118
0.151
0.201
0.192
0.192
0.234
Total Exhaust
Particulates
(g/mi)*
0.301
0.133
0.137
0.163
0.151
0.157
0.183
0.181
0.190
0.215
0.256
0.231
0.248
'Based on total VMT, all vehicle classes.
Source: Reference 6/
-------
Table A-10
Informt Ion CnnccrrMnr. CO Prnhnii nt CAMP, s.t ten, 'if
\
ICA.VP "iro
1
lCh.le.-ico
1
1
1
1
1
(Cincinnati
1
1
!'\.avcr
1
ll'iiil.idelphia
1
ISt. Louis
1
|San I'ronciaco
I'
!
1
1'iV.ii.hlnston,-
! D.C.
1
I Hclflhc Above
Crounri, Meter (ft.)
.'..12
1 (13.5)
4.57
(15)
5.13
(17)
4.57
(15)
';.57
(15)
1.33 above ground
(6)
3.66 above otrcct
(12)
3.36
(H)
Distance froa Nearest
Lnrp.e Rond, Meter (ft.)
6.94
(22.75)
6.1
(20)
6.41
(21)
61 frcu ?.0ch st.
(200) nnd 21ct ot.
12.2
(40)
3.05
(10)
15.25
(50)
Vehicle Count
(vohiclcn/dny)
.
46,000
8,550
17,000
10,578 (20th ot.)
. 3,576 (21st nt.)
17,950
'
14,740
Comr.onta
liuatdity not compensated - eny enhance
to twice ns mucl)
Enct on Concrcao - 22,000 vrhlclrs
. J.iy
Wont on Conercna - 24,000 vohlclrn
.l.v/
30.5 r.otcr (100 ft.) to the north la
Lincoln Pkwy, 9643 cnro/d.iy. Ccntrnl
PVv»y to the c.intj 10j570 vrhlc 1 c^/'lny .
'
9.15 Q (30 ft.) fron parking lot of
193 flpncon - nid Dec. to ntd Feb.
-------
Table A-11
Traffic Characterization 2/
Vehicle Class
CO Emission
Factor (g/mile)-
1967
Part iculate
Emission Factor
(g/mile)
LDV
89
0.5
LDT
91
0.5
HDV-G
298
HDV-D
35
2.0
Fraction of
Urban VMT
1974
1990
0.83
0.83
0.108
0.108
0.036
0.025
0.026
0.037
Diesel Fraction -
1990
0.1
0.1
1.0
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