United States Air and Radiation EPA420-P-99-011
Environmental Protection April 1999
Agency M6.FLT.007
vvEPA Fleet Characterization
Data for MOBILE6:
Development and Use of
Age Distributions,
Average Annual Mileage
Accumulation Rates and
Projected Vehicle Counts
for Use in MOBILE6
> Printed on Recycled Paper
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EPA420-P-99-011
April 1999
for
for in
M6.FLT.007
Trade Jackson
Assessment and Modeling Division
Office of Mobile Sources
U.S. Environmental Protection Agency
NOTICE
This technical, report does not necessarily represent final EPA decisions or positions.
It is intended to present technical 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.
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EPA420-P-99-011
- DRAFT -
Fleet Characterization Data for MOBILE6:
Development and Use of Age Distributions,
Average Annual Mileage Accumulation Rates, and
Projected Vehicle Counts for Use in MOBILE6
Report Number M6.FLT.007
March 18,1999
Tracie R. Jackson
Assessment and Modeling Division
U.S. EPA Office of Mobile Sources
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TABLE OF CONTENTS
ABSTRACT 3
1.0 Introduction 4
2.0 Development of U.S. Fleet Registration Distribution by Age 7
3.0 Development of Average Annual Mileage Accumulation Rates by Age 15
4.0 Vehicle Counts for VMT Weighting Calculations 18
4.1 Methodology for Estimating Vehicle Counts for Calendar Years 1996
through 2050 18
4.1.1 Light-duty Vehicle Counts for 1996 through 2050 19
4.1.2 Heavy-duty Vehicle Counts for 1996 through 2050 26
4.2. Gasoline/Diesel Fuel Ratios 31
4.3 Interpolating Between MOBILES and MOBILE6 Vehicle Counts 35
5.0 Integration of Registration Distribution by Age, Average Annual Mileage
Accumulation Rates by Age, and Future Vehicle Count Data in MOBILE6 36
5.1 Expansion of Vehicle Categories 36
5.2 Use of Registration Distribution by Age and Average Annual Mileage
Accumulation by Age in MOBILE6 38
APPENDIX A: Motorcycle Age Distribution, Mileage Accumulation Rates, and Vehicle
Counts 40
APPENDIX B: Vehicles in Operation, Raw Mileage Accumulation Rate, and Curve Fitting
Equations from the Arcadis Report 42
APPENDIX C: Federal Definitions for Light-duty Vehicles 46
APPENDIX D: Complete Tables of Vehicle Counts, pre!982-2050 48
REFERENCES 51
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ABSTRACT
The MOBILE model requires estimates of a distribution of registered vehicles by age,
average annual mileage accumulation rates by age and vehicle category, and estimates of the
projected size of the fleet in future years. While this type of information exists in the current
version of the model, MOBILES, the data contained in that model is outdated. Therefore it was
necessary to develop new estimates for use in the new version of the model MOBILE6. The new
estimates are largely based on work done by Arcadis, Geraghty & Miller in a report entitled
"Update of Fleet Characterization Data for Use in MOBILE6." The Arcadis report describes the
number of vehicles registered by age and class and the average mileage accumulation rates on
July 1, 1996. The following report describes the methodology EPA used to convert the July 1,
1996 registration profile into a generally-applicable registration distribution by age, the use of the
average annual mileage accumulation rates, and the methodology for projecting the size of future
vehicle fleets by vehicle category. The report also describes how the results of this analysis will
be applied in the model.
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1.0 Introduction
The United States Environmental Protection Agency's (USEPA) Highway Vehicle
Emissions Modeling Team is currently developing an updated version of its on-highway
emission factor model, known as MOBILE6. To estimate emission rates of hydrocarbons,
carbon monoxide, and oxides of nitrogen from the U.S. motor vehicle population, the model
requires data that characterizes the size, composition and driving attributes of current and future
vehicle fleets. As part of its effort to obtain this data, EPA contracted with Arcadis, Geraghty &
Miller to analyze the most up-to-date sources of data describing the number of vehicles registered
in the United States and the average mileage these vehicles drive annually. The results of this
analysis are detailed in EPA report # EPA420-P-98-016, entitled "Update of Fleet
Characterization Data for Use in MOBILE6."1 This report, hereafter referred to as the "Arcadis
Report," may be found on the World Wide Web at http://www.epa.gov/OMSWWW/m6.htm under
document number M6.FLT.002.
The Arcadis report provides an estimate of the number of vehicles of various ages in
operation in the United States as of July 1, 1996, as well as the average annual mileage
accumulation rate per vehicle, for gasoline- and diesel-fueled cars, trucks and buses.. Due to
limitations in the data sources used to develop their analysis, Arcadis, Geraghty & Miller
grouped several GVWR classes together, thus providing only eighteen different vehicle
categories. These categories are listed in Table 1, and are defined based on EPA-specified gross-
vehicle weight ratings (GVWR), fuel type and vehicle type.
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Table 1. Eighteen Vehicle Class Categories as Defined in Arcadis Report
Designation
LDGV
LDDV
LDGT (0-6,000 Ibs)
LDGT (6,00 1-8,500)
LDDT (0-6,000 Ibs)
LDDT (6,00 1-8,500)
HDGV (classes 2B-3)
HDGV (classes 4-8)
HDDV(class 2B)
HDDV(class 3)
HDDV(class 4-5)
HDDV(class 6-7)
HDDV(class 8A)
HDDV(class 8B)
HDGB (school)
HDGB (transit)
HDDB (school)
HDDB (transit)
Description
Light-duty gasoline vehicles
Light-duty diesel vehicles
Light-duty gasoline trucks
Light-duty gasoline trucks
Light-duty diesel trucks
Light-duty diesel trucks
Heavy-duty gasoline vehicles
Heavy-duty gasoline vehicles
Light heavy-duty diesel trucks
Light heavy-duty diesel trucks
Light heavy-duty diesel trucks
Medium heavy-duty diesel trucks
Heavy heavy-duty diesel trucks
Heavy heavy-duty diesel trucks
Heavy-duty gasoline school buses
Heavy-duty gasoline transit buses
Heavy-duty diesel school buses
Heavy-duty diesel transit buses
Gross Vehicle Weight
(Ibs)
0-6000
0-6000
<6000
6001-8500
<6000
6001-8500
8500-14000
>14000
8501-10000
10001-14000
14001-19500
19500-33000
33000-60000
>60000
all
all
all
all
The MOBILE6 model requires a fractional distribution of vehicles by age and average
annual mileage accumulation rates for each vehicle, ages 1 through 30, to determine the fraction
of travel attributed to each age of vehicle. MOBILE6 also requires projections of future vehicle
fleet size. This information is required for thirty separate vehicle categories, as listed in Table 2.
These modeling requirements necessitated further EPA analysis, using the results of the Arcadis
report as a starting point. Hence, the following report documents how EPA will use the results of
the Arcadis, Geraghty & Miller fleet characteristic analysis in MOBILE6. The current document
describes the methodology used to develop a general vehicle registration distribution by age,
reproduces the results of the Arcadis analysis of average annual mileage accumulation rates by
age, the development of projected vehicle population estimates, and the application of these
analyses in MOBILE6.
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Table 2. MOBILE6 Vehicle Categories
Gasoline Vehicle Categories
Light-duty gasoline vehicle
Light-duty gasoline truck 1
Light-duty gasoline truck 2
Light-duty gasoline truck 3
Light-duty gasoline truck 4
Heavy-duty gasoline vehicle class 2B
Heavy-duty gasoline vehicle class 3
Heavy-duty gasoline vehicle class 4
Heavy-duty gasoline vehicle class 5
Heavy-duty gasoline vehicle class 6
Heavy-duty gasoline vehicle class 7
Heavy-duty gasoline vehicle class 8A
Heavy-duty gasoline vehicle class 8B
Heavy-duty gasoline Bus *
Motorcycle
Diesel Vehicle Categories
=L
Light-duty diesel vehicle
Light-duty diesel truck 1
Light-duty diesel truck 2
Light-duty diesel truck 3
Light-duty diesel truck 4
Heavy-duty diesel vehicle class 2B
Heavy-duty diesel vehicle class 3
Heavy-duty diesel vehicle class 4
Heavy-duty diesel vehicle class 5
Heavy-duty diesel vehicle class 6
Heavy-duty diesel vehicle class 7
Heavy-duty diesel vehicle class 8A
Heavy-duty diesel vehicle class 8B
Heavy-duty diesel School Bus
Heavy-duty diesel Transit Bus
* Note: MOBILE6 will only contain one heavy-duty gasoline bus category; this category contains all heavy-duty
gasoline buses.
-6-
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2.0 Development of U.S. Fleet Registration Distribution by Age
The Arcadis report provides an estimate of the number of vehicles of various ages in
operation in the United States as of July 1, 1996 for eighteen GVWR-based vehicle categories,
which are listed in Table 1. These data were compiled using a vehicle registration database
purchased from the R.L. Polk Company, a widely recognized resource in the field of collection of
vehicular statistics. Several modifications to the Polk database were required to respond to
comments made by EPA experts on expected fleet composition; these modifications are detailed
in the Arcadis Report (M6.FLT.003, EPA420-P-98-016).
The data provided in the Arcadis report represent a "snapshot" in time, and, as such,
include the residual impacts of several historical events (which were economically, politically
and/or resource-driven) that have affected motor vehicles sales volumes. However, the MOBILE
model is used to describe the emissions effects incurred as a result of the vehicle fleet in future
years as well as past years. Therefore, use of this "snapshot" vehicle age-based registration
distribution to represent the fleet in any year other than 1996 would provide inaccurate results, as
there is no reason to expect that the economic and political factors which have resulted in the
1996 vehicle age-based registration distribution will occur in exactly the same way again.
In an effort to present a "generic" vehicle-registration distribution by age for modeling
purposes, and to mitigate the effects of these isolated events on the distribution of vehicles in the
in-use fleet, EPA has opted to fit curves through the 1996 snapshot data. Curves were fit through
the registration data for each vehicle class and fuel type category, as well as for aggregated
vehicle category combinations (e.g., all light-duty vehicles, all light-duty diesel vehicles, etc).
Several types of curves were explored (e.g., linear, polynomial, exponential, Weibull) in an effort
to find the best fit. Due to extreme variability in the distribution of the vehicle population in
1996, many of the fuel-type specific curves were deemed useless and discarded; it was the
conclusion of EPA staff that the best, most representative curves were those derived from the
following aggregate vehicle categories: light-duty vehicles (All), light-duty trucks (0- 6,000 Ibs
GVWR), light-duty trucks (6,001-8,500 Ibs GVWR), heavy-duty vehicles classes 2B-3 (8,501-
14,000 Ibs GVWR), heavy-duty vehicles classes 4-8 (14, 001 Ibs GVWR and greater), heavy-
duty school buses (All), and heavy-duty transit buses (All). To develop a general curve, in each
case, the current model year vehicle population data (1996) was removed from the sample
because it did not represent a full year, and a best fit analysis was performed on the remaining
population data. The best fit analyses resulted in age distribution estimates for vehicles ages 1
through 30 (where age is calendar year minus model year). However, since the vehicle sales year
begins in October, the estimated age 1 population was multiplied by 0.75 to account for the fact
that approximately 75% of the year's sales will have occurred by July 1st of a given calendar
year.
Exponential curve fitting was used for light-duty trucks 6,001-8,500 Ibs, heavy-duty
vehicles classes 2B-3, heavy-duty vehicles classes 4-8, and heavy-duty school buses. For light-
duty vehicles, light-duty trucks 0-6,000 Ibs, and heavy-duty transit buses, both Weibull curve
-7-
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fitting and exponential curve fitting were used to create the final age distributions. The nature of
the Weibull curve fitting formula is to produce an "S" shaped curve, which is relatively flat for
the first third of the data, decreases rapidly for the next third, and flattens again for the final third.
While using this formula resulted in a better overall fit for the light-duty vehicle, light-duty truck
0-6,000 Ibs, and heavy-duty transit bus categories, the flatness of the final third for each curve
resulted in unrealistically low vehicle populations for the older vehicle ages. For this reason, the
original Weibull curve was used where it fit best, and exponential curves were fit through the
data at the age where the Weibull curves began to flatten. Table 3 presents the equations used to
create the age distribution, and the years in which the equations were used. Note that MOBILE6
will use the MOBILES age distribution for motorcycles; this age distribution is presented in
Appendix A.
Table 3. Curve Fit Equations for Registration Distribution by Age
Aggregate Vehicle Category
Light-duty vehicle
Light-duty truck 0-6,000 Ibs
Light-duty trucks 6,001-8,500 Ibs
Heavy-duty vehicles classes 2B-3
Heavy-duty vehicles classes 4-8
Heavy-duty school buses
Heavy-duty transit buses
Equation
v= 0 92867417 (-(age/16-10050554) ex? (4-45489164)
y=112855609.5568(-a2321*age
y= o 90942551 (-(age/14-38211814)exp(3-04037069)
y = 805298.7399(-ao409*age)
y = 1305324 4(-°-070863*age)
y = 732326.5(-ao9455*age)
y = 404143. 88(-ao66843*age)
Y = 3g9g2(-°-068092*age)
y= o 73096392 (-(age/17-16909475)exp(12-53214119)
y = 24987.0776(-a2000*age)
Vehicle
Ages
1-12
13-30
1-18
19-30
1-30
1-30
1-30
1-30
1-17
18-30
Table 4 lists the vehicle populations by age that were derived from curve fitting the
original July 1, 1996 "snapshot" data. Table 5 presents this data converted to distributions of
registration fractions by age for each of the seven vehicle categories that were chosen for use in
the model. Figures 1 through 7 display the curve fits associated with these distributions. These
distributions will be used for the vehicle subclasses that fall into these larger groups, as described
in Section 5.2.
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Table 4. U.S. Vehicles in Operation—Results of Curve Fitting for Selected Vehicle
Categories as of July 1.
Vehicle
Age
1*
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
LDV
All
6,388,406
8,517,125
8,513,130
8,500,705
8,471,497
8,413,702
8,312,078
8,148,449
7,902,918
7,556,020
7,091,945
6,502,671
5,522,382
4,378,513
3,471,578
2,752,499
2,182,365
1,730,325
1,371,917
1,087,748
862,439
683,799
542,162
429,862
340,823
270,228
214,254
169,875
134,688
106,790
LDT
0-6,000
2,539,245
3,378,282
3,357,951
3,318,193
3,253,029
3,157,436
3,027,857
2,862,713
2,662,837
2,431,716
2,175,488
1,902,590
1,623,100
1,347,783
1,086,999
849,631
642,213
468,411
370,226
355,389
341,147
327,476
314,352
301,754
289,662
278,053
266,910
256,214
245,946
236,090
LDT
6,001-8,500
912,020
1,132,838
1,055,340
983,143
915,886
853,230
794,860
740,483
689,826
642,635
598,672
557,717
519,563
484,019
450,907
420,061
391,324
364,553
339,614
316,381
294,737
274,574
255,790
238,292
221,990
206,803
192,656
179,476
167,198
155,760
HDV
2B-3
8,501-14,000
499,694
606,149
551,464
501,712
456,449
415,269
377,804
343,720
312,710
284,498
258,831
235,480
214,236
194,908
177,324
161,326
146,771
133,530
121,483
110,523
100,552
91,481
83,227
75,719
68,888
62,673
57,019
51,874
47,194
42,937
HDV
4-8B
14,001+
283,511
353,571
330,710
309,327
289,327
270,619
253,122
236,755
221,447
207,129
193,736
181,210
169,493
158,534
148,283
138,696
129,728
121,340
113,494
106,156
99,292
92,872
86,867
81,251
75,997
71,083
66,487
62,188
58,167
54,406
HD
School
Bus(All)
27,312
34,019
31,780
29,688
27,733
25,908
24,203
22,609
21,121
19,731
18,432
17,219
16,085
15,026
14,037
13,113
12,250
11,444
10,690
9,987
9,329
8,715
8,142
7,606
7,105
6,637
6,200
5,792
5,411
5,055
HD
Transit
Bus(All)
2,597
3,463
3,463
3,463
3,463
3,463
3,463
3,462
3,462
3,459
3,450
3,424
3,358
3,204
2,881
2,291
1,431
683
559
458
375
307
251
206
168
138
113
92
76
62
LDV
LDT
HDV (2B-3)
HDV (4-8B)
HD Sch. Bus
HD Iran. Bus
Light-duty vehicle
Light-duty truck
Heavy-duty vehicles 8,500-14,000 Ibs GVWR
Heavy-duty vehicles greater than 14,000 Ibs GVWR
Heavy-duty school buses
Heavy-duty transit buses
Age 1 = 75% of Age 1 as predicted by the curve fit analysis to reflect a July 1 population of age 1 vehicles
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Table 5. U.S. Vehicle Fleet Distribution of Registration Fractions by Age for Selected
Vehicle Categories as of July 1.
Vehicle
Age
1*
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Total
LDV
ALL
0.053
0.071
0.071
0.071
0.070
0.070
0.069
0.068
0.066
0.063
0.059
0.054
0.046
0.036
0.029
0.023
0.018
0.014
0.011
0.009
0.007
0.006
0.004
0.004
0.003
0.002
0.002
0.001
0.001
0.001
1.000
LDT
0 -6,000
0.058
0.077
0.077
0.076
0.074
0.072
0.069
0.066
0.061
0.056
0.050
0.044
0.037
0.031
0.025
0.019
0.015
0.011
0.008
0.008
0.008
0.007
0.007
0.007
0.007
0.006
0.006
0.006
0.006
0.005
1.000
LDT
6,001-8,500
0.059
0.074
0.069
0.064
0.060
0.056
0.052
0.048
0.045
0.042
0.039
0.036
0.034
0.032
0.029
0.027
0.025
0.024
0.022
0.021
0.019
0.018
0.017
0.016
0.014
0.013
0.013
0.012
0.011
0.010
1.000
HDV2B-3
8,501-14,000
0.074
0.089
0.081
0.074
0.067
0.061
0.056
0.051
0.046
0.042
0.038
0.035
0.032
0.029
0.026
0.024
0.022
0.020
0.018
0.016
0.015
0.013
0.012
0.011
0.010
0.009
0.008
0.008
0.007
0.006
1.000
HDV 4-8B
14,001+
0.057
0.071
0.067
0.062
0.058
0.055
0.051
0.048
0.045
0.042
0.039
0.036
0.034
0.032
0.030
0.028
0.026
0.024
0.023
0.021
0.020
0.019
0.017
0.016
0.015
0.014
0.013
0.013
0.012
0.011
1.000
HD
School
Bus
(All)
0.058
0.072
0.067
0.063
0.059
0.055
0.051
0.048
0.045
0.042
0.039
0.036
0.034
0.032
0.030
0.028
0.026
0.024
0.023
0.021
0.020
0.018
0.017
0.016
0.015
0.014
0.013
0.012
0.011
0.011
1.000
HD
Transit.
Bus
(All)
0.045
0.060
0.060
0.060
0.060
0.060
0.060
0.060
0.060
0.060
0.060
0.060
0.059
0.056
0.050
0.040
0.025
0.012
0.010
0.008
0.007
0.005
0.004
0.004
0.003
0.002
0.002
0.002
0.001
0.001
1.000
LDV
LDT
HDV (2B-3)
HDV (4-8B)
HD Sch. Bus
HD Iran. Bus
Light-duty vehicle
Light-duty truck
Heavy-duty vehicles 8,500-14,000 Ibs GVWR
Heavy-duty vehicles greater than 14,000 Ibs GVWR
Heavy-duty school buses
Heavy-duty transit buses
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75
1
pre
the
ana
refl
1
of
veh
Figure 1. July 1,1996 Age Distribution Curve Fit For Light-
duty Vehicles
(Comparison of Arcadis In-Use Data to Curve Fit)
0.080
10 15 20
Vehicle Age
25
30
-Original LDV Age Distribution
-New LDV Curve Fit Distribution
Age 1 =
% of Age
as
dieted by
curve fit
lysis to
ect a July
population
age 1
icles
Figure 2. July 1,1996 Age Distribution Curve Fit for Light-duty
Trucks 0-6,000 Ibs
(Comparison of Arcadis In-Use Data to Curve Fit)
0.090
10 15 20
Vehicle Age
25
30
-Original LOT 0-6,000 Ibs Age Distribution
-New LOT 0-6,000 Ibs Curve Fit Distribution
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Figure 3. July 1,1996 Age Distribution Curve Fit for
Light-duty Trucks 6,001-8,500 Ibs.
(Comparison of Arcadis In-Use Data to Curve Fit)
10 15 20
Vehicle Age
25
30
- Original LOT 6,000-8,500 Ibs Age Distribution
- New LOT 6,000-8,500 Ibs Curve Fit Distribution
0.120
Figure 4. July 1,1996 Age Distribution Curve Fit for
Heavy-duty Vehicle Classes 2B-3
(Comparison of Arcadis In-Use Data to Curve Fit)
10 15 20
Vehicle Age
30
- Original HDV2B-3 Age Distribution —•— New HDV2B-3 Curve Fit Distribution
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Figure 5. July 1,1996 Age Distribution Curve Fit for
Heavy-duty Vehicle Classes 4-8B
(Comparison of Arcadis In-Use Data to Curve Fit)
0.090
10
15 20
Vehicle Age
25
30
- Original HDV4-8B Age Distribution
-New HDV 4-8B Curve Fit Distribution
Figure 6. July 1,1996 Age Distribution Curve Fit for
School Buses
(Comparison of Arcadis In-use Data to Curve Fit)
0.100
0.000
-Original School Bus Age Distribution
-New School Bus Curve Fit FJistribution
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Figure 7. July 1,1996 Age Distrubution Curve Fit for
Transit Buses
(Comparison of Arcadis In-Use Data to Curve Fit)
0.090
•Original Transit Bus Age Distribution
•New Transit Bus Curve Fit Distribution
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3.0 Development of Average Annual Mileage Accumulation Rates by Age
The Arcadis report provides estimated average annual mileage accumulation rates for 18
vehicle categories. The non-bus estimates were generated from data contained in two travel
behavior surveys, namely the Department of Transportation's "1995 Nationwide Personal
Transportation Survey" for light duty vehicles and the U.S. Bureau of the Census' "1992 Truck
Inventory and Use Survey." Mileage data for school buses and transit buses were obtained from
Bobit Publication's "School Bus Fleet 1997 Fact Book Issue" and a data file provided by the
Federal Transportation Administration. Arcadis evaluated the data from these sources on a line-
by-line basis, eliminating any data records that were incomplete. Those records that were
retained were entered into a database, sorted into gross vehicle weight rating categories, plotted
graphically and the results were smoothed using linear and exponential best fit curve analyses.
The raw data and the equations for the curves are listed in Appendix B. A detailed explanation
of the analysis methods used to obtain average annual mileage accumulation rates can be found
in the Arcadis Report.
The curve-fit average annual mileage accumulation rates presented in the report are
reproduced here in Table 6. These age-specific average annual mileage accumulation rates
represent an the 1996 calendar year; in MOBILE6, these default rates will be applied to
appropriate vehicle categories as specified in Section 5.2, and will be used for all past, present
and future calendar years unless the model user provides their own data. Note that motorcycle
mileage accumulation rates are from MOBILES; these are listed in Appendix A.
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Table 6. Average Annual Mileage Accumulation (Curve Fit Data)
U.S. Levels
(12 months estimate)
Vehicle
Age
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
LDV
LDGV
14910
14174
13475
12810
12178
11577
11006
10463
9947
9456
8989
8546
8124
7723
7342
6980
6636
6308
5997
5701
5420
5152
4898
4656
4427
4208
4001
3803
3616
3437
LDDV
14910
14174
13475
12810
12178
11577
11006
10463
9947
9456
8989
8546
8124
7723
7342
6980
6636
6308
5997
5701
5420
5152
4898
4656
4427
4208
4001
3803
3616
3437
LDGT
LDGT
0-6000
19496
18384
17308
16267
15260
14289
13352
12451
11584
10752
9955
9194
8467
7775
7118
6496
5909
5356
4839
4357
3909
3497
3120
2777
2470
2197
1959
1756
1589
1456
LDGT
6001-8500
21331
19865
18500
17228
16044
14942
13915
12959
12068
11239
10466
9747
9077
8453
7872
7331
6827
6358
5921
5514
5135
4782
4454
4148
3863
3597
3350
3120
2905
2706
LDDT
LDDT
0-6000
27059
24384
21973
19801
17843
16079
14490
13057
11766
10603
9555
8610
7759
6992
6301
5678
5116
4610
4155
3744
3374
3040
2740
2469
2225
2005
1807
1628
1467
1322
LDDT
6001-8500
26040
24018
22154
20434
18848
17385
16036
14791
13643
12584
11607
10706
9875
9109
8402
7749
7148
6593
6081
5609
5174
4772
4402
4060
3745
3454
3186
2939
2711
2500
HDGV
2B-3
8501-14000
19977
18779
17654
16596
15601
14666
13787
12961
12184
11454
10768
10122
9516
8946
8409
7905
7432
6986
6568
6174
5804
5456
5129
4822
4533
4261
4006
3766
3540
3328
4-8
>14000
21394
19692
18125
16683
15356
14134
13010
11975
11022
10145
9338
8595
7911
7282
6703
6169
5679
5227
4811
4428
4076
3752
3453
3178
2926
2693
2479
2281
2100
1933
HDGB
S.BUS
ANY
WGT.
(a)
T.BUS
ANY
WGT.
35123
31914
28999
26350
23942
21755
19768
17962
16321
14830
13475
12244
11126
10109
9186
8347
7584
6891
6262
5690
5170
4698
4268
3879
3524
3202
2910
2644
2402
2183
LDV Light duty vehicle
LDGV Light duty gasoline vehicle
LDDV Light duty diesel vehicle
LDGT Light duty gasoline truck
LDDT Light duty diesel truck
HDGV Heavy duty gasoline vehicle
HDGB Heavy duty gasoline bus
(a)
Average school bus mileage for all ages = 9,939
-16-
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Table 6. Annual Mileage Accumulation (Curve Fit Data)
(12 months estimate)
(continued)
U.S. Levels
Vehicle
Age
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
HDDV
2B
8501-10000
27137
24831
22721
20791
19024
17407
15928
14575
13336
12203
11166
10217
9349
8555
7828
7163
6554
5997
5488
5021
4595
4204
3847
3520
3221
2947
2697
2468
2258
2066
3
10001-14000
32751
28984
25650
22699
20088
17778
15733
13923
12321
10904
9650
8540
7557
6688
5919
5238
4635
4102
3630
3213
2843
2516
2227
1971
1744
1543
1366
1209
1070
947
4-5
14001-19500
30563
28622
26805
25103
23509
22016
20618
19309
18083
16935
15860
14853
13910
13026
12199
11425
10699
10020
9384
8788
8230
7707
7218
6760
6331
5929
5552
5200
4869
4560
6-7
19501-33000
40681
36872
33420
30291
27455
24885
22555
20443
18529
16795
15222
13797
12505
11335
10273
9312
8440
7650
6933
6284
5696
5163
4679
4241
3844
3484
3158
2862
2594
2352
8A
33001-60000
87821
78257
69735
62141
55374
49343
43970
39181
34915
31112
27724
24705
22015
19617
17481
15577
13881
12369
11022
9822
8752
7799
6950
6193
5518
4918
4382
3905
3480
3101
8B
>60000
124208
112590
102060
92514
83861
76017
68907
62462
56620
51324
46523
42172
38228
34652
31411
28473
25810
23396
21208
19224
17426
15796
14319
12979
11765
10665
9667
8763
7944
7201
HDDB
S.BUS
ANYWGT.
(a)
T.BUS
ANY WGT.
45171
43731
42337
40987
39681
38416
37191
36005
34857
33746
32670
31629
30620
29644
28699
27784
26898
26041
25211
24407
23629
22875
22146
21440
20757
20095
19454
18834
18234
17652
HDDVHeavy duty diesel vehicle
HDDB Heavy duty diesel bus
(a) Average school bus mileage for all ages = 9,939
-17-
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4.0 Vehicle Counts for VMT Weighting Calculations
In addition to providing emission factors, MOBILE6 also provides the user with a
distribution of the vehicle miles traveled (VMT) by each vehicle type for a given calendar year.
This is known as the VMT mix. To calculate the VMT mix, the model requires an estimate of
the total vehicle population, or "vehicle count," by vehicle class for each calendar year.
MOBILES contained vehicle counts for calendar years 1982 through 2020; 1982 vehicle counts
were used for all pre-1982 vehicle counts. MOBILE6 will use the 1982 through 1990 vehicle
counts from MOBILES because!990 is the last year for which actual in-use vehicle data was
collected for MOBILES. However, MOBILE6 requires additional vehicle count estimates for
1991 and later calendar years. The methodology for obtaining these vehicle counts is explained
below.
The following general formula describes how total vehicle count for a future calendar
year would ideally be determined for each vehicle category:
VC x = (VC x_! + Sales x) - ( Scrappage x)
where: VC = total vehicle count for that vehicle category
Sales = number of new vehicles sold
Scrappage = number of vehicles removed from fleet
x = the calendar year in question
In the above scenario, the vehicle count for a future year would be calculated by adding
an estimated number of new vehicle sales to the previous year's total fleet and subtracting an
estimated number of vehicles that were likely to be removed from the fleet during that year; this
is known as scrappage.
Estimating vehicle populations for future calender years requires some engineering
judgements regarding changes in the number of new vehicles being sold and driven each year, as
well as the number of vehicles being removed from the road due to scrappage. Making such
judgements requires an analysis of the most current sources of data characterizing in-use vehicle
population size, sales growth estimates, and scrappage rates for light-and heavy-duty vehicles.
Sections 4.1 describes the methodologies EPA used to determine future vehicle counts for
calendar years 1996 through 2050, Section 4.2 presents fuel splits by vehicle class, and Section
4.3 describes the method EPA used to interpolate between the MOBILES data and the new data
for the missing years (1991 through 1995).
4.1 Methodology for Estimating Vehicle Counts for Calendar Years 1996 through 2050
As noted in Section 1.0, EPA contracted with Arcadis, Geraghty & Miller in 1998 to
assess the actual in-use vehicle fleet for eighteen vehicle categories (see Table 1) as of July 1,
1996. These data serve as the baseline for all future vehicle count calculations presented in the
current report.
-18-
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The Arcadis report provides total in-use vehicles by eighteen vehicle class categories.
Ideally, separate vehicle class-specific sales growth and scrappage rates would have been applied
to each of the vehicle categories to provide a relative sense of the effects of vehicle-type-specific
trends. For example, there is some evidence that suggests that sales of several heavy-duty truck
categories have slowed considerably in recent years, and will continue to decline in the future; it
may be speculated that these vehicles are being replaced by smaller or larger heavy-duty trucks.2
Unfortunately, at the time of this analysis, adequate sales growth and scrappage rates for
individual vehicle categories were not available. Therefore, EPA has evaluated general sales
growth and vehicle scrappage trends for the total light-duty vehicle in-use fleet and the total
heavy-duty vehicle in-use fleet, and has attempted, where possible, to reflect some of the
differences between vehicle categories.
The following two sections detail the methods used to characterize light-duty future
vehicle counts and heavy-duty future vehicle counts, respectively.
4.1.1 Light-duty Vehicle Counts for 1996 through 2050
To calculate future light-duty vehicles counts, EPA began this analysis with the total
number of light-duty vehicles for July 1, 1996, which is the sum of all of the light-duty categories
specified in the Arcadis Report (176,375,176 light-duty vehicles,).
Estimates of total light-duty vehicle sales were needed for calendar years 1997 through
2050. Baseline sales data were derived from the EPA's Certification and Fuel Economy
Information System (CFEIS) database3. Due to reporting problems, complete sales data for 1997
was not available; therefore, for this analysis, the most up-to-data sales data was ^projected 1998
sales estimate (14,633,231). To determine annual sales of light-duty vehicles beyond 1998 (and
to estimate the missing 1997 sales total), EPA consulted the 1999 Department of Energy Annual
Energy Outlook (AEO99)4. AEO99 reports a light-duty vehicle sales growth rate of 0.5%
annually for 1997 through 2020. By applying this growth rate to the light-duty unit sales reported
for 1998 in the CFEIS database, EPA determined unit sales estimates for calendar years 1997
through 2020.
To determine the effects of annual vehicle scrappage on the light-duty fleet, EPA
employed scrappage rates reported in the 1996 World Vehicle Forecasts and Strategies5 report.
This document defines scrappage as "the number of vehicles scrapped or otherwise removed
from circulation in any given year;" this value is reported as a percentage of the "pare," or
number of vehicles in use in any given year. The 1996 World Vehicle Forecasts and Strategies
document does not provide vehicle class-specific scrappage rates, instead reporting scrappage
rates for "passenger cars" and "commercial vehicles." EPA has assumed the scrappage rates
presented for "passenger cars" to be representative of the light-duty vehicle fleet for this analysis;
these rates are listed in Table 7.
-19-
-------
Table 7. "Passenger Car" Scrappage Rates used for Light-duty Vehicle Scrappage.
Calendar Year*
1995-1999
2000-2004
2005-2009
2010-2014
2015-2020
Annual Rate of
Scrappage
(as % of "Pare")
5.77
5.70
6.09
6.34
6.56
* =The 1996 World Vehicle Forecasts and Strategies document reports "scrappage rates as % of pare" for
calendar years 1995,2000,2005,2010, and 2015. EPA has assumed that the annual scrappage rate remains the
same for years not explicitly stated (i.e., 1996 through 1999 have the same scrappage rate as 1995, etc).
It is important to note that these scrappage rates represent the percentage of the total in-
use fleet that is removed from circulation; therefore, scrappage becomes a function of the
previous years fleet total plus the current year's calculated sales. The general vehicle count
formula therefore becomes:
VCX = (VCX., + Sales x)x(l_SRx)
where: VC = vehicle count
Sales = number of vehicle sold
SR = % of in-use fleet that is scrapped
x = the current calendar year
To illustrate the calculation, starting with the 1996 total light-duty vehicle count:
VC1997 (VC1996
= (VC1996 + Sales
CqlpC \ X
kJCllt'i3J997 J
1997 ) " (( * ^1996
(1 - SR1997)
Sales1997) x SR1997)
VC1997 = (176, 385, 176 + 14,560,429) - ((176, 385, 176 +14,560,429) x 5.77%)
VC19977 =190,945,605-(190,945,605 - 11,017,561)
VC1997= 179,928,044
This calculation was performed for all calendar years 1997 through 2020. Since none of
the data sources used here projected beyond the year 2020, MOBILE6 will use the 2020 vehicle
count for calendar years 2021 through 2050. Table 8 lists the calculated unit sales, the scrappage
rates, and total light-duty vehicle count projections for 1997 through 2050.
-20-
-------
Table 8. Calculated Sales, Scrappage Rates, and Vehicle Counts for Light-duty Vehicles by
Calendar Year
Calendar
Year
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020-2050
Calculated
Sales
N/A
14,560,429
14,633,231
14,706,397
14,779,929
14,853,829
14,928,098
15,002,738
15,077,752
15,153,141
15,228,907
15,305,051
15,381,576
15,458,484
15,535,777
15,613,456
15,691,523
15,769,980
15,848,830
15,928,074
16,007,715
16,087,753
16,168,192
16,249,033
16,330,278
Scrappage
(% of in-use
fleet)
N/A
5.77
5.77
5.77
5.70
5.70
5.70
5.70
5.70
6.09
6.09
6.09
6.09
6.09
6.34
6.34
6.34
6.34
6.34
6.56
6.56
6.56
6.56
6.56
6.56
Total LD
Vehicles
176,385,176
179,928,044
183,335,089
186,614,492
189,914,940
193,096,949
196,167,619
199,133,647
202,001,349
203,929,782
205,811,924
207,650,951
209,449,847
211,211,414
212,371,419
213,530,633
214,689,471
215,848,322
217,007,553
217,655,051
218,334,488
219,044,142
219,782,406
220,547,776
221,338,854
Note: 1998 Sales are "projected sales" and represent the base sales for calculating sales in all other years. Sales are
grown at a rate of 0.5% annually. 1997 sales are estimated from the 1998 base sales using the following formula:
1998 Sales/1.005.
-21-
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Total light-duty vehicle counts by calendar year were then split into cars and trucks
(hereafter referred to as "light-duty vehicles" and "light-duty trucks," respectively). To do this,
EPA used a methodology for predicting car/truck proportions outlined in an EPA report entitled
"VMT and Emission Implications of Growth in Light Truck Sales."6 This method assumes that
sales of light-duty trucks will increase and ultimately surpass sales of light-duty cars in the near
future. In keeping with other agency analyses, EPA assumed that the car to truck sales ratio will
ultimately stabilize at 40:60 for calendar years 2008 on.7 These sales rates were then used to
calculate light-duty vehicle to light-duty truck "stock" splits, or the relative relationship of car to
truck registrations in the total fleet. Due to assumptions inherent in this methodology, the
predicted 1996 stock split did not exactly match the split determined by Arcadis for July 1, 1996.
To account for this difference, EPA fit a line through the Arcadis 1996 splits and the predicted
2000 split to join the two sources of data. As a result, EPA calculated the following car to truck
stock (in-use fleet) relationships:
Table 9. Light-duty Vehicle / Light-duty Truck Fleet Distribution Split
Calendar Year
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020-2050
Percentage of Total
Light-duty Class
Light-duty
Vehicles
68.2%
66.0%
63.9%
61.7%
59.6%
58.0%
56.6%
55.0%
53.4%
52.0%
50.3%
48.7%
47.0%
45.5%
44.1%
42.8%
41.6%
40.5%
39.6%
38.8%
38.0%
37.3%
36.8%
36.3%
35.9%
Light-duty
Trucks
31.8%
34.0%
36.1%
38.3%
40.4%
42.0%
43.4%
45.0%
46.6%
48.0%
49.7%
51.3%
53.0%
54.5%
55.9%
57.2%
58.4%
59.5%
60.4%
61.2%
62.0%
62.7%
63.2%
63.7%
64.1%
-22-
-------
Light-duty trucks are further disaggregated into two categories: light-duty trucks less than
6,000 Ibs GVWR and light-duty trucks greater than 6,000 Ibs GVWR. These two categories
correspond with the federal regulatory weight classes that were in place at the time that
MOBILES and older versions of the model were released. This split is made by again referring
the 1996 Arcadis report. The Arcadis report indicated that, as of July 1, 1996, 73.72% of all
light-duty trucks were rated as less than 6,000 Ibs GVWR, and 26.28% were rated as greater than
6,000 Ibs GVWR. Due to a lack of data characterizing this split in future years, EPA has
assumed this ratio for all future years as well as 1996.
Federal regulations implemented in!994 redefined the light-duty truck classes. As a result
of these new definitions, the MOBILE model requires further disaggregation of the two light-
duty truck groupings into four regulatory classes: light-duty trucks class 1 (LDT1), light-duty
trucks class 2 (LDT2), light-duty trucks class 3 (LDT3) and light-duty trucks class 4 (LDT4) for
calendar years 1994 through 2050. Table 10 briefly describes the new light-duty truck classes; a
detailed explanation of the new definitions is provided in Appendix C.
Table 10. Description of New EPA Light-duty Truck Classifications
MOBILES
Category
Light-duty truck 1
Light-duty truck 1
Light-duty truck 2
Light-duty truck 2
MOBILE6
Category
Light-duty truck 1
Light-duty truck 2
Light duty truck 3
Light duty truck 4
Gross Vehicle
Weight Rating
<6000 Ibs
<6000 Ibs
>6000 Ibs
>6000 Ibs
Loaded Vehicle
Weight Rating
< 3750 Ibs
>3750 Ibs
< 3750 Ibs
(Average Loaded
Vehicle Weight)*
>5750 Ibs
(Average Loaded
Vehicle Weight)*
Description
Most small SUVs, most small pickups
All minivans, "Compact" SUVs (e.g.,
Explorer), most Dakota and T100
pickups
Most 1/2 -ton pickups, Base full-size
vans, and intermediate SUVs (e.g., Land
Cruiser)
Some 1/2 and 3/4 ton pickups, some full-
size vans, and larger SUVs (e.g.,
Expedition)
* Average Loaded Vehicle Weight is the average of the gross vehicle weight and the curb weight
As these truck class definitions are relatively new, little data exists to allow for splitting
trucks into these categories. To get a sense of how the older light-duty truck category should be
distributed into the four federal categories, EPA again used the 1998 Certification and Fuel
Economy Information System (CFEIS) database8. Using 1998 sales data, EPA was able to
determine that in 1998, 23.1% of all light-duty trucks less than 6,000 Ibs GVWR would be
classified as LDT1 and 76.9% of all light-duty trucks less than 6,000 Ibs GVWR would be
classified as LDT2. Further, 68.5% of all light-duty trucks greater than 6,000 Ibs GVWR would
be classified as LDT3 and 31.5% of all light-duty trucks greater than 6,000 Ibs GVWR would be
classified as LDT4.
-23-
-------
Table 11. Distribution of Light-duty Trucks <6,000 Ibs GVWR into Federally-defined
Light-duty Truck Classes LDT1 and LDT2
Federally Defined
Light-duty Truck
Category
LDT1
LDT2
Percentage of
Total
LDT<6000 Ibs
23.1
76.9
Table 12 Distribution of Light-duty Trucks >6,000 Ibs GVWR into Federally-defined
Light-duty Truck Classes LDT3 and LDT4
Federally Defined
Light-duty Truck
Category
LDT3
LDT4
Percentage of
Total
LDT>6000 Ibs
68.5
31.5
In lieu of other sources of data, these sales relationships were assumed to represent the
general vehicle class splits in the total vehicle fleet. Therefore, the above ratios were applied to
light-duty trucks in calendar years 1996 through 2050. The final class-specific vehicle counts for
all light duty classes in calendar years 1996 though 2050 are presented in Table 13.
-24-
-------
Table 13. Vehicle Counts by Calendar Year for Light-duty Vehicles
Calendar
Year
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020 - 2050
Light-duty Vehicle Class
Light-duty
Vehicles
120,213,037
118,773,800
117,096,045
115,193,551
113,163,114
112,067,320
110,950,294
109,439,432
107,898,603
105,955,155
103,575,222
101,040,538
98,431,413
96,043,330
93,587,131
91,290,697
89,345,016
87,503,888
85,917,827
84,384,402
82,971,891
81,805,681
80,793,310
79,950,083
79,436,359
Light-duty
Truck Class 1
9,566,078
10,414,527
11,280,465
12,162,938
13,070,784
13,799,291
14,512,453
15,274,865
16,025,634
16,685,013
17,410,842
18,155,682
18,906,365
19,613,047
20,228,884
20,817,379
21,346,077
21,856,971
22,324,492
22,695,902
23,052,159
23,371,618
23,669,750
23,943,693
24,165,899
Light-duty
Truck Class 2
31,845,513
34,670,004
37,552,716
40,490,475
43,512,698
45,937,900
48,312,019
50,850,090
53,349,406
55,544,480
57,960,767
60,440,343
62,939,370
65,291,919
67,342,044
69,301,145
71,061,181
72,761,950
74,318,331
75,554,755
76,740,738
77,804,216
78,796,699
79,708,656
80,448,384
Light-duty
Truck Class 3
10,110,975
11,007,753
11,923,017
12,855,757
13,815,316
14,585,319
15,339,104
16,144,943
16,938,478
17,635,416
18,402,589
19,189,856
19,983,299
20,730,235
21,381,152
22,003,168
22,561,981
23,101,976
23,596,128
23,988,694
24,365,244
24,702,900
25,018,014
25,307,561
25,542,425
Light-duty
Truck Class 4
4,649,573
5,061,960
5,482,847
5,911,772
6,353,028
6,707,118
7,053,749
7,424,317
7,789,227
8,109,717
8,462,504
8,824,532
9,189,400
9,532,882
9,832,208
10,118,245
10,375,217
10,623,537
10,850,774
11,031,297
11,204,455
11,359,728
11,504,634
11,637,783
11,745,787
Total Light-duty
Vehicles and
Trucks
176,385,176
179,928,044
183,335,089
186,614,492
189,914,940
193,096,949
196,167,619
199,133,647
202,001,349
203,929,782
205,811,924
207,650,951
209,449,847
211,211,414
212,371,419
213,530,633
214,689,471
215,848,322
217,007,553
217,655,051
218,334,488
219,044,142
219,782,406
220,547,776
221,338,854
For motorcycles, MOBILE6 will use the same vehicle count assumptions that were
developed for MOBILES, as noted in Appendix A.
-25-
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4.1.2 Heavy-duty Vehicle Counts for 1996 through 2050
To estimate future vehicle counts for heavy-duty vehicles, EPA again used the data
provided in the Arcadis report for July 1, 1996 to obtain a heavy-duty vehicle total (11,897,859
heavy-duty vehicles). Confidential sales data supplied by heavy-duty truck manufacturers were
used to determine heavy-duty gasoline vehicle sales for 1996. Unfortunately, at the time of this
analysis, heavy-duty diesel sales data were only available from the confidential sales data for 1995.
To calculate total heavy-duty diesel sales for 1996, a 2% sales growth rate was assumed between
1995 and 1996, and this growth rate was applied to the 1995 heavy-duty diesel sales total. This
figure was then added to the 1996 heavy-duty gasoline sales, resulting in a total heavy-duty
vehicle sales figure for 1996 of 1,071,131 vehicles.
The 1997 Regulatory Impact Analysis for heavy-duty engines predicts a linear growth rate
of 2.0% for heavy-duty vehicles annually through the year 2020 (see reference 2 in bibliography).
This rate was used to calculate total heavy-duty sales for calendar years 1997 through 2020. As
with light-duty vehicles, EPA relied on the 1996 World Vehicle Forecasts and Strategies report for
heavy-duty scrappage rates. Again, note that this document defines scrappage as "the number of
vehicles scrapped or otherwise removed from circulation in any given year;" this value is reported
as a percentage of the "pare," or number of vehicles in use in any given year. The report contains
"commercial vehicle" scrappage rates; for this analysis, EPA assumed commercial vehicles were
equivalent to all heavy-duty vehicle categories. These scrappage rates are listed in Table 14.
Table 14. "Commercial Vehicle" Scrappage Rates used for Heavy-duty Vehicle Scrappage
Calendar Year*
1995-1999
2000-2004
2005-2009
2010-2014
2015-2020
Annual Rate of
Scrappage
(as % of "Pare")
4.39
5.55
6.45
7.12
7.57
-26-
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As described in Section 4.1.1., the following formula is used to calculate vehicle counts for future
calendar years:
VCX = VCX = (VC x_! + Sales x) x (1- SR x)
where: VC = vehicle count
Sales = number of vehicle sold
SR = % of in-use fleet that is scrapped
x = the calendar year in question
This calculation was performed for calendar years 1997 through 2020 to obtain total heavy-duty
vehicle counts. The calculated sales, scrappage rates, and total heavy-duty vehicle counts are listed
in Table 15.
-27-
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Table 15. Calculated Sales, Scrappage Rates, and Vehicle Counts for Heavy-duty Vehicles
by Calendar Year
Calendar
Year
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020 - 2050
Calculated
Sales
N/A
1,092,554
1,113,976
1,135,399
1,156,821
1,178,244
1,199,667
1,221,089
1,242,512
1,263,935
1,285,357
1,306,780
1,328,202
1,349,625
1,371,048
1,392,470
1,413,893
1,435,316
1,456,738
1,478,161
1,499,583
1,521,006
1,542,429
1,563,851
1,585,274
Scrappage
(% of in-use
fleet)
N/A
4.39%
4.39%
4.39%
5.55%
5.55%
5.55%
5.55%
5.55%
6.45%
6.45%
6.45%
6.45%
6.45%
7.12%
7.12%
7.12%
7.12%
7.12%
7.57%
7.57%
7.57%
7.57%
7.57%
7.57%
Total
Heavy-duty
Vehicles
11,897,859
12,420,134
12,939,962
13,457,453
13,803,182
14,149,957
14,497,720
14,846,415
15,195,992
15,398,261
15,607,525
15,823,332
16,045,260
16,272,915
16,387,713
16,514,234
16,651,644
16,799,168
16,956,086
17,038,774
17,135,004
17,243,750
17,364,065
17,495,073
17,635,965
To provide vehicle counts for the ten heavy-duty vehicle categories (class 2B, class 3, class
4, class 5, class 6, class 7, class 8A, class 8B, school buses and transit buses), the 1996 Arcadis
report was used. Ratios of vehicle population in each of the heavy-duty vehicle categories to the
total heavy-duty vehicle population were calculated for the heavy-duty vehicle categories reported
in the Arcadis report for the total in-use vehicle populations as of July 1, 1996. However, several
-28-
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of the Arcadis report categories represented aggregate classes, specifically heavy-duty gasoline
vehicles classes 2B-3, heavy-duty gasoline vehicles classes 4-8, heavy-duty diesel vehicles classes
4-5, and heavy-duty diesel vehicles classes 6-7. To provide vehicle counts for the ten non-fuel
specific heavy-duty vehicle classes represented in MOBILE6, these aggregate classes were split
using ratios of projected 1996 sales in each of the ten categories to the total projected 1996 sales
from a 1992 Navistar study.9 These percentages are listed in Table 16. The final splits were
computed by summing the individual fuel-specific categories to determine the total for each of the
ten categories.
Table 16. Percentage of Total Heavy-duty Vehicles by Vehicle Class
Heavy-Duty
Class
2B
3
4
5
6
7
8A
8B
School Bus
Transit Bus
% of Total Heavy-duty
Vehicle by Class
50.20%
4.44%
3.29%
2.93%
9.15%
9.65%
4.96%
11.43%
3.48%
0.47%
As with light-duty vehicles, due to a lack of other predictors, the above ratios were applied
to heavy-duty trucks in calendar years 1996 through 2050. The final class-specific vehicle counts
for all light duty classes in calendar years 1996 though 2050 are presented in Table 17.
-29-
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Table 17. Vehicle Counts by Calendar Year for Heavy-duty Vehicles
Calendar
Year
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020 -2050
Heavy-duty Vehicle Class
Class 2B
5,972,563
6,234,738
6,495,685
6,755,458
6,929,009
7,103,086
7,277,658
7,452,698
7,628,181
7,729,717
7,834,765
7,943,097
8,054,502
8,168,782
8,226,408
8,289,920
8,358,898
8,432,953
8,511,724
8,553,232
8,601,538
8,656,127
8,716,524
8,782,288
8,853,014
Class 3
528,582
551,785
574,879
597,870
613,229
628,635
644,085
659,576
675,107
684,093
693,390
702,978
712,837
722,951
728,051
733,672
739,777
746,331
753,302
756,976
761,251
766,082
771,427
777,247
783,507
Class 4
391,443
408,626
425,728
442,754
454,129
465,538
476,979
488,451
499,952
506,607
513,492
520,592
527,894
535,383
539,160
543,323
547,844
552,697
557,860
560,580
563,746
567,324
571,283
575,593
580,228
Class 5
348,582
363,883
379,113
394,274
404,404
414,563
424,752
434,968
445,210
451,136
457,267
463,590
470,092
476,761
480,125
483,832
487,857
492,180
496,777
499,199
502,019
505,205
508,730
512,568
516,696
Class 6
1,089,074
1,136,881
1,184,464
1,231,832
1,263,479
1,295,221
1,327,053
1,358,971
1,390,970
1,409,485
1,428,640
1,448,394
1,468,708
1,489,547
1,500,055
1,511,636
1,524,214
1,537,717
1,552,081
1,559,650
1,568,458
1,578,412
1,589,425
1,601,417
1,614,314
Class 7
1,147,715
1,198,095
1,248,240
1,298,159
1,331,510
1,364,961
1,398,507
1,432,144
1,465,865
1,485,377
1,505,564
1,526,381
1,547,789
1,569,750
1,580,824
1,593,028
1,606,283
1,620,514
1,635,651
1,643,628
1,652,910
1,663,400
1,675,006
1,687,644
1,701,235
Class 8A
589,867
615,760
641,531
667,187
684,328
701,520
718,761
736,049
753,380
763,408
773,783
784,482
795,484
806,771
812,462
818,735
825,547
832,861
840,641
844,740
849,511
854,903
860,868
867,363
874,348
Class 8B
1,360,346
1,420,060
1,479,495
1,538,663
1,578,192
1,617,840
1,657,602
1,697,470
1,737,439
1,760,566
1,784,492
1,809,166
1,834,541
1,860,570
1,873,695
1,888,161
1,903,872
1,920,739
1,938,680
1,948,134
1,959,137
1,971,570
1,985,327
2,000,305
2,016,414
School
Buses
413,819
431,984
450,064
468,063
480,088
492,149
504,245
516,373
528,531
535,566
542,845
550,351
558,070
565,988
569,980
574,381
579,160
584,291
589,749
592,625
595,972
599,754
603,939
608,495
613,396
Transit
Buses
55,869
58,321
60,762
63,192
64,816
66,444
68,077
69,715
71,356
72,306
73,289
74,302
75,344
76,413
76,952
77,546
78,191
78,884
79,621
80,009
80,461
80,972
81,537
82,152
82,814
Total
11,897,859
12,420,134
12,939,962
13,457,453
13,803,182
14,149,957
14,497,720
14,846,415
15,195,992
15,398,261
15,607,525
15,823,332
16,045,260
16,272,915
16,387,713
16,514,234
16,651,644
16,799,168
16,956,086
17,038,774
17,135,004
17,243,750
17,364,065
17,495,073
17,635,965
-30-
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4.2. Gasoline/Diesel Fuel Ratios
The MOBILE model provides the user with fuel-specific data for vehicle counts.
Therefore, it is necessary to provide class specific gasoline to diesel vehicle ratios for each of the
five light-duty vehicle types and the eight heavy-duty vehicle types represented in MOBILE6.
Again, data from the Arcadis report was used. The Arcadis report contains fuel-specific vehicle
counts as of July 1, 1996 by model year. Using this data, ratios of gasoline vehicles to diesel
vehicles for each vehicle category and model years 1972 through 1996 were obtained. For
modeling purposes, vehicles produced in model years later than 1996 are assumed to have the same
gasoline to diesel ratio as the 1996 vehicles. This assumption was necessary as there were no
known sources of data predicting future trends in sales of trucks by fuel type. The gasoline/diesel
ratios for all vehicle classes are presented in Table 18.
-31-
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Table 18. Gasoline/ Diesel Fractions for All Vehicle Classes
MODEL YEAR
1996 and later
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
1985
1984
1983
1982
1981
1980
1979
1978
1977
1976
1975
1974
1973
1972 and earlier
LIGHT-DUTY VEHICLE CLASSES
Gasoline
Vehicles
99.91%
99.94%
99.99%
99.97%
99.94%
99.87%
99.96%
99.96%
99.99%
99.73%
99.68%
99.03%
98.38%
97.59%
94.90%
92.94%
96.10%
97.31%
98.86%
99.07%
98.63%
98.45%
99.33%
99.33%
99.33%
Diesel
Vehicles
0.09%
0.06%
0.01%
0.03%
0.06%
0.13%
0.04%
0.04%
0.01%
0.27%
0.32%
0.97%
1.62%
2.41%
5.10%
7.06%
3.90%
2.69%
1.14%
0.93%
1.37%
1.55%
0.67%
0.67%
0.67%
Gasoline
Trucks 1 and 2
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
99.93%
99.67%
99.52%
98.80%
97.77%
93.44%
93.84%
95.61%
96.84%
97.41%
100.00%
98.13%
89.62%
88.30%
88.30%
88.30%
Diesel
Trucks 1 and 2
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.07%
0.33%
0.48%
1.20%
2.23%
6.56%
6.16%
4.39%
3.16%
2.59%
0.00%
1.87%
10.38%
11.70%
11.70%
11.70%
Gasoline
Trucks 3 and 4
98.74%
98.85%
98.89%
98.55%
98.85%
98.71%
99.04%
99.17%
99.28%
99.18%
98.76%
98.65%
98.31%
97.91%
97.44%
99.87%
99.94%
99.89%
99.99%
100.00%
100.00%
100.00%
99.99%
99.99%
99.99%
Diesel
Trucks 3 and 4
1.26%
1.15%
1.11%
1.45%
1.15%
1.29%
0.96%
0.83%
0.72%
0.82%
1.24%
1.35%
1.69%
2.09%
2.56%
0.13%
0.06%
0.11%
0.01%
0.00%
0.00%
0.00%
0.01%
0.01%
0.01%
-32-
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Table 18. Gasoline/ Diesel Fractions for All Vehicle Classes (continued)
MODEL YEAR
1996 and later
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
1985
1984
1983
1982
1981
1980
1979
1978
1977
1976
1975
1974
1973
1972 and earlier
HEAVY-DUTY VEHICLE CATEGORIES
Gasoline
2B
80.02%
74.22%
74.85%
67.37%
72.16%
70.37%
76.16%
79.42%
82.44%
80.42%
72.74%
72.57%
69.96%
70.82%
71.41%
98.62%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
Diesel
2B
19.98%
25.78%
25.15%
32.63%
27.84%
29.63%
23.84%
20.58%
17.56%
19.58%
27.26%
27.43%
30.04%
29.18%
28.59%
1.38%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
Gasoline
3
32.26%
22.85%
20.90%
18.95%
19.32%
17.20%
15.23%
20.60%
25.12%
22.11%
21.58%
38.55%
48.61%
49.68%
57.23%
99.21%
100.00%
100.00%
99.99%
99.97%
99.90%
99.72%
97.52%
0.00%
0.00%
Diesel
3
67.74%
77.15%
79.10%
81.05%
80.68%
82.80%
84.77%
79.40%
74.88%
77.89%
78.42%
61.45%
51.39%
50.32%
42.77%
0.79%
0.00%
0.00%
0.01%
0.03%
0.10%
0.28%
2.48%
100.00%
100.00%
Gasoline
4
13.94%
15.27%
19.52%
16.69%
20.99%
26.84%
27.25%
28.42%
43.53%
68.22%
77.93%
80.32%
84.30%
92.62%
96.59%
95.86%
99.97%
100.00%
100.00%
100.00%
97.41%
99.22%
99.96%
99.10%
98.88%
Diesel
4
86.06%
84.73%
80.48%
83.31%
79.01%
73.16%
72.75%
71.58%
56.47%
31.78%
22.07%
19.68%
15.70%
7.38%
3.41%
4.14%
0.03%
0.00%
0.00%
0.00%
2.59%
0.78%
0.04%
0.90%
1.12%
Gasoline
5
53.53%
56.16%
63.30%
58.75%
65.38%
72.29%
72.70%
73.84%
84.57%
93.85%
96.17%
96.67%
97.45%
98.89%
99.51%
99.40%
100.00%
100.00%
100.00%
100.00%
99.63%
99.89%
99.99%
99.87%
99.84%
Diesel
5
46.47%
43.84%
36.70%
41.25%
34.62%
27.71%
27.30%
26.16%
15.43%
6.15%
3.83%
3.33%
2.55%
1.11%
0.49%
0.60%
0.00%
0.00%
0.00%
0.00%
0.37%
0.11%
0.01%
0.13%
0.16%
Gasoline
6
37.00%
39.22%
47.54%
42.33%
47.11%
42.12%
43.83%
54.63%
57.84%
52.66%
52.95%
54.75%
56.90%
64.31%
63.10%
55.87%
69.06%
83.21%
86.10%
91.92%
95.24%
96.35%
97.12%
97.26%
97.03%
Diesel
6
63.00%
60.78%
52.46%
57.67%
52.89%
57.88%
56.17%
45.37%
42.16%
47.34%
47.05%
45.25%
43.10%
35.69%
36.90%
44.13%
30.94%
16.79%
13.90%
8.08%
4.76%
3.65%
2.88%
2.74%
2.97%
Gasoline
7
14.37%
15.57%
20.57%
17.34%
20.28%
17.21%
18.23%
25.60%
28.16%
24.12%
24.33%
25.69%
27.39%
33.98%
32.83%
26.56%
38.93%
58.60%
63.90%
76.47%
85.11%
88.30%
90.60%
91.03%
90.34%
Diesel
7
85.63%
84.43%
79.43%
82.66%
79.72%
82.79%
81.77%
74.40%
71.84%
75.88%
75.67%
74.31%
72.61%
66.02%
67.17%
73.44%
61.07%
41.40%
36.10%
23.53%
14.89%
11.70%
9.40%
8.97%
9.66%
-33-
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Table 18. Gasoline/ Diesel Fractions for All Vehicle Classes (continued)
MODEL YEAR
1996 and later
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
1985
1984
1983
1982
1981
1980
1979
1978
1977
1976
1975
1974
1973
1972 and earlier
HEAVY-DUTY VEHICLE CATEGORIES
Gasoline
8A
0.08%
0.11%
0.13%
0.11%
0.23%
0.16%
0.18%
0.21%
0.31%
0.22%
0.20%
0.21%
0.24%
0.31%
0.22%
0.18%
0.26%
0.35%
0.36%
0.51%
0.80%
0.64%
1.81%
1.88%
2.80%
Diesel
8A
99.92%
99.89%
99.87%
99.89%
99.77%
99.84%
99.82%
99.79%
99.69%
99.78%
99.80%
99.79%
99.76%
99.69%
99.78%
99.82%
99.74%
99.65%
99.64%
99.49%
99.20%
99.36%
98.19%
98.12%
97.20%
Gasoline
8A
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
Diesel
8B*
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
100.00%
-34-
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4.3 Interpolating Between MOBILES and MOBILE6 Vehicle Counts
MOBILES contains vehicle counts for calendar years 1982 through 2050 for three different
light-duty vehicle classes (light-duty vehicles, light-duty trucks <6,000 Ibs, and light-duty gasoline
trucks >6,000 Ibs, ) and two heavy-duty truck categories (heavy-duty gasoline trucks and heavy-
duty diesel trucks). MOBILES uses a special algorithm to split the light-duty classes into gasoline
and diesel fuel categories. The MOBILES vehicle counts were based on actual data through
calendar year 1990, and projections were made for 1990 and later calendar years.
MOBILE6 will include vehicle counts for five light-duty vehicle classes, eight heavy-duty
truck classes, and two heavy-duty bus classes. These classes are not fuel specific; an algorithm
similar to that used in MOBILES for light-duty vehicles will be used in MOBILE6 to split the
fifteen classes into gasoline and diesel fuel categories using the gasoline/ diesel splits calculated in
Section 4.2. These vehicle counts are based on actual data from 1996 Arcadis report and vehicle
counts for 1996 and later calendar years are projected.
Since the MOBILE model is designed to allow the user to make VMT split calculations for
calendar years 1982 through 2050, data from MOBILES will also be included in MOBILE6 to
cover earlier model years. This poses two challenges: 1) expanding the MOBILES vehicle classes
to match those in MOBILE6; and 2) addressing the 1991 through 1995 data gap which exists
between the MOBILES vehicle counts for 1990 and earlier (which are based on actual data) and the
1996 and later projections presented in this report (which are also based on actual data).
To expand the 1982 through 1990 calendar years vehicle count data for the three MOBILES
light-duty vehicle classes to the five MOBILE6 categories, EPA has maintained the relative
relationship between light-duty trucks less than 6,000 Ibs and light-duty trucks greater than 6,000
Ibs for the MOBILES data, but has used the CFEIS data described in Section 4.1.1 to separate this
data into the new regulatory categories for 1994 and 1995 calendar years. Expansion of the heavy-
duty categories required more effort. Since MOBILES reports heavy-duty gasoline vehicle counts
and heavy-duty diesel vehicle counts separately, it was necessary to add these counts together to
get total heavy-duty vehicle counts for calendar years 1982 through 1990. These vehicle counts
were then split using the same class ratios used in this analysis for 1996 and later vehicle counts as
per Section 4.1.2.
Linear interpolation was used to fill in the data gap between the 1990 data in MOBILES
and the 1996 data used in this analysis. The results of these adjustments are contained in Appendix
D.
-35-
-------
5.0 Integration of Registration Distribution by Age, Average Annual Mileage
Accumulation Rates by Age, and Future Vehicle Count Data in MOBILE6
One of the most significant changes to the fleet characterization calculations from
MOBILES to MOBILE6 is an increase in the number of vehicle categories considered (from eight
to thirty). This change has been made both to facilitate greater representation of class-specific fleet
trends (i.e., differences between mileage accumulation in certain heavy-duty vehicle categories,
etc) and to allow for greater flexibility in future fleet calculations as additional data becomes
available.
The data that was used in this analysis, however, was not directly available for each of the
thirty vehicle classes. Hence, for many categories, it was necessary to apply the available data to
more than one vehicle class. The following sections will describe the thirty vehicle classes, and the
ways that fleet characterization data presented in the report will be used in the model.
5.1 Expansion of Vehicle Categories
In MOBILES, the eight vehicle categories considered separately were light-duty gasoline
vehicles, light-duty diesel vehicles, light-duty gasoline trucks 1 (0-6,000 Ibs GVWR), light-duty
gasoline trucks 2 (6,001-8,500 Ibs GVWR), light-duty diesel trucks (0-8500 Ibs GVWR), heavy-
duty gasoline vehicles, heavy-duty diesel vehicles, and motorcycles. The light-duty truck category
was split into trucks 1 and 2 to correspond with EPA regulatory definitions, which state different
emission standards for the two gross-vehicle weight categories. However, starting with a phase-in
period in 1994, EPA expanded its regulatory classifications to include four light-duty truck
categories. This change effectively increases the number of light-duty truck categories in the model
from two to eight. These categories are described in Appendix C in detail; Table 10 from Section
4.1.1. is reproduced here for reference. Note that these new categories apply to both gasoline- and
diesel-fueled light trucks.
Table 10. Description of New EPA Light-duty Truck Classifications
MOBILES Category
Light-duty truck 1
Light-duty truck 1
Light-duty truck 2
Light-duty truck 2
MOBILE6
Category
Light-duty truck 1
Light-duty truck 2
Light duty truck 3
Light duty truck 4
Gross Vehicle
Weight Rating
<6000 Ibs
<6000 Ibs
>6000 Ibs
>6000 Ibs
Loaded Vehicle
Weight Rating
< 3750 Ibs
>3750 Ibs
<5750 Ibs (Average
Loaded Vehicle
Weight)*
>5750 Ibs (Average
Loaded Vehicle
Weight)*
Description
Most small SUVs, most small pickups
All minivans, "Compact" SUVs (e.g., Explorer),
most Dakota and T100 pickups
Most 1/2-ton pickups, Base full-size vans, and
intermediate SUVs (e.g., Land Cruiser)
Some 1/2 and 3/4 ton pickups, some full-size
vans, and larger SUVs (e.g., Expedition)
* Average Loaded Vehicle Weight is the average of the gross vehicle weight and the curb weight
-36-
-------
In addition to including the new light-truck categories to MOBILE6, EPA has also
expanded the heavy-duty gasoline vehicle and heavy-duty diesel vehicle categories to include a
finer gradation by gross-vehicle weight class. The addition of new categories increases the total
number of heavy-duty categories from two to nineteen. Note that EPA has included only one
heavy-duty gasoline bus category. This is due to the fact that, according to the Arcadis report,
heavy-duty transit buses accounted for less than 1% of the all gasoline buses in 1996. EPA has
therefore grouped gasoline school buses into a single category, known as "heavy-duty gasoline
bus." Table 19 lists the new heavy-duty categories.
Table 19. Description of New EPA Heavy-duty Truck Classifications
MOBILE6
Categories
Heavy-duty gasoline vehicle class 2B
Heavy-duty gasoline vehicle class 3
Heavy-duty gasoline vehicle class 4
Heavy-duty gasoline vehicle class 5
Heavy-duty gasoline vehicle class 6
Heavy-duty gasoline vehicle class 7
Heavy-duty gasoline vehicle class 8A
Heavy-duty gasoline vehicle class 8B
Heavy-duty gasoline bus
Heavy-duty diesel vehicle class 2B
Heavy-duty diesel vehicle class 3
Heavy-duty diesel vehicle class 4
Heavy-duty diesel vehicle class 5
Heavy-duty diesel vehicle class 6
Heavy-duty diesel vehicle class 7
Heavy-duty diesel vehicle class 8A
Heavy-duty diesel vehicle class 8B
Heavy-duty diesel school bus
Heavy-duty diesel transit Bus
Gross Vehicle
Weight Ratings
8,501-10,000 Ibs
10,001-14,000 Ibs
14,001-16,000 Ibs
16,001-19,500 Ibs
19,501-26,000
26,001-33,000
33,001-60,000
>60,000
All
8,501-10,000 Ibs
10,001-14,000 Ibs
14,001-16,000 Ibs
16,001-19,500 Ibs
19,501-26,000
26,001-33,000
33,001-60,000
>60,000
All
All
-37-
-------
5.2 Use of Registration Distribution by Age and Average Annual Mileage Accumulation
by Age in MOBILE6
The emission factor calculations in MOBILE6 will rely in part on travel fractions for
vehicles at each of twenty-five ages and for each of the thirty vehicle types. These travel fractions
are calculated from estimates of the registration distribution by age (age 0-1 through age 30) and
average annual mileage accumulation rates by age for thirty vehicle types (registration distribution
and average annual mileage accumulation rates for motorcycles, are only provided for the first
through 12+ years of operation).
The registration distributions by age and average annual mileage accumulation rates by age
presented in Section 2.0 and Section 3.0 of this report represent the national defaults MOBILE6
will use for generation of travel fractions. However, as noted in these sections, there are only
seven categories for registration distributions by age, and only eighteen categories for average
annual mileage accumulation rates by age. Therefore, it was necessary to assume that the
estimated registrations distributions and mileage accumulation rates would be representative of
other categories. Table 16 illustrates the application of the calculated registration distribution by
age and average annual mileage accumulation rates by age to the thirty MOBILE6 categories. Note
that due to the lack of significant changes in the U.S. motorcycle age distribution, mileage
accumulation, and vehicle count characteristics, EPA has opted to use the MOBILES motorcycle
age and mileage estimates in MOBILE6. The MOBILES motorcycle data is reported in Appendix
A.
MOBILE6 will apply the gasoline/ diesel fuel ratios presented in Section 4.2 to the vehicle
counts to calculate fuel-specific vehicle counts by calendar year and vehicle class. The model will
assume that 50% of the HDV4-5 class should be attributed to classes 4 and 5 respectively; the
same assumption will be made for HDV6-7 vehicle counts. This is again due to the inability to
weight theses classes separately due to data constraints.
-38-
-------
Table 20. Use of Registration Distribution by Age, Mileage Accumulation, and Vehicle
Count Data in MOBILE6
MOBILE6 category description
MOBILE6 category
designation
Registration
Distribution
(Table 5)
Mileage
Accumulation
(Table 6)
Vehicle Counts
(Tables
13 and 17)
Gasoline Fueled Vehicles
Light-duty gasoline vehicle
Light-duty gasoline truck 1
Light-duty gasoline truck 2
Light-duty gasoline truck 3
Light-duty gasoline truck 4
Heavy-duty gasoline vehicle class 2B
Heavy-duty gasoline vehicle class 3
Heavy-duty gasoline vehicle class 4
Heavy-duty gasoline vehicle class 5
Heavy-duty gasoline vehicle class 6
Heavy-duty gasoline vehicle class 7
Heavy-duty gasoline vehicle class 8A
Heavy-duty gasoline vehicle class 8B
Heavy-duty gasoline Bus *
Motorcycle
LDGV
LDGT1
LDGT2
LDGT3
LDGT4
HDGV2B
HDGV3
HDGV4
HDGV5
HDGV6
HDGV7
HDGV8A
HDGV8B
HDGas Bus
Motorcycle
LDV
LOT 0-6000 Ibs
LOT 0-6000 Ibs
LOT 6000-8500 Ibs
LOT 6000-8500 Ibs
HDV (2B-3)
HDV (2B-3)
HDV (4-8)
HDV (4-8)
HDV (4-8)
HDV (4-8)
HDV (4-8)
HDV (4-8)
HDB School
MOBILES
LDGV
LDGT1
LDGT1
LDGT2
LDGT2
HDGV (2B-3)
HDGV (2B-3)
HDGV (4-8)
HDGV (4-8)
HDGV (4-8)
HDGV (4-8)
HDGV (4-8)
HDGV (4-8)
HDGB School
MOBILES
LDV
LDT1
LDT2
LDT3
LDT4
HDV2B
HDV3
!/2 HDV4-5
!/2 HDV4-5
!/2 HDV6-7
!/2 HDV6-7
HDV8A
HDV8B
HD School Bus
MOBILES
Diesel Fueled Vehicles
Light-duty diesel vehicle
Light-duty diesel truck 1
Light-duty diesel truck 2
Light-duty diesel truck 3
Light-duty diesel truck 4
Heavy-duty diesel vehicle class 2B
Heavy-duty diesel vehicle class 3
Heavy-duty diesel vehicle class 4
Heavy-duty diesel vehicle class 5
Heavy-duty diesel vehicle class 6
Heavy-duty diesel vehicle class 7
Heavy-duty diesel vehicle class 8A
Heavy-duty diesel vehicle class 8B
Heavy-duty diesel School Bus
Heavy-duty diesel Transit Bus
LDDV
LDDT1
LDDT2
LDDT3
LDDT4
HDDV2B
HDDV3
HDDV4
HDDV5
HDDV6
HDDV7
HDDV8A
HDDV8B
Diesel School Bus
Diesel Transit Bus
LDV
LDT1
LDT1
LDT2
LDT2
HDV (2B-3)
HDV (2B-3)
HDV (4-8)
HDV (4-8)
HDV (4-8)
HDV (4-8)
HDV (4-8)
HDV (4-8)
HDB School
HDB Transit
LDDV
LDDT1
LDDT1
LDDT2
LDDT2
HDDV (2B)
HDDV (2B)
HDDV (4-5)
HDDV (4-5)
HDDV (6-7)
HDDV (6-7)
HDDV (8A)
HDDV (8B)
HDDB School
HDDB Transit
LDV
LDT1
LDT2
LDT3
LDT4
HDV2B
HDV3
!/2 HDV4-5
!/2 HDV4-5
!/2 HDV6-7
!/2 HDV6-7
HDV8A
HDV8B
HD School Bus
HD Transit Bus
* Note: MOBILE6 will only contain one heavy-duty gasoline bus category; containing all heavy-duty gasoline buses.
-39-
-------
APPENDIX A: Motorcycle Age Distribution, Mileage Accumulation Rates, and Vehicle
Counts
-40-
-------
Motorcycle Age Distribution and Mileage Accumulation Rates for
Use in MOBILE6
Age
1
2
3
4
5
6
7
8
9
10
11
12+
Registration
Distribution
0.144
0.168
0.135
0.109
0.088
0.07
0.056
0.045
0.036
0.029
0.023
0.097
Mileage
Accumulation Rates
4,786
4,475
4,164
3,853
3,543
3,232
2,921
2,611
2,300
1,989
1,678
1,368
NOTE: Motorcycle vehicle count is 4,219,000 for all years, pre-1982 through 2050.
Source: 1987 Motorcycle Statistical Annual, Motorcycle Industry Council, Inc.
-41-
-------
APPENDIX B: Vehicles in Operation, Raw Mileage Accumulation Rate, and Curve Fitting
Equations from the Arcadis Report
-42-
-------
Table 4-2. Vehicles in Operation as of July 1996
U.S. Levels
Model
Year
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
TOTAL
LDV
LDGV
5999331
9166694
7966182
8027524
7468105
7742072
7927068
8687143
8800821
8403556
8093892
7090963
5978688
3831635
2710825
2305351
1953647
2237823
1785913
1335445
824579
477882
532240
0
0
0
0
0
0
0
0
119347379
LDDV
5330
5425
630
2715
4432
9746
3280
3676
568
23000
26380
69659
98664
94461
145689
175194
79200
61862
20597
12593
11453
7505
3599
0
0
0
0
0
0
0
0
865658
LDGT
LDGT1
<6000
2475332
3723979
3636380
3338741
2716821
2893672
2517145
2922994
2961942
2666470
2600147
2040755
1670540
948999
739107
651163
446378
529703
384720
328772
389724
210964
335900
0
0
0
0
0
0
0
0
41130348
LDGT2
6001-8500
963616
1450819
1214578
855812
748099
570854
712943
833087
737315
576923
701241
661168
564080
388127
277091
251737
340398
820584
756833
587410
295581
181913
130161
0
0
0
0
0
0
0
0
14620369
LDDT
LDDT1
<6000
0
0
1
0
0
0
0
0
0
1937
8701
9754
20230
21601
51916
42762
20482
17283
10222
0
7408
24441
44505
0
0
0
0
0
0
0
0
281243
LDDT2
6001-8500
12298
16827
13634
12582
8703
7481
6943
6934
5338
4760
8808
9038
9680
8271
7279
329
217
917
93
21
12
8
7
0
0
0
0
0
0
0
0
140179
HDGV
2B-3
8501-14000
321205
483606
404859
285271
249366
190285
237648
277696
245772
192308
233747
220389
188027
129376
92364
83912
113466
273528
252278
195803
98527
60638
43387
0
0
0
0
0
0
0
0
4873456
4-8
>14000
16273
54732
47587
35154
36885
35345
47336
55083
70682
58113
51373
56147
55959
37983
37446
37952
45494
88619
69373
67918
67102
90069
94921
93372
72328
54597
57955
50761
39588
38887
34371
1699401
HDGB
S.BUS
ANYWGT.
516
4408
2926
2673
102
2368
4009
4342
6115
6980
8209
11009
11363
10931
9270
12053
10434
9290
8459
9547
6915
8715
0
0
0
0
0
0
0
0
0
150634
T.BUS
ANYWGT.
0
0
30
54
108
83
55
116
78
84
87
28
34
23
11
4
9
13
2
1
2
3
1
0
0
0
0
0
0
0
0
826
LDV Light duty vehicle
LDGV Light duty gasoline vehicle
LDDV Light duty diesel vehicle
LDGT Light duty gasoline truck
LDDT Light duty diesel truck
HDGV Heavy duty gasoline vehicle
HDGB Heavy duty gasoline bus
Table 4-2. Vehicles in operation as of July 1996 (continued)
U.S. Levels
-43-
-------
Model
Year
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
TOTAL
HDDV
2B
8501-10000
77760
162857
131869
133923
93290
77685
72117
69774
50752
45383
84934
80761
78286
51681
35845
1135
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1248050
3
10001-14000
20611
49894
46825
37278
31827
28002
40421
32708
22387
20704
25966
10736
6075
4005
2110
21
0
0
1
2
3
5
34
20
0
0
0
0
0
0
4
379639
4-5
14001-19500
15084
45619
29457
26359
20855
14467
18977
20834
13770
4064
2184
2066
1565
454
198
246
2
0
0
0
268
106
6
127
118
60
38
116
95
94
71
217303
6-7
19501-33000
36848
112777
69815
63675
55070
64578
80650
60814
68499
69454
60684
61696
56347
28033
29110
39861
27106
23784
14891
7938
4459
4534
3740
3497
2601
1905
4447
2618
2007
321
261
1062021
8A*
33001-60000
22858
55767
41561
35682
18191
25051
28786
29759
25953
29736
28204
30539
25970
13613
18921
23076
19685
28160
21616
14940
9327
15695
5779
5492
4445
3799
3386
850
655
186
277
587955
8B*
>60000
63398
154674
115272
98966
79092
71036
83175
98894
89567
74622
59103
69423
56621
26483
28273
33078
24454
36212
29266
23464
9767
10430
8590
7013
3650
1980
791
1205
605
946
298
1360346
HDDB
S.BUS
ANYWGT.
12592
34395
17088
19899
20696
24920
28698
15007
18602
19539
17097
11743
7120
5245
4488
4324
659
448
253
235
60
77
0
0
0
0
0
0
0
0
0
263185
T.BUS**
ANYWGT.
1186
2496
2278
3188
4682
3829
3167
3299
3330
3741
3206
3989
3017
3270
3811
1695
1182
760
510
682
338
393
247
211
73
106
78
90
189
55043
ALL
VEHICLES
TOTAL
10043049
15522473
13739879
12978803
11553918
11760833
11813932
13122690
13121329
12200932
12014086
10439615
8832456
5604910
4192960
3665466
3085441
4129922
3355700
2584847
1725698
1093667
1203209
109914
83389
62551
66691
55655
43028
40524
35470
188283036
HDDV
HDDB
Heavy duty diesel vehicle
Heavy duty diesel bus
* in MY 93-96, assumed 26.5% of Class 8 vehicles are Class 8A; for all other MY, percentage based upon
1992 Tl US data
** transit bus registrations are from FTA data
-44-
-------
Table 4-5. Annual mileage accumulation curve fit equations
Vehicle Class
LDGV
LDDV
LDGT1
LDGT2
LDDT1
LDDT2
HDGV (2B-3)
HDGV (4-8)
HDGSB
HDGTB
HDDV(2B)
HDDV(3)
HDDV (4-5)
HDDV (6-7)
HDDV (8A)
HDDV(8B)
HDDSB
HDDTB
Equation
y = 1 56846'° 0506x
y = 1 56846'° 0506x
y= 1 7.472x2-1 163. 7x+ 20642
y = 22905e-°0712x
y = 300286'° 1041x
y = 28231e-°0808x
y = 21250e-°0618x
y = 23243e-°0829x
y = 9939
y = 38654e-°0958x
y = 29657e-°0888x
y = 37008e-° 1222x
y = 32635e-°0656x
y = 44883e-°0983x
y = 98554e-°1153x
y=137024e-°0982x
y = 9939
y = 46659e-°0324x
x = Model year -1900
y = Annual mileage (miles)
-45-
-------
APPENDIX C: Federal Definitions for Light-duty Vehicles
-46-
-------
FEDERAL DEFINITIONS OF LIGHT-DUTY VEHICLES
Light-Duty Truck (LDT)
Any motor vehicle rated at 8,500 pounds GVWR or less which has a vehicle curb weight of 6,000 pounds
or less and which has a basic vehicle frontal area of 45 square feet or
less, which is:
(1) Designed primarily for purposes of transportation of property or is a derivation of such a vehicle, or
(2) Designed primarily for transportation of persons and has a capacity of more than 12 persons, or
(3) Available with special features enabling off-street or off-highway operation and use. (40 CFR 86.082-2)
Light Light-Duty Truck (LLDT)
Light light-duty truck means any light-duty truck rated up through 6,000 Ibs GVWR. (40 CFR 86.094-2)
[Note: The definition for this category of trucks is essentially identical to the California definition for
"light-duty truck.")
Heavy Light-Duty Truck (HLDT)
Heavy light-duty truck means any light-duty truck rated greater than 6,000 Ibs GVWR. (40 CFR 86.094-2)
Light-Duty Truck 1 (LDT1)
Any light light-duty truck up through 3,750 Ibs loaded vehicle weight. (40 CFR 86.094-2)
Light-Duty Truck 2 (LDT2)
Any light light-duty truck greater than 3,750 Ibs loaded vehicle weight. (40 CFR 86.094-2)
Light-Duty Truck 3 (LDT3)
Any heavy light-duty truck up through 5,750 Ibs adjusted loaded vehicle weight. (40 CFR 86.094-2)
Light-Duty Truck 4 (LDT4)
Any heavy light-duty truck greater than 5,750 Ibs adjusted loaded vehicle weight. (40 CFR 86.094-2)
Light-Duty Vehicle (LDV)
A passenger car or passenger car derivative capable of seating 12 passengers or less.
[Note: The federal "light-duty vehicle" definition is essentially identical to the California definition for
"passenger car."]
Loaded Vehicle Weight (LVW)
The vehicle curb weight plus 300 pounds. (40 CFR 86.082-2)
-47-
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APPENDIX D: Complete Tables of Vehicle Counts, pre-1982-2050
-48-
-------
LIGHT-DUTY VEHICLE CLASS VEHICLE COUNTS, PRE-1982 THROUGH 2050
From MOBILES
Interpolated <
Arcadis Report
Calculated
Calendar Year
pre-1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020 - 2050
Light-duty
Vehicles
106,867,000
108,960,000
112,018,000
114,662,000
117,268,000
119,849,000
121,519,000
122,758,000
124,658,000
123,917,173
123,176,346
122,435,519
121,694,691
120,953,864
120,213,037
118,773,800
117,096,045
115,193,551
113,163,114
112,067,320
110,950,294
109,439,432
107,898,603
105,955,155
103,575,222
101,040,538
98,431,413
96,043,330
93,587,131
91,290,697
89,345,016
87,503,888
85,917,827
84,384,402
82,971,891
81,805,681
80,793,310
79,950,083
79,436,359
Light-duty
Truck Class 1
4,801,335
4,857,006
5,065,830
5,336,562
5,676,594
6,006,462
6,343,260
6,759,984
7,058,898
7,495,735
7,932,572
8,369,409
8,806,246
9,243,083
9,566,078
10,414,527
11,280,465
12,162,938
13,070,784
13,799,291
14,512,453
15,274,865
16,025,634
16,685,013
17,410,842
18,155,682
18,906,365
19,613,047
20,228,884
20,817,379
21,346,077
21,856,971
22,324,492
22,695,902
23,052,159
23,371,618
23,669,750
23,943,693
24,165,899
Light-duty
Truck Class 2
15,983,665
16,168,994
16,864,170
17,765,438
18,897,406
19,995,538
21,116,740
22,504,016
23,499,102
24,953,334
26,407,567
27,861,799
29,316,031
30,770,263
31,845,513
34,670,004
37,552,716
40,490,475
43,512,698
45,937,900
48,312,019
50,850,090
53,349,406
55,544,480
57,960,767
60,440,343
62,939,370
65,291,919
67,342,044
69,301,145
71,061,181
72,761,950
74,318,331
75,554,755
76,740,738
77,804,216
78,796,699
79,708,656
80,448,384
Light-duty
Truck Class 3
6,969,875
7,154,140
7,495,270
7,676,795
8,141,910
8,480,985
9,159,820
9,548,900
9,640,005
9,662,236
9,684,467
9,706,698
9,728,929
9,751,160
10,110,975
11,007,753
11,923,017
12,855,757
13,815,316
14,585,319
15,339,104
16,144,943
16,938,478
17,635,416
18,402,589
19,189,856
19,983,299
20,730,235
21,381,152
22,003,168
22,561,981
23,101,976
23,596,128
23,988,694
24,365,244
24,702,900
25,018,014
25,307,561
25,542,425
Light-duty
Truck Class 4
3,205,125
3,289,860
3,446,730
3,530,205
3,744,090
3,900,015
4,212,180
4,391,100
4,432,995
4,443,218
4,453,441
4,463,664
4,473,887
4,484,110
4,649,573
5,061,960
5,482,847
5,911,772
6,353,028
6,707,118
7,053,749
7,424,317
7,789,227
8,109,717
8,462,504
8,824,532
9,189,400
9,532,882
9,832,208
10,118,245
10,375,217
10,623,537
10,850,774
11,031,297
11,204,455
11,359,728
11,504,634
11,637,783
11,745,787
Light-duty
Total
137,827,000
140,430,000
144,890,000
148,971,000
153,728,000
158,232,000
162,351,000
165,962,000
169,289,000
170,471,696
171,654,392
172,837,088
174,019,784
175,202,480
176,385,176
179,928,044
183,335,089
186,614,492
189,914,940
193,096,949
196,167,619
199,133,647
202,001,349
203,929,782
205,811,924
207,650,951
209,449,847
211,211,414
212,371,419
213,530,633
214,689,471
215,848,322
217,007,553
217,655,051
218,334,488
219,044,142
219,782,406
220,547,776
221,338,854
-49-
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HEAVY-DUTY VEHICLE CLASS VEHICLE COUNTS, PRE-1982 THROUGH 2050
From MOBILES^
Interpolated O
Arcadis Report <
Calculated
Calendar Year
pre-1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020-2050
2B
3,025,472
3,350,257
3,650,445
4,056,552
4,200,622
4,498,300
4,714,656
5,018,358
5,173,471
5,306,653
5,439,835
5,573,017
5,706,199
5,839,381
5,972,563
6,234,738
6,495,685
6,755,458
6,929,009
7,103,086
7,277,658
7,452,698
7,628,181
7,729,717
7,834,765
7,943,097
8,054,502
8,168,782
8,226,408
8,289,920
8,358,898
8,432,953
8,511,724
8,553,232
8,601,538
8,656,127
8,716,524
8,782,288
8,853,014
3
267,759
296,503
323,071
359,012
371,762
398,107
417,255
444,133
457,861
469,648
481,435
493,222
505,008
516,795
528,582
551,785
574,879
597,870
613,229
628,635
644,085
659,576
675,107
684,093
693,390
702,978
712,837
722,951
728,051
733,672
739,777
746,331
753,302
756,976
761,251
766,082
771,427
777,247
783,507
4
198,290
219,576
239,251
265,867
275,310
294,819
308,999
328,904
339,070
347,799
356,528
365,257
373,985
382,714
391,443
408,626
425,728
442,754
454,129
465,538
476,979
488,451
499,952
506,607
513,492
520,592
527,894
535,383
539,160
543,323
547,844
552,697
557,860
560,580
563,746
567,324
571,283
575,593
580,228
5
176,578
195,534
213,054
236,756
245,164
262,538
275,165
292,891
301,944
309,717
317,490
325,263
333,036
340,809
348,582
363,883
379,113
394,274
404,404
414,563
424,752
434,968
445,210
451,136
457,267
463,590
470,092
476,761
480,125
483,832
487,857
492,180
496,777
499,199
502,019
505,205
508,730
512,568
516,696
6
551,683
610,907
665,645
739,697
765,968
820,248
859,700
915,079
943,363
967,648
991,933
1,016,219
1,040,504
1,064,789
1,089,074
1,136,881
1,184,464
1,231,832
1,263,479
1,295,221
1,327,053
1,358,971
1,390,970
1,409,485
1,428,640
1,448,394
1,468,708
1,489,547
1,500,055
1,511,636
1,524,214
1,537,717
1,552,081
1,559,650
1,568,458
1,578,412
1,589,425
1,601,417
1,614,314
7
581,388
643,800
701,486
779,525
807,210
864,414
905,989
964,350
994,158
1,019,750
1,045,343
1,070,936
1,096,529
1,122,122
1,147,715
1,198,095
1,248,240
1,298,159
1,331,510
1,364,961
1,398,507
1,432,144
1,465,865
1,485,377
1,505,564
1,526,381
1,547,789
1,569,750
1,580,824
1,593,028
1,606,283
1,620,514
1,635,651
1,643,628
1,652,910
1,663,400
1,675,006
1,687,644
1,701,235
8A
298,804
330,880
360,528
400,636
414,865
444,264
465,632
495,627
510,946
524,099
537,253
550,406
563,560
576,713
589,867
615,760
641,531
667,187
684,328
701,520
718,761
736,049
753,380
763,408
773,783
784,482
795,484
806,771
812,462
818,735
825,547
832,861
840,641
844,740
849,511
854,903
860,868
867,363
874,348
8B
689,099
763,074
831,447
923,944
956,758
1,024,559
1,073,838
1,143,011
1,178,340
1,208,675
1,239,009
1,269,343
1,299,677
1,330,012
1,360,346
1,420,060
1,479,495
1,538,663
1,578,192
1,617,840
1,657,602
1,697,470
1,737,439
1,760,566
1,784,492
1,809,166
1,834,541
1,860,570
1,873,695
1,888,161
1,903,872
1,920,739
1,938,680
1,948,134
1,959,137
1,971,570
1,985,327
2,000,305
2,016,414
School Bus
209,625
232,128
252,927
281,065
291,047
311,672
326,663
347,705
358,453
367,680
376,908
386,136
395,364
404,591
413,819
431,984
450,064
468,063
480,088
492,149
504,245
516,373
528,531
535,566
542,845
550,351
558,070
565,988
569,980
574,381
579,160
584,291
589,749
592,625
595,972
599,754
603,939
608,495
613,396
Transit Bus
28,301
31,339
34,147
37,946
39,294
42,078
44,102
46,943
48,394
49,640
50,886
52,132
53,377
54,623
55,869
58,321
60,762
63,192
64,816
66,444
68,077
69,715
71,356
72,306
73,289
74,302
75,344
76,413
76,952
77,546
78,191
78,884
79,621
80,009
80,461
80,972
81,537
82,152
82,814
Heavy-duty Total
6,027,000
6,674,000
7,272,000
8,081,000
8,368,000
8,961,000
9,392,000
9,997,000
10,306,000
10,571,310
10,836,620
11,101,930
11,367,239
11,632,54
11,897,859
12,420,134
12,939,962
13,457,453
13,803,182
14,149,957
14,497,720
14,846,415
15,195,992
15,398,261
15,607,525
15,823,332
16,045,260
16,272,915
16,387,713
16,514,234
16,651,644
16,799,168
16,956,086
17,038,774
17,135,004
17,243,750
17,364,065
17,495,073
17,635,965
-50-
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REFERENCES
1. Browning, Louis, et al. Update of Fleet Characterization Data for Use inMOBILE6: Final
Report. EPA Report # EPA420-P-98-016. Arcadis Geraghty & Miller, Mountain View, CA,
1998.
2. Office of Air and Radiation, Office of Mobile Sources, Engine Programs and Compliance
Division. Final Regulatory Impact Analysis: Control of Emissions of Air Pollution from
Highway Heavy-duty Engines. EPAReport # A-95-27, V-B-01. U.S. Environmental Protection
Agency, Ann Arbor, MI, 1997.
3. Office of Air and Radiation, Office of Mobile Sources. 1998 sales data as reported by
automotive manufacturers to the Vehicle Programs and Certification Division (VPCD)
Certification and Fuel Economy Information System (CFEIS) database. U.S. Environmental
Protection Agency, Ann Arbor, MI, 1998.
4. Energy Information Administration. Annual Energy Outlook 1999. U. S. Department of
Energy, Washington, D.C., 1999.
5. Pemberton, Max. 1996 World Vehicle Forecasts and Strategies: The Next 20 years: A
Special Report Covering the Period from 1960 - 2015. Ward's Communications. Pemberton
Associates, Warwickshire, UK, 1996.
6. German, John. VMT and Emission Implications of Growth in Light Truck Sales. Proceeding
of the 1997 Air & Waste Management Association conference, "Emission Inventory: Planning
for the Future." Air & Waste Management Association, Pittsburgh, PA, 1998.
7.Koupal, John W. Development of Light-duty Emission Inventory Estimates in the Notice of
Proposed Rulemaking for Tier 2 and Sulfur Standards. EPA Report# 420-R-99-005. U.S.
Environmental Protection Agency, Ann Arbor, MI, 1999.
8. Office of Air and Radiation, Office of Mobile Sources. 1998 sales data as reported by
automotive manufacturers to the Vehicle Programs and Certification Division (VPCD)
Certification and Fuel Economy Information System (CFEIS) database. U.S. Environmental
Protection Agency, Ann Arbor, MI, 1998.
9.Sienicki, Edward. Memo to Mr. Phil Lorang, of the U.S. Environmental Protection Agency
from Navistar International Transportation Corporation, data April 23, 1992.
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