EPA-AA-TEB-EF-84-2
Fleet Characterization Data Used for MOBILES
August 1984
Test and Evaluation Branch
Emission Control Technology Division
Office of Air and Radiation
U. S. Evironmental Protection Agency
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Table of Contents
1.0 INTRODUCTION
2.0 REGISTRATION DISTRIBUTIONS
2.1 Light-Duty Gasoline & Diesel Vehicles
2.2 Light-Duty Gasoline & Diesel Trucks
2.3 Heavy-Duty Gasoline Vehicles
2.4 Heavy-Duty Diesel Vehicles
3.0 MILEAGE ACCUMULATION RATES
3.1 Light-Duty Gasoline Vehicles
3.2 Light-Duty Diesel Vehicles
3.3 Light-Duty Gasoline & Diesel Trucks
3.4 Heavy-Duty Gasoline Vehicles
3.5 Heavy-Duty Diesel Vehicles
4.0 TOTAL VEHICLE COUNTS
References
Appendix 1. MOBILES July 1 Registration Distributions
Appendix 2. MOBILE3 Gasoline/Diesel Sales Fractions for LDVs and LDTs
Appendix 3. Annual Average Mileage Accumulation Rates for LDVs
Appendix 4. Annual Average Mileage Accumulation Rates for LDTs
Appendix 5. Annual Average Mileage Accumulation Rates for HDGVs
Appendix 6. Annual Average Mileage Accumulation Rates for HDDVs
Appendix 7. Total HDDV Registrations by Class for 1980 through 2000
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1.0 INTRODUCTION
The fleet characterization data in MOBILES are used primarily to weight
emission rates for different age groups of vehicles into fleet values.
The fleet characterization data consist of:
0 registration distributions by age
0 average annual mileage accumulation rates by age
0 gasoline/diesel sales fractions
0 total vehicle counts by class
The first two pieces of information are used to obtain the percent of
fleet vehicle-miles-traveled (VMT) accumulated by a given vehicle type
for a particular age. These are referred to as the travel fractions.
The average annual mileage accumulations are also used with the emission
deterioration rates and their zero mile emission levels to estimate the
emission rates of a given vehicle type for a given calendar year. Both
the registration distributions and mileage accumulation rates are part of
the MOBILE2/MOBILES input parameters. National average values are
assigned within the computer program, or they may be altered by user
supplied rates.
Because there have not been significant sales of light-duty diesel
vehicles and trucks until recent years, these vehicles are combined with
the gasoline vehicles and trucks in developing registration
distributions. The resulting distributions are for all light-duty
vehicles and light-duty trucks, irrespective of whether they are gasoline
or diesel powered. However, as gasoline powered vehicles and trucks have
different emission rates than the diesel powered vehicles and trucks,
these combined registration distributions must be split into separate
gasoline and diesel distributions. This task is accomplished by using
the gasoline/diesel sales fractions.
The vehicle counts by class are used along with other information, such
as average annual mileage traveled by vehicles in each vehicle class and
the percentage of vehicles which are diesel powered to yield • the
percentage of total mobile source VMT accumulated by a particular vehicle
class. These percentages are used in turn to determine an "all mobile
sources combined" emission factor.
One basic assumption of the emission estimation model regarding the fleet
characterization data is that all vehicles are sold, scrapped, and
accumulate mileages uniformly across all calendar years. Therefore,
it is important that both the registration distributions and the annual
The one exception is the mileage accumulation rates for heavy-duty
diesel vehicles. This is explained in section 3.5.
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mileage accumulation rates reflect the general trends of the vehicles'
age distributions and travel patterns. EPA contracted with Energy and
Environmental Analysis, Inc. (EEA) to determine how the fleet
characterization data may have changed since MOBILE2. Their final report
(Ref. 1, hereafter referred to as the 1983 EEA report) contains
estimations of registration distributions and mileage accumulation rates
based upon more recently available data. Most of the fleet
characterization data used for MOBILES are, at least in part, based upon
the updated estimates.
The purpose of this report is to summarize all the July 1 fleet
characterization data used for MOBILES. The MOBILES computer program
uses the same methodologies as MOBILE2 to transform the July 1
information to January 1' data. This report will limit its discussions to
the July 1 fleet characterization data only. Detailed discussion on how
the fleet characterization data are used by the MOBILE2 (or MOBILES)
computer program are contained in the document "Compilation of Air
Pollutant Emission Factors: Highway Mobile Sources" (Ref. 2)2. A new
compilation document on MOBILES is scheduled to be released in October,
1984.
Discussions on the calculation of the VMT mix are in Appendix B. The
January 1 transformations and travel weighting fraction calculations
are in Appendix D.
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2.0
REGISTRATION DISTRIBUTIONS
In the mobile source emission models, there are eight vehicle types for
which the registration fractions by age are required. These vehicle
types are shown in Table 1.
Table 1
Vehicle Classes in MOBILE2/MOBILE3
Vehicle Type Abbr.
Light-Duty Gasoline Vehicles LDGV
Light-Duty Diesel Vehicles LDDV
Light-Duty Gasoline Class 1 Trucks LDGT1
Light-Duty Gasoline Class 2A Trucks LDGT2
Light-Duty Diesel Trucks LDDT
Heavy-Duty Gasoline Vehicles HDGV
Heavy-Duty Diesel Vehicles HDDV
Motorcycles MC
Gross Vehicle
Weight (in Ibs)
0-6,000
6,001-8,500
0-8,500
more than 8,500
more than 8,500
Although it is possible to develop registration distributions for the
LDDVs and LDDTs from historical data, these distributions are probably
not representative of future registration distributions since there were
very few light-duty diesel sales before the year of 1975. Therefore, the
LDDV and LDDT distributions were estimated from the combined light-duty
vehicle and truck registration distributions and the expected
gasoline/diesel sales fractions. For HDVs, there were enough sales in
both the gasoline and diesel classes to estimate separate registration
distributions. Therefore, in MOBILE2/MOBILES, the registration fractions
are given for five vehicle types: LDVs, LDTs, HDGVs, HDDVs, and MCs.
The MOBILE2 registration distributions were based upon vehicle counts by
model year (age) in a given calendar year, that is, the LDV and LDT
registrations were from calendar year 1978 counts (Ref. 3) and the HDV
registrations were from calendar year 1972 counts. This has created some
problems. When a registration distribution is based upon counts from a
single calendar year, it incorporates the sales trends and scrappage that
exist at that time. These sales and scrappage trends may not be
appropriate for all other calendar years. For example, since the sales
of LDVs and LDTs were relatively high around the year of 1978, the
registration distributions developed from these data weighted newer (and,
from an emissions standpoint, cleaner) vehicles more, and older (dirtier)
vehicles somewhat less. In fact, the sales of LDGT2s were very high
during the 1975-78 time frame. Therefore, when emission estimates of
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LDGTls and LDGTZs were made for the 1985 and later time frames, the
LDGT2s were projected to have lower emissions than the LDGTls because of
the heavier weighting toward the newer model years (and lower
emissions). To eliminate or reduce these types of problems in MOBILES,
registration distributions were based upon two nonadjacent calendar years
of historical data.
Table 2 is a summary of the data base references for registration
distributions used for MOBILE2 and MOBILES. No update has been done for
the motorcycle (MC) registration distributions.
Table 2
References for Registration Distributions
Vehicle Class MOBILES MOBILE2
LDVs 1977 & 1981 R.L. Polk 1978 R.L. Polk
LDTs 1978 & 1981 R.L. Polk 1978 R.L. Polk
HDVs 1972 TIUS* & 1981 Polk 1972 TIUS
* Truck Inventory and Use Survey, U.S. Department of Commerce, Bureau
of the Census.
The method used to develop a registration distribution from two
representative calendar years' data was to derive a density function that
excluded the age 1 and age 20 plus fractions. Age 1 data were excluded
because the surveys of vehicle counts by age take place in July, and the
age 1 (current model year) vehicles have not all been included in these
counts. Age 20 plus data were excluded because registrations for
vehicles older than 19 years of age are added up to be the age 20 plus
registration. Therefore, by excluding the ages 1 and 20 plus data, a
general trend of vehicle registrations can be better characterized. With
the density function (either a linear or an exponential) that fits the
data the best, a set of predicted fractions for ages 2 through 19 can
thus be derived. It should be noted that the registration of vehicles
decreasing as the age of vehicles increases. For example, the age 10
vehicle fraction is expected to be lower than the fraction of registered
age 9 vehicles, and higher than the fraction of registered age 11
vehicles.
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The age 1 fractions were then estimated from the age 2 fractions by
applying an adjustment factor. For LDVs and LDTs the adjustment factor
is 0.75, since the sales of LDVs and LDTs are assumed to begin in October
of the previous year and the surveys of vehicle counts take place in
July. The adjustment factor for HDVs is 0.50, due to the fact that sales
of HDVs are assumed to begin in January and the July 1 information will
account for half year vehicle fractions. The age 20 plus fractions were
the sum of the extrapolated values from ages 20 and up. Therefore, the
age 20 plus registration is expected to be a little higher than the value
predicted for age 19.
The set of smoothed fractions was then renormalized. The resulting
MOBILES July 1 registration distributions are tabulated in Appendix 1.
Note that the LDGV distributions are used for both LDGVs and LDDVs. In
addition, the fractions from LDGTls are used for all LDTs, explained
further in Section 2.2.
The gasoline and diesel sales fractions for LDVs and LDTs (given in
Appendix 2) are used in MOBILE2 /MOBILES to split the LDV and LDT
registration distributions into gasoline and diesel registration
distributions. The sales fractions of diesel and gasoline HDVs are not
listed due to the fact that separate registration distributions for HDGVs
and HDDVs are already available.
2.1 Light-Duty Gasoline and Diesel Vehicles
The 1983 EEA final report tabulated LDV registration distributions for
calendar years 1976 through 1982 (Table 3-1 of the 1983 EEA report).
These fractions were generated from R. L. Polk data. These seven year
fractions were used as data base for curve-fitting, using the same
methodology described in Section 2.0. The resulting set of registration
distributions is very similar to that obtained from using only the 1977
and 1981 data. This is due to the fact that during this seven year
period, 1977 had the best vehicle sales (8,497,893 units), while 1981
held the worst sales record on light-duty vehicles (6,253,138 units). By
using only the 1977 and 1981 data, the registration distributions would
capture the fluctuations of the economic situation. This is the data
base used for MOBILES.
A linear density function was found to result in a better fit than an
exponential curve. The predicted fractions from an exponential curve
exhibited unrealistically high fractions for ages 2 through 4 vehicles.
On the other hand, the fitted linear function had such a rapid decreasing
rate that the predicted fractions reached zero at the age of 19. This
would imply that the LDVs are no longer in use after they are 18 years of
age — an assumption contrary to reality. Therefore, for ages 17 and up,
averaged values from the 1977 and the 1981 data were used to replace the
predicted fractions.
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The renormalized fractions were used for MOBILES LDV registration
distributions. Figure 1 is a pictorial view of the four sets of
registration distributions: one that was used for MOBILE2 (1978 data),
one that came from the 1977 data, one that was obtained from the 1981
data, and one that combined the 1977 and 1981 data sets (used for
MOBILE3).
2.2 Light-Duty Gasoline and Diesel Trucks
MOBILE2 used separate registration distributions for light duty class 1
and class 2A trucks. However, using separate registration distributions
for LDGTls and LDGT2s presented a problem in MOBILE2, as discussed in
section 2.0. The emission standards for LDGT2s have been the same as
those for LDGTls since 1979. The sales of LDGT2s have also stabilized so
that the 1975-78 sales of LDGT2s should be viewed as a one-time
occurrence. To avoid the problem of heavier weighting on newer model
years, a separate LDGT2 registration distribution was not used in
MOBILES. Because of the similarities in vehicle weight classes and uses
(personal transportation and light hauling), the LDGT1 registration
distribution was used for LDGT2s.
There have not been enough diesel truck sales in past years to estimate
the LDDT registration distribution. MOBILE2 used the LDGT1 registration
distributions to represent both the gasoline class 1 and diesel trucks.
This was also done in MOBILES.
The LDGT1 fractions from the 1978 data (used in MOBILE2) and those from
the 1981 data are the data base used for MOBILES. The curve-smoothing
technique discussed in Section 2.0 was used. A linear density function
was found to be a more reasonable fit than an exponential curve. The
exponential curve for this data set had such a small decreasing rate that
the fraction value for age 20 plus was calculated to be higher than
the predicted fractions for any other age. Therefore, a linear function
was used to smooth the LDGT1 registration distribution. The renormalized
registration distribution, together with those from the 1978 (MOBILE2)
and the 1981 data, are shown in Figure 2.
As described in Section 2.0, the prediction on age 20 plus was the
sum of the extrapolated fractions from age 20 and up, until the
fractions reached zero.
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2.3 Heavy-Duty Gasoline Vehicles
The most recently available HDGV registration data were found in the 1981
Polk data (Table 3-19 of the 1983 EEA report). Fractions developed from
this data and the 1972 TIUS data (used in MOBILE2) are used as the data
base for MOBILES. An exponential function is used to smooth the data.
The renonnalized fractions are the registration distribution used for
MOBILES. The three sets of fractions, one from the 1972 data (used in
MOBILE2), one from the 1981 data, and the one that is used for MOBILES,
are shown in Figure 3.
2.4 Heavy-Duty Diesel Vehicles
The most recently available HDDV registration data were also found in the
1981 Polk data (Table 3-18 of the 1983 EEA report). Fractions developed
from this data and the 1972 TIUS data (used in MOBILE2) are used as the
data base for MOBILES. An exponential function is used to smooth the
data.
The renonnalized fractions are the registration distribution for
MOBILES. The three- sets of fractions, one from the 1972 data (used in
MOBILE2), one from the 1981 data, and the one that is used for MOBILES,
are shown in Figure 4.
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3.0 MILEAGE ACCUMULATION RATES
The MOBILES mileage accumulation rates are different from the MOBILE2
rates in three aspects:
1. The MOBILES rates are based upon more recent data, estimated
from different or updated surveys. Data source differences are
summarized in Table 3.
Table 3
References for Mileage Accumulation Rates
Vehicle Class MOBILES MOBILE2
LDGV 1979 GMR-NPD* 1978 NTS**
LDDV same as LDGV same as LDGV
LDGT1 1977 TIUS*** 1972 TIUS
LDGT2 1977 TIUS 1972 TIUS
LDDT 1977 TIUS 1972 TIUS
HDGV 1977 TIUS 1972 TIUS
HDDV 1977 TIUS 1972 TIUS
* General Motors Research Laboratories (GMR) derived these data from
National Purchase Diary Research, Inc. (NPD) survey.
** National Transportation Survey (for National Science Foundation).
*** Truck Inventory and Use Survey, U.S. Department of Commerce, Bureau
of the Census.
2. The average annual mileage accumulations of a given vehicle
type are smoothed by fitting the data with an exponential function. The
predicted values of the fitted data are used in MOBILES. The MOBILE2
model used unsmoothed data.
3. The HDDV rates in MOBILE2 were the averages over all weight
classes for trucks above 8,500 Ibs GVW. The MOBILES model used the
mileage distributions weighted by the projected registrations of four
different HDDV classes. (The derivation on HDDV mileage accumulation
rates will be discussed in section 3.5.).
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The curve-smoothing methodology used for mileage accumulation rates is
slightly different from that used for registration distributions. All
data points were included in the curve fitting process. The mileage
accumulation rates for all vehicle types, except motorcycles, were the
predicted values from fitting an exponential function.
The mileage accumulation rates used for MOBILES are tabulated in
Appendices 3 through 6. The MOBILE2 rates are also listed for comparison
purposes. Since no update has been done for the motorcycle mileage
accumulation rates, they are not listed in this report.
3.1 Light-Duty Gasoline Vehicles
In the MOBILE2 model, the annual average mileage accumulation rates for
LDGVs were based upon the 1978 National.Transporation Survey (NTS) data
(Ref. 4). The 1983 EEA report used data from the 1981 National Purchase
Diary Research, Inc. (NPD) survey. However, the purpose of this NPD
survey was mainly to characterize household fuel purchases and their
travel patterns. The survey results were criticized for not including
singles or families that lived in apartments, boarding rooms, or
condominiums. Consequently, estimates from this data set were considered
to be biased. For this reason, results from the 1983 EEA report were not
used.
The 1977 Nationwide Personal Transporation Study (NPTS) data were used as
the data base for the draft version4 of MOBILES. Only the first ten
year data were available. These ten year data were used for an
exponential fit. The mileage accumulation rates for vehicles eleven
years of age and up were extrapolated from the first ten year data.
In the final version of MOBILES, however, the LDGV mileage accumulation
rates were based upon a special 1979 NPD survey. Motor Vehicle
Manufacturer's Association (MVMA), in their comments on the MOBILES
Draft, suggested that the 1977 NPTS data might also be biased. Since the
NPTS data were based upon subjective car owner responses about vehicle's
mileage during a given year, rather than the actual odometer readings,
the results from the NPTS data might over-estimate the annual mileage (as
the respondents tended to round the annual mileage to 10,000 miles). The
1979 NPD survey data, on the other hand, were based upon actual odometer
readings. Furthermore, GM contracted with NPD to include 460
single-person households in this data base. The mileage accumulation
rates estimated from this data base may be less biased and be a better
reflection of actual travel and driving patterns.
The draft version of MOBILES was released on February 14, 1984. The
purpose of this draft version was to seek public opinions and
suggestions on the various changes and updates the MOBILES model had
made. Consequently, some revisions were made on the draft version.
The final version of MOBILES was released in June, 1984.
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The 1979 NPD survey data were fitted with an exponential function. The
first year mileage accumulation value of the 1979 NPD survey corresponded
to the average mileage accumulation rate of vehicles between the ages of
one and two. However, MOBILES needed the average mileage accumulation
rate of vehicles between the ages of zero and one. This value was
derived from the 1979 NPD survey data by redefining the data as ages two
through 21 and estimating year one from the fitted exponential function.
The LDGV annual average mileage accumulation rates used in MOBILE2,
MOBILES Draft and MOBILES final version are shown in Figure 5.
3.2 Light-Duty Diesel Vehicles
MOBILE2 used the LDGV rates for the LDDV mileage accumulation rates due
to insufficient LDDV data available at the time when MOBILE2 was
finalized.
The 1983 EEA report used the 1981 NPD survey data to estimate the LDDV
average annual mileage accumulations (Table 3-5 of the 1983 EEA report).
The results suggested that the average annual mileage accumulations of
LDDVs (for vehicles less than six years of age) would be slightly higher
than the LDGV rates during the same time frames. This might be due to
the fuel price effect on the driving patterns — as diesel fuel cost was
less, diesel vehicle owners tended to drive more than the gasoline
vehicle owners would.
The MOBILE3 Draft used the results from the 1983 EEA report as the data
base. The first four year rates were from the LDDV rates. The rates for
all other years were the LDGV rates. The combined data set was smoothed
by an exponential function. The predicted values were used for the
MOBILE3 Draft.
In the final version of MOBILE3, however, the LDGV annual average mileage
accumulations were also used for LDDVs. This was because the number of
diesels in the 1979 GMR-NPD survey data were not enough to develop a
realistic mileage accumulation distribution for diesel vehicles.
The LDDV mileage accumulation rates used for MOBILE2, MOBILES Draft and
the final version of MOBILES are plotted in Figure 6.
3.3 Light-Duty Gasoline and Diesel Trucks
The annual average mileage accumulation rates for LDTs from the MOBILE2
model were obtained from the 1980 EEA report (Ref. 5). Data from the
1983 EEA report were used as the data base for MOBILES. In this 1983 EEA
report, the annual mileage accumulations of LDTs were estimated from the
1977 TIUS (Truck Inventory and Use Survey) data. To adjust the estimated
1977 rates to represent the 1981 level, it was assumed that the shape of
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the 1977 travel distributions remain constant, but the absolute levels
were adjusted to reflect the 1977-1981 change in average annual miles per
single unit truck, as reported by the Federal Highway Administration.
This resulted in an ajustment factor of 1.134 for the light-duty truck
fleet. The adjusted rates were tabulated in Tables 3-12, 3-13 and 3-15
of the 1983 EEA report.
These adjusted mileage accumulation rates, however, were not used in
MOBILES. The adjustment factor of 1.134 was thought to be inappropriate
on two aspects: 1) The LDTs are expected to have somewhat higher annual
mileage accumulation rates than the LDVs because many of the LDTs are
used in commercial applications (such as in construction) or used as
campers. However, in comparison with the MOBILES LDGV rates, the
adjusted LDT rates seemed too high. For example, the first year mileage
of LDGTls was adjusted to be 19,724 miles, while the first year mileage
from LDGVs was 12,818 miles. 2) It may not be appropriate to adjust the
mileage accumulation rates "uniformly" for all twenty years. Thus, the
unadjusted rates were used as the data base for MOBILES.
The LDT mileage accumulation rates used for MOBILES are listed in
Appendix 4. The MOBILE2 rates are also listed for reference. Graphic
presentation of MOBILES versus MOBILE2 mileage accumulation rates for
LDTs are shown in Figures 7 through 9.
3.4 Heavy-Duty Gasoline Trucks
The annual average mileage accumulation rates for HDGVs from the MOBILE2
model were obtained from the 1980 EEA report. Data from the 1983 EEA
report were used as the data base for MOBILES. In this 1983 EEA report,
the annual mileage accumulations of HDGVs were also estimated from the
1977 TIUS data. Adjustment factors were derived in the same manner as
the light-duty trucks to adjust the 1977 rates to represent the 1981
levels. The adjustment factors were 1.132 for classes 2B through 5,
1.119 for class 6, and 0.957 for classes 7 and 8 heavy-duty trucks. The
adjusted rates can be found in Table 3-19 of the 1983 EEA report.
The unadjusted rates from the 1983 EEA report were used for MOBILES.
(The reasons for using the unadjusted rates are the same as the LDTs,
discussed in Section 3.3.) A separate EEA study (Ref. 6) on emissions
conversion factors and fuel economy for heavy-duty trucks indicated that
the historical and projected sales (Tables 3-7 and 3-8 of the EEA
conversion factors study) and use patterns (Table 2-2 of the EEA
conversion factors study) of the HDGVs over the years remain fairly
stable among the various weight classes. Therefore, it is appropriate to
use an overall average mileage distribution to represent the entire
heavy-duty gasoline fleet.
The HDGV mileage accumulation rates used for MOBILES are listed in
Appendix 5, with MOBILE2 rates listed also as reference. Graphic
presentation of MOBILES versus MOBILE2 rates are shown in Figure 10.
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3.5 Heavy-Duty Diesel Vehicles
The HDDV annual average mileage accumulation rates from the MOBILE2 model
were obtained from the 1980 EEA report. Data from the 1983 EEA report
were used as the data base for MOBILE3. In this 1983 EEA report, the
annual mileage accumulations of HDDVs were estimated from the 1977 TIUS
data, and adjusted to 1981 levels. The various classes of HDVs with
respect to their weights are shown in Table 4.
Table 4
Classification of HDVs
Weight Gross Vehicle
Class Weight (in Ibs)
2B 8,501 - 10,000
3-5 10,000 - 19,500
6 19,501 - 26,000
7 26,001 - 33,000
8 A&B more than 33,000
In the MOBILE2 model, the HDDV mileage accumulation rates were the
averages over all weight classes. The 1983 EEA report suggested that
three weight classes of HDDVs be considered separately, since the sales
trends and usage patterns vary among the light (classes 2B-5), medium
(class 6) and heavy (classes 7-8) diesel trucks. The adjusted mileage
accumulation rates of these three classes were tabulated in Tables 3-20
through 3-22 of the 1983 EEA report.
In the draft version of MOBILE3, the unadjusted mileage accumulation
rates of the light (classes 2B-5), medium, and heavy HDDVs from the 1983
EEA report were used. The annual mileage accumulations of these three
classes were then weighted by the estimated registrations in each class
by calendar year to derive a unique class-combined HDDV mileage
accumulation distribution for each calendar year.
For the final version of MOBILES, however, an additional class of
HDDVs—class 2B was created, or separated from the classes 2B-5 figures.
The sales of class 2B diesel trucks are projected to be increasing in the
future years, as evidenced by Table 3-8 of the EEA study on emissions
conversion factors and fuel economy for heavy-duty trucks (Ref. 6).
Also, class 2B trucks probably have mileage accumulation rates more like
class 2A trucks than classes 3-5 trucks. Therefore, it was necessary to
include a separate category for these class 2B diesel trucks in the
mileage calculations. Since the average annual mileage accumulations for
class 2B HDDVs were not readily available in the 1983 EEA report, the
LDGT2 mileage accumulation rates were used.
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The smoothed mileage accumulation rates of the four HDDV classes —2B,
light (classes 3-5), medium (class 6), and heavy (classes 7-8), are
listed in Appendix 6. The estimated total HDDV registrations by class
for years 1980 through 2000, obtained from another EEA report5 (Ref. 7)
are listed in Appendix 7. Graphic presentations of MOBILES versus
MOBILE2 rates are shown in Figure 11.
An example of how the overall HDDV mileage accumulations are derived from
all weight classes in a given calendar year is briefly presented here.
The estimated total 1982 HDDV registrations in millions were 0.049 for
class 2B, 0.009 for classes 3-5, 0.135 for class 6, and 1.599 for classes
7-8 heavy-duty trucks (obtained from Appendix 7). Therefore, the total
1982 HDDV registrations for all classes are 1.792 million (sum of all
classes, last column in Appendix 7). This yields registration fractions
of 2.7 percent for class 2B, 0.5 percent for classes 3-5, 7.5 percent for
class 6, and 89.3 percent for classes 7-8 HDDVs. The overall HDDV
mileage accumulations by age for the calendar year of 1982 were obtained,
as shown in Table 5, by weighting the annual average mileage accumulation
rates of the four weight classes (from Appendix 6) with their respective
registration fractions.
Appendix B of the EEA report entitled "October 1983 Output of the
Highway Fuel Consumption Model."
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Age
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
15
Table 5
1982 Calendar Year HDDV Registration Mix*
2B
(2.
18,
16,
15,
1*,
13,
,7%)
,352
,946
,648
,449
,342
3-5
(0.
45,
39,
34,
30,
26,
(Light)
5%)
544
671
558
092
213
6
(7
53
46
41
36
31
(Medium)
.5%)
,370
,901
,190
,206
,812
7-8
(89
82,
78,
68,
62,
56,
(Heavy)
.3%)
288
984
328
263
737
Weighted
Average
78,209
71,134
64,701
58,857
53,543
12,320
11,376
10,504
9,700
8,956
22,834
19,898
17,332
15,098
13,152
27,948
24,556
21,575
18,956
16,655
51,700
47,111
42,930
39,119
35,647
48,711
44,318
40,325
36,692
33,389
8,270
7,637
7,052
6,511
6,012
11,456
9,979
8,693
7,572
6,596
14,632
12,856
11,296
9,925
8,719
32,483
29,599
26,972
24,578
22,396
30,385
27,652
25,167
22,906
20,849
5,552
5,126
4,734
4,371
4,036
5,746
5,005
4,360
3,798
3,308
7,661
6,728
5,913
5,196
4,565
20,408
18,597
16,946
15,442
14,071
18,978
17,275
15,726
14,316
13,033
The registration fractions for the four HDDV classes are calculated
from the total registrations by class (Appendix 7) divided by the
overall HDDV registrations (last column of Appendix 7). Mileage
accumulation rates by age for the four HDDV classes are from Appendix
6.
-------
16
4.0 TOTAL VEHICLE COUNTS
The total numbers of vehicles of each vehicle type are used to estimate
the portion of the total mobile source vehicle-miles-traveled (VMT)
driven by each vehicle type. In MOBILE2/MOBILE3, the total vehicle
counts are given for six vehicle types: LDVs, LDTs, LDGT2s, HDGVs, HDDVs,
and MCs. Dieselization rate adjustment factors are used in the computer
program to split the LDV count into total LDGV and LDDV registration
counts, and also to split the LOT count into total LDGT1 and LDDT
registration counts.
Table 6 is a summary of the MOBILE2/MOBILE3 total vehicle counts by
vehicle type. The MOBILE2 counts were obtained from 1978 registrations
(Ref. 3), and the MOBILES counts were derived from estimates in
Department of Energy's Highway Fuel Consumption Model (Ref. 7).
Table 6
Total Vehicle Counts in Millions
Vehicle Type MOBILE3 MOBILE2
LDGV/LDDV 105,839 102,900
LDGT1/LDDT 18,072 12,900
LDGT2 11,506 5,700
HDGV 4,650 4,700
HDDV 1,640 1,000
MC 5,600 7,300
-------
17
References
1. Energy and Environmental Analysis, Inc., "Fleet Characterization
Data Final Report," prepared for the U.S. Environmental Protection
Agency, December 20, 1983.
2. "Compilation of Air Pollutant Emission Factors: Highway Mobile
Sources," EPA 460/3-81-005, March 1981.
3. Energy and Environmental Analysis, Inc., "National MOBILE2
Variable Estimates," prepared for the U.S. Environmental
Protection Agency, July 1980.
4. Correspondence from Mr. Barry Felrice, National Highway Traffic
Safety Administration, to Mr. Michael P. Walsh, Environmental
Protection Agency, March 31, 1980.
5. Energy and Environmental Analysis, Inc., "Techniques for
Estimating MOBILE2 Variables," prepared for the U.S. Environmental
Protection Agency, July 1980.
6. Energy and Environmental Analysis, Inc., "Historical and Projected
Emissions Conversion Factors and Fuel Economy for Heavy-Duty
Trucks 1962-2002," Prepared for Motor Vehicle Manufacturers
Association, December, 1983.
7. Energy and Environmental Analysis, Inc., "The Highway Fuel
Consumption Model: Tenth Quarterly Report," prepared for the U.S.
Department of Energy, October, 1983.
-------
18
Appendix 1
MOBILES July 1 Registration Distributions
Vehicle
Age
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20f
LDV*
0.080
0.101
0.095
0.089
0.083
0.077
0.071
0.065
0.059
0.053
0.047
0.041
0.035
0.029
0.023
0.017
0.011
0.008
0.006
0.008
LOT**
HDGV
HDDV
* The same distribution is used for LDGVs and LDDVs.
** The same distribution is used for LDGTls, LDGT2s and LDDTs.
*** Same as MOBILE2.
MC***
0.080
0.101
0.095
0.089
0.083
0.067
0.085
0.081
0.077
0.073
0.079
0.136
0.116
0.099
0.085
0.090
0.151
0.126
0.105
0.088
0.133
0.145
0.138
0.116
0.123
0.077
0.071
0.065
0.059
0.053
0.069
0.065
0.061
0.057
0.053
0.072
0.062
0.053
0.045
0.038
0.073
0.061
0.051
0.043
0.036
0.114
0.069
0.044
0.024
0.009
0.047
0.041
0.035
0.029
0.023
0.048
0.044
0.040
0.036
0.032
0.033
0.028
0.024
0.020
0.018
0.030
0.025
0.021
0.017
0.014
0.085
0.0
0.0
0.0
0.0
0.017
0.011
0.008
0.006
0.008
0.028
0.024
0.020
0.016
0.024
0.015
0.013
0.011
0.009
0.045
0.012
0.010
0.008
0.007
0.031
0.0
0.0
0.0
0.0
0.0
-------
19
Appendix 2
MOBILES Gasoline/Diesel Sales Fractions of LDVs and LDTs
MODEL
YEAR
Pre-1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995+
LDGV
1.000
0.997
0.997
0.996
0.991
0.972
0.966
0.939
0.954
0.947
0.940
0.934
0.927
0.920
0.910
0.900
0.887
0.887
0.886
0.886
0.885
0.885
LDGV
1.000
0.997
0.997
0.996
0.991
0.972
0.966
0.939
0.954
0.947
0.940
0.934
0.927
0.920
0.910
0.900
0.887
0.887
0.886
0.886
0.885
LDDV
0.000
0.003
0.003
0.004
0.009
0.028
0.034
0.061
0.046
0.053
0.060
0.066
0.073
0.080
0.090
0.100
0.113
0.113
0.114
0.114
0.115
LDGT (1&2)
1.000
0.998
0.997
0.995
0.991
0.972
0.966
0.940
0.920
0.900
0.870
0.840
0.820
0.790
0.760
0.730
0.706
0.697
0.688
0.679
0.670
LDDT
0.000
0.002
0.003
0.005
0.009
0.028
0.034
0.060
0.080
0.100
0.130
0.160
0.180
0.210
0.240
0.270
0.294
0.303
0.312
0.321
0.330
0.115
0.661
0.339
Source: Draft version of "Diesel Particulate Study," Table 2-6,
Standards Development and Support Branch, Emission Control Technology
Division, Office of Air and Radiation, U.S. Environmental Protection
Agency, 1984.
-------
20
Appendix 3
Annual Average Mileage Accumulation Rates for LDVs
MOBILES
Vehicle
Age
1 .
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20+
LDGV
Final
12,818
12,102
11,427
10,789
10,187
9,619
9,082
8,575
8,096
7,645
7,218
6,815
6,435
6,076
5,737
5,416
5,114
4,829
4,559
4,305
Draft
13,925
13,125
12,375
11,661
10,992
10,361
9,766
9,205
8,677
8,179
7,716
7,274
6,857
6,464
6,094
5,745
5,415
5,105
4,813
4,537
LDDV
Final
12,818
12,102
11,427
10,789
10,187
9,619
9,082
8,575
8,096
7,645
7,218
6,815
6,435
6,076
5,737
5,416
5,114
4,829
4,559
4,305
Draft
15,332
14,349
13,428
12,567
11,761
11,007
10,301
9,640
9,022
8,443
7,902
7,395
6,921
6,477
6,062
5,673
5,309
4,969
4,650
4,352
MOBILE2*
14,400
13,900
13,400
12,800
12,300
11,800
11,200
10,700
10,200
9,600
9,100
8,600
8,000
7,500
7,000
6,400
5,900
5,400
4,900
4,300
* In MOBILE2, the same LDGV rates are also used for LDDVs.
-------
LDGT1
17,394
16,132
14,961
13,876
12,869
LDGT2
18,352
16,946
15,648
14,449
13,342
LDDT
17,552
16,262
15,068
13,961
12,936
LDGT1
15,600
14,000
12,500
11,200
10,100
LDGT2
15,800
14,200
12,600
11,400
10,300
LDDT
15,700
15,100
14,600
14,000
13,000
21
Appendix 4
Annual Average Mileage Accumulation Rates for LOTS
Vehicle MOBILES MOBILE2
Age
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
204-
11,935
11,069
10,266
9,521
8,830
12,320
11,376
10,504
9,700
8,956
11,986
11,105
10,290
9,534
8,833
9,400
8,600
8,000
7,500
7,700
9,500
8,700
8,100
7,600
7,100
12,100
11,000
9,700
9,300
7,400
8,189
7,595
7,044
6,533
6,059
8,270
7,637
7,052
6,511
6,012
8,185
7,583
7,026
6,510
6,032
6,600
6,200
5,900
5,500
5,200
6,600
6,300
6,000
5,500
5,200
6,800
6,100
5,500
5,000
4,600
5,619
5,211
4,833
4,483
4,157
5,552
5,126
4,734
4,371
4,036
5,589
5,179
4,798
, 4,446
4,119
5,000
4,700
4,400
4,400
4,400
5,100
4,700
4,400
4,400
4,400
4,200
3,800
3,100
3,100
3,100
-------
Vehicle
Age
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20f
22
Appendix 5
Annual Average Mileage Accumulation Rates
MOBILES
19,967
18,077
16,365
14,815
13,413
12,143
10,993
9,952
9,010
8,156
7,384
6,685
6,052
5,479
4,960
4,490
4,065
3,680
3,332
3,016
for HDGVS
MOBILE2
21,000
18,900
17,200
15,500
14,100
12,600
11,300
10,300
9,400
8,600
8,000
7,300
6,700
6,300
5,900
5,500
5,200
5,000
5,000
5,000
-------
23
Appendix 6
Annual Average Mileage Accumulation Rates for HDDVS
MOBILE2
Vehicle : MOBILES (All Weight
Age 2B_ 3-5 (Light) 6 (Medium) 7-8 (Heavy) Classes)
1 18,352 45,544 53,370 82,288 70,400
2 16,946 39,671 46,901 74,984 66,900
3 15,648 34,558 41,190 68,328 60,600
4 14,449 30,092 36,206 62,263 54,200
5 13,342 26,213 31,812 56,737 47,900
6 12,320 22,834 27,948 51,700 43,700
7 11,376 19,898 24,556 47,111 39,400
8 10,504 17,332 21,575 42,930 36,600
9 9,700 15,098 18,956 39,119 34,500
10 8,956 13,152 16,655 35,647 33,100
2B
18,352
16,946
15,648
14,449
13,342
12,320
11,376
10,504
9,700
8,956
8,270
7,637
7,052
6,511
6,012
5,552
5,126
4,734
4,371
4,036
3-5 (Light)
45,544
39,671
34,558
30,092
26,213
22,834
19,898
17,332
15,098
13,152
11,456
9,979
8,693
7,572
6,596
5,746
5,005
4,360
3,798
3,308
6 (Medium)
53,370
46,901
41,190
36,206
31,812
27,948
24,556
21,575
18,956
16,655
14,632
12,856
11,296
9,925
8,719
7,661
6,728
5,913
5,196
4,565
7-8 (Heavy)
82,288
74,984
68,328
62,263
56,737
51,700
47,111
42,930
39,119
35,647
32,483
29,599
26,972
24,578
22,396
20,408
18,597
16,946
15,442
14,071
11 8,270 11,456 14,632 32,483 32,400
12 7,637 9,979 12,856 29,599 31,700
13 7,052 8,693 11,296 26,972 31,000
14 6,511 7,572 9,925 24,578 29,600
15 6,012 6,596 8,719 22,396 27,500
16 5,552 5,746 7,661 20,408 24,600
17 5,126 5,005 6,728 18,597 20,400
18 4,734 4,360 5,913 16,946 17,600
19 4,371 3,798 5,196 15,442 17,600
204- 4,036 3,308 4,565 14,071 17,600
-------
24
Appendix 7
Total HDDV Registrations by Class
for 1980 through 2000
Calendar
Year
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
Total Registrations (in Millions)
Class 2B
0.000
0.000
0.049
0.104
0.185
0.274
0.370
0.475
0.588
0.707
0.831
0.960
1.092
1.225
1.354
1.480
1.600
1.712
1.816
1.912
1.999
3-5 (Light)
0.006
0.006
0.009
0.013
0.022
0.037
0.053
0.071
0.089
0.106
0.122
0.137
0.151
0.165
0.178
0.190
0.202
0.212
0.222
0.230
0.238
6 (Medium)
0.112
0.124
0.135
0.141
0.153
0.166
0.177
0.185
0.193
0.201
0.208
0.215
0.222
0.229
0.237
0.245
0.253
0.261
0.269
0.276
0.283
7-8 (Heavy)
1.521
1.581
1.599
1.592
1.641
1.719
1.816
1.927
2.041
2.151
2.258
2.362
2.471
2.581
2.693
2.807
2.914
3.015
3.108
3.194
3.273
Overall
1.639
1.711
1.792
1.850
2.001
2.196
2.416
2.658
2.911
3.165
3.419
3.674
3.936
4.200
4.462
4.722
4.969
5.200
5.415
5.612
5.793
Source: EEA, prepared for the U.S. Department of Energy, "The Highway Fuel
Consumption Model, 10th Quarterly Report," October, 1983.
-------
Figure 1
LDV Registration Distributions
0.12-1
-------
0)
CD
cd
0.10-
0.08-
^^w
O
'S
3 0.06 H
CD
0)
FT* 0.04 H
O 0.02-
-------
Figure 3
HDGV Registration Distributions
0.20-,
0)
0)
O
• •—I
Cl
h—I
•s
0)
CD
0)
O
(H
0)
PL,
0.15-
0.10-
0.05-
0.00
1 1 1 1 1 1 1 1 1 1 1 \ T~
8 9 10 11 12 13 14 15 16 17 18 19 20
234567
Vehicle Age (Years)
Legend
A MOBILE2
X 1981 FOLK
D MOBILE3
-------
0.20-.
Figure 4
HDDV Registration Distributions
0)
$ 0.15-^
JU
(D
O
(H
0)
a*
o.ioH
0.05 H
0.00 -—i—i—i—i—i—r
123456
i—i—i—i—i—i—i—i i i i i
7 8 9 10 11 12 13 14 15 16 17 18 19 20
Vehicle Age (Years)
Legend
A MOBILE2
X 1981 POLK
0 MOBILE3
-------
Figure 5 : LDGV
Vehicle Miles Traveled Distributions
16000-.
14000-
0)
i—H
8J 12000
(3
ft
w
JS 10000
• I—I
s
o
8000-
6000-
4000
I T I I I I I I I I I I I I I I I I I I
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Legend
A MOBILE2
X M3 DRAFT
D MOBILE3
Vehicle Age (Years)
-------
•~^»
£
W
16000-1
14000-
JO)
£ 12000-
10000-
(D
r—i
• 8000H
6000-
4000
Figure 6 : LDDV
Vehicle Miles Traveled Distributions
I I
I I I I I I I I I I I I I T
Legend
A MOBILE2
X M3 DRAFT
D MOBILE3
1 23 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Vehicle Age (Years)
-------
Figure 7 : LDGT1
Vehicle Miles Traveled Distributions
80000-1
CD
•—I
I
CO
-------
Figure 8 : LDGT2
Vehicle Miles Traveled Distributions
20000 -.
-------
Figure 9 : LDDT
Vehicle Miles Traveled Distributions
20000-1
CD
i—i
0)
Ed
w
CD
•—i
•rH
a
CD
i—i
O
15000-1
10000-1
5000 H
Legend
A MOBILE2
X MOBILE3
12345
6789 10 11 12 13 14 15 16 17 18 19 20
Vehicle Age (Years)
-------
Figure 10 : HDGV
Vehicle Miles Traveled Distributions
25000-1
20000-
I
CO
CD
15000-
0) 10000
I—I
o
5000-
Legend
A MOBILE2
X MOBILE3
i i i i r r
I T I I I I
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Vehicle Age (Years)
-------
-o
------- |