Vehicle miles traveled can be converted to hours of travel using average speeds.  The average speed estimates were taken directly from the AvgSpeedDistribution table of the MOVES default database. The default average speed distributions do not vary by county or source type, but do vary by road type, day type (weekday and weekend day) and hour of the day.  The 2011 NEI VMT was aggregated into the four MOVES road types in each county.  The VMT by road type in each county was then allocated to day type and hour of the day using the day type and hour distributions from the MOVES default database tables, DayMVTFraction and HourVMTFraction.

Using the nominal speeds for each average speed bin in the AvgSpeedDistribution table for each hour of each day type and the corresponding VMT, the hours of vehicle operation (SHO) can be calculated for each hour of the day on each road type for each day type in each county.  The average speed distribution is in units of time, so the distribution must be converted to units of distance to be applied to the VMT values.  For this step, we  multiplied each value of each distribution (in terms of time) by the corresponding nominal average speed value for that average speed bin to calculate distance (hours * miles/hour).  Then we divided each distance value in the distribution by the sum of all distance values in that distribution to calculate the average speed distribution in terms of distance.

Finally, we multiplied the total VMT corresponding to each average speed distance distribution (by road type, by day type, by hour of the day) by each of the values in the distribution to calculate the VMT corresponding to each average speed bin.  We then then calculated operating hours by dividing the VMT in each average speed bin by the corresponding nominal average speed value.

                  SHO = VMT (miles) / Speed (miles per hour)
Equation 29

Once the hours of operation have been calculated, the hours in each county were summed by road type.  The allocation factor for each county was calculated by dividing the county hours for each road type by the national total hours of operation for each road type.

SHOAllocFactor = County SHO / National SHO
Equation 30

The county allocation values for each roadway type sum to one (1.0) for the nation.  The same SHOAllocFactor set is the default for all calendar years at the National scale.  County- and Project-level calculations do not use the default SHOAllocFactor allocations at all. Instead, County and Project scales require that the user input all local activity.

 Engine Start Allocations to Zones
The allocation of the domain-wide count of engine starts to zones is stored in the StartAllocFactor in the Zone table. In the default database for MOVES2014, the domain is the nation and the zones are counties. There is no national source for data on the number of trip starts by county, so for MOVES2014, we have used VMT to determine this allocation.  VMT for each county was taken from the most recent National Emission Inventory analysis for calendar year 2011.[66]

VMT estimates for each county in each state and the allocation is calculated using the following formula, where i represents each individual county and I is the set of all US counties.

CountyAllocationi= CountyVMTiiϵICountyVMTi
Equation 31

The county allocation values sum to one (1.0) for the nation.  The same StartAllocFactor set is the default for all calendar years at the National scale.  County- and Project-level calculations do not use the default StartAllocFactor allocations at all. Instead, County and Project scales require that the user input all local activity.

 Parking Hours Allocation to Zones
The allocation of the domain-wide hours of parking (engine off) to zones is stored in the SHPAllocFactor in the Zone table. In the default database for MOVES2014, the domain is the nation and the zones are the counties. There is no national source for hours of parking by county, so for MOVES2014, we have used the same VMT-based allocation as used for the allocation of starts in the StartAllocFactor (see above).

The county allocation values for parking hours sum to one (1.0) for the nation.  The same SHPAllocFactor set is the default for all calendar years at the National scale.  County- and Project-level calculations do not use the default SHPAllocFactor allocations at all. Instead, County and Project scales require that the user input all local activity.

In MOVES2014, hotelling hours (including extended idling and auxiliary power unit usage) are calculated from long haul combination truck VMT in each location and does have its own allocation factors.

Vehicle Mass and Road Load Coefficients
The MOVES model calculates emissions using a weighted average of emisson rates by operating mode. This level of detail is required for microscale modeling, which in MOVES is called project level analysis. For running exhaust emissions, the operating modes are defined by either Vehicle Specific Power (VSP) or Scaled Tractive Power (STP). Both VSP and STP are calculated based on a vehicle's speed and acceleration but differ in how they are scaled (or normalized). VSP is used for light-duty vehicles (source types 11-32) and STP is used for heavy-duty vehicles (source types 41-62).

The SourceUseTypePhysics table describes the vehicle characteristics needed for the VSP and STP calculations, including average vehicle mass, a fixed mass factor, and three road load coefficients for each source type averaged over all ages. MOVES uses these to calculate VSP and STP for each source type according the equations:

                  VSP=AM∙v+BM∙v2+CM∙v3+a+g∙sinθ∙v
                                                                    Equation 32

                   STP=Av+Bv2+Cv3+M∙v∙at+g∙sinθfscale
                                                                    Equation 33
where A, B, and C are the road load coefficients in units of kW-sm, kW-s2m2, and kW-s3m3  respectively.  A is associated with tire rolling resistence, B with mechanical rotating friction as well as higher order rolling resistance losses, and C with aerodynamic drag. M is the source mass for the source type in metric tons, g is the acceleration due to gravity 9.8 ms2, v is the instantaneous vehicle speed in ms, a is the instantaneous vehicle acceleration in ms2, sinθ is the (fractional) road grade, and fscale is a scaling factor.

When mapping actual emissions data to VSP bins with Equation 20, the vehicle's measured weight is used as the source mass factor. In contrast, when calculating average VSP distributions for an entire source type with MOVES, the average source type mass is used instead. STP is calculated with Equation 21, which is very similar to the VSP equation except the denominators are different. In the case of VSP, the power is normalized by the mass of the vehicle (fscale=M). For heavy-duty vehicles using STP, fscale depends on their regulatory class and is used to bring the numerical range of tractive power into the same numerical range as the VSP values when assigning operating modes. Class 40 trucks use fscale= 2.06, which is equal to the mass of source type 32 in metric tons. This is because operating modes for passenger trucks and light-commercial trucks are assigned operating modes using VSP, and using a fixed mass factor of 2.06 essentially calculates VSP-based emission rates. Running operating modes for all the heavy-duty source types (buses, single unit, and combination trucks) are assigned using STP with fscale=17.1, which is roughly equivalent to the average running weight in metric tons of all heavy-duty vehicles. Additional discussion regarding VSP and STP are provided in the MOVES light-duty[3] and heavy-duty[4] emission rate reports, respectively.

In both cases, operating mode distributions are derived from combining second-by-second speed and acceleration data from a specific drive schedule with the proper coefficients for a specific source type. More information about drive schedules can be found in Section 10.1.  The following sections detail the derivation of values used in Equation 20 and Equation 21.
 Source Mass and Fixed Mass Factor
The two mass factors stored in the SourceUseTypePhysics table are the source mass and fixed mass factor. The source mass represents the average weight of a given source type, which includes the weight of the vehicle, occupants, fuel, and payload (Min the equations above), and the fixed mass factor represents the STP scaling factor (fscale in the equations above).

While the source masses for light-duty were unchanged from MOVES2010b, all of the heavy-duty source masses were updated with newer data. Please see Section 21. (Appendix E: MOVES2010b Source Masses) for a discussion of the MOVES2010b source masses. The heavy-duty source masses for 2014+ model year vehicles heavy-duty vehicles were first updated to account for the 2014 Medium and Heavy-Duty Greenhouse Gase Rule as discussed in Section 14.2. Then the heavy-duty source masses were updated with 2011 Weigh-in-Motion (WIM) data made available through FHWA's Vehicle Travel Information System (VTRIS). These data are available from FHWA by state, road type, and HPMS truck type (single unit or combination). The average national mass by truck type was calculated by weighting the masses with VMT by state and road type using FHWA's Highway Statistics VM-2 table. These average values then needed to be allocated from the HPMS truck classification to source types. This allocation was performed using the percent difference between the average WIM HPMS mass and the average MOVES2010b HPMS mass. The MOVES2010b average masses were calculated by weighting the source type masses with the updated 2011 VMT. The percentage difference between the average single unit truck mass in MOVES2010b and the WIM data was then applied to the source masses of Single Unit Short-haul Trucks, Single Unit Long-haul Trucks, Refuse Trucks, and Motor Homes. Likewise, the percentage difference between the average combination truck mass in MOVES2010b and the WIM data was applied to the source masses of Combination Short-haul Trucks and Combination Long-haul Trucks, including the 2014+ model year groups. These differences are shown in Table 14-1, and the resulting source type masses are presented in Table 14-4.

            Table 14-1 Weigh-in-Motion (WIM) Masses Weighted by VMT
                                 HPMS Category
                             Average Weight (lbs)
                           % Change from MOVES2010b
                              Single Unit Trucks
                                    20,107
                                     11.7%
                              Combination Trucks
                                    52,907
                                    -21.7%

 Road Load Coefficients
The information available on road load coefficients varied by regulatory class. Motorcycle road load coefficients were parameterized, in accordance with standard practice, using the following emperical equations[,]:

                                  A=0.088∙M
                                  Equation 34

                                      B=0
                                  Equation 35

                            C=0.00026+0.000194∙M
                                  Equation 36
For light-duty vehicles, the road load coefficients were calculated according to the following empirical equations:

                    A=0.745750∙0.447∙0.35∙TRLHP@50mph
                                  Equation 37

                   B=0.745750∙0.4472∙0.10∙TRLHP@50mph
                                  Equation 38

                   C=0.745750∙0.4473∙0.55∙TRLHP@50mph
                                  Equation 39
In each of the above equations, the first factor is the appropriate unit conversion to allow A, B, and C to be used in Equation 20 and Equation 21, the second factor is the power distribution into each of the three load categories, and the third is the tractive road load horsepower rating (TRLHP). Average values for A, B, and C for source types 21, 31, and 32 were derived from applying TRLHP values recorded in the Mobile Source Observation Database (MSOD) to Equation 25-Equation 27. While we expect light-duty road load coefficients to improve over time due to the Light-Duty Greenhouse Gas Rule, the impact of these changes have been directly incorporated into the emission and energy rates. Therefore, these coefficients remain constant over time.

For the heavier vehicles, no road load parameters were available in the MSOD. For these source types, relationships of road load coefficent to vehicle mass came from a study done by V.A. Petrushov, as shown in Table 14-2. These relationships are grouped by regulatory class; source type values were determined by weighting the combination of MOVES2010b weight categories that comprise the individual source types. The final SourceMass, FixedMassFactor and road load coefficients for all source types are listed in Table 14-4.

Table 14-2 Road Load Coefficients for Heavy-Duty Trucks, Buses, and Motor Homes for 1960-2013 Model Year Vehicles
                                  Coefficient
                               8500 to 14000 lbs
                          (3.855 to 6.350 metric ton)
                              14000 to 33000 lbs
                         (6.350 to 14.968 metric ton)
                                 >33000 lbs
                            (>14.968 metric ton)
                             Buses and Motor Homes
                                    AkW-sm
                                  0.0996∙M
                                  0.0875∙M
                                  0.0661∙M
                                  0.0643∙M
                                   BkW-s2m2
                                       0
                                       0
                                       0
                                       0
                                   CkW-s3m3
                                   0.00289+
                                5.22x10-5∙M
                                   0.00193+
                                5.90x10-5∙M
0.00289+
4.21x10-5∙M
                                    0.0032+
                                5.06x10-5∙M

In MOVES2014, the vehicle mass and road load coefficient were updated for 2014 and later model year heavy-duty vehicles to account for the 2014 Medium and Heavy-Duty Greenhouse Gase Rule. Table 14-3 contains the combination long-haul tractor and vocational vehicle tire rolling resistance, coefficient of drag, and weight reductions expected from the technologies which could be used to meet the standards.  The value in the table reflects a 400 pound mass reduction.  As discussed in the rulemaking, EPA used a sales mix of 10 percent Class 7 low roof, 10 percent Class 7 high roof, 45 percent Class 8 low roof, and 35 percent Class 8 high roof based on feedback from the manufacturers.

The values in the table reflect a modeling assumption that 8 percent of all tractors (19.7 percent of short-haul tractors) would be considered vocational tractors and therefore will only be required to meet the vocational vehicle standards and not show any aerodynamic or weight improvement. The weight reduction applied to short-haul tractors is 321 pounds which is calculated from the 400 pound weight reduction assumed for non-vocational tractors, reduced by 19.7 percent.  The tire rolling resistance reduction is assumed to be 5 percent based on the data derived in the tire testing program conducted by EPA. Comparatively tire rolling resistance is reduced by 9.6 percent for long-haul tractors and 7 percent for short-haul tractors while aerodynamic drag is reduced 12.1 percent for long-haul tractors and 5.9 percent for short-haul tractors in model year 2014 and later. For further details on these assumptions about reductions in source mass and road load coefficients, please see the rulemaking documents. Discussion of incorporating the rule's energy reductions from engine technology improvements into MOVES can be found in the MOVES2014 Heavy-Duty Emission Rate Report.[4]

Table 14-3 Estimated Reductions in Rolling Resistance and Aerodynamic Drag Coefficients from Reference Case for Alternative 3 (Model Years 2014 and Later)
                                  TRUCK TYPE
        REDUCTION IN TIRE ROLLING RESISTANCE COEFFICIENT FROM BASELINE
            REDUCTION IN AERODYNAMIC DRAG COEFFICIENT FROM BASELINE
                            WEIGHT REDUCTION (LBS)
Combination long-haul
                                     9.6%
                                     12.1%
                                      400
Combination short-haul
                                     7.0%
                                     5.9%
                                      321
Vocational vehicles (Single-unit trucks, refuse trucks, motor homes, buses, and light commercial trucks)
                                     5.0%
                                      0%
                                       0

      These changes are represented in MOVES2014 through new aerodynamic coefficients and weights, and they primarily affect short- and long-haul combination truck source types beginning in MY 2014. The average vehicle mass and road load coefficients are updated by source type through the beginModelYearID and endModelYearID fields in the SourceUseTypePhysics table.

                     Table 14-4 SourceUseTypePhysics Table
                                 sourceTypeID
                               Begin Model Year
                                      End
                                  Model Year
                                    Rolling
                                    Term A
                                   (kW-s/m)
                                   Rotating
                                    Term B
                                (kW-s[2]/m[2])
                                     Drag
                                    Term C
                                  (kW-s3/m3)
                                  Source Mass
                                 (metric tons)
                        Fixed Mass Factor (metric tons)
                                      11
                                     1960
                                     2050
                                    0.0251
                                       0
                                    0.0003
                                    0.2850
                                    0.2850
                                      21
                                     1960
                                     2050
                                    0.1565
                                    0.0020
                                    0.0005
                                    1.4788
                                    1.4788
                                      31
                                     1960
                                     2050
                                    0.2211
                                    0.0028
                                    0.0007
                                    1.8669
                                    1.8669
                                      32
                                     1960
                                     2050
                                    0.2350
                                    0.0030
                                    0.0007
                                    2.0598
                                    2.0598
                                      41
                                     1960
                                     2013
                                    1.2952
                                       0
                                    0.0037
                                    19.5937
                                     17.1
                                      41
                                     2014
                                     2050
                                    1.2304
                                       0
                                    0.0037
                                    19.5937
                                     17.1
                                      42
                                     1960
                                     2013
                                    1.0944
                                       0
                                    0.0036
                                    16.5560
                                     17.1
                                      42
                                     2014
                                     2050
                                    1.0397
                                       0
                                    0.0036
                                    16.5560
                                     17.1
                                      43
                                     1960
                                     2013
                                    0.7467
                                       0
                                    0.0022
                                    9.0699
                                     17.1
                                      43
                                     2014
                                     2050
                                    0.7094
                                       0
                                    0.0022
                                    9.0699
                                     17.1
                                      51
                                     1960
                                     2013
                                    1.5835
                                       0
                                    0.0036
                                    23.1135
                                     17.1
                                      51
                                     2014
                                     2050
                                    1.5043
                                       0
                                    0.0036
                                    23.1135
                                     17.1
                                      52
                                     1960
                                     2013
                                    0.6279
                                       0
                                    0.0016
                                    8.5390
                                     17.1
                                      52
                                     2014
                                     2050
                                    0.5965
                                       0
                                    0.0016
                                    8.5390
                                     17.1
                                      53
                                     1960
                                     2013
                                    0.5573
                                       0
                                    0.0015
                                    6.9845
                                     17.1
                                      53
                                     2014
                                     2050
                                    0.5294
                                       0
                                    0.0015
                                    6.9845
                                     17.1
                                      54
                                     1960
                                     2013
                                    0.6899
                                       0
                                    0.0021
                                    7.5257
                                     17.1
                                      54
                                     2014
                                     2050
                                    0.6554
                                       0
                                    0.0021
                                    7.5257
                                     17.1
                                      61
                                     1960
                                     2013
                                    1.5382
                                       0
                                    0.0040
                                    22.9745
                                     17.1
                                      61
                                     2014
                                     2050
                                    1.4305
                                       0
                                    0.0038
                                    22.8289
                                     17.1
                                      62
                                     1960
                                     2013
                                    1.6304
                                       0
                                    0.0042
                                    24.6010
                                     17.1
                                      62
                                     2014
                                     2050
                                    1.4739
                                       0
                                    0.0037
                                    24.4196
                                     17.1

Air Conditioning Activity Inputs
This report describes three inputs used in determining the impact of air conditioning on emissions. The ACPenetrationFraction is the fraction of vehicles equipped with air conditioning. FunctioningACFraction describes the fraction of these vehicles in which the air conditioning system is working correctly. The ACActivityTerms relate air conditioning use to local heat and humidity. More information on air conditioning effects is provided in the MOVES technical report on adjustment factors.

ACPenetrationFraction
The ACPenetrationFraction is a field in the SourceTypeModelYear table. Default values, by source type and model year were taken from MOBILE6. Market penetration data by model year were gathered from Ward's Automotive Handbook for light-duty vehicles and light-duty trucks for model years 1972 through the 1995 for cars and 1975-1995 for light trucks. Rates in the first few years of available data are quite variable, so values for early model years were estimated by applying the 1972 and 1975 rates for cars and trucks, respectively. Projections beyond 1995 were developed by calculating the average yearly rate of increase in the last five years of data and applying this rate until a predetermined cap was reached. A cap of 98 percent was placed on cars and 95 percent on trucks under the assumption that there will always be vehicles sold without air conditioning, more likely trucks than cars. No data was available on heavy-duty trucks. While VIUS asks if trucks are equipped with A/C, "no response" was coded the same as "no," making the data unusable for this purpose. For MOVES, the light-duty vehicle rates were applied to passenger cars, and the light-duty truck rates were applied to all other source types (except motorcycles, for which A/C penetration is assumed to be zero).

               Table 15-1 AC Penetration Fractions in MOVES2014

                                  Motorcycles
                                Passenger Cars
                             All Trucks and Buses
                               1972-and-earlier
                                       0
                                     0.592
                                     0.287
                                     1973
                                       0
                                     0.726
                                     0.287
                                     1974
                                       0
                                     0.616
                                     0.287
                                     1975
                                       0
                                     0.631
                                     0.287
                                     1976
                                       0
                                     0.671
                                     0.311
                                     1977
                                       0
                                     0.720
                                     0.351
                                     1978
                                       0
                                     0.719
                                     0.385
                                     1979
                                       0
                                     0.694
                                     0.366
                                     1980
                                       0
                                     0.624
                                     0.348
                                     1981
                                       0
                                     0.667
                                     0.390
                                     1982
                                       0
                                     0.699
                                     0.449
                                     1983
                                       0
                                     0.737
                                     0.464
                                     1984
                                       0
                                     0.776
                                     0.521
                                     1985
                                       0
                                     0.796
                                     0.532
                                     1986
                                       0
                                     0.800
                                     0.544
                                     1987
                                       0
                                     0.755
                                     0.588
                                     1988
                                       0
                                     0.793
                                     0.640
                                     1989
                                       0
                                     0.762
                                     0.719
                                     1990
                                       0
                                     0.862
                                     0.764
                                     1991
                                       0
                                     0.869
                                     0.771
                                     1992
                                       0
                                     0.882
                                     0.811
                                     1993
                                       0
                                     0.897
                                     0.837
                                     1994
                                       0
                                     0.922
                                     0.848
                                     1995
                                       0
                                     0.934
                                     0.882
                                     1996
                                       0
                                     0.948
                                     0.906
                                     1997
                                       0
                                     0.963
                                     0.929
                                     1998
                                       0
                                     0.977
                                     0.950
                                     1999+
                                       0
                                     0.980
                                     0.950

FunctioningACFraction
The FunctioningACFraction field in the SourceTypeAge table indicates the fraction of the air-conditioning equipped fleet with fully functional A/C systems, by source type and vehicle age. A value of 1 means all systems are functional. This is used in the calculation of total energy to account for vehicles without functioning A/C systems. Default estimates were developed for all source types using the "unrepaired malfunction" rates used for 1992-and-later model years in MOBILE6. The MOBILE6 rates were based on the average rate of A/C system failure by age reported in a consumer study and assumptions about repair frequency during and after the warranty period. The MOBILE6 rates were applied to all source types except motorcycles, which were assigned a value of zero for all years.

 Table 15-2 FunctioningACFraction by Age (All Source Types except Motorcycles)
                                     ageID
                             functioningACFraction
                                       0
                                       1
                                       1
                                       1
                                       2
                                       1
                                       3
                                       1
                                       4
                                     0.99
                                       5
                                     0.99
                                       6
                                     0.99
                                       7
                                     0.99
                                       8
                                     0.98
                                       9
                                     0.98
                                      10
                                     0.98
                                      11
                                     0.98
                                      12
                                     0.98
                                      13
                                     0.96
                                      14
                                     0.96
                                      15
                                     0.96
                                      16
                                     0.96
                                      17
                                     0.96
                                      18
                                     0.95
                                      19
                                     0.95
                                      20
                                     0.95
                                      21
                                     0.95
                                      22
                                     0.95
                                      23
                                     0.95
                                      24
                                     0.95
                                      25
                                     0.95
                                      26
                                     0.95
                                      27
                                     0.95
                                      28
                                     0.95
                                      29
                                     0.95
                                      30
                                     0.95

ACActivityTerms
In the MonthGroupHour table, ACActivityTerms A, B, and C are coefficients for a quadratic equation that calculates air conditioning activity demand as a function of the heat index. These terms are applied in the calculation of the A/C adjustment in the energy consumption calculator. The methodology and the terms themselves were originally derived for MOBILE6 and are documented in the report, Air Conditioning Activity Effects in MOBILE6.74 They are based on analysis of air conditioning usage data collected in Phoenix, Arizona, in 1994.

In MOVES, ACActivityTerms are allowed to vary by monthGroup and Hour, in order to provide the possibility of different A/C activity demand functions at a given heat index by season and time of day (this accounts for differences in solar loading observed in the original data). However, for MOVES2014, the default data uses one set of coefficients for all MonthGroups and Hours. These default coefficients represent an average A/C activity demand function over the course of a full day. The coefficients are listed in Table 15-3.

               Table 15-3 Air Conditioning Activity Coefficients
                                       A
                                       B
                                       C
                                   -3.63154
                                   0.072465
                                   -0.000276

The A/C activity demand function that results from these coefficients is shown in Figure 15-1. A value of 1 means the A/C compressor is engaged 100 percent of the time; a value of 0 means no A/C compressor engagement.

   Figure 15-1 Air Conditioning Activity Demand as a Function of Heat Index
0
0
.
1
0
.
2
0
.
3
0
.
4
0
.
5
0
.
6
0
.
7
0
.
8
0
.
9
1
7
0
7
5
8
0
8
5
9
0
9
5
1
0
0
1
0
5
1
1
0
H
e
a
t

I
n
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e
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(
F
)
0
0
.
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0
.
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.
3
0
.
4
0
.
5
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.
6
0
.
7
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.
8
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.
9
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7
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7
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8
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9
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H
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a
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I
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(
F
)
Conclusion and Areas for Future Research
Properly characterizing emissions from vehicles requires a detailed understanding of the cars and trucks that make up the vehicle fleet, and their patterns of operation. The national default information in MOVES2014 provide a reliable basis for estimating national emissions. The most important of these inputs are well-established: base year VMT and population estimates come from long-term, systematic national measurements by US Department of Transportation. The emission characteristics for the most prevalent vehicle classes are well-known; base year age distributions are well-measured, and driving activity has been the subject of much study in recent years.

Still, the fleet and activity inputs do have significant limitations, and the uncertainties and variability in this data can contribute significant uncertainty in resulting emission estimates. Thus it is often appropriate to replace many of the MOVES fleet and activity defaults with local data as explained in EPA's Technical Guidance.

The fleet and activity defaults also are limited by the necessity of forecasting future emissions. EPA utilizes annual US Department of Energy forecasts of vehicle sales and activity, but the inputs for MOVES2014 were developed for a 2011 base year, and much of the source data is from 2011-and-earlier. This information needs to be updated periodically to assure that the model defaults reflect the latest available data and projections on the US fleet.

Updating the vehicle fleet data will be complicated by the fact that one of the primary data sources for this document, the Census Bureau's Vehicle Inventory and Use Survey, has been discontinued. EPA is currently working with DOT and other federal agencies to revive this survey.  Doing so becomes more and more important as the data gathered from the last survey (2002) ages.

A related complication is the cost of data. Collecting data on vehicle fleet and activity is expensive, especially when the data is intended to accurately represent the entire United States. Even when EPA does not generate data directly (for example, compilations of state vehicle registration data) obtaining the information needed for MOVES can be costly and, thus, dependent on large-scale budget choices.

In addition to these general limitations, there are also specific MOVES data elements that could be improved with additional research, including,

      * Real-world highway driving cycles and operating mode distributions,
      * Off-network behavior including vehicle starts and soaks,
      * Truck hotelling, particularly extended engine idling and APU use,
      * VSP/STP adjustments for speed, road grade, and loading,
      * Age effects such as mileage accumulation and scrappage,
      * Summaries of real-time GPS and on-board diagnostic device data streams,
      * Vehicle identification and sorting by size, sector, and vocation.
      * Activity weighting of source mass averages.
      * Air Conditioning system penetration and failure rates.
      * Vehicle type distinctions in temporal activity,
      * Heavy truck and bus daily trip activity patterns (particularly at night).

Future updates to vehicle population and activity defaults will need to continue focus on the most critical elements required for national fleet-wide estimates, namely gasoline light-duty cars and trucks, and diesel heavy-duty trucks. Information collection on motorcycles, refuse trucks, motor homes, diesel light-duty vehicles and gasoline heavy-duty vehicles will be a lower priority. In addition to updating the model defaults, we will need to consider whether the current MOVES design continues to meet our modeling needs. Simplifications to the model to remove categories, such as source types or road types, might make noticeable improvements in run time without affecting the validity of fleet-wide emission estimates.

At the same time, the fundamental MOVES assumption that vehicle activity varies by source type and not by fuel type or other source bin characteristic may be challenged by the growing market share of electric vehicles and other vehicles that may have distinct activity patterns. As we progress with MOVES, the development of vehicle population and activity inputs will continue to be an essential area of research.

Appendix A: Projected Source Type Populations by Year
Table 17-1: Source type populations (in thousands), as derived from HPMS populations in §5.2 and the age distribution algorithm in §<IP_ADDRESS>.
                                     Year
                                  Motorcycle
                                 Passenger Car
                                Passenger Truck
                               Light Comm. Truck
                                 Intercity Bus
                                  Transit Bus
                                  School Bus
                                 Refuse Truck
                            Single Unit Short-haul
                             Single Unit Long-haul
                                  Motor Home
                            Combination Short-haul
                             Combination Long-haul
                                                                           2012
                                                                           8571
                                                                         128033
                                                                          86859
                                                                          21393
                                                                             18
                                                                             69
                                                                            617
                                                                            185
                                                                           6194
                                                                            260
                                                                           1559
                                                                           1191
                                                                           1280
                                                                           2013
                                                                           8687
                                                                         129764
                                                                          87924
                                                                          21791
                                                                             19
                                                                             72
                                                                            643
                                                                            195
                                                                           6525
                                                                            274
                                                                           1643
                                                                           1234
                                                                           1332
                                                                           2014
                                                                           8706
                                                                         130054
                                                                          88014
                                                                          21960
                                                                             20
                                                                             74
                                                                            663
                                                                            203
                                                                           6777
                                                                            285
                                                                           1708
                                                                           1258
                                                                           1377
                                                                           2015
                                                                           8747
                                                                         130666
                                                                          88345
                                                                          22167
                                                                             21
                                                                             77
                                                                            691
                                                                            213
                                                                           7093
                                                                            299
                                                                           1788
                                                                           1306
                                                                           1439
                                                                           2016
                                                                           8844
                                                                         132117
                                                                          89259
                                                                          22492
                                                                             22
                                                                             80
                                                                            720
                                                                            223
                                                                           7392
                                                                            312
                                                                           1863
                                                                           1354
                                                                           1503
                                                                           2017
                                                                           8943
                                                                         133583
                                                                          90198
                                                                          22803
                                                                             22
                                                                             82
                                                                            740
                                                                            230
                                                                           7589
                                                                            322
                                                                           1915
                                                                           1380
                                                                           1555
                                                                           2018
                                                                           9018
                                                                         134715
                                                                          90934
                                                                          23043
                                                                             23
                                                                             84
                                                                            753
                                                                            235
                                                                           7709
                                                                            328
                                                                           1946
                                                                           1390
                                                                           1600
                                                                           2019
                                                                           9098
                                                                         135907
                                                                          91718
                                                                          23279
                                                                             23
                                                                             86
                                                                            766
                                                                            239
                                                                           7824
                                                                            333
                                                                           1977
                                                                           1400
                                                                           1645
                                                                           2020
                                                                           9178
                                                                         137105
                                                                          92513
                                                                          23508
                                                                             23
                                                                             87
                                                                            780
                                                                            243
                                                                           7953
                                                                            335
                                                                           2012
                                                                           1410
                                                                           1690
                                                                           2021
                                                                           9260
                                                                         138317
                                                                          93324
                                                                          23730
                                                                             24
                                                                             88
                                                                            794
                                                                            247
                                                                           8093
                                                                            340
                                                                           2053
                                                                           1422
                                                                           1737
                                                                           2022
                                                                           9337
                                                                         139471
                                                                          94098
                                                                          23939
                                                                             24
                                                                             90
                                                                            809
                                                                            252
                                                                           8242
                                                                            345
                                                                           2095
                                                                           1437
                                                                           1783
                                                                           2023
                                                                           9416
                                                                         140653
                                                                          94892
                                                                          24150
                                                                             25
                                                                             92
                                                                            824
                                                                            256
                                                                           8385
                                                                            351
                                                                           2134
                                                                           1453
                                                                           1828
                                                                           2024
                                                                           9498
                                                                         141880
                                                                          95725
                                                                          24361
                                                                             25
                                                                             93
                                                                            838
                                                                            260
                                                                           8510
                                                                            352
                                                                           2168
                                                                           1466
                                                                           1872
                                                                           2025
                                                                           9585
                                                                         143179
                                                                          96598
                                                                          24591
                                                                             26
                                                                             95
                                                                            853
                                                                            264
                                                                           8638
                                                                            357
                                                                           2204
                                                                           1482
                                                                           1918
                                                                           2026
                                                                           9680
                                                                         144593
                                                                          97557
                                                                          24833
                                                                             26
                                                                             97
                                                                            867
                                                                            267
                                                                           8752
                                                                            362
                                                                           2239
                                                                           1495
                                                                           1964
                                                                           2027
                                                                           9781
                                                                         146100
                                                                          98575
                                                                          25092
                                                                             27
                                                                             98
                                                                            879
                                                                            269
                                                                           8846
                                                                            366
                                                                           2266
                                                                           1505
                                                                           2005
                                                                           2028
                                                                           9888
                                                                         147713
                                                                          99664
                                                                          25368
                                                                             27
                                                                             99
                                                                            889
                                                                            272
                                                                           8927
                                                                            371
                                                                           2288
                                                                           1514
                                                                           2040
                                                                           2029
                                                                           9996
                                                                         149317
                                                                         100741
                                                                          25649
                                                                             27
                                                                            100
                                                                            900
                                                                            274
                                                                           9017
                                                                            375
                                                                           2312
                                                                           1527
                                                                           2073
                                                                           2030
                                                                          10103
                                                                         150922
                                                                         101823
                                                                          25925
                                                                             28
                                                                            101
                                                                            912
                                                                            277
                                                                           9114
                                                                            376
                                                                           2340
                                                                           1546
                                                                           2104
                                                                           2031
                                                                          10215
                                                                         152591
                                                                         102952
                                                                          26209
                                                                             28
                                                                            103
                                                                            922
                                                                            280
                                                                           9209
                                                                            377
                                                                           2368
                                                                           1567
                                                                           2131
                                                                           2032
                                                                          10328
                                                                         154280
                                                                         104098
                                                                          26493
                                                                             28
                                                                            104
                                                                            931
                                                                            283
                                                                           9286
                                                                            381
                                                                           2385
                                                                           1585
                                                                           2152
                                                                           2033
                                                                          10439
                                                                         155930
                                                                         105216
                                                                          26772
                                                                             28
                                                                            105
                                                                            942
                                                                            286
                                                                           9378
                                                                            385
                                                                           2405
                                                                           1609
                                                                           2174
                                                                           2034
                                                                          10538
                                                                         157420
                                                                         106225
                                                                          27024
                                                                             29
                                                                            106
                                                                            956
                                                                            290
                                                                           9493
                                                                            391
                                                                           2432
                                                                           1639
                                                                           2203
                                                                           2035
                                                                          10633
                                                                         158833
                                                                         107181
                                                                          27263
                                                                             29
                                                                            108
                                                                            969
                                                                            293
                                                                           9599
                                                                            396
                                                                           2457
                                                                           1669
                                                                           2232
                                                                           2036
                                                                          10724
                                                                         160194
                                                                         108102
                                                                          27494
                                                                             30
                                                                            109
                                                                            983
                                                                            296
                                                                           9698
                                                                            401
                                                                           2482
                                                                           1701
                                                                           2260
                                                                           2037
                                                                          10813
                                                                         161523
                                                                         109001
                                                                          27720
                                                                             30
                                                                            111
                                                                            996
                                                                            299
                                                                           9795
                                                                            405
                                                                           2508
                                                                           1733
                                                                           2288
                                                                           2038
                                                                          10901
                                                                         162835
                                                                         109888
                                                                          27944
                                                                             30
                                                                            113
                                                                           1009
                                                                            301
                                                                           9887
                                                                            409
                                                                           2532
                                                                           1766
                                                                           2315
                                                                           2039
                                                                          10983
                                                                         164062
                                                                         110717
                                                                          28153
                                                                             31
                                                                            114
                                                                           1021
                                                                            304
                                                                           9968
                                                                            413
                                                                           2553
                                                                           1794
                                                                           2342
                                                                           2040
                                                                          11055
                                                                         165135
                                                                         111441
                                                                          28338
                                                                             31
                                                                            115
                                                                           1034
                                                                            306
                                                                          10051
                                                                            416
                                                                           2573
                                                                           1822
                                                                           2371
                                                                           2041
                                                                          11155
                                                                         166628
                                                                         112449
                                                                          28594
                                                                             32
                                                                            117
                                                                           1047
                                                                            309
                                                                          10147
                                                                            420
                                                                           2596
                                                                           1849
                                                                           2402
                                                                           2042
                                                                          11256
                                                                         168135
                                                                         113466
                                                                          28852
                                                                             32
                                                                            118
                                                                           1060
                                                                            312
                                                                          10243
                                                                            424
                                                                           2620
                                                                           1876
                                                                           2435
                                                                           2043
                                                                          11357
                                                                         169655
                                                                         114490
                                                                          29115
                                                                             32
                                                                            120
                                                                           1074
                                                                            315
                                                                          10342
                                                                            428
                                                                           2646
                                                                           1901
                                                                           2470
                                                                           2044
                                                                          11460
                                                                         171189
                                                                         115523
                                                                          29380
                                                                             33
                                                                            121
                                                                           1087
                                                                            318
                                                                          10442
                                                                            432
                                                                           2672
                                                                           1925
                                                                           2507
                                                                           2045
                                                                          11564
                                                                         172737
                                                                         116567
                                                                          29647
                                                                             33
                                                                            123
                                                                           1101
                                                                            321
                                                                          10543
                                                                            436
                                                                           2698
                                                                           1950
                                                                           2544
                                                                           2046
                                                                          11668
                                                                         174299
                                                                         117620
                                                                          29916
                                                                             34
                                                                            124
                                                                           1115
                                                                            324
                                                                          10646
                                                                            440
                                                                           2725
                                                                           1975
                                                                           2581
                                                                           2047
                                                                          11774
                                                                         175875
                                                                         118683
                                                                          30187
                                                                             34
                                                                            126
                                                                           1129
                                                                            328
                                                                          10749
                                                                            445
                                                                           2751
                                                                           2001
                                                                           2619
                                                                           2048
                                                                          11880
                                                                         177465
                                                                         119756
                                                                          30460
                                                                             34
                                                                            127
                                                                           1143
                                                                            331
                                                                          10853
                                                                            449
                                                                           2778
                                                                           2028
                                                                           2656
                                                                           2049
                                                                          11988
                                                                         179069
                                                                         120838
                                                                          30735
                                                                             35
                                                                            129
                                                                           1158
                                                                            334
                                                                          10958
                                                                            453
                                                                           2805
                                                                           2055
                                                                           2695
                                                                           2050
                                                                          12096
                                                                         180688
                                                                         121931
                                                                          31013
                                                                             35
                                                                            131
                                                                           1172
                                                                            337
                                                                          11064
                                                                            458
                                                                           2832
                                                                           2083
                                                                           2733

Appendix B: Fuel Type and Regulatory Class Fractions for 1960-1981
As noted in the text, all the fuel type and regulatory class distributions in the SampleVehiclePopulation table for model year 1981 and earlier have not changed from MOVES2010b. Those fuel type distributions between 1960 and 1981 for each source type have been summarized in Table 18-1 and Table 18-2. Many of the data sources for the fuel type fractions are the same in MOVES2010b and MOVES2014. Truck diesel fractions in Table 18-1 are derived using a MOVES2010b sample vehicle counts dataset -- similar to the MOVES2014 one -- but with 1999 Polk vehicle registrations and the 1997 VIUS, except for refuse trucks and motor homes. We assumed 96 percent of refuse trucks were manufactured to run on diesel fuel in 1980 and earlier according to the average diesel fraction from VIUS across all model years. We also assumed that 15 percent of motor homes are diesel powered based on information from the Recreation Vehicle Industry Association (RVIA), as noted above in Section <IP_ADDRESS>.

                    Table 18-1 Diesel Fractions for Trucks*

                                  Source Type
                                  Model Year

                               Passenger Trucks
                                     (31)
                            Light Commercial Trucks
                                     (32)
                                 Refuse Trucks
                                     (51)
                              Single Unit Trucks
                                 (52 & 53)
                               Motor Homes (54)
                         Short-haul Combination Trucks
                                     (61)
                         Long-haul Combination Trucks
                                     (62)
                                  1960-1979
                                    0.0139
                                    0.0419
                                     0.96
                                    0.2655
                                     0.15
                                    0.9146
                                    1.0000
                                     1980
                                    0.0124
                                    0.1069
                                     0.96
                                    0.2950
                                     0.15
                                    0.9146
                                    1.0000
                                     1981
                                    0.0178
                                    0.0706
                                     0.96
                                    0.3245
                                     0.15
                                    0.9146
                                    1.0000
* All other trucks are assumed to be gasoline powered

Like in MOVES2010b, lacking both emission rate and population data we assume in MOVES2014 that all motorcycles will be gasoline powered, all intercity buses will be diesel powered over all model years, and all transit buses will be run on diesel from 1960 to 1981. School bus fuel type fractions are reused from MOBILE6, originally based on 1996 and 1997 Polk data. Passenger cars are split between gasoline and diesel for 1960-1981 using the MOVES2010b sample vehicle counts dataset.

            Table 18-2 Diesel Fractions for Non-truck Source Types*

                                  Source Type
                                  Model Year
Motorcycles
                                     (11)
                                Passenger Cars
                                     (21)
                                Intercity Buses
                                     (41)
                                 Transit Buses
                                     (42)
                               School Buses (43)
                                  1960-1974
                                       0
                                    0.0069
                                     1.000
                                     1.000
                                    0.0087
                                     1975
                                       0
                                    0.0180
                                     1.000
                                     1.000
                                    0.0087
                                     1976
                                       0
                                    0.0165
                                     1.000
                                     1.000
                                    0.0086
                                     1977
                                       0
                                    0.0129
                                     1.000
                                     1.000
                                    0.0240
                                     1978
                                       0
                                    0.0151
                                     1.000
                                     1.000
                                    0.0291
                                     1979
                                       0
                                    0.0312
                                     1.000
                                     1.000
                                    0.0460
                                     1980
                                       0
                                    0.0467
                                     1.000
                                     1.000
                                    0.0594
                                     1981
                                       0
                                    0.0764
                                     1.000
                                     1.000
                                    0.2639
            * All other vehicles are assumed to be gasoline powered

The 1960-1981 regulatory class distributions are difficult to represent succinctly, but they have been derived from the MOVES2010b sample vehicle counts dataset as well, with a few exceptions. Motorcycles (sourceTypeID 11 and regClassID 10) and passenger cars (sourceTypeID 21 and regClassID 20) have one-to-one relationships between source types and regulatory classes for all model years for both MOVES2010b and MOVES2014. Passenger trucks (sourceTypeID 31) and light commercial trucks (sourceTypeID 32) are split between fuel type and regulatory class (regClassID 30 and 40) as shown in Table 18-3.

Table 18-3 Percentage by regulatory class and fuel type for passenger trucks (sourceTypeID 31) and light commercial truck (sourceTypeID 32)

                             Passenger Trucks (31)
                         Light Commercial Trucks (32)

                                   Gasoline
                                    Diesel
                                   Gasoline
                                    Diesel
                                  Model Year
                                   LDT (30)
                                      LHD
                                     (40)
                                   LDT (30)
                                      LHD
                                     (40)
                                   LDT (30)
                                      LHD
                                     (40)
                                   LDT (30)
                                      LHD
                                     (40)
                                   1960-1966
                                      81%
                                      19%
                                      38%
                                      62%
                                      24%
                                      76%
                                      7%
                                      93%
                                     1967
                                      90%
                                      10%
                                      38%
                                      62%
                                      72%
                                      28%
                                      7%
                                      93%
                                     1968
                                      88%
                                      12%
                                      38%
                                      62%
                                      67%
                                      33%
                                      7%
                                      93%
                                     1969
                                     100%
                                      0%
                                      38%
                                      62%
                                      91%
                                      9%
                                      7%
                                      93%
                                     1970
                                      99%
                                      1%
                                      38%
                                      62%
                                      80%
                                      20%
                                      7%
                                      93%
                                     1971
                                      96%
                                      3%
                                      38%
                                      62%
                                      94%
                                      6%
                                      7%
                                      93%
                                     1972
                                      96%
                                      4%
                                      38%
                                      62%
                                      75%
                                      25%
                                      7%
                                      93%
                                     1973
                                      95%
                                      5%
                                      38%
                                      62%
                                      59%
                                      41%
                                      7%
                                      93%
                                     1974
                                      95%
                                      5%
                                      38%
                                      62%
                                      65%
                                      35%
                                      7%
                                      93%
                                     1975
                                      97%
                                      3%
                                      38%
                                      62%
                                      72%
                                      28%
                                      7%
                                      93%
                                     1976
                                      95%
                                      5%
                                      38%
                                      62%
                                      88%
                                      12%
                                      7%
                                      93%
                                     1977
                                      89%
                                      11%
                                      38%
                                      62%
                                      79%
                                      21%
                                      7%
                                      93%
                                     1978
                                      85%
                                      15%
                                      38%
                                      62%
                                      81%
                                      19%
                                      7%
                                      93%
                                     1979
                                      87%
                                      13%
                                      38%
                                      62%
                                      78%
                                      22%
                                      7%
                                      93%
                                     1980
                                      90%
                                      10%
                                      38%
                                      62%
                                      74%
                                      26%
                                      40%
                                      60%
                                     1981
                                      96%
                                      4%
                                      38%
                                      62%
                                      89%
                                      11%
                                      12%
                                      88%

The bus and motor home source types each have a single regulatory class distribution for all model years, as described in Section 1.1.1. The 1960-1981 regulatory class distributions for diesel-fueled single unit and combination trucks have been summarized in Table 18-4 below. All 1960-1981 gasoline-fueled single unit and combination trucks fall into the medium heavy-duty (MHD) regulatory class (regClassID 46).

Table 18-4 Percentage of MHD Trucks (regClassID 46) among Diesel-fueled Single Unit and Combination Trucks*

                                  Source Type
                                  Model Year
                                 Refuse Trucks
                                     (51)
                              Single Unit Trucks
                                  (52&53)
                            Short-haul Comb. Trucks
                                     (61)
                            Long-haul Comb. Trucks
                                     (62)
                                   1960-1972
                                     100%
                                      0%
                                      0%
                                      0%
                                     1973
                                     100%
                                      3%
                                      8%
                                      0%
                                     1974
                                      0%
                                      6%
                                      30%
                                      0%
                                     1975
                                      0%
                                      14%
                                      3%
                                      0%
                                     1976
                                      0%
                                      44%
                                      13%
                                      0%
                                     1977
                                      0%
                                      43%
                                      31%
                                      0%
                                     1978
                                      0%
                                      36%
                                      18%
                                      0%
                                     1979
                                      0%
                                      34%
                                      16%
                                      0%
                                     1980
                                      0%
                                      58%
                                      29%
                                      5%
                                     1981
                                      0%
                                      47%
                                      31%
                                      6%
    *For these source types, all remaining trucks are in the HHD regulatory class (regClassID 47).

Appendix C: 1990 Age Distributions
Motorcycles
The motorcycle age distributions are based on Motorcycle Industry Council estimates of the number of motorcycles in use, by model year, in 1990. However, data for individual model years starting from 1978 and earlier were not available. A logarithmic regression curve (R[2] value = 0.82) was fitted to available data, which was then used to extrapolate age fractions for earlier years beginning in 1978.
Passenger Cars
To determine the 1990 age fractions for passenger cars, we began with Polk NVPP(R) 1990 data on car registration by model year. However, this data presents a snapshot of registrations on July 1, 1990, and we needed age fractions as of December 31, 1990. To adjust the values, we used monthly data from the Polk new car database to estimate the number of new cars registered in the months July through December 1990. Model Year 1989 cars were added to the previous estimate of "Age 1" cars and Model Year 1990 and 1991 cars were added to the "Age 0" cars. Also the 1990 data did not detail model year for ages 15+. Hence, regression estimates were used to extrapolate the age fractions for individual ages 15+ based on an exponential curve (R[2] value =0.67) fitted to available data.
Trucks
For the 1990 age fractions for passenger trucks, light commercial trucks, refuse trucks, short-haul and long-haul single unit trucks and short-haul and long-haul combination trucks, we used data from the TIUS92 (1992 Truck Inventory and Use Survey) database. Vehicles in the TIUS92 database were assigned to MOVES source types as summarized in Table 19-118-118-117-1. Like VIUS97, TIUS92 does not include a model year field and records ages as 0 through 10 and 11-and-greater. Because we needed greater detail on the older vehicles, we followed the practice used for the 1999 fractions and determined the model year for some of the older vehicles by using the responses to the questions "How was the vehicle obtained?" (TIUS field "OBTAIN") and "When did you obtain this vehicle?" (TIUS field "ACQYR") and we adjusted the age-11-and-older vehicle counts by dividing the original count by model year by the fraction of the older vehicles that were coded as "obtained new."

     Table 19-1 VIUS 1997 Codes Used for Distinguishing Truck Source Types
Source Type
Axle Arrangement
Primary Area of Operation
Body Type
Major Use
Passenger Trucks
2 axle/4 tire (AXLRE= 1,5,6,7)
Any
Any
personal transportation (MAJUSE=20)
Light Commercial Trucks
2 axle/4 tire (AXLRE= 1,5,6,7)
Any
Any
any but personal transportation
Refuse Trucks
Single Unit (AXLRE=2-4,
8-16)
Off-road, local or short-range (AREAOP <=4)
Garbage hauler (BODTYPE=30)
Any
Single Unit Short-haul Trucks
Single Unit (AXLRE=2-4,
8-16)
Off-road, local or short-range (AREAOP<=4)
Any except garbage hauler
Any
Single Unit Long-haul Trucks
Single Unit (AXLRE=2-4,
8-16)
Long-range (AREAOP>=5)
Any
Any
Combination Short-haul Trucks
Combination (AXLRE>=17)
Off-road, local or medium (AREAOP<=4)
Any
Any
Combination Long-haul Trucks
Combination (AXLRE>=17)
Long-range (AREAOP>=5)
Any
Any

Intercity Buses
For 1990, we were not able to identify a data source for estimating age distributions of intercity buses. Because the purchase and retirement of these buses is likely to be driven by general economic forces rather than trends in government spending, we will use the1990 age distributions that were derived for short-haul combination trucks, as described above.
School Buses and Motor Homes
To determine the age fractions of School Buses and Motor Homes, we used information from the Polk TIP(R) 1999 database. School Bus and Motor Home counts were available by model year. Unlike the Polk data for passenger cars, these counts reflect registration at the end of the calendar year and, thus, did not require adjustment. We converted model year to age and calculated age fractions. Because we did not have access to 1990 data, these fractions were used for 1990.
Transit Buses
For 1990 Transit Bus age distributions, we used the MOBILE 6 age fractions since 1990 data on transit buses was not available from the Federal Transit Administration database. MOBILE 6 age fractions were based on fitting curves through a snapshot of vehicle registration data as of July 1, 1996, which was purchased from R.L. Polk Company. To develop a general curve, the 1996 model year vehicle populations were 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 25+. 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 1[st] of a given calendar year.
Both Weibull curve fitting and exponential curve fitting were used to create the 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 transit buses, 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 19-2 presents the equations used to create the age distribution and the years in which the equations were used.

      Table 19-2 Curve Fit Equations for Registration Distribution by Age
                                  Vehicle Age
                                   Equation
                                     1-17
                      y=3462*e-age17.1690947512.53214119
                                    18-25+
                            24987.0776*e-0.2000*age

Appendix D: Driving Schedules and SCC Mappings
SCC Mappings
The Source Classification Code (SCC) used before MOVES2014 do not cleanly map to the source types used by MOVES.  In the 10-digit SCC, the first seven digits (SCC7) indicate the vehicle classification. The SCC vehicle classifications were mapped to the source types used by MOVES by calculating the fraction VMT for each source type found in each SCC classification result in a national MOVES2010b run for calendar year 2011.  The factors calculated from the MOVES201b run are shown in .

Table 20-1 Mapping of Previous SCC Vehicle Classifications to MOVES Source Types for Calculation of Road Type Distributions
                                      SCC
                                  (7 digits)
Description
                                  Source Type
Description
                                2011 Fractions
                                    2201001
Gasoline Light-Duty Vehicles (Passenger Cars)
                                      21
 Passenger Car
                                                                       1.000000
                                    2201020
Gasoline Light-Duty Trucks (0-6,000 lbs. GVWR)
                                      31
 Passenger Truck
                                                                       0.779270
                                    2201020
Gasoline Light-Duty Trucks (0-6,000 lbs. GVWR)
                                      32
 Light Commercial Truck
                                                                       0.220730
                                    2201040
Gasoline Light-Duty Trucks (6,001-8,500 lbs. GVWR)
                                      31
 Passenger Truck
                                                                       0.779269
                                    2201040
Gasoline Light-Duty Trucks (6,001-8,500 lbs. GVWR)
                                      32
 Light Commercial Truck
                                                                       0.220731
                                    2201070
Gasoline Heavy-Duty Gasoline Vehicles (8501 lbs. and greater GVWR)
                                      31
 Passenger Truck
                                                                       0.450274
                                    2201070
Gasoline Heavy-Duty Gasoline Vehicles (8501 lbs. and greater GVWR)
                                      32
 Light Commercial Truck
                                                                       0.267803
                                    2201070
Gasoline Heavy-Duty Gasoline Vehicles (8501 lbs. and greater GVWR)
                                      42
 Transit Bus
                                                                       0.000664
                                    2201070
Gasoline Heavy-Duty Gasoline Vehicles (8501 lbs. and greater GVWR)
                                      43
 School Bus
                                                                       0.002476
                                    2201070
Gasoline Heavy-Duty Gasoline Vehicles (8501 lbs. and greater GVWR)
                                      51
 Refuse Truck
                                                                       0.000509
                                    2201070
Gasoline Heavy-Duty Gasoline Vehicles (8501 lbs. and greater GVWR)
                                      52
 Single Unit Short-haul Truck
                                                                       0.221958
                                    2201070
Gasoline Heavy-Duty Gasoline Vehicles (8501 lbs. and greater GVWR)
                                      53
 Single Unit Long-haul Truck
                                                                       0.030154
                                    2201070
Gasoline Heavy-Duty Gasoline Vehicles (8501 lbs. and greater GVWR)
                                      54
 Motor Home
                                                                       0.025802
                                    2201070
Gasoline Heavy-Duty Gasoline Vehicles (8501 lbs. and greater GVWR)
                                      61
 Combination Short-haul Truck
                                                                       0.000359
                                    2201080
Gasoline Motorcycles
                                      11
 Motorcycle
                                                                       1.000000
                                    2230001
Diesel Light-Duty Vehicles (Passenger Cars)
                                      21
 Passenger Car
                                                                       1.000000
                                    2230060
Diesel Light-Duty Trucks (0-8,500 lbs. GVWR)
                                      31
 Passenger Truck
                                                                       0.343599
                                    2230060
Diesel Light-Duty Trucks (0-8,500 lbs. GVWR)
                                      32
 Light Commercial Truck
                                                                       0.656401
                                    2230071
Diesel Class 2b Heavy-Duty Vehicles (8501-10,000 lbs. GVWR)
                                      31
 Passenger Truck
                                                                       0.364691
                                    2230071
Diesel Class 2b Heavy-Duty Vehicles (8501-10,000 lbs. GVWR)
                                      32
 Light Commercial Truck
                                                                       0.635309
                                    2230072
Diesel Class 3, 4 & 5 Heavy-Duty Vehicles (10,001-19,500 lbs. GVWR)
                                      31
 Passenger Truck
                                                                       0.305092
                                    2230072
Diesel Class 3, 4 & 5 Heavy-Duty Vehicles (10,001-19,500 lbs. GVWR)
                                      32
 Light Commercial Truck
                                                                       0.694908
                                    2230073
Diesel Class 6 & 7 Heavy-Duty Vehicles (19,501-33,000 lbs. GVWR)
                                      51
 Refuse Truck
                                                                       0.001726
                                    2230073
Diesel Class 6 & 7 Heavy-Duty Vehicles (19,501-33,000 lbs. GVWR)
                                      52
 Single Unit Short-haul Truck
                                                                       0.623978
                                    2230073
Diesel Class 6 & 7 Heavy-Duty Vehicles (19,501-33,000 lbs. GVWR)
                                      53
 Single Unit Long-haul Truck
                                                                       0.086570
                                    2230073
Diesel Class 6 & 7 Heavy-Duty Vehicles (19,501-33,000 lbs. GVWR)
                                      54
 Motor Home
                                                                       0.025294
                                    2230073
Diesel Class 6 & 7 Heavy-Duty Vehicles (19,501-33,000 lbs. GVWR)
                                      61
 Combination Short-haul Truck
                                                                       0.194650
                                    2230073
Diesel Class 6 & 7 Heavy-Duty Vehicles (19,501-33,000 lbs. GVWR)
                                      62
 Combination Long-haul Truck
                                                                       0.067783
                                    2230074
Diesel Class 8a & 8b Heavy-Duty Vehicles (33,001 lbs. and greater GVWR)
                                      51
 Refuse Truck
                                                                       0.008531
                                    2230074
Diesel Class 8a & 8b Heavy-Duty Vehicles (33,001 lbs. and greater GVWR)
                                      52
 Single Unit Short-haul Truck
                                                                       0.100296
                                    2230074
Diesel Class 8a & 8b Heavy-Duty Vehicles (33,001 lbs. and greater GVWR)
                                      53
 Single Unit Long-haul Truck
                                                                       0.013800
                                    2230074
Diesel Class 8a & 8b Heavy-Duty Vehicles (33,001 lbs. and greater GVWR)
                                      54
 Motor Home
                                                                       0.000328
                                    2230074
Diesel Class 8a & 8b Heavy-Duty Vehicles (33,001 lbs. and greater GVWR)
                                      61
 Combination Short-haul Truck
                                                                       0.323425
                                    2230074
Diesel Class 8a & 8b Heavy-Duty Vehicles (33,001 lbs. and greater GVWR)
                                      62
 Combination Long-haul Truck
                                                                       0.553619
                                    2230075
Diesel Buses
                                      41
 Intercity Bus
                                                                       0.430859
                                    2230075
Diesel Buses
                                      42
 Transit Bus
                                                                       0.122565
                                    2230075
Diesel Buses
                                      43
 School Bus
                                                                       0.446576

Driving Schedules
A key feature of MOVES is the capability to accommodate a number of drive schedules to represent driving patterns across source type, roadway type and average speed. For the national default case, MOVES2014 employs 49 drive schedules with various average speeds, mapped to specific source types and roadway types.

T19-3 below lists the driving schedules used in MOVES2014.   Some driving schedules are used for both restricted access (freeway) and unrestricted access (non-freeway) driving.  Some driving schedules are used for multiple source types or multiple road types where vehicle specific information was not available.

           Table 20-2 MOVES2014 Default Driving Schedule Statistics
                               drive schedule id
                              drive schedule name
                                   avg speed
                                   max speed
                                idle time (sec)
                            percent of time idling
                                     miles
                                  time (sec)
                                    minutes
                                     hours
                                                                            101
 LD Low Speed 1
                                                                            2.5
                                                                          10.00
                                                                            280
                                                                          46.5%
                                                                          0.419
                                                                         602.00
                                                                          10.03
                                                                          0.167
                                                                            153
 LD LOS E Freeway
                                                                           30.5
                                                                          63.00
                                                                              5
                                                                           1.1%
                                                                          3.863
                                                                         456.00
                                                                           7.60
                                                                          0.127
                                                                            158
 LD High Speed Freeway 3
                                                                           76.0
                                                                          90.00
                                                                              0
                                                                           0.0%
                                                                         12.264
                                                                         581.00
                                                                           9.68
                                                                          0.161
                                                                            201
 MD 5mph Non-Freeway
                                                                            4.6
                                                                          24.10
                                                                             85
                                                                          29.0%
                                                                          0.373
                                                                         293.00
                                                                           4.88
                                                                          0.081
                                                                            202
 MD 10mph Non-Freeway
                                                                           10.7
                                                                          34.10
                                                                             61
                                                                          19.6%
                                                                          0.928
                                                                         311.00
                                                                           5.18
                                                                          0.086
                                                                            203
 MD 15mph Non-Freeway
                                                                           15.6
                                                                          36.60
                                                                             57
                                                                          12.6%
                                                                          1.973
                                                                         454.00
                                                                           7.57
                                                                          0.126
                                                                            204
 MD 20mph Non-Freeway
                                                                           20.8
                                                                          44.50
                                                                             95
                                                                           9.1%
                                                                          6.054
                                                                        1046.00
                                                                          17.43
                                                                          0.291
                                                                            205
 MD 25mph Non-Freeway
                                                                           24.5
                                                                          47.50
                                                                             63
                                                                          11.1%
                                                                          3.846
                                                                         566.00
                                                                           9.43
                                                                          0.157
                                                                            206
 MD 30mph Non-Freeway
                                                                           31.5
                                                                          55.90
                                                                             54
                                                                           5.5%
                                                                          8.644
                                                                         988.00