EPA420-R-98-004
April 1998
Methodology for Modifying MOBILESb in the Tier 2 Study
John W. Koupal
Richard A. Rykowski
Office of Mobile Sources
U.S. Environmental Protection Agency
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1 INTRODUCTION
EPA was mandated by Congress under Section 202(1) of the Clean Air Act Amendments of 1990
to study the need for "Tier 2" emission standards for light-duty vehicles (LDVs) and light-duty
tracks (LDTs) which would increase the stringency of these standards relative to the "Tier 1"
standards implemented in 1994. A specifically mandated element of the Tier 2 study was that the
determination of the need for new standards be based on an evaluation of air quality, along with
technical feasibility and cost effectiveness. The overall focus of the air quality assessment in the
suidy1 is the number and population of geographic areas not in attainment with National Ambient
Air Quality Standards (NAAQS) for Ozone, Carbon Monoxide and Paniculate Matter currently
and in the future, and the contribution of light-duty vehicular emissions to overall emission
inventories. The latter element helps determine the extent to which tighter light-duty emission
standards can address the air quality problem in the nation's nonattainment areas.
The computer model MOBILE is used by EPA to estimate emission levels from on-highway
mobile sources, including light-duty vehicles and trucks, heavy duty trucks, and motorcycles.
MOBILES, the current version of MOBILE, was released in 1992 with subsequent minor
revisions made in 1993 (MOBILESa) and 1996 (MOBILESb). EPA is in the process, however,
of substantially revising the MOBILE model. MOBILE6, currently scheduled for release in
1999, will include revisions to many key areas impacting tailpipe emission estimates. In
piirticular, MOBELE6 will be updated to reflect major revisions to basic emission rates, the
impacts of aggressive driving and air conditioning emissions, revised fuel sulfur impacts on
newer technology vehicles, and recent trends in LDT sales and usage patterns. Because of these
changes, MOBILE6 emission estimates are expected to vary considerably from those in
MOBILES.
Because the differences between MOBILES and MOBILE6 will affect estimates of the light-duty
emission inventory, it was necessary to reflect these changes in the air quality assessment of the
Tier 2 study. Unfortunately MOBILE6, even in draft form, was not available for use in the study.
However, directional changes in the model are known for some of the primary components, and
in some cases, data which will be used to develop the MOBILE6 emission estimates are
available. In order to provide an estimate of MOBILE6 on-highway emission projections for the
Tier 2 study, therefore, a "modified MOBILESb" model was developed to serve as a surrogate
for MOBILE6. This model approximated the MOBILE6 revisions planned to address basic
emission rates, aggressive driving, air conditioning, fuel sulfur and fleet characteristics. This
report describes how estimates were developed for these components, how the model was
applied for the Tier 2 study air quality analysis, and how the modified model results compare to
MOBILESb.
A detailed description of the air quality needs assessment is contained in the Tier 2 Study, Appendix A
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2 TIER 2 STUDY AIR QUALITY APPROACH
The air quality assessment performed in the Tier 2 study was based on ozone modeling
performed as part of the Ozone Transport Assessment Group (OTAG) modeling process. In
OTAG, ozone projections for calender year 2007 under several control scenarios were developed
on a regional basis (by county or grid) over the entire 37 state OTAG region, enabling an
evaluation of ozone nonattainment areas which would result under each scenario. This work was
useful for the Tier 2 assessment since it projected future ozone nonattainment under a variety of
control scenarios. In particular, one scenario referred to as "Round 2 Run 5" closely simulates
the regional NOx control strategy proposed in the OTAG SIP Call NPRM, in addition to controls
for other sources at Clean Air Act mandated levels and other existing controls. This run used a
set of mobile sources control programs known as "Level 0", which included National LEV
(NLEV), Inspection/Maintenance (I/M), Reformulated Gasoline (RFG), and new heavy-duty
standards2.
In the Tier 2 study, Round 2 Run 5 results for all sources other than on-highway were used in
conjunction with modified MOBELESb on-highway inventory results. This allowed a revised
assessment of LDV and LDT contribution to overall inventory under existing controls3. The Tier
2 analysis focused on four basic combinations of on-highway mobile source control programs
(example cities/areas are shown in parenthesis):
a. Ozone Transport Region (OTR) NLEV with I/M and RFG (Northeast)
b. Non-OTR NLEV with I/M and RFG (Chicago)
c. Non-OTR NLEV with I/M and no RFG (Atlanta/Charlotte)
d. Non-OTR NLEV without I/M or RFG (Attainment)
Trie goal of the analysis presented in this report was to replicate as closely as possible the OTAG
"Level 0" control program using both MOBILESb and the modified MOBILESb model in order
to a) develop the revised Round 2 Run 5 on-highway mobile source estimates results for use in
the Tier 2 air quality analysis, and b) provide a basis for comparison between the two models.
E.H. Pechan & Associates, Inc., "Ozone Transport Assessment Group Emissions Inventory Development Report,
Volume 3: Projections and Controls". All OTAG program details and emission factors used in this analysis are from
this report.
3MOBILE5a was used for OTAG, while MOBELE5b was used for this analysis. Use of the latest release of
MOBILES was judged appropriate, and differences between the two models are not significant for the purpose of
this work.
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3 DEVELOPMENT OF MODIFIED MOBILESb INPUTS
3.1 Basic Emission Rates
Basic Emission Rates, or "BERs", are rates used by the MOBILE model to predict emission
levels from in-use vehicles over the Federal Test Procedure (FTP). BERs are established for
each vehicle class and model year to account for differences in emission standards and
technologies. To account for the impacts of deterioration as vehicles grow older, MOBILE BERs
are comprised of a baseline constant known as a "zero-mile level" (ZML) and a "deterioration
rate" (DR), which is a function of vehicle mileage. The BER is calculated by multiplying the DR
by mileage and adding the result to the ZML. The BER is then adjusted as appropriate to account
for numerous factors including speed, temperature and fuel properties, as well as benefits from
control programs such as I/M.
For the non-I/M case, BERs for Tier 0 light-duty vehicles proposed for MOBILE6 are
substantially lower than those for MOBILESb, particularly at higher mileages4. In large part this
is due to the elimination of the "kinked" deterioration rate at 50,000 miles, which resulted in
significant increases in MOBILESb emission estimates for vehicles above this mileage level.
MOBILE6 emission rates for Tier 1 and Low Emission Vehicles (LEVs) have not been
developed, but non-I/M rates for these vehicles will also likely be significantly lower than
MOBILESb. Because the MOBILE6 BERs are still under development, the new rates were
estimated beginning in the 1988 model year using emission rates from the California Air
Resources Board's CALIMFAC model5. The CALIMFAC rates are significantly lower than the
MOBILESb rates, and directionally capture the decrease expected to occur between MOBILESb
non-I/M rates and MOBILE6. As a general comparison, 1992 model year LDV non-I/M
CALIMFAC rates are shown with corresponding rates from MOBILESb in Figures 1-3 for HC,
CO and NOx. CALIMFAC's "LDV" rates were used for LDVs. CALDVIFAC's "LDT" category
includes all trucks below 6,000 pounds GVW, and were thus used for the MOBILE LDT1
(MOBLDT1) class6. The CALIMFAC MDV class includes trucks between 6,000 and 14,000
pounds, but is comprised primarily of those below 8,500 pounds, and were thus used directly for
MOBLDT2s.
"Composite Exhaust Emissions", EPA presentation at the October 1997 MOBILE6 workshop.
Revised BERs were implemented beginning in 1988 because of uncertainty at the time of this analysis as to how
early MOBILESb BERs would be revised.
^ic acronyms "MOBLDT1" and "MOBLDT2" are used in this report to denote the MOBILESb trucks definitions,
and avoid confusion with the certification definitions. MOBLDTls are trucks below 6,000 Ibs GVW (which
encompass certification LDT Is and 2s), while MOBLDT2s are trucks above this threshold (encompassing
certification LDTSs and 4s).
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Figure 1 - HC Basic Emission Rates: MOBILESb vs. CALIMFAC (no I/M)
2.5
40 60
Mileage (Thousands)
80
100
-0--M5 Tier 0 --o.-MS Tier 1 --*--M5 LEV —t— CAL Tier 0 —•— CAL Tier 1 —.^CAL LEV
Figure 2 - CO Basic Emission Rates: MOBILESb vs. CALIMFAC (no I/M)
=• 20 -
40 60
Mileage (Thousands)
80
100
-••0--M5 Tier 0 --Q--M5 Tier 1 --*--M5 LEV —•—CAL Tier 0 —it—CAL Tier 1 —*— CAL LEV
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Figure 3 - NOx Basic Emission Rates: MOBILESb vs. CALIMFAC (no I/M)
40 60
Mileage (Thousands)
80
100
•MSTierO --o-.MS Tier 1 --A--M5LEV
-CAL Tier 0
-CAL Tier 1
-CAL LEV
Modeling of an I/M program in MOBILESb can significantly vary the basic emission rates used
by the model. All I/M programs for Tier 0 and Tier 1 light-duty vehicles are based on "kinked"
bfiseline emission rates, and thus also result in higher "with I/M" emission levels than expected in
MQBILE6. However, for LEVs, application of maximum I/M in MOBILESb (as used in
OTAG) results in substantial emission reductions from the non-I/M case. Thus, for future
calender years in which the fleet is comprised primarily of LEVs, it is not certain that MOBILE6
will result in lower emission levels than would be predicted with MOBILESb when maximum
I/M is modeled. MOBILE6 I/M credits are currently under development, so a direct assessment
of these differences is not yet possible.
MOBILESb I/M credits were developed based on the MOBILESb emission rates, and cannot
appropriately be applied to the CALIMFAC non-I/M rates. Therefore, I/M benefits were handled
in the modified model by using the CALIMFAC "with I/M" emission rates (a more detailed
discussion of I/M program treatment is contained in Section 4.1). These rates reflect the benefits
of a dynamometer-based program, judged for the purposes of this analysis to be a reasonable
approximation of the "high enhanced" I/M program modeled under OTAG The CALIMFAC
I/M rates also include the full effects of On-Board Diagnostics (OBD H.) as appropriate by
vehicle class and model year, an element that will be incorporated into MOBILE6 as well. In
general the CALIMFAC "with I/M" DRs are approximately 30-40% lower than the CALIMFAC
non-I/M DRs (the ZMLs are the same for both cases).
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CALIMFAC rates could not be used directly beyond 1992 because of differences between the
California and Federal light-duty programs. California Tier 1 standards began phase-in in 1993,
while the Federal program did not start until 1994; in addition, the NLEV programs modeled for
both the OTR and Non-OTR scenarios do not correspond with California's LEV phase-in plan.
E.y-model year emission rates were therefore developed for 1993 and later by combining
CALIMFAC rates according to the applicable Federal Tier 1 and NLEV phase-in schedules.
This methodology required the estimation of "base" CALIMFAC Tier 0, Tier 1, TLEV and LEV
emission rates to allow proper combinations of standard level in each model year. The
CALIMFAC 1992 rates were used for base Tier 0, while base Tier 1 and LEV rates were
extracted from the CALIMFAC model7. TLEV rates were then estimated by interpolating the
Tier 1 and LEV rates based on the certification standards (this affected HC only, since TLEV CO
and NOx standards are unchanged from Tier 1). The estimated "with 1/M" base emission rates for
each standard level are shown in Table 1.
Table 1 - Estimated "With I/M" CALIMFAC Emission Rates - Grams/Mile
LDV
LOT
MDV
TierO
Tierl
TLEV
LEV
TierO
Tierl
TLEV
LEV
TierO
Tierl
HC
ZML
0.2980
0.1569
0.0729
0.0393
0.2961
0.1440
0.0588
0.0247
0.3001
0.1402
DR
0.0350
0.0142
0.0078
0.0052
0.0373
0.0161
0.0071
0.0035
0.0309
0.0160
CO
ZML
3.5112
1.1609
1.1609
0.0000
3.4550
1.0613
1.0613
0.0000
3.6745
0.9732
DR
0.5708
0.2438
0.2438
0.2797
0.6370
0.2614
0.2614
0.1787
1.1094
0.2634
NOx
ZML
0.3227
0.3091
0.3091
0.1790
0.5641
0.3009
0.3009
0.2980
0.7838
0.2976
DR
0.0224
0.0188
0.0188
0.0081
0.0422
0.0205
0.0205
0.0150
0.0499
0.0202
For LDVs and MOBLDTls, the Tier 1 phase-in schedule is 40% in 1994, 80% in 1995 and 100%
in 1996. For MOBLDT2s, the schedule is 50% in 1996 and 100% in 1997. For NLEV, which
applies only to LDVs and MOBLDTls, the appropriate phase-in of TLEV and LEVs depended
on whether the area being modeled was inside the OTR or not. Phase-in schedules for OTR and
non-OTR cases were duplicated from OTAG's Level 0 control package, and are shown in Table
2. For both the Tier 1 and NLEV phase-in periods, BERs for a given model year were developed
by combining the base BERs from Table 1 using the phase-in weighting; for example, 1994 LDV
rai:es were developed by combining base Tier 0 and Tier 1 rates using a 60/40 weighting. The
resulting base light-duty BERs for the Northeast and Attainment cases are shown in Appendix A.
This work was performed by Air Improvement Resource (AIR), Inc. under contract by AAMA. The base rates
mentioned were provided by AIR to EPA for the purpose of this analysis.
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Table 2 - NLEV Phase-In Percentages Used in OTAG Modeling (LDV & MOBLDT1)
Model
Year
1996
1997
1998
1999
2000
2001 & later
Ozone Transport Region (OTR)
Tierl
100
60
60
30
0
0
TLEV
0
40
40
40
40
0
LEV
0
0
0
30
60
100
Non-OTR
Tierl
100
100
100
100
100
0
LEV
0
0
0
0
0
100
O'TAG's Level 0 control package included alternate heavy-duty BERs which modeled the new
2.5 gram/bhp-hour NMHC+NOx standard. For consistency with the OTAG work, these BERs
were used for both MOBILESb and the modified model. The revised rates, implemented starting
in. 2004, are shown in Table 3.
Table 3 - Heavy Duty Basic Emission Rates Used in OTAG Modeling
Vehicle Type
HD Gas (HDGV)
HD Diesel
HDGas
HD Diesel
Pollutan
NOx
NOx
HC
HC
ZML (grams/BHP-hr)
1.660
1.840
0.277
0.257
DR (grams/BHP-hr/10,000
0.021
0.000
0.018
0.000
3.2 Off-Cycle
Off-cycle correction factors used in the modified MOBILESb model incorporated the effects of
uncontrolled aggressive driving and air conditioner operation, as well as the impact of the
Supplemental Federal Test Procedure (SKIP) requirements recently promulgated by EPA and
ARB8. EPA's rule applies to Tier 1 vehicles, and begins phase-in in 2000. ARB's rule applies
primarily to LEV/ULEVs, and begins phase-in in 2001. Both rules will dramatically reduce
uncontrolled off-cycle emissions, and will be accounted for in MOBILE6. However, under
NLEV, the ARB standards and phase-in will supersede the EPA rule, so treatment of benefits
from the ARB rule are of primary importance. The development of uncontrolled and controlled
aggressive driving and air conditioning correction factors are discussed in the following sections.
EPA: "Motor Vehicle Emissions Federal Test Procedure Revisions; Final Regulations", 61 FR 54851 October 22,
19S>6. ARB: "Public Hearing to Consider Adoption of New Certification Tests and Standards to Control Exhaust
Emissions from Aggressive Driving and Air-Conditioner Usage for Passenger Cars, Light-Duty Trucks, and
Medium-Duty Vehicles Under 8,501 Pounds Gross Vehicle Weight Rating", Staff Report, July 1997.
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3.2.1 Aggressive Driving
3.2.1.1 Uncontrolled Aggressive Driving
MOBILE6 will incorporate aggressive driving (i.e. driving at higher speeds and/or higher
acceleration rates than found on the conventional FTP) using speed correction factors based on
roadway type. MOBILE6's running basic emission rates (represented by the "running LA4",
developed to represent baseline running emission rates9) will be adjusted for each pollutant using
corrections developed separately for three fundamental roadway types: Freeway, Arterial and
Local. As planned, the MOBILE6 user will have the ability to specify combinations of roadway
type (expressed in terms of weightings for vehicle miles traveled, or VMT) and the speed
distribution on some roadway types to allow customized scenario modeling. In the absence of
such data, MOBILE6 will use default roadway and speed weightings developed from national
average information. Thus, the default aggressive driving corrections in MOBILE6 will reflect a
representative weighting of both roadway type and speed.
MOBILE6 roadway-based VMT and speed correction information were not available for this
analysis. As a surrogate, the modified MOBILESb correction factors were based on results from
California's "Unified" Cycle (LA92). This cycle was developed by ARB to reflect a
representative weighting of in-use speed and acceleration distributions based on driving patterns
observed in Los Angeles. The cycle, therefore, is similar in concept to the default weightings
which will be used in MOB1LE6, and is considered a reasonable approximation of the MOBILE6
aggressive driving approach.
The LA92 data used for this analysis were gathered on the same vehicle sample which will be
used to develop the MOBILE6 correction factors. The cycle was run with the vehicle warmed up
(i.e. without starts or soaks), so a direct comparison between the LA92 and running LA4 is
consistent with the handling of running aggressive driving correction factors in MOBILE6.
Running correction factors were developed by taking the ratio of sample average LA92 results to
sample average running LA4 results. Performing this analysis by certification standard (Tier 0
v:>. Tier 1) on normal emitters10 indicated that the factors for Tier 1 vehicles are higher than the
factors for Tier 0 vehicles for each pollutant. This difference was judged to be appropriate due to
the nature of off-cycle emissions relative to FTP performance. Vehicles complying with Tier 1
standards are optimized for compliance with the conventional FTP. Although it is likely that
"Running LA4" emissions were derived from the combination of emissions from Bag 2 and a 505 cycle run
warmed-up (i.e. without a soak). In MOBILE6, start and running emission will be treated separately, with the
running LA4 serving as the base running emission cycle to which speed correction factors are applied. More detail
on this can be found in MOBILE6 Report No. M6.STE.002, "The Determination of Hot Running Emissions from
FTP Bag Emissions".
10A "normal" emitter is defined under comparable MOBILE6 analyses as having Running LA4 emissions under 0.8
g/.mi for HC, 15.0 for CO and 2.0 for NOx. These outpoints are applied independently, so a vehicle could be a
normal emitter for one pollutant and a high emitter for another.
8
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some benefit from reductions over the conventional FTP will carry over to off-cycle emissions,
the same relative magnitude of reduction is not expected to carry over. For example, catalyst
sizing and loading are determined by emission performance over the FTP; these may increase for
Tier 1 compliance, resulting in some benefit off-cycle as well. However, because of the focus on
FTP performance, catalyst breakthrough off-cycle will occur on Tier 1 vehicles as with Tier 0
vehicles. Although lower than Tier 0 off-cycle emissions, the decrease in off-cycle emissions on
Tier 1 vehicles will not be of the same percentage as the decrease in FTP running emissions.
This would result in a larger aggressive driving correction on Tier 1 vehicles than for Tier 0
vehicles.
Tier 0 emission factors were generated based on certified Tier 0 normal emitters in the sample
(48 vehicles for HC, 57 for CO and 59 for NOx). Since only 12 Tier 1 vehicles were tested, an
attempt was made to increase the robustness of the Tier 1 sample by adding Tier 0 vehicles
which were considered equivalent to Tier 1 vehicles. Nine Tier 0 vehicles whose LA92 NMHC
and NOx emissions were at or below 70% of the Tier 1 FTP standard" were added to the
certified Tier 1 vehicle sample, creating a sample of 21 vehicles from which the final Tier 1
corrections were generated. The Tier 1 correction factors were also applied to LEVs since data
necessary to develop independent LEV correction factors is not available. The resulting running
correction factors for uncontrolled aggressive driving are shown in Table 4.
3,2.1.2 Post-SFTP Aggressive Driving
The impact of ARB's LEV SFTP rule was of primary importance for this analysis, since under
NLEV LDVs and MOBLDTls will be subjected to this requirement. For this analysis, however,
LEV benefits were based on reductions claimed by EPA for Tier 1 vehicles, so treatment of Tier
1 vehicles was first required. In EPA's SFTP rule, benefits for Tier 1 vehicles were estimated
based on a reduction in the incremental emission increase between overall in-use running
operation (based on a weighting of representative inventory cycles) and warmed-up FTP
conditions (represented by a running LA4) of 88% for NMHC, 72% for CO and 78% for NOx12.
The uncontrolled correction factors developed for the modified model using the LA92 and
running LA4 attempt to quantify the incremental increase in emissions due to aggressive driving
in a similar manner as the SFTP rule. Thus, SFTP benefits in the modified model were developed
for Tier 1 vehicles by applying the percent reductions from the SFTP rule to the uncontrolled
correction factors developed in the previous section. SFTP-controlled aggressive driving
correction factors for LEVs were developed by adjusting the Tier 1 reductions according to the
estimated stringency of ARB's US06 standards relative to EPA's standards, as detailed in
"Performing this analysis using Tier 0 vehicles whose FTP levels were below 70% of the Tier 1 FTP NMHC and
NOx standards reduced the Tier 1 NMHC correction by 5% relative to the LA92-based corrections, increased the
NOx correction factor by 15% and did not change the CO correction factor. The FTP-based approach is judged to
be more technically correct than the LA92 approach and will be used for future analyses.
12" Response to Comments for the Final Regulations to the Federal Test Procedure for Emissions from Motor
Vehicles", EPA Docket A-92-64 Item 5-C-l. Hereafter referred to as "SFTP Response to Comments".
9
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Appendix B. The SFTP-controlled aggressive driving correction factors for both Tier 1 vehicles
(pertinent for MOBLDT2s) and LEVs are shown in Table 4.
Table 4 - Aggressive Driving
Standard
Level
TierO
Tierl
LEV
HC*
Pre-SFTP
1.40
2.40
2.40
Post-SFTP
n/a
1.17
1.06
; Correction Factors (Running Only)
CO
Pre-SFTP
1.88
2.52
2.52
Post-SFTP
n/a
1.43
1.44
NOx
Pre-SFTP
1.57
1.63
1.63
Post-SFTP
n/a
1.14
1.04
* THC for Tier 0, NMHC for Tier 1 / LEV
3.2.2 Air Conditioning
3.2.2.1 Uncontrolled Air Conditioning
As proposed, running air conditioning correction factors in MOBILE6 will follow a similar
approach as the aggressive driving corrections. The model will rely on speed-based correction
factors for each pollutant to develop overall "full-usage" factors (meant to represent air
conditioning emissions when the A/C system is fully loaded) using the default or user-supplied
spieed distribution. The base correction factor will then be scaled down to reflect more
representative ambient conditions. The scaled-down air conditioning correction factor will then
be applied to the non-air conditioning emission level, including the effects of aggressive driving.
Unlike aggressive driving, air conditioning correction factors will also be developed for starts13.
The proposed MOBILE6 factors were not available for this analysis. Given the approach for
MOBELE6, the LA92 cycle was again judged appropriate to develop running air conditioning
correction factors for the modified model. A/C-on emission data over the LA92 was collected
over all vehicles from which the MOBILE6 corrections will be generated. Full-usage correction
factors were generated for each pollutant by dividing the sample average A/C-on results by the
sample average A/C-off results. Separate factors were generated for LDVs and LDTs (as is
proposed for MOBILE6) to account for differences in relative loading placed on cars and trucks
by the A/C system. Start emission factors were generated separately for LDVs and LDTs using
the ratio of cold start ST01 emissions.
For consistency with MOBILE6, the full-usage correction factors must be scaled down to reflect
more representative ambient conditions. The full-usage factors derived above were therefore
multiplied by a factor of 0.52 to represent the fraction of time that the A/C compressor is engaged
13,
'The proposed MOBILE6 air conditioning activity levels and correction factors can be found in two reports: "Air
Conditioning Activity Effects in MOBILE6", MOBILE6 Report No. M6.ACE.001, and "Air Conditioning
Co:.Tection Factors in MOBILE6", MOBILE6 Report No. M6.ACE.002.
10
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on a typical ozone exceedance day. This factor was developed as part of the SFTP rulemaking
based on temperature and humidity levels for typical ozone days cross-referenced with available
air conditioning activity data14. The resultant "typical" corrections are shown in Table 5.
3.2.2.2 Post-SFTP Air Conditioning
Estimates for the effect of SFTP control on air conditioning emissions were also based on EPA's
SFTP rule, and LEV benefits were again developed separately from Tier 1 benefits. In EPA's
rule, the NOx air conditioning standards for SC03 (the control cycle used for air conditioning
certification) were developed based on control of approximately 50% of the incremental
emissions due to air conditioner operation15. For the modified model it was assumed that this
reduction can be applied over the entire range of warmed-up driving, and the post-SFTP NOx
running correction factors were developed by reducing the uncontrolled corrections by 50%. For
start emissions, it was assumed that the SFTP rule would have no impact on uncontrolled
emissions, since control of A/C emissions was primarily ascribed to catalyst conversion
efficiency and EGR, both of which are not factors during cold starts. Therefore, post-SFTP start
A/C corrections were not changed for the uncontrolled corrections.
NMHC and CO emissions were also treated in accordance with EPA's SFTP rule. In cases
where NMHC emissions increased due to air conditioner operation, the SFTP-controlled.
correction factors were set to 1.0 under the assumption that excess fuel enrichment will be
eliminated on SFTP-compliant vehicles. If uncontrolled NMHC emissions were less than 1.0,
they were left unchanged (a reduction of HC emissions under A/C operation is frequently
observed, and is attributed to increased combustion temperature resulting from the added engine
load). The elimination of commanded enrichment expected under the SFTP rule was also
assumed to reduce uncontrolled CO emissions. However, because unavoidable loading increases
will still result in increased fuel consumption, the controlled CO correction factor was not
reduced to 1.0 but was instead equated with the increase in CO2 emissions (approximately 20%),
as planned for MOBILE6.
SFTP-controlled NOx correction factors for LEVs were developed according to the estimated
stringency of ARB's air conditioning (SC03) standards relative to EPA's standards, as detailed in
Appendix B. The controlled NMHC and CO factors for Tier 1 vehicles were applied to LEVs,
since the ARE and EPA requirements are similar in their intent to eliminate excess A/C
enrichment. The resultant correction factors for post-SFTP Tier 1 vehicles and LEVs are shown
in Table 5.
14SFTP Response to Comments
SFTP Response to Comments. It should be noted that the 50% percent reduction is based on a baseline emission
increase of 100%, a much higher increase then seen over the LA92 sample used for this analysis. The technical basi
for the standard is in fact to allow an increase of 50% from A/C off levels, which would result in a higher emissio
level than reflected by the post-SFTP estimates for this analysis. This issue will be reevaluated in the development
ofMOBILE6.
11
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Table 5 - Air Conditioning Correction Factors ("Typical" Conditions)
Vehicle
LDV**
LOT
Standard
TierO
Tierl
LEV
TierO
Tierl
LEV
LDV
LDT
TierO
Tierl
LEV
TierO
Tierl
LEV
HC*
Pre-SFTP
Post-SFTP
CO
Pre-SFTP
Post-SFTP
NOx
Pre-SFTP
Post-SFTP
Running
1.09
1.10
1.10
0.97
0.96
0.96
n/a
1.00
1.00
n/a
0.96
0.96
1.48
1.48
1.48
1.28
1.28
1.28
n/a
1.10
1.10
1.10
1.10
1.10
1.17
1.17
1.17
1.14
1.14
1.14
n/a
1.09
1.08
n/a
1.07
1.02
Start
0.98
0.98
0.98
1.02
1.02
1.02
0.98
0.98
0.98
1.02
1.02
1.02
0.97
0.97
0.97
1.09
1.09
1.09
0.97
0.97
0.97
1.09
1.09
1.09
1.14
1.14
1.14
1.10
1.10
1.10
1.14
1.14
1.14
1.10
1.10
1.10
* THC for Tier 0, NMHC for Tier 1 / LEV ** LDV also applies to Certification LDTls (< 3750 Ib)
3.2.3 Final Off-Cycle Corrections
For the modified MOBILESb model, aggressive driving and air conditioning corrections were
combined into a single "off-cycle" correction which was applied directly to the basic emission
rates discussed in Section 3.1. Development of the appropriate off-cycle corrections required the
combination of the aggressive driving and air conditioning factors and the translation of the
running and start-based factors into a combined FTP-based factor.
Since the running air conditioning correction factors represent the incremental increase of
emissions over all warmed-up driving as represented by the LA92 (the basis for aggressive
driving factors), combined off-cycle running factors were developed by multiplying the
aggressive driving and air conditioning running factors (from Tables 4 and 5) together. Since
only air conditioning also had start factors, these factors were carried over as the "combined" off-
cycle start factors. In order to convert the combined correction factors into the MOBILESb
definition of trucks, MOBLDT1 factors were developed by combining the "LDV/Certification
LDT1" and "LDT" corrections together based on a 30/70 weighting (this split was used in the
development of CALEvIFAC "LDT" emission rates). The "LDT" corrections were applied
directly for MOBLDT2s.
12
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The start and running off-cycle factors were then combined into an FTP-based factor using the
ninning/FTP fractions developed for the proposed MOBILE6 Tier 0 1990-93 PFILDV BERs
(see reference note 4). Since these splits are dependent on vehicle mileage, estimates of the
average in-use mileage for LDVs (68K miles), LDTls (81K miles) and LDT2s (100K miles)
v/ere used to establish the appropriate splits (the development of these average mileage levels is
discussed in Section 3.4.3). The combined start and running off-cycle factors were weighted
with the appropriate split (start fraction = 1 - running fraction) to derive the FTP-based off-cycle
correction factors. The running/FTP fractions are shown in Table 6, and the final FTP-based off-
cycle correction factors are shown in Table 7.
Table 6 - Running / FTP Fractions
Vehicle Class
LDV
MOBLDT1
MOBLDT2
Mileage
68,000
81,000
100,000
HC Fraction
0.48
0.51
0.55
CO Fraction
0.70
0.74
0.77
NOx Fraction
0.80
0.82
0.84
Table 7 - Final FTP-Based Off-Cycle Correction Factors
Vehicle
LDV
MOBLDT1
MOBLDT2
Standard
TierO
Tierl
LEV
TierO
Tierl
LEV
TierO
Tierl
LEV
HC*
Pre-SFTP
1.24
1.78
1.78
1.21
1.72
1.72
1.21
1.73
1.73
Post-SFTP
n/a
1.07
1.02
n/a
1.07
1.03
n/a
1.08
1.04
CO
Pre-SFTP
2.24
2.90
2.90
2.14
2.77
2.77
2.10
2.73
2.73
Post-SFTP
n/a
1.39
1.40
n/a
1.43
1.46
n/a
1.46
1.48
NOx
Pre-SFTP
1.70
1.75
1.75
1.68
1.74
1.74
1.68
1.74
1.74
Post-SFTP
n/a
1.22
1.13
n/a
1.20
1.11
n/a
1.20
1.10
* THC for Tier 0, NMHC for Tier 1 / LEV
Off-cycle correction factors were applied on a by-model year basis to account for Tier 1 phase-in
(since Tier 0 and Tier 1 corrections were different), and phase-in of the SFTP requirement.
Composite off-cycle corrections during the Tier 1 phase-in period were handled by weighting
Tier 0 and Tier 1 correction factors using the appropriate phase-in schedule. Since NLEV was
modeled in all cases, ARB's SFTP phase-in schedules were applied to LDVs and MOBLDTls
(25/50/85/100% starting in 2001), while EPA's phase-in was applied to MOBLDTZs
13
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(40/80/100% starting in 2002). Prior to the first year of applicable SFTP phase-in, the
uncontrolled correction factors were applied. During phase-in, the uncontrolled and controlled
off-cycle corrections were weighted according to the appropriate percentage in each year. The
controlled factors were applied to the first year of 100% compliance and afterwards. The
resultant off-cycle corrections were applied to the BERs (both the zero-mile level and
deterioration rates) starting from 1983 onward. 1983 was chosen as the first year of off-cycle
correction primarily because it was the oldest model year in the calender year 2007 scenarios;
application of the Tier 0 off-cycle corrections was judged appropriate this far back because three-
way catalyst technology was predominant in the light-duty fleet.
33 Fuel Effects
Data recently gathered on the impacts of fuel sulfur on LEV emissions indicates that as sulfur
levels increase, emissions increase much more than projected by MOBILESb. Sulfur corrections
for all vehicles are being revised for MOBILE6. Because the most significant change will occur
with LEVs, the modified MOBILESb model incorporated estimates only for LEVs based on the
new data. The following sections describe available emission data on the effect of sulfur on
LEV emissions, EPA's analyses of these data, and how the results of this analysis were
incorporated into the modified MOBILESb model.
3.3.1 Sulfur Test Programs
Two test programs were recently performed to assess the impact of fuel sulfur on LEV emissions.
One was performed by the Coordinating Research Council (CRC), made up of selected
avitomotive and oil companies, and the other was performed by automobile manufacturers who
are members of the American Automobile Manufacturers Association (AAMA) and the
Association of International Automobile Manufacturers (AIAM). The CRC study involved six
LDV models certified for sale in California in 1997. Two vehicles from each model type were
tested on seven fuels: California RFG with 40 ppm sulfur, California RFG doped to 150 ppm
sulfur, and national average conventional gasolines with doped sulfur levels of 40, 100, 150, 330,
and 600 ppm. The vehicles were leased from rental companies and averaged approximately
10,000 miles of use. The vehicles were tested in an as-received condition and with catalysts and
oxygen sensors aged to 100,000 miles. All testing was conducted at a single laboratory.
The AAMA/AIAM study consisted of 21 vehicles, each of different design: 13 LEV LDVs, one
LKV LDT1 (using the certification definition), six LEV LDT2s, one LEV MDV2 (LDT3), and
four ULEV LDVs. Some of the vehicle designs had been certified for sale in California, while
other design were deemed ready for certification and production. Each vehicle was tested by its
own manufacturer in order to maintain confidentiality. The resulting data was provided to an
independent statistician, who compiled the data. Five fuels were tested: the base fuel was a
California RFG with 40 ppm sulfur, and the other four fuels used the California RFG fuel doped
to 100, 150, 330, and 600 ppm. Figures 4 and 5 show average LDV NOx and NMHC emission
levels for both programs.
14
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Figure 4 - Average LDV NOx Emissions from LEV Sulfur Test Programs
AAMA/AIAM tested on Cal Ph2 fuel
CRC tested on *avg" Fed fuel & Cal Ph 2 at 40 ppm & 150 ppm
0 H 1 1 1 1 1 1 1———I 1 1 h
0 50 100 150 200 250 300 350 400 450 500 550 600
Sulfur (ppm)
Figure 5 - Average NMHC Emissions from LEV Sulfur Test Programs
AAMA/AIAM tested on Cal Ph2 fuel
CRC tested on 'avg* Fed fuel & Cal Ph 2 at 40 ppm & 150 ppm
o -i 1 1 1 1 1 1 1 1
0 50 100 150 200 250 300 350 400 450 500 550 600
Sulfur (ppm)
15
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3.3.2 LEV Correction Factors
For the modified MOBILESb model, correction factors for all pollutants were develop based on
the percentage increase from 40 ppm to 150 ppm (approximated Phase 2 RFG sulfur level) and
339 ppm (industry average non-RFG level as estimated by MOBILES) from the CRC and
AAMA/AIAM data. This required several steps starting from the raw test results from both
programs. The first step was to perform regressions of the emissions of each pollutant from all
die vehicles (separately for LDV/LDTls and LDT2/3s) at the same mileage and test program
versus sulfur level. Thus, for both vehicle classes, nine regressions were performed in all; three
for each pollutant, and three for each mileage/test program combination (CRC low and high
mileage, AAMA/AIAM high mileage). In each regression, each vehicle was assigned a dummy
variable to account for differences in their low-sulfur emission rates. The fitting of emission
versus sulfur depended on which form provided the greatest degree of correlation. For the CRC
low mileage data, the logarithm of emissions were regressed against sulfur. For the two high-
mileage cases, the logarithm of emissions were regressed against the logarithm of sulfur. Only
the CRC emission data using the Federal national average base fuel were included in the
regressions of the CRC data, in order to avoid the confounding effects of non-sulfur related
differences between the national average fuel and the Phase 2 California RFG fuel in the CRC
testing.
The next step was to account for mileage. As discussed in Section 3.4.3, the average in-use
mileages for LDVs, MOBLDTls and MOBLDT2s were estimated for this analysis to be 68K,
8 IK and 100K miles. The absolute emissions at each tested sulfur level were determined from
the two CRC regressions for each pollutant (low and high mileage). The emissions at the two
mileage points were then interpolated to estimate CRC-based emissions at the average in-use
mileages for LDVs, MOBLDTls and MOBLDT2s. The ratio of emissions at the average in-use
mileages to those at 100K miles were then determined for each sulfur level, pollutant and vehicle
type. These ratios were then applied to the 100K emission data from the AAMA/AIAM test
program to produce estimated emissions at the average in-use mileage.
The final step was to combine the emission estimates from the CRC and AAMA/AIAM test
programs at the average in-use mileages. A weighted average of the average emissions at each
sulfur test point from both programs was determined using the number of vehicles tested in each
program. The CRC data was assumed to represent six vehicles (as opposed to 12), because the
effect of sulfur on emissions from vehicles within the same model line were very similar. As
LDTs were not tested in the CRC program, projected sulfur impacts were determined only from
the AAMA/AIAM testing. The effect of increasing fuel sulfur content from 40 ppm to RFG and
conventional gasoline levels was determined by taking the ratio of the combined test results at
IfiO and 330 ppm sulfur to those at 40 ppm. The final results of this analysis are shown in Table
16
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8. The LDV/LDT1 corrections were used for LDVs and MOBLDTls 16. The LDT2/3 curve are
considered applicable to MOBLDT2s, but because under NLEV these vehicles are not held to
LEV standards, the LEV sulfur corrections were not applied to this truck class for this analysis.
Table 8 - Average LEV Sulfur Emission Increase From 40 ppm (percent)
Vehicle
Class
LDV
MOBLDT1
MOBLDT2
NMHC
150 ppm
15.7
16.5
11.3
330 ppm
30.3
29.5
18.3
CO
150 ppm
25.0
27.0
20.0
330 ppm
46.9
47.6
32.3
NOx
150 ppm
36.0
39.6
16.7
330 ppm
66.5
68.9
27.0
3.3.3 Incorporation into Modified MOBILESb
Fuel corrections in MOBILESb pertinent to this analysis are based on emission differences
between Indolene fuel and either baseline industry average (for the non-RFG case) or RFG.
While these differences are strongly driven by sulfur, the MOBILESb corrections include the
effects of non-sulfur influences such as RVP and fuel composition. It was therefore desirable in
the modified model to revise the sulfur impacts without altering the non-sulfur effects.
The MOBILESb fuel correction factors were derived from EPA's Complex Model. For this
analysis, the Complex Model was used to break the MOBILESb corrections into sulfur and
non-sulfur components. The revised LEV fuel corrections (for both conventional gasoline and
RFG) were then developed by multiplying the MOBILESb non-sulfur effects with the revised
sulfur corrections developed in the previous section, resulting in the revised LEV correction
factors (Table 9). These factors could not be input directly into the modified model, however,
because the existing MOBILESb fuel corrections were not disabled for this analysis.
Incorporation of the revised fuel corrections therefore needed to take into account the corrections
already imbedded in MOBILESb. This entailed entering corrections factors which, when
combined with the correction factors internal to MOBILES, would produce the desired ("target")
factors. The adjusted correction factors entered into the modified model were developed by
dividing the target correction factor by the MOBILESb correction, so the combined result of the
MOBILE5b corrections and the adjusted corrections would be the target corrections. Both the
target and adjusted correction factors are shown in Table 9.
16Hecause of the higher weighting of Certification LDT2s in the MOBLDT1 class, a weighted average of the
LDWCertification LDT1 and Certification LDT2 correction is judged to be more technically correct and will be
usud for future analysis. Based on the results presented in Figure 9 of Section 5, this correction would reduce the
2020 NOx sulfur contribution by 15-20%, and thus will not impact the directional results of the modified model
relative to MOBILESb.
17
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Table 9 - Final LEV Fuel Correction Factors (From Indolene)
Model
MOBILESb
Modified
MOBILESb
Correction
Total
Non-Sulfur
LDV Total Target
Adjusted
MOBLDT1 Total
Adjusted
HC
RFC
0.962
0.946
1.094
1.138
1.102
1.146
Conv
1.157
1.093
1.424
1.231
1.415
1.223
CO
RFG
0.905
0.867
1.084
1.198
1.101
1.217
Conv
1.087
0.948
1.393
1.281
1.399
1.287
NOx
RFG
1.079
1.030
1.401
1.299
1.438
1.333
Conv
1.160
1.032
1.718
1.481
1.743
1.503
The adjusted correction factors from Table 9 were applied multiplicatively to the basic emission
rates with off-cycle corrections; this assumes that the percent increase due to fuel quality
(primarily sulfur) observed over the FTP is applicable to aggressive driving and air conditioning
emissions as well as FTP-based emissions. The correction factor was applied on a by-model year
basis to years when LEVs were in the fleet. For years in which LEVs were not 100% of the fleet,
the fuel correction was scaled down using the appropriate LEV phase-in percentage.
The final "adjusted" basic emission rates used by the modified MOBILESb model, therefore,
consisted of the CALIMFAC BERs with off-cycle and fuel corrections applied. These rates,
shown for the Northeast and Attainment cases in Appendix A, were applied through the
MOBILESb input file using the NEWFLAG option17
3^4 Fleet Characteristics
Light truck sales have risen steadily over the past several years, significantly increasing market
share and VMT relative to light-duty vehicles. As a result, MOBILES underpredicts light-truck
market share, VMT and survival rates. Since trucks have higher emission rates than vehicles and
older trucks are dirtier than newer trucks, an increase in truck VMT and a flattened age
distribution will increase the relative contribution of older trucks to the overall inventory.
Overall, the changes in VMT mix and age distribution serve to increase light-duty inventory
estimates relative to MOBILESb.
EPA will update MOBILE6 to correct these shortfalls, but the updated estimates are not yet
available; therefore, related EPA work was used to develop updated fleet characteristics for this
analysis. Changes in fleet characteristics were addressed in two manners: 1) altering the
distribution of VMT between LDVs and LDTs, and 2) altering the age distributions for both
LDVs and LDTs to reflect higher survival rates. Both revisions are discussed in the following
sections.
17.
The MOBILESb code required modification to accommodate the large number of alternate rates used, as well as
alternate flex points (the point at which the deterioration rate changes) where applicable.
18
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3.4.1 Vehicle Miles Traveled
An EPA model characterizing the growth in relative light truck VMT was used as the basis for
the fleet-based modifications18 (referred to as the "VMT model"). This model combines sales
data and survival rates published by Oak Ridge National Laboratory (ORNL) to develop and
estimate relative gasoline vehicle and truck VMT out to 2020; the results indicate a greater
proportion of miles traveled by trucks than projected by MOBILESb. Revised MOBILESb VMT
fractions for each scenario year were developed from the VMT model by splitting the light truck
VMT projection in the given calender year into the two gasoline light truck classes used in
MOBILESb. This was done for all future calender years using an estimate from R.L. Polk for the
light truck fleet breakdown in 1996 (approximately 67% MOBLDTls and 33% MOBLDT2s)19.
The revised light-duty fractions were then renormalized within the gasoline light-duty share
afforded in MOBILESb, resulting in the VMT mix across all vehicles classes shown in Table 10.
These estimates were entered into MOBILESb using the VMFLAG command.
Table 10 - VMT Fractions
Year
2000
2005
2007
2010
2015
2020
VMT Split (%)
LDV
57.0
50.9
49.4
47.0
45.2
44.3
LDT
43.0
49.1
50.6
53.0
54.8
55.7
VMT Fractions (relative to all vehicle classes)
LDV
MOBILESb
0.614
0.600
0.595
0.589
0.581
0.575
Modified
0.503
0.450
0.435
0.415
0.398
0.391
MOBLDT1
MOBILESb
0.191
0.197
0.199
0.201
0.204
0.207
Modified
0.257
0.293
0.303
0.317
0.328
0.333
MOBLDT2
MOBILESb
0.086
0.087
0.087
0.088
0.089
0.089
Modified
0.122
0.139
0.144
0.150
0.156
0.158
3.4.2 Age Distribution
The survival rates used in the VMT model show a flatter distribution than projected by
MOBILESb, meaning that MOBILESb underpredicts the likelihood that older vehicles
(particularly trucks) will remain in operation. Revised age distributions were therefore
developed for LDVs, MOBLDTls and MOBLDT2s. ORNL survival rates (1990 for LDVs,
1979-1989 for LDTs) were used in conjunction with MOBILESb annual mileage accumulation
18German, "VMT and Emission Implications of Growth in Light Truck Sales", Presented at Air and Waste
Management Association Annual Conference, October 1997.
19
Accurex Environmental Corporation, "Update of Fleet Characterization Data for Use in MOBILE6", Report for
EPA, May 1997.
19
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rates to develop revised travel fraction estimates at each vehicle age20. MOBILESb's age
distribution (July) was then multiplied by the ratio of the revised travel fraction to the
MOBILESb travel fraction for each year, and the resultant "raw" distribution renormalized so
that it summed to one. As required by MOBILESb, age distributions for light-duty diesel
vehicles (LDDVs) and trucks (LDDTs) were set equal to their light-duty gasoline counterparts.
The revised distributions (and calculation methodology) are shown in Appendix C. These
distributions were implemented in the modified model using MOBILESb's MYRFLAG option.
3.4.3 Average In-Use Mileage
The average in-use mileages used in developing both the sulfur correction factors and the FTP-
based off-cycle corrections were developed by multiplying MOBILESb's cumulative mileage
accumulation rates for LDVs, LDTls and LDT2s by the revised travel fractions developed in the
previous section, and summing the result over all years. The resultant mileage levels were
68,000 for LDVs, 81,000 for LDTs and 100,000 for LDT2s. These mileage levels represent the
average in-use mileage for vehicles weighted by the contribution of overall VMT by each vehicle
age.
4 MODEL EXECUTION
Execution of the MOBILESb and modified MOBILESb models in a way which properly
evaluated the impact of the modifications and maintained consistency with the OTAG modeling
work required considerable manipulation of the input files for both models. Aside from the
manipulations described in Section 3 relating to adjusted BERs with off-cycle and sulfur
corrections (using the NEWFLAG option) and fleet characteristics (using the VMFLAG and
MYRFLAG options), required input file manipulations fell into three basic categories: treatment
of Inspection/Maintenance, NLEV phase-in and out year assumptions, and general model inputs.
Each are discussed below.
4,1 Inspection / Maintenance
Implementation of an enhanced I/M program was assumed for the I/M cases in this analysis.
OTAG's Round 2 Run 5 termed "high enhanced" I/M for pre-LEVs as an annual centralized
program using the IM240, with cutpoints of 0.8 g/mi HC, 15.0 g/mi CO and 2.0 g/mi NOx; for
LEVs, "maximum" I/M (under which vehicles are assumed to meet the applicable standards over
their full useful life) was assumed. Detailed program elements are listed in Table 11, and were
entered into the model using the IMFLAG option. However, because it was not appropriate to
use these inputs in conjunction with the CALIMFAC "with I/M" emission rates, they were only
used in the modified model for model years 1983 through 1987; starting in 1988, I/M effects in
the modified model were accounted for solely through the CALIMFAC rates.
20Travel Fraction, Year X = Annual Mileage in Year X / £ (Mileage * Survival Rate)
20
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An anti-tampering program was included as part of the enhanced I/M program as modeled in
OTAG's Round 2 Run 5 (Table 11). For MOBILESb this program was modeled directly, which
resulted in essentially zero tampering impact. For the modified model, however, the
CALIMFAC "with I/M" rates already incorporated the benefits of an anti-tampering program, so
application of the MOBILESb tampering adjustments to the CALIMFAC emission rates was not
appropriate. Therefore, to best represent the effects of an anti-tampering program in the modified
model, tampering effects were set to zero using TAMFLAG21. In terms of comparison between
the modified model and MOBILESb, this primarily impacted heavy-duty gasoline vehicles
(HDGVs), which the OTAG ATP program did not cover (leaving the tampering emissions intact
for these vehicles); as a result, the MOBILESb HDGV results are slightly higher than the
modified model results.
A.n evaporative pressure/purge test was also modeled as part of the enhanced I/M program under
OTAG (Table 11). Because none of the modifications made to MOBILESb affected evaporative
emissions, the pressure/purge parameters were not altered for the modified model.
Table 11 - I/M, Pressure/Purge, and Anti-Tampering Pro
Characteristic
Stringency
First Model Year
Last Model Year
Pre-1981 Waiver Rate
Post- 1981 Waiver Rate
Compliance Rate
Program Type
Inspection Frequency
Vehicle Types
Test Type
Cutpoints (HC/CO/NOx)
Inspections Performed
I/Ml
20%
1968
1985
3%
3%
96%
Centralized
Annual
LDGV/T1/T2
2500/Idle
none
I/M2
20%
1986
2020
3%
3%
96%
Centralized
Annual
LDGV/T1/T2
IM240
0.8/20.0/2.0
Pressure
1983
96%
Centralized
Annual
LDGV/T1/T2
»ram Assum
Purge
1986
96%
Centralized
Annual
LDGV/T1/T2
itions
ATP
1984
96%
Centralized
Annual
LDGV/T1/T2
ATP Only: Catalyst, Fuel Inlet Restrictor
4.2 NLEV
For MOBILESb, NLEV was modeled using the phase-in schedule used for OTAG for both the
OTR and non-OTR regions (shown in Table 2). In terms of the model, this requires setting the
PROMPT flag to "5" and specifying the phase-in schedule through an external file. For the
modified model, the impact of NLEV was handled through the weighting of the revised emission
This option was developed for internal EPA use, and is not allowed in SIP submissions.
21
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rates (as discussed in Section 3.1), so this option was not enacted. For the non-OTR case, 1996
emission rates were extended through 2000. For all cases, it was assumed that emission rates
v/ould stabilize at SFTP-controlled LEV levels in 2004 (the first year of 100% LEV SFTP
compliance) and remain constant through 2020. Tier 1 off-cycle correction factors were applied
to MOBLDT2s under the EPA phase-in schedule; full SFTP phase-in for these vehicles also
occurs in 2004, so emission rates were held constant from 2004 through 2020 for these vehicles
as well.
4.3 Other Model Inputs
Additional inputs used to run both models are discussed below:
Speed: An average speed of 24.6 mph was used for all model runs. This speed is the average
speed of the LA92 cycle, and was thus considered a reasonable estimate of average in-use speed.
This represented an approximation of the OTAG modeling, for which county-by-county speed
information was applied.
Temperature: A daily temperature range of 72° F to 96° F has been used in past EPA regulatory
analyses to approximate typical high ozone day temperatures. This again represented an
approximation of the OTAG work, which applied temperature data on a county-by-county basis.
However, because OTAG modeled time periods during which significant ozone episodes
occurred, this temperature range is a reasonable approximation of the OTAG temperatures.
F'uel RVP: To maintain consistency with OTAG, RVP was specified at 11.5 prior to 1992, and
8.7 for 1992 and later. For RFG cases, these levels were overridden by the RFG RVPs (Phase 1
and 2) used by MOBILESb on the appropriate implementation schedule.
Month: All runs were made in July to enable full RFG benefit.
HC: Additive methane offsets imbedded in MOBILE5b were not appropriate for the modified
MOBILESb THC emissions rates. While MOBILESb was run to produce NMHC results (using
the HCFLAG), the modified model was run to produce THC results. NMHC results from the
modified model were then calculated by applying the NMHC/THC ratio from MOBILESb to the
modified MOBILESb THC results for each vehicle class and scenario year.
5 RESULTS
For each of the four cases discussed in Section 2, MOBILESb and the modified MOBILESb were
run for a range of calendar years (2000, 2005, 2007, 2010, 2015 and 2020) to provide a direct
comparison between the models in the OTAG scenario year (2007), and observe how differences
between the models changed over time. Results for all four cases broken down by vehicle class
are contained in Appendix D.
22
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Figures 6 through 8 show NOx, NMHC, and CO emission factors from 2000 through 2020 for
both models in the Northeast and Attainment emission control scenarios. For the Northeast case,
the modified MOBILESb model projects higher emissions than MOBILESb over most years; the
two models converge for HC and CO towards 2020, while NOx in the modified model remains
higher. Comparison of the two models yield similar results for the other two control scenarios
v/hich include high enhanced I/M. For the Attainment case, the modified MOBILESb model
projects higher emissions relative to MOBILESb in the earlier years, but drops below
MOBILESb by 2010. The primary reason for the difference between the two cases is the absence
of high enhanced I/M; without this degree of I/M, MOBILESb projects that LEVs emit
substantially above their standards, and use of the CALIMFAC emission rates significantly
reduces base emissions.
Figure 6 - NOx Results for Northeast and Attainment Cases
3.0
2.5
0.0
2000
2005
2010
2015
2020
-MOBILESb (Northeast)
-MOBILESb (Attainment)
•Mod MOBILESb (Northeast)
-Mod MOBILESb (Attainment)
23
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Figure 7 - NMHC Results for Northeast and Attainment Cases
3.0
0.0
2000
30
25 -
I 20 -
t P-
15 4
in
I 10 +
HI
5 --
2000
2005
2010
2015
Figure 8 - CO Results for Northeast and Attainment Cases
2005
2010
2015
-MOBILESb (Northeast)
-MOBILESb (Attainment)
•o-.Mod MOBILESb (Northeast)
••a--Mod MOBILESb (Attainment)
2020
— •—MOBILESb (Northeast)
— *— MOBILESb (Attainment)
•-o.-Mod MOBILESb (Northeast)
••*--Mod MOBILESb (Attainment)
2020
24
-------
Figures 9 through 11 show results from the Northeast and Attainment cases in 2007 and 2020
broken down into the individual contribution of each of the four primary modifications (basic
emission rates, off-cycle, sulfur and fleet characteristics). These figures show that for both cases
in 2007, the off-cycle and fleet modifications are the primary drivers of the modified MOBILESb
increases for all pollutants. In 2020, increased fleet turnover of SFTP-compliant vehicles
decrease the off-cycle impact, while the prevalence of LEVs increases the relative sulfur impact
(primarily for NOx). These figures again illustrate the importance of I/M assumptions in
comparing the affect of the modifications. There is little difference in the contribution of base
emission rates between the modified and unmodified MOBILESb models when high enhanced
LM is present. However, without high enhanced I/M, the lower deterioration rates dominate the
other factors and the modified model projects lower overall emissions. It is also important to
note that the high light-duty NMHC contribution relative to non light-duty is driven largely by
evaporative emissions.
Figure 9 - NOx Breakdown
w
I 0.2 +
HI
0.0
2007 2007
Nonheast Northeast
MOBILESb Modified
2020
Northeast
MOBILESb
2020
Northeast
Modified
2007 2007
Attainment Attainment
MOBILESb Modified
2020 2020
Attainment Attainment
MOBILESb Modified
25
-------
Figure 10 - NMHC Breakdown
2007 2007
Norlheasl Northeast
MOBILESb Modified
2020 2020
Northeast Northeast
MOBILESb Modified
2007 2007
Attainment Attainment
MOBILESb Modified
2020 2020
Attainment Attainment
MOBILESb Modified
Figure 11 - CO Breakdown
16 -T
2007
Northeast
MOBILESb
2007
Northeast
Modified
2020 2020
Norlheasl Northeast
MOBILESb Modified
2007 2007
Attainment Attainment
MOBILESb Modified
2020 2020
Attainment Attainment
MOBILESb Modified
26
-------
Overall, these results indicate that the effects of off-cycle emissions, increased sulfur sensitivity,
increased LOT VMT and longer vehicle survival more than offset the effect of lower in-use
deterioration rates in the MOBILE model for nonattainment areas with high enhanced I/M
programs. To what extent these results are duplicated in MOBILE6 will of course depend on the
how different the final MOBILE6 basic emission rates are from the CALIMFAC rates. However,
because of the assumptions made by MOBILESb regarding high enhanced I/M, it is likely that
this trend will carry over to MOBILE6.
6 ACKNOWLEDGMENTS
The authors would like the thank the numerous individuals who provided effort, ideas and
information for this analysis: Dave Brzezinski of OMS provided input and guidance on several
MOBILESb issues, Connie Hart of OMS provided data analysis for aggressive driving effects,
Line Wehrly of OMS performed data analysis on the LEV sulfur dataset, John German provided
input on fleet characteristics and off-cycle issues, Jeff Long of ARB provided CALIMFAC basic
emission rates, and Tom Darlington and Dennis Kahlbaum of AER, Inc. provided CALIMFAC
rates by emission standard.
27
-------
Appendix A - Modified MOBILESb Emission Rates
Table A-l: LDV (Northeast Case)
Model
Year
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004-20
HC
Base
ZML DRl DR2
0.241 0.089 0.274
0.247 0.073 0.282
0.249 0.077 0.284
0.253 0.071 0.282
0.253 0.070 0.271
0.292 0.042
0.294 0.039
0.298 0.036
0.298 0.036
0.298 0.035
0.298 0.035
0.242 0.027
0.185 0.018
0.157 0.014
0.123 0.012
0.123 0.012
0.088 0.009
0.053 0.006
0.039 0.005
0.039 0.005
0.039 0.005
0.039 0.005
Adjusted
ZML DRl DR2
0.299 0.110 0.340
0.306 0.091 0.350
0.309 0.095 0.352
0.314 0.088 0.350
0.314 0.087 0.336
0.362 0.052
0.365 0.048
0.370 0.045
0.370 0.044
0.370 0.043
0.370 0.043
0.352 0.039
0.310 0.031
0.279 0.025
0.219 0.021
0.219 0.021
0.163 0.017
0.102 0.012
0.071 0.009
0.063 0.008
0.051 0.007
0.046 0.006
CO
Base
ZML DRl DR2
3.255 1.549 3.345
3.184 1.193 3.604
2.920 1.331 3.547
2.740 1.240 3.554
2.704 1.242 3.403
3.566 0.575
3.461 0.586
3.511 0.589
3.511 0.579
3.511 0.571
3.511 0.571
2.571 0.440
1.631 0.309
1.161 0.244
1.161 0.244
1.161 0.244
0.813 0.255
0.464 0.265
0.000 0.280
0.000 0.280
0.000 0.280
0.000 0.280
Adjusted
ZML DRl DR2
7.291 3.470 7.493
7.132 2.672 8.073
6.541 2.981 7.945
6.138 2.778 7.961
6.057 2.782 7.623
7.987 1.287
7.752 1.314
7.865 1.320
7.865 1.297
7.865 1.279
7.865 1.279
6.438 1.102
4.514 0.856
3.367 0.707
3.367 0.707
3.367 0.707
2.497 0.782
1.507 0.861
0.000 0.846
0.000 0.720
0.000 0.545
0.000 0.469
NOx
Base
ZML DRl DR2
0.578 0.067 0.199
0.465 0.079 0.224
0.469 0.078 0.210
0.425 0.082 0.214
0.442 0.078 0.213
0.510 0.042
0.404 0.032
0.323 0.024
0.323 0.023
0.323 0.022
0.323 0.022
0.317 0.021
0.312 0.020
0.309 0.019
0.309 0.019
0.309 0.019
0.270 0.016
0.231 0.012
0.179 0.008
0.179 0.008
0.179 0.008
0.179 0.008
Adjusted
ZML DRl DR2
0.983 0.114 0.338
0.791 0.134 0.381
0.797 0.133 0.357
0.723 0.139 0.364
0.751 0.133 0.362
0.867 0.072
0.686 0.055
0.549 0.041
0.549 0.040
0.549 0.038
0.549 0.038
0.546 0.036
0.543 0.034
0.541 0.033
0.541 0.033
0.541 0.033
0.515 0.030
0.477 0.026
0.371 0.017
0.335 0.015
0.284 0.013
0.263 0.012
-------
""e^d:x A = Modified MOBILES
ission Rates
Table A-2: MOBLDT1 (Northeast Case)
Model
Year
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004-20
HC
Base
ZML DRl DR2
0.820 0.150
0.700 0.150
0.408 0.077
0.392 0.071
0.377 0.070
0.294 0.048
0.294 0.047
0.294 0.044
0.296 0.039
0.296 0.037
0.296 0.037
0.235 0.029
0.174 0.020
0.144 0.016
0.110 0.013
0.110 0.013
0.074 0.009
0.038 0.005
0.025 0.004
0.025 0.004
0.025 0.004
0.025 0.004
Adjusted
ZML DRl DR2
0.992 0.182
0.847 0.182
0.494 0.093
0.474 0.086
0.456 0.085
0.355 0.058
0.355 0.057
0.356 0.053
0.358 0.048
0.358 0.045
0.358 0.045
0.333 0.041
0.282 0.033
0.248 0.028
0.189 0.022
0.189 0.022
0.133 0.016
0.072 0.009
0.044 0.006
0.039 0.006
0.032 0.005
0.029 0.004
CO
Base
ZML DRl DR2
12.580 1.460
9.430 1.460
5.074 1.331
4.642 1.240
4.358 1.242
3.712 0.778
3.716 0.764
3.629 0.716
3.498 0.658
3.455 0.637
3.455 0.637
2.498 0.487
1.540 0.337
1.061 0.261
1.061 0.261
1.061 0.261
0.743 0.237
0.425 0.212
0.000 0.179
0.000 0.179
0.000 0.179
0.000 0.179
Adjusted
ZML DRl DR2
26.921 3.124
20.180 3.124
10.858 2.848
9.934 2.654
9.326 2.658
7.944 1.664
7.953 1.634
7.766 1.532
7.485 1.408
7.393 1.364
7.394. 1.363
5.974 1.164
4.072 0.890
2.940 0.724
2.940 0.724
2.940 0.724
2.192 0.698
1.329 0.663
0.000 0.531
0.000 0.460
0.000 0.360
0.000 0.318
NOx
Base
ZML DRl DR2
1.6400 0.0300
1.1200 0.0700
1.1160 0.0780
0.9850 0.0820
0.8380 0.0780
0.5954 0.0583
0.5961 0.0555
0.5854 0.0506
0.5695 0.0450
0.5641 0.0422
0.5641 0.0422
0.4588 0.0335
0.3535 0.0248
0.3009 0.0205
0.3009 0.0205
0.3009 0.0205
0.3000 0.0189
0.2992 0.0172
0.2980 0.0150
0.2980 0.0150
0.2980 0.0150
0.2980 0.0150
Adjusted
ZML DRl DR2
2.755 0.050
1.882 0.118
1.875 0.131
1.655 0.138
1.408 0.131
1.000 0.098
1.001 0.093
0.983 0.085
0.957 0.076
0.948 0.071
0.948 0.071
0.782 0.057
0.611 0.043
0.524 0.036
0.524 0.036
0.524 0.036
0.574 0.036
0.625 0.036
0.629 0.032
0.566 0.028
0.478 0.024
0.441 0.022
-------
luiX n - mGuiiicu i»iv^i-»ii-/iiiju liiiiiiSSiuii rvtttca
Table A-3: MOBLDT2 (Northeast Case)
Model
Year
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004-20
HC
Base
ZML DR1 DR2
0.820 0.150
0.700 0.150
0.408 0.077
0.392 0.071
0.377 0.070
0.305 0.047
0.307 0.046
0.303 0.041
0.304 0.039
0.303 0.036
0.301 0.033
0.300 0.301
0.300 0.031
0.220 0.023
0.140 0.016
0.140 0.016
0.140 0.016
0.140 0.016
0.140 0.016
0.140 0.016
0.140 0.016
0.140 0.016
Adjusted
ZML DRl DR2
0.992 0.182
0.847 0.182
0.494 0.093
0.474 0.086
0.456 0.085
0.369 0.057
0.372 0.055
0.367 0.049
0.368 0.048
0.366 0.044
0.364 0.040
0.363 0.037
0.363 0.037
0.324 0.034
0.243 0.028
0.243 0.028
0.243 0.028
0.243 0.028
0.243 0.028
0.206 0.024
0.170 0.019
0.151 0.017
CO
Base
ZML DRl DR2
12.580 1.460
9.430 1.460
5.074 1.331
4.642 1.240
4.358 1.242
4.611 0.890
4.648 0.931
4.273 0.849
4.358 0.905
4.132 0.871
3.789 1.040
3.675 1.068
3.675 1.109
2.324 0.686
0.973 0.263
0.973 0.263
0.973 0.263
0.973 0.263
0.973 0.263
0.973 0.263
0.973 0.263
0.973 0.263
Adjusted
ZML DRl DR2
26.418 3.066
19.803 3.066
10.655 2.795
9.748 2.604
9.152 2.608
9.683 1.870
9.761 1.956
8.974 1.784
9.153 1.901
8.678 1.830
7.957 2.185
7.716 2.243
7.716 2.330
5.612 1.658
2.657 0.719
2.657 0.719
2.657 0.719
2.657 0.719
2.657 0.719
2.162 0.585
1.668 0.451
1.421 0.385
NOx
Base
ZML DRl DR2
1.640 0.030
1.120 0.070
1.116 0.078
0.985 0.082
0.838 0.078
0.791 0.059
0.800 0.058
0.788 0.056
0.789 0.056
0.787 0.054
0.785 0.052
0.784 0.051
0.784 0.050
0.541 0.035
0.298 0.020
0.298 0.020
0.298 0.020
0.298 0.020
0.298 0.020
0.298 0.020
0.298 0.020
0.298 0.020
Adjusted
ZML DRl DR2
2.755 0.050
1.882 0.118
1.875 0.131
1.655 0.138
1.408 0.131
1.329 0.099
1.345 0.097
1.324 0.094
1.326 0.094
1.323 0.091
1.318 0.087
1.317 0.085
1.317 0.084
0.925 0.060
0.518 0.035
0.518 0.035
0.518 0.035
0.518 0.035
0.518 0.035
0.454 0.031
0.389 0.026
0.357 0.024
-------
Appendix A - Modified MOBILESb Emission Rates
Table A-4: LDV (Attainment Case)
Model
Year
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004-20
HC
Flex
5.00
5.00
5.00
5.00
5.00
9.68
9.68
10.55
10.55
10.55
10.55
12.49
14.42
15.39
15.39
15.39
15.39
15.39
15.39
15.39
15.39
15.39
Base
ZM DRl DR2
0.241 0.089 0.274
0.247 0.073 0.282
0.249 0.077 0.284
0.253 0.071 0.282
0.253 0.070 0.271
0.292 0.078 0.022
0.294 0.076 0.023
0.298 0.074 0.014
0.298 0.074 0.014
0.298 0.074 0.014
0.298 0.074 0.014
0.242 0.054 0.021
0.185 0.034 0.028
0.157 0.025 0.032
0.157 0.025 0.032
0.157 0.025 0.032
0.157 0.025 0.032
0.157 0.025 0.032
0.039 0.009 0.012
0.039 0.009 0.012
0.039 0.009 0.012
0.039 0.009 0.012
Adjusted
ZML DRl DR2
0.299 0.110 0.340
0.306 0.091 0.350
0.309 0.095 0.352
0.314 0.088 0.350
0.314 0.087 0.336
0.362 0.097 0.027
0.365 0.094 0.029
0.370 0.092 0.017
0.370 0.092 0.017
0.370 0.092 0.017
0.370 0.092 0.017
0.352 0.079 0.031
0.310 0.058 0.047
0.279 0.044 0.057
0.279 0.044 0.057
0.279 0.044 0.057
0.279 0.044 0.057
0.279 0.044 0.057
0.077 0.018 0.023
0.068 0.016 0.021
0.055 0.013 0.017
0.049 0.011 0.015
CO
rlex
5.00
5.00
5.00
5.00
5.00
12.12
12.12
12.12
12.12
12.12
12.12
14.57
17.02
18.25
18.25
18.25
18.25
18.25
18.25
18.25
18.25
18.25
Base
ZML DRl DR2
3.255 1.549 3.345
3.184 1.193 3.604
2.920 1.331 3.547
2.740 1.240 3.554
2.704 1.242 3.403
3.566 1.237 0.670
3.461 1.272 0.629
3.511 1.268 0.574
3.511 1.268 0.574
3.511 1.268 0.574
3.511 1.268 0.574
2.571 0.917 0.536
1.631 0.566 0.498
1.161 0.391 0.480
1.161 0.391 0.480
1.161 0.391 0.480
1.161 0.391 0.480
1.161 0.391 0.480
0.000 0.482 0.986
0.000 0.482 0.986
0.000 0.482 0.986
0.000 0.482 0.986
Adjusted
ZML DRl DR2
7.291 3.470 7.493
7.132 2.672 8.073
6.541 2.981 7.945
6.138 2.778 7.961
6.057 2.782 7.623
7.987 2.772 1.501
7.752 2.849 1.408
7.865 2.840 1.286
7.865 2.840 1.286
7.865 2.840 1.286
7.865 2.840 1.286
6.438 2.296 1.342
4.514 1.567 1.380
3.367 1.133 1.391
3.367 1.133 1.391
3.367 1.133 1.391
3.367 1.133 1.391
3.367 1.133 1.391
0.000 1.560 3.191
0.000 1.329 2.717
0.000 1.004 2.053
0.000 0.865 1.769
NOx
Flex
5.00
5.00
5.00
5.00
5.00
10.55
10.55
10.55
10.55
10.55
10.55
11.74
12.92
13.52
13.52
13.52
13.52
13.52
13.52
13.52
13.52
13.52
Base
ZML DRl DR2
0.578 0.067 0.199
0.465 0.079 0.224
0.469 0.078 0.210
0.425 0.082 0.214
0.442 0.078 0.213
0.510 0.081 0.023
0.404 0.064 0.015
0.323 0.052 0.012
0.323 0.052 0.012
0.323 0.052 0.012
0.323 0.052 0.012
0.317 0.042 0.015
0.312 0.032 0.019
0.309 0.028 0.021
0.309 0.028 0.021
0.309 0.028 0.021
0.309 0.028 0.021
0.309 0.028 0.021
0.179 0.012 0.010
0.179 0.012 0.010
0.179 0.012 0.010
0.179 0.012 0.010
Adjusted
ZML DRl DR2
0.983 0.114 0.338
0.791 0.134 0.381
0.797 0.133 0.357
0.723 0.139 0.364
0.751 0.133 0.362
0.867 0.138 0.038
0.686 0.109 0.026
0.549 0.088 0.020
0.549 0.088 0.020
0.549 0.088 0.020
0.549 0.088 0.020
0.546 0.072 0.026
0.543 0.056 0.033
0.541 0.048 0.037
0.541 0.048 0.037
0.541 0.048 0.037
0.541 0.048 0.037
0.541 0.048 0.037
0.423 0.029 0.023
0.382 0.026 0.021
0.324 0.022 0.018
0.300 0.020 0.017
-------
Appendix A - Modified MOBILESb Emission Rates
Table A-4: MOBLDT1 (Attainment Case)
Model
Year
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004-20
HC
Flex
9.21
9.21
9.21
.9.21
9.21
9.21
11.83
14.45
15.76
15.76
15.76
15.76
15.76
15.76
15.76
15.76
15.76
Base
ZM DRl DR2
0.820 0.150
0.700 0.150
0.408 0.077
0.392 0.071
0.377 0.070
0.294 0.085 0.031
0.294 0.086 0.031
0.294 0.083 0.032
0.296 0.080 0.032
0.296 0.079 0.032
0.296 0.079 0.032
0.235 0.058 0.035
0.174 0.037 0.038
0.144 0.026 0.039
0.144 0.026 0.039
0.144 0.026 0.039
0.144 0.026 0.039
0.144 0.026 0.039
0.025 0.006 0.009
0.025 0.006 0.009
0.025 0.006 0.009
0.025 0.006 0.009
Adjusted
ZML DRl DR2
0.992 0.182
0.847 0.182
0.494 0.093
0.474 0.086
0.456 0.085
0.355 0.103 0.038
0.355 0.103 0.038
0.356 0.101 0.038
0.358 0.096 0.039
0.358 0.095 0.039
0.358 0.095 0.039
0.333 0.082 0.049
0.282 0.060 0.061
0.248 0.045 0.067
0.248 0.045 0.067
0.248 0.045 0.067
0.248 0.045 0.067
0.248 0.045 0.067
0.047 0.011 0.017
0.042 0.010 0.015
0.034 0.008 0.012
0.031 0.007 0.011
CO
171 __,
i1 lex
11.04
11.04
11.04
11.04
11.04
11.04
13.83
16.62
18.02
18.02
18.02
18.02
18.02
18.01
18.01
18.01
18.01
Base
ZML DRl DR2
12.580 1.460
9.430 1.460
5.074 1.331
4.642 1.240
4.358 1.242
3.712 1.425 0.708
3.716 1.427 0.706
3.629 1.391 0.761
3.498 1.346 0.845
3.455 1.330 0.872
3.455 1.330 0.872
2.497 0.958 1.033
1.540 0.587 1.193
1.061 0.401 1.273
1.061 0.401 1.273
1.061 0.401 1.273
1.061 0.401 1.273
1.061 0.401 1.273
0.000 0.296 1.613
0.000 0.296 1.613
0.000 0.296 1.613
0.000 0.296 1.613
Adjusted
ZML DRl DR2
26.92 3.124
20.18 3.124
10.85 2.848
9.934 2.654
9.326 2.658
7.944 3.050 1.515
7.953 3.053 1.510
7.766 2.978 1.629
7.485 2.881 1.808
7.393 2.847 1.867
7.393 2.847 1.867
5.973 2.293 2.470
4.072 1.551 3.154
2.940 1.110 3.527
2.940 1.110 3.527
2.940 1.110 3.527
2.940 1.110 3.527
2.940 1.110 3.527
0.000 0.931 5.071
0.000 0.807 4.391
0.000 0.632 3.439
0.000 0.557 3.031
NOx
rlex
11.04
11.04
11.04
11.04
11.04
11.04
11.96
12.88
13.34
13.34
13.34
13.34
13.34
13.34
13.34
13.34
13.34
Base
ZML DRl DR2
1.640 0.030
1.120 0.070
1.116 0.078
0.985 0.082
0.838 0.078
0.595 0.103 0.033
0.596 0.104 0.033
0.585 0.099 0.028
0.570 0.092 0.021
0.564 0.089 0.019
0.564 0.089 0.019
0.459 0.065 0.021
0.354 0.041 0.024
0.301 0.029 0.025
0.301 0.029 0.025
0.301 0.029 0.025
0.301 0.029 0.025
0.301 0.029 0.025
0.298 0.022 0.020
0.298 0.022 0.020
0.298 0.022 0.020
0.298 0.022 0.020
Adjusted
ZML DRl DR2
2.755 0.050
1.882 0.118
1.875 0.131
1.655 0.138
1.408 0.131
1.000 0.174 0.055
1.001 0.174 0.056
0.983 0.166 0.048
0.957 0.154 0.036
0.948 0.150 0.032
0.948 0.150 0.032
0.782 0.111 0.036
0.611 0.071 0.041
0.524 0.050 0.043
0.524 0.050 0.043
0.524 0.050 0.043
0.524 0.050 0.043
0.524 0.050 0.043
0.709 0.052 0.047
0.638 0.047 0.042
0.539 0.039 0.036
0.497 0.036 0.033
-------
A _____ IS— A TlyC-J'K-.J
. - iviuuiucu
ivauts
Table A-6: MOBLDT2 (Attainment Case)
Model
Year
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004-20
HC
Flex
10.01
10.01
10.01
10.01
10.01
10.01
10.01
10.01
12.70
15.39
15.39
15.39
15.39
15.39
15.39
15.39
15.39
Base
ZM DRl DR2
0.820 0.150
0.700 0.150
0.408 0.077
0.392 0.071
0.377 0.070
0.305 0.113 0.014
0.307 0.115 0.014
0.303 0.106 0.016
0.304 0.108 0.015
0.303 0.102 0.016
0.301 0.094 0.018
0.300 0.092 0.019
0.300 0.092 0.019
0.220 0.059 0.027
0.140 0.027 0.035
0.140 0.027 0.035
0.140 0.027 0.035
0.140 0.027 0.035
0.140 0.027 0.035
0.140 0.027 0.035
0.140 0.027 0.035
0.140 0.027 0.035
Adjusted
ZML DRl DR2
0.992 0.182
0.847 0.182
0.494 0.093
0.474 0.086
0.456 0.085 .
0.369 0.137 0.017
0.372 0.140 0.017
0.367 0.128 0.019
0.368 0.130 0.018
0.366 0.124 0.020
0.364 0.114 0.022
0.363 0.111 0.023
0.363 0.111 0.023
0.324 0.087 0.039
0.243 0.047 0.060
0.243 0.047 0.060
0.243 0.047 0.060
0.243 0.047 0.060
0.243 0.047 0.060
0.206 0.040 0.051
0.170 0.033 0.042
0.151 0.029 0.037
CO
171--,
flex
10.98
10.98
10.98
10.98
10.98
10.98
10.98
10.98
14.74
18.50
18.50
18.50
18.50
18.50
18.50
18.50
18.50
Base
ZML DRl DR2
12.580 1.460
9.430 1.460
5.074 1.331
4.642 1.240
4.358 1.242
4.611 1.871 0.377
4.648 1.889 0.371
4.273 1.745 0.528
4.358 1.777 0.490
4.132 1.693 0.591
3.789 1.566 0.746
3.675 1.523 0.797
3.675 1.523 0.797
2.324 0.969 0.877
0.973 0.416 0.958
0.973 0.416 0.958
0.973 0.416 0.958
0.973 0.416 0.958
0.973 0.416 0.958
0.973 0.416 0.958
0.973 0.416 0.958
0.973 0.416 0.958
Adjusted
ZML DRl DR2
26.41 3.066
19.80 3.066
10.65 2.795
9.748 2.604
9.152 2.608
9.683 3.928 0.791
9.761 3.967 0.780
8.974 3.665 1.109
9.153 3.732 1.029
8.678 3.556 1.242
7.957 3.288 1.566
7.716 3.198 1.674
7.716 3.198 1.674
5.612 2.341 2.119
2.657 1.134 2.614
2.657 1.134 2.614
2.657 1.134 2.614
2.657 1.134 2.614
2.657 1.134 2.614
2.162 0.923 2.128
1.668 0.712 1.641
1.421 0.607 1.398
NOx
171 „„
Hex
10.98
10.98
10.98
10.98
10.98
10.98
10.98
10.98
12.21
13.45
13.45
13.45
13.45
13.45
13.45
13.45
13.45
Base
ZML DRl DR2
1.640 0.030
1.120 0.070
1.116 0.078
0.985 0.082
0.838 0.078
0.791 0.108 0.040
0.800 0.109 0.042
0.788 0.107 0.033
0.789 0.107 0.035
0.787 0.107 0.030
0.785 0.107 0.023
0.784 0.107 0.020
0.784 0.107 0.020
0.541 0.068 0.021
0.298 0.030 0.022
0.298 0.030 0.022
0.298 0.030 0.022
0.298 0.030 0.022
0.298 0.030 0.022
0.298 0.030 0.022
0.298 0.030 0.022
0.298 0.030 0.022
Adjusted
ZML DRl DR2
2.755 0.050
1.882 0.118
1.875 0.131
1.655 0.138
1.408 0.131
1.329 0.181 0.068
1.345 0.182 0.070
1.324 0.180 0.056
1.326 0.180 0.059
1.323 0.180 0.051
1.318 0.179 0.038
1.317 0.179 0.034
1.317 0.179 0.034
0.925 0.116 0.036
0.518 0.051 0.038
0.518 0.051 0.038
0.518 0.051 0.038
0.518 0.051 0.038
0.518 0.051 0.038
0.454 0.045 0.033
0.389 0.039 0.028
0.357 0.035 0.026
-------
Appendix B: Methodology for Developing LEV SFTP Benefits
The determination of LEV SFTP benefits was based on an assessment of the stringency of
ARB's SFTP standards relative the EPA's standards. For US06, the basis for determining the
relative stringency of the ARB and EPA standards was a comparison between the US06
standards and an approximation of the applicable "running" FTP standards. Running FTP
standards were estimated by multiplying the 50K FTP standards (NMHC+NOx and CO) by a
running/FTP factor of 0.65, calculated based on start/running fractions from MOBILE6 Tier 0
LDV BERs proposed at the October 1997 MOBILE6 workshop. Because ARB's US06
standards are established at 4K miles, projection of these standards to 50K was necessary for the
analysis. This was done using the appropriate CALDvIFAC "with I/M" deterioration rates.
NMHC and NOx emissions were estimated from the NMHC+NOx standard using a split of 0.14
NMHC / 0.86 NOx, which was the basis of EPA's NMHC+NOx US06 standard. NMHC and
NOx emissions were projected separately to 50K, then recombined. The resultant 50K US06
"standards" were then ratioed with the estimated running FTP "standards" (NMHC+NOx and
CO) for both EPA and ARB, with the results shown in Table B-l. The relative stringency of the
E'.PA and ARB standards was compared using these ratios, and the Tier 1 benefits adjusted
accordingly (by adjusting the "remainder" of off-cycle emissions allowed by EPA's rule, as
detailed in Table B-l) to generate controlled correction factors for LEVs.
F'or air conditioning, only the running NOx correction factors for LEVs were developed in this
manner. The relative stringency of ARB's SC03 NOx standard was compared to EPA's Tier 1
standard relative to "running FTP" standards. ARB's standards were estimated to result in
slightly more relative benefit than assigned by EPA for LDV's, but substantially more for LDTs;
this is because ARB's a/C standards for LDTs were purposefully more stringent than the
methodology used by EPA based on a ratio of the FTP standards. The results are shown in Table
B-l.
-------
Appendix B: Methodology for Developing LEV SFTP Benefits
Table B-l: Worksheet for Developing LEV Benefits
FTP 50K Standard
Estimated "Running" FTP SOK Std
NMHC+NOx
EPA Tier 1
V/T1
0.65
0.42
T2
1.02
0.66
ARB LEV
V/T1
0.275
0.18
T2
0.50
0.33
CO
EPA Tier 1
V/T1 T2
3.4 4.4
2.2 2.9
ARB LEV
V/T1 T2
3.4 4.4
2.2 2.9
US06
4K Standard
Estimated SOK Standard
Increase, US06 vs. Run FTP (%)
Delta Increase (D), ARB vs. EPA (%)
EPA SFTP Benefit (%: NMHC/NOx)
EPA "Remainder" (100% - Benefit)
ARB "Remainder"(D applied to EPA Rem)
ARB Benefit (100% - ARB Remainder)
0.58
37
88/78
12/22
0.91
37
88/78
12/22
0.14
0.20
13
-66
4/7
96/93
0.26
0.35
8
-78
3/5
97/95
9.0 11.6
307 306
72 72
28 28
8.0 10.5
9.3 12.1
320 323
4 6
29 30
71 70
Air Conditioning
4K Standard
Estimated SOK Standard
Increase, US06 vs. Run FTP (%)
Delta Increase (D), ARB vs. EPA (%)
EPA SFTP Benefit (%: NOx Only)
EPA "Remainder" (100% - Benefit)
ARB "Remainder"(D applied to EPA Rem)
ARB Benefit (100% - ARB Remainder)
0.67
59
50
50
1.05
58
50
50
0.20
0.26
46
-21
39
61
0.27
0.37
14
-75
12
88
Methodology Not Applied
-------
Appendix C: Worksheets for Developing Modified Age Distributions
Table C-l: LDV
Column:
Vehicle
Age
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25+
A
MOBILESb
Annual
Mileage
(10K miles)
1.4390
1.4196
1.3428
1.2701
1.2016
1.1366
1.0752
1.0170
0.9620
0.9100
0.8608
0.8142
0.7702
0.7286
0.6892
0.6519
0.6167
0.5833
0.5518
0.5220
0.4938
0.4671
0.4418
0.4180
0.3953
B
ORNL
Survival
Rate
1.000
0.995
0.987
0.977
0.963
0.944
0.920
0.890
0.853
0.807
0.754
0.692
0.625
0.554
0.481
0.409
0.341
0.278
0.223
0.176
0.137
0.104
0.078
0.058
0.132
C
A*B
1.4390
1.4125
1.3253
1.2409
1.1571
1.0730
0.9892
0.9051
0.8206
0.7344
0.6490
0.5634
0.4814
0.4036
0.3315
0.2666
0.2103
0.1622
0.1231
0.0919
0.0677
0.0486
0.0345
0.0242
0.0522
D
Modified
Travel
Fraction
(C/£C)
0.099
0.097
0.091
0.085
0.079
0.073
0.068
0.062
0.056
0.050
0.044
0.039
0.033
0.028
0.023
0.018
0.014
0.011
0.008
0.006
0.005
0.003
0.002
0.002
0.004
E
MOBILESb
Travel
Fraction
0.068
0.107
0.107
0.100
0.097
0.088
0.079
0.055
0.046
0.044
0.041
0.042
0.035
0.026
0.016
0.012
0.008
0.008
0.006
0.004
0.003
0.002
0.002
0.001
0.004
F
Travel
Fraction
Ratio
(D/E)
n/a
0.901
0.850
0.852
0.820
0.833
0.854
1.136
1.220
1.131
1.078
0.916
0.951
1.071
1.433
1.539
1.742
1.325
1.450
1.573
1.633
1.489
1.396
1.377
0.944
G
MOBILESb
Age
Distribution
0.049
0.079
0.083
0.082
0.084
0.081
0.077
0.056
0.050
0.051
0.050
0.054
0.047
0.037
0.024
0.019
0.014
0.015
0.011
0.008
0.006
0.005
0.004
0.003
0.010
H
Modified
Age
Distribution
(F*G,
normalized)
0.049
0.071
0.070
0.069
0.068
0.067
0.065
0.063
0.061
0.057
0.054
0.049
0.044
0.039
0.034
0.029
0.024
0.020
0.016
0.013
0.010
0.007
0.006
0.004
0.009
-------
Appendix C: Worksheets for Developing Modified Age Distributions
Table C-2: MOBLDT1
Column:
Vehicle
Age
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25+
A
MOBILESb
Annual
Mileage
(10K miles)
1.5442
1.5209
1.4289
1.3425
1.2613
1.1850
1.1134
1.0461
0.9828
0.9234
0.8676
0.8151
0.7659
0.7195
0.6760
0.6352
0.5968
0.5607
0.5267
0.4949
0.4650
0.4369
0.4105
0.3857
0.3623
B
ORNL
Survival
Rate
1.000
0.998
0.994
0.988
0.979
0.967
0.948
0.924
0.892
0.852
0.806
0.755
0.702
0.649
0.597
0.548
0.502
0.459
0.419
0.383
0.349
0.319
0.290
0.265
1.942
C
A*B
1.5442
1.5179
1.4203
1.3264
1.2348
1.1459
1.0555
0.9666
0.8767
0.7867
0.6993
0.6154
0.5377
0.4670
0.4036
0.3481
0.2996
0.2574
0.2207
0.1895
0.1623
0.1392
0.1190
0.1022
0.7036
D
Modified
Travel
Fraction
(C/Eo
0.090
0.089
0.083
0.077
0.072
0.067
0.062
0.056
0.051
0.046
0.041
0.036
0.031
0.027
0.024
0.020
0.017
0.015
0.013
0.011
0.009
0.008
0.007
0.006
0.041
E
MOBILESb
Travel
Fraction
0.092
0.120
0.113
0.106
0.100
0.077
0.062
0.043
0.033
0.027
0.025
0.041
0.034
0.031
0.023
0.017
0.010
0.012
0.008
0.007
0.004
0.003
0.003
0.002
0.009
F
Travel
Fraction
Ratio
(D/E)
0.984
0.736
0.733
0.729
. 0.722
0.868
0.996
1.301
1.535
1.703
1.665
0.883
0.926
0.874
1.028
1.213
1.830
1.293
1.527
1.695
2.403
2.467
2.246
3.284
4.813
G
MOBILESb
Age
Distribution
0.063
0.084
0.084
0.084
0.084
0.069
0.059
0.044
0.036
0.031
0.030
0.053
0.047
0.046
0.036
0.028
0.017
0.022
0.017
0.014
0.009
0.008
0.008
0.005
0.025
H
Modified
Age
Distribution
(F*G,
normalized^
0.055
0.054
0.054
0.053
0.053
0.052
0.051
0.050
0.048
0.046
0.043
0.041
0.038
0.035
0.032
0.030
0.027
0.025
0.023
0.021
0.019
0.017
0.016
0.014
0.105
-------
Appendix C: Worksheets for Developing Modified Age Distributions
Table C-3: MOBLDT2
Column:
Vehicle
Age
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25+
A
MOBILESb
Annual
Mileage
(10K miles)
1.4779
1.4649
1.4134
1.3637
1.3159
1.2697
1.2250
1.1819
1.1404
1.1004
1.0617
1.0244
0.9884
0.9537
0.9202
0.8878
0.8566
0.8266
0.7975
0.7695
0.7424
0.7164
0.6912
0.6669
0.6435
B
ORNL
Survival
Rate
1.000
0.998
0.994
0.988
0.979
0.967
0.948
0.924
0.892
0.852
0.806
0.755
0.702
0.649
0.597
0.548
0.502
0.459
0.419
0.383
0.349
0.319
0.290
0.265
1.942
C
A*B
1.4779
1.4620
1.4049
1.3473
1.2883
1.2278
1.1613
1.0921
1.0172
0.9375
0.8557
0.7734
0.6939
0.6190
0.5494
0.4865
0.4300
0.3794
0.3342
0.2947
0.2591
0.2282
0.2004
0.1767
1.2497
D
Modified
Travel
Fraction
(C/£C)
0.074
0.073
0.070
0.068
0.065
0.062
0.058
0.055
0.051
0.047
0.043
0.039
0.035
0.031
0.028
0.024
0.022
0.019
0.017
0.015
0.013
0.011
0.010
0.009
0.063
E
MOBILESb
Travel
Fraction
0.070
0.092
0.089
0.086
0.083
0.058
0.053
0.035
0.054
0.030
0.026
0.071
0.072
0.041
0.031
0.023
0.013
0.017
0.013
0.010
0.006
0.005
0.005
0.003
0.015
F
Travel
Fraction
Ratio
(D/E)
1.065
0.797
0.794
0.789
0.782
1.069
1.090
1.562
0.950
1.580
1.655
0.543
0.480
0.761
0.880
1.050
1.603
1.147
1.338
1.468
2.229
2.289
1.853
2.539
4.294
G
MOBILESb
Age
Distribution
0.054
0.072
0.072
0.072
0.072
0.052
0.050
0.034
0.054
0.031
0.028
0.080
0.084
0.049
0.039
0.030
0.018
0.023
0.018
0.015
0.009
0.008
0.009
0.006
0.026
H
Modified
Age
Distribution
(F*G,
normalized^
0.021
0.056
0.056
0.055
0.055
0.054
0.053
0.052
0.050
0.048
0.045
0.042
0.039
0.036
0.033
0.031
0.028
0.026
0.023
0.021
0.019
0.018
0.016
0.015
0.108
-------
Appendix D: Results
Table D-l: Northeast (OTR NLEV, I/M, RFC)
Pollutant
NOx
NMHC
CO
Model
Modified
MOBILESb
MOBILESb
Modified
MOBILESb
MOBILESb
Modified
MOBILESb
MOBILESb
Calender
Year
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
Emission Rate (Grams/Mile)
LDGV ILDGTI |LDGX2 1 HDGV | LDDV
1.27 1.56 2.16 4.64 1.32
0.84 1.22 1.60 3.95 1.05
0.72 1.18 1.56 3.55 1.00
0.57 0.95 1.20 3.15 1.00
0.44 0.82 1.01 2.54 1.01
0.40 0.71 0.75 2.12 1.02
0.95 1.09 1.61 4.78 1.23
0.60 0.75 1.37 4.17 1.03
0.49 0.64 1.32 3.78 0.99
0.38 0.54 1.25 3.39 0.99
0.30 0.43 1.22 2.78 1.00
0.27 0.40 1.21 2.37 1.00
1.02 1.70 2.27 4.40 0.55
0.56 0.87 1.20 • 3.22 0.42
0.44 0.70 1.00 2.95 0.41
0.32 0.47 0.69 2.33 0.41
0.23 0.35 0.57 2.01 0.43
0.20 0.27 0.47 1.71 0.43
0.89 1.16 1.64 4.45 0.50
0.48 0.65 1.15 3.30 0.41
0.39 0.52 1.04 3.03 0.40
0.29 0.39 0.90 2.40 0.40
0.22 0.28 0.82 2.09 0.41
0.21 0.24 0.76 1.79 0.42
11.90 15.91 24.18 40.68 1.30
6.96 8.48 14.24 21.65 1.14
5.72 7.63 13.39 19.37 1.12
4.24 5.17 9.74 12.52 1.13
3.02 3.72 7.88 12.12 1.15
2.59 2.56 5.25 12.12 1.15
5.80 8.02 12.54 41.39 1.24
3.47 5.10 10.61 22.62 1.13
3.02 4.47 10.71 20.39 1.11
2.71 3.80 10.68 13.59 1.12
2.57 3.38 10.72 13.20 1.13
2.52 3.22 10.83 13.20 1.14
LDDT
1.51
1.32
1.21
1.15
1.15
1.17
1.34
1.15
1.13
1.12
1.13
1.14
0.78
0.67
0.61
0.58
0.59
0.62
0.67
0.56
0.55
0.55
0.56
0.58
1.48
1.35
1.30
1.27
1.28
1.30
1.36
1.25
1.24
1.24
1.25
1.27
HDDV
10.34
7.61
6.56
5.32
4.19
3.67
10.34
7.61
6.56
5.32
4.19
3.67
1.80
1.52
1.27
0.97
0.66
0.49
1.80
1.52
1.27
0.97
0.66
0.49
9.08
8.87
8.83
8.81
8.80
8.80
9.08
8.87
8.83
8.81
8.80
8.80
MC
0.82
0.82
0.82
0.82
0.82
0.82
0.82
0.82
0.82
0.82
0.82
0.82
4.51
4.51
4.51
4.51
4.51
4.51
4.51
4.51
4.51
4.51
4.51
4.51
17.50
17.50
17.50
17.50
17.50
17.50
17.50
17.50
17.50
17.50
17.50
17.50
All
2.26
1.68
1.52
1.23
1.02
0.87
1.80
1.34
1.17
0.98
0.82
0.75
1.53
0.92
0.76
0.56
0.44
0.36
1.20
0.76
0.64
0.50
0.41
0.36
15.12
9.07
8.12
6.03
4.81
3.85
8.20
5.49
5.05
4.53
4.38
4.34
-------
Appendix D: Results
Table D-2: Chicago (Non-OTR NLEV, I/M, RFC)
Pollutant
NOx
NMHC
CO
Model
Modified
MOBILESb
MOBILESb
Modified
MOBILESb
MOBILESb
Modified
MOBILESb
MOBILESb
Calender
Year
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
Emission Rate (Grams/Mile)
LDGV ILDGTI |LDGT2 1 HDGV | LDDV | LDDT | HDDV | MC
1.28 1.54 2.16 4.64 1.32 1.51 10.34 0.82
0.85 1.20 1.60 3.95 1.05 1.32 7.61 0.82
0.73 1.17 1.56 3.55 1.00 1.21 6.56 0.82
0.58 0.94 1.20 3.15 1.00 1.15 5.32 0.82
0.45 0.82 1.01 2.54 1.01 1.15 4.19 0.82
0.40 0.71 0.75 2.12 1.02 1.17 3.67 0.82
0.96 1.11 1.61 4.78 1.23 1.34 10.34 0.82
0.61 0.77 1.37 4.17 1.03 1.15 7.61 0.82
0.50 0.66 1.32 3.78 0.99 1.13 6.56 0.82
0.39 0.55 1.25 3.39 0.99 1.12 5.32 0.82
0.30 0.44 1.22 2.78 1.00 1.13 4.19 0.82
0.27 0.40 1.21 2.37 1.00 1.14 3.67 0.82
1.05 1.72 2.27 4.40 0.55 0.78 1.80 4.51
0.58 0.90 1.20 3.22 0.42 0.67 1.52 4.51
0.46 0.72 1.00 2.95 0.41 0.61 1.27 4.51
0.33 0.48 0.69 2.33 0.41 0.58 0.97 4.51
0.24 0.36 0.57 2.01 0.43 0.59 0.66 4.51
0.21 0.28 0.47 1.71 0.43 0.62 0.49 4.51
0.91 1.18 1.64 4.45 0.50 0.67 1.80 4.51
0.51 0.67 1.15 3.30 0.41 0.56 1.52 4.51
0.40 0.54 1.04 3.03 0.40 0.55 1.27 4.51
0.30 0.40 0.90 2.40 0.40 0.55 0.97 4.51
0.23 0.29 0.82 2.09 0.41 0.56 0.66 4.51
0.21 0.24 0.76 1.79 0.42 0.58 0.49 4.51
12.03 16.04 24.18 40.68 1.30 1.48 9.08 17.50
7.01 8.61 14.24 21.65 1.14 1.35 8.87 17.50
5.75 7.74 13.39 19.37 1.12 1.30 8.83 17.50
4.24 5.26 9.74 12.52 1.13 1.27 8.81 17.50
3.02 3.76 7.88 12.12 1.15 1.28 8.80 17.50
2.59 2.59 5.25 12.12 1.15 1.30 8.80 17.50
5.83 8.00 12.54 41.39 1.24 1.36 9.08 17.50
3.46 5.07 10.61 22.62 1.13 1.25 8.87 17.50
2.99 4.45 10.71 20.39 1.11 1.24 8.83 17.50
2.68 3.77 10.68 13.59 1.12 1.24 8.81 17.50
2.55 3.37 10.72 13.20 1.13 1.25 8.80 17.50
2.51 3.22 10.83 13.20 1.14 1.27 8.80 17.50
All
2.26
1.68
1.52
1.24
1.02
0.87
1.81
1.35
1.18
0.99
0.82
0.75
1.55
0.93
0.78
0.57
0.44
0.36
1.22
0.78
0.66
0.52
0.41
0.36
15.21
9.13
8.17
6.06
4.82
3.86
8.21
5.48
5.03
4.51
4.37
4.34
-------
Appendix D: Results
Table D-3: Atlanta (Non-OTR NLEV, I/M, No RFC)
IPollutant
NOx
NMHC
CO
Model
Modified
MOBILESb
MOBILESb
Modified
MOBILESb
MOBILESb
Modified
MOBILESb
MOBILESb
Calender
Year
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
Emission Rate (Grams/Mile)
LDGV
1.37
0.94
0.82
0.66
0.54
0.49
1.03
0.66
0.54
0.42
0.32
0.29
1.55
0.89
0.72
0.54
0.41
0.36
1.36
0.78
0.63
0.48
0.38
0.35
15.27
8.85
7.23
5.33
3.78
3.23
7.21
4.20
3.61
3.24
3.15
3.14
LDGT1 |LDGT2
1.62 2.25
1.31 1.68
1.28 1.64
1.07 1.27
0.95 1.08
0.84 0.80
1.17 1.69
0.82 1.45
0.70 1.40
0.59 1.33
0.47 1.29
0.43 1.29
2.29 2.97
1.25 1.65
1.01 1.36
0.69 0.94
0.53 0.78
0.42 0.65
1.57 2.15
0.91 1.53
0.74 1.39
0.57 1.20
0.42 1.09
0.36 1.02
20.31 30.24
11.08 18.46
9.97 17.35
6.62 12.32
4.72 9.88
3.19 6.40
10.01 15.81
6.27 13.41
5.47 13.53
4.59 13.45
4.15 13.50
4.00 13.65
HDGV
4.69
4.01
3.61
3.20
2.58
2.16
4.83
4.22
3.84
3.45
2.83
2.41
6.30
4.79
4.43
3.60
3.16
2.78
6.36
4.87
4.52
3.69
3.25
2.87
49.66
27.60
24.99
17.11
16.63
16.62
50.62
28.93
26.40
18.58
18.11
18.10
LDDV
1.32
1.05
1.00
1.00
1.01
1.02
1.23
1.03
0.99
0.99
1.00
1.00
0.55
0.42
0.41
0.41
0.43
0.43
0.50
0.41
0.40
0.40
0.41
0.42
1.30
1.14
1.12
1.13
1.15
1.15
1.24
1.13
1.11
1.12
1.13
1.14
LDDT | HDDV | MC
1.51 10.34 0.82
1.32 7.61 0.82
1.21 6.56 . 0.82
1.15 5.32 0.82
1.15 4.19 0.82
1.17 3.67 0.82
1.34 10.34 0.82
1.15 7.61 0.82
1.13 6.56 0.82
1.12 5.32 0.82
1.13 4.19 0.82
1.14 3.67 0.82
0.78 1.80 5.91
0.67 1.52 5.91
0.61 1.27 5.91
0.58 0.97 5.91
0.59 0.66 5.91
0.62 0.49 5.91
0.67 1.80 5.91
0.56 1.52 5.91
0.55 1.27 5.91
0.55 0.97 5.91
0.56 0.66 5.91
0.58 0.49 5.91
1.48 9.08 20.52
1.35 8.87 20.52
1.30 8.83 20.52
1.27 8.81 20.52
1.28 8.80 20.52
1.30 8.80 20.52
1.36 9.08 20.52
1.25 8.87 20.52
1.24 8.83 20.52
1.24 8.81 20.52
1.25 8.80 20.52
1.27 8.80 20.52
All
2.34
1.76
1.61
1.32
1.11
0.96
1.87
1.40
1.22
1.03
0.85
0.77
2.10
1.30
1.08
0.81
0.64
0.54
1.68
1.08
0.92
0.73
0.60
0.53
18.98
11.47
10.25
7.49
5.91
4.65
10.03
6.61
6.05
5.42
5.30
5.29
-------
Appendix D: Results
Table D-4: Attainment (Non-OTR NLEV, No I/M, No RFC)
Pollutant
NOx
NMHC
CO
Model
Modified
MOBILESb
MOBILESb
Modified
MOBILESb
MOBILESb
Modified
MOBILESb
MOBILESb
Calender
Year
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
2000
2005
2007
2010
2015
2020
Emission Rate (Grams/Mile)
LDGV ILDGTI |LDGT2| HDGV | LDDV | LDDT | HDDV | MC
1.78 2.25 3.01 4.83 1.32 1.51 10.34 0.82
1.19 1.77 2.26 4.22 1.05 1.32 7.61 0.82
1.02 1.69 2.14 3.84 1.00 1.21 6.56 0.82
0.83 1.52 1.85 3.45 1.00 1.15 5.32 0.82
0.65 1.27 1.42 2.83 1.01 1.15 4.19 0.82
0.59 1.13 1.11 2.41 1.02 1.17 3.67 0.82
1.43 1.64 2.24 4.83 1.23 1.34 10.34 0.82
1.29 1.48 2.14 4.22 1.03 1.15 7.61 0.82
1.25 1.44 2.12 3.84 0.99 1.13 6.56 0.82
1.22 1.41 2.11 3.45 0.99 1.12 5.32 0.82
1.19 1.37 2.06 2.83 1.00 1.13 4.19 0.82
1.19 1.36 2.05 2.41 1.00 1.14 3.67 0.82
2.30 3.19 4.09 6.36 0.55 0.78 1.80 5.91
1.52 2.05 2.69 4.87 0.42 0.67 1.52 5.91
1.30 1.87 2.52 4.52 0.41 0.61 1.27 5.91
1.05 1.52 2.07 3.69 0.41 0.58 0.97 5.91
0.84 1.25 1.77 3.25 0.43 0.59 0.66 5.91
0.77 1.10 1.60 2.87 0.43 0.62 0.49 5.91
2.28 2.66 3.52 6.36 0.50 0.67 1.80 5.91
1.89 2.20 3.11 4.87 0.41 0.56 1.52 5.91
1.79 2.11 3.02 4.52 0.40 0.55 1.27 5.91
1.68 2.00 2.87 3.69 0.40 0.55 0.97 5.91
1.60 1.88 2.74 3.25 0.41 0.56 0.66 5.91
1.58 1.84 2.66 2.87 0.42 0.58 0.49 5.91
24.76 29.81 41.58 50.62 1.30 1.48 9.08 20.52
14.68 17.66 26.14 28.93 1.14 1.35 8.87 20.52
12.04 16.88 25.96 26.40 1.12 1.30 8.83 20.52
9.05 12.36 19.43 18.58 1.13 1.27 8.81 20.52
6.59 8.78 14.19 18.11 1.15 1.28 8.80 20.52
5.78 6.48 11.05 18.10 1.15 1.30 8.80 20.52
15.61 19.25 26.63 50.62 1.24 1.36 9.08 20.52
14.19 16.97 23.77 28.93 1.13 1.25 8.87 20.52
13.90 16.78 23.71 26.40 1.11 1.24 8.83 20.52
13.65 16.68 23.79 18.58 1.12 1.24 8.81 20.52
13.43 16.47 23.57 18.11 1.13 1.25 8.80 20.52
13.39 16.40 23.53 18.10 1.14 1.27 8.80 20.52
All
2.80
2.10
1.90
1.63
1.32
1.15
2.25
1.96
1.85
1.73
1.61
1.55
2.85
1.96
1.76
1.45
1.21
1.08
2.57
2.14
2.02
1.87
1.75
1.69
27.62
17.13
15.72
11.97
9.08
7.53
17.89
15.61
15.32
14.90
14.68
14.63
------- |