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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION III

1650 Arch Street

Philadelphia, Pennsylvania 19103

DATE: February 26, 2014

SUBJECT: Technical Support Document for the Update of the Motor Vehicle Emissions 

Budgets for the Reading 1997 Eight-Hour Ozone National Ambient Air Quality

Standard Maintenance Area 

FROM: Asrah Khadr, Environmental Engineer, EIT /s/

Office of Air Program Planning 

TO: File

THRU: Cristina Fernandez, Associate Director /s/ 

Office of Air Program Planning

A. BACKGROUND: 

On July 22, 2013, the Pennsylvania Department of Environmental Protection (PADEP) 

submitted a revision to the Commonwealth of Pennsylvania’s (Pennsylvania) State 

Implementation Plan (SIP). The SIP revision consists of updated Motor Vehicle Emissions 

Budgets (MVEBs) for nitrogen oxides (NOx) for the 1997 Eight-Hour Ozone National Ambient 

Air Quality Standard (NAAQS). The SIP revision also includes updated point and area source 

inventories for NOx. The updated budgets were calculated using the Environmental Protection 

Agency’s (EPA) Motor Vehicle Emission Simulator model (MOVES2010a). The intention of 

the revised SIP is to replace the approved MOBILE6.2-based MVEBs with budgets based on 

MOVES2010a and to ensure that the SIP revision still provides for attainment of the 1997 EightHour Ozone NAAQS. 

On July 18, 1997 (62 FR 38856), EPA established the 1997 Eight-Hour Ozone NAAQS. On 

April 30, 2004 (69 FR 23858), Berks County was designated as nonattainment for the 1997 

Eight-Hour Ozone NAAQS. On January 25, 2007, PADEP submitted a SIP revision which 

consists of a maintenance plan, a 2002 base year inventory and MVEBs for transportation 

conformity purposes. On August 24, 2007 (72 FR 48559), EPA approved the SIP revision as 

well as the redesignation request made by PADEP. Berks County was redesignated as a 

maintenance area. 

The MVEBs are a mobile source inventory to which an area’s transportation improvement 

program (TIP) and long range transportation plan must conform. Conformity to MVEBs in a SIP 

means that transportation activities will not produce new air quality violations, worsen existing 

violations, or delay timely attainment of the NAAQS or any required interim milestones. This 
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July 22, 2013 SIP revision submittal provides updated MVEBs for NOx. The budgets were 

developed utilizing MOVES2010a. On March 2, 2010 (75 FR 9411), EPA published a notice of 

availability for the MOVES2010 model for use in SIP submissions and started a two year grace 

period for the use of MOVES2010 for transportation conformity purposes. The two year grace 

period was scheduled to end on March 2, 2012. On February 27, 2012 (77 FR 11394), EPA 

published a final rule extending the grace period another year to March 2, 2013 to ensure 

adequate time for affected parties to adopt the model. On September 8, 2010, EPA released 

MOVES2010a, which is a minor update to MOVES2010. Pennsylvania utilized MOVES2010a 

in its November 19, 2012 SIP revision. MOVES2010a was used in order to ensure that the 

nonattainment area can demonstrate transportation conformity using MOVES2010a once the 3-

year conformity grace period expires. Pennsylvania updated their SIP-approved MVEBs with 

the use of MOVES2010a. The budgets were previously developed with the use of the Highway

Mobile Source Emission Factor Model (MOBILE6.2). 

MOBILE6.2 is a motor vehicle emissions factor model that was utilized for SIPs and 

transportation conformity. MOBILE6.2 was made available for use in SIPs and transportation 

conformity purposes on May 19, 2004 (69 FR 28830). MOBILE6.2 was merely an update to 

MOBILE6 that added the ability for the program to estimate direct exhaust and brake and tire 

wear particulate matter emission factors as well as exhaust emission factors for particulate matter 

precursors. 

MOVES2010 improves upon MOBILE6.2 in many aspects. MOVES2010 utilizes a plethora of 

vehicle data that has been made available since the release of MOBILE6.2; this vehicle data 

includes emissions data for different kinds of vehicles. The new data has allowed EPA to better 

understand on-road mobile source emissions and their contribution to emissions inventories as 

well as how effective different control strategies are. The MOVES2010 model offers more 

flexibility because the program has a database design that allows easier organization of input and 

output files and data. The database design of the MOVES2010 model allows much easier update 

of input data upon the release of new data. MOVES2010 also accounts for temperature and 

speed variations and allows the model to run at a higher resolution which allows for the input of 

more activity data. 

Under Section 176(c) of the Clean Air Act (CAA), any federal action is required to conform to 

the applicable SIP. A part of this requirement for conformity is transportation conformity. 

Transportation conformity requires that any federally funded transportation plan, program or 

project conform to the applicable SIP for the transportation-related criteria pollutants (ozone, 

carbon monoxide, PM2.5, PM10, and nitrogen dioxide). The transportation conformity rules can 

be found at 40 CFR 93, Subpart A. One of the requirements found under 40 CFR 93, Subpart A 

is that any transportation plan, TIP or project not in a conforming TIP must conform to the 

MVEBs in the applicable SIP. In order for the MVEBs in a SIP to be used to determine 

conformity of a transportation plan, TIP or project, the MVEBs must be either approved or 

deemed adequate. In this case, the budgets must be approved because this SIP revision is 

revising already approved budgets. However, in reviewing such a submitted SIP it remains 

useful to apply the criteria used to make an adequacy finding. The requirements for adequacy

are set forth in 40 CFR 93.118(e)(4)(i)-(vi). The criteria for adequacy and how they are met by

the Pennsylvania submittal are found below in Table 1. Adequacy Criteria.
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Table 1. Adequacy Criteria

Criterion Submittal

(i) The submitted control strategy implementation plan 

revision or maintenance plan was endorsed by the 

Governor (or his or her designee) and was subject to a 

State public hearing;

 Letter addressed to Shawn M. Garvin, 

Regional Administrator, EPA Region 

III from E. Christopher Abruzzo, 

Acting Secretary, Pennsylvania DEP

 Public hearing documents were 

submitted 

(ii) Before the control strategy implementation plan or 

maintenance plan was submitted to EPA, consultation 

among federal, State, and local agencies occurred; full 

implementation plan documentation was provided to 

EPA; and EPA's stated concerns, if any, were addressed;

 N/A, this revision does not 

accompany a control strategy 

implementation plan or maintenance 

plan

(iii) The motor vehicle emissions budget(s) is clearly 

identified and precisely quantified;

 Appendix C-2 of the submittal 

provides detailed emission summary 

tables

(iv) The motor vehicle emissions budget(s), when 

considered together with all other emissions sources, is 

consistent with applicable requirements for reasonable 

further progress, attainment, or maintenance (whichever 

is relevant to the given implementation plan 

submission);

 Maintenance plan for Berks County 

was already approved on July 6, 2007 

(72 FR 36889), no changes to 

nonroad source emissions, point and 

area source emissions were updated

 Berks County continues to attain the 

1997 Ozone NAAQS as shown by the 

design value obtained from 2010-

2012 data

 Update of point and area source 

emissions shows less emissions than 

those predicted in the maintenance 

plan

(v) The motor vehicle emissions budget(s) is consistent 

with and clearly related to the emissions inventory and 

the control measures in the submitted control strategy 

implementation plan revision or maintenance plan; and

 The SIP revision shows no change in 

any control measures in the 

previously submitted maintenance 

plan.

(vi) Revisions to previously submitted control strategy 

implementation plans or maintenance plans explain and 

document any changes to previously submitted budgets 

and control measures; impacts on point and area source 

emissions; any changes to established safety margins 

(see § 93.101 for definition); and reasons for the changes 

(including the basis for any changes related to emission 

factors or estimates of vehicle miles traveled).

 Changes in MVEBs are clearly 

documented and explained in the 

submittal. The higher emissions are 

due to the use of MOVES2010a 

which is a more accurate emissions 

model and is based on more recent 

data on vehicle emissions than 

MOBILE6.2. Update of point source 

emissions and addition of small safety 

margin are well explained. 
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B. STATE SUBMITTAL:

On January 22, 2013, PADEP submitted a SIP revision which included an update to the MVEBs 

for NOx and volatile organic compounds (VOCs) for the years 2009 (interim year) and 2018 

(maintenance year). The updated MVEBs were produced using the MOVES2010a model. The 

MVEBs were developed with guidance from the following EPA guidance documents: Policy 

Guidance on the Use of MOVES2010 for SIP Development, Transportation Conformity, and 

Other Purposes and Technical Guidance on the Use of MOVES2010 for Emission Inventory 

Preparation in State Implementation Plans and Transportation Conformity. The submittal also 

included an update tro the point and area source emissions inventories. 

I. Methodology for Developing Data for Use in MOVES2010a

PADEP utilized MOVES2010a to provide emissions rates for emissions of NOx and VOCs. 

PPSUITE is a program that was utilized for the processing of highway information and to 

provide input files that are usable by the MOVES2010a model. PPSUITE was run utilizing 

CENTRAL; CENTRAL is a program that provides a process for the proper function of PPSUITE 

and MOVES2010a. The MVEBs were developed for NOx and VOCs since they are the two 

biggest contributors to the formation of ozone. 

In PPSUITE, the Pennsylvania Department of Transportation (PennDOT) Roadway Management 

System (RMS) data among other data was utilized to produce vehicle miles traveled (VMT) 

estimates. The VMT produced via PPSUITE was then imported into the county data manager 

(CDM) in MOVES2010a. Since VOCs and NOx emissions differ with respect to travel speed, 

travel speed is utilized as an input in MOVES2010a. To develop an array of travel speeds, 

PPSUITE was utilized to develop vehicle hours of travel (VHT) by speed bin file which allows 

for the distribution of speeds across links into MOVES2010a speed bins. The travel speed 

calculations were completed with guidance from Technical Guidance on the Use of MOVES2010 

for Emission Inventory Preparation in State Implementation Plans and Transportation 

Conformity. 

Road type distribution was another traffic input for MOVES2010a. Road type distribution was 

developed with the use of PPSUITE. The five different road types utilized by MOVES2010a are 

off network, rural restricted access, rural unrestricted access, urban restricted access and urban 

unrestricted access. In addition, ramps are not included in road type distribution so it is assumed 

that 8% of the roadway VHT is ramp VHT. This traffic input assumption is consistent with 

EPA’s technical guidance. 

Before RMS data is utilized by PPSUITE to develop various traffic inputs, several adjustments 

must be made. The RMS VMT is adjusted to meet the Highway Performance Monitoring 

System (HPMS) VMT totals. HPMS VMT utilizes snapshots of RMS VMT to satisfy reporting 

requirements established by the Federal Highway Administration (FHWA). To make this 

adjustment, adjustment factors were calculated and utilized. 

Adjustments to average annual daily traffic (AADT) were completed because calculations for 
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ozone precursors are based on a summer weekday, since that is when ozone formation tends to 

be the greatest. The RMS AADT volumes are adjusted by the use of a seasonal factor that was 

developed by PennDOT’s Bureau of Planning and Research (BPR) to produce July traffic 

volumes. The RMS data was also adjusted for differences in hourly traffic volumes. The 24-

hour pattern data provided to PPSUITE allowed PPSUITE to provide roadway segment volumes 

by the hour. The 24-hour pattern data was obtained from PennDOT’s PBR.

Traffic volume forecasts had to be applied to estimate future emissions from vehicles. The 

growth rates utilized for these forecasts are the PennDOT PBR growth rate forecasting system, 

the regional travel model and any applicable Marcellus Shale related activity growth. 

Additionally, county specific growth rates were utilized from a 2005 PennDOT report titled 

Statistical Evaluation of Projected Traffic Growth, Traffic Growth Forecasting System: Final 

Report, March 14, 2005. 

MOVES2010a utilizes 13 vehicle source types. Since HPMS utilizes different categories for 

vehicle types, the RMS traffic volumes were disaggregated to the 13 vehicle source types which 

were then combined into the 6 HPMS vehicle classes. Vehicle type data input into PPSUITE is 

used to divide the roadway segment volumes with respect to the MOVES2010a source types. 

The source types are split into percentages among the 24-hours of the day. The vehicle source 

type percentages are then utilized to adjust vehicle speeds in response to trucks. 

Vehicle population is also another important input for MOVES2010a. Vehicle population is 

input into MOVES2010a with respect to the 13 vehicle source types utilized by the model. 

County level vehicle registration data is utilized for light duty vehicles and school buses. Transit 

bus data is obtained from PennDOT’s National Transit Database (NTD); it is utilized to estimate 

county level transit bus counts. Heavy duty vehicle population data is estimated by utilizing 

source type VMT and vehicle source and pattern data are utilized. Vehicle age is input into the 

model as well. The vehicle age is input into the model as a percentage of vehicles of the fleet 

between ages 0 and 31. 

Outside of vehicle and roadway data, environmental variables are utilized as inputs since 

evaporative emissions are dependent on the surrounding temperatures. The environmental 

variables used included hourly temperatures and humidity values. The temperatures were 

retrieved by Weather Bank, Inc. Humidity values were produced according to EPA’s technical 

guidance. Minimum and maximum monthly temperatures were converted to hourly

temperatures using EPA converters in the MOVES2010a model. 

Fuel parameters were also input since different fuels produce different emissions. The 

MOVES2010a default fuel formulation and supply data was utilized and updated with local

volumetric fuel property data. Gasohol market penetration and RVP values were updated at the 

county level. Other fuel parameters were obtained through the MOVES2010a default data.

Refueling emissions were not included as an input because Pennsylvania provides the refueling 

emissions in its area source inventory; hence it is not required for the production of MVEBs. 

Additionally, MOVES2010a also includes input parameters for inspection and maintenance 

(I/M) programs. The inputs for the I/M program include: program start year, stringency level, 
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first and last model years subject to the program, waiver rates, compliance rates, program type 

and effectiveness, frequency of inspection, vehicle type coverage and test type. The defaults for 

an I/M program in MOVES2010a were modified to accurately represent the I/M program for 

Berks County. 

II. Running MOVES2010a

As stated in Section I, the data utilized to run MOVES2010a is a mixture of local and national 

data. Local data is utilized for all inputs that have significant impact on the emissions rates that 

are calculated by MOVES2010a. The local data utilized as inputs for MOVES2010a is 

categorized into five categories which include: traffic data, vehicle descriptions, fuel parameters, 

I/M programs, and environmental variables. The inputs for traffic data include vehicle type 

VMT, vehicle population, VMT fractions, road type distribution, and ramp fractions. The inputs 

for vehicle descriptions include vehicle type mix, vehicle age distribution, average speeds and 

hourly distributions of different vehicles. The inputs for fuel parameters include RVP, sulfur 

level and ethanol volume. The inputs for I/M programs include start and model years, the 

frequency of tests, test standards, source types, stringency of tests, the waiver rate, and 

compliance rates. The inputs for environmental variables include hourly temperatures and 

humidity. 

MOVES2010a inputs that were prepared by PPSUITE included vehicle type VMT, vehicle 

population, VMT fractions, average speed distributions, road type distribution and ramp 

fractions. These files were input into the MOVES2010a county data importer. Additional nonPPSUITE inputs included fuel and vehicle ages, as well as temperatures and I/M programs. The 

county data importer was run in batch mode. Running the county data importer converts input 

files into a MYSQL format which is accepted by MOVES2010a. Afterwards, a MOVES run 

specification file (.mrs) was created. This file includes options and different data locations for 

the execution of the model. MOVES2010a can be executed to provide an emissions rate or an 

emissions inventory. In this submittal, MOVES2010a was executed to provide an emissions 

inventory. The emissions estimates of NOx produced for the years 2004, 2009 and 2018 by

MOVES2010a are provided in Table 2. Summary of Motor Vehicle Emissions. The emissions 

estimates are provided in tons per day (tpd); also provided in Table 2 is the comparison between 

the emissions produced by MOBILE6.2 and MOVES2010a. No new emissions estimates were 

produced for VOCs therefore their inclusion into the MOVES estimates portion in the table 

below is not applicable (N/A). After reviewing this submittal, EPA concurs with Pennsylvania 

that even though the emissions results produced by MOVES2010a are greater than those 

previously calculated using MOBILE6.2. EPA’s review of the SIP revision indicates these 

higher emissions result from improvements in the MOVES model rather than from unanticipated 

growth or changes in control measures. The MOVES results are more accurate estimates of the 

emissions that actually occurred in 2002 and 2009, rather than an indication that emissions are 

increasing. More importantly, Berks County attained the 1997 Eight-Hour Ozone NAAQS and 

was redesignated to a maintenance area on July 6, 2007 (72 FR 36889). Berks County continues 

to attain the 1997 Eight-Hour Ozone NAAQS as shown by its 2010-2012 design values. The 

two air quality monitors in Berks County are providing design values of 75 parts per billion 

(ppb) and 79 ppb, which are below the 1997 Eight-Hour Ozone NAAQS of 0.08 ppm. Also, the 
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preliminary 2011-2013 design value for the Berks County air quality monitor with the highest 

design value is 73 ppb which is below the 1997 Eight-Hour Ozone NAAQS. Therefore, EPA 

finds this update to the MVEBs does not interfere with Berks County’s ability to maintain its 

attainment of the1997 Eight-Hour Ozone NAAQS.

Table 2. Summary of Motor Vehicle Emissions in TPD

Model MOBILE6.2 MOVES2010a

Year 2004 2009 2018 2004 2009 2018

VOCs 17.0 12.1 6.5 N/A N/A N/A

NOx 29.8 20.7 8.4 34.4 27.0 12.9

III. Review of MOVES Modeling 

To run the MOVES2010a model, a run specification (hereafter referred to as “RunSpec”) must be 

created so the appropriate parameters are selected for the modeling run. The RunSpecs were 

reviewed against the following EPA document: Technical Guidance on the use of MOVES2010 

for Emission Inventory Preparation in State Implementation Plans and Transportation Conformity. 

This guidance document provides guidance on the use of the MOVES model to develop 

inventories for SIPs as well as analysis of emissions for transportation conformity determinations. 

MVEBs were submitted for the years 2009 and 2018 for the 1997 Ozone NAAQS which are 

consistent with the rest of the emissions inventory in the maintenance plan. The submitted 

RunSpecs, input files and output files were reviewed and found to have followed the applicable 

EPA guidance provided in the Technical Guidance on the use of MOVES2010 for Emission 

Inventory Preparation in State Implementation Plans and Transportation Conformity. Table 3. 

RunSpec Reviews for the 1997 Eight-Hour Ozone NAAQS for Years 2009 and 2018 for Berks 

County, presents the RunSpec parameters that were reviewed and each parameter’s respective 

component in the submittal.

Table 3. RunSpec Reviews for the 1997 Ozone NAAQS for Years 2009 and 2018 for Berks 

County

Domain/Scale County scale was selected. Selection of county scale is acceptable 

for this air quality analysis. 

Calculation Type Inventory was selected which is acceptable for this analysis.

Time Aggregation Level Hourly time aggregation was selected. Selection of hourly time 

aggregation level is acceptable for this analysis.

Calendar Year Of 

Evaluation

The appropriate calendar year was selected for each RunSpec; each 

RunSpec has 2009 or 2018 as the selected calendar year. 

MOVES2010b can model years 1990 and 1999-2050. 

Month of Evaluation July was selected to be the month of evaluation. This is acceptable 

for ozone precursor analysis. 

Type of Day of 

Evaluation

Weekdays were selected, which is appropriate for the evaluation of 

pollutant emissions related to ozone. 
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Hours of Evaluation Starting and ending hours create a whole day (from 0-24 hours).

Geographic Bounds Berks County was selected for each RunSpec. 

Vehicles/Equipment: OnRoad Vehicle Equipment Appropriate combinations of fuels and source use types were made.

Road Type Selection included all necessary road types. 

Pollutants and Processes NOx, total gaseous hydrocarbons, non-methane hydrocarbons, and 

VOCs were selected. 

On-Road Retrofits N/A

ROP N/A

Output Database/Unit 

Selection

Mass units selected to be grams; energy units selected to be million 

British Thermal Unit (BTU); distance units selected to be miles. 

Output Emission Detail in 

Emission Rate 

Calculations

Emission detail was selected via user preference. The output 

emissions detail does not affect the results of the modeling runs, 

therefore user preference is acceptable. 

Advanced Performance 

Features 

N/A

IV. Safety Margins

Since there is a significant difference between the projected emissions for the maintenance year 

and the attainment year a small portion of that difference was made into a safety margin. In 

other terms, the emissions for the attainment year are much greater than the emissions for the 

interim (2009) and maintenance (2018) years, which allows for a portion of those excess 

emissions to become a safety margin. A two tpd safety margin was added for NOx emissions for 

the 2009 and 2018 MVEBs. The MVEBs are presented below in Table 4. Revised MVEBs. 

The differences between the 2004 attainment year and the 2009 interim year and 2018 

maintenance year for NOx are found below in Table 5. NOx Emissions and Differences for 

Years 2004, 2009, and 2018. Table 4 presents decreases in emissions which are significant in 

some categories between the attainment, interim and maintenance years. Because the 2009 and 

2018 emissions are less than the 2004 attainment year emissions, a small portion of the excess 

emissions can be allocated to safety margins while the area can continue to attain the 1997 EightHour Ozone NAAQS. 

Table 4. Revised MVEBs

in TPD

Year 2009 2018

VOCs N/A N/A

NOx 29.0 14.9
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Table 5. NOx Emissions and Differences for Years 2004, 2009, and

2018 in TPD

Category 2004 2009 2004-2009 2018 2004-2018

Point 16.00 11.51 4.49 12.6 3.40

Area 2.12 2.31 -0.19 2.11 -0.01

Nonroad 10.30 8.40 1.90 5.40 4.90

Mobile 34.40 29.98 5.42 14.90 19.50

Total 62.82 51.20 11.62 35.01 27.81

C. EPA EVALUATION AND CONCLUSION:

EPA thoroughly evaluated the submittal made by Pennsylvania through PADEP. EPA’s detailed 

review has led us to conclude that the development methodology of the MVEBs is consistent 

with applicable guidance documents intended to guide the development of on-road inventories 

and MVEBs. EPA also reviewed the MVEBs using the adequacy criteria set forth in 40 CFR 

93.118(e)(4)(i)-(vi), and as documented above we found that the budgets meet all of the 

adequacy criteria. Based on the results of EPA’s in depth review of the SIP revision, the area’s 

continued attainment of the 1997 Eight-Hour Ozone NAAQS and the results of EPA’s review of 

the MVEBs using the adequacy criteria in the transportation conformity rule, EPA is proposing 

to approve the SIP revision.