PECHAN

5528-B Hempstead Way

Springfield, VA 22151

703-813-6700 telephone

703-813-6729 facsimile

3622 Lyckan Parkway

Suite 2002

Durham, NC 27707

919-493-3144 telephone

919-493-3182 facsimile

P.O. Box 1345

El Dorado, CA 95623

530-295-2995 telephone

530-295-2999 facsimile

Development of

the VISTAS Draft 2002

Mobile Source

Emission Inventory

(February 2004

Version) 

Prepared for:

VISTAS

59 Woodfin Place

Asheville, NC 28801

Prepared by:

Maureen A. Mullen

Kirstin B. Thesing

E.H. Pechan & Associates, Inc.

5528-B Hempstead Way

Springfield, VA 22151

February 9, 2004

Pechan Rpt. No. 04.01.002/9440.000
[This page intentionally left blank]
CONTENTS

Page

TABLES........................................................................................................................................ iv

FIGURES....................................................................................................................................... v

ACRONYMS AND ABBREVIATIONS.................................................................................... vi

I. INTRODUCTION/BACKGROUND ................................................................................ 1

II. ONROAD METHODS AND DATA.................................................................................. 2

A. 2002 VMT DEVELOPMENT..................................................................................... 2

1. Conversion to Annual VMT................................................................................. 2

2. Projection to 2002................................................................................................. 3

3. Splitting VMT by Road Type............................................................................... 4

a. Allocation of VMT to Vehicle Type using Default VMT Mix Data............. 4

b. Allocation of VMT to Vehicle Type using State-Provided VMT Mix Data . 6

c. Allocation of VMT by Month........................................................................ 6

B. 2002 ONROAD EMISSION FACTOR DEVELOPMENT USING MOBILE6.2 ..... 8

1. General MOBILE6.2 File Structure ..................................................................... 8

C. 2002 ONROAD EMISSION INVENTORY CALCULATIONS ............................. 17

D. DATA PROVIDED BY STATE AND LOCAL AGENCIES .................................. 17

1. Temperature........................................................................................................ 21

2. I/M and ATP Programs ...................................................................................... 21

3. RVP and Fuel Programs ..................................................................................... 21

III. NONROAD METHODS AND DATA............................................................................. 22

A. NONROAD MODEL CATEGORIES ...................................................................... 22

B. AIRCRAFT, COMMERCIAL MARINE VESSELS AND LOCOMOTIVES ........ 23

2. CMV Improvements........................................................................................... 28

a. Current Allocation Method.......................................................................... 28

b. Revised Port Allocation Method.................................................................. 29

3. Projection Methods............................................................................................. 40

IV. ONROAD REFUELING METHODS............................................................................. 42

A. CONTROLS .............................................................................................................. 42

B. METHODS................................................................................................................ 43

V. NONROAD REFUELING METHODS .......................................................................... 44

VI. SUMMARY OF RESULTS.............................................................................................. 45

A. ONROAD RESULTS................................................................................................ 45

B. NONROAD RESULTS............................................................................................. 47

VII. OBSERVATIONS AND RECOMMENDATIONS FOR IMPROVEMENT.............. 51

A. ONROAD SECTOR IMPROVEMENTS ................................................................. 51

B. NONROAD SECTOR IMPROVEMENTS .............................................................. 52

VIII. REFERENCES .................................................................................................................. 52
TABLES

Table II-1. VMT Data Provided by State/Local Agencies ............................................................ 3

Table II-2. VMT Growth Factors Used for Virginia ..................................................................... 4

Table II-3. Allocation of VMT from HPMS Vehicle Categories to MOBILE6 Vehicle Types for

2001........................................................................................................................................... 5

Table II-4. Default VMT Seasonal and Monthly Temporal Allocation Factors............................ 7

Table II-5. Default Speeds Modeled by Road Type and Vehicle Type....................................... 16

Table II-6. Summary of Onroad Data Provided by Alabama ...................................................... 18

Table II-7. Summary of Onroad Data Provided by Florida......................................................... 18

Table II-8. Summary of Onroad Data Provided by Georgia........................................................ 19

Table II-9. Summary of Onroad Data Provided by Kentucky..................................................... 17

Table II-10. Summary of Onroad Data Provided by Mississippi ................................................ 18

Table II-11. Summary of Onroad Data Provided by North Carolina .......................................... 18

Table II-12. Summary of Onroad Data Provided by South Carolina .......................................... 19

Table II-13. Summary of Onroad Data Provided by Tennessee.................................................. 19

Table II-14. Summary of Onroad Data Provided by Virginia ..................................................... 20

Table II-15. Summary of Onroad Data Provided by West Virginia............................................ 20

Table III-1. Summary of Comments by S/L/T Agencies on NONROAD Model Input Values

Distributed in July 2003.......................................................................................................... 22

Table III-2. Summary of S/L/T Agency Data Incorporated into the Draft VISTAS 2002 Other

Nonroad Inventory.................................................................................................................. 23

Table III-3a. Replacement Procedures for 1999 Locomotive Emissions for Pickens and

Tuscaloosa County, Alabama ................................................................................................. 24

Table III-3b. Replacement Procedures for 1999 Aircraft, Locomotive, and Commercial Marine

Vessel Emissions for Palm Beach County, Florida ................................................................ 25

Table III-3c. Replacement Procedures for 1999 Aircraft and Locomotive Emissions for

Davidson County, Tennessee.................................................................................................. 26

Table III-3d. Replacement Procedures for 1999 Aircraft, Locomotive, and Commercial Marine

Vessel Emissions for Sample Counties in Virginia ................................................................ 27

Table III-4. Port Areas Located in VISTAS and Adjoining States.............................................. 32

Table III-5. List of VISTAS Ports and Ports of Adjoining States ............................................... 33

Table III-6. Definition of Port Areas Obtained from Waterborne Commerce ............................ 36

Table III-7a. Growth Factors for Railroad Distillate Fuel Oil Use.............................................. 40

Table III-7b. 2002 National Rail Transportation Energy Use by Fuel Type............................... 41

Table III-8. Growth Factors for Commercial Marine Vessel Distillate and Residual Fuel 

Oil Use .................................................................................................................................... 42

Table IV-1. Onroad Stage II Control Programs........................................................................... 43

Table V-1. 2002 Draft Stage II Refueling Emissions by State.................................................... 45

Table VI-1. 2002 VISTAS Onroad Emissions and VMT by State.............................................. 46

Table VI-2. 1999 NEI Version 2 Onroad Emissions and VMT by State .................................... 46

Table VI-3. Change in Onroad Emissions and VMT from 1999 NEI Version 2 to VISTAS 2002

Inventory................................................................................................................................. 47

Table VI-4. 2002 VISTAS Annual Onroad Refueling Emissions............................................... 47

Table VI-5. Summary of Draft 2002 Nonroad Sector Annual Emissions by State ..................... 48

Table VI-6. Summary of Draft 2002 NONROAD Model Emission Estimates by State............. 49
Table VI-7. Summary of Draft 2002 Other Nonroad* Emission Estimates by State.................. 50

FIGURES

Figure II-1. Header Section of MOBILE6.2 Input File Including VOC Exhaust and PM10

Emission Factors............................................................................................................................. 9

Figure II-2. Header Section of MOBILE6.2 Input File Including VOC Evaporative and PM2.5

Emission Factors........................................................................................................................... 10

Figure II-3. Run Data Section of a MOBILE6.2 Input File......................................................... 11

Figure II-4. Run Data Section of a MOBILE6.2 Input File with Significant Local Inputs......... 11

Figure II-5. Sample Scenario for a Typical MOBILE6.2 Input File ........................................... 15

Figure III-1. VISTAS Region and Surrounding States, Underway NOx Emissions................... 30

Figure III-2. VISTAS Region and Surrounding States, Port NOx Emissions............................. 31

Figure III-3. VISTAS Region and Surrounding States, Revised Port Emissions of NOX............ 35
ACRONYMS AND ABBREVIATIONS

ATADS Air Traffic Activity Data System

ATP anti-tampering program

BTS Bureau of Transportation Statistics

BTU British thermal unit

CMV commercial marine vessels

CNG compressed natural gas

CO carbon monoxide

DOT Department of Transportation

EIA Energy Information Administration

EPA U.S. Environmental Protection Agency

FHWA Federal Highway Administration

FIPS Federal Information Processing Standards

GF growth factor

HDDV heavy-duty diesel vehicle

HDGV heavy-duty gasoline vehicle

HPMS Highway Performance Monitoring System 

I/M inspection and maintenance

LDDT light-duty diesel truck

LDDV light-duty diesel vehicle

LDGT light-duty gasoline truck

LDGV light-duty gasoline vehicle

LPG liquified petroleum gas

LTO landing and takeoff

MC motorcycle

mg milligram

NAPAP National Acid Precipitation Assessment Program

NEI National Emission Inventory

NH3 ammonia

NOx oxides of nitrogen

OTAQ Office of Transportation and Air Quality

Pechan E.H. Pechan & Associates, Inc.

PM2.5 particulate matter with an aerodynamic diameter less than or equal to 2.5 micrometers

PM10 particulate matter with an aerodynamic diameter less than or equal to 10 micrometers

ppmv parts per million volume

RFG reformulated gasoline

RVP Reid vapor pressure

SCC source classification code

S/L/T State/Local/Tribal

SO2 sulfur dioxide

USACE U.S. Army Corps of Engineers

VISTAS Visibility Improvement-State and Tribal Association of the Southeast

VMT vehicle miles traveled

VOC volatile organic compound
1

I. INTRODUCTION/BACKGROUND

The Visibility Improvement – State and Tribal Association of the Southeast (VISTAS) has

contracted with E.H. Pechan & Associates, Inc. (Pechan) to prepare a 2002 mobile source

emissions inventory. The purpose of this emissions inventory is to support the modeling and

assessment of speciated particulate matter with an aerodynamic diameter less than or equal to 2.5

micrometers (PM2.5). Through this contract, Pechan first prepared an inventory review

document. This document summarized several regional and national emission inventory efforts

and identified strengths and weaknesses associated with the use of these inventories in regional

haze modeling. This document also summarized data submittals by State and local air agencies

within the VISTAS region that could be used in the VISTAS 2002 mobile source emissions

inventory.

Since that time, the State and local air agencies have updated their submittals for the mobile

source sectors, including both onroad vehicles and nonroad engines. In July of 2003, Pechan

delivered sets of inputs to the NONROAD model option files and MOBILE6.2 input files and

vehicle miles traveled (VMT) data for each State and local agency to review. For the onroad

sector, the MOBILE6.2 input files and VMT data represented Pechan’s processing of the State

and local inputs in a consistent manner for use in calculating the 2002 onroad emissions

inventory. The MOBILE6.2 input files and VMT data included as much of the local data

supplied by the State and local agencies as possible, with missing information filled in with

appropriate default data. The data delivered by Pechan for the State and local agencies to review

related to the nonroad sector was primarily in the form of temperature and fuel data that would

be used as inputs to the NONROAD model. It should be noted that the nonroad sector inputs

were completed first and did not include some of the later temperature and fuel updates that did

get incorporated in the onroad data.

The State and local agencies were given a brief period to review, comment upon, and make

updated submittals to the onroad and nonroad inputs that were delivered in July 2003. After

receiving these comments and updated data, Pechan updated the appropriate MOBILE6.2 input

files, VMT data, and nonroad inputs with the revised State and local data. Pechan then

calculated 2002 onroad and nonroad emissions from these inputs. Pechan presented the

preliminary results of these emission inventories at a VISTAS meeting on August 28, 2003.

These draft August 2003 emission estimates, including inputs and methodology, were

documented in a draft report circulated to VISTAS in October 2003. This October 2003 report

also included documentation of draft 2002 refueling emissions from onroad and nonroad sources.

The VISTAS States were asked to review this document, as well as the supporting files provided

by Pechan, and provide comments or revisions by December 2003. Onroad and nonroad 2002

emissions for the VISTAS States have since been calculated based on the updates provided by

the States. This report documents the inputs and methodologies used in the February 2004

version of the VISTAS 2002 onroad and nonroad mobile source emission inventories. 
2

II. ONROAD METHODS AND DATA

A. 2002 VMT DEVELOPMENT

Table II-1 summarizes the type of VMT data submitted by each agency. Depending upon the

data submitted by the individual State or agency, up to three different procedures were

performed on the data. First, VMT data that were not provided at the annual level were

converted from daily VMT to annual VMT. Second, VMT provided for years other than 2002

were grown from the base year provided. Finally, the VMT were allocated by vehicle type, if

not already at that level of detail. The section discusses each of these procedures in more detail.

It should be noted that although the format and content of the VMT provided by the VISTAS

State and Local agencies varied significantly from agency to agency, this draft 2002 VISTAS

inventory is based at a minimum on county/roadway type specific VMT, as provided by the

individual agencies. This is a significant improvement over the spatial allocation methods used

in the U.S. Environmental Protection Agency’s (EPA’s) National Emission Inventory (NEI) for

onroad vehicles.

1. Conversion to Annual VMT

For use in the emission calculations, Pechan’s ultimate goal with the VMT data was to develop

an annual 2002 VMT database by county, roadway type, and vehicle type. As indicated in Table

II-1, the VMT data were submitted using three different time periods: annual, average annual

day, and summer day. No temporal adjustments were applied to VMT data submitted as annual

VMT. VMT data submitted as average annual day VMT were multiplied by 365 to convert from

an average day to the annual time period. The Jefferson County, Kentucky VMT were submitted

as summer day VMT. All annual VMT values were converted to units of millions of miles per

year. Therefore, any VMT values submitted as miles were divided by a factor of 1,000,000 and

VMT values submitted in units of 1,000 miles were divided by a factor of 1,000.

The Jefferson County, Kentucky VMT submittal included a single factor for converting the

summer day VMT to average annual day VMT. Thus, the Jefferson County summer day VMT

data were first multiplied by a factor of 0.97752 (the temporal conversion factor provided by

Jefferson County) to obtain average annual day VMT. The VMT data were then multiplied by

365 to obtain the annual VMT. 
3

Table II-1. VMT Data Provided by State/Local Agencies

State/Area

Time

Perio

d

2002

Actual

VMT by

County/Ro

ad

Type/Vehic

le Type

2002

Actual

VMT by

County/Ro

ad Type

2002

Projected

VMT by

County/Ro

ad Type

2002 VMT

from TDM

by

County/Ro

ad

Type/Vehic

le Type

1999

Actual

VMT by

County/Ro

ad

Type/Vehic

le Type

Alabama AAD X

Florida AAD X

Georgia AAD X

Kentucky AAD X

Jefferson County,

KY SD X

Mississippi ANN X

North Carolina AAD X

South Carolina ANN X

Tennessee AAD X

Virginia ANN X

West Virginia ANN X X

Time Period Codes: AAD=Average Annual Day, SD=Summer Day, ANN=Annual

2. Projection to 2002

As indicated in Table II-1, the Virginia VMT submittal was for a base year of 1999 rather than

2002. Thus, these VMT data needed to be projected to 2002 before calculating emissions. For

Virginia, growth factors were developed by roadway type for the period from 1999 to 2001

based on historical VMT data by roadway type from Table VM-2 “Functional System Travel” in

DOT’s Highway Statistics series (DOT, 1999 and 2001). The growth factors, presented in Table

II-2, were calculated by dividing Virginia’s 2001 VMT for each of the 12 roadway types from

Highway Statistics 2001 by the corresponding 1999 VMT from Highway Statistics 1999. For the

period from 2001 to 2002, the growth factors were developed using data obtained from the U.S.

Department of Transportation’s Traffic Volume Trends report (DOT, 2002). This monthly

publication provides a comparison of preliminary 2002 VMT estimates with comparable 2001

VMT. For several roadway types, these data are provided only at a national level. However, for

the combined rural interstates and arterials, these data are presented by State. The resultant data,

used to project the 2001 Virginia VMT to 2002, are shown in Table II-2. The 2001 to 2002

growth factors represent the 2002 VMT divided by the 2001 VMT, based on the data Virginia

for the rural interstates and arterials and on the national data for the remaining roadway types.

Once the growth factors were developed, the Virginia 1999 VMT data were first multiplied by

the appropriate 1999 to 2001 growth factor and then by the appropriate 2001 to 2002 growth

factor.
4

Table II-2. VMT Growth Factors Used for Virginia

Roadway Type

Roadway

Type

Portion

of SCC

Virginia 1999

to 2001 VMT

Growth

Factor

Virginia 2001

to 2002 VMT

Growth

Factor

Rural Interstate 110 1.043 1.035

Rural Other Principal Arterial 130 1.050 1.035

Rural Major Arterial 150 1.130 1.035

Rural Major Collector 170 0.982 1.011

Rural Minor Collector 190 1.032 1.011

Rural Local 210 0.923 1.011

Urban Interstate 230 1.050 1.024

Urban Other Freeway & Expressway 250 0.984 1.011

Urban Other Principal Arterial 270 1.061 1.011

Urban Minor Arterial 290 0.991 1.011

Urban Collector 310 0.925 1.013

Urban Local 330 0.690 1.013

Sources: U.S. Department of Transportation, Federal Highway Administration, “Traffic Volume Trends,

December 2002”, (http://www.fhwa.dot.gov/ohim/tvtw/tvtpage.htm); Highway Statistics 1999, and Highway

Statistics 2001 (http://www.fhwa.dot.gov/policy/ohpi/hss/hsspubs.htm)

3. Splitting VMT by Road Type

The final step in developing a consistent 2002 VMT data base was to allocate VMT from the

county and roadway type level of detail to the county/roadway type/vehicle type level of detail.

As shown in Table II-1, the Jefferson County, Kentucky; Mississippi; Virginia; and West

Virginia VMT data supplied for these jurisdictions already included the vehicle type level of

detail, so this final adjustment was not needed for these areas. For the remaining areas, some

provided VMT mix by vehicle type fractions while others provided no information on the

allocation of VMT by vehicle. In this latter case, default VMT fraction data from EPA’s

MOBILE6 model were used.

The States for which MOBILE6 default VMT mix data were used are: Alabama, Florida,

Georgia, Kentucky (excluding Boone County, Campbell County, Kenton County, and Jefferson

County), and South Carolina. It should be noted that Georgia initially provided VMT fractions

based on Georgia's HPMS classification count data, but after review of ten years of these data

determined that they are not reflecting the trend towards increasing travel by light trucks.

Georgia therefore decided it was more conservative to assume MOBILE6 default VMT fractions. 

a. Allocation of VMT to Vehicle Type using Default VMT Mix Data

To calculate 2002 VMT at the county/roadway type/vehicle type level using national default

data, the VMT totals by county and roadway type need to be allocated among the 28 MOBILE6

vehicle types. This was done based on the distribution of the 2001 rural and urban VMT among

the six Highway Performance Monitoring Systems (HPMS) vehicle types found in Table VM-1
5

(“Annual Vehicle Distance Traveled in Miles and Related Data - 1999 - by Highway Category

and Vehicle Type”) of the Federal Highway Administration’s (FHWA’s) Highway Statistics

2001 (http://www.fhwa.dot.gov/ohim/ hs01/index.htm) and a mapping of these HPMS vehicle

categories to the 28 MOBILE6 vehicle types. This mapping of the MOBILE6 vehicle types to

the HPMS vehicle types was developed by EPA’s Office of Transportation and Air Quality

(OTAQ) and is used in the development of the NEI. The data first needed to be expanded to the

28 vehicle type level of detail to obtain the proper cross reference between the HPMS and

MOBILE6 vehicle types since the eight vehicle types used in the final VISTAS VMT data base

cannot be directly mapped to the HPMS vehicle categories. First, the VMT totals for each of the

six HPMS vehicle categories were calculated as a fraction of the total VMT. This calculation

was performed separately for the rural VMT and the urban VMT. The resulting 2001 VMT

fractions for rural VMT and urban VMT are shown in Table II-3. Note that 2002 VMT are not

yet available at this level of detail. Using the default MOBILE6 VMT fractions for 2001 (since

the HPMS data represents 2001), taken from a MOBILE6 output file for 2001, the MOBILE6

VMT fractions were renormalized among all MOBILE6 vehicle types mapped to a given HPMS

vehicle category. This renormalization is shown in the final column of Table II-3. 

Table II-3. Allocation of VMT from HPMS Vehicle Categories to

MOBILE6 Vehicle Types for 2001

HPMS Vehicle Category

HPMS 2001

Rural VMT

Fractions

HPMS 2001

Urban VMT

Fractions

MOBILE6

Vehicle

Category

MOBILE6 2001

VMT Fractions by

HPMS Category

Passenger Cars 0.5454 0.6065 LDGV 0.9980

LDDV 0.0020

Motorcycles 0.0039 0.0031 MC 1.0000

Other 2-Axle 4-Tire Vehicles 0.3368 0.3375 LDGT1 0.1565

LDGT2 0.5211

LDGT3 0.1585

LDGT4 0.0729

LDDT12 0.0005

LDDT34 0.0032

HDGV2B 0.0658

HDDV2B 0.0216

Single-Unit 2-Axle 6-Tire or

More Trucks

0.0332 0.0212 HDGV3 0.0376

HDGV4 0.0206

HDGV5 0.0436

HDGV6 0.0934

HDGV7 0.0437

HDDV3 0.1023

HDDV4 0.0867

HDDV5 0.0380

HDDV6 0.2138

HDDV7 0.3205

Combination Trucks 0.0770 0.0300 HDGV8A 0.0001

HDGV8B 0.0000

HDDV8A 0.2191

HDDV8B 0.7808

Buses 0.0037 0.0017 HDGB 0.1920

HDDBT 0.3258
6

HDDBS 0.4822

Total 1.0000 1.0000

To calculate VMT by vehicle type, each VMT value representing a given county and road type

was multiplied by the product of the HPMS VMT fraction (selected depending upon whether the

road type represent VMT on rural or urban roads) and the corresponding MOBILE6 VMT

fraction by HPMS category. This process resulted in 28 VMT values at the county/roadway

type/vehicle type level of detail for each county/roadway type VMT value in the original VMT

file. 

As an example, Table II-3 shows that the HPMS Passenger Car vehicle category accounts for

54.54 percent of the total VMT on rural road types and that the MOBILE6 LDGV category

accounts for 99.8 percent of the VMT in the HPMS Passenger Car category. Therefore, a VMT

value representing rural interstates would be multiplied by 0.5454 times 0.9980 (0.5443), to

obtain the VMT total on rural interstates from LDGVs. Once all county/roadway type VMT

values were expanded to the corresponding set of values of VMT at the county/roadway type/28

MOBILE6 vehicle type level of detail, the VMT data base was then totaled at the eight vehicle

type level of detail (LDGV, LDGT1, LDGT2, HDGV, LDDV, LDDT, HDDV, MC). 

b. Allocation of VMT to Vehicle Type using State-Provided VMT Mix Data

Both North Carolina and Tennessee provided VMT mix data at the eight vehicle type level of

detail. The Tennessee data was provided for ten different county groupings, with a VMT mix

provided for six aggregated roadway type categories. North Carolina provided statewide VMT

mix fractions for each of the 12 roadway types. Since the VMT mix data for these two States

were already at the eight vehicle type level, the procedure for allocating VMT by vehicle type

was simpler than the procedure described above using the default data. Each county/roadway

type VMT value was matched to the corresponding VMT mix for that county and roadway type

and then separately multiplied by each of the eight VMT mix fractions to create eight VMT

values by county/roadway type/vehicle type that would sum to the original VMT value at the

county/roadway type level of detail.

c. Allocation of VMT by Month

The resulting annual county-level, vehicle, and roadway type-specific VMT data were

temporally allocated to months during the emission calculations. National Acid Precipitation

Assessment Program (NAPAP) temporal allocation factors were used to apportion the VMT to

the four seasons. Monthly VMT data were obtained using a ratio between the number of days in

a month and the number of days in the corresponding season. These temporal factors are shown

in Table II-4. Several States provided some level of information on temporal adjustment factors

for their VMT. These data were not used in this draft version of the 2002 VISTAS emission

inventory due to time constraints. However, any State or locally supplied temporal adjustment

factors will be included in the final version of the 2002 VISTAS onroad emission inventory.
7

Table II-4. Default VMT Seasonal and Monthly Temporal Allocation Factors

Roadway Seasonal VMT FactorsVehicle Type Roadway

Type

Winter Spring Summer Fall

LDV,LDT,MC Rural 0.2160 0.2390 0.2890 0.2560LDV,LDT,MC Urban 0.2340 0.2550 0.2650 0.2450HDV All 0.2500 0.2500 0.2500 0.2500Monthly VMT FactorsVehicle Type Roadway

Type

Jan Feb Mar Apr May Jun Jul Aug Sep O

LDV,LDT,MC Rural 0.0744 0.0672 0.0805 0.0779 0.0805 0.0942 0.0974 0.0974 0.0844 0.0LDV,LDT,MC Urban 0.0806 0.0728 0.0859 0.0832 0.0859 0.0864 0.0893 0.0893 0.0808 0.0HDV All 0.0861 0.0778 0.0842 0.0815 0.0842 0.0815 0.0842 0.0842 0.0842 0.0
8

B. 2002 ONROAD EMISSION FACTOR DEVELOPMENT USING

MOBILE6.2

The onroad emission factors used in the calculation of the VISTAS 2002 onroad emission

inventory were generated using EPA’s MOBILE6.2 emission factor model. In the development

of the MOBILE6.2 input files, Pechan attempted to include as much of the relevant data supplied

by the State and local agencies as possible, while at the same time, maintaining a generally

similar overall structure to the MOBILE6.2 input files, such that the output emission factors

could easily be matched to the appropriate VMT values. This section first discusses the overall

general structure of the MOBILE6.2 input files. This is followed by details explaining how this

general structure was adapted to include the State and local agency data and summaries of the

types of data provided by each agency.

1. General MOBILE6.2 File Structure

Each MOBILE6.2 input file is divided into three sections: the header section, the run data

section, and the scenario section. Information contained in the header section is primarily related

to defining the output format and content desired by the user. For the processing of the VISTAS

emission calculations, the database output format, aggregated to the daily level, was the desired

output format. In addition, for proper modeling of the VOC emissions, it was desired to

calculate the exhaust VOC emissions separately from the evaporative VOC emissions. However,

within the constraints of MOBILE6.2 in the daily aggregated database output format, it is not

possible to obtain evaporative and exhaust VOC emission factors broken out separately within

each scenario. It is also not possible to obtain emission factors for both PM10 and PM2.5 within a

single MOBILE6.2 scenario. Therefore, two sets of MOBILE6.2 input files were created—one

set to model VOC exhaust, NOx, CO, SO2, PM10, and NH3 emission factors and a second set to

model VOC evaporative and PM2.5 emission factors. Figure II-1 illustrates the header section of

a sample VISTAS MOBILE6.2 input file used to generate the VOC exhaust, NOx, CO, SO2,

PM10, and NH3 emission factors. Similarly, Figure II-2 illustrates the header section of a sample

VISTAS MOBILE6.2 input file used to generate the VOC evaporative and PM2.5 emission

factors. The primary difference between these two header sections is in the selection of the

emission types included, using the DATABASE EMISSIONS command and in the selection of

the pollutants to be included in the output. In Figure II-1, having the first two flags set to “2”

following the DATABASE EMISSIONS command indicates that the startup and running

exhaust emission factor components will be included in the output emission factor table. In

Figure II-2, the last six flags of the DATABASE EMISSIONS command line are set to “2” to

obtain the evaporative emission factor components in the emission factor output file. In Figure

II-2, the pollutants SO2 and NH3 are eliminated from the PARTICULATES command line, as the

emission factors for these pollutants will be reported in the output file resulting from the file

shown in Figure II-1.
9

MOBILE6 INPUT FILE : 

> HEADER 01 0012002 - EXHAUST - PM 10.0 

 

REPORT FILE : Vistas02/Output02/V0100110.TXT REPLACE 

DATABASE OUTPUT : 

WITH FIELDNAMES : 

DAILY OUTPUT : 

DATABASE EMISSIONS : 2211 1111 

PARTICULATES : SO4 OCARBON ECARBON GASPM LEAD SO2 NH3 BRAKE TIRE 

AGGREGATED OUTPUT : 

EMISSIONS TABLE : Vistas02/TB1_02/V0100110.TB1 REPLACE 

 

Figure II-1. Header Section of MOBILE6.2 Input File Including VOC Exhaust and

PM10 Emission Factors
10

MOBILE6 INPUT FILE : 

> HEADER 01 0012002 - EVAPORATIVE - PM 2.50 

 

REPORT FILE : Vistas02/Output02/V0100125.TXT REPLACE 

DATABASE OUTPUT : 

WITH FIELDNAMES : 

DAILY OUTPUT : 

DATABASE EMISSIONS : 1122 2222 

POLLUTANTS : HC 

PARTICULATES : ECARBON SO4 OCARBON GASPM LEAD BRAKE TIRE 

AGGREGATED OUTPUT : 

EMISSIONS TABLE : Vistas02/TB1_02/V0100125.TB1 REPLACE 

The next section of the MOBILE6 input files is the run data section. This section includes data

that applies to all scenarios in the input file. Figure II-3 shows an example of this section for a

county using default data. The only commands included in this example tell MOBILE6 that the

HC emission factors should be expressed in terms of VOC and that refueling emission factors

should be excluded from the output. It should be noted that refueling emissions were calculated

using a separate set of input files, but were excluded from the onroad input files here since

refueling emissions are included in the area source inventory rather than the onroad inventory.

Chapter IV discusses the onroad refueling MOBILE6 input files and emission calculations.

Comments in Figure II-3 indicate that this input file is using default registration distributions and

diesel sales fractions. For any input files that represent counties for which registration

distribution, diesel sales fractions, or trip length distributions have been provided or that have an

inspection and maintenance (I/M) program, anti-tampering program (ATP), or low emission

vehicle program in place in 2002, additional inputs are required in the run data section of the

MOBILE6.2 input file. Figure II-4 shows an example of an input file including all of these data.

Some of these data inputs are included directly in the MOBILE6.2 input file, while other data are

contained in external text files that are named by the commands in the run data section. For

questions regarding the specifics of any of the MOBILE6 input commands listed, the MOBILE6

User’s Guide should be consulted.

Figure II-2. Header Section of MOBILE6.2 Input File Including VOC Evaporative

and PM2.5 Emission Factors
11

RUN DATA : 

> 

 

EXPRESS HC AS VOC : 

NO REFUELING : 

 

* MOBILE6 Default Registration Distributions Applied 

* MOBILE6 Default Diesel Sales Fractions Applied 

RUN DATA : 

> 

 

EXPRESS HC AS VOC : 

NO REFUELING : 

 

REG DIST : Vistas02\ExtFiles\R02_ARLI.RDT 

* Diesel Sales Fractions Source File -

E:\TrendsM6_New\Vistas02\ExtFiles\D02_ARLI.DSF 

DIESEL FRACTIONS : 

0.0012 0.0023 0.0026 0.0027 0.0029 0.0015 0.0008 0.0011 0.0001 0.0006 

0.0013 0.0015 0.0006 0.0014 0.0006 0.0099 0.0087 0.0446 0.0685 0.0857 

0.1922 0.1481 0.1132 0.0959 0.0126 

0.0056 0.0221 0.0167 0.0235 0.0126 0.0119 0.0206 0.0136 0.0155 0.0127 

0.0246 0.0206 0.0222 0.0184 0.0227 0.0115 0.0310 0.0568 0.0508 0.1211 

Figure II-3. Run Data Section of a MOBILE6.2 Input File

Figure II-4. Run Data Section of a MOBILE6.2 Input File with Significant Local

Inputs
12

0.1077 0.2126 0.0711 0.0286 0.0176 

0.0056 0.0221 0.0167 0.0235 0.0126 0.0119 0.0206 0.0136 0.0155 0.0127 

0.0246 0.0206 0.0222 0.0184 0.0227 0.0115 0.0310 0.0568 0.0508 0.1211 

0.1077 0.2126 0.0711 0.0286 0.0176 

0.0126 0.0126 0.0126 0.0126 0.0126 0.0126 0.0126 0.0115 0.0111 0.0145 

0.0115 0.0129 0.0096 0.0083 0.0072 0.0082 0.0124 0.0135 0.0169 0.0209 

0.0256 0.0013 0.0006 0.0011 0.0001 

0.0126 0.0126 0.0126 0.0126 0.0126 0.0126 0.0126 0.0115 0.0111 0.0145 

0.0115 0.0129 0.0096 0.0083 0.0072 0.0082 0.0124 0.0135 0.0169 0.0209 

0.0256 0.0013 0.0006 0.0011 0.0001 

0.1998 0.1998 0.1998 0.1998 0.1998 0.1998 0.1998 0.2578 0.2515 0.3263 

0.2784 0.2963 0.2384 0.2058 0.1756 0.1958 0.2726 0.2743 0.3004 0.2918 

0.2859 0.0138 0.0000 0.0000 0.0000 

0.6774 0.6774 0.6774 0.6774 0.6774 0.6774 0.6774 0.7715 0.7910 0.8105 

0.8068 0.8280 0.8477 0.7940 0.7488 0.7789 0.7842 0.6145 0.5139 0.5032 

0.4277 0.0079 0.0000 0.0000 0.0001 

0.8606 0.8606 0.8606 0.8606 0.8606 0.8606 0.8606 0.8473 0.8048 0.8331 

0.7901 0.7316 0.7275 0.7158 0.5647 0.3178 0.2207 0.1968 0.1570 0.0738 

0.0341 0.0414 0.0003 0.0000 0.0000 

0.4647 0.4647 0.4647 0.4647 0.4647 0.4647 0.4647 0.4384 0.3670 0.4125 

0.3462 0.2771 0.2730 0.2616 0.1543 0.0615 0.0383 0.0333 0.0255 0.0111 

0.0049 0.0060 0.0000 0.0000 0.0000 

0.6300 0.6300 0.6300 0.6300 0.6300 0.6300 0.6300 0.6078 0.5246 0.5767 

0.5289 0.5788 0.5617 0.4537 0.4216 0.4734 0.4705 0.4525 0.4310 0.3569 

0.3690 0.4413 0.3094 0.1679 0.1390 

0.8563 0.8563 0.8563 0.8563 0.8563 0.8563 0.8563 0.8443 0.7943 0.8266 

0.7972 0.8279 0.8177 0.7440 0.7184 0.7588 0.7567 0.7431 0.7261 0.6602 

0.6717 0.7344 0.6107 0.4140 0.3610 
13

0.9992 0.9992 0.9992 0.9992 0.9992 0.9992 0.9992 0.9989 0.9987 0.9989 

0.9977 0.9984 0.9982 0.9979 0.9969 0.9978 0.9980 0.9979 0.9976 0.9969 

0.9978 0.9982 0.9974 0.9965 0.9964 

1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 

1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 

1.0000 1.0000 1.0000 1.0000 1.0000 

0.9585 0.9585 0.9585 0.9585 0.9585 0.9585 0.9585 0.8857 0.8525 0.8795 

0.9900 0.9105 0.8760 0.7710 0.7502 0.7345 0.6733 0.5155 0.3845 0.3238 

0.3260 0.2639 0.0594 0.0460 0.0291 

 

> ANTI-TAMP PROG : E:\TrendsM6_New\Vistas02\ExtFiles\VA_ATP2002.ATP 

ANTI-TAMP PROG : 

89 68 50 22222 21111111 1 12 098. 22112222 

 

> Exhaust I/M - IDLE test program #1 

I/M PROGRAM : 1 1983 2050 2 TRC 2500/IDLE 

I/M MODEL YEARS : 1 1968 1980 

I/M VEHICLES : 1 22222 21111111 1 

I/M STRINGENCY : 1 35.0 

I/M COMPLIANCE : 1 98.0 

I/M WAIVER RATES : 1 2.0 2.0 

 

> Exhaust I/M - ASM final program #2 

I/M PROGRAM : 2 1983 2050 2 TRC ASM 2525/5015 PHASE-IN 

I/M MODEL YEARS : 2 1981 2050 

I/M VEHICLES : 2 22222 11111111 1 

I/M STRINGENCY : 2 35.0 
14

I/M COMPLIANCE : 2 98.0 

I/M WAIVER RATES : 2 2.0 2.0 

I/M EFFECTIVENESS : 0.94 0.94 0.94 

 

> Exhaust I/M - IDLE test program #1 

I/M PROGRAM : 3 1983 2050 2 TRC 2500/IDLE 

I/M MODEL YEARS : 3 1981 2050 

I/M VEHICLES : 3 11111 21111111 1 

I/M STRINGENCY : 3 35.0 

I/M COMPLIANCE : 3 98.0 

I/M WAIVER RATES : 3 2.0 2.0 

 

> Evap I/M - Gas Cap test program #3 

I/M PROGRAM : 4 1998 2050 2 TRC GC 

I/M MODEL YEARS : 4 1973 2050 

I/M VEHICLES : 4 22222 21111111 1 

I/M COMPLIANCE : 4 98.0 

I/M WAIVER RATES : 4 2.0 2.0 

 

94+ LDG IMP : Vistas02\ExtFiles\NLEVNE.D 

> WeekDay Trip Length Distribution 

WE DA TRI LEN DI : Vistas02\ExtFiles\WeekTLD2.wdt 

The third and final section of the MOBILE6.2 input files contains the scenario data. For this

VISTAS inventory, each speed and road type combination or speed distribution were modeled in

twelve consecutive scenarios representing the temperature and fuel properties applicable in each

month. Thus, if a State agency supplied an average speed/road type combination for each of the

12 HPMS road categories, the corresponding MOBILE6.2 input file would have 144 scenarios.

The first scenario would represent January temperature and fuel conditions at the speed and

MOBILE6 roadway type for the first speed/roadway type provided (typically rural interstates).

This would be followed by the February scenario modeled for the same speed and roadway type,
15

and so on through the twelfth scenario representing December conditions for the same speed and

roadway type combination. 

Figure II-5 illustrates a sample scenario from one of the VISTAS MOBILE6.2 input files. This

is the first scenario in the file—therefore, it represents January temperature and fuel conditions.

The month of a given scenario in the VISTAS MOBILE6.2 input files can be determined by the

last two digits of the SCENARIO RECORD command line. In this case, the last two digits are

“01” indicating January. It should be noted that the only options for the EVALUATION

MONTH command are “1” indicating January or “7” indicating July. For the VISTAS input

files, the EVALUATION MONTH was set to “1” for all months from January through June and

to 7 for months from July through December. When this flag is set to “1”, it indicates that

MOBILE6 will use a January registration distribution. When the flag is set to “7”, MOBILE6

ages the registration by a half year, applying a half year of fleet turnover to the distribution. The

EVALUATION MONTH setting can also affect the reductions from reformulated gas programs.

However, by including the SEASON command, as shown in Figure II-5, the EVALUATION

MONTH flag setting will not affect reformulated gasoline reductions. With the SEASON flag

set to “2”, winter reformulated gasoline rules will be applied in areas with a reformulated gas

program modeled (using the FUEL PROGRAM command). Summer reformulated gas rules and

reductions will be applied when the SEASON flag is set to “1” if reformulated gas has been

modeled. In all of the VISTAS input files, the SEASON flag was included for all areas, whether

or not a reformulated gasoline program was modeled. This flag has no effect when the FUEL

PROGRAM command is not used. The SEASON flag was set to “1” for the months of May

through September and to “2” for the remaining months.

SCENARIO RECORD : 010010215.0_M01 

>FV FILE: SCENARIO: 1 

CALENDAR YEAR : 2002 

EVALUATION MONTH : 1 

MIN/MAX TEMPERATURE: 38.0 60.0 

ALTITUDE : 1 

PARTICULATE EF : PMGZML.CSV PMGDR1.CSV PMGDR2.CSV PMDZML.CSV PMDDR1.CSV

PMDDR2.CSV 

SEASON : 2 

AVERAGE SPEED : 15.0 Arterial 

FUEL RVP : 12.5 

PARTICLE SIZE : 10.0 

DIESEL SULFUR : 500.0 

Figure II-5. Sample Scenario for a Typical MOBILE6.2 Input File
16

Local speed data were provided by the agencies in Georgia, Kentucky, North Carolina,

Tennessee, and Virginia. A set of 12 monthly scenarios was developed for each speed input for

these States, with one exception. The Northern Kentucky (Boone County, Campbell County,

and Kenton County) and Jefferson County, Kentucky inputs were speed distribution files, rather

than average speeds by individual roadway types (one for Northern Kentucky and one for

Jefferson County, Kentucky). In this case, only 12 scenarios were modeled in total in the

Jefferson County and Northern Kentucky input files, with the Jefferson County or Northern

Kentucky speed distribution referenced in each scenario, respectively. No speed information

was provided for Alabama, Florida, Mississippi, South Carolina, or West Virginia. The average

speeds modeled in these files were the default speeds used in the NEI. These speeds are shown

in Table II-5 and vary by both roadway type and vehicle category. It should be noted that

several agencies provided speed information for ramps. Since the VMT data file is organized by

SCC and no SCC currently exists for ramp VMT, the ramp speed information could not be used

directly. In some cases, the fraction of VMT occurring on ramps was provided. In these cases,

this information was combined with the freeway speeds, following the guidance in the

MOBILE6 user’s guide to determine the overall freeway speed including the ramp speed, at 34.6

mph (the assumed value for ramp speeds in MOBILE6), and the fraction of VMT occurring on

the ramps. 

Table II-5. Default Speeds Modeled by Road Type and Vehicle Type 

(mph)

Speed (mph) and MOBILE6 Road Type

HPMS Road Type

Light Duty

Vehicles

Light Duty

Trucks

Heavy Duty

Trucks

Rural Interstate 60 Freeway 55 Freeway 40 Freeway

Rural Principal Arterial 45 Arterial 45 Arterial 35 Arterial

Rural Minor Arterial 40 Arterial 40 Arterial 30 Arterial

Rural Major Collector 35 Arterial 35 Arterial 25 Arterial

Rural Minor Collector 30 Arterial 30 Arterial 25 Arterial

Rural Local 30 Arterial 30 Arterial 25 Arterial

Urban Interstate 45 Freeway 45 Freeway 35 Freeway

Urban Other Freeway and Expressway 45 Freeway 45 Freeway 35 Freeway

Urban Principal Arterial 20 Arterial 20 Arterial 15 Arterial

Urban Minor Arterial 20 Arterial 20 Arterial 15 Arterial

Urban Collector 20 Arterial 20 Arterial 15 Arterial

Urban Local Local Local Local

Another optional input included in the scenario section of the MOBILE6 input files is the VMT

mix by 16 MOBILE6 vehicle categories. These vehicle categories are based on the 28

MOBILE6 vehicle categories, but with gasoline and diesel vehicles of the same weight class

combined together. When no information was provided on VMT mix, the MOBILE6 defaults

were used. Local VMT mix information provided by Tennessee, Virginia, and Jefferson County,

Kentucky were included in the MOBILE6.2 input files. In some cases, the same VMT mix was

applied to all scenarios. In other cases, the VMT mixes were specific to roadway type, so the

VMT mix would vary according to the roadway type being represented in the scenario.
17

C. 2002 ONROAD EMISSION INVENTORY CALCULATIONS

Once the MOBILE6.2 input files were set up and run through the MOBILE6.2 model, onroad

emissions were calculated by multiplying the monthly VMT for a given county, roadway type,

and vehicle type by the emission factor modeled for the same month, county, vehicle type and

roadway type. Because the MOBILE6.2 input files were set up to create output files in the form

of database tables, the output is provided by each of the 28 MOBILE6 vehicle types. Thus, the

emission factors first were aggregated to the eight vehicle categories included in the VMT files.

This was done using the VMT Fraction data provided in each of the MOBILE6 output files. For

each of the MOBILE6 vehicle types included in one of the eight vehicle types needed, the VMT

fractions were renormalized within that category. These eight vehicle categories are sometimes

referred to as the MOBILE5 vehicle categories. For example, the LDGT1 and LDGT2

MOBILE6 vehicle categories are both included in the MOBILE5 LDGT1 category. In this case,

the MOBILE6 LDGT1 VMT fraction was divided by the sum of the MOBILE6 LDGT1 and

LDGT2 VMT fractions. The same was done with the MOBILE6 LDGT2 VMT fraction, so that

the renormalized MOBILE6 LDGT1 and LDGT2 VMT fractions should now sum to 1. Next,

these normalized VMT fractions were multiplied by the corresponding MOBILE6 emission

factor and all of these weighted emission factors for a given scenario, within a MOBILE5 vehicle

category were summed to obtain the weighted emission factors at the MOBILE5 vehicle

category level. The VMT fractions included in the MOBILE6 output files are affected by the

registration distribution, diesel sales fractions, and VMT mixes supplied in the MOBILE6.2

input files. Areas that used the MOBILE6 defaults for each of these inputs should all have the

same VMT fractions, although even in these cases, there are two sets of VMT fractions—one for

the months from January through June and another for the months July through December. This

occurs due to the aging of the registration distribution caused by the use of the EVALUATION

MONTH flag, as discussed above. These emission factors, now at the MOBILE5 vehicle

category level, were multiplied by the corresponding VMT values to obtain monthly emissions

by county, roadway type, and vehicle category. 

D. DATA PROVIDED BY STATE AND LOCAL AGENCIES

The sections above describe some of the data that was supplied by the VISTAS State and local

agencies for use in the development of the 2002 onroad emission inventory. Tables II-6 through

II-15 summarize the data supplied by each agency in a consistent fashion. These tables primarily

list the data that were actually used in this analysis. This section provides additional information

on the data supplied by these agencies as well discussing why some of the data supplied could

not be used.
18

Table II-6. Summary of Onroad Data Provided by Alabama

Data Element Data Supplied by Responsible Agency

VMT Data 2002 actual daily VMT by county/road type

MOBILE6 Input Files

MOBILE5 Input Files

VMT Mix Information

Counties by Temperature Region

Monthly Temperatures Monthly 2002 temperatures by county

RVP Data March-September RVP values

Speed Data

Registration Data

Fuel Information

I/M Program Information N/A

Other

Table II-7. Summary of Onroad Data Provided by Florida

Data Element Data Supplied by Responsible Agency

VMT Data 2002 actual daily VMT by county/road type

MOBILE6 Input Files

MOBILE5 Input Files

VMT Mix Information

Counties by Temperature Region Supplied counties in each of 3 temperature regions

Monthly Temperatures

RVP Data Summer RVP values provided

Speed Data

Registration Data

Fuel Information

I/M Program Information N/A

Other
19

Table II-8. Summary of Onroad Data Provided by Georgia

Data Element Data Supplied by Responsible Agency

VMT Data 2002 actual average annual daily VMT by county and

functional classification prepared by Georgia DOT 

MOBILE6 Input Files Provided MOBILE6 sample input files

MOBILE5 Input Files

VMT Mix Information

Counties by Temperature Region

Monthly Temperatures

RVP Data Provided summer RVP values

Speed Data Provided 2002 statewide speeds by road type (speeds

based on VMT-weighted average speeds, from a 2002

loaded highway network for the 13-county Atlanta area) 

Registration Data Provided one MOBILE6 registration distribution for 13-

county Atlanta area and one MOBILE6 registration

distribution for rest-of-state

Fuel Information Provided information on Georgia gasoline program,

applied to 25 counties

I/M Program Information Provided I/M inputs for 13-county Atlanta area in

MOBILE6 format

Other Provided VMT temporal adjustment factors by month

and day of week for each road type (not used in the

01/04 inventory)
20

Table II-9. Summary of Onroad Data Provided by Kentucky

Data Element Data Supplied by Responsible Agency

VMT Data 2002 actual daily VMT by county/road type

MOBILE6 Input Files Provided sample MOBILE6 input files for several counties

MOBILE5 Input Files

VMT Mix Information

Counties by Temperature

Region Provided temperature stations to be used for several counties

Monthly Temperatures

RVP Data Provided summer RVP for several counties

Speed Data

Provided average speed by road type for several county

groupings

Registration Data

Fuel Information Verified counties in reformulated gasoline program

I/M Program Information I/M program information provided

Other

Jefferson County,

Kentucky

Data Element Data Supplied by Responsible Agency

VMT Data

2002 summer day VMT from TDM by county/road type/vehicle

type

MOBILE6 Input Files

Provided MOBILE6 input files representing the four different

vehicle control combinations found in Jefferson County

MOBILE5 Input Files

VMT Mix Information Provided Jefferson County VMT mix in MOBILE6 format

Counties by Temperature

Region

Monthly Temperatures Provided 2002 actual monthly temperature data for Louisville area

RVP Data Provided summer and winter RVP values

Speed Data Provided speed distribution file for Jefferson County

Registration Data

Provided registration distribution for Jefferson County in MOBILE6

format

Fuel Information Reformulated gasoline modeled

I/M Program Information I/M program information provided

Other Provided absolute humidity data

Boone County, Campbell County, and Kenton County, Kentucky

Data Element Data Supplied by Responsible Agency

VMT Data 2002 actual daily VMT by county/road type

MOBILE6 Input Files

MOBILE5 Input Files Provided MOBILE5 input file for Northern Kentucky counties

VMT Mix Information

Counties by Temperature

Region

Monthly Temperatures

RVP Data Provided summer and winter RVP values

Speed Data Provided speed distribution file for Northern Kentucky

Registration Data

Provided registration distribution for Northern Kentucky in

MOBILE6 format—LDGVs and LDGT1s only

Fuel Information Reformulated gasoline modeled

I/M Program Information I/M program information extracted from MOBILE5 input file

Other Provided Northern Kentucky VMT distributions by facility type and
21

by hour in MOBILE6 format
22

Table II-10. Summary of Onroad Data Provided by Mississippi

Data Element Data Supplied by Responsible Agency

VMT Data Provided 2002 actual annual VMT by county/road type/vehicle type

MOBILE6 Input Files

MOBILE5 Input Files

VMT Mix Information

Counties by Temperature

Region

Monthly Temperatures

RVP Data Provided statewide RVP by season

Speed Data

Registration Data

Fuel Information

I/M Program Information N/A

Other

Table II-11. Summary of Onroad Data Provided by North Carolina

Data Element Data Supplied by Responsible Agency

VMT Data 2002 actual daily VMT by county/road type

MOBILE6 Input Files

MOBILE5 Input Files

VMT Mix Information

Counties by Temperature Region Indicated counties within each of several

temperature regions in state

Monthly Temperatures

RVP Data

Speed Data Provided average speed data by road type for

several groups of counties and rest-of-state

Registration Data Provided registration data for several groups of

counties and rest-of-state based on 2001 data

Fuel Information

I/M Program Information Provided written description of I/M program

Other
23

Table II-12. Summary of Onroad Data Provided by South Carolina

Data Element Data Supplied by Responsible Agency

VMT Data 2002 actual annual VMT by county/road type

MOBILE6 Input Files

MOBILE5 Input Files

VMT Mix Information

Counties by Temperature Region Supplied counties in each of 7 temperature regions

Monthly Temperatures

RVP Data

Speed Data

Registration Data

Fuel Information

I/M Program Information N/A

Other

Table II-13. Summary of Onroad Data Provided by Tennessee

Data Element Data Supplied by Responsible Agency

VMT Data 2002 actual daily VMT by county/road type

MOBILE6 Input Files

Provided MOBILE6 input files for groups of counties

covering state

MOBILE5 Input Files

VMT Mix Information Provided VMT mix fractions by road type

Counties by Temperature Region

Monthly Temperatures

RVP Data Provided summer RVP information

Speed Data

Provided average speed data by road type for

groups of counties 

Registration Data Provided registration data for most counties

Fuel Information

I/M Program Information Provided in MOBILE6 input files

Other
24

Table II-14. Summary of Onroad Data Provided by Virginia

Data Element Data Supplied by Responsible Agency

VMT Data 1999 actual annual VMT by county/road type/vehicle type

MOBILE6 Input Files Provided MOBILE6 input files for representative counties

MOBILE5 Input Files

VMT Mix Information

Counties by

Temperature Region

Provided listing of counties within each of several temperature regions

Monthly Temperatures

RVP Data Provided summer RVP data

Speed Data Speed data provided for each VMT record

Registration Data 2002 county-level registration data provided for nonattainment

counties

Fuel Information Verified counties in reformulated gasoline program

I/M Program Information I/M and ATP inputs provided in MOBILE6 formats; verified counties

that implement I/M

Other LEV progam modeled statewide; provided diesel sales fractions

Table II-15. Summary of Onroad Data Provided by West Virginia

Data Element Data Supplied by Responsible Agency

VMT Data 2002 actual annual VMT by county/road

type/vehicle type

MOBILE6 Input Files Supplied several sample MOBILE6 input

files

MOBILE5 Input Files

VMT Mix Information VMT data included vehicle type splits

Counties by Temperature Region Supplied counties in each of 4

temperature regions

Monthly Temperatures

RVP Data Supplied summer RVP value statewide

Speed Data Supplied speed data in MOBILE6 input

files--speed data determined to be

inappropriate for this analysis

Registration Data

Fuel Information

I/M Program Information N/A

Other
25

1. Temperature

The default average daily maximum and minimum temperature data for each month used in this

analysis was obtained from the National Climatic Data Center. This temperature data was actual

2002 data. It should be noted that a number of agencies provided information on ozone season

or summer temperatures. This information could not be used in this analysis, as the ozone

season temperature data are based on several years of temperature data and do not represent the

average daily minimum and maximum monthly temperatures that were needed for this analysis.

Information was provided by Alabama, Kentucky, North Carolina, South Carolina, Virginia, and

West Virginia related to monthly temperature. In some cases, this data divided the counties

within the State into several temperature regions and listing a city that should be used for

obtaining the temperature data. In these cases, a temperature station from the National Climatic

Data Center database was selected from the desired city, and this corresponding temperature set

was applied to the counties listed by the States. Several of the States provided their own full set

of 2002 temperature data either Statewide or by county. These data were included in the

analysis, replacing the default temperature data for those States.

2. I/M and ATP Programs

Several agencies provided I/M and ATP inputs in the form of MOBILE5 input files. Pechan

converted these inputs to MOBILE6 inputs, following the guidance in the MOBILE6 user’s

guide. Agencies that provided the data in MOBILE5 format should review the MOBILE6 I/M

and ATP inputs carefully to make sure that the conversions fully capture the actual programs as

they were implemented in 2002. In addition, from information provided by North Carolina,

Tennessee, and Jefferson County, Kentucky, the I/M and ATP programs should only be applied

to a portion of the VMT in the corresponding counties. For the North Carolina and Tennessee

I/M counties, duplicate MOBILE6.2 input files were created that eliminate the I/M and ATP

programs. The VMT from these counties was divided according to the fraction of the VMT

subject to I/M and the fraction of the VMT not subject to I/M. These fractions were provided by

the corresponding agencies in North Carolina and Tennessee. The VMT data for each I/M

county was then divided according to these VMT fractions to obtain one set of VMT for the

portion of vehicles subject to I/M and another set for those not subject to I/M. The emission

factors from the I/M files were multiplied by the portion of the VMT subject to I/M while the

emission factors from the files without the I/M were multiplied by the remaining portion of the

VMT. In Jefferson County, Kentucky, a similar procedure was followed. However, in this case,

the county also has a significant portion of VMT from vehicles registered in Indiana that are not

subject to I/M or that do not have reformulated gasoline. Thus, the Jefferson County VMT was

divided into four subsets and four MOBILE6 input files were developed representing the four

groups of vehicle types traveling in the county.

3. RVP and Fuel Programs

Default RVP by county and month were obtained from the data used in the 2002 NEI. The NEI

fuel data are based on year 2000 fuel survey data for January and July, with data for intermediate

months calculated by interpolation. RVP data for July were applied from May through

September, the months when Phase II RVP regulations are in effect. For States that supplied
26

July, summer, or ozone season RVP values, these values were also applied from May through

September. If winter RVP values were supplied, these values were applied directly in each of

the remaining months. As mentioned above, reformulated gasoline programs were modeled

where appropriate. Georgia provided additional fuel inputs to capture the RVP and sulfur

content values of its low sulfur gasoline program. 

III. NONROAD METHODS AND DATA

A. NONROAD MODEL CATEGORIES

Pechan used EPA’s draft NONROAD2002a model to generate 2002 annual emissions for the

majority of nonroad engines. To improve the accuracy of these model runs, we asked State/

Local/Tribal (S/L/T) contacts to provide seasonal or monthly gasoline Reid Vapor Pressure

(RVP) and temperature; appropriate data on reformulated gasoline (RFG), oxygenated fuel and

Stage II programs, and diesel fuel sulfur levels. In addition, to improve the activity data inputs,

we asked whether S/L/T agencies had collected information on equipment populations or activity

(e.g., hours of use or load factors) to use in place of default populations in the NONROAD

model. No S/L/T agencies provided activity data to replace the model defaults.

Seasonal average RVP and average, maximum and minimum temperature values were calculated

based on the county-level, monthly RVP and temperature data set prepared for onroad mobile

sources. Information on RFG programs and oxygenated fuels programs obtained for the onroad

mobile sector was also used. In July 2003, Pechan distributed the input values (RVP, percent

O2, temperature, and Stage II control efficiency) to be used for the draft NONROAD model

2002 inventory for review and comment by the VISTAS S/L/T agencies. Pechan obtained

comments from the S/L/T agencies listed in Table III-1.

Table III-1. Summary of Comments by S/L/T Agencies on NONROAD Model Input

Values Distributed in July 2003

State Comment

Alabama Provided region specific data to replace the statewide default values for RVP and

ambient temperature

Georgia Changed oxygen weight percent to zero for all counties 

Kentucky No Stage II programs in Bullitt and Oldham Counties

Tennessee Revised RVP value for Davidson County

Mississippi Revised statewide RVP by season

Virginia No Stage II program in Charles City County

Additional comments on the August 2003 NONROAD model temperature and RVP inputs were

incorporated for consistency with data submitted for the onroad mobile modeling (e.g., North

Carolina). In addition, the State of West Virginia provided revised geographic allocation files

for certain nonroad categories to improve upon the NONROAD model’s default county

allocation.

Using the inputs shown in the file “VISTAS NONROAD County Inputs.xls,” Pechan prepared

seasonal option files for each of four seasons (winter, spring, summer, and autumn), and ran the
27

NONROAD model at the county level. Model default values were used for all other inputs, with

the exception of diesel fuel sulfur. A value of 2,500 parts per million volume (ppmv) was used

instead of the default 2,318 ppm, since the default represented a national average including

California’s lower diesel fuel sulfur level. Pechan summed the seasonal results, and then

processed the model output to develop a county-level, SCC-level annual emissions inventory for

all pollutants except NH3. 

The NH3 emissions for NONROAD model categories were developed using the following

procedures. OTAQ recently reviewed the basis of NH3 data summarized in a report entitled,

“A Study of the Potential Impact of Some Unregulated Motor Vehicle Emissions” (Harvey,

1983). In conducting this review, OTAQ performed an analysis of the available light-duty

noncatalyst engine data to develop defensible gasoline nonroad emission factors on a mg/gallon

basis (Harvey, 2003). For both gasoline noncatalyst and diesel engines, fuel based emission

factors were developed from emission factors expressed on a gram/mile basis by accounting for

the reported fuel economy of each tested engine. For gasoline non-catalyst engines, this resulted

in a value of 115.8 mg/gallon, which is applied to county-level fuel consumption estimates for

2-stroke gasoline, 4-stroke gasoline and liquified petroleum gas (LPG) equipment. From the

diesel engine test data, a value of 83.3 mg/gallon was derived, which is applied to diesel fuel

consumption estimates. County-level fuel consumption for these engines, expressed in gallons,

is an output from EPA’s NONROAD model. 

B. AIRCRAFT, COMMERCIAL MARINE VESSELS AND

LOCOMOTIVES

For 2002 aircraft, commercial marine vessels (CMVs), and locomotives, Pechan used 1999

emission estimates developed for EPA’s 1999 NEI Version 2 as base year estimates for the

VISTAS region. These categories are not included in the NONROAD model, and are hereafter

referred to as “other nonroad.” Pechan then incorporated revised S/L/T estimates summarized in

Table III-2, using the replacement procedures summarized in Tables III-3a through III-3d.

Pechan tracked changes by labeling the default 1999 NEI records as Version 2 (V2) and the

revised S/L/T records as Version 3 (V3). In cases where PM2.5 estimates were not provided,

they were developed using the following category-specific fractions applied to the available

PM10 emission estimates: 1) Aircraft: 0.69; 2) Locomotive: 0.90; and 3) CMV: 0.92 (EPA,

2002). Commercial marine adjustments are described in detail in the following section.

Table III-2. Summary of S/L/T Agency Data Incorporated into the Draft VISTAS

2002 Other Nonroad Inventory

State Description of Inventory Pollutants

Alabama 1999 Locomotive emissions for Pickens and Tuscaloosa

counties

VOC, NOx, and CO

Florida 2001 Aircraft, Locomotive and Commercial Marine Vessel

emissions for Palm Beach County 

VOC, NOx, CO, PM10,

and SOx

Tennessee 1999 Aircraft and Locomotive emissions for Davidson County VOC, NOx, CO, SOx, and

primary PM10

Virginia 1999 Statewide Inventory for Aircraft, Locomotive and

Commercial Marine Vessels

VOC, NOx, CO
28

Table III-3a. Replacement Procedures for 1999 Locomotive Emissions for

Pickens and Tuscaloosa County, Alabama

STATE

_

FIPS

COUNTY

_

FIPS SCC

Versi

on Notes

START_

DATE

END_

DATE

VO

C NOX CO

01 107

22850020

05 V3 7.73 179.7

22.8

1

01 107

22850020

05 V2

Replace VOC, NOx, and

CO emissions 19990101 19991231

196

2.9

4564

3

579

4.5

01 107

22850020

10 V3 5.39 53.48 9.47

01 107

22850020

10 V2

Replace VOC, NOx, and

CO emissions 19990101 19991231 5.39 53.48 9.48

01 125

22850020

05 V3

16.3

1

379.1

5

48.1

3

01 125

22850020

05 V2

Replace VOC, NOx, and

CO emissions 19990101 19991231

338

4.9

7871

1.4

999

2.6

01 125

22850020

10 V3 9.29 92.15

16.3

3

01 125

22850020

10 V2

Replace VOC, NOx, and

CO emissions 19990101 19991231 9.29 92.15

16.3

3
29

Table III-3b. Replacement Procedures for 1999 Aircraft, Locomotive, and Commercial Marine V

for Palm Beach County, Florida

STATE

_

FIPS

COUNTY_

FIPS SCC Version Notes

START_

DATE

END_

DATE VOC NOX CO 

12 099 2275000000 V3 Apply a Growth Factor to 2001

state-supplied aircraft emissions tobackcast to 1999Estimate PM2.5-PRI off PM10-PRI

19990101

1999123

1

470.39 805.94

4,121.

41

12 099 2275001000 V2 Delete all records for this SCC 19990101

1999123

1

0.44 0.05 9.03 

12 099 2275020000 V2 Delete all records for this SCC 19990101

1999123

1

79.1 275.5 330.6 

12 099 2275050000 V2 Delete all records for this SCC 19990101

1999123

1

13.93 2.37 437.43 

12 099 2275060000 V2 Delete all records for this SCC 19990101

1999123

1

9.23 1.19 212.32 

12 099 2280000000 V3 Apply a Growth Factor to 2001

state-supplied cmv emissions tobackcast to 1999Estimate PM2.5-PRI off PM10-PRI

19990101

1999123

1

10.42 115.60 0.97 

12 099 2280002100 V2 Delete all records for this SCC 19990101

1999123

1

25.5 815.4 107.51 

12 099 2280002200 V2 Delete all records for this SCC 19990101

1999123

1

0.22 7.05 0.93 

12 099 2280003100 V2 Delete all records for this SCC 19990101

1999123

1

6.8 217.5 28.63 

12 099 2280003200 V2 Delete all records for this SCC 19990101

1999123

1

0.06 1.93 0.25 

12 099 2285002000 V3 Apply a Growth Factor to 2001

state-supplied locomotive emissionsto backcast to 1999Estimate PM2.5-PRI off PM10-PRI

19990101

1999123

1

28.19 658.78 83.64 

12 099 2285002006 V2 Delete all records for this SCC 19990101 6.11 164.1 16.17 
30

1999123

1

12 099 2285002008 V2 Delete all records for this SCC 19990101

1999123

1

0.45 12.15 1.2 

12 099 2285002009 V2 Delete all records for this SCC 19990101

1999123

1

6.78 182.2 17.95 

12 099 2285002010 V2 Delete all records for this SCC 19990101

1999123

1

3.75 64.36 6.77 

1 Palm Beach County provided emission estimates corresponding to 2001; as such, 2001 emission estimates were backcast to 1999 using growth factors 

before incorporation.
31

Table III-3c. Replacement Procedures for 1999 Aircraft and Locomotive Emissions for

Davidson County, Tennessee

STAT

E_

FIPS

COUNT

Y_

FIPS SCC

Versi

on Notes

START_

DATE

END_

DATE VOC NOX CO

SO

2

PM1

0-

PRI

PM2

5-

PRI

47 037

22750000

00 V3

Estimate PM2.5-PRI off

PM10-PRI

1999010

1

1999123

1

232.12

5 634.35 1766

32.

13

39.2

5

47 037

22750010

00 V2

Delete all records for this

SCC

1999010

1

1999123

1 1.7 0.2 35

0.0

2 0.75 0.52

47 037

22750200

00 V2

Delete all records for this

SCC

1999010

1

1999123

1 187.45 649.92

782.

93

62.

34

47 037

22750500

00 V2

Delete all records for this

SCC

1999010

1

1999123

1 4.72 0.8

148.

3

0.1

2 2.92 2.02

47 037

22750600

00 V2

Delete all records for this

SCC

1999010

1

1999123

1 15.22 1.97

349.

97

0.1

9 7.51 5.18

47 037

22850020

00 V3

Estimate PM2.5-PRI off

PM10-PRI

1999010

1

1999123

1 20.803

363.11

7

50.7

01

26.

36

8.89

3

47 037

22850020

06 V2

Delete all records for this

SCC

1999010

1

1999123

1 31.91 857.26

84.4

6

53.

6

21.2

7

19.1

5

47 037

22850020

10 V2

Delete all records for this

SCC

1999010

1

1999123

1 19.6 336.23

35.3

9

15.

68 8.54 7.69
32

Table III-3d. Replacement Procedures for 1999 Aircraft, Locomotive, and

Commercial Marine Vessel Emissions for Sample Counties in Virginia

STAT

E_

FIPS

COUNT

Y_

FIPS SCC

Versi

on Notes

START

_

DATE

END_

DATE VOC

NO

X CO

S

O

2

PM

10-

PRI

PM

25-

PRI

51 001

22750010

00

V3

199901

01

199912

31

3.47 0.78 3.74

51 001

22750010

00

V2 Replace VOC, NOx, and CO emissions

Keep SO2, PM10-PRI, and PM2.5-PRI

emissions

199901

01

199912

31

0.31 0.04 6.38 0 0.14 0.09

51 013

22750200

00

V3

199901

01

199912

31

145.8

21

992.

23

163

4.2

51 013

22750200

00

V2 Replace VOC, NOx, and CO emissions

Keep SO2 emissions 199901

01

199912

31

271.1

7

940.

36

113

2.7

9

0.

2

51 001

22750500

00

V3

199901

01

199912

31

1.25 0.21

39.3

4

51 001

22750500

00

V2 Replace VOC, NOx, and CO emissions

Keep SO2, PM10-PRI, and PM2.5-PRI

emissions

199901

01

199912

31

0.25 0.04 7.81

0.

0

1

0.15 0.11

51 001

22750600

00

V3

199901

01

199912

31

0.05 0.01 1.26

51 001

22750600

00

V2 Replace VOC, NOx, and CO emissions

Keep SO2, PM10-PRI, and PM2.5-PRI

emissions

199901

01

199912

31

1.47 0.19 33.8

0.

0

2

0.72 0.5

51 670

22800020

00

V3 Add SCC to the Inventory

199901

01

199912

31

3.3

18.1

6

6.94

51 670

22800021

00

V2 Sum up SO2, PM10-PRI, and PM2.5-

PRI emissions for SCCs 2280002100

and 2280002200 and add to SCC

280002000. After that, delete all records

for SCC 2280002100 and 2280002200

199901

01

199912

31

10.12

323.

52

42.6

6

1

4.

7

13.6

1

12.5

2

51 670

22800022

00

V2 Sum up SO2, PM10-PRI, and PM2.5-

PRI emissions for SCCs 2280002100

and 2280002200 and add to SCC

2280002000. After that, delete all

records for SCC 2280002100 and

2280002200

199901

01

199912

31

0.17 5.39 0.71

0.

2

4

0.23 0.21

51 670

22800030

00

V3 Add SCC to the Inventory

199901

01

199912

31

0.14 1.64 0

51 670

22800031

00

V2 Sum up SO2, PM10-PRI, and PM2.5-

PRI emissions for SCCs 2280003100

and 2280003200 and add to SCC

2280003000. After that, delete all

records for SCC 2280003100 and

2280003200

199901

01

199912

31

2.7

86.3

1

11.3

6

4

5.

9

3.76 3.46

51 670

22800032

00

V2 Sum up SO2, PM10, and PM2.5

Emissions for SCCs 2280003100 and

2280003200 and add to SCC

2280003000. After that, delete all

records for SCC 2280003100 and

2280003200

199901

01

199912

31

0.05 1.48 0.19

1.

0

9

0.08 0.08

51 199

22830020

00

V3

199901

01

199912

31

8.46

53.4

7

15.5

1
33

STAT

E_

FIPS

COUNT

Y_

FIPS SCC

Versi

on Notes

START

_

DATE

END_

DATE VOC

NO

X CO

S

O

2

PM

10-

PRI

PM

25-

PRI

51 199

22830020

00

V2 Replace VOC, NOx, and CO emissions

199901

01

199912

31

7.43

47.2

6

13.6

3

51 740

22850020

05

V3 Add SCC to the Inventory

199901

01

199912

31

3.76

100.

99

9.95

51 740

22850020

06

V2 Sum up SO2, PM10-PRI, and PM2.5-

PRI emissions for SCCs 2285002006

and 2285002007 and add to SCC

285002005. After that, delete all records

for SCC 2285002006 and 2285002007.1

199901

01

199912

31

0.7

18.7

7

1.85

1.

1

7

0.47 0.42

51 740

22850020

07

V2 Sum up SO2, PM10-PRI, and PM2.5-

PRI emissions for SCCs 2285002006

and 2285002007 and add to SCC

285002005. After that, delete all records

for SCC 2285002006 and 2285002007.1

199901

01

199912

31

0.08 2.26 0.22

0.

1

4

0.06 0.05

51 036

22850020

10

V3

199901

01

199912

31

0.59

10.1

3

1.06

51 036

22850020

10

V2 Replace VOC, NOx, and CO emissions

Keep SO2, PM10-PRI, and PM2.5-PRI

emissions

199901

01

199912

31

1.99

34.1

5

3.59

1.

5

9

0.87 0.78

1 Other counties may also have emissions for SCCs 2285002008 and 2285002009. In these cases, sum up SO2, PM10-PRI, and PM2.5-PRI

emissions for SCCs 2285002006, 2285002007, 2285002008, and 2285002009 and add to SCC 2285002005. After that, delete all records for SCC

2285002006, 2285002007, 2285002008, and 2285002009.
34

2. CMV Improvements

This section describes procedures for improving the spatial distribution of CMV emission

estimates for the VISTAS region. States that share borders with non-VISTAS States along the

Mississippi and Ohio Rivers have expressed concern about the representativeness of port

emission estimates at a county-level. Revising the county-level emissions estimates would allow

more accurate modeling of emissions in the VISTAS States.

Ideally, CMV emission estimates would be developed using local activity data that account for

vessel type, engine type and mode of operation (cruise, maneuvering, and hotelling). Creating

this type of “bottom-up” emission inventory requires a large amount of effort. Therefore, Pechan

utilized port-specific emission estimates developed for the 1999 NEI, distributed using a revised

allocation methodology, which incorporates information on the number of port facilities in each

county. 

a. Current Allocation Method

The current 2002 VISTAS commercial marine inventory is based on EPA’s 1999 NEI Version

2.0, projected to 2002 using appropriate growth factors. State-supplied data were incorporated

by EPA or by Pechan for some VISTAS States for this category, including Alabama, Virginia,

West Virginia, and Palm Beach County, Florida.

The 1999 NEI estimated emissions for these categories according to the following SCCs:

SCC Descriptor 1 Descriptor 3 Descriptor 6 Descriptor 8

2280002100 Mobile Sources Marine Vessels, Commercial Diesel Port emissions

2280002200 Mobile Sources Marine Vessels, Commercial Diesel Underway emissions

2280003100 Mobile Sources Marine Vessels, Commercial Residual Port emissions

2280003200 Mobile Sources Marine Vessels, Commercial Residual Underway emissions

For the 1999 NEI, commercial marine diesel emissions were developed by obtaining 2000

emission estimates for all pollutants except SO2 from OTAQ’s marine diesel regulatory

background documentation (Draft Regulatory Impact Analysis - Control of Emissions from

Compression-Ignition Marine Engines). To estimate emissions for 1999, 2000 estimates were

backcast using growth factors obtained from the draft RIA cited above. Steam-powered residual

CMV emission estimates were developed by obtaining fuel usage data from OTAQ and applying

fuel-based emission factors (EPA, 1989). A similar method was used for diesel SO2 emissions.

National diesel usage was estimated assuming a sulfur content of 0.25 percent and EPA emission

factors (EPA, 2002).

National diesel emissions were disaggregated into port and underway emissions estimates based

on the assumption that 75 percent of distillate fuel is consumed within the port, while the

remaining fuel is consumed while underway, consistent with EPA guidance. National residual

emissions were disaggregated into port and underway emissions estimates based on the

assumption that 25 percent of residual fuel is consumed within the port, while the remaining fuel

is consumed while underway (EPA, 1989).
35

To allocate to counties, port emissions were assigned to the 150 largest U.S. ports based on

activity obtained from the U.S. Army Corps of Engineers (USACE). The percentage of total

traffic for each port was calculated by dividing the port-level traffic by the total traffic.

Emissions for each port were then assigned to a single county. 

Underway emissions are assigned to counties based on a county=s shipping lane traffic. The

Bureau of Transportation Statistics’ (BTS=) National Transportation Atlas Databases-1999

contains data on the thousand tons per mile traveled for each shipping lane link in the United

States (BTS-CD26). Where navigable rivers form a county or State boundary, the shipping lane

traffic is proportioned to individual counties based on the length of shoreline that is shared. For

example, if two counties share a navigable river, and both counties have the same length of

shoreline, the shipping traffic is split evenly between the two counties. Shipping lanes that are

not within counties, for example in the ocean, are associated to States based on BTS

assignments. These waterway weights are then evenly distributed among the counties within

these States that have navigable waterways. All shipping activity is summed at the county-level

and compared with national shipping activity to determine what portion of activity can be

attributed to individual counties. These proportions were used in disaggregating the national

CMV emission estimates to the county level.

b. Revised Port Allocation Method

Figures III-1 and III-2 present emission maps for CMV port and underway NOx emissions

created from the 1999 NEI Version 2.0 data. For underway emissions, Pechan believes that the

allocation procedure results in a reasonable distribution of county-level emissions. However, the

methodology to allocate port emissions results in all the emissions being assigned to a single

county. For example, Cabell County in West Virginia is assigned all emissions for Huntington

Port, but no emissions are allocated to Lawrence County in Ohio, the county on the opposite

river bank. 

Port areas encompass multiple States and counties and in some cases, multiple waterways.

Therefore, the emissions allocation process must incorporate all counties in the vicinity of the

port where activity is occurring. This is especially true for inland rivers where activity takes

place on both riverbanks and for 10 river miles or more outside the port city. The revised

methodology allocates port emissions based on a surrogate for port-related activity in each

county, rather than using a single county to define the port.
36

Figure 1.

VISTAS Region an

VISTAS Region and Surrounding States d Surrounding States

Underway NOx Emissions NOx Emissions(Tons per Year) 00 - 400 400 - 800 800 - 1,300

1,300 - 2,4002,400 - 3,680

E.H. Pechan & Associates, Inc.

Date: December 11, 2003.

Figure III-1. VISTAS Region and Surrounding States, Underway NOx Emission
37

Figure 2.

VISTAS Region and Surrounding States

VISTAS Region and Surrounding States

Port NOx Emissions NOx Emissions(Tons per Year) 00 - 3,000 3,000 - 7,000 7,000 - 13,000 13,000 - 26,000

26,000 - 67,000

E.H. Pechan & Associates, Inc.

Date: December 11, 2003.

Figure III-2. VISTAS Region and Surrounding States, Port NOx Emissions
38

The report, Waterborne Commerce of the United States, Calendar Year 1999 (USACE, 2000),

hereafter referred to as Waterborne Commerce, presents the cargo tonnage and number of vessel

trips in major waterways of the United States. The report defines port areas, which USACE uses

to develop the Top 150 Ports in the United States by amount of cargo tonnage. As discussed in

the previous section, the 1999 NEI allocates all the port emissions to these 150 ports based on the

cargo tonnage handled by the port. 

Pechan uses this allocation of emissions to each port area as the starting point of its revised

allocation process. Table III-4 presents the ports that are located in VISTAS and adjoining

States, which are part of the Top 150 Ports. 

Table III-4. Port Areas Located in VISTAS and Adjoining States 

Port State Port State

Mobile AL Pascagoula MS

Guntersville AL Vicksburg MS

Helena AR Biloxi MS

Port Everglades FL Greenville MS

Jacksonville FL Gulfport MS

Miami FL Wilmington NC

Port Canaveral FL Morehead City NC

Palm Beach FL Cincinnati OH

Panama City FL Pittsburgh PA

Pensacola FL Charleston SC

Tampa FL Georgetown SC

Port Manatee FL Memphis TN

Weedon Island FL Nashville TN

Savannah GA Chattanooga TN

Brunswick GA Norfolk Harbor VA

Mount Vernon IN Newport News VA

Louisville KY Hopewell VA

New Orleans LA Huntington WV

Baton Rouge LA

The next step was to develop a list of counties that make up the port area. Port area definitions

were obtained from Waterborne Commerce. Table III-6 presents the port definitions for the

VISTAS States and adjoining States. Using the port definitions by river mile, Pechan established

which counties are included in each port area. In many cases, these port areas encompass

multiple counties. For example, Pittsburgh is defined in Waterborne Commerce as:

Ohio River from Pittsburgh, PA to mile 40 (Pennsylvania/Ohio State Line); 

Allegheny River from Pittsburgh, PA to mile 72 (to head of project); 

Monongahela River from Pittsburgh, PA to mile 91 (to head of project). 
39

Therefore, the Port of Pittsburgh includes the following counties in Pennsylvania; Allegheny,

Westmoreland, Armstrong, Washington, Fayette, Greene, Beaver. This process was repeated for

all the port areas listed in Table III-4. 

The next step in allocating emissions is to develop a surrogate for the amount of CMV activity in

each county of the port area. Pechan assumed that the activity of vessels in each county is

related to the number of port facilities operating in a given county. Port facilities include

terminals, piers, wharves, and docks that are involved in all types of commercial activity and

support services. Pechan obtained the number of port facilities in each county from The Port

Series Reports (USACE, 2003). The USACE periodically surveys the commercial marine

industry to obtain information on port facilities and publishes it in The Port Series Reports. The

reports give the name, location, operations, and describe the physical and inter-modal

characteristics of the facilities. The data includes the location of the facility by river mile, State,

and county. 

For each port area, Pechan calculated the ratio between the number of port facilities in each

county to the total number of facilities in all counties that make up the port area. This ratio was

used to allocate emissions for each port area to the county-level. Table III-5 presents the

allocation ratios for each county in the port areas. Some port areas were still encompassed by

one county using the definition of the port from Waterborne Commerce. However, a number of

port areas include multiple counties. Note that New Orleans and Pittsburgh do not include any

counties in VISTAS States. 

Table III-5. List of VISTAS Ports and Ports of Adjoining States

Port State County Ratio Port State County Ratio Port State County Ratio

Port Everglades FL Broward 1.0 AR Phillips 0.7778 TN Hamilton 0.7692

Jacksonville FL Duval 1.0

Helena

MS Coahoma 0.2222 Chattanooga TN Marion 0.2308

Miami FL Miami-Dade 1.0 FL Charlotte 0.7500 VA Norfolk City 0.5568

Port Canaveral FL Brevard 1.0 Charlotte FL Lee 0.2500 VA Chesapeake

City 0.3068

Palm Beach FL Palm Beach 1.0 IN Vanderburgh 0.3182

Norfolk 

VA Portsmouth 0.1364

Panama City FL Bay 1.0 IN Posey 0.4773 VA Newport News 0.6500

Pensacola FL Escambia 1.0

Mount

Vernon 

KY Henderson 0.2045

Newport

News VA Hampton 0.3500

Tampa FL Hillborough 1.0 KY Jefferson 0.6596 VA Hopewell 0.5000

Port Manatee FL Manatee 1.0 Louisville IN Clark 0.3404 Hopewell VA Charles City 0.5000

Weedon Island FL Pinellas 1.0 LA St. Bernard 0.0858 PA Allegheny 0.5206

Savannah GA Chatham 1.0 LA Plaquemines 0.1231 PA Westmoreland 0.0412

Brunswick GA Glynn 1.0 LA Orleans 0.3284 PA Armstrong 0.0309

Pascagoula MS Jackson 1.0 LA Jefferson 0.4366 PA Washington 0.1340

Vicksburg MS Warren 1.0 LA St. Tammany 0.0224 PA Fayette 0.0412

Biloxi MS Harrison 1.0

New Orleans 

LA Tangipahoa 0.0037 PA Greene 0.0567

Greenville MS Washington 1.0 NC New Hanover 0.8974

Pittsburgh 

PA Beaver 0.1753

Gulfport MS Harrison 1.0 Wilmington NC Brunswick 0.1026 KY Greenup 0.0795

Morehead City NC Carteret 1.0 OH Hamilton 0.7931 KY Boyd 0.1023

Georgetown SC Georgetown 1.0 KY Kenton 0.0862 OH Gallia 0.1136

Nashville TN Davidson 1.0

Cincinnati 

KY Boone 0.1207 OH Lawrence 0.2273

Mobile AL Mobile 1.0 SC Charleston 0.7097 OH Scioto 0.1364

Guntersville AL Marshall 1.0 Charleston SC Berkeley 0.2903 WV Wayne 0.1136

TN Shelby 0.9123 WV Cabell 0.0795 Memphis AR Crittenden 0.0877

Huntington

WV Mason 0.1477
40

Pechan was directed to perform the reallocation for all VISTAS ports. Figure III-3 presents the

reallocation of port emissions in all States except Alabama. Alabama’s CMV data were

provided to EPA and already incorporated into the 1999 NEI Version 2, and Pechan did not have

access to the default 1999 NEI estimates for this State and category. Since State data take

precedence, the inventory prepared by Pechan reflects the incorporation of State data for those

areas that developed independent CMV emission estimates, including Virginia and Palm Beach

County, Florida. In addition, West Virginia provided their own county fractions to allocate

emissions for the Port of Huntington, using District-level data from the Army Corps of Engineers

on tonnage of freight shipped and received. West Virginia also requested that residual-fueled

CMV activity/emissions be zeroed out for their State. States providing their own data are

encouraged to review the allocations Pechan developed for their port areas, and to provide

further comment or direction as needed. 
41

Figure III-3. VISTAS Region and Surrounding States, Revised Port Emissions of N
42

Table III-6. Definition of Port Areas Obtained from Waterborne Commerce

(USACE, 2000)

VISTAS PORTS

MOBILE, AL

Entrance. bay and river channels, and channels into Chickasaw and Three Mile Creeks; Branch

Channels; Theodore Ship Channel.

GUNTERSVILLE, AL

Both banks of the Tennessee River at mile 358 to mile 363. 

JACKSONVILLE HARBOR, FL

Atlantic Ocean to the Florida East Coast Railway Bridge at Jacksonville, 26.8 miles. 

TAMPA, FL

Gulf of Mexico to and including the channels of upper Tampa Harbor, 49.8 miles; Channel to Port Tampa

and thence to Courtney Campbell Parkway, 17.5 miles; Natural channel leading from Port Tampa

Channel toward St. Petersburg, 1.8 miles; Alafia River Channel, 3.6 miles; Hillsborough River to City

Waterworks Dam, 10 miles; Channels in “Little Manatee River, Fl; Port Manatee, Fl Harbor.” 

MIAMI HARBOR, FL

Atlantic Ocean to inner end of turning basin at Miami, 6 miles; Meloy Channel and thence natural

channels along the easterly side of Biscayne Bay to Bakers Haulover Inlet, FL, about 11 miles; channel

from turning basin to mouth of Miami River, 1.1 miles; existing Florida East Coast Railway Channel,

Fishermans Channel from mouth of Miami River to Government Cut, 3.8 miles; and the channels reported

under “Miami River, FL.”

EVERGLADES HARBOR, COLLIER COUNTY, FL - No definition given

CANAVERAL HARBOR, FL

Entrance Channel (Atlantic Ocean) to Barrier Beach inner channel and Turning Basins, thence a Barge

canal through a lock in the perimeter dike and continuing to the Intracoastal Waterway, Jacksonville to

Miami. 

CHARLOTTE HARBOR, FL

Gulf of Mexico to Municipal Terminal at Punta Gorda, about 29.5 miles; waterfront on Gasparilla Island

from Port Boca Grande to Boca Grande, 4.5 miles; and Myakka River to El Jobean, 4 miles. 

PALM BEACH HARBOR, FL

Atlantic Ocean to Port of Palm Beach Terminals, 1.7 miles; Lake Worth from Riviera Bridge to Southern

Boulevard Bridge at West Palm Beach, 7.5 miles; and “Palm Beach, FL side channel and basin.” 

PORT MANATEE, FL

40 feet deep by 400 feet wide entrance channel and basin. The entrance channel extends approximately

3 miles in length from the turning basin to its intersection with Tampa Harbor main channel. Controlling

Depth: 40 feet in entrance channel and turning basin.

PANAMA CITY HARBOR, FL

Entrance channel, inside bay and Watson Bayou. Project Depth: Approach channel, 34 feet; across

Lands End, 32 feet; Watson Bayou, 10 feet.
43

Table III-6. Definition of Port Areas Obtained from Waterborne Commerce

(USACE, 2000)

PENSACOLA HARBOR, FL

Entrance channel and entire harbor, including Bayou Chico. 

Project Depth: entrance, 35 feet; Inner Harbor, 33 feet; Bayou Chico, 15 and 14 feet.

WEEDON ISLAND, FL – no definition

BRUNSWICK HARBOR, GA

From 32-foot contour in the ocean across the Barthrough St. Simon Sound, Brunswick River, and Turtle

River to the upper end of the Allied Chemical Company’s Wharf, formerly Atlantic Refining Company

Wharf, 20.4 miles; from Brunswick River through East River, to the upper end of the project in Academy

Creek, 2.7 miles; from St. Simon Sound through Back River to Mill Creek, the upper end of Back River

improvement, 2.9 miles; from Back River through Terry Creek to the Glynn Canning Company’s Wharf,

1.8 miles; a total distance of 27.8 miles. 

SAVANNAH HARBOR, GA

From the 40-foot contour in the ocean to the Continental Can Company Plant, 32.15 miles. 

LOUISVILLE, KY

Both banks of the Ohio River from mile 606 to mile 616

Controlling Depth: 9 feet. Project Depth: 9 feet at low water stages.

BILOXI HARBOR, MS

Mississippi Sound, Biloxi Bay, Back Bay, and land cut to Gulfport Lake. 

Project Depth: East entrance channel, Mississippi Sound to Gulfport Lake, 12 feet: West entrance

channel, Mississippi Sound to Biloxi Harbor, 10 feet; Ott Bayou, 12 feet.

GREENVILLE, MS

From Mississippi River mile 537 AHP left descending bank in an easterly direction, an entrance channel,

8,000 feet long and 250 feet wide transitioning into the harbor and port area 10,000 feet long and 500 feet

wide, then transitioning into Lake Ferguson, a channel 5,700 feet long and 250 feet wide. 

GULFPORT HARBOR, MS

Mississippi Sound Channel, Ship Island Pass Channel, and Small Craft Harbor about 4,300 feet long

west of the anchorage basin.

Project Depth: Mississippi Sound, 30 feet; Ship Island Pass, 32 feet; Small Craft Harbor, 8 feet.

PASCAGOULA HARBOR, MS

Lower 4 miles of Dog River and lower 6.8 miles of Pascagoula River, Mississippi Sound, Bayou Casotte,

and Horn Island Pass Channels. 

VICKSBURG, MS

From Mississippi River mile 437 AHP on left descending bank in a northerly direction, a channel 14,500

feet long by 150 feet wide in the Yazoo Diversion Canal, thence a dredged entrance channel 4,800 feet

long and 150 feet wide, transitioning into a 300-foot wide dredged slack water harbor and turning basin

10,700 feet long.

MOREHEAD CITY HARBOR, NC

Morehead City Harbor, NC. 
44

Table III-6. Definition of Port Areas Obtained from Waterborne Commerce

(USACE, 2000)

PORT OF WILMINGTON, NC 

(see also Wilmington Harbor NC for waterway data)

Both banks of the Cape Fear River extending from a point about 18 miles below the foot of Castle St. in

Wilmington to a point about 2 miles above the Railroad Bridge at Navassa, and both banks of Northeast

(Cape Fear) River from its mouth to a point about 1.67 miles above the Hilton Railroad Bridge.

CHARLESTON HARBOR, SC 

(Including Ashley River, Cooper River, Shem Creek And Shipyard River, SC)

Ocean to Goose Creek via Cooper River and Town Creek; to the Standard Wharf on Ashley River; to the

Mount Pleasant Memorial Highway Bridge on Shem Creek; to the Airco Alloys Wharf on Shipyard River;

Wando River to Cainhoy. 

GEORGETOWN HARBOR, SC (Winyah Bay)

Atlantic Ocean Entrance to Winyah Bay, SC, to and including turning basin in Sampit River at the City of

Georgetown, SC.

MEMPHIS, TN

Section Inlcuded: From mile 715.5 to mile 741.0 on Lower Mississippi River and includes Memphis

Harbor (McKellar Lake) and Wolf River Harbor,

Tennessee. Controlling Depth: 9 feet. Project Depth: 9 feet at low water stages.

PORT OF NASHVILLE, TN 

(included in traffic of Cumberland River, TN and KY)

Both banks of Cumberland River, mile 182 to mile 194

Controlling Depth: 9 feet. Project Depth: 9 feet at low water stages.

CHATTANOOGA, TN

Section Included: Both banks of the Tennessee River at mile 454 to 471. 

Controlling Depth: 9 feet. Project Depth: 9 feet at low water stages.

PORT OF RICHMOND, VA 

(Included in James River, VA Consolidated Report)

PORT OF NEWPORT NEWS, VA (Including Newport News Creek, VA)

Lower east shore of James River from mouth to 1.8 miles, and portion of north shore of Hampton Roads

covering approximately 15,000 linear feet of waterfront at Newport News; and Newport News Creek.

PORT OF HOPEWELL, VA (Included In James River VA Consolidated Report)

South side of James River, from City Point, at mouth of Appomattox River, 2 miles downstream to the

mouth of Baileys Creek.

Controlling Depth: 25 feet at mean low water. Project Depth: 35 feet, maintained to 25 feet.

NORFOLK HARBOR, VA

From 55-foot contour in Hampton Roads to Norfolk & Western (formerly Virginia) Railway Bridge Crossing

Southern Branch of Elizabeth River, 14.78 miles; thence upstream in Southern Branch, 4.61 miles. In

Eastern Branch, 2.54 miles upstream from the mouth of that branch; in Western Branch, 1.78 miles

upstream from the mouth of that branch; and 0.73 miles in Scotts Creek. 

HUNTINGTON, WV

Both banks of the Ohio River from mile 303 to mile 317

Controlling Depth: 9 feet. Project Depth: 9 feet at low water stages.
45

Table III-6. Definition of Port Areas Obtained from Waterborne Commerce

(USACE, 2000)

NON-VISTAS PORTS

HELENA, AR

Mile 659 through mile 663 on the Lower Mississippi River. 

The project provides for maintenance of an off-river harbor with dimensions of 9 feet deep and 450 feet

wide for a length of 3,200 feet.

MOUNT VERNON, IN

Section Included: Right Bank of Ohio River from mile 151 to mile 154. 

Controlling Depth: 9 feet. Project Depth: 9 feet at low water stages.

CINCINNATI, OH

Both banks of the Ohio River from mile 465 to mile 491. 

Controlling Depth: 9 feet. Project Depth: 9 feet at low water stages.

PORT OF PITTSBURGH, PA

Ohio River from Pittsburgh, PA to mile 40 (Pennsylvania/Ohio State Line); Allegheny River from

Pittsburgh, PA to mile 72(to head of project); Monongahela River from Pittsburgh, PA to mile 91(to head

of project). Includes Aliquippa-Rochester, Pittsburgh, Clairton-Elizabeth.

Controlling Depth: 9 feet. Project Depth: 9 feet.

PORT OF PLAQUEMINES, LA

Both banks of Mississippi River from mile 0 A.H.P. through mile 81.2 A.H.P

Controlling and Project Depths: 45 feet.

PORT OF BATON ROUGE, LA

Both banks of Mississippi River from mile 168.5 A.H.P. through mile 253 A.H.P; including the Baton

Rouge Barge Canal from a point on the east bank of the Mississippi River at mile 234.5 A.H.P., for a

distance of 5 miles. 

PORT OF NEW ORLEANS, LA

Both banks of the Mississippi River from mile 81.2 A.H.P. through mile 114.9 A.H.P.; Innerharbor

Navigation Canal, 5.5 miles; Mississippi River-Gulf Outlet from its junction with the Innerharbor Navigation

Canal to Bayou Bienvenue, 7 miles; and Harvey Canal, 5.5 miles.

PORT OF SOUTH LOUISIANA (LA)

Both banks of Mississippi River from mile 114.9 A.H.P. through mile 168.5 A.H.P. 

Controlling and Project Depths: 45 feet.
46

3. Projection Methods

Pechan then projected the revised 1999 inventory to 2002 using surrogate growth indicators. For

the aircraft category, 1999 and 2002 approach operations by airport and aircraft type were

compiled from the Federal Aviation Administration’s Air Traffic Activity Data System

(ATADS). The airport-level landing and takeoffs (LTOs) were assigned to counties and summed

for the county. For counties with aircraft emissions without a county match in ATADS, Stateaverage growth factors were calculated and applied. The county-level growth factors are not

presented in this report, but could be provided to VISTAS S/L/Ts if requested.

For locomotives, projected emissions were developed in two steps as described below. For 1999

to 2001, State-level vessel bunkering and rail fuel consumption was obtained from the Energy

Information Administration’s (EIA’s) Fuel Oil and Kerosene Sales. For 2001 to 2002, Pechan

applied national growth factors developed from fuel consumption projections in EIA’s Annual

Energy Outlook. Table III-7a lists the growth factors for locomotives that were applied to the

1999 emissions to first develop 2001 emissions. Table III-7b lists the growth factors used to

generate 2002 emissions. Locomotive emissions were not revised from the August 2003 draft

VISTAS 2002 inventory.

Table III-7a. Growth Factors for Railroad Distillate Fuel Oil Use

Rail Distillate Fuel Oil Sales

(Thousand Gallons)

FIPSST State

1999 2001

Growth Factor

(GF)

01 Alabama 42,137 55,777 1.3

12 Florida 127,269 107,084 0.8

13 Georgia 73,494 70,538 1.0

21 Kentucky 98,941 99,812 1.0

28 Mississippi 14,267 24,812 1.7

37 North Carolina 53,900 77,762 1.4

45 South Carolina 13,051 15,936 1.2

47 Tennessee 44,083 91,363 2.1

51 Virginia 32,202 61,154 1.9

54 West Virginia 9,160 8,787 1.0

Source: Department of Energy, Energy Information Administration Fuel Oil and Kerosene Sales 1999 & Fuel Oil and Kerosene

Sales 2001 Table 23. Adjusted Sales for Transportation Use: Distillate Fuel Oil and Residual Fuel Oil

(http://tonto.eia.doe.gov/FTPROOT/pertroleum/053599.pdf), (http://tonto.eia.doe.gov/FTPROOT/pertroleum/053501.pdf)
47

Table III-7b. 2002 National Rail Transportation Energy Use by Fuel Type

(Trillion BTU)

2001 2002 Growth Factor (GF)

Intercity Rail (Electric) 10.17 10.40 1.0226

Intercity Rail (Diesel) 16.60 16.88 1.0169

Transit Rail (Electric) 46.36 47.40 1.0224

INTERCITY/TRANSIT RAIL AVERAGE (SCC 2285002008) 1.0206

Commuter Rail (Electric) 16.13 16.49 1.0223

Commuter Rail (Diesel) 26.31 26.76 1.0171

COMMUTER RAIL AVERAGE (SCC 2285002009) 1.0197

Freight Rail (Distillate) 

(SCCs 2285002000, 2285002005, 2285002006,

2285002007, 2285002010)

512.81 492.32 0.9600

Source: Department of Energy, Energy Information Administration, Annual Energy Outlook 2003: Table 34. Transportation Sector

Energy Use by Fuel Type Within a Mode (http://www.eia.doe.gov/oiaf/aeo/supplement/sup_tran.pdf)

Since the CMV emissions were revised for the 1999 base year, these emissions were projected

using 2002 Fuel Oil and Kerosene Sales data, which became available in November 2003. Table

III-8 lists the growth factors for CMVs that were applied to 1999 emissions to generate 2002

emissions. The same regional growth factor that accounts for an average regional growth rate

was applied to CMV emissions for all VISTAS States. Because the State-level data represents

sales and not use, and CMV activity spans State borders, a regional growth factor was deemed

more appropriate. Pechan could make a similar adjustment for the locomotive growth factors,

which are also based on fuel sales for 1999 to 2001, if requested by VISTAS.
48

Table III-8. Growth Factors for Commercial Marine Vessel Distillate and Residual

Fuel Oil Use

Fuel Oil Sales

(Thousand Gallons)

Growth Factor (GF)

FIPSS

T

State

1999 2002

DISTILLATE

01 Alabama 67,455 73,400 1.1

12 Florida 139,809 143,577 1.0

13 Georgia 17,697 22,327 1.3

21 Kentucky 81,811 56,169 0.7

28 Mississippi 12,749 68,668 5.4

37 North Carolina 11,279 10,057 0.9

45 South Carolina 12,732 19,782 1.6

47 Tennessee 43,867 112,364 2.6

51 Virginia 29,444 28,235 1.0

54 West Virginia 54,560 46,981 0.9

Regional Distillate GF 471,403 581,560 1.2

RESIDUAL

01 Alabama 46,093 93,487 2.0

12 Florida 404,228 460,600 1.1

13 Georgia 40,117 79,191 2.0

21 Kentucky1 69 1.2

28 Mississippi 48,644 54,031 1.1

37 North Carolina 6,989 35,210 5.0

45 South Carolina 20,056 22,758 1.1

47 Tennessee1 124 1.2

51 Virginia 60,090 36,445 0.6

54 West Virginia 1.2

Regional Residual GF 626,217 781,915 1.2 1

 For Kentucky, Tennessee and West Virginia, Pechan summed the 1999 and 2002 CMV residual fuel oil use to develop a total

VISTAS State growth factor, which was then applied to the three States.

Source: Department of Energy, Energy Information Administration, Fuel Oil and Kerosene Sales 1999 & Fuel Oil and Kerosene

Sales 2002, Table 23. Adjusted Sales for Transportation Use: Distillate Fuel Oil and Residual Fuel Oil.

IV. ONROAD REFUELING METHODS

Emissions were separately calculated from onroad refueling, also known as Stage II emissions.

Since refueling is a category of evaporative rather than exhaust emissions, VOC is the only

criteria pollutant of concern for this category. This chapter discusses the controls modeled for

this emission category and the methods used to calculate these emissions. Refueling emissions

for onroad sources were updated in February 2004 to account for the VMT updates provided by

several States.

A. CONTROLS

Based on default information from the NEI as well as some information provided by VISTAS

agencies, portions of five of the VISTAS States have onroad Stage II refueling controls in place.

These States, along with the specific counties with onroad Stage II controls, are listed in

Table IV-1. This table also shows information about the Stage II control program in each State

including the year a Stage II program began, the number of years that the program was phased-in

over, and the control efficiency of the program in reducing VOC emissions from Stage II
49

refueling for the LDGV, LDGT, and HDGV vehicle categories. These are the inputs required for

modeling a Stage II control program using MOBILE6. States with Stage II programs should

review this information and provide any corrections for the next round of emissions modeling.

Table IV-1. Onroad Stage II Control Programs

State

Star

t

Year

Phase-In

Years

Control

Efficiency Counties

Florida

199

3

2 95% Broward, Miami-Dade, Palm Beach

Georgia

199

2

3 81% Cherokee, Clayton, Cobb, Coweta, DeKalb,

Douglas, Fayette, Forsyth, Fulton, Gwinnett, Henry,

Paulding, Rockdale

Kentucky

199

9

2 86% Boone, Campbell, Kenton

Kentucky

199

2

2 95% Jefferson

Tennesse

e

199

3

3 95% Davidson, Rutherford, Sumner, Williamson, Wilson

Virginia

199

3

2 95% Counties: Arlington, Chesterfield, Fairfax, Hanover,

Henrico, Loudoun, Prince William, Stafford

Independent Cities: Alexandria, Colonial Heights,

Fairfax, Falls Church, Hopewell, Manassas,

Manassas Park, Richmond

B. METHODS

A simplified set of MOBILE6.2 input files was created to simulate the onroad refueling emission

factors. These input files were simplified because several of the inputs used for calculating the

onroad exhaust and evaporative emission factors do not affect the refueling emission factors.

For example, the refueling emission factors are unaffected by vehicle speed or I/M program.

Thus, for each group of counties in a State with the same fuel parameters, temperature

parameters, fleet characteristics (registration distribution, diesel sales fractions), and Stage II

control program parameters, a MOBILE6.2 input file was created to model the onroad refueling

emission factors. As mentioned above, speed does not affect the refueling emission factors, so

each input file contained only 12 scenarios—one for each month of the year. Within each

scenario, the temperature and fuel parameters were varied, using the same temperature and fuel

data modeled in the onroad exhaust and evaporative MOBILE6.2 input files. Other fleet

characteristics, such as registration distributions and diesel sales fractions, were included in the

input files where applicable. The inputs shown in Table IV-1 were included for the input files

representing counties with Stage II control programs. The header section of the MOBILE6.2
50

input files was set up so that only refueling emission factors would be included in the tabular

output file.

After the MOBILE6.2 input files were generated, they were run through the MOBILE6.2 model

to obtain refueling VOC emission factors in the database table format. These emission factors

are produced for the 28 MOBILE6 vehicle types. The emission factors were then weighted using

the VMT fraction information included in the MOBILE6 output tables to obtain VOC refueling

emission factors for the 8 vehicle types included in the VISTAS VMT database. The VMT

fraction information contained in the MOBILE6 input files is based on the default MOBILE6

registration distributions, diesel sales fractions, and VMT fractions, or, when this information is

provided in the input files, based on area-specific fleet parameters. A database of emission

factors by month, county, and 8 vehicle types was then prepared. In calculating monthly onroad

refueling emissions, the VISTAS annual VMT data were temporally allocated by month in the

same manner as described in Chapter II for the onroad exhaust and evaporative emission

calculations. These VMT were then multiplied by the corresponding monthly emission factor (in

terms of grams per mile) to obtain refueling emissions from onroad vehicles. The monthly

emissions for each county were then summed to obtain annual refueling emissions. Also, since

refueling emissions are included in the area source inventory and are not distinguished by vehicle

type, all refueling emissions from onroad vehicles were summed for each county in the VISTAS

region. Summaries of the refueling emissions from onroad vehicles are presented in Chapter VI.

V. NONROAD REFUELING METHODS

The NONROAD model accounts for refueling emissions from nonroad equipment under two

separate components, vapor displacement and spillage. Vapor displacement emissions result

when new liquid fuel being added to a fuel tank displaces fuel vapors already present in the tank.

Spillage emissions result when fuel is spilled during the refueling process. 

Nonroad equipment may be fueled from a gasoline pump or a portable container. Refueling

nonroad equipment from a portable container results in different emissions for both spillage and

vapor displacement compared to refueling from a gasoline pump. In addition, the use of portable

containers also results in extra refueling events. Both spillage and displacement emissions will

also occur when the container is filled from a gasoline pump. However, due to lack of data, the

NONROAD2002 model does not attempt to quantify this set of refueling emissions. As such,

the NONROAD model refueling emissions associated with nonroad equipment being filled

directly at the gasoline pumps will be used to represent the nonroad Stage II emission

component. Stage II control factors listed in Table IV-1 were input in the county-specific

NONROAD model option files. Once the model runs were performed, Pechan extracted the

refueling and spillage emissions corresponding only to those engines (typically the larger

horsepower engines) within each SCC assumed to be refueled at the pump. The list of SCC and

horsepower ranges associated with pump versus container refueling is specified in the model

since different emission rates are assumed for these two types of refueling. 

Table V-1 presents draft annual Stage II VOC emission estimates by State. These emissions

were combined with the onroad vehicle Stage II estimates described in Section IV of this report.
51
52

Table V-1. 2002 Draft Stage II Refueling Emissions by State

FIPSST NAME VOC Emissions, tpy

01 Alabama 167.25

12 Florida 842.60

13 Georgia 209.01

21 Kentucky 112.65

28 Mississippi 147.18

37 North Carolina 298.49

45 Tennessee 197.81

47 South Carolina 155.33

51 Virginia 174.70

54 West Virginia 39.33

VI. SUMMARY OF RESULTS

This chapter presents the emission results from the February 2004 draft version of the 2002

mobile source emissions inventory for the VISTAS region. These emissions result from the data

and procedures described in the preceding chapters of this report. 

A. ONROAD RESULTS

Table VI-1 summarizes the latest 2002 VISTAS onroad emissions inventory by State. This table

also summarizes the total VMT for each State. Tables VI-2 and VI-3 are provided here for the

purpose of comparing this inventory with another existing onroad inventory. The emissions

shown in Table VI-2 are taken from Version 2 of EPA’s 1999 NEI. Table VI-3 then shows the

percentage change from the 1999 NEI to the 2002 draft VISTAS inventory. If the two

inventories had been developed using comparable data, one would generally expect to see

reductions in the onroad emissions from 1999 to 2002 due to fleet turnover resulting in the

replacement of older, dirtier vehicles with vehicles meeting more stringent emission standards.

However, this reduction in per-vehicle emissions also needs to overcome increases in VMT for

the overall emissions to decrease. All of the VISTAS States show increases in VMT from 1999

to 2002, except North Carolina. This decrease in VMT needs to be further investigated by the

State agency. States that were modeled with significant State or locally supplied inputs in the

VISTAS modeling, such as Virginia and Georgia, would be expected to have more significant

differences from the NEI data than States with no State-supplied information other than VMT.

Some of the State inputs that cause significant deviations from the NEI estimates are registration

distributions, VMT mixes by vehicle type, and speeds by road type. In addition, some of the

pollutants are more affected by these inputs, while others (such as NH3) are minimally affected

by these inputs. The 2002 VISTAS onroad emissions will continue to undergo review. Any

comments or questions on these emissions by the State or local agencies will be investigated as

part of this review.
53

Table VI-1. 2002 VISTAS Onroad Emissions and VMT by State 

(February 2004 Version)

2002 Annual Emissions (tons per year) 2002 Annual VMT

State VOC NOx CO SO2 PM10 PM2.5 NH3 (million miles)

Alabama 99,650 154,908 1,275,969 6,515 4,344 3,231 5,619 55,723

Florida 457,309 463,419 4,678,471 19,739 12,666 9,232 18,240 178,681

Georgia 215,035 311,125 2,601,785 11,487 8,038 5,942 10,612 106,785

Kentucky 79,110 164,231 1,196,211 5,718 4,083 3,048 5,103 51,020

Mississippi 68,508 107,047 845,990 4,354 3,152 2,399 3,603 36,278

North Carolina 147,977 278,265 2,116,829 9,953 6,374 4,741 7,868 80,166

South Carolina 92,491 136,569 1,192,894 5,647 3,825 2,867 4,719 47,074

Tennessee 126,959 255,090 1,785,136 8,115 5,445 4,059 6,855 68,316

Virginia 115,044 182,513 1,858,629 6,110 4,413 3,032 7,937 76,566

West Virginia 34,197 57,941 512,592 2,361 1,550 1,155 1,947 19,544

VISTAS Total 1,436,279 2,111,108 18,064,506 79,999 53,890 39,705 72,504 720,153

Table VI-2. 1999 NEI Version 2 Onroad Emissions and VMT by State

1999 Annual Emissions (tons per year) 1999 Annual VMT

State VOC NOx CO SO2 PM10 PM2.5 NH3 (million miles)

Alabama 121,201 163,024 1,412,343 6,280 4,712 3,599 5,249 52,914

Florida 328,412 424,969 3,379,563 16,581 12,259 9,318 14,162 141,903

Georgia 207,562 313,568 2,526,592 12,028 9,263 7,139 9,787 98,859

Kentucky 97,286 162,160 1,225,414 6,006 4,772 3,715 4,703 47,816

Mississippi 74,579 126,344 830,477 4,478 3,908 3,106 3,406 34,955

North Carolina 187,346 285,380 2,252,671 10,829 8,462 6,552 8,663 87,759

South Carolina 98,010 153,346 1,207,336 5,616 4,515 3,527 4,330 44,146

Tennessee 138,629 211,133 1,697,778 7,876 6,108 4,716 6,392 64,570

Virginia 150,528 238,515 1,861,417 8,972 6,892 5,307 7,320 73,904

West Virginia 40,060 68,580 539,578 2,471 2,023 1,589 1,859 19,033

VISTAS Total 1,443,613 2,147,019 16,933,170 81,137 62,913 48,567 65,871 665,859
54

Table VI-3. Change in Onroad Emissions and VMT from 1999 NEI Version 2 to

VISTAS 2002 Inventory (February 2004 Version)

Change from 1999 NEI V2 to 2002 VISTAS Draft Inventory

State VOC NOx CO SO2 PM10 PM2.5 NH3 VMT

Alabama -18% -5% -10% 4% -8% -10% 7% 5%

Florida 39% 9% 38% 19% 3% -1% 29% 26%

Georgia 4% -1% 3% -4% -13% -17% 8% 8%

Kentucky -19% 1% -2% -5% -14% -18% 9% 7%

Mississippi -8% -15% 2% -3% -19% -23% 6% 4%

North Carolina -21% -2% -6% -8% -25% -28% -9% -9%

South Carolina -6% -11% -1% 1% -15% -19% 9% 7%

Tennessee -8% 21% 5% 3% -11% -14% 7% 6%

Virginia -24% -23% 0% -32% -36% -43% 8% 4%

West Virginia -15% -16% -5% -4% -23% -27% 5% 3%

VISTAS Total -1% -2% 7% -1% -14% -18% 10% 8%

Table VI-4 presents the latest 2002 VISTAS onroad refueling emission estimates by State.

These refueling emissions are NOT included in the emissions shown in Tables VI-1 through VI3.

Table VI-4. 2002 VISTAS Annual Onroad Refueling Emissions

State

2002 Annual Onroad VOC Refueling Emissions

(tons per year)

Alabama 8,408

Florida 28,367

Georgia 12,329

Kentucky 6,885

Mississippi 6,057

North Carolina 15,320

South Carolina 8,926

Tennessee 9,901

Virginia 8,657

West Virginia 3,383

VISTAS Total 108,233

B. NONROAD RESULTS

Table VI-5 provides a summary of draft 2002 nonroad sector annual emissions by State,

including Stage II refueling emission estimates. Table VI-6 provides a summary of the draft

2002 NONROAD model emission estimates by State, and compares the values to 2001

NONROAD model NEI Version 2 estimates by showing the percent difference. A similar

comparison is shown in Table VI-7 for other nonroad emission estimates compared to the 1999

NEI Version 2.
55

For the NONROAD model categories, SO2, PM10, PM2.5, and NH3 decrease consistently across

all States. SO2 emissions decrease due in part to a lower diesel fuel sulfur content input for the

NONROAD model runs, which also contributes to decreases in particulate emissions. The

decrease in NH3 is due primarily to corrections made to compresses natural gas (CNG) engine

NH3 emissions, which involved zeroing out the estimates. The 1999 NEI erroneously applied

emission factors on a grams per gallon basis to CNG fuel consumption. Although reported as

uncompressed gallons in the NONROAD model, the CNG fuel consumption estimates represent

a gaseous, not liquid, volume. Based on OTAQ’s recommendations, CNG NH3 emissions are

now reported as zero. CO and NOx show little change for all States, and changes in VOC vary

by State and are dependent on the contribution of specific equipment categories (detail not

shown).

For other nonroad categories, the increase in PM10 and PM2.5 is due to the addition of

commercial aircraft PM emissions. Commercial aircraft PM10 and PM2.5 emissions were zero in

the 1999 NEI; hence, the large percent increase. To gap fill this portion of the inventory, Pechan

calculated and applied an average air taxi PM/NOx emission ratio to commercial aircraft NOx

emissions. States with a higher proportion of commercial aircraft show significant PM increases

(e.g., FL, TN, VA). In addition, NOx emissions decrease due to new State data for other nonroad

from AL and VA. 

Table VI-5. Summary of Draft 2002 Nonroad Sector Annual Emissions by State,

tons per year

FIPSS

T

STATE VOC NOX CO PM10-

PRI

PM25-

PRI SO2 NH3

01 Alabama 46,788 64,367 373,634 5,504 4,895 7,529 32

12 Florida

211,006 153,396

1,765,53

9 61,426 45,849 17,453 109

13 Georgia 66,712 87,053 712,159 10,411 8,666 7,914 55

21 Kentucky 35,537 100,989 294,929 8,538 7,249 13,771 28

28 Mississippi 33,443 90,190 217,407 5,795 5,194 11,537 23

37 North Carolina 75,020 81,264 742,822 12,814 10,379 7,281 62

45 South Carolina 43,231 46,518 375,469 4,115 3,678 4,465 29

47 Tennessee 52,333 118,690 461,976 14,727 11,692 12,478 41

51 Virginia 61,655 69,668 614,958 21,580 16,497 11,068 44

54 West Virginia 15,497 36,613 120,029 2,293 2,034 2,388 10
56

Table VI-6. Summary of Draft 2002 NONROAD Model

Emission Estimates by State 

2002 DRAFT VISTAS NONROAD Model Inventory, tpy

FIPSS

T STATE

VOC_AN

N

NOX_AN

N CO_ANN

PM10_AN

N

PM25_AN

N SO2_ANN

NH3_AN

N

01 Alabama 44,501.18 28,635.48

365,161.1

2 3,306.84 3,044.48 2,729.32 31.92

12 Florida

205,489.6

6 86,654.40

1,730,125.

77 12,890.06 11,862.13 9,113.26 109.02

13 Georgia 65,054.02 51,452.93

705,292.7

5 5,493.33 5,057.34 5,025.11 54.97

21 Kentucky 32,836.91 28,253.72

283,488.5

3 3,152.29 2,901.82 2,777.69 28.00

28 Mississippi 31,097.14 23,549.89

207,824.2

3 2,761.65 2,542.05 2,375.53 23.37

37

North

Carolina 73,610.93 58,667.62

734,496.8

5 6,095.96 5,613.11 5,442.35 62.06

45

South

Carolina 41,652.41 26,212.76

366,737.1

6 3,028.92 2,788.66 2,461.79 29.29

47 Tennessee 48,626.66 39,833.95

446,461.4

3 4,240.53 3,904.21 3,810.11 41.22

51 Virginia 56,973.85 40,914.48

594,020.1

3 4,739.47 4,362.61 4,103.01 44.22

54

West

Virginia 14,498.68 9,502.33

115,652.4

9 1,038.29 955.70 980.17 10.31

2001 NONROAD Model NEI Version 2, tpy

FIPSS

T STATE

VOC_AN

N

NOX_AN

N CO_ANN

PM10_AN

N

PM25_AN

N

SOX_AN

N

NH3_AN

N

01 Alabama 43,602.83 28,786.95

360,439.3

6 3,422.60 3,150.91 3,110.79 581.69

12 Florida

188,868.9

6 86,835.32

1,713,539.

62 13,243.04 12,186.78 10,456.05 1,305.25

13 Georgia 63,927.85 51,521.66

698,868.7

7 5,678.55 5,227.63 5,749.47 989.31

21 Kentucky 31,662.34 28,350.32

279,283.7

9 3,274.35 3,014.06 3,127.88 463.74

28 Mississippi 29,037.96 23,671.70

205,664.6

4 2,877.28 2,648.40 2,668.55 359.21

37

North

Carolina 69,671.36 58,742.13

724,908.4

6 6,300.02 5,800.72 6,196.92 1,223.82

45 South 39,310.79 26,304.57 3,130.17 2,881.75 2,817.02 507.81
57

Carolina 363,112.0

1

47 Tennessee 47,193.97 39,916.38

440,915.7

6 4,395.90 4,047.06 4,337.42 749.51

51 Virginia 55,459.80 41,082.63

585,850.5

8 4,887.90 4,499.09 4,677.52 627.60

54

West

Virginia 13,912.53 9,568.82

113,766.3

8 1,076.32 990.67 1,113.21 179.75

Percent Difference

FIPSS

T STATE

VOC_AN

N

NOX_AN

N CO_ANN

PM10_AN

N

PM25_AN

N

SOX_AN

N

NH3_AN

N

01 Alabama 2.06% -0.53% 1.31% -3.38% -3.38% -12.26% -94.51%

12 Florida 8.80% -0.21% 0.97% -2.67% -2.66% -12.84% -91.65%

13 Georgia 1.76% -0.13% 0.92% -3.26% -3.26% -12.60% -94.44%

21 Kentucky 3.71% -0.34% 1.51% -3.73% -3.72% -11.20% -93.96%

28 Mississippi 7.09% -0.51% 1.05% -4.02% -4.02% -10.98% -93.50%

37

North

Carolina 5.65% -0.13% 1.32% -3.24% -3.23% -12.18% -94.93%

45

South

Carolina 5.96% -0.35% 1.00% -3.23% -3.23% -12.61% -94.23%

47 Tennessee 3.04% -0.21% 1.26% -3.53% -3.53% -12.16% -94.50%

51 Virginia 2.73% -0.41% 1.39% -3.04% -3.03% -12.28% -92.95%

54

West

Virginia 4.21% -0.69% 1.66% -3.53% -3.53% -11.95% -94.26%
58

Table VI-7. Summary of Draft 2002 Other Nonroad* Emission Estimates by State

2002 DRAFT VISTAS Other Nonroad Inventory, tpy

FIPSST STATE VOC_ANN NOX_ANN CO_ANN PM10_ANN PM25_ANN SO2_ANN

01 Alabama 2,286.81 35,731.80 8,473.33 2,196.87 1,850.82 4,799.75

12 Florida 5,516.71 66,741.52 35,413.13 48,536.33 33,987.28 8,340.05

13 Georgia 1,657.99 35,599.76 6,865.94 4,917.40 3,609.14 2,889.06

21 Kentucky 2,699.92 72,735.57 11,440.23 5,385.61 4,346.83 10,992.91

28 Mississippi 2,345.96 66,640.48 9,582.89 3,033.69 2,652.14 9,161.66

37 North Carolina 1,409.01 22,596.53 8,325.56 6,718.49 4,766.12 1,838.68

45 South Carolina 1,578.34 20,304.80 8,732.26 1,086.01 889.24 2,002.78

47 Tennessee 3,706.17 78,855.60 15,514.17 10,486.01 7,787.92 8,667.84

51 Virginia 4,681.39 28,753.43 20,938.22 16,840.30 12,134.84 6,965.04

54 West Virginia 998.41 27,110.49 4,376.64 1,254.86 1,077.93 1,408.05

1999 Other Nonroad NEI Version 2, tpy

FIPSST STATE VOC_ANN NOX_ANN CO_ANN PM10_ANN PM25_ANN SO2_ANN

01 Alabama 7,309.83 152,338.93 25,075.50 1,315.93 1,176.15 3,854.54

12 Florida 3,945.18 56,197.72 25,350.10 2,110.74 1,881.95 6,878.28

13 Georgia 2,594.07 39,245.14 12,198.09 1,072.08 953.43 3,070.41

21 Kentucky 2,676.93 62,930.31 12,388.06 2,370.31 2,153.93 8,965.67

28 Mississippi 1,755.99 48,927.22 8,072.51 1,917.16 1,747.89 7,051.91

37 North Carolina 1,447.95 17,999.44 8,739.21 540.09 470.85 1,508.40

45 South Carolina 2,470.03 18,034.10 13,291.47 561.99 503.60 1,858.19

47 Tennessee 2,426.97 51,133.47 11,127.02 1,786.06 1,616.72 6,266.91

51 Virginia 2,682.78 51,592.64 13,083.30 1,632.38 1,462.82 4,769.97

54 West Virginia 1,133.03 30,991.75 4,858.71 1,151.55 1,048.38 4,097.15

Percent Difference

FIPSST STATE VOC_ANN NOX_ANN CO_ANN PM10_ANN PM25_ANN SO2_ANN

01 Alabama -69% -77% -66% 67% 57% 25%

12 Florida 40% 19% 40% 2199% 1706% 21%

13 Georgia -36% -9% -44% 359% 279% -6%

21 Kentucky 1% 16% -8% 127% 102% 23%

28 Mississippi 34% 36% 19% 58% 52% 30%

37 North Carolina -3% 26% -5% 1144% 912% 22%

45 South Carolina -36% 13% -34% 93% 77% 8%

47 Tennessee 53% 54% 39% 487% 382% 38%

51 Virginia 74% -44% 60% 932% 730% 46%

54 West Virginia -12% -13% -10% 9% 3% -66%

*Includes emissions from aircraft, commercial marine and locomotive SCCs
59

VII. OBSERVATIONS AND RECOMMENDATIONS FOR

IMPROVEMENT

This chapter lists several areas where the onroad and nonroad emission inventories could be

improved. Some of these improvements require a long lead-time for the States and would not

likely be available for the final 2002 VISTAS modeling, but could improve future State and

regional inventory efforts.

A. ONROAD SECTOR IMPROVEMENTS

In the onroad sector, significant improvements have been made to the inventory due to the State

and local agencies providing 2002 VMT data by county and roadway type. For this February

2004 version of the VISTAS onroad inventory, only the Virginia VMT were projected by

Pechan. It is anticipated that this States will be able to provide 2002 VMT data for use in the

next revision of the inventory.

Local registration distribution data were provided by fewer than half of the VISTAS States. In

many cases, registration data can be obtained from State Departments of Motor Vehicles. States

that do not already do so should request a download of the data summarizing registrations by

model year and vehicle class from their appropriate motor vehicle agency. Although it is

probably too late in many cases to obtain 2002 data, 2003 registration data could be used with

some adjustments in developing the 2002 emission inventories. Registration data will become

even more important as VISTAS prepares to project a 2018 onroad emission inventory, since the

2018 projections will be affected by the number of vehicles that are subject to the Tier 2

emission standards and the new heavy duty vehicle standards. The registration distributions

directly determine the proportion of vehicles subject to these new emission standards.

A relatively small amount of data was obtained regarding the distribution of VMT by season or

month. Many State Departments of Transportation collect data that could be used to better

distribute VMT by season or month. States should check to see what is available. These

distributions will affect the episodic modeling that will be conducted by VISTAS. Pechan is

currently performing a VMT scoping study for VISTAS to determine what data are available for

better allocating VMT and emissions by month, day, and hour. These temporal improvements

are expected to be incorporated into the next update of the VISTAS onroad emission inventory.

Due to the direct relationship between the VMT mix by vehicle type and the overall emissions,

States should investigate potential sources of information for this data to replace the default data

used here in most States. 

EPA is currently in the process of preparing guidance on estimating emissions from heavy duty

vehicles during long-term idling (sometimes referred to as hotelling). While these emissions are

theoretically included in the MOBILE6 HDDV emission factors, they are not currently

accounted for in the appropriate locations. For example, these emissions would typically occur

at rest stops, trucking centers, and warehouse and distribution centers. With the current

modeling, these emissions are spread over all counties, based on the VMT traveled by HDDVs in

each county. If significant sources of truck idling emissions occur in or near Class I areas, the
60

current modeling may be underestimating the effect of these emissions. If States are able to

obtain data on the locations and utilization of truck rest stops, some of this emissions effect could

be more appropriately accounted for in future versions of VISTAS modeling.

B. NONROAD SECTOR IMPROVEMENTS

NH3 emissions for aircraft, commercial marine and locomotives are still reported as zero. As a

result of recent communications with OTAQ, Pechan would suggest applying the updated

nonroad diesel NH3 emission factors used for the NONROAD model categories to activity data

for commercial marine vessels and locomotives. To develop ammonia from commercial marine

vessels and locomotives, Pechan would need to obtain or compile the county-level fuel

consumption estimates used as the basis for 1999 emissions for these categories to use as the

activity data for calculating updated NH3 emissions. The presence of State or local data in the

1999 NEI does not allow for this to be determined easily by backing out the reported emission

factors, and in some cases (e.g., diesel commercial marine), actual emissions (instead of activity)

were obtained at a national level and allocated to counties (EPA, 2002). Alternatively, Pechan

could use county level fuel consumption estimates developed for these categories for 2000 or

2001. These activity data were used by Pechan to estimate dioxin/furan emission estimates for

the 2000 and 2001 NEI. Pechan could normalize the 2000 or 2001 county distribution to

national level fuel consumption estimates for 1999. Due to the characteristics of aircraft jet and

piston engines, Pechan does not recommend estimating aircraft NH3 emissions using the

available NH3 emission factors. 

VIII. REFERENCES

EPA, 1989: “Procedures for Emission Inventory Preparation, Volume IV: Mobile Sources.”

U.S. Environmental Protection Agency, Office of Mobile Sources and Office of Air Quality

Planning and Standards, EPA 450/4-81-026d (Revised). July 1989.

EPA, 2002. “Documentation for Aircraft, Commercial Marine Vessel, Locomotive, and Other

Nonroad Components of the National Emissions Inventory,” prepared by Eastern

Research Group, Morrisville, NC for the U.S. Environmental Protection Agency, Office

of Air Quality Planning and Standards, Research Triangle Park, NC. September 30,

2002. 

Harvey, 1983. Craig Harvey, et al. “A Study of the Potential Impact of Some Unregulated

Motor Vehicle Emissions.,” SAE Paper 830987. June 1983. 

Harvey, 2003. C. Harvey, U.S. Environmental Protection Agency, Office of Transportation and

Air Quality, e-mail entitled “NH3 Emission Updates,” sent to K. Thesing, E.H. Pechan &

Associates, Inc. June 30, 2003. 

USACE, 2000: Waterborne Commerce of the United States, Calendar Year 1999, IWR-WCUS99-2 U.S. Army Corps of Engineers. 2000.
61

USACE, 2003: U.S. Waterways Data, Port and Waterway Facilities, [Data file]. Accessed from

U.S. Army Corps of Engineers, http://www.iwr.usace.army.mil/ndc/data/datapwd.htm on

December 12, 2003.