The Atlanta Eight-Hour Ozone Attainment Demonstration 

Appendix U 

Mobile Source Emissions Modeling 

for Atlanta 

Ozone Attainment Demonstration 

Motor Vehicle Emissions Budgets
Overview 

The Georgia Environmental Protection Division (EPD) worked with the Atlanta Regional 

Commission (ARC) to develop mobile1 source emissions inventories for the purpose of 

establishing motor vehicle emission budgets (MVEB) for the Atlanta 8-Hour Ozone 

Attainment State Implementation Plan (SIP) revision, hereinafter called the Ozone 

Attainment Plan. These inventories reflect the most recent planning assumptions and 

emission factor model2 available, and the use of updated travel demand and emissions 

calculation models. The ARC's travel demand and emissions estimation modeling 

process was employed to estimate on-road mobile source emissions. The mobile source 

emission inventories for the Ozone Attainment Plan MVEB were calculated in a manner 

consistent with federal regulations for performing regional emissions analyses used in 

transportation conformity determinations. The alignment of methodologies for mobile 

source inventories and transportation conformity emissions analyses prevents spurious 

differences between motor vehicle emission budgets (i.e., the SIP's estimate of future 

mobile source emissions) and transportation conformity analyses that must conform to 

those budgets. 

The 20-county Atlanta ozone nonattainment area was originally classified as a "marginal" 

nonattainment area. With an attainment year of 2007, marginal 8-hour ozone areas were 

required to attain the National Ambient Air Quality Standard (NAAQS) by the 2006 

ozone season. Because monitoring data from the 2006 ozone season indicated that 

Atlanta had not attained the NAAQS, the area was reclassified3

 to "moderate," with an 

attainment date no later than June 15, 2010. 

 

For use in making transportation conformity determinations for the Atlanta 8-hour ozone 

nonattainment area, the Ozone Attainment Plan will establish MVEB for the year 2009. 

In contrast with previous EPA guidance and with Georgia’s approved Post-1996 9% Plan 

and Post-1999 ROP4 Plan, this Ozone Attainment Plan does not rely on any emission 

reductions outside the nonattainment area. As determined through interagency 

consultation, the emission factors used reflect an assumption that ethanol-blend gasoline 

will have 100 percent market share in summer 2009. Modeling assumptions were 

distributed to the interagency consultation partners on October 28, 2008. 

Mobile Source Emissions Inventory 

In order to develop the Ozone Attainment Plan MVEB, 2009 budget year VOC and NOx 

emission inventories for the 20-county eight-hour ozone nonattainment area were 

 

1

 The term "mobile" is used to describe emissions from on-road motor vehicles. 

2

 MOBILE6.2.03 (http://www.epa.gov/otaq/m6.htm#m60) 3

 73 Federal Register 12013, March 6, 2008 

4

 The terminology EPA uses for progress towards attainment has been codified at 40 CFR Part 51.900: 

"reasonable further progress" (RFP) is used for the 8-hour ozone NAAQS, "rate of progress" (ROP) is used 

for the former 1-hour NAAQS. 

U-1 
produced. Reference Figure U-1 for a map of the nonattainment area. These 2009 motor 

vehicle emissions inventories reflect the latest travel demand and emissions modeling 

processes used for transportation conformity purposes by the ARC, and latest available 

planning assumptions as documented in Appendix U, Exhibits 3 and 4. 

U-2 
Figure U-1 

Atlanta Ozone Nonattainment Area 

U-3 
Emissions Inventory - 20 County Eight-Hour Ozone 

Nonattainment Area

In support of Ozone Attainment Plan MVEB development, the ARC produced 

nonattainment area mobile emissions inventories for the 2009 Attainment budget year. 

The travel demand and emissions modeling process and the planning assumptions used 

for the Ozone Attainment Plan are summarized below and in Appendix U, Exhibits 3 and 

4. 

The ARC currently maintains a travel model for 20 counties that correspond to the eighthour ozone nonattainment area. The ARC travel demand model is designed to, at 

minimum, represent the state of the practice in travel demand modeling and to meet all 

modeling requirements specified in the federal Transportation Conformity Rule (40 CFR 

Parts 51 and 93). The Transportation Conformity Rule establishes a regulatory 

requirement that includes minimum specifications for travel models used to forecast 

vehicle activity for regional emission analyses in certain nonattainment and maintenance 

areas. These minimum specifications (see 40 CFR Section 93.122(b)) apply to 

metropolitan planning areas with an urbanized area population over 200,000 that are also 

serious, severe, or extreme ozone; or serious carbon monoxide; nonattainment areas. 

Atlanta met those conditions under the one-hour ozone standard, for which the area had 

been classified as serious (effective January 6, 1992) and severe (effective January 1, 

2004), before being redesignated to attainment of the one-hour ozone standard (effective 

June 14, 2005). Because travel model VMT are adjusted to count-based estimates before 

being used for emissions calculations, the biggest remaining difference between networkmodel-based activity and activity estimated using other "appropriate methods [40 CFR 

Section 93.122(d)]" is the level of speed averaging. Despite the fact that Atlanta's current 

ozone nonattainment classification (moderate) would not otherwise subject it to the 

modeling requirements of 93.122(b), EPA regulations5

 require the continued use of 

activity from network-based travel models for transportation conformity emissions 

estimates in Georgia. 

A full consultation process, including national peer review, and the ARC strategic travel 

demand model enhancement program guide all modifications to the travel demand model. 

As a result, all elements of the travel demand model are designed to support all technical 

and policy decisions that are required in developing a comprehensive, multimodal 

transportation plan and program in accordance with the Safe, Accountable, Flexible, 

Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU), the 1990 

Clean Air Act Amendments, and the Transportation Conformity Rule. 

The previously most recent emissions inventories developed using ARC’s travel demand 

and emissions modeling process were completed as part of the transportation conformity 

analysis for ARC's Envision6 2030 Regional Transportation Plan (RTP) and associated 

 

5

 "In all areas not otherwise subject to paragraph (b) of this section, regional emissions analyses must use 

those procedures described in paragraph (b) of this section if the use of those procedures has been the 

previous practice of the MPO [40 CFR Section 93.122(d)]." 

U-4 
FY 2008-2013 Transportation Improvement Program (TIP); and the Gainesville-Hall 

MPO's 2030 RTP and associated 2008-2013 TIP; approved by the U.S. Department of 

Transportation (USDOT), in consultation with the EPA, on October 10, 2007. A number 

of enhancements to the travel demand model, described below, are reflected in those 

inventories and in the inventories developed for the Ozone Attainment Plan MVEB. 

Some changes to the travel model were a result of a significant model recalibration 

initiated after the expansion of the modeling platform from a 13-county to a 20-county 

geography. Enhancements include updated population and employment estimates that 

reflect the expanded modeling platform, as well as structural changes within the model 

needed to recalibrate to its base year, 2000, including the following: 

• Mode choice model updated to improve performance of suburban intra-county trips, 

• Attraction share model incorporated into four-step modeling process, and 

• New commercial vehicle and truck model developed to improve traffic assignment 

for both passenger vehicles and truck traffic. 

The ARC’s emissions model has also been updated to reflect all travel model 

improvements resulting from expansion to the 20-county geography and new 2000 base 

year recalibration. The emissions modeling procedure requires input of travel model 

networks for the specific scenario year, in this case 2009. External files that specify 

VMT adjustment factors and MOBILE6 emission factors are also required. Changes to 

these networks and external files include the following: 

• Network files reflect expansion of model system to cover the 20-county eight-hour 

ozone nonattainment area (2009 travel model network year), 

• Highway Performance Monitoring System (HPMS) adjustment factors6 updated to 

reflect the latest 20-county travel model recalibration for year 2000, 

• Updated seasonal adjustment factors, and 

• Latest MOBILE6 emission factors. 

Travel Model Networks

To prepare the mobile source emissions inventories for establishing the Ozone 

Attainment Plan MVEB, it was necessary to create a transportation network for 2009. 

The year 2009 network needed for the 2009 Attainment Plan MVEB inventories was 

derived from the 2010 travel model network. Year 2009 population and employment 

data were interpolated from the latest regional control demographic forecasts documented 

in Appendix U, Exhibit 4. 

A small portion of the Atlanta Urbanized Area extends into Hall County. In February 

2003, the Gainesville-Hall MPO (GHMPO) was designated for the Gainesville Urbanized 

Area; the planning boundary for the GHMPO covers Hall County in its entirety. Hall 

County is included in Atlanta's ozone nonattainment area. The ARC, by agreement with 

 

6

 The VMT from the travel demand model are adjusted based on the VMT estimates that Georgia DOT 

develops for HPMS. 

U-5 
the GHMPO, performs the emissions modeling for Hall County. Travel model networks 

reflect the project listing as approved: 

• in ARC's Envision6 2030 RTP and 2008-2013 TIP; adopted by the ARC Board 

September 26, 2007; and received a positive conformity determination from USDOT 

October 10, 2007; and 

• in the GHMPO's 2030 RTP and 2008-2013 TIP; adopted by the GHMPO Board 

August 14, 2007; and received a positive conformity determination from USDOT 

October 10, 2007 

Project coding for network year 2009 (based on 2010 network) was reviewed by state and 

local project sponsors in March and April 2007 as part of the development of the 

Envision6 and GHMPO 2030 RTPs and FY 2008-2013 TIPs. The 2009 network was run 

through a full travel model assignment procedure, based on the recalibrated model 

stream, to produce the VMT and speeds for the mobile source emission inventories. 

VMT Adjustment Factors

Traffic volumes produced by the travel model are adjusted within the emissions modeling 

process by applying a VMT adjustment factor, which is a combination of HPMS 

adjustment factors, used to reconcile travel model VMT to HPMS VMT estimates,7 and 

seasonal adjustment factors used to convert the average annual daily traffic produced by 

the travel model to average summer-time daily traffic for the purposes of ozone precursor 

emissions modeling8. 

EPA requires9 that reasonable methods be used to estimate VMT on off-network (offmodel) roadways within the urban transportation planning area. Off-model VMT is travel 

that is accounted for within HPMS estimates, but not accounted for within the coded 

transportation network; it typically reflects travel on the local road system. EPA also 

recommends,10 for areas with travel demand models in place, that HPMS adjustments be 

made based on comparison of base year VMT from the transportation model to base year 

HPMS VMT estimates. The ARC calculates HPMS adjustment factors by comparing 

HPMS VMT to travel model VMT by 12 HPMS functional classes for the 2000 

calibration year. The resulting factors are then applied to travel model VMT estimates 

for future analysis years. The following equation was used to calculate the HPMS 

adjustment factors: 

HPMS Adjustment Factori = 2000 HPMS VMTi / 2000 MODEL VMTi

(where i=HPMS functional class) 

 

7

 40 CFR Sections 93.122(a)(7) and 93.122(b)(3) 

8

 Section 3.4.2.6, Procedures for Emission Inventory Preparation, Volume IV: Mobile Sources, EPA420-R92-009, USEPA Office of Air and Radiation, Office of Mobile Sources, 1992. 

9

 40 CFR Section 93.122(a)(7) 

10 40 CFR Section 93.122(b)(3) 

U-6 
To determine the "2000 HPMS VMT," average daily VMT for the year 2000 were 

grouped by the 12 HPMS functional classes for the 13 counties11 that correspond to the 

nonattainment area for the previous 1-hour ozone standard, and, separately, for the 7 

counties12 that were not part of the 1-hour ozone nonattainment area, but are 

nonattainment under the 8-hour ozone standard. County-level HPMS data by functional 

class was taken from the Georgia Department of Transportation's (Georgia DOT) Office 

of Transportation Data "445 Report." Georgia DOT's 445 Report provides information 

on mileage and VMT by route type and road system and contains county-specific State 

Route, County Road and City Street mileage and VMT broken down by functional 

classification. VMT by county and functional class were aggregated to total VMT by 

HPMS functional class. "2000 Travel Demand Model VMT" at the HPMS functional 

class level was derived from the recalibrated 2000 travel model network. HPMS 

adjustment factors for the 13- and 7- county areas are listed below. 

Note that for the HPMS adjustment factors for the 7-county area, urban and rural HPMS 

VMT were combined by HPMS functional classification prior to comparing with ARC 

travel model VMT. Travel model network coding for the 7-county area took place in 

early 2006 and reflects the latest version (from the 2000 Census) of the urbanized area 

definition. The 2000 HPMS data that is used as the base for calculation of the adjustment 

factors reflects the 1990 Census urbanized area definition. Georgia DOT did not update 

to the 2000 Census definitions until calendar year 2005, with their 2004 445 Report. In 

order to avoid a disconnect between travel model VMT in the 7 counties coded with 2000 

Census urban/rural designations and 2000 HPMS VMT that reflects the 1990 definition, 

the urban and rural VMT were combined by functional class before the factors were 

calculated. This produced four unique HPMS adjustment factors for the 7-county area, as 

opposed to 12 unique factors calculated for the 13-county area. 

 

11 (Cherokee, Clayton, Cobb, Coweta, DeKalb, Douglas, Fayette, Forsyth, Fulton, Gwinnett, Henry, 

Paulding, and Rockdale) 

12 (Barrow, Bartow, Carroll, Hall, Newton, Spalding, and Walton) 

U-7 
Table U-1 

HPMS Adjustment Factors – 13 Counties 

Functional Class 

Name 

Functional Class 

Number HPMS VMT Model VMT Factor 

 Rural Interstate 1 5,470,815 8,583,156 0.64 

 Rural Principal Arterial 2 3,578,882 3,579,075 1.00 

 Rural Minor Arterial 6 3,821,128 3,343,871 1.14 

 Rural Major Collector 7 3,510,608 4,021,609 0.87 

 Rural Minor Collector 8 1,191,162 1,121,165 1.06 

 Rural Local 9 3,322,148 5,199,188 0.64 

 Urban Interstate 11 35,934,531 35,043,828 1.03 

 Urban Other Freeway 12 5,765,979 2,422,195 2.38 

 Urban Principal Arterial 14 10,398,680 15,341,281 0.68 

 Urban Minor Arterial 16 22,101,606 18,118,598 1.22 

 Urbanized Collector 17 7,540,916 6,098,164 1.24 

 Urbanized Local 19 15,412,042 15,841,739 0.97 

Table U-2 

HPMS Adjustment Factors – 7 Counties 

Functional Class 

Name 

Functional Class 

Number HPMS VMT Model VMT Factor 

 Rural Interstate 1 4,160,787 2,426,269 0.85 

 Rural Principal Arterial 2 3,912,496 1,299,608 0.97 

 Rural Minor Arterial 6 3,843,626 1,784,578 0.97 

 Rural Major Collector 7 2,498,042 1,435,602 1.80 

 Rural Minor Collector 8 1,019,255 303,600 1.80 

 Rural Local 9 3,112,673 1,515,043 1.09 

 Urban Interstate 11 322,200 2,510,593 0.85 

 Urban Other Freeway 12 0 310,430 0.85 

 Urban Principal Arterial 14 2,874 1,979,977 0.97 

 Urban Minor Arterial 16 17,640 2,952,583 0.97 

 Urbanized Collector 17 0 216,380 1.80 

 Urbanized Local 19 20,796 1,353,590 1.09 

Summer (seasonal) adjustment factors are used to convert from average annual daily 

VMT to average summer-season daily VMT for the purposes of ozone precursor 

emissions modeling.13 Seasonal adjustment factors reflect the latest factors provided by 

the Georgia DOT Office of Transportation Data, on August 9, 2006. Summer-adjustment 

factors for the 13- and 7- county geographies are listed below. 

 

13 Procedures for Emission Inventory Preparation, Volume IV: Mobile Sources, Section 3.4.2.6, EPA420-

R-92-009, USEPA Office of Air and Radiation, Office of Mobile Sources, 1992. 

U-8 
Table U-3 

Summer Adjustment Factors 

Functional Class Name 13-County Factor 7-County Factor 

 Rural Interstate 1.05 1.04 

 Rural Principal Arterial 1.02 1.02 

 Rural Minor Arterial 1.01 1.01 

 Rural Major Collector 1.00 1.00 

 Rural Minor Collector 1.01 1.01 

 Rural Local 1.01 1.01 

 Urban Interstate 1.02 1.00 

 Urban Other Freeway 1.03 1.00 

 Urban Principal Arterial 0.99 1.00 

 Urban Minor Arterial 0.99 0.99 

 Urbanized Collector 0.97 1.00 

 Urbanized Local 0.97 0.97 

HPMS adjustment factors were multiplied by the seasonal adjustment factors for each 

HPMS functional classification to produce a set of VMT adjustment factors by HPMS 

functional classification for 13-county and 7-county portions of the 20-county 

nonattainment area, separately. VMT adjustment factors are listed below. 

Table U-4 

VMT Adjustment Factors 

Functional Class Name 13-County Factor 7-County Factor 

 Rural Interstate 0.67 0.89 

 Rural Principal Arterial 1.02 0.99 

 Rural Minor Arterial 1.16 0.98 

 Rural Major Collector 0.88 1.81 

 Rural Minor Collector 1.07 1.81 

 Rural Local 0.64 1.10 

 Urban Interstate 1.05 0.86 

 Urban Other Freeway 2.44 0.85 

 Urban Principal Arterial 0.67 0.97 

 Urban Minor Arterial 1.21 0.96 

 Urbanized Collector 1.21 1.80 

 Urbanized Local 0.95 1.06 

MOBILE6 Emission Factors

Emission factors were produced for 2.5 miles per hour (mph), then 3 mph to 65 mph, 

inclusive, in one mile per hour increments for VOC and NOx using EPA's 

MOBILE6.2.03 model. Mobile source emissions are calculated by multiplying the VMT 

for each link14 in the travel model network by the corresponding VMT adjustment factor 

 

14 A link refers to a section of the modeled road network in which none of the describing attributes change 

(e.g., link "A" is a segment of a highway that has 4 lanes with speed limit of 55. If the number of lanes 

changes, then a new link should be coded). 

U-9 
(by HPMS class) by an emission factor that corresponds to the congested flow speed of 

the link. Link level emissions are then summed to the time of day and daily level for 

reporting purposes. 

Emission factors reflect two types of programs, the federally mandated motor vehicle 

emission control programs and the locally specific parameters for Atlanta. 

Federal Programs Regional Parameters

National Low Emission Vehicle Standards Average Fuel Volatility 

Heavy-Duty Vehicle Emission Standards Vehicle Registration Information 

Tier 1 Emission Standards Ambient Weather Conditions 

Tier 2 Emission Standards15 Inspection & Maintenance Program 

Low-Sulfur Georgia Gasoline16

MOBILE6 estimates emissions for four types of "driving cycle" - arterial/collector, 

freeway, ramp, and local road. It is assumed that all VMT by motor vehicles will occur 

in one of these four driving cycles. Each driving cycle implies different assumptions 

about vehicle activity and different emission estimates in MOBILE6. The definitions of 

the different driving cycles from EPA's Technical Guidance on the Use of MOBILE6.2 

for Emission Inventory Preparation17 are given below. 

Freeway Driving Cycle 

In MOBILE6, "freeway" VMT refers to driving that occurs on roadways that do not have 

traffic signals, that usually have limited access (via converging ramps) and have free flow 

speeds greater than 50 miles per hour. These roadways are usually divided and have 

more than one lane in each direction. This definition does not include short sections (less 

than two miles) of a roadway between signals, but could include longer roadway 

segments that effectively act as freeways. 

Arterial/Collector Driving Cycle 

In MOBILE6, "arterial/collector" VMT refers to driving that occurs on roadways that 

have signalized traffic control. These roadways are not freeways, because they have 

traffic signals, but they may be divided, multiple lanes, one-way and have high free-flow 

speeds. However, traffic will be stopped periodically by traffic signals and will be 

further affected by access to the roadway by driveways and un-signalized intersections. 

Even in free flow, the driving on arterial/collector roadways will be characterized by 

cruising periods interrupted by traffic signals. 

Local Roadway Driving Cycle 

 

15 (beginning with 2004 models) 

16 when different from federal sulfur levels 

17 http://www.epa.gov/otaq/models/mobile6/420r04013.pdf

U-10 
In MOBILE6, "local roadway" VMT refers to driving on roadways that are not normally 

considered as part of the traffic network. These roadways do not have traffic lights and 

rarely have more than one lane in each direction. They usually allow vehicle parking on 

the roadway surface and traffic control is handled via stop/yield signs. Speed limits are 

normally 30 miles per hour or less. The driving cycle used in MOBILE6 to model local 

roadways is fixed at an average speed of 12.9 miles per hour. Driving on local roadways 

is characterized by extremely low speeds and frequent stops at intersections. 

Freeway Ramp 

In MOBILE6, "freeway ramp" VMT refers to the access roadways for freeways. It 

includes both traffic entering the freeway and exiting. Driving on freeway ramps is 

characterized by rapid acceleration from stop or low speeds to freeway speeds and 

decelerations from freeway speeds to low speeds or stop. Freeway ramp activity is not 

included in the MOBILE6 freeway roadway definition. Therefore, all freeway activity 

must include a corresponding freeway ramp activity to account for acceleration and 

deceleration to and from freeway speeds. 

Many areas do not explicitly account for freeway ramps as a separate roadway type so 

EPA developed a default ramp fraction (8% of freeway travel) for MOBILE6 users to 

account for this. This approach is not necessary for Atlanta's nonattainment area freeway 

emission estimates because freeway ramps have been explicitly defined in the ARC 

highway network. Freeway ramps have been defined as separate facilities stratified by the 

type of design and speed, high, medium and low. High-speed ramps represent ramps that 

connect freeway-to-freeway travel, such as I-285 to I-85N, while the lower speed ramps 

are for access to a freeway from an arterial or egress from a freeway to an arterial. The 

high-speed ramps in the ARC model have significantly higher free-flow speeds than the 

lower speed ramps and are not characterized by rapid acceleration or by deceleration 

from freeway speeds to low speeds or stops. Based on guidance from EPA, emissions 

for high-speed freeway ramps are estimated using non-ramp freeway emission factors 

while emissions for lower speed freeway ramps are estimated using freeway ramp 

emission factors. 

In MOBILE6, only arterial/collector and freeway emissions are speed sensitive. Emission 

factors were produced for 2.5 miles per hour and, in one mile per hour increments, 

between 3 mph and 65 mph, inclusive, for these two driving cycles. The all-vehicles 

composite emission factors were used to develop the mobile source emissions inventories 

for the MVEB. 

Emission factors are applied to travel model VMT based on the appropriate driving cycle 

and congested flow speed. The mapping of MOBILE6 roadway type to both HPMS 

functional class and ARC roadway facility type18 used for the MVEB emissions 

modeling is shown in Tables C-5 and C-6, below. The appropriate MOBILE6 roadway 

 

18 ARC uses a more refined breakdown of roadway types for travel demand modeling to enable a more 

accurate estimate of roadway volumes and speeds. ARC roadway types are referred to as Facility Types. 

U-11 
type can be determined by using the facility type definitions in the highway network 

except for the rural other principal arterial. EPA believes that facilities with the HPMS 

classification of rural other principal arterial should be modeled using a combination of 

the freeway and ramp emission factors. EPA has recommended that the freeway 

emission factors be applied to 92% of the VMT while the ramp emission factors be 

applied for the remaining 8% of the VMT for these facilities. This is the only case where 

a combination of emission factors by driving cycle is used for the same functional 

classification. In the ARC highway networks, facilities with rural other principal arterial 

HPMS classifications have different facility types, ranging from expressway to different 

types of arterials. Within the ARC emissions modeling procedure, the HPMS functional 

classification, facility type, and free-flow speed for each link are checked to determine 

the appropriate MOBILE6 driving cycle for this category. Only links with a facility type 

of arterial or collector, an HPMS classification of rural other principal arterial, and a freeflow speed greater than 50 mph, will have the VMT adjusted based on the above criteria. 

Facilities with a freeway facility type and an HPMS classification of rural other principal 

arterial will not be adjusted. Table U-5 lists the mapping of HPMS functional classes to 

MOBILE6 driving cycles and Table U-6 lists the mapping of the ARC facility types to 

the MOBILE6 driving cycles. 

Table U-5 

HPMS Functional Classifications 

Mapped to MOBILE6 Driving Cycles 

HPMS Highway Functional System MOBILE6 Driving Cycle 

Rural interstate Freeway and freeway ramp 

Rural other principal arterial Freeway and freeway ramp 

Rural minor arterial Arterial/collector 

Rural major collector Arterial/collector 

Rural minor collector Arterial/collector 

Rural local Local 

Urban interstate Freeway and freeway ramp 

Urban other freeways Freeway and freeway ramp 

Urban other principal arterial Arterial/collector 

Urban minor arterial Arterial/collector 

Urban collector Arterial/collector 

Urban local Local 

U-12 
Table U-6 

Listing of ARC Facility Type Classifications 

by MOBILE 6 Driving Cycles

Facility Type Classification Code Area Type MOBILE6 Driving Cycle 

Interstate/Freeways 1 Urban/Rural Freeway 

Parkway 2 Urban/Rural Freeway 

HOV Buffer Separated 3 Urban/Rural Freeway 

HOV Barrier Separated 

High Speed Ramps/CD 

Roads 

4 

5 

Urban/Rural 

Urban/Rural 

Freeway 

Freeway 

Principal Arterial – Class I* 12 Rural Arterial/collector or Freeway 

and Ramp 

Principal Arterial – Class I 12 Urban Arterial/collector 

Principal Arterial – Class II* 13 Rural Arterial/collector or Freeway 

and Ramp 

Principal Arterial – Class II 13 Urban Arterial/collector 

Minor Arterials – Class I 14 Rural Arterial/collector 

Minor Arterials – Class I 14 Urban Arterial/collector 

Minor Arterials – Class II 15 Rural Arterial/collector 

HOV Arterials 16 Urban/Rural Arterial/collector 

Major Collector 17 Urban/Rural Arterial/collector 

Minor Collector 18 Urban/Rural Arterial/collector 

Medium Speed Ramp 6 Urban/Rural Ramp 

Low Speed Ramp 7 Urban/Rural Ramp 

Loop Ramp 8 Urban/Rural Ramp 

Off Ramp w/Intersection 9 Urban/Rural Ramp 

On Ramp w/Intersection 10 Urban/Rural Ramp 

Planned Ramps 

w/Intersections 

19 Urban/Rural Ramp 

Planned Directional Ramps 20 Urban/Rural Ramp 

Centroid Connectors 0 Urban/Rural Local 

*If HPMS classification is Rural Other Principal Arterial and free-flow speed is >50 

mph - 92% of VMT allocated to freeway while 8% allocated to ramp 

Specific variables within the MOBILE6 inputs for the MVEB inventories are 

documented below. 

• Ambient Weather Conditions 

MOBILE6 allows relative humidity and temperature to be input for each hour of the day, 

with a single entry for barometric pressure. Hourly humidity and temperature inputs, and 

daily barometric pressure, were derived from National Weather Service Local 

Climatological Data from the 10 days with the highest ozone concentrations for the threeyear period 2000-2002. The hourly humidities and temperatures were averaged across 

the 10 days. The daily average barometric pressures for the 10 days were also averaged. 

See Exhibit 1 for details. 

U-13 
• Fleet Age 

Separate, area-specific registration distributions by age for the 13- and 7-county parts of 

the Atlanta ozone nonattainment area, developed using registration data obtained from 

R.L. Polk & Company,19 were modeled. In keeping with EPA guidance,20 the 

MOBILE6 default distribution was used for the heaviest (Class 8B) heavy-duty vehicles. 

• Gasoline21

The 2009 Attainment budget year mobile source emissions inventories for the Atlanta 8-

hour ozone nonattainment area MVEB reflect the effects of the low-sulfur and low RVP 

Phase 2 Georgia Gasoline required by state rule in and near the nonattainment area. In 

addition, a 100% market share of 10% by volume ethanol blend (E10), with an RVP 

waiver, was assumed. Per Georgia's Gasoline Marketing Rule, 391-3-1-.02(2)(bbb), this 

waiver allows the RVP of ethanol-blend gasoline to rise as high as 8.0 psi. 

• Vehicle Inspection and Maintenance Program 

For 2009 mobile source emissions modeling, the enhanced I/M program22 in place in the 

13-county part of the nonattainment area was modeled. This annual program requires 

onboard diagnostics system checks on 1996 and newer model year cars and light trucks, 

2-mode ASM tests on 25-year-old through 1995 model year vehicles; a check for 

catalytic converter tampering on 25-year-old through 1995 model year vehicles; and a gas 

cap pressure test on all subject vehicles. 

Additional detail related to development of emission factors used for the Ozone 

Attainment Plan emissions inventory is provided in Appendix U, Exhibit 3. 

Emission Inventory Files 

The MOBILE6 input variables are specified in the input files. Exhibit 5 contains 

abbreviated versions of the input files used to calculate emission factors for the 2009 

nonattainment area MVEB inventories. There is a separate scenario in each input for 

 

19 Registration data was from R. L. Polk & Co.'s National Vehicle Population Profile ® current as of 

October 2002 and from R. L. Polk & Co.'s TIPNet ® current as of March 2003. See Exhibit 2 for more 

details on the registration distributions by age. 

20 "EPA encourages and recommends the use of actual locality-specific...registration distributions by age in 

the development of SIP emission inventories. One exception to this would be areas having relatively few 

local HDDV registrations, but significant interstate trucking activity within the local area. Such areas may 

want to retain and use the [MOBILE] national registration distributions." Section 2.2.3.6, User's Guide to 

MOBILE5. 21 In 1999, Georgia's two-phase gasoline sulfur control program limited average sulfur in gasoline sold in 

the 13-county Atlanta area and in 12 surrounding counties to 150 parts per million (ppm). In addition, 

there is a seasonal (June 1 to September 15) 7.0 pounds per square inch (psi) Reid vapor pressure (RVP) 

cap on gasoline sold in this Phase 1 area. In 2003, Phase 2 of Georgia's gasoline rule reduced average 

sulfur to 30 ppm and added 20 additional counties outside the 20-county ozone nonattainment area to the 

sulfur and (seasonal) RVP control program. 

22 See Rules for Enhanced Inspection and Maintenance, Chapter 391-3-20, 

http://www.gaepd.org/Files_PDF/rules/rules_exist/391-3-20.pdf

U-14 
each speed, with only the speed varying. To conserve space, most of the speed scenarios 

are omitted from these inputs. 

Exhibit 6 documents the calculations of the emissions reductions credit loss from the 

senior I/M exemption. 

Loaded network files that list VMT, speeds, FIPS23 code, facility type code, HPMS 

functional class code, VOC and NOx, etc., by time of day for each network link are 

produced by the emissions calculation model. These files were imported into database 

tables and daily emissions were then summarized. The data tables and the SQL queries 

used to summarize 2009 link-level emissions are contained in a Microsoft Access file 

available on request. 

 

 

23 Federal Information Processing Standard, a numerical code indicating state and county. 

U-15 


Appendix U, Exhibit 2 

U2-1 

Georgia's Revised MOBILE6 Registration Distributions by Age

Overview

R.L. Polk & Co. (Polk) maintains databases encompassing all registered vehicles in operation by state. Polk 

acquires the source registration data from the states and then processes and enhances the data. Key data 

elements Polk used for grouping vehicle registered in Georgia by their appropriate composite (i.e., gasoline and 

diesel) MOBILE6 vehicle types were: vehicle make, vehicle model, engine make, engine model, fuel type, cab 

type, bed length, wheel configuration, vehicle type, gross vehicle weight rating (GVWR)24 class, model year, 

and registration geography (i.e., county). 

Vehicle characteristic data elements used by Polk are derived from the unique 17 position vehicle identification 

number (VIN) assigned to every vehicle. Vehicle geography is assigned based on the registration address 

linked to each VIN. 

In order to assign a MOBILE6 category to all registered vehicles, Polk constructed a master vehicle workfile 

using data from Polk’s TIPNet and NVPP databases. This master vehicle workfile accounts for all registered 

vehicles, including: cars, vans, sport utility vehicles, trucks, buses, school buses, and motorcycles (GVWR 

classes 1-8 + motorcycle). The GVWR classes are: 

Class 1 0 - 6,000 lbs. 

Class 2 6,001 - 10,000 lbs. 

Class 3 10,001 - 14,000 lbs. 

Class 4 14,001 - 16,000 lbs. 

Class 5 16,001 - 19,500 lbs. 

Class 6 19,501 - 26,000 lbs. 

Class 7 26,001 - 33,000 lbs. 

Class 8 33,001 - 150,000 lbs. 

The TIPNet database contains vehicles from full-size pickups/vans through class 8 (GVWR classes 1c-8), and is 

structured to serve the commercial vehicle market. The NVPP database contains vehicles GVWR classes 1-3 

and is designed to serve the car, light truck/van, and motorcycle aftermarket. 

Using the data elements listed above, Polk assigned one of the 16 MOBILE6 categories to each of the vehicles 

in the workfile. Care was taken to assure that no makes and models are duplicated between the two databases. 

Note that the unit volume for same make/model vehicles can be divided among two or more MOBILE6 

categories due to varying vehicle types and GVWR classes within a specific make/model. TIPNet data supplies 

GVWR classes 1c-8 (full-size pickups/vans & heavier), while NVPP data provides passenger car, motorcycle, 

light truck, and light vans from GVWR class 1. 

 

24 The GVWR is the maximum weight of the vehicle when it is fully loaded, as specified by the manufacturer. 
Appendix U, Exhibit 2 

U2-2 

The 16 composite MOBILE6 vehicle types are listed and defined below, with examples of the types of vehicles 

they include. 

Number Abbreviation Description

1 LDV Light-Duty Vehicles (Passenger Cars)

- Class 1 GVWR 

- Include: Passenger Cars 

- Fuel: All Types 

- Source: R.L. Polk NVPP as of October 2002 

2 LDT1 Light-Duty Trucks 1 (0-6,000 lbs. GVWR, 0-3,750 lbs. LVW25) 

- Class 1 GVWR 

- Trucks, SUVs, & Vans 

- Exclude Full-Size Pickups & Vans 

- Fuel: All Types 

- Source: R.L. Polk NVPP as of October 2002 

3 LDT2 Light-Duty Trucks 2 (0-6,000 lbs. GVWR, 3,751-5,750 lbs. LVW) 

- Class 1 GVWR 

- Trucks, SUVs, & Vans 

- Fuel: All Types 

- Include all Full-Size Pickups & Vans (e.g. 150/1500 series vehicles: F150, C/K 1500, E150, Ram 

1500 etc.) 

- Include Vehicle Types: Incomplete Pickup + Cab Chassis 

- Exclude Vehicle Types: School Bus + Bus Non-School (Coach) 

- Source: R.L. Polk TIPNet as of March 2003 & NVPP as of October 2002 

4 LDT3 Light-Duty Trucks 3 (6,001-8,500 lbs. GVWR, 0-5,750 lbs. ALVW26) 

- Class 2 GVWR 

- Trucks, SUVs, & Vans 

- GVWR: 6,001-8,000 for Ford, Chevy, Dodge, plus all Toyota Tundra Models 

- Fuel: All Types 

- Exclude: Pickups with Long Bed or Vans with Extended Length (Except Tundra) 

- Exclude Vehicle Types: Incomplete Pickup + Cab Chassis + Incomplete Vehicle + Straight Truck + 

School Bus + Bus Non-School (Coach) 

- Source: R.L. Polk TIPNet as of March 2003 & NVPP as of October 2002 

 

25 Loaded vehicle weight, the weight of vehicle sitting empty (curb weight) plus 300 pounds. 

26 Adjusted loaded vehicle weight, average of the gross vehicle weight and the curb weight. 
Appendix U, Exhibit 2 

U2-3 

Georgia's Revised MOBILE6 Registration Distribution by Age – continued 

Number Abbreviation Description

5 LDT4 Light-Duty Trucks 4 (6,001-8,500 lbs. GVWR, >5,750 lbs. ALVW) 

- Class 2 GVWR 

- Trucks, SUVs, & Vans 

- GVWR: 6,001-8,000 for Ford, Chevy, & Dodge 

- Exclude: all Toyota Tundra Models 

- Fuel: All Types 

- Include: Pickups with Long Bed or Vans with Extended Length 

- Include Vehicle Types: Incomplete Pickup + Cab Chassis + Incomplete Vehicle + Straight Truck 

- Exclude Vehicle Types: School Bus + Bus Non-School (Coach) 

- Source: R.L. Polk TIPNet as of March 2003 

6 HDV2B Class 2b Heavy-Duty Vehicles (8,501-10,000 lbs. GVWR) 

- Class 2 GVWR 

- Trucks, SUVs, & Vans 

- GVWR: 8,001-10,000 for Ford, Chevy, & Dodge 

- Exclude: All Toyota Tundra Models 

- Fuel: All Types 

- Include: Pickups with Long Bed or Vans with Extended Length 

- Include Vehicle Types: Incomplete Pickup + Cab Chassis + Incomplete Vehicle + Straight Truck 

- Exclude Vehicle Types: School Bus + Bus Non-School (Coach) 

- Source: R.L. Polk TIPNet as of March 2003 

7 HDV3 Class 3 Heavy-Duty Vehicles (10,001-14,000 lbs. GVWR) 

- Class 3 GVWR 

- Trucks, SUVs, & Vans 

- Fuel: All Types 

- Exclude Vehicle Types: School Bus + Bus Non-School (Coach) 

- Source: R.L. Polk TIPNet as of March 2003 

8 HDV4 Class 4 Heavy-Duty Vehicles (14,001-16,000 lbs. GVWR) 

- Class 4 GVWR 

- Trucks, SUVs, & Vans 

- Fuel: All Types 

- Exclude Vehicle Types: School Bus + Bus Non-School (Coach) 

- Source: R.L. Polk TIPNet as of March 2003 

9 HDV5 Class 5 Heavy-Duty Gasoline Vehicles (16,001-19,500 lbs. GVWR) 

- Class 5 GVWR 

- Trucks, SUVs, & Vans 

- Fuel: All Types 

- Exclude Vehicle Types: School Bus + Bus Non-School (Coach) 

- Source: R.L. Polk TIPNet as of March 2003 
Appendix U, Exhibit 2 

U2-4 

Georgia's Revised MOBILE6 Registration Distribution by Age – continued 

Number Abbreviation Description

10 HDV6 Class 6 Heavy-Duty Vehicles (19,501-26,000 lbs. GVWR) 

- Class 6 GVWR 

- Trucks, SUVs, & Vans 

- Fuel: All Types 

- Exclude Vehicle Types: School Bus + Bus Non-School (Coach) 

- Source: R.L. Polk TIPNet as of March 2003 

11 HDV7 Class 7 Heavy-Duty Vehicles (26,001-33,000 lbs. GVWR) 

- Class 7 GVWR 

- Trucks, SUVs, & Vans 

- Fuel: All Types 

- Exclude Vehicle Types: School Bus + Bus Non-School (Coach) 

- Source: R.L. Polk TIPNet as of March 2003 

12 HDV8A Class 8a Heavy-Duty Vehicles (33,001-60,000 lbs. GVWR) 

- Class 8 GVWR 

- Trucks, SUVs, & Vans 

- Fuel: All Types 

- Exclude Vehicle Types: School Bus + Bus Non-School (Coach) 

- Include Vehicle Types: 4x2 Non-Tractor Vehicles + All Tractors + Motor Home Chassis 

- Source: R.L. Polk TIPNet as of March 2003 

13 HDV8B Class 8b Heavy-Duty Vehicles (>60,000 lbs. GVWR) 

- Class 8 GVWR 

- Trucks, SUVs, & Vans 

- Fuel: All Types 

- Exclude Vehicle Types: All Tractors + School Bus + Bus Non-School (Coach) 

- Exclude Wheels: 4x2 

- Source: R.L. Polk TIPNet as of March 2003 

14 HDBS School Buses

- Include Vehicle Type: School Bus 

- Fuel: All Types 

- Source: R.L. Polk TIPNet as of March 2003 

15 HDBT Transit & Urban Buses

- Include Vehicle Type: Bus Non-School (Coach) 

- Fuel: All Types 

- Source: R.L. Polk TIPNet as of March 2003 
Appendix U, Exhibit 2 

U2-5 

Georgia's Revised MOBILE6 Registration Distribution by Age – continued 

Number Abbreviation Description

16 MC Motorcycles (All) 

- Fuel: All Types 

- Source: R.L. Polk NVPP as of October 2002 

The data acquired from Polk was queried to determine the number of vehicles registered in the 13- and 7-county 

parts of the Atlanta ozone nonattainment area, and in the 139-county rest-of-state area, by age and MOBILE6 

vehicle type. Results of these queries were used to develop MOBILE6 registration distribution by age inputs. 

For each of those three areas, for each of the 16 composite MOBILE6 vehicle types, the fraction of all vehicles 

of that type which are zero-to-one model year old, two model years old, three model years old, etc., up to the 

oldest category, 25-model-years-and-older, was determined. The resulting MOBILE6 input data is shown on 

the following seven pages. Note that the Polk-derived distribution for Class 8b vehicles (MOBILE6 vehicle 

type 13) is commented out; MOBILE6 defaults were used for these. 
Appendix U, Exhibit 2 

U2-6 

REG DIST 

* 

* The file REGDATA.D contains the default MOBILE6 values for the distribution of 

* vehicles by age for July of any calendar year. There are sixteen (16) 

* sets of values representing 16 combined gasoline/diesel vehicle class 

* distributions. These distributions are split for gasoline and diesel 

* using the separate input (or default) values for diesel sales fractions. 

* Each distribution contains 25 values which represent the fraction of 

* all vehicles in that class (gasoline and diesel) of that age in July. 

* The first number is for age 1 (calendar year minus model year plus one) 

* and the last number is for age 25. The last age includes all vehicles 

* of age 25 or older. The first number in each distribution is an integer 

* which indicates which of the 16 vehicle classes are represented by the 

* distribution. The sixteen vehicle classes are: 

* 

* 1 LDV Light-Duty Vehicles (Passenger Cars) 

* 2 LDT1 Light-Duty Trucks 1 (0-6,000 lbs. GVWR, 0-3750 lbs. LVW) 

* 3 LDT2 Light Duty Trucks 2 (0-6,001 lbs. GVWR, 3751-5750 lbs. LVW) 

* 4 LDT3 Light Duty Trucks 3 (6,001-8500 lbs. GVWR, 0-3750 lbs. LVW) 

* 5 LDT4 Light Duty Trucks 4 (6,001-8500 lbs. GVWR, 3751-5750 lbs. LVW) 

* 6 HDV2B Class 2b Heavy Duty Vehicles (8501-10,000 lbs. GVWR) 

* 7 HDV3 Class 3 Heavy Duty Vehicles (10,001-14,000 lbs. GVWR) 

* 8 HDV4 Class 4 Heavy Duty Vehicles (14,001-16,000 lbs. GVWR) 

* 9 HDV5 Class 5 Heavy Duty Vehicles (16,001-19,500 lbs. GVWR) 

* 10 HDV6 Class 6 Heavy Duty Vehicles (19,501-26,000 lbs. GVWR) 

* 11 HDV7 Class 7 Heavy Duty Vehicles (26,001-33,000 lbs. GVWR) 

* 12 HDV8A Class 8a Heavy Duty Vehicles (33,001-60,000 lbs. GVWR) 

* 13 HDV8B Class 8b Heavy Duty Vehicles (>60,000 lbs. GVWR) 

* 14 HDBS School Busses 

* 15 HDBT Transit and Urban Busses 

* 16 MC Motorcycles (All) 

* 

* The 25 age values are arranged in two rows of 10 values followed by a row 

* with the last 5 values. Comments (such as this one) are indicated by 

* an asterisk in the first column. Empty rows are ignored. Values are 

* read "free format," meaning any number may appear in any row with as 

* many characters as needed (including a decimal) as long as 25 values 

* follow the initial integer value separated by a space. 

* 

* If all 16 vehicle classes do not need to be altered from the default 

* values, then only the vehicle classes that need to be changed need to 

* be included in this file. The order in which the vehicle classes are 

* read does not matter, however each vehicle class set must contain 25 

* values and be in the proper age order. 

* ___________________________________________________________________________ 

* 

* This file specifies the local registration distribution by age 

* (MOBILE6 defaults for heavy-heavy-duties) for the 13-county Atlanta 

* nonattainment area. 

* Sources of registration data: R. L. Polk & Co.'s National Vehicle 

* Population Profile (R) as of October 2002 and R. L. Polk & Co.'s 

* TIPNet (R) as of March 2003. 

* 

* LDV 

1 0.0238 0.0712 0.0687 0.0771 0.0729 0.0671 0.0689 0.0656 0.0763 0.0618 

 0.0559 0.0461 0.0399 0.0370 0.0325 0.0267 0.0214 0.0166 0.0126 0.0089 

 0.0054 0.0032 0.0026 0.0023 0.0354 

* LDT1 

2 0.0307 0.1252 0.1152 0.1191 0.0915 0.0859 0.0689 0.0626 0.0596 0.0513 

 0.0412 0.0261 0.0227 0.0155 0.0163 0.0139 0.0122 0.0093 0.0058 0.0039 

 0.0023 0.0014 0.0009 0.0006 0.0178 
Appendix U, Exhibit 2 

U2-7 

* LDT2 

3 0.0040 0.0132 0.0896 0.0494 0.0367 0.0774 0.1014 0.0002 0.0205 0.0378 

 0.0480 0.0415 0.0384 0.0566 0.0589 0.0649 0.0421 0.0538 0.0474 0.0395 

 0.0282 0.0227 0.0278 0.0000 0.0000 

* LDT3 

4 0.0627 0.1758 0.1558 0.1027 0.0921 0.0512 0.0582 0.0554 0.0554 0.0440 

 0.0229 0.0174 0.0111 0.0125 0.0135 0.0108 0.0115 0.0133 0.0122 0.0092 

 0.0058 0.0039 0.0027 0.0000 0.0000 

* LDT4 

5 0.0210 0.0636 0.0778 0.0756 0.0718 0.0501 0.0546 0.0552 0.0836 0.0737 

 0.0546 0.0449 0.0365 0.0440 0.0504 0.0385 0.0240 0.0214 0.0194 0.0191 

 0.0126 0.0050 0.0024 0.0000 0.0000 

* HDV2B 

6 0.0613 0.1508 0.1166 0.1022 0.0976 0.0405 0.0653 0.0484 0.0452 0.0337 

 0.0285 0.0195 0.0161 0.0194 0.0240 0.0264 0.0148 0.0223 0.0217 0.0170 

 0.0104 0.0097 0.0075 0.0002 0.0008 

* HDV3 

7 0.0436 0.1152 0.1269 0.1138 0.1180 0.0412 0.0567 0.0443 0.0518 0.0435 

 0.0272 0.0227 0.0190 0.0253 0.0266 0.0248 0.0182 0.0227 0.0156 0.0126 

 0.0062 0.0051 0.0031 0.0012 0.0147 

* HDV4 

8 0.0341 0.0879 0.1057 0.1360 0.1267 0.0529 0.0835 0.0551 0.0627 0.0406 

 0.0341 0.0191 0.0180 0.0216 0.0335 0.0282 0.0126 0.0084 0.0099 0.0086 

 0.0057 0.0037 0.0014 0.0003 0.0098 

* HDV5 

9 0.0554 0.1030 0.1239 0.1313 0.1482 0.0330 0.0683 0.0529 0.0484 0.0293 

 0.0218 0.0178 0.0079 0.0107 0.0075 0.0065 0.0111 0.0049 0.0045 0.0070 

 0.0050 0.0039 0.0065 0.0010 0.0901 

* HDV6 

10 0.0203 0.0362 0.0744 0.1076 0.1035 0.0801 0.0549 0.0462 0.0660 0.0355 

 0.0304 0.0249 0.0217 0.0202 0.0194 0.0250 0.0198 0.0179 0.0208 0.0148 

 0.0090 0.0082 0.0079 0.0051 0.1303 

* HDV7 

11 0.0765 0.0383 0.0646 0.0648 0.0639 0.0495 0.0357 0.0402 0.0622 0.0399 

 0.0341 0.0357 0.0426 0.0427 0.0601 0.0549 0.0356 0.0332 0.0364 0.0231 

 0.0113 0.0081 0.0106 0.0161 0.0200 

* HDV8A 

12 0.0588 0.0966 0.1287 0.0953 0.0880 0.0578 0.0489 0.0547 0.0514 0.0367 

 0.0390 0.0204 0.0180 0.0208 0.0292 0.0263 0.0276 0.0204 0.0321 0.0128 

 0.0071 0.0056 0.0057 0.0055 0.0127 

* HDV8B 

*13 0.0288 0.0384 0.0796 0.0885 0.0852 0.0444 0.0576 0.0469 0.1047 0.0501 

* 0.0455 0.0292 0.0343 0.0388 0.0286 0.0363 0.0197 0.0183 0.0251 0.0117 

* 0.0053 0.0054 0.0057 0.0116 0.0601 

* HDBS 

14 0.0374 0.0570 0.0505 0.0734 0.0639 0.0734 0.0491 0.0664 0.0805 0.0243 

 0.0610 0.0473 0.0675 0.0771 0.0306 0.0506 0.0132 0.0104 0.0121 0.0097 

 0.0071 0.0049 0.0059 0.0078 0.0191 

* HDBT 

15 0.0029 0.0279 0.0999 0.1233 0.0602 0.0595 0.0426 0.0587 0.0206 0.0492 

 0.0286 0.0477 0.0066 0.1740 0.0382 0.0668 0.0125 0.0250 0.0117 0.0081 
Appendix U, Exhibit 2 

U2-8 

 0.0125 0.0147 0.0088 0.0000 0.0000 

* MC 

16 0.0005 0.1005 0.1186 0.0993 0.0751 0.0612 0.0535 0.0478 0.0397 0.0362 

 0.0339 0.3336 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 

 0.0000 0.0000 0.0000 0.0000 0.0000 
Appendix U, Exhibit 2 

U2-9 

REG DIST 

* 

* The file REGDATA.D contains the default MOBILE6 values for the distribution of 

* vehicles by age for July of any calendar year. There are sixteeen (16) 

* sets of values representing 16 combined gasoline/diesel vehicle class 

* distributions. These distributions are split for gasoline and diesel 

* using the separate input (or default) values for diesel sales fractions. 

* Each distribution contains 25 values which represent the fraction of 

* all vehicles in that class (gasoline and diesel) of that age in July. 

* The first number is for age 1 (calendar year minus model year plus one) 

* and the last number is for age 25. The last age includes all vehicles 

* of age 25 or older. The first number in each distribution is an integer 

* which indicates which of the 16 vehicle classes are represented by the 

* distribution. The sixteen vehicle classes are: 

* 

* 1 LDV Light-Duty Vehicles (Passenger Cars) 

* 2 LDT1 Light-Duty Trucks 1 (0-6,000 lbs. GVWR, 0-3750 lbs. LVW) 

* 3 LDT2 Light Duty Trucks 2 (0-6,001 lbs. GVWR, 3751-5750 lbs. LVW) 

* 4 LDT3 Light Duty Trucks 3 (6,001-8500 lbs. GVWR, 0-3750 lbs. LVW) 

* 5 LDT4 Light Duty Trucks 4 (6,001-8500 lbs. GVWR, 3751-5750 lbs. LVW) 

* 6 HDV2B Class 2b Heavy Duty Vehicles (8501-10,000 lbs. GVWR) 

* 7 HDV3 Class 3 Heavy Duty Vehicles (10,001-14,000 lbs. GVWR) 

* 8 HDV4 Class 4 Heavy Duty Vehicles (14,001-16,000 lbs. GVWR) 

* 9 HDV5 Class 5 Heavy Duty Vehicles (16,001-19,500 lbs. GVWR) 

* 10 HDV6 Class 6 Heavy Duty Vehicles (19,501-26,000 lbs. GVWR) 

* 11 HDV7 Class 7 Heavy Duty Vehicles (26,001-33,000 lbs. GVWR) 

* 12 HDV8A Class 8a Heavy Duty Vehicles (33,001-60,000 lbs. GVWR) 

* 13 HDV8B Class 8b Heavy Duty Vehicles (>60,000 lbs. GVWR) 

* 14 HDBS School Busses 

* 15 HDBT Transit and Urban Busses 

* 16 MC Motorcycles (All) 

* 

* The 25 age values are arranged in two rows of 10 values followed by a row 

* with the last 5 values. Comments (such as this one) are indicated by 

* an asterisk in the first column. Empty rows are ignored. Values are 

* read "free format," meaning any number may appear in any row with as 

* many characters as needed (including a decimal) as long as 25 values 

* follow the initial integer value separated by a space. 

* 

* If all 16 vehicle classes do not need to be altered from the default 

* values, then only the vehicle classes that need to be changed need to 

* be included in this file. The order in which the vehicle classes are 

* read does not matter, however each vehicle class set must contain 25 

* values and be in the proper age order. 

* ___________________________________________________________________________ 

* 

* This file specifies the local registration distribution by age 

* (MOBILE6 defaults for heavy-heavy-duties) for the 7 additional counties 

* in the Atlanta ozone nonattainment area under the 8-hour standard 

* (Barrow, Bartow, Carroll, Hall, Newton, Spalding, and Walton) 

* 

* Sources of registration data: R. L. Polk & Co.'s National Vehicle 

* Population Profile (R) as of October 2002 and R. L. Polk & Co.'s 

* TIPNet (R) as of March 2003. 

* 

* LDV 

1 0.0099 0.0441 0.0494 0.0577 0.0549 0.0531 0.0572 0.0576 0.0699 0.0611 

 0.0588 0.0504 0.0480 0.0450 0.0455 0.0401 0.0336 0.0293 0.0257 0.0197 

 0.0122 0.0070 0.0065 0.0056 0.0576 

* LDT1 

2 0.0179 0.0888 0.0813 0.0871 0.0705 0.0729 0.0612 0.0594 0.0613 0.0590 

 0.0512 0.0359 0.0337 0.0242 0.0302 0.0290 0.0254 0.0218 0.0162 0.0127 
Appendix U, Exhibit 2 

U2-10 

 0.0079 0.0046 0.0029 0.0028 0.0422 

* LDT2 

3 0.0009 0.0039 0.0178 0.0190 0.0232 0.0535 0.0785 0.0000 0.0150 0.0355 

 0.0458 0.0422 0.0435 0.0647 0.0700 0.0807 0.0526 0.0732 0.0742 0.0645 

 0.0474 0.0423 0.0514 0.0000 0.0000 

* LDT3 

4 0.0421 0.1078 0.0988 0.0847 0.0936 0.0581 0.0639 0.0679 0.0712 0.0577 

 0.0301 0.0245 0.0148 0.0166 0.0215 0.0186 0.0206 0.0276 0.0281 0.0221 

 0.0137 0.0090 0.0068 0.0000 0.0002 

* LDT4 

5 0.0067 0.0308 0.0415 0.0532 0.0562 0.0408 0.0455 0.0530 0.0788 0.0732 

 0.0581 0.0550 0.0408 0.0557 0.0738 0.0643 0.0293 0.0355 0.0337 0.0333 

 0.0251 0.0097 0.0057 0.0000 0.0000 

* HDV2B 

6 0.0380 0.0608 0.0692 0.0790 0.0900 0.0308 0.0712 0.0645 0.0594 0.0450 

 0.0419 0.0273 0.0209 0.0239 0.0388 0.0421 0.0245 0.0366 0.0406 0.0341 

 0.0234 0.0188 0.0172 0.0003 0.0018 

* HDV3 

7 0.0309 0.0819 0.1181 0.0912 0.1191 0.0354 0.0470 0.0409 0.0529 0.0319 

 0.0319 0.0287 0.0237 0.0282 0.0295 0.0297 0.0262 0.0384 0.0320 0.0264 

 0.0102 0.0078 0.0057 0.0030 0.0297 

* HDV4 

8 0.0186 0.0393 0.0464 0.0813 0.0968 0.0416 0.0840 0.0579 0.0778 0.0615 

 0.0371 0.0323 0.0323 0.0358 0.0566 0.0526 0.0248 0.0168 0.0195 0.0199 

 0.0168 0.0088 0.0062 0.0004 0.0349 

* HDV5 

9 0.0275 0.0344 0.0516 0.0938 0.1188 0.0181 0.0723 0.0491 0.0430 0.0267 

 0.0181 0.0155 0.0112 0.0103 0.0060 0.0103 0.0189 0.0164 0.0112 0.0181 

 0.0155 0.0086 0.0215 0.0009 0.2823 

* HDV6 

10 0.0086 0.0166 0.0350 0.0472 0.0555 0.0377 0.0306 0.0276 0.0489 0.0316 

 0.0225 0.0230 0.0196 0.0247 0.0196 0.0264 0.0250 0.0296 0.0338 0.0247 

 0.0174 0.0161 0.0139 0.0100 0.3545 

* HDV7 

11 0.0119 0.0222 0.0245 0.0431 0.0542 0.0435 0.0392 0.0447 0.0566 0.0392 

 0.0328 0.0356 0.0451 0.0558 0.0392 0.0550 0.0534 0.0506 0.0550 0.0324 

 0.0237 0.0214 0.0281 0.0380 0.0550 

* HDV8A 

12 0.0392 0.0365 0.0371 0.0775 0.0859 0.0669 0.0515 0.0606 0.0775 0.0546 

 0.0513 0.0309 0.0274 0.0358 0.0413 0.0443 0.0311 0.0276 0.0267 0.0232 

 0.0102 0.0111 0.0104 0.0109 0.0302 

* HDV8B 

*13 0.0159 0.0295 0.0577 0.0759 0.0632 0.0577 0.0622 0.0582 0.0618 0.0473 

* 0.0227 0.0159 0.0241 0.0204 0.0236 0.0395 0.0336 0.0254 0.0391 0.0350 

* 0.0091 0.0132 0.0182 0.0209 0.1299 

* HDBS 

14 0.0705 0.0158 0.0735 0.0668 0.0720 0.0630 0.0285 0.0923 0.1005 0.0045 

 0.0398 0.0330 0.0443 0.0705 0.0338 0.0690 0.0158 0.0128 0.0158 0.0105 

 0.0120 0.0090 0.0090 0.0083 0.0293 

* HDBT 
Appendix U, Exhibit 2 

U2-11 

15 0.0000 0.0392 0.1078 0.0784 0.0392 0.0686 0.0196 0.1961 0.0980 0.0392 

 0.0490 0.0196 0.0196 0.0098 0.0196 0.0000 0.0196 0.0098 0.0098 0.0196 

 0.0098 0.0784 0.0490 0.0000 0.0000 

* MC 

16 0.0005 0.0984 0.1081 0.0942 0.0741 0.0577 0.0549 0.0472 0.0387 0.0364 

 0.0263 0.3635 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 

 0.0000 0.0000 0.0000 0.0000 0.0000 
Appendix U, Exhibit 2 

U2-12 

REG DIST 

* 

* The file REGDATA.D contains the default MOBILE6 values for the distribution of 

* vehicles by age for July of any calendar year. There are sixteeen (16) 

* sets of values representing 16 combined gasoline/diesel vehicle class 

* distributions. These distributions are split for gasoline and diesel 

* using the separate input (or default) values for diesel sales fractions. 

* Each distribution contains 25 values which represent the fraction of 

* all vehicles in that class (gasoline and diesel) of that age in July. 

* The first number is for age 1 (calendar year minus model year plus one) 

* and the last number is for age 25. The last age includes all vehicles 

* of age 25 or older. The first number in each distribution is an integer 

* which indicates which of the 16 vehicle classes are represented by the 

* distribution. The sixteen vehicle classes are: 

* 

* 1 LDV Light-Duty Vehicles (Passenger Cars) 

* 2 LDT1 Light-Duty Trucks 1 (0-6,000 lbs. GVWR, 0-3750 lbs. LVW) 

* 3 LDT2 Light Duty Trucks 2 (0-6,001 lbs. GVWR, 3751-5750 lbs. LVW) 

* 4 LDT3 Light Duty Trucks 3 (6,001-8500 lbs. GVWR, 0-3750 lbs. LVW) 

* 5 LDT4 Light Duty Trucks 4 (6,001-8500 lbs. GVWR, 3751-5750 lbs. LVW) 

* 6 HDV2B Class 2b Heavy Duty Vehicles (8501-10,000 lbs. GVWR) 

* 7 HDV3 Class 3 Heavy Duty Vehicles (10,001-14,000 lbs. GVWR) 

* 8 HDV4 Class 4 Heavy Duty Vehicles (14,001-16,000 lbs. GVWR) 

* 9 HDV5 Class 5 Heavy Duty Vehicles (16,001-19,500 lbs. GVWR) 

* 10 HDV6 Class 6 Heavy Duty Vehicles (19,501-26,000 lbs. GVWR) 

* 11 HDV7 Class 7 Heavy Duty Vehicles (26,001-33,000 lbs. GVWR) 

* 12 HDV8A Class 8a Heavy Duty Vehicles (33,001-60,000 lbs. GVWR) 

* 13 HDV8B Class 8b Heavy Duty Vehicles (>60,000 lbs. GVWR) 

* 14 HDBS School Busses 

* 15 HDBT Transit and Urban Busses 

* 16 MC Motorcycles (All) 

* 

* The 25 age values are arranged in two rows of 10 values followed by a row 

* with the last 5 values. Comments (such as this one) are indicated by 

* an asterisk in the first column. Empty rows are ignored. Values are 

* read "free format," meaning any number may appear in any row with as 

* many characters as needed (including a decimal) as long as 25 values 

* follow the initial integer value separated by a space. 

* 

* If all 16 vehicle classes do not need to be altered from the default 

* values, then only the vehicle classes that need to be changed need to 

* be included in this file. The order in which the vehicle classes are 

* read does not matter, however each vehicle class set must contain 25 

* values and be in the proper age order. 

* ___________________________________________________________________________ 

* 

* This file specifies the local registration distribution by age 

* (MOBILE6 defaults for heavy-heavy-duties) for the 139 Georgia counties 

* outside the 20-county Atlanta nonattainment area. Sources of registration 

* data: R. L. Polk & Co.'s National Vehicle Population Profile (R) as of 

* October 2002 and R. L. Polk & Co.'s TIPNet (R) as of March 2003. 

* 

* LDV 

1 0.0102 0.0408 0.0473 0.0575 0.0571 0.0543 0.0601 0.0588 0.0718 0.0625 

 0.0608 0.0535 0.0487 0.0447 0.0450 0.0393 0.0325 0.0277 0.0249 0.0195 

 0.0120 0.0072 0.0064 0.0056 0.0515 

* LDT1 

2 0.0166 0.0785 0.0744 0.0845 0.0689 0.0715 0.0618 0.0607 0.0619 0.0600 

 0.0523 0.0379 0.0360 0.0258 0.0325 0.0314 0.0282 0.0240 0.0175 0.0142 

 0.0085 0.0052 0.0033 0.0032 0.0412 

* LDT2 
Appendix U, Exhibit 2 

U2-13 

3 0.0007 0.0022 0.0129 0.0161 0.0191 0.0483 0.0713 0.0001 0.0135 0.0354 

 0.0507 0.0470 0.0470 0.0741 0.0782 0.0797 0.0504 0.0739 0.0708 0.0643 

 0.0486 0.0440 0.0519 0.0000 0.0000 

* LDT3 

4 0.0383 0.0965 0.0928 0.0861 0.0941 0.0614 0.0683 0.0709 0.0781 0.0609 

 0.0343 0.0260 0.0157 0.0182 0.0210 0.0193 0.0200 0.0251 0.0249 0.0202 

 0.0131 0.0083 0.0064 0.0000 0.0001 

* LDT4 

5 0.0106 0.0270 0.0422 0.0560 0.0592 0.0440 0.0484 0.0515 0.0786 0.0735 

 0.0624 0.0557 0.0449 0.0593 0.0679 0.0558 0.0305 0.0322 0.0297 0.0326 

 0.0213 0.0105 0.0062 0.0000 0.0000 

* HDV2B 

6 0.0343 0.0568 0.0680 0.0751 0.0829 0.0274 0.0751 0.0576 0.0554 0.0462 

 0.0415 0.0317 0.0238 0.0279 0.0421 0.0444 0.0306 0.0432 0.0415 0.0358 

 0.0213 0.0184 0.0167 0.0004 0.0017 

* HDV3 

7 0.0282 0.0657 0.0937 0.0837 0.1077 0.0329 0.0503 0.0423 0.0555 0.0430 

 0.0382 0.0309 0.0263 0.0332 0.0361 0.0368 0.0350 0.0426 0.0295 0.0263 

 0.0127 0.0102 0.0068 0.0022 0.0302 

* HDV4 

8 0.0128 0.0392 0.0491 0.0741 0.0799 0.0424 0.0780 0.0442 0.0756 0.0521 

 0.0483 0.0348 0.0342 0.0455 0.0654 0.0577 0.0308 0.0174 0.0258 0.0251 

 0.0132 0.0110 0.0055 0.0000 0.0381 

* HDV5 

9 0.0226 0.0386 0.0424 0.0636 0.0905 0.0203 0.0606 0.0476 0.0438 0.0267 

 0.0161 0.0180 0.0121 0.0152 0.0074 0.0122 0.0128 0.0087 0.0105 0.0121 

 0.0112 0.0079 0.0128 0.0015 0.3850 

* HDV6 

10 0.0096 0.0173 0.0199 0.0458 0.0461 0.0361 0.0272 0.0257 0.0384 0.0239 

 0.0217 0.0218 0.0195 0.0194 0.0191 0.0260 0.0257 0.0274 0.0272 0.0240 

 0.0163 0.0171 0.0144 0.0121 0.4183 

* HDV7 

11 0.0121 0.0201 0.0294 0.0442 0.0409 0.0350 0.0334 0.0387 0.0588 0.0382 

 0.0326 0.0343 0.0407 0.0535 0.0462 0.0548 0.0520 0.0523 0.0549 0.0492 

 0.0223 0.0218 0.0285 0.0390 0.0673 

* HDV8A 

12 0.0243 0.0195 0.0348 0.0699 0.0613 0.0632 0.0526 0.0697 0.0814 0.0646 

 0.0587 0.0396 0.0345 0.0390 0.0495 0.0452 0.0377 0.0292 0.0311 0.0257 

 0.0115 0.0094 0.0110 0.0087 0.0278 

* HDV8B 

*13 0.0190 0.0208 0.0377 0.0583 0.0613 0.0485 0.0453 0.0485 0.0576 0.0426 

* 0.0352 0.0187 0.0283 0.0214 0.0348 0.0458 0.0335 0.0315 0.0355 0.0350 

* 0.0146 0.0139 0.0182 0.0275 0.1662 

* HDBS 

14 0.0340 0.0471 0.0634 0.0589 0.0528 0.0491 0.0649 0.0528 0.0692 0.0343 

 0.0614 0.0534 0.0691 0.0693 0.0346 0.0534 0.0157 0.0172 0.0161 0.0131 

 0.0132 0.0094 0.0091 0.0093 0.0295 

* HDBT 

15 0.0677 0.0501 0.0265 0.0383 0.0427 0.0324 0.0619 0.0574 0.0236 0.0353 

 0.0471 0.0295 0.0471 0.0339 0.0619 0.0412 0.0353 0.0236 0.0353 0.0574 

 0.0442 0.0545 0.0530 0.0000 0.0000 
Appendix U, Exhibit 2 

U2-14 

* MC 

16 0.0006 0.0906 0.1056 0.0867 0.0727 0.0544 0.0499 0.0490 0.0406 0.0364 

 0.0310 0.3825 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 

 0.0000 0.0000 0.0000 0.0000 0.0000 
Appendix U, Exhibit 3 

Emissions Modeling Assumptions 

Used to Develop Motor Vehicle Emission Budgets for the 

Atlanta Eight-Hour Ozone 15% Reasonable Further Progress Plan 

and Attainment Demonstration

On April 30, 2004, the United States Environmental Protection Agency designated 20 

counties within the metropolitan Atlanta area as a "marginal" nonattainment under the 

eight-hour ozone standard. The eight-hour ozone nonattainment area encompasses the 

previous 13-county one-hour ozone nonattainment area plus seven additional "ring" 

counties: Barrow, Bartow, Carroll, Hall, Newton, Spalding, and Walton. With an 

attainment deadline of June 15, 2007, marginal 8-hour ozone areas were required to attain 

the National Ambient Air Quality Standard (NAAQS) by the 2006 ozone season. 

Because monitoring data from the 2006 ozone season indicated that Atlanta had not 

attained the NAAQS, the area was reclassified to "moderate"). Regional emissions 

inventories for the 20-county eight-hour ozone nonattainment area are needed to develop 

Motor Vehicle Emission Budgets (MVEB) for NOx and VOC as part of the State 

Implementation Plan (SIP) revisions that will demonstrate reasonable further progress 

towards attainment and modeled attainment of the eight-hour ozone standard in Atlanta. 

In ozone nonattainment areas with air quality classified as "moderate" or worse, the 

reasonable further progress (RFP) requirement established in Section 182(b) of the CAA 

prescribes emission reductions from the baseline totaling 15% within six years of the 

base year (i.e., by the end of 2008 for the 8-hour ozone NAAQS). MVEB are being 

established for the year 2008, the RFP milestone year. Separate MVEB are being 

established for 2009, the last full ozone season before the June 15, 2010, "maximum 

attainment date" for a moderate ozone area. Below is a detailed listing of the procedures 

and planning assumptions that were used for the regional emissions inventories to support 

MVEB development. This document was submitted to the Interagency Consultation 

Group, in accordance with Section 93.105(b) of the Transportation Conformity Rule and 

Sections 106(g) and 106(h) of Georgia's transportation conformity SIP, all of which 

require interagency consultation for SIP development, on October 28, 2008. 

Section 1: General Methods and Assumptions 

• Regional emissions inventories completed to establish MVEB for Atlanta Eight-Hour 

Ozone 15% RFP Plan and Attainment Demonstration 

• Emissions Modeling Methodology 

o Eight-Hour Ozone Nonattainment Area: 

 Existing ARC link-level travel demand and emissions modeling process for 

20-county Atlanta ozone nonattainment area 

U3-1 
Section 2: Travel Demand Modeling Assumptions 

• Calibration Year: 2000 

• Project Listing: 

o As approved in Envision6 2030 RTP and 2008-2013 TIP; adopted by the ARC 

Board September 26, 2007; and received a positive conformity determination 

from USDOT October 10, 2007 

o As approved in 2030 LRTP and 2008-2013 TIP; adopted by GHMPO Board 

August 14, 2007; and received a positive conformity determination from USDOT 

October 10, 2007 

o Project coding for network years 2005 and 2010 reviewed by state and local 

project sponsors in March and April 2007 as part of Envision6 2030 RTP/FY 

2008-2013 TIP development 

 Year 2008 and 2009 networks needed for budget inventories derived from 

2010 travel model network 

• Travel demand model refinements implemented as part of model expansion to 20 

counties, from the previous 13-county platform: 

o Mode choice model updated to improve performance of suburban intra-county 

trips 

o Attraction share model incorporated into four-step modeling process 

o New commercial vehicle and truck model developed to improve traffic 

assignment for both passenger vehicles and truck traffic 

• Demographic Data: See "Demographic Data Used to Develop Motor Vehicle 

Emissions Budgets for the Atlanta Attainment Demonstrations" 

• Speed Data: Free-flow Speed by Area Type and Facility Type 

Note: Within the ARC travel demand and emission modeling process, free flow 

speeds are adjusted to reflect the increase in delay and travel time on a roadway 

segment as traffic volumes build and congestion levels increase. Link-level 

congested flow speeds are used to estimate mobile source emissions, consistent with 

the requirements of Sections 93.122(b)(1)(iv) and 93.122(b)(2) of the Transportation 

Conformity Rule. 

U3-2 
Free Flow Speed by Area Type and Facility Type 

Area Type

 Facility Type 

Urban Very 

High Density

Urban High 

Density 

Urban 

Medium 

Density

Urban 

Low 

Density Suburban Exurban Rural 

Metered 

Ramps 

0 Zone Centroid Connectors 7 11 11 11 11 14 14 

1 

Interstate / Freeway Free 

Flow 55 58 58 61 61 63 65 

2 Parkway 50 50 55 55 57 60 60 

3 HOV Buffer Separated 55 58 58 61 61 63 65 

4 HOV Barrier Separated 55 58 58 61 61 63 65 

5 

High Speed Ramp / CD 

Road 50 50 55 55 57 60 60 15 

6 Medium Speed Ramp 50 50 50 50 50 50 50 10 

7 Low Speed Ramp 40 40 40 40 40 40 40 10 

8 Loop Ramp 30 30 30 30 30 30 30 10 

9 Off Ramp w/ Intersection 25 25 25 25 25 25 25 

10 On Ramp w/ Intersection 40 40 40 40 40 40 40 5 

11 Expressway 40 42 45 48 52 55 60 

12 Principal Arterial - Class I 26 30 33 36 42 46 55 

13 Principal Arterial - Class II 24 27 30 34 40 44 48 

14 Minor Arterial - Class I 22 25 28 31 38 42 45 

15 Minor Arterial - Class II 20 23 26 29 34 38 42 

16 HOV - Arterial (all classes) 20 27 30 33 36 39 42 

17 Major Collector 18 22 25 28 31 34 38 

18 Minor Collector 15 18 21 24 27 30 35 

19 

Planned Ramps w/ 

Intersections 30 30 30 30 30 30 30 5 

20 Planned Directional Ramps 45 45 45 45 45 45 45 10 

• Transit Modeling 

o Model recalibrated to 2000 transit ridership estimates, provided by transit 

operators 

o Reflects results from Transit On Board Survey 

o Routes updated to reflect current operating plans 

o Transit mode split is estimated using the mode choice model 

 Estimates individual modal trips from the person trip movements developed in 

the trip distribution model. 

 Composed of three nested logit models: 

• Home based work trips, which includes home based university trips; 

• Home based other trips, which include home based other, home based 

shopping and home based grade school; and 

• Non-home based trips. 

 The mode choice models is organized in terms of seven characteristics: 

• Mathematical structure; 

• Trip purposes and choice sets; 

• Limitations on choice sets; 

• Analysis of transit access; 

• Treatment of HOV lanes; 

U3-3 
• Stratification by income groups; and 

• Analysis of alternative transit paths. 

o Transit Fare Modeling 

 Fare structure and operating plans supplied by the local transit operators 

• Fares remain constant over time, across all network years 

• Fares reflect current transit operating plans 

 Transit fare structure uses a fare matrix on a zone to zone level with a 

universal fare structure (flat fare) for all bus and rail lines 

• Changes to the existing fare structure and service frequency are coded 

directly into the model 

• Current fare values in the model are weighted according to the percentage 

of riders using a discounted fare pass; changes to these assumptions can be 

incorporated directly into the model 

• Peak and off-peak fares are equivalent 

Section 3: Emissions Modeling Assumptions 

• Emission Factor Model: MOBILE6.2.03 

• MOBILE6.2.03 Inputs (13-county portion) 

o Average hourly temperature, humidity, and average barometric pressure for the 10 

highest ozone days during 2000-2002 

o Stage II refueling 

 Started in 1992 

 Three phase in years 

 81% efficiency 

o Anti-tampering program 

 Started in 1982 

 Covers model years 1975 – 1995 

 All LDG vehicle types are covered 

 Annual program 

 97% compliance 

 Catalyst removal only 

o I/M Program 

 Exhaust and Evaporative (OBD and gas cap pressure test) for 1996 and newer 

vehicles 

• Began in 1982 

• Annual inspection required 

• Computerized test and repair OBD – Exhaust 

• Computerized test and repair OBD & GC - Evaporative 

• Applies to all LDG vehicle types 

• Three year grace period 

• 3% waiver rate for all vehicles – Exhaust test 

• 0% waiver rate for all vehicles – Evaporative test 

• 97% compliance 

U3-4 
 Exhaust and Evaporative test for 1975 – 1995 vehicles 

• Began in 1982 

• Annual inspection required 

• Computerized test and repair ASM 2525/5015 Phase-in – Exhaust 

• Computerized test and repair GC – Evaporative 

• Applies to all LDG vehicle types 

• 3% waiver rate for all vehicles – Exhaust 

• 0% waiver rate for all vehicles – Evaporative 

• 97% compliance 

• 25 year and older model years are exempt 

o Fuel27

 Low Sulfur, Low RVP Georgia Gasoline Phase 2 

• 100% market share of 10% ethanol-blend gasoline (E10) assumed 

• volatility waiver for E10 allows 8.0 psi RVP 

o 2002 regional fleet age distribution 

 Derived from R.L. Polk & Co. registration data for 13-county area 

 Applied to 15 of the 16 MOBILE6.2.03 composite vehicle classifications - 

LDV, LDT1, LDT2, LDT3, LDT4, HDV2B, HDV3, HDV4, HDV5, HDV6, 

HDV7, HDV8A, HDBS, HDBT, MC 

• Default for HDV8B 

o Default VMT fractions 

• MOBILE6.2.03 Inputs (7-county portion) 

o Same temperature, humidity, and barometric pressure inputs as 13-county area 

o No Stage II refueling 

o No anti-tampering program 

o No I/M program 

o Fuel 

 Same as 13-county area 

o 2002 regional fleet age distribution 

 Derived from R.L. Polk & Co. registration data for 7-county area 

 Applied to 15 of the 16 MOBILE6.2.03 composite vehicle classifications - 

LDV, LDT1, LDT2, LDT3, LDT4, HDV2B, HDV3, HDV4, HDV5, HDV6, 

HDV7, HDV8A, HDBS, HDBT, MC 

• Default for HDV8B 

o Default VMT fractions 

• VMT adjustment factors 

o Adjusts link-level VMT produced by travel model for ozone precursor emissions 

modeling: 

 

U3-5 

27 In 2002, Georgia's two-phase gasoline sulfur control program limited average sulfur in gasoline sold in 

the 13-county Atlanta area and in 12 surrounding counties to 150 parts per million (ppm). In addition, 

there is a seasonal (June 1 to September 15) 7.0 pounds per square inch (psi) Reid vapor pressure (RVP) 

cap on gasoline sold in this Phase 1 area. In 2003, Phase 2 of Georgia's gasoline rule reduced average 

sulfur to 30 ppm and added 20 additional counties outside the 20-county ozone nonattainment area to the 

sulfur and RVP control program. 
 HPMS adjustment in base year of calibration, year 2000, in accordance with 

Section 93.122(b)(3) of the Transportation Conformity Rule which 

recommends that HPMS adjustment factors be developed to reconcile travel 

model estimates of VMT in base year of calibration to HPMS estimates for 

the same period28 

 Summer (seasonal) adjustment to convert from average annual VMT to 

summer-season VMT29

 Factors applied to VMT estimates generated by ARC travel demand model for 

13-county and 7-county portions of 20-county nonattainment area, separately 

VMT Adjustment Factors – 13 County Portion

Functional Class Name Factor 

Rural Interstate 0.67 

Rural Prin. Arterial 1.02 

Rural Min. Arterial 1.16 

Rural Major Collector 0.88 

Rural Minor Collector 1.07 

Rural Local 0.64 

Urb. Interstate 1.05 

Urb. Other Fwy 2.44 

Urb. Prin. Arterial 0.67 

Urb. Min. Arterial 1.21 

Urbanized Collector 1.21 

Urbanized Local 0.95 

VMT Adjustment Factors – 7 County Portion

Functional Class Name Factor 

Rural Interstate 0.89 

Rural Prin. Arterial 0.99 

Rural Min. Arterial 0.98 

Rural Major Collector 1.81 

Rural Minor Collector 1.81 

Rural Local 1.10 

Urb. Interstate 0.86 

Urb. Other Fwy 0.85 

Urb. Prin. Arterial 0.97 

Urb. Min. Arterial 0.96 

Urbanized Collector 1.80 

Urbanized Local 1.06 

• Off-Model Calculations 

o The Senior I/M Exemption emissions debit calculated for 2002 was considered 

conservatively high and was also added to the 2008 and 2009 budget year 

inventories

 

28 40 CFR Part 93.122(b)(3) 

29 Procedures for Emission Inventory Preparation, Volume IV: Mobile Sources, Section 3.4.2.6, EPA420-

R-92-009, USEPA Office of Air and Radiation, Office of Mobile Sources, 1992. 

U3-6 
Appendix U, Exhibit 4 

Demographic Data 

Used to Develop Motor Vehicle Emissions Budgets for the 

Atlanta Attainment Demonstrations 

ARC periodically revises its population and employment forecasts based on best 

available current information. Each revision is a two-step process. First, new region-level 

forecasts are produced. These then become region-level controls for census tract and 

traffic analysis zone (TAZ) forecasts. 

The most current region-level control forecasts were completed in 2006. The 

accompanying table summarizes the new population and employment controls for the 

enlarged, 20-county study area. 

ARC staff were assisted in the development of these forecasts by a Technical Advisory 

Committee of local experts on the Atlanta Regional Economy. Chair of the Committee 

was Donald Ratajczak, Professor Emeritus, Georgia State University, and former Chair of 

the GSU Economic Forecasting Center. The committee recommended the final forecasts 

for use by the Commission. 

The second step in the forecasting process uses mathematical models to disaggregate the 

region-level control forecasts to the census tract and TAZ level. TAZs are subdivisions of 

census tracts. 

The DRAM/EMPAL models used to disaggregate the regional controls are iterative over 

a 5-year time period. Starting with the 2000 base, each successive 5-year forecast 

becomes the base for the next. First, the Cube/TP+ model analyzes base year traffic 

patterns and produces accessibility measures within the 20-county forecast area. Then, 

the DRAM/EMPAL models use that accessibility measure plus information on base-year 

population, employment and land use distributions to develop tract-level forecasts of 

those variables five years in the future. A Zonal Allocation Procedure is then used to split 

each tract-level forecast into the TAZs. These TAZ forecasts then become the input used 

by the Cube/TP+ model to produce the accessibility measures that drive the next 

iteration. 

All these models are carefully calibrated based on the best and most current data 

available. Data used in the current effort include 2000 United States Census results, ARC 

estimates of employment by industry for tracts and TAZs, national forecasts of 

employment and population produced by Economy.Com, employment estimates and 

forecasts produced by the Georgia Department of Labor, results of ARC travel surveys 

including the SMARTRAQ household travel survey, transit on-board survey, Hartsfield 

air passenger survey, travel time studies, speed studies, and others. Highway projects and 

the schedule for their completion (primary inputs to the Cube/TP+ model) are developed 

as part of an extensive discussion between ARC staff, local planners, Georgia 

Department of Transportation and various federal agencies. 

U4-1 
The expansion of the study-area from 13 to 20 counties required extensive effort to 

develop the modeling database for the 7 new counties. This expansion was expected, so 

in 2001 ARC produced year 2000 employment estimates by census tract for 12 

nonmember counties in addition to those for its 10 member counties. Land-use data for 

the additional counties was produced using aerial photography taken in 2000. Population 

data for these counties were compiled from 2000 Census results. ARC’s Cube/TP+ travel 

demand model was expanded to cover the new study area and was used to produce the 

year 2000 travel-cost estimates required to calibrate these models. 

ARC also produced tract-level 2005 estimates of population and employment for the 20-

county study area. These estimates supplemented the first iteration of the 

DRAM/EMPAL model. Development of the 2005 estimates and of the year 2000 

calibration database for the non-member counties was coordinated with the affected 

county governments and the Regional Development Centers of which they are members. 

Adjustments are made to the ARC forecasts to account for expected changes that would 

not be apparent from historical data. Some, like expected construction of a new highway 

or the restriction of development in a watershed area, are accounted for directly in the 

models. Others such as the completion of a major development project (Atlantic Station, 

for example) are incorporated as adjustments to the model output. 

The forecasts were used as part of the Envision6 RTP/FY 2008-2013 TIP, adopted by the 

ARC Board on September 26, 2007. 

U4-2 
U4-3 
U4-4 

 20-County Regional Control Forecasts 

Year Total Population Total Employment

1990 3,054,230 1,954,801

1995 3,575,441 2,295,762

2000 4,228,400 2,800,657

2005 4,791,000 2,920,855

2010 5,095,900 3,231,882

2015 5,499,600 3,601,467

2020 5,923,800 3,986,191

2025 6,382,800 4,406,078

2030 6,972,200 4,887,617

2035 7,698,700 5,322,247

Notes: 

1. Population for 1990 and 2000 are U. S Census counts. Population for 1995 and 

2005 are estimates produced by the Atlanta Regional Commission. 

2. Employment for 1990, 1995 and 2000 are estimates by the U. S. Bureau of 

Economic Analysis. 

3. The employment shown in this table will differ from that in the small area 

forecasts because this series includes proprietors. Small area data on proprietors is 

not available. 
Appendix U, Exhibit 6 

U5-1 

* 

* 7-1-09, 13 nonattainment counties, '02 reg. dist. (default for Class 8b), 

default VMT mix (09ar13e2.in) 

* 

MOBILE6 INPUT FILE : 

 

POLLUTANTS : HC CO NOx 

RUN DATA 

* next lines show average hourly temp. for 10 highest Atlanta ozone days 2000-

2002 

HOURLY TEMPERATURES: 74 77 81 84 86 88 90 91 92 92 91 90 

 88 86 83 82 80 78 76 75 74 73 72 72 

* Reid vapor pressure of 7.0 psi is a requirement for Georgia gasoline, Phases 

1 and 2 

FUEL RVP : 7.0 

* the 2000 through 2002 sulfur levels below are for the 25-county (Phase 1) 

* Georgia gasoline control area (includes 13-county Atlanta nonattainment 

* area plus 12 other counties) 

FUEL PROGRAM : 4 

 150.0 150.0 150.0 90.0 30.0 30.0 30.0 30.0 

 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 

 1000.0 1000.0 1000.0 1000.0 150.0 150.0 87.0 87.0 

 80.0 80.0 80.0 80.0 80.0 80.0 80.0 80.0 

STAGE II REFUELING : 

92 3 81. 81. 

* According to section 2.8.9.3 of "User's Guide to MOBILE6.1 and MOBILE6.2: 

Mobile 

* Source Emission Factor Model" 

(http://www.epa.gov/otaq/models/mobile6/420r03010.pdf) 

* "All 1996 and newer model year vehicles are assumed to have negligible 

tampering 

* effects. As a result, there is no tampering reduction benefit associated 

with the 

* 1996 and newer vehicles." 

ANTI-TAMP PROG : 

82 75 95 22222 11111111 1 11 097. 12111111 

* The external data file "im-info.d" is for 2002 and later evaluation dates; 

* "iminfo-p.d" is identical to "im-info.d" but with phase-in ASM cutpoints 

I/M DESCRIPT FILE : iminfo-p.d 

REG DIST : 02regis2.d 

*______________________________________________________________________ 

* 

SCENARIO REC : arterial, Atlanta 13, 2009, 2.5 mph 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09ar13e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 

* next lines show average hourly rel. humidity for 10 highest Atlanta ozone 

days 2000-2002 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

* next line shows average daily barometric pressure for 10 highest Atlanta 

ozone days 2000-2002 

BAROMETRIC PRES : 28.99 

* % o2 mrkt 
Appendix U, Exhibit 6 

U5-2 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

* next line allows 1 psi increase to gasoline's Reid vapor pressure 

RVP OXY WAIVER : 2 

* the following information on conventional gasoline parameters 

* is from Table B-5 in EPA's staff white paper on "boutique fuels" 

* (EPA420-P-01-004, Oct 2001, http://www.epa.gov/otaq/regs/fuels/p01004.pdf) 

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

AVERAGE SPEED : 2.5 Arterial 0.0 100.0 0.0 0.0 

*______________________________________________________________________ 

* 

SCENARIO REC : arterial, Atlanta 13, 2009, 3 mph 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09ar13e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

BAROMETRIC PRES : 28.99 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

RVP OXY WAIVER : 2 

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

AVERAGE SPEED : 3 Arterial 0.0 100.0 0.0 0.0 

*______________________________________________________________________ 

* 

[scenarios for 4 mph through 64 mph not shown] 

*______________________________________________________________________ 

* 

SCENARIO REC : arterial, Atlanta 13, 2009, 65 mph 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09ar13e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

BAROMETRIC PRES : 28.99 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

RVP OXY WAIVER : 2 

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

AVERAGE SPEED : 65 Arterial 0.0 100.0 0.0 0.0 

*______________________________________________________________________ 

* 
Appendix U, Exhibit 6 

U5-3 

SCENARIO REC : local, Atlanta 13, 2009, no speed input 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09ar13e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

BAROMETRIC PRES : 28.99 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

RVP OXY WAIVER : 2 

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

* 

* Note that 12.9 is the default MOBILE6 average speed for local streets. 

AVERAGE SPEED : 12.9 local 

*______________________________________________________________________ 

* 

SCENARIO REC : ramps, Atlanta 13, 2009, no speed input 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09ar13e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

BAROMETRIC PRES : 28.99 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

RVP OXY WAIVER : 2 

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

* 

* Note that 34.6 is the default MOBILE6 average speed for ramps. 

AVERAGE SPEED : 34.6 ramp 

END OF RUN 
Appendix U, Exhibit 6 

U5-4 

* 

* 7-1-09, 7 nonattainment counties, '02 reg. dist. (default for Class 8b), 

default VMT mix (09art7e2.in) 

* 

MOBILE6 INPUT FILE : 

 

POLLUTANTS : HC CO NOx 

RUN DATA 

* next lines show average hourly temp. for 10 highest Atlanta ozone days 2000-

2002 

HOURLY TEMPERATURES: 74 77 81 84 86 88 90 91 92 92 91 90 

 88 86 83 82 80 78 76 75 74 73 72 72 

* Reid vapor pressure of 7.0 psi is a requirement for Georgia gasoline, Phases 

1 and 2 

FUEL RVP : 7.0 

[redundant comments not shown] 

FUEL PROGRAM : 4 

 150.0 150.0 150.0 90.0 30.0 30.0 30.0 30.0 

 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 

 1000.0 1000.0 1000.0 1000.0 150.0 150.0 87.0 87.0 

 80.0 80.0 80.0 80.0 80.0 80.0 80.0 80.0 

REG DIST : 02atl_7.d 

*______________________________________________________________________ 

* 

SCENARIO REC : arterial, Atlanta 7, 2009, 2.5 mph 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09art7e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 

* next lines show average hourly rel. humidity for 10 highest Atlanta ozone 

days 2000-2002 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

* next line shows average daily barometric pressure for 10 highest Atlanta 

ozone days 2000-2002 

BAROMETRIC PRES : 28.99 

* % o2 mrkt 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

* next line allows 1 psi increase to gasoline's Reid vapor pressure 

RVP OXY WAIVER : 2 

[redundant comments not shown]

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

AVERAGE SPEED : 2.5 Arterial 0.0 100.0 0.0 0.0 

*______________________________________________________________________ 

* 

SCENARIO REC : arterial, Atlanta 7, 2009, 3 mph 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09art7e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 
Appendix U, Exhibit 6 

U5-5 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

BAROMETRIC PRES : 28.99 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

RVP OXY WAIVER : 2 

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

AVERAGE SPEED : 3 Arterial 0.0 100.0 0.0 0.0 

*______________________________________________________________________ 

* 

[scenarios for 4 mph through 64 mph not shown]

*______________________________________________________________________ 

* 

SCENARIO REC : arterial, Atlanta 7, 2009, 65 mph 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09art7e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

BAROMETRIC PRES : 28.99 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

RVP OXY WAIVER : 2 

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

AVERAGE SPEED : 65 Arterial 0.0 100.0 0.0 0.0 

*______________________________________________________________________ 

* 

SCENARIO REC : local, Atlanta 7, 2009, no speed input 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09art7e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

BAROMETRIC PRES : 28.99 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

RVP OXY WAIVER : 2 

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

* 

* Note that 12.9 is the default MOBILE6 average speed for local streets. 

AVERAGE SPEED : 12.9 local 

*______________________________________________________________________ 
Appendix U, Exhibit 6 

U5-6 

* 

SCENARIO REC : ramps, Atlanta 7, 2009, no speed input 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09art7e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

BAROMETRIC PRES : 28.99 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

RVP OXY WAIVER : 2 

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

* 

* Note that 34.6 is the default MOBILE6 average speed for ramps. 

AVERAGE SPEED : 34.6 ramp 

END OF RUN 
Appendix U, Exhibit 6 

U5-7 

* 

* 7-1-09, 13 nonattainment counties, '02 reg. dist. (default for Class 8b), 

default VMT mix (09fw13e2.in) 

* 

MOBILE6 INPUT FILE : 

 

POLLUTANTS : HC CO NOx 

RUN DATA 

* next lines show average hourly temp. for 10 highest Atlanta ozone days 2000-

2002 

HOURLY TEMPERATURES: 74 77 81 84 86 88 90 91 92 92 91 90 

 88 86 83 82 80 78 76 75 74 73 72 72 

* Reid vapor pressure of 7.0 psi is a requirement for Georgia gasoline, Phases 

1 and 2 

FUEL RVP : 7.0 

[redundant comments not shown]

FUEL PROGRAM : 4 

 150.0 150.0 150.0 90.0 30.0 30.0 30.0 30.0 

 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 

 1000.0 1000.0 1000.0 1000.0 150.0 150.0 87.0 87.0 

 80.0 80.0 80.0 80.0 80.0 80.0 80.0 80.0 

STAGE II REFUELING : 

92 3 81. 81. 

[redundant comments not shown]

ANTI-TAMP PROG : 

82 75 95 22222 11111111 1 11 097. 12111111 

* The external data file "im-info.d" is for 2002 and later evaluation dates; 

* "iminfo-p.d" is identical to "im-info.d" but with phase-in ASM cutpoints 

I/M DESCRIPT FILE : iminfo-p.d 

REG DIST : 02regis2.d 

*______________________________________________________________________ 

* 

SCENARIO REC : freeway, Atlanta 13, 2009, 2.5 mph 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09fw13e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 

* next lines show average hourly rel. humidity for 10 highest Atlanta ozone 

days 2000-2002 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

* next line shows average daily barometric pressure for 10 highest Atlanta 

ozone days 2000-2002 

BAROMETRIC PRES : 28.99 

* % o2 mrkt 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

* next line allows 1 psi increase to gasoline's Reid vapor pressure 

RVP OXY WAIVER : 2 

[redundant comments not shown]

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 
Appendix U, Exhibit 6 

U5-8 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

AVERAGE SPEED : 2.5 Non-Ramp 100.0 0.0 0.0 0.0 

*______________________________________________________________________ 

* 

SCENARIO REC : freeway, Atlanta 13, 2009, 3 mph 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09fw13e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

BAROMETRIC PRES : 28.99 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

RVP OXY WAIVER : 2 

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

AVERAGE SPEED : 3 Non-Ramp 100.0 0.0 0.0 0.0 

*______________________________________________________________________ 

* 

[scenarios for 4 mph through 64 mph not shown]

*______________________________________________________________________ 

* 

SCENARIO REC : freeway, Atlanta 13, 2009, 65 mph 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09fw13e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

BAROMETRIC PRES : 28.99 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

RVP OXY WAIVER : 2 

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

AVERAGE SPEED : 65 Non-Ramp 100.0 0.0 0.0 0.0 

END OF RUN 
Appendix U, Exhibit 6 

U5-9 

* 

* 7-1-09, 7 nonattainment counties, '02 reg. dist. (default for Class 8b), 

default VMT mix (09fwy7e2.in) 

* 

MOBILE6 INPUT FILE : 

 

POLLUTANTS : HC CO NOx 

RUN DATA 

* next lines show average hourly temp. for 10 highest Atlanta ozone days 2000-

2002 

HOURLY TEMPERATURES: 74 77 81 84 86 88 90 91 92 92 91 90 

 88 86 83 82 80 78 76 75 74 73 72 72 

* Reid vapor pressure of 7.0 psi is a requirement for Georgia gasoline, Phases 

1 and 2 

FUEL RVP : 7.0 

[redundant comments not shown] 

FUEL PROGRAM : 4 

 150.0 150.0 150.0 90.0 30.0 30.0 30.0 30.0 

 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 

 1000.0 1000.0 1000.0 1000.0 150.0 150.0 87.0 87.0 

 80.0 80.0 80.0 80.0 80.0 80.0 80.0 80.0 

REG DIST : 02atl_7.d 

*______________________________________________________________________ 

* 

SCENARIO REC : freeway, Atlanta 7, 2009, 2.5 mph 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09fwy7e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 

* next lines show average hourly rel. humidity for 10 highest Atlanta ozone 

days 2000-2002 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

* next line shows average daily barometric pressure for 10 highest Atlanta 

ozone days 2000-2002 

BAROMETRIC PRES : 28.99 

* % o2 mrkt 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

* next line allows 1 psi increase to gasoline's Reid vapor pressure 

RVP OXY WAIVER : 2 

[redundant comments not shown] 

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

AVERAGE SPEED : 2.5 Non-Ramp 100.0 0.0 0.0 0.0 

*______________________________________________________________________ 

* 

SCENARIO REC : freeway, Atlanta 7, 2009, 3 mph 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09fwy7e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 
Appendix U, Exhibit 6 

U5-10 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

BAROMETRIC PRES : 28.99 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

RVP OXY WAIVER : 2 

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

AVERAGE SPEED : 3 Non-Ramp 100.0 0.0 0.0 0.0 

*______________________________________________________________________ 

* 

[scenarios for 4 mph through 64 mph not shown] 

*______________________________________________________________________ 

* 

SCENARIO REC : freeway, Atlanta 7, 2009, 65 mph 

> July 1, 2009, '02 reg. dist. (default for Class 8b), default VMT mix 

(09fwy7e2.in) 

CALENDAR YEAR : 2009 

EVALUATION MONTH : 7 

RELATIVE HUMIDITY : 76 68 60 53 49 45 42 40 39 38 38 41 

 44 49 53 57 61 65 69 70 72 75 78 77 

BAROMETRIC PRES : 28.99 

OXYGENATE : MTBE 0.00 0.00 

 : ETBE 0.00 0.00 

 : ETOH 10.00 1.00 

 : TAME 0.00 0.00 

RVP OXY WAIVER : 2 

GAS AROMATIC% : 32.0 

GAS OLEFIN% : 13.0 

E200 : 41.0 

E300 : 83.0 

GAS BENZENE% : 1.5 

AVERAGE SPEED : 65 Non-Ramp 100.0 0.0 0.0 0.0 

END OF RUN 
Appendix U, Exhibit 6 

Effect Of Senior Exemption on 2002 Highway Mobile Source Emissions

During their 1996 session the Georgia General Assembly amended the Georgia Motor 

Vehicle Emission Inspection and Maintenance Act (O.C.G.A. Section 12-9, et seq), to 

exempt from emission testing those otherwise subject vehicles ten years old or older 

driven fewer than 5,000 miles per year and owned by persons 65 years old or older. 

The actual numbers of vehicles that received senior citizen exemptions from Georgia's 

inspection and maintenance (I/M) program waiver centers in 2002 are shown in the table 

below (source: Appendix I, Detailed List of Waivers Processed, from 2002 Annual 

Operations Report for Georgia's Enhanced Inspection and Maintenance Program, July 

30, 2003): 

AGE VEHICLES

10 years 1,629 

11 years 2,120 

12 years 2,239 

13 years 2,630 

14 years 2,496 

15 years 2,350 

16 years 2,369 

17 years 2,227 

18 years 1,708 

19 years 1,111 

20 years 669 

21 years 586 

22 years 496 

23 years 833 

24 years 794 

25 years 44 

U6-1 
2002 NOx Credit Loss 

MOBILE6.2 emission factors for calculating the 2002 NOx credit loss from these 

exempted vehicles were determined in the following manner. Six combined highway 

mobile source control strategies were modeled: 

• enhanced I/M in all 13 Atlanta ozone nonattainment area counties; 

• the Federal Motor Vehicle Control Program, including Tier 1 and Tier 2 tailpipe 

standards; 

• Stage II vapor recovery; 

• low-sulfur (150 parts per million, or ppm) and low Reid Vapor Pressure (7.0 pounds 

per square inch, or psi) gasoline; 

• the National Low Emission Vehicle (NLEV) program; and 

• technician training and certification). 

The enhanced I/M program is a decentralized annual hybrid with onboard diagnostics 

(OBD-II) system checks on 1996 and newer model year vehicles; and two-mode ASM 

tests on 25-year-old through 1995 model year vehicles. Anti-tampering inspections 

(checking for catalyst removal) are performed on 25-year-old through 1995 model year 

vehicles, and gas cap pressure tests are performed on all vehicles subject to inspection. 

• An overall 2002 highway mobile source NO inventory based on July 1, 2002, 

MOBILE6.2 emission factors with all controls in place (310,382,142 grams per day)

x

was divided by the total summer-adjusted 2002 VMT (122,754,275 miles) with a 

resulting overall grams-per-mile NOx emission factor of 2.528. 

• MOBILE6.2 runs with all subject vehicles receiving their appropriate test were 

performed to determine the speed that would result in a July 1, 2002, NO emission 

factor of 2.528 grams per mile: 38.58 miles per hour. 

x

• Two separate July 1, 2002, MOBILE6.2 runs, at 38.58 mph and with emissions 

calculated by model year, were made: one with hybrid I/M on 25-year-old and newer 

subject vehicles; the other with OBD-II system checks on 1996 and newer vehicles, 

with 1995 and older vehicles exempted. 

• Next, both sets (covered and exempt) of emission factors were separately multiplied 

by the VMT fractions,30 normalized to total 1.000, for the appropriate vehicle types 

(LDGV, LDGT12, LDGT34), and the three products were then added together to 

produce a single passenger vehicle emission factor for each exempted vehicle age. 

• The differences in the covered and exempt emission factors were then determined for 

each exempted vehicle age, these differences were multiplied by 4999, the maximum 

allowable yearly miles traveled by exempt vehicles, and that product was then 

 

30 An output of MOBILE6.2, the VMT (vehicle miles traveled) fraction is the fraction of total VMT 

traveled by each vehicle type. 

U6-2 
multiplied by the number of vehicles of that age to determine grams per year. Grams 

per year were converted to tons per day (907,180 grams per ton, 365 days per year) 

and the resulting NO reduction credit loss for 2002 was determined to be 0.03 ton 

per day. 

x

2002 VOC Credit Loss 

MOBILE6.2 emission factors for calculating the 2002 VOC credit loss from these 

exempted vehicles were determined in the following manner: 

• An overall 2002 highway mobile source VOC inventory based on July 1, 2002, 

MOBILE6.2 emission factors with all controls in place (158,026,372 grams per day) 

was divided by the total 2002 VMT (122,754,275 miles) with a resulting overall 

grams-per-mile VOC emission factor of 1.287. 

• MOBILE6.2 runs with all subject vehicles receiving their appropriate test were 

performed to determine the speed that would result in a July 1, 2002, VOC emission 

factor of 1.287 grams per mile: 30.6 miles per hour. 

• Two separate July 1, 2002, MOBILE6.2 runs, at 30.6 mph and with emissions 

calculated by model year, were made: one with hybrid I/M on 25-year-old and newer 

subject vehicles; the other with OBD-II system checks on 1996 and newer vehicles, 

with 1995 and older vehicles exempted. 

• Next, both sets (covered and exempt) of emission factors were separately multiplied 

by the VMT fractions, normalized to total 1.000, for the appropriate vehicle types 

(LDGV, LDGT12, LDGT34), and the three products were then added together to 

produce a single passenger vehicle emission factor for each exempted vehicle age. 

• The differences in the covered and exempt emission factors were then determined for 

each exempted vehicle age, these differences were multiplied by 4999, the maximum 

allowable yearly miles traveled by exempt vehicles, and that product was then 

multiplied by the number of vehicles of that age to determine grams per year. Grams 

per year were converted to tons per day (907,180 grams per ton, 365 days per year) 

and the resulting VOC reduction credit loss for 2002 was determined to be 0.05 

tons per day. 

U6-3 
U6-4