APPENDIX C ON ROAD MOBILE EMISSIONS INVENTORY DEVELOPMENT SAN ANTONIO EAC REGION ATTAINMENT DEMONSTRATION MARCH 2004 1 TECHNICAL NOTE Transportation Air Quality Technical Support Interagency Contract with Texas Commission on Environmental Quality TO: Mary McGarry Barber, Project Manager DATE: 12 June 2003 Texas Commission on Environmental Quality FROM: Dennis G. Perkinson, Ph. D., Martin E. Boardman and L. D. White Texas Transportation Institute SUBJECT: San Antonio Metropolitan Statistical Area On Road Mobile Source Modeling Emissions Inventories: 1999, 2007, and 2012 ( Umbrella Contract 3 60200 04: Task 01)  Review Draft INTRODUCTION This technical note documents the methods the Texas Transportation Institute ( TTI) used to develop 1999, 2007 and 2012 September day of week hourly on road mobile source emissions inventories ( EIs) for the four San Antonio Metropolitan Statistical Area ( SA/ MSA) counties. These EIs are for the four ozone episode days, September 17  20, 1999 ( a Friday, Saturday, Sunday, and Monday). The results are produced in the form of photochemical modelready input as well as in tabular summaries. This task is in support of the SA/ MSA Early Action Compact air quality analyses.

The four SA/ MSA counties are Bexar, Comal, Guadalupe, and Wilson. The emissions basis for each county may be distinguished as either link or virtual link. Emissions are estimated on a transportation network link basis for counties with travel demand models ( TDM) available ( Bexar). Emissions are estimated on a " virtual" link basis, or Highway Performance Monitoring System ( HPMS) functional class/ area type level, for counties without complete TDMs available ( Comal, Guadalupe, and Wilson).

The September 1999 episode day climate inputs were used for all evaluation years. Emissions estimates were developed based on September activity characteristic of the four day types: Weekday ( average Monday through Thursday), Friday, Saturday, and Sunday. 2 Emissions of volatile organic compounds ( VOC), carbon monoxide ( CO), and oxides of nitrogen ( NOx), are estimated for each county and day type on an hourly basis. Emissions are categorized by 28 vehicle types and 14 pollutant specific emissions types. Geographical coordinates are provided for the TDM network links.

Documented in this technical note are the methods relating to calculating inventory elements including vehicle miles traveled ( VMT), speeds, VMT mix, MOBILE6 emissions factors, and emissions estimates.

ACKNOWLEDGMENTS Chris Kite, with the Texas Commission on Environmental Quality ( TCEQ), and Martin Boardman and L. D. White, of TTI, contributed to the development of the MOBILE6 emissions factors input data parameter values. Boardman produced the MOBILE6 model set ups used, and performed the emissions factors analyses. Dennis Perkinson, Ph. D., of TTI, developed VMT growth factors, seasonal day of week VMT adjustment factors, hourly VMT allocation factors, and VMT mix. White processed TDM based VMT and modeled congested link speeds. Boardman processed HPMS based VMT and modeled congested virtual link speeds and performed the emissions estimations. Each member of the assigned TTI staff contributed to the quality assurance of the EI elements. Dr. Perkinson was the principle investigator for this project. This work was performed by TTI under contract to TCEQ. Mary McGarry Barber was the TCEQ project technical manager.

Deliverables Interim deliverables are an informal Technical Note ( a narrative in memorandum format that explains the task, the approaches used, and the findings) provided to the Project Manager in WordPerfect 6/ 7/ 8 format, and supported by electronic document files. All pertinent data are being submitted in specified electronic format. ( There is no FORTRAN source code or executable files developed under this task.) CD ROM is used to record the final data and supporting documentation. TTI is providing five copies of the final report. One of the copies is an unbound original suitable for copying. Electronic copies of all materials related to the task report to document results and conclusions ( e. g., data, work files, text files, etc.), or developed as work products under this contract are provided as requested by the TCEQ staff.

SUMMARY OF VMT AND EMISSIONS Table 1 through Table 4 summarize the SA/ MSA episode day emissions results by day type   Weekday, Friday, Saturday, and Sunday   respectively. Each table summarizes the daily total VMT, average speed ( 24 hour VMT divided by vehicle hours traveled [ VHT]), and VOC, CO, and NOx emissions ( tons) for each of the three analysis years by county and for the MSA.

The full results of the emissions analyses include: 1) individual county hourly link emissions files in the detailed disaggregate photochemical model preprocessor input format, and 2) summary EI data files with hourly and 24 hour county, vehicle type, and road type summaries of VMT, VHT, average speeds, and emissions estimates. These data files for each evaluation year and day type are provided on CD ROM. The data files are described in Appendix A.

Table 1 SA/ MSA September Weekday* On road Mobile Source VMT, Average Speed, and Emissions of VOC, CO, NOx ( Tons)

Year County VMT Speed VOC CO NOx Bexar 35,568,471 28.7 82.09 936.22 121.87 Comal 3,050,355 46.4 6.15 82.59 11.65 Guadalupe 2,745,268 45.9 5.57 74.59 10.47 Wilson 751,538 43.0 1.57 19.89 1.89 1999 Total 42,115,632 30.5 95.38 1,113.29 145.88 3 Bexar 40,117,156 30.5 45.48 523.43 69.10 Comal 3,795,030 45.3 3.85 50.33 7.07 Guadalupe 3,353,050 44.9 3.42 45.10 6.48 Wilson 941,667 42.9 0.98 12.23 1.34 2007 Total 48,206,902 32.3 53.73 631.09 83.99 Bexar 43,924,214 30.6 33.72 438.53 41.42 Comal 4,298,309 44.4 2.99 43.04 4.26 Guadalupe 3,736,338 44.3 2.61 38.23 3.90 Wilson 1,057,777 42.8 0.75 10.54 0.84 2012 Total 53,016,637 32.3 40.07 530.34 50.42 * Average Monday through Thursday activity, September 20, 1999 meteorology. 4 Table 2 SA/ MSA September Friday* On road Mobile Source VMT, Average Speed, and Emissions of VOC, CO, NOx ( Tons)

Year County VMT Speed VOC CO NOx Bexar 40,657,377 27.2 80.49 912.05 113.60 Comal 3,486,780 46.1 5.88 80.62 10.55 Guadalupe 3,138,043 45.7 5.32 73.02 9.55 Wilson 859,063 43.0 1.49 19.26 1.84 1999 Total 48,141,263 29.0 93.17 1,084.95 135.54 Bexar 45,856,541 29.0 44.43 527.84 64.96 Comal 4,337,999 44.7 3.67 50.70 6.46 Guadalupe 3,832,783 44.4 3.26 45.72 5.96 Wilson 1,076,395 42.8 0.93 12.29 1.30 2007 Total 55,103,717 30.8 52.29 636.56 78.68 Bexar 50,208,261 29.1 32.77 449.32 41.08 Comal 4,913,283 43.6 2.85 43.93 4.09 Guadalupe 4,270,909 43.8 2.48 39.39 3.77 Wilson 1,209,116 42.7 0.71 10.68 0.87 2012 Total 60,601,568 30.8 38.82 543.33 49.81 * Friday activity inputs, September 17, 1999 meteorology. 5 Table 3 SA/ MSA September Saturday* On road Mobile Source VMT, Average Speed, and Emissions of VOC, CO, NOx ( Tons)

Year County VMT Speed VOC CO NOx Bexar 31,589,162 32.4 51.71 640.23 70.13 Comal 2,709,089 47.0 3.96 58.00 6.50 Guadalupe 2,438,135 46.4 3.59 52.05 5.79 Wilson 667,458 43.2 1.00 13.58 1.20 1999 Total 37,403,844 34.0 60.27 763.87 83.62 Bexar 35,628,952 34.3 28.38 369.52 41.12 Comal 3,370,452 46.2 2.44 36.33 4.13 Guadalupe 2,977,919 45.8 2.17 32.24 3.68 Wilson 836,316 43.0 0.62 8.60 0.84 2007 Total 42,813,639 35.7 33.62 446.69 49.77 Bexar 39,010,090 34.3 20.94 315.42 26.52 Comal 3,817,425 45.7 1.88 31.70 2.69 Guadalupe 3,318,326 45.4 1.64 27.84 2.38 Wilson 939,435 42.9 0.47 7.49 0.57 2012 Total 47,085,276 35.8 24.94 382.46 32.16 * Saturday activity inputs, September 18, 1999 meteorology. 6 Table 4 SA/ MSA September Sunday* On road Mobile Source VMT, Average Speed, and Emissions of VOC, CO, NOx ( Tons)

Year County VMT Speed VOC CO NOx Bexar 24,986,143 34.3 41.96 534.32 50.22 Comal 2,142,813 47.3 3.27 48.34 4.55 Guadalupe 1,928,496 46.6 2.96 43.30 4.06 Wilson 527,941 43.2 0.83 11.27 0.90 1999 Total 29,585,394 35.7 49.02 637.24 59.73 Bexar 28,181,632 35.6 22.97 302.66 30.16 Comal 2,665,934 46.7 2.00 29.72 2.97 Guadalupe 2,355,450 46.1 1.77 26.25 2.63 Wilson 661,502 43.1 0.51 7.00 0.63 2007 Total 33,864,519 37.0 27.25 365.62 36.39 Bexar 30,856,026 35.7 16.95 257.52 19.93 Comal 3,019,477 46.4 1.54 25.92 2.00 Guadalupe 2,624,703 45.9 1.34 22.60 1.75 Wilson 743,066 43.1 0.39 6.08 0.44 2012 Total 37,243,272 37.1 20.23 312.11 24.12 * Sunday activity inputs, September 19, 1999 meteorology.

OVERVIEW OF METHODOLOGY To develop the emissions estimates by county, one of two methodologies were used depending on whether or not TDMs were available.

The main difference in the methodologies is in the level of disaggregation and the spatial allocation of the modeled VMT ( and speeds). For the TDM based counties, the method uses network links where emissions are estimated directionally at the link level for thousands of links where geographical coordinates are available. For counties without TDMs, emissions are estimated directionally at the HPMS functional classification and area type level for up to 21 functional class and area type combinations with no physical coordinates. The method for using HPMS for estimating on road mobile source emissions is detailed in the TTI document, " Near Nonattainment Emissions Inventories  HPMS Estimation Method/ Speed Model Refinement for Counties Without Link Based Travel Demand Models," June, 2000. 7 Aside from the differences in the methodologies associated with the VMT basis, the overall emissions estimation methods are basically analogous. The HPMS based emissions inventories may be thought of as linkbased for a virtual network consisting of larger and fewer links. For the purpose of further discussion in this report, the term " link" means both TDM network link and the HPMS " virtual" link ( or HPMS functional class, area type combination). For this analysis, emissions are estimated directionally, at the link level, by hour of day, for each county, for each of the four episode days.

Emissions factors are modeled with the MOBILE6 model ( October, 2002 release). The emissions factors are modeled by hour, MOBILE6 road type ( or drive cycle), 28 vehicle types, and speed. Texas Low Emissions Diesel ( LED) NOx benefits were modeled in the diesel vehicle class emissions factors via post processing. The speed sensitive freeway and arterial drive cycle emissions factors were applied   freeway emissions factors to freeway functional classifications, and arterial emissions factors to non freeway functional classifications ( except for network links coded as ramp). The non speed sensitive ramp emissions factors were applied to the TDM network ramp functional classification links.

The activity basis for the TDM counties are the Texas Department of Transportation ( TxDOT) TDM network equilibrium traffic assignments and trip information for 1999, 2007, and 2015 networks. Intermediate evaluation year ( i. e., 2012) VMT are estimated using growth rates with annual compounding based on the bounding assignment year VMT totals. For the HPMS based counties, the activity basis were the county 1999 historical HPMS VMT and 2007 and 2012 VMT forecasts. The HPMS county VMT forecasts were based on TxDOT HPMS county VMT data for 1990 through 2000 and population statistics and projections.

TxDOT Automatic Traffic Recorder ( ATR) based September day of week VMT factors were developed and applied to the county base VMT estimates for each evaluation year to produce the four day type specific, seasonally adjusted VMT estimates for each year. ATR based hourly travel fractions were developed for each of the four September day types and used to allocate the VMT for each county by hour of day. Directional split factors were applied to allocate the hourly VMT by peak and off peak direction. Based on the estimated hourly directional traffic volumes ( and capacities and freeflow speeds), fleet level, hourly, directional, average operational ( congested) speeds were estimated. The link congested speed is estimated as the link freeflow speed reduced by the " delay" estimate, which is a function of the link's volume to capacity ( v/ c) ratio.

Vehicle classification count data were used with vehicle registration data and MOBILE6 default gasoline/ diesel fractions to estimate 24 hour regional VMT mixes for apportioning fleetwide functional classification specific VMT for three functional classification groups to the 28 U. S. Environmental Protection Agency ( EPA) vehicle types. VMT mixes were estimated for each of the four day types. 8 Link emissions by vehicle type were calculated by hour for each county and evaluation year. For each evaluation year, there were four sets of hourly emissions files ( 24 files per day type) produced for each county. These hourly emissions files are formatted for photochemical grid model preprocessor input. The hourly emissions estimates include emission type sub components and total composites in grams of VOC, CO, and NOx. Tabular emissions summary files were also produced.

TTI previously developed a series of computer programs to produce detailed on road mobile source EIs. These computer programs were used to produce and/ or apply the EI elements ( adjusted operational hourly link VMT and speeds, VMT mix, and MOBILE6 emissions factors) to calculate the emissions estimates for this analysis. Appendix B describes these applications.

ESTIMATION OF VMT For each evaluation year and county, the main products of the VMT estimation process are estimates of seasonally adjusted, day type specific, HPMS consistent VMT by hour and direction for each link ( i. e. of the TDM networks for Bexar County and the HPMS " virtual network" for Comal, Guadalupe, and Wilson counties).

Growth estimates were developed and applied to estimate VMT for evaluation years where historical VMT estimates, or modeled VMT estimates were not available. Seasonal ( September), day type ( Weekday, Friday, Saturday, Sunday) adjustment factors and hourly travel factors were also developed and used to characterize the seasonal and day type travel on an hourly basis. The directional split factors were applied for estimating directional VMT ( or traffic volumes) for modeling directional congested link speeds ( discussed later).

Data Sources There are four traffic data sources used for developing the required adjustment factors and VMT estimates. These are the TDM data sets, ATR counts, HPMS VMT estimates, and vehicle classification counts ( used to estimate VMT mix). The TDMs are developed by TxDOT, and the other three data sets are collected by TxDOT on a formal and on going basis as part of the larger HPMS data collection program. U. S. Census and Texas State Data Center ( TSDC) county population statistics and projections were used in the HPMS VMT forecasts.

The latest San Antonio 1999, 2007, and 2015 TDM networks and trip matrices were used for this analysis. The networks and trip matrices were intitialy in TRANPLAN format. Using a series of steps, these networks and trip matrices were converted to TRANSCAD and a user equilibrium traffic assignment, with 24 iterations and 0.0001 convergence, was performed on each network. The zonal radii ( assumed intrazonal trip length) was also calculated for each network from the TRANSCAD format. Because the estimated intrazonal trips are not assigned to the network, the intrazonal trips and zonal radii were needed to estimate the intrazonal VMT. The TDM VMT are modeled as annual non summer weekday traffic ( ANSWT, or average Monday through Thursday traffic excluding the months of June through August). The San Antonio TDM network links are categorized by up to 15 functional classifications, five area types, and three counties ( Bexar, Comal, and Guadalupe). However, only one county ( Bexar) is located entirely within the TDM area ( i. e, Comal and Guadalupe counties do not play a role in the TDM VMT and speed estimation process).

HPMS VMT annual average daily traffic ( AADT, or average Monday through Sunday, January through December traffic) estimates are based on traffic count data collected according to a statistical sampling procedure specified by the Federal Highway Administration ( FHWA) designed to estimate VMT ( as well as lane miles and centerline miles). A wide range of traffic data is collected under the HPMS program. HPMS VMT, centerline miles, and lane miles are applied in this analysis. The HPMS VMT is categorized by seven functional classifications and three area types.

ATR vehicle counts are collected by TxDOT at selected locations on a continuous basis throughout Texas. These counts are available by season, month, and weekday, as well as on an AADT basis. Since they are continuous, they are especially well suited for making seasonal, day of week, and time of day comparisons ( i. e., adjustment factors), even though there may be relatively few ATR data collection locations in any given area. The ATR counts may also may be aggregated within time periods ( e. g., hours of day) and in the form of allocation factors, to distribute 24 hour VMT estimates, for example, to each hour of the day. 9 Vehicle classification counts are collected at representative locations throughout Texas on a regular but periodic basis. Roadway functional classification is included as part of the data collected. Vehicle classification counts were used to estimate the relative proportion of VMT to be assigned to each type of vehicle ( VMT mix is described later in this report).

HPMS VMT estimates are available for all counties. ATR and vehicle classification ( VMT mix) data are available for most but not all counties. Consequently, these last two data sources were aggregated for the SA/ MSA to provide adequate data for this analysis.

County Level VMT Totals This section discusses the seasonal adjustment factors, the HPMS adjustment for TDM future year VMT, development of the VMT totals for the TDM based county, and development of the VMT totals for the HPMSbased counties.

Seasonal Day of Week Factors Emissions estimates are required for the September Weekday, Friday, Saturday, and Sunday day types. Since the evaluation year base VMT estimates are either in AADT form ( HPMS based) or ANSWT form ( TDM based), September day type adjustment factors are needed to convert VMT from both of these forms of VMT. To develop the two September day type conversion factor sets for this analysis, three years ( 1999 through 2001) of SA/ MSA ATR data are aggregated.

The two sets of SA/ MSA level September day type factors include four ratios each, which are the September average Weekday, Friday, Saturday, and Sunday volumes to AADT volume, and the September average Weekday, Friday, Saturday, and Sunday volumes to ANSWT volume.

These MSA level factors are used for all evaluation years to convert either AADT VMT or ANSWT VMT to the selected seasonal day type form. The September Weekday, Friday, Saturday, and Sunday adjustment factors are shown in Table 5.

Table 5 SA/ MSA Level September Day Type VMT Factors*

Day Type For Conversion from ANSWT For Conversion from AADT Weekday** 0.98018 1.03667 Friday 1.12041 1.18499 Saturday 0.87052 0.92069 Sunday 0.68856 0.72824 * Factors are based on SA/ MSA county ATR data from 1999 through 2001. ** Average Monday through Thursday.

HPMS Adjustment for TDM Future Year VMT For air quality analyses, TDM network traffic assignment VMT are adjusted to consistency with HPMS VMT. For TDM model analysis years where historical official HPMS VMT estimates are available, county HPMS VMT control totals are disaggregated to the network links proportionally to the model VMT ( including the intrazonal estimate) on each link. A different adjustment must be made for the future years. 10 The HPMS adjustment for the future year network ( including intrazonal) VMT is performed using the TDM validation year ( i. e. 1995 for the San Antonio network) HPMS factor. This factor is the ratio of 1995 HPMS ANSWT VMT ( adjusted to ANSWT form with ATR based " AADT to ANSWT factor" of 1.05581) to 1995 TDM ANSWT VMT ( including the intrazonal estimate). Since Bexar County is the only county completely contained within the TDM area, the HPMS factor for Bexar County was developed and applied only to the future year link VMT for that county. The 1995 model validation year HPMS factor Bexar County is 1.01083779. The calculation of this factor and the actual values used in this calculation are shown below.

HPMS VMT ( AADT) × ANSWT Adjustment Factor = HPMS VMT ( ANSWT)

HPMS VMT ( ANSWT) / Model VMT ( ANSWT) = HPMS Factor Bexar County: 1,351,818 × 1.02135 = 1,380,679.3 ( HPMS ANSWT VMT) 1,380,679.3 / 1,849,830.0 = 0.74638173 ( HPMS Factor) 11 Estimation of TDM Based County VMT Totals To calculate the HPMS consistent TDM based county VMT totals for each evaluation year and day type, three main steps were applied. First, the seasonal day type specific 1999 and 2007 evaluation year VMT were estimated, as the TDM network assignments were available for these two evaluation years. Next, growth rates were estimated for use in factoring the 2015 network link VMT estimates to the 2012 intermediate year VMT values. Finally, the adjustment factor sets were applied to the appropriate networks to produce the September day type link VMT for each county for the remaining evaluation years ( hourly and directional factors are discussed later).

Since TDMs do not assign intrazonal VMT to the network links, intrazonal VMT is estimated and assigned a link ( i. e. A node = B node = zone centroid). Each of the 24 hour TDM network data sets ( 1999, 2007, and 2015) were processed to produce link estimates for total ANSWT VMT to include both the network and intrazonal VMT ( which is assumed to be a part of the " local" road type VMT estimate). The intrazonal VMT is estimated as the product of the number of intrazonal trips, the average intrazonal travel time, and the average of the zone's coded centroid connector link speeds.

For the 1999 evaluation year the official historical 1999 HPMS AADT VMT estimate is available. To estimate the 1999 link VMT, county level seasonal day type adjusted HPMS VMT control totals were used. These control totals were disaggregated to the 1999 TDM network assignment links proportionally to the unadjusted model ( and added intrazonal) VMT on each link. The Bexar county 1999 seasonal day type control totals are calculated by multiplying the Bexar county HPMS AADT VMT total by the seasonal day type factor ( for AADT, see Table 5 above). This calculation was performed for each of the four day types. Since Comal and Guadalupe counties are only partially within the TDM area, this process is not applied to the TDM link VMT for those counties and the assigned network VMT is assumed to be the control totals.

For the 2007 evaluation year, the link VMT estimates were calculated by multiplying the unadjusted TDM link ( and intrazonal) VMT by two factors: the 1997 TDM validation year county level HPMS factor ( described above), and the SA/ MSA level seasonal day type factor ( for ANSWT, Table 5 above). Since Comal and Guadalupe counties are only partially contained within the TDM network, the HPMS factor and seasonal day type factor are assumed as 1.0 ( i. e, the VMT for these counties are not considered in the TDM VMT estimation process).

To estimate the link VMT for the intermediate year ( 2012) a growth rate for Bexar County was developed. A growth rate was computed using the HPMS consistent link and intrazonal TDM VMT estimates from the 2007 and 2015 TDMs. The estimated annual growth rate for Bexar County is 1.01829773. This growth rate was then transformed to a factor used to convert the 2015 link VMT estimates to the 2012 link VMT estimates. This conversion factor is calculated as the annual growth rate to the power of the target year minus the base year ( i. e. conversion factor = [ 1.01829773] 2012 2015). The conversion factor for Bexar County is 0.94705603.

The 2012 link VMT estimates were calculated by multiplying the 2015 network and intrazonal unadjusted link VMT by the 1997 validation year HPMS factor, the 2015 to 2012 conversion factor, and the September day type factor. As with the previous TDM VMT adjustments, Comal and Guadalupe counties are exempt from these adjustments since they are not completely within the TDM area ( i. e, all VMT factors are assumed as 1.0). This procedure was performed for each of the four September day type factors to produce the 2012 September Weekday, Friday, Saturday, and Sunday link VMT estimates for each county.

The fully adjusted county level evaluation year September Weekday, Friday, Saturday, and Sunday VMT totals are summarized in Tables 1 through 4, respectively.

HPMS Counties The base link VMT for the HPMS based counties is AADT. The 1999 evaluation year base VMT estimate is the historical HPMS VMT total for each county. For the evaluation years with no historical HPMS AADT VMT estimates available, HPMS AADT forecasts were made.

TxDOT HPMS AADT VMT data for each county for 1990 through 2000, in combination with official ( i. e., U. S. Census and TSDC) county population statistics and projections, were used to develop VMT forecasts. More specifically, there are conceptually two types of VMT, local and through. Local VMT is generated by the residents 12 of the county. Through VMT is generated by persons and vehicles passing through the county. The relative importance varies by the proximity of the county to large urban areas ( that generate substantial VMT of their own).

Theoretically, local VMT is more closely related to population, while through VMT is more closely related to historical VMT. Though these distinctions are not absolute ( i. e., local VMT is not independent of historical patterns and through VMT is not independent of county population), they imply very different strategies for forecasting. Local VMT is likely to be a function of population, while through VMT is likely to be a function of historical VMT ( i. e., growth). If used alone, however, each tends to err in a different direction. Population based forecasts ( i. e., VMT per capita) tend to under estimate future VMT, especially in small counties adjacent to large urban areas. Conversely, historical based ( i. e., growth trend) forecasts tend to over estimate future VMT, especially in areas where there has been recent atypical rapid growth.

Viewed differently, however, these two forecast strategies define the boundaries of the forecast, that is, defining a range that will produce credible results. Consequently, the strategy adopted for the HPMS based counties ( Comal, Guadalupe, and Wilson) was to use the midpoint of the two forecasts. In other words, both methods were used. First, a forecast was developed for each county with a per capita based method using a VMT to population ratio ( based on 1990 through 2000 population and VMT) applied to future official TSDC population projections. Next, a traditional regression analysis was performed on the historic HPMS VMT data from 1990 to 2000 to develop coefficients that were then used to forecast future VMT for each near nonattainment county. Then, the two forecasts were combined and the midpoint calculated. The midpoint of the two methods was used as the forecast VMT value for each county for each forecast year.

Table 6 shows the county level AADT VMT estimates, 1999 official historical and future year forecasts.

Table 6 County Level HPMS Historical and Forecast AADT VMT Estimates Year Comal Guadalupe Wilson 1999 2,942,456 2,648,162 724,954 2007 3,660,790 3,234,444 908,357 2012 4,146,266 3,604,174 1,020,359 These AADT estimates were adjusted to each of the four September day type control total values ( as shown in Tables 1 through 4) using the seasonal day type factors for conversion of VMT from the AADT form ( Table 5). To allocate county control total VMT by the HPMS functional classifications, 1999 historical official HPMS functional class and area type ( virtual link) AADT VMT proportions were used. By county, for each evaluation year and day type, the VMT control totals were disaggregated to the HPMS virtual links proportionally to the 2000 HPMS AADT VMT on each link.

Hourly Travel and Directional Factors Emissions estimates are required by hour during September for each of the four day types. Since the VMT forecasts are 24 hour estimates, hourly travel factors are required to apportion the VMT to each hour of the day.

TxDOT continuous ATR data ( for 1999 and 2001) from the SA/ MSA counties were aggregated to develop MSA level hourly travel factors for application at the county level. Hourly travel factors were developed for each of the four day types. Using the September day type specific volumes, these factors are the ratio of hourly volumes to 24 hour volume. Table 7 shows the hourly travel factors for the SA/ MSA counties. 13 The MSA level hourly factors were applied to the 24 hour link VMT estimates for each county to produce the hourly link VMT estimates for each of the four day types. The same set of hourly factors were applied for all evaluation years. 14 Table 7 Hourly Travel Factors* for the SA/ MSA Hour Weekday** Friday Saturday Sunday 12: 00 a. m. 0.00922 0.00914 0.02178 0.02880 1: 00 a. m. 0.00569 0.00607 0.01444 0.01928 2: 00 a. m. 0.00522 0.00561 0.01331 0.01806 3: 00 a. m. 0.00429 0.00419 0.00810 0.01083 4: 00 a. m. 0.00637 0.00608 0.00732 0.00745 5: 00 a. m. 0.01657 0.01496 0.01125 0.00917 6: 00 a. m. 0.05101 0.04510 0.02109 0.01462 7: 00 a. m. 0.07734 0.07028 0.03184 0.01981 8: 00 a. m. 0.06463 0.05810 0.04166 0.02682 9: 00 a. m. 0.04881 0.04591 0.04898 0.04041 10: 00 a. m. 0.04764 0.04645 0.05564 0.05123 11: 00 a. m. 0.05209 0.05177 0.06210 0.05792 12: 00 p. m. 0.05429 0.05460 0.06636 0.06880 1: 00 p. m. 0.05584 0.05603 0.06656 0.07280 2: 00 p. m. 0.05933 0.05986 0.06688 0.07384 3: 00 p. m. 0.06724 0.06671 0.06575 0.07282 4: 00 p. m. 0.07663 0.07337 0.06388 0.07209 5: 00 p. m. 0.08131 0.07476 0.06210 0.07028 6: 00 p. m. 0.06384 0.06291 0.05990 0.06612 7: 00 p. m. 0.04558 0.05092 0.05383 0.05577 8: 00 p. m. 0.03732 0.04143 0.04672 0.04780 9: 00 p. m. 0.03172 0.03724 0.04284 0.04000 10: 00 p. m. 0.02285 0.03370 0.03812 0.03226 11: 00 p. m. 0.01517 0.02481 0.02955 0.02302 * Based on 1999 through 2001 SA/ MSA aggregate ATR count data. ** Average Monday through Thursday. 15 Finally, the VMT were apportioned by direction to allow for differences in congestion levels based on the direction of traffic flow. Directional volumes are required for modeling directional operational speeds, discussed in the next section. The directional split ratio applied for the HPMS based counties is 60/ 40 based on aggregate observed values for areas where data are available. The directional splits used for the TDM based counties vary by network functional classification and area type and by peak and off peak travel periods. The directional splits and their corresponding travel periods for the TDM based analysis are listed in Appendix C.

Tables 8 and 9, respectively, show the San Antonio TDM network functional classes and area types. Table 10 shows the HPMS functional classes and area types. 16 Table 8 San Antonio TDM Network Functional Classifications Functional Class Code Functional Class Name 0 Local Roads 1 Radial Freeway 2 Radial Parkway 3 Expressway 4 Primary Arterial Divided 5 Primary Arterial Undivided 6 Minor Arterial Divided 7 Minor Arterial Undivided 8 Collectors Divided 9 Collectors Undivided 10 Frontage Road 11 Ramp 12 Circumferential Freeway 13 Circumferential Parkway 14 Circumferential Arterial 35 HOV*

40 Intrazonal * Only used 2015 network but classified as Radial Freeway due to lack of data for HOV. 17 Table 9 San Antonio TDM Network Area Types Area Type Code Area Type Name 1 Central Business District ( CBD)

2 Urban 3 Urban Residential 4 Suburban 5 Rural 6 Military Table 10 HPMS Functional Classes and Area Types HPMS Area Type* HPMS Roadway Functional Classification Rural Small Urban Urban Interstate Freeway Other Principal Arterial Minor Arterial Major Collector Minor Collector Local * For this analysis, the Urban area type is for population of 50,000 +.

Hourly and 24 hour VMT summaries ( by day type, road type, and vehicle type) are included with the EI data provided on CD ROM. Appendix A lists the electronic data files with descriptions.

ESTIMATION OF SPEEDS Speed is a critical parameter for estimating emissions. Similarly, capacity and freeflow speed ( and traffic volume, as discussed in the previous section) are critical parameters for determining speed. Capacity is the maximum flow past a given point on a roadway. It varies by the type of roadway ( i. e., by functional classification). Freeflow speed is the maximum speed that traffic will move along a given roadway if there are no impediments ( e. g., congestion, bad weather). To estimate a link's ( or " virtual" link, in the case of HPMS based analyses) directional, time of day congested speed, a speed model involving both the estimated freeflow speed and estimated directional delay as a function of volume and capacity for the link and time period is applied. The model is applied to each link ( except for TDM centroid connectors and the special intrazonal links) for each time period and direction. Development of the link capacities and freeflow speeds input to the speed model is first discussed, followed by the model delay and congested speed equations. 18 Capacities and Freeflow Speeds for HPMS based Analysis The capacities and freeflow speeds used for the HPMS based county analyses all come from the Highway Capacity Manual ( HCM). For HPMS functional classifications 1 and 2 ( interstate and freeway), both capacities and freeflow speeds are taken directly from the HCM ( 3 3). The capacity ( 2,200 passenger cars per hour per lane [ pcphpl]) and freeflow speed ( 70 mph) for four lane freeways was used for all interstates, regardless of area type. Similarly, a freeflow speed of 65 mph and capacity of 2,100 pcphpl was used for all freeways ( HCM figure 3 2a).

HPMS functional classifications 3, 4, 5, 6, and 7 ( principal arterial, minor arterial, major collector, minor collector, and local) have traffic control devices ( i. e., signals or stop signs) that determine their capacities. The capacities of these signalized roadways were calculated based on signalized intersection capacity defined as shown ( HCM 1994: 9 5, equation 9 3):

Ci= Si × ( gi/ C)

Where:

Ci = capacity of lane group i, vehicles per hour ( vph); Si = saturation flow rate of lane group i, vehicles per hour of effective green time ( vphg); and gi/ c = effective green ratio for lane group i.

The saturation flow rate ( Si) is the flow in vph that could be accommodated by the lane group assuming that the green phase was always available to the lane group ( i. e., green ratio = 1.0). Computation of the adjusted saturation flow rate begins with the ideal saturation flow rate of 1,900, which is adjusted to reflect variance from ideal conditions. The saturation flow rate was adjusted for area type using the following assumptions ( HCM 1994: 9 14, equation 9 12):

S = N × fw × fhv × fg × fp × fbb × fa × frt × flt Where:

S = saturation flow rate factor ( rounded to two decimal places); N = number of lanes in the lane group; fw = lane width adjustment factor ( 12 foot lane for all area types assumed); fhv = heavy vehicle adjustment factor ( five percent heavy vehicles for all area types to adjust for passenger car equivalents, not to be confused with VMT mix); fg = approach grade factor ( level terrain assumed for all area types); fp = parking lane adjustment ( none for rural areas, one maneuver per hour for urban areas); fbb = bus blocking factor ( none for rural areas, 10 per hour for urban areas, mid point for small urban areas); fa = area type adjustment ( 0.9 for urban area, 1.0 for all other areas); frt = right turn adjustment factor ( shared lane for right turns for all area types, high pedestrian crossing for urban areas, moderate for small urban areas, and low for rural); and flt = left turn adjustment factor ( exclusive left turn lanes and protected phasing for rural areas, shared left turn lanes and protected plus permitted phasing for urban areas, mid point for small urban areas).

Table 11 shows the saturation flow rate adjustment factors used for the three different area types.

Table 11 Saturation Flow Rate Adjust Factors by Area Type Area Type fw fhv fg fp fbb fa frt flt 19 Rural 1 0.95 1 1 1 1 0.98 0.95 Small Urban 1 0.95 1 0.98 0.98 1 0.94 0.90 Urban 1 0.95 1 0.95 0.96 0.90 0.90 0.85 Table 12 shows the effective green ratios used for different functional classes. The same ratios were used for all area types. ( Interstates and freeways are unsignalized and do not require green ratios.)

Table 12 Effective Green Ratios ( gi/ C) by HPMS Roadway Functional Classification Principal Arterial Minor Arterial Major Collector Minor Collector Local 0.60 0.55 0.50 0.40 0.30 Table 13 shows the adjusted saturation flow rate ( expressed in pcphpl) for all signalized streets ( i. e., not interstate or freeway) for the three area types.

Table 13 Adjusted Saturation Flow Rate ( pcphpl) by Area Type HPMS Area Type Ideal Flow Adjustment Factor Adjusted Saturation Flow Rural 0.88 1,672 Small Urban 0.77 1,463 Urban 1,900 0.59 1,121 The freeflow speed for rural and urban arterials ( FC 3 and FC 4) were taken directly from HCM ( HMC 1994: 7 10 and 11 6, respectively). The freeflow speed for other functional classes decreases from arterial freeflow speed by 5 mph increments. No freeflow speed is below 30 mph. Table 14 shows the hourly lane capacities for all functional classes and area types.

Table 14 Hourly Lane Capacities ( vehicles per hour per lane [ vphpl])

HPMS Roadway Functional Classification HPMS Area Type Interstate Freeway Other Principal Arterial Minor Arterial Major Collector Minor Collector Local Rural 2,200 2,100 1,003 920 836 669 502 20 Small Urban 2,200 2,100 878 805 732 585 439 Urban 2,200 2,100 673 617 561 448 336 Similarly, freeflow speeds are provided for each of the three area types and seven roadway functional classifications ( or 21 HPMS virtual links). Table 15 shows the freeflow speeds. 21 Table 15 Freeflow Speeds ( mph)

HPMS Roadway Functional Classification HPMS Area Type Interstate Freeway Other Principal Arterial Minor Arterial Major Collector Minor Collector Local Rural 70 65 55 50 40 35 30 Small Urban 70 65 45 40 35 30 30 Urban 70 65 40 35 30 30 30 V/ C ratios were generated for each combination of time period, roadway functional classification, area type, and direction using these capacities and VMT. The following describes the calculation for this procedure:

· Volume: VMT was multiplied by each 24 hourly time period factors yielding VMT for each time period. VMT per time period was divided by centerline miles, yielding volume for each time period. This procedure was performed for each combination of time period, roadway functional classification, area type, and direction.

· Capacity: Lane miles were divided by centerline miles to produce lanes. Lanes were multiplied by the lane capacities ( i. e., adjusted saturation flows) generated by the process described above, producing hourly lane capacities. Hourly lane capacities were multiplied by the number of hours in the time period to produce time period capacities. This procedure was performed for each combination of time period, roadway functional classification, and area type. ( Capacity is the same for each direction.)

· V/ C ratios: The speed model was applied to the resulting volumes and capacities for each functional classification and area type combination. This yields volumes adjusted for the impact of congestion related delay for each combination of time period, functional classification, area type, and direction.

Capacities and Freeflow Speeds for the TDM based Analysis The San Antonio TDM network 24 hour equilibrium assignments were performed using nondirectional 24 hour capacities. Time of day ( i. e., hourly) capacity factors were applied to nondirectional capacity ( or service volume) for the 24 hour assignment time period. In computing the directional v/ c ratio for estimating the directional speeds, the directional split for capacity is assumed at 50 50. The network was processed to compute the average capacity per lane by functional classification and area type. Appendix D summarizes the capacity factors, which are computed as follows:

Lane per Capacity hour  24 Period) Time the of th Lane)( Leng per Capacity ( Hourly = Factor Capacity 22 Freeflow speed factors are used to convert TDM level of service ( LOS) C speeds to LOS A ( i. e., freeflow) speeds. The freeflow speed factors for the San Antonio TDMs by area type and functional classification are shown in Appendix D.

With the freeflow speeds and hourly, directional volumes and capacities on each link, the congested speeds may be computed.

Estimation of Congested Speeds The congested speed model first calculates delay on the link which it then applies to the link freeflow speed to compute the link operational congested speed estimate. The volume/ delay equation is: Where:

Delay = congestion delay ( in minutes/ mile); A & B = volume/ delay equation coefficients; M = maximum minutes of delay per mile; and V/ C = time of day directional V/ C ratio.

The delay model parameters ( A, B, and M) were developed for the Dallas/ Fort Worth area and verified by application in other Texas urban areas. There is a set of parameters for high capacity facilities and a set for lowcapacity facilities ( see Table 16). The San Antonio network high capacity facility types are Radial Freeway, Radial Parkway, Circular Freeway and Circular Parkway. The remaining facility types ( except for centroid connector and intrazonal, which do not use capacity data) are low capacity facilities. The HPMS high capacity facilities are Interstate and Freeway classifications. M] , e [ A = Delay ) C V ( B Min 23 Table 16 Volume/ Delay Equation Parameters Facility Category A B M*

High Capacity Facilities (> 3,400 vph one way, e. g., Interstates and Freeways) 0.015 3.5 5.0 Low Capacity Facilities (< 3,400 vph, e. g., Arterials, Collectors and Locals) 0.050 3.0 10.0 * For HPMS, M values are 3.0 for high capacity and 5.0 for low capacity facilities.

Given the estimated directional delay ( in minutes/ mile) and the estimated freeflow speed, the directional congested speed is computed as follows:

Delay + speed Freeflow 60 60 = speed Congested This model is applied to each link, based on functional class and area type, for each time period and each direction.

TDM Centroid Connector and Intrazonal Speeds For the centroid connector links and intrazonal links ( intrazonal links are developed specifically for air emissions analyses), capacity data are not used. The centroid connector traffic assignment input speeds were used as the centroid connector operational speeds estimates. Operational speeds for the intrazonal trips category were estimated by zone as the average of the zone's centroid connector speeds.

The hourly and 24 hour VMT weighted speed summaries by county and road type are included in the set of data files provided to TCEQ on CD ROM ( see Appendix A for electronic data descriptions). Tables 1 through 4 summarize the San Antonio MSA county 24 hour average speeds calculated as total VMT divided by total VHT.

VMT MIX VMT mix for 1999, 2007, and 2012 were estimated using TxDOT 1997  1999 vehicle classification data for 1999 and TxDOT 1997  2001 vehicle classification data for subsequent years. As was the case with the seasonal adjustment factor for the VMT estimation procedure, the four county San Antonio area data were aggregated.

TxDOT classification counts classify vehicles into the standard FHWA vehicle classifications ( based on vehicle length/ number of axles) using best practice vehicle classification count methods.

C Passenger vehicles; P Two axle, four tire single unit trucks; B Buses; SU2 Six tire, two axle single unit vehicles; SU3 Three axle single unit vehicles; SU4 Four or more axle single unit vehicles; SE4 Three or four axle single trailer vehicles; SE5 Five axle single trailer vehicles; SE6 Six or more axle single trailer vehicles; SD5 Five or less axle multi trailer vehicles; 24 SD6 Six axle multi trailer vehicles; and SD7 Seven or more axle multi trailer vehicles.

EPA and MOBILE use a different vehicle classification scheme than the FHWA categories. The 28 EPA vehicle categories are defined as a function of gross vehicle weight rating ( GVWR) and fuel type ( see Table 17). The FHWA axle/ vehicle length based classification categories must be converted into 28 MOBILE GVWR/ fuel type based categories. 25 Table 17 EPA Vehicle Types  28 Categories Category Description GVWR LDGV Light duty gasoline vehicle < 6,000 LDGT1 Light duty gasoline truck < 6,000 LDGT2 Light duty gasoline truck < 6,000 LDGT3 Light duty gasoline truck 6,001  8,500 LDGT4 Light duty gasoline truck 6,001  8,500 HDGV2b Heavy duty gasoline vehicle 8,501  10,000 HDGV3 Heavy duty gasoline vehicle 10,001  14,000 HDGV4 Heavy duty gasoline vehicle 14,001  16,000 HDGV5 Heavy duty gasoline vehicle 16,001  19,500 HDGV6 Heavy duty gasoline vehicle 19,501  26,000 HDGV7 Heavy duty gasoline vehicle 26,001  33,000 HDGV8a Heavy duty gasoline vehicle 33,001  60,000 HDGV8b Heavy duty gasoline vehicle > 60,000 HDGB Heavy duty gasoline bus all LDDV Light duty diesel vehicle < 6,000 LDDT12 Light duty diesel truck < 6,000 LDDT34 Light duty diesel truck 6,001  8,500 HDDV2b Heavy duty diesel vehicle 8,501  10,000 HDDV3 Heavy duty diesel vehicle 10,001  14,000 HDDV4 Heavy duty diesel vehicle 14,001  16,000 HDDV5 Heavy duty diesel vehicle 16,001  19,500 HDDV6 Heavy duty diesel vehicle 19,501  26,000 HDDV7 Heavy duty diesel vehicle 26,001  33,000 HDDV8a Heavy duty diesel vehicle 33,001  60,000 HDDV8b Heavy duty diesel vehicle > 60,000 HDDBS Heavy duty diesel school bus all HDDBT Heavy duty diesel transit bus all MC Motorcycle all 26 The FHWA category counts ( based on number of axles or vehicle length) are first converted into categories ( based on GVWR). Vehicle classification counts are first aggregated into three intermediate groups.

Passenger Vehicles ( PV) C + P; Heavy Duty Vehicles ( HDV) SU2 + SU3 + SU4 + SE4; and HDDV8b ( HDX) SE5 + SE6 + SD5 + SD6 + SD7.

This is followed by a second intermediate allocation that separates light duty vehicles ( LDV) into passenger cars and light duty trucks ( LDT) based on TxDOT registration data.

LDV 0.708 × PV ( by county, 2002 Bexar registration data shown); and LDT 0.292 × PV ( by county, 2002 Bexar registration data shown).

A third intermediate allocation further separates LDTs into LDT1 and HLDT. ( Note that LDT1 is itself intermediate and is further divided into LDGT1 and LDDT.)

LDT1 0.842 × LDT ( by county, 2002 Bexar registration data shown); and HLDT 0.158 × LDT ( by county, 2002 Bexar registration data shown).

Next, the remaining FHWA categories are disaggregated into EPA vehicle groups, as shown. Note that TxDOT vehicle classification count procedures do not distinguish between gasoline and diesel LDTs. Consequently, MOBILE defaults for the year of interest are used. As before, actual TxDOT vehicle registration data are used to separate gasoline from diesel heavy duty trucks. Note also that motorcycles are not counted separately and are included as a default ( subtracted from LDGV).

LDGV 0.9972136 × LDV ( MOBILE6 default for 1999 shown); LDDV 0.0027864 × LDV ( MOBILE6 default for 1999 shown); LLDT 0.9936534 × LDT1 ( MOBILE6 default for 1999 shown); LDDT 0.0063466 × LDT1 ( MOBILE6 default for 1999 shown); HDGV 0.333 × HDV ( by county, 2002 Bexar registration data shown); HDDV 0.667 × HDV ( by county, 2002 Bexar registration data shown); and MC 0.001 of total ( subtracted from LDGV).

This converts the FHWA axle count based categories into GVWR categories. This part of the conversion procedure is summarized schematically in Table 18. Starting with the TxDOT vehicle classification data, these data themselves provide sufficient information to complete the first step in the conversion process, the allocation of vehicles into passenger vehicles ( PV), heavy duty vehicles ( HDV), five axle heavy duty vehicles ( HDDV8b), and buses ( B). Steps 2 and 3 further allocate these categories using TxDOT registration data. Finally, Step 4 allocates light duty vehicles by fuel type using EPA MOBILE diesel fractions and motorcycles are separated from light duty gas vehicles using a nominal constant.

Table 18 Initial Vehicle Classification Conversion Procedure Start Step 1 Step 2 Step 3 Step 4 MC LDGV LDGV LDV LDDV Total Vehicles PV LDT LDT1 LLDT 27 LDDT HLDT HDGV HDV HDDV HDDV8b B The MOBILE6 28 category typology is a subset of this typology. A combination of EPA MOBILE6 defaults and Texas vehicle registration data are used to expand these intermediate categories.

For the 28 category EPA scheme, heavy duty vehicles ( HDV) are separated into eight and seven categories respectively. HDDV8b vehicle are counted directly. The 15 HDV categories are separated from total HDV, which have been separated by fuel type ( HDGV and HDDV) using TxDOT registration data. Each HDV category ( HDGV and HDDV) is then divided into sub categories based on detailed area wide TxDOT county vehicle registration data. Buses are treated separately.

The 28 category EPA scheme also further divides the two LDT categories based in part on assumed loading. The previous LDGT1 and LDGT2 categories ( previously defined as GVWR < 6,000 and GVWR > 6,000 to 8,500, respectively) are separated into subcategories in terms of adjusted loaded vehicle weight ( ALVW). ALVW is the average of vehicle curb weight and GVWR. Thus, two new intermediate categories are introduced. These are light light duty trucks ( LLDT) and heavy light duty trucks ( HLDT), which are defined as:

· LLDT  any light duty truck rated through 6,000 pounds GVWR, and · HLDT  any light duty truck rated greater than 6,000 pounds GVWR.

These two new intermediate categories are then used to define the four LDT categories using EPA MOBILE6 defaults for the year of interest. The four LDT categories are:

· LDGT1  light light duty trucks through 3,750 pounds loaded vehicle weight ( LVW); · LDGT2  light light duty trucks greater than 3,750 pounds LVW; · LDGT3  heavy light duty trucks to 5,750 pounds ALVW; and · LDGT4  heavy light duty trucks greater than 5,750 pounds ALVW.

Similarly, the LDDT category is sub divided into two categories based on GVWR ( less than or equal to 6,000 GVWR and 6,000 to 8,500 GVWR). This is accomplished using EPA MOBILE6 default values for the year of interest.

Finally the three bus categories are separated from the TxDOT classification counts bus category using EPA MOBILE6 default values. ( Under MOBILE6 the HDV category does not include buses.)

Vehicle classification data is not forecast. For future VMT mix estimates, MOBILE6 default values consistent with the future year are used ( i. e., 2007). For historical VMT mix estimates, the MOBILE6 default values consistent 28 with the historical year are used ( i. e., 1997  1999 for a 1999 analysis year). No other adjustments are made to alter the count data and conversion procedure to accommodate future years or historical years. Table 19 shows the VMT mix estimation procedure summary followed by explanatory notes. For this analysis, VMT mix estimates were developed for three functional classification groups ( identified later in the " Emissions Estimation" section of this report).

This procedure is performed as described for weekdays. TxDOT vehicle classification data are only collected for weekdays ( Monday through Thursday), consequently other data is used to estimate VMT mix for Fridays, Saturdays, and Sundays. The procedure used to estimate Friday, Saturday, and Sunday VMT mix relies on vehicle classification data collected over several years in urban areas. The ratio of weekday VMT mix to Friday, Saturday, and Sunday VMT mix is applied to the weekday VMT mix to produce region specific Friday, Saturday and Sunday VMT mix. ( No seasonal changes are assumed.) 29 Table 19 VMT Mix Estimation Procedure Summary EPA 8 EPA 28 Conversion LDGV LDGV .9972 × LDV LDGT1 .2310 × LLDT LDGT1 LDGT2 .7690 × LLDT LDGT3 .6850 × HDLT LDGT2 LDGT4 .3150 × HDLT HDGV2b .430 × HDGV HDGV3 .203 × HDGV HDGV4 .081 × HDGV HDGV5 .048 × HDGV HDGV6 .153 × HDGV HDGV7 .049 × HDGV HDGV8a .029 × HDGV HDGV8b .007 × HDGV HDGV HDGB .2045 × B LDDV LDDV .0028 × LDV LDDT12 .1623 × LDDT LDDT LDDT34 .8377 × LDDT HDDV2b .273 × HDDV HDDV3 .122 × HDDV HDDV4 .063 × HDDV HDDV5 .046 × HDDV HDDV6 .199 × HDDV HDDV7 .119 × HDDV HDDV8a .178 × HDDV HDDV8b HDX HDDBT .3253 × B HDDV HDDBS .4702 × B MC MC MC 30 Notes to VMT Mix Estimation Procedure Summary Intermediate category factors and sources:

LDV .708 × PV ( by county, 2002 Bexar registration data shown) LDT .292 × PV ( by county, 2002 Bexar registration data shown) LDT1 .842 × LDT ( by county, 2002 Bexar registration data shown) HLDT .158 × LDT ( by county, 2002 Bexar registration data shown) LLDT .9937 × LDT1 ( EPA MOBILE6 default) LDDT .0063 × LDT1 ( EPA MOBILE6 default) HDV SU2+ SU3+ SU4+ SE3+ SE4 HDX SE5+ SE6+ SD5+ SD6+ SD7 HDGV .333 × HDV ( by county, 2002 Bexar registration data shown) HDDV .667 × HDV ( by county, 2002 Bexar registration data shown)

Category conversion factors and sources:

LDGV .9972 × LDV ( EPA MOBILE6 default, 1999 shown) LDGT1 .2310 × LLDT ( EPA MOBILE6 default, 1999 shown) LDGT2 .7690 × LLDT ( EPA MOBILE6 default, 1999 shown) LDGT3 .6850 × HLDT ( EPA MOBILE6 default, 1999 shown) LDGT4 .3150 × HLDT ( EPA MOBILE6 default, 1999 shown) HDGV2a .430 × HDGV ( San Antonio area registration data) HDGV3 .203 × HDGV ( San Antonio area registration data) HDGV4 .081 × HDGV ( San Antonio area registration data) HDGV5 .048 × HDGV ( San Antonio area registration data) HDGV6 .153 × HDGV ( San Antonio area registration data) HDGV7 .049 × HDGV ( San Antonio area registration data) HDGV8a .029 × HDGV ( San Antonio area registration data) HDGV8b .007 × HDGV ( San Antonio area registration data) HDGB .2243 × B ( EPA MOBILE6 default, 1999 shown) LDDV .0028 × LDV ( EPA MOBILE6 default, 1999 shown) LDDT12 .2723 × LDDT ( EPA MOBILE6 default, 1999 shown) LDDT34 .7277 × LDDT ( EPA MOBILE6 default, 1999 shown) HDDV2b .273 × HDDV ( San Antonio area registration data) HDDV3 .122 × HDDV ( San Antonio area registration data) HDDV4 .063 × HDDV ( San Antonio area registration data) HDDV5 .046 × HDDV ( San Antonio area registration data) HDDV6 .199 × HDDV ( San Antonio area registration data) HDDV7 .119 × HDDV ( San Antonio area registration data) HDDV8a .178 × HDDV ( San Antonio area registration data) HDDV8b HDX ( TxDOT classification counts) HDDBT .3240 × B ( EPA MOBILE6 default, 1999 shown) HDDBS .4517 × B ( EPA MOBILE6 default, 1999 shown) MC MC ( default subtracted from LDGV, no conversion) ESTIMATING EMISSIONS FACTORS The MOBILE6 model ( October 2002) was applied to calculate day of week specific 1999, 2007 and 2012 emissions factors ( in grams per mile [ g/ mi]) of VOC, CO, and NOx. Emissions factors are estimated by speed, emissions type ( i. e., emissions factor sub component), hour, MOBILE6 road type ( or drive cycle), and vehicle type for the fourcounty MSA. The average emissions factors for each of the 28 vehicle types are developed by combining the MOBILE6 database output by model year emissions factors weighted by their corresponding travel fractions. The emissions factors are organized in the form of " look up" tables. 31 The MOBILE6 model is equipped with national ( or EPA) default modeling values for a wide range of conditions that affect emissions factors. In fact, the only actual data parameters requiring user input values to run the model are fuel Reid Vapor Pressure ( RVP), temperature, and calendar year. Many MOBILE6 default modeling parameters may be overridden through the use of MOBILE6 commands and their associated inputs and options. For this analysis, particular MOBILE6 defaults were replaced by local input values that were developed to yield emissions factors characteristic of the September 1999 ozone episode climatic conditions, evaluation specific vehicle fleets, activity, and emissions control programs.

The following emissions factors documentation discusses the MOBILE6 input/ output files, summarizes the control programs modeled, details the aggregation level of the applied MOBILE6 emissions factors, and briefly describes all of the MOBILE6 commands that may affect emissions factor calculations. It also identifies the commands that were applied, explains the development of the locality specific inputs, and describes the emissions factor post processing procedure.

MOBILE6 Input and Output Files The MOBILE6 commands and some model input data are entered in the MOBILE6 command file. Other input parameters ( and in some cases, commands) are applied to MOBILE6 from external data files.

The POLFAC62 program ( see program descriptions in Appendix B) was applied to run MOBILE6 with the user input command and external data files to produce VOC, CO, and NOx emissions factor tables. ( The RATEADJV6 program was applied to POLFAC62 output where post processing of emissions factors was required, discussed later.) The final product of the emissions factor modeling is four hourly MSA level emissions factor files ( one per episode day) for each of the three evaluation years.

All of the MOBILE6 input files and output files ( MOBILE6 emissions factor tables developed with POLFAC62, and RATEADJV62) are included in the set of data files provided on CD ROM. Appendix A describes the electronic data submittal. 32 Control Programs Modeled ( And Emissions Factor Post Processing Summary) All federal motor vehicle control programs, particular to evaluation year, were modeled ( this is the MOBILE6 default). Also modeled were the federal programs to offset HDDV defeat device effects   the low emissions rebuild program, and the HDDV 2004 standard pull ahead program ( this is the MOBILE6 default). The Texas Regional Low Reid Vapor Pressure Gasoline Program and Texas LED Program were modeled as well. Emissions reduction estimates for the vehicle Anti tampering Program ( ATP), although administered statewide, are credited only to those counties with enforced Inspection and Maintenance ( I/ M) Programs, which excludes the San Antonio area counties.

Post processing of MOBILE6 emissions factors was performed for modeling LED ( required for 2007 and 2012) for the MSA. The procedures used to overcome the limits of MOBILE6 as related to the diesel fuel modeling requirements for this analysis are discussed in detail later in this section.

Aggregation Level of MOBILE6 Emissions Factors The by model year emissions factors from the MOBILE6 database output format are condensed into average fleet emissions factors by vehicle class. This is performed by weighting ( multiplying) each by model year emissions factor by its corresponding travel fraction and summing the resulting products. Each emissions factor table provides the MOBILE6 emissions factors by:

· 28 vehicle types, · 4 road types, · 14 speeds ( except for two MOBILE6 road types, each with one average speed), · 15 pollutant specific emissions types, and · 24 hourly time periods.

Tables 20 through 22 describe the MOBILE6 vehicle type, emissions type ( pertaining to VOC, CO, and NOx pollutants only), and roadway type classifications. Tables 23 and 24 show the speeds and sequence for hourly time periods, respectively.

Table 20 shows the 28 MOBILE6 vehicle types as defined by fuel type ( gasoline or diesel) and GVWR category, in sequence by EPA vehicle type number. 33 Table 20 Complete MOBILE6 Vehicle Classifications Number Abbreviation Description 1 LDGV Light Duty Gasoline Vehicles ( Passenger Cars)

2 LDGT1 Light Duty Gasoline Trucks 1 ( 0 6,000 lbs. GVWR, 0 3,750 lbs. LVW)

3 LDGT2 Light Duty Gasoline Trucks 2 ( 0 6,000 lbs. GVWR, 3,751 5,750 lbs. LVW)

4 LDGT3 Light Duty Gasoline Trucks 3 ( 6,001 8,500 lbs. GVWR, 0 5,750 lbs. ALVW*)

5 LDGT4 Light Duty Gasoline Trucks 4 ( 6,001 8,500 lbs. GVWR, 5,751 lbs. and greater ALVW) 6 HDGV2b Class 2b Heavy Duty Gasoline Vehicles ( 8,501 10,000 lbs. GVWR)

7 HDGV3 Class 3 Heavy Duty Gasoline Vehicles ( 10,001 14,000 lbs. GVWR)

8 HDGV4 Class 4 Heavy Duty Gasoline Vehicles ( 14,001 16,000 lbs. GVWR)

9 HDGV5 Class 5 Heavy Duty Gasoline Vehicles ( 16,001 19,500 lbs. GVWR)

10 HDGV6 Class 6 Heavy Duty Gasoline Vehicles ( 19,501 26,000 lbs. GVWR)

11 HDGV7 Class 7 Heavy Duty Gasoline Vehicles ( 26,001 33,000 lbs. GVWR)

12 HDGV8a Class 8a Heavy Duty Gasoline Vehicles ( 33,001 60,000 lbs. GVWR)

13 HDGV8b Class 8b Heavy Duty Gasoline Vehicles (> 60,000 lbs. GVWR)

14 LDDV Light Duty Diesel Vehicles ( Passenger Cars)

15 LDDT12 Light Duty Diesel Trucks 1 and 2 ( 0 6,000 lbs. GVWR)

16 HDDV2b Class 2b Heavy Duty Diesel Vehicles ( 8,501 10,000 lbs. GVWR)

17 HDDV3 Class 3 Heavy Duty Diesel Vehicles ( 10,001 14,000 lbs. GVWR)

18 HDDV4 Class 4 Heavy Duty Diesel Vehicles ( 14,001 16,000 lbs. GVWR)

19 HDDV5 Class 5 Heavy Duty Diesel Vehicles ( 16,001 19,500 lbs. GVWR)

20 HDDV6 Class 6 Heavy Duty Diesel Vehicles ( 19,501 26,000 lbs. GVWR)

21 HDDV7 Class 7 Heavy Duty Diesel Vehicles ( 26,001 33,000 lbs. GVWR)

22 HDDV8a Class 8a Heavy Duty Diesel Vehicles ( 33,001 60,000 lbs. GVWR)

23 HDDV8b Class 8b Heavy Duty Diesel Vehicles (> 60,000 lbs. GVWR)

24 MC Motorcycles ( Gasoline)

25 HDGB Gasoline Buses ( School, Transit, and Urban)

26 HDDBT Diesel Transit and Urban Buses 27 HDDBS Diesel School Buses 28 LDDT34 Light Duty Diesel Trucks 3 and 4 ( 6,001 8,500 lbs. GVWR)

* The adjusted loaded vehicle weight is the numerical average of the vehicle curb weight and the GVWR. Source: MOBILE6 User's Guide ( EPA, January 2002). 34 Table 21 shows the eight MOBILE6 emissions type classifications ( excluding the non pertinent pollutants). Expanding these emissions types by individual pollutant yields 12 pollutant specific emissions types. In addition to these 12 pollutant specific emissions types, POLFAC62 emissions factor tables contain the three composite emissions factors ( i. e., one for each pollutant). Thus, POLFAC62 calculates MOBILE6 emissions factors for up to 15 pollutant specific emissions types. For this analysis, MOBILE6 emissions factors were calculated for all of the 15 pollutant specific emissions types except for refueling emissions, which are classified as an area source emissions category.

Table 21 MOBILE6 Emission Type Classifications Number Abbreviatio n Description Pollutants Vehicle Classes 1 Running Exhaust Running Emissions Hydrocarbon ( HC), CO, NOx All 2 Start Exhaust Engine Start Emissions ( trip start) HC, CO, NOx LD plus MC 3 Hot Soak Evaporative Hot Soak Emissions ( trip end) HC Gas, including MC 4 Diurnal Evaporative Diurnal Emissions ( heat rise) HC Gas, including MC 5 Resting Evaporative Resting Loss Emissions ( leaks and seepage) HC Gas, including MC 6 Run Loss Evaporative Running Loss Emissions HC Gas, less MC 7 Crankcase Evaporative Crankcase Emissions ( blow by) HC Gas, including MC 8 Refueling Evaporative Refueling Emissions ( fuel displacement and spillage) HC Gas, less MC Source: MOBILE6 User's Guide ( EPA, January 2002).

MOBILE6 calculates emissions factors reflective of driving cycles observed on four roadway types, as well as emissions factors for those emissions types that are not directly applicable to the driving cycles. Table 22 provides descriptions of the driving cycle ( or roadway type). The fifth roadway type, according to MOBILE6 is " None." None, or roadway type number 5, is the index for the emissions types that do not apply to the driving cycles, and thus are not sensitive to, or do not vary by, roadway type or speed.

The POLFAC62 emissions factor table, however, categorizes all of the pollutant specific emissions types by MOBILE6 roadway types one through four   Freeway, Arterial, Local, and Ramp. That is, in POLFAC62 tables, the MOBILE6 g/ mi emissions factors corresponding to the " None" roadway type are tabulated as emissions factors under each of the four actual roadway types. This allocation of the MOBILE6 " None" road type emissions factors to the Freeway, Arterial, Local, and Ramp MOBILE6 road types is performed in POLFAC62 to facilitate the geographical allocation of the link emissions estimates by the roadway link coordinates.

Table 22 MOBILE6 Roadway Classifications 35 Number Abbreviation Description 1 Freeway High Speed, Limited Access Roadways 2 Arterial Arterial and Collector Roadways 3 Local Urban Local Roadways 4 Fwy Ramp Freeway on and off ramps 5 None Not Applicable ( for start and some evaporative emissions)

Source: MOBILE6 User's Guide ( EPA, January 2002).

Table 23 shows the 14 speeds used for calculating and tabulating the MOBILE6 Freeway and Arterial emissions factors. Later in the emissions estimation process, emissions factors for average operational speeds that are not represented in the 14 speeds as tabulated, are calculated by interpolation ( except for those speeds higher than the MOBILE6 maximum speed, and those lower than the MOBILE6 minimum speed, in which case the emissions factors corresponding to these bounding speeds are used, respectively). The MOBILE6 Local and Ramp road type emissions factors are not speed sensitive and are each characterized by one average speed. 36 Table 23 Speeds for POLFAC62 Tabulated MOBILE6 Freeway and Arterial Emissions Factors*

Number Speed 1 2.5 mph 2 5 mph 3 10 mph 4 15 mph 5 20 mph 6 25 mph 7 30 mph 8 35 mph 9 40 mph 10 45 mph 11 50 mph 12 55 mph 13 60 mph 14 65 mph * The MOBILE6 Local and Ramp drive cycle emissions factor's fixed speeds are 12.9 and 34.6 mph, respectively.

MOBILE6 uses several hourly input parameters ( e. g., hourly temperatures, hourly VMT fractions, etc.) to model hourly emissions factors. MOBILE6 requires that hourly input parameters be sequenced starting from the 6 a. m. hour. In some cases, however, particular overnight hours are grouped together as a single time period. Table 24 shows the MOBILE6 sequence for hourly inputs. 37 Table 24 General Sequence for Calendar Day Hourly* Inputs to MOBILE6 Input Sequence Number Abbreviation Description 1 6 a. m. 6 a. m. through 6: 59 a. m.

2 7 a. m. 7 a. m. through 7: 59 a. m.

3 8 a. m 8 a. m. through 8: 59 a. m.

4 9 a. m. 9 a. m. through 9: 59 a. m.

5 10 a. m. 10 a. m. through 10: 59 a. m.

6 11 a. m. 11 a. m. through 11: 59 a. m.

7 12 Noon 12 p. m. through 12: 59 p. m.

8 1 p. m. 1 p. m. through 1: 59 p. m.

9 2 p. m. 2 p. m. through 2: 59 p. m.

10 3 p. m. 3 p. m. through 3: 59 p. m.

11 4 p. m. 4 p. m. through 4: 59 p. m.

12 5 p. m. 5 p. m. through 5: 59 p. m.

13 6 p. m. 6 p. m. through 6: 59 p. m.

14 7 p. m. 7 p. m. through 7: 59 p. m.

15 8 p. m. 8 p. m. through 8: 59 p. m.

16 9 p. m. 9 p. m. through 9: 59 p. m.

17 10 p. m. 10 p. m. through 10: 59 p. m.

18 11 p. m. 11 p. m. through 11: 59 p. m.

19 12 Midnight 12 a. m. through 12: 59 a. m.

20 1 a. m. 1 a. m. through 1: 59 a. m.

21 2 a. m. 2 a. m. through 2: 59 a. m.

22 3 a. m. 3 a. m. through 3: 59 a. m.

23 4 a. m. 4 a. m. through 4: 59 a. m.

24 5 a. m. 5 a. m. through 5: 59 a. m.

* For some MOBILE6 hourly input parameters, overnight hours are grouped. Hourly inputs are representative of the same day or day type, but are reordered for input to MOBILE6 to start at 6 a. m. 38 Application of MOBILE6 Commands and Associated Input Parameters Tables 25 through 31 lists and describes all of the MOBILE6 commands that may affect calculating emissions factors ( excluding commands such as those that affect only the output format or content). Respectively, these seven tables are: MOBILE6 Pollutants and Emission Rates, MOBILE6 External Conditions, MOBILE6 Vehicle Fleet Characteristics, MOBILE6 Activity, MOBILE6 State Programs, MOBILE6 Fuels, and MOBILE6 Alternative Emissions Regulations and Control Measures. These tables identify the combinations of MOBILE6 commands and parameters used for this analysis.

Parameters associated with each MOBILE6 command are generally labeled as either EPA default, localityspecific or NOT APPLIED. The commands where the associated input parameters are labeled only as " EPA default" are generally not input for this analysis.

The procedures used to develop the locality specific inputs to MOBILE6 are detailed after the following seven MOBILE6 input category tables. 39 Table 25 MOBILE6 Pollutants and Emission Rates Command Function/ Description Input Parameter Source/ Value POLLUTANTS Defines the basic set of pollutants to report. NOT APPLIED. ( The MOBILE6 default is assumed: HC, CO, NOx.)

PARTICULATES Enables computation of particulate matter ( PM) an related emissions factors. NOT APPLIED.

PARTICULATE EF Specifies location of files that contain the particulate emissions factors when PARTICULATES command is used. NOT APPLIED.

PARTICLE SIZE Allows user to specify the maximum particulate size cutoff used by MOBILE. NOT APPLIED.

EXPRESS HC AS VOC One of five possible commands which allow the user to specify the particular HC species ( NMHC, NMOG, THC, TOG, VOC) to report in the exhaust emissions output. " VOC" command is applied. Only the command is required.

NO REFUELING Directs MOBILE6 not to calculate refueling emissions factors. This command is applied. Only the command is required.

AIR TOXICS Enables the computation of air toxic emissions factors ( six explicit pollutants) and specifies which to calculate. NOT APPLIED.

ADDITIONAL HAPS Allows entry of emissions factors or air toxic ratios for calculation of additional user defined air toxic pollutant emissions factors. NOT APPLIED.

MPG ESTIMATES Allows entry of alternate fuel economy performance data by vehicle class and model year. NOT APPLIED. ( MOBILE6 default values are assumed.) 40 Table 26 MOBILE6 External Conditions Command Function/ Description Input Parameter Source/ Value CALENDAR YEAR Identifies calendar year for which emissions factors are to be calculated. ( Required to run model). 1999, 2007, 2012.

EVALUATION MONTH Provides option of calculating January 1 or July 1 emissions factors for calendar year of evaluation. 7 ( for July)

MIN/ MAX TEMPERATURE Sets minimum and maximum daily temperatures. ( Required to run model if the HOURLY TEMPERATURES command is not used.) NOT APPLIED. ( See HOURLY TEMPERATURES.)

HOURLY TEMPERATURES Allows temperatures input for each hour of day. ( Required to run model if MIN/ MAX TEMPERATURE command is not used.) County group specific by episode day, developed by TCEQ. The hourly input sequence is 6 a. m. to 12 a. m. followed by 12 a. m. to 6 a. m. for the same day. See Appendix F.

ALTITUDE Specifies high or low altitude for modeling area. NOT APPLIED. ( EPA default, low altitude, is assumed).

ABSOLUTE HUMIDITY Used to specify daily average humidity ( directly affects NOx emissions). MOBILE6 also converts absolute humidity to heat index which affects HC and CO emissions for the portion of the fleet that MOBILE6 determines is using air conditioning. NOT APPLIED. ( See RELATIVE HUMIDITY.)

Environmental Effects on Air Conditioning:

CLOUD COVER PEAK SUN SUNRISE/ SUNSET Commands used by MOBILE6 to model the extent of vehicle air conditioning usage.

Specifies average percent cloud cover for given day. Specifies Mid day hours with peak sun intensity.

Allows user to specify time of sunrise and sunset. NOT APPLIED. ( EPA default assumed.) NOT APPLIED. ( EPA default assumed.) Region specific, 7 a. m. 8 p. m., TCEQ.

RELATIVE HUMIDITY Specifies use of 24 hourly relative humidity values entered by user. MOBILE6 will perform hourspecific calculations with hourly values rather than use single daily default absolute humidity value. County group specific by episode day, developed by TCEQ. The hourly input sequence is 6 a. m. to 12 a. m. followed by 12 a. m. to 6 a. m. for the same day. See Appendix F.

BAROMETRIC PRES Specifies use of user input daily average barometric pressure for use with hourly relative humidity to calculate hourly absolute humidity values. Used MOBILE6 default, 29.92 inches Mercury. 41 Table 27 MOBILE6 Vehicle Fleet Characteristics Command Function/ Description Input Parameter Source/ Value REG DIST Allows the user to supply registration distributions by age for any of the 16 composite ( combined gasoline and diesel) vehicle types. Locality Specific/ EPA default. Developed by TTI.

Mid year 2002 TxDOT county group registrations data are applied except for buses for which the MOBILE6 default is used. The age distributions are assumed to be the same for all evaluation years. See Appendix G.

DIESEL FRACTIONS Permits user to supply locality specific diesel fractions for 14 of the 16 composite vehicle categories by age. Locality Specific/ EPA default. Developed by TTI. Beginning in 2002, TxDOT midyear registrations specify gasoline and diesel fueled vehicles for the eight HDV classes. Mid year 2002 TxDOT statewide registrations are used to develop the HDV diesel fractions ( EPA defaults are applied for the remaining classes).

For future year evaluations, the latest diesel fractions ( 2002) are used for each calendar year up to the future year of evaluation ( e. g., 2003, 2004, 2005, 2006, 2007).

For 1999, diesel fractions are produced by dropping the 2000 and newer model year fractions from the 2002 diesel fractions data set, then applying the earliest model year fractions to each prior year back to the 25 years old and older category.

MILE ACCUM RATE Allows the user to supply the annual mileage accumulation rates by vehicle type and age. NOT APPLIED. ( EPA defaults are assumed   see technical report M6FLT. 007.)

NGV FRACTION Lets user specify percent of natural gas vehicles ( NGV) in the fleet by type and age certified to operate on either compressed or liquefied natural gas. NOT APPLIED. ( The EPA default percentage of NGV vehicles in the fleet, zero, is assumed.)

NGV EF Permits the user to enter alternate NGV emissions factors for each of the 28 vehicle types, for running and start emissions. NOT APPLIED. ( The EPA default, none, is assumed.) 42 Table 28 MOBILE6 Activity Command Function/ Description Input Parameter Source/ Value VMT FRACTIONS Used in MOBILE6 to weight the emissions of various vehicle types into average rates for groupings of vehicle classes. NOT APPLIED. ( EPA default assumed, used for aggregate results with no impact on this analysis. VMT mix is applied to link VMT outside MOBILE6 later in the process to calculate emissions by the 28 vehicle types.)

VMT BY FACILITY VMT fractions by MOBILE6 road type combine the four road type emissions factors into the " all road types" emissions factors. NOT APPLIED. ( EPA default assumed, used for aggregate results with no impact on this analysis.)

VMT BY HOUR Allows VMT fractions allocation by hour ofday applied in conversion of grams per hour ( g/ hr) to g/ mi, as well as in weighting of hourly g/ mi rates to obtain daily emissions factors. Region specific. The hourly travel fractions ( same as those used to distribute 24 hour link VMT by hour of day) are based on 1999 through 2001, September, SA/ MSA ATR counts. One set each is applied for Weekday, Friday, Saturday, and Sunday. The same fractions are used for all years. See Table 7.

SPEED VMT Allows user to allocate VMT by average speed ( 14 pre selected: 2.5 and 5 through 65 at 5 mph increments) for arterials and freeways for each hour of the day. Generic input. Same for all counties. Inputs are set up to calculate emissions factors by 14 MOBILE6 speed bin speed scenarios for MOBILE6 freeway and arterial road types.

AVERAGE SPEED Allows a single average speed for combined freeways and arterials for the entire day. NOT APPLIED.

STARTS PER DAY Lets user specify the average number of engine starts per vehicle per day by vehicle types for weekend days and weekdays. NOT APPLIED. ( Used EPA weekday and weekend day specific defaults   see technical report M6FLT. 003.)

START DIST Allows user to allocate engine starts by hour of the day for weekend days and weekdays. NOT APPLIED. ( Used EPA weekday and weekend day specific defaults   see technical report M6FLT. 003.)

SOAK DISTRIBUTION Allows use of alternate vehicle soak duration distributions for weekend days and weekdays. NOT APPLIED. ( Used EPA weekday and weekend day specific defaults   see technical reports M6FLT. 003 and 004.)

HOT SOAK ACTIVITY Allows users to specify a hot soak duration distribution for each of 14 daily time periods for weekend days and for weekdays. NOT APPLIED. ( Used EPA weekday and weekend day specific defaults   see technical reports M6FLT. 003 and 004.)

DIURN SOAK ACTIVITY Allows user set diurnal soak time distributions for each of 18 daily time periods. NOT APPLIED. ( The EPA defaults are assumed.   see technical report M6FLT. 006.)

WE DA TRI LEN DI Specifies alternate fractions of VMT that occur during trips of various durations at each hour of the average weekday. NOT APPLIED. ( The EPA defaults are assumed.   see technical report M6FLT. 005.)

WE EN TRI LEN DI Specifies hourly alternate fractions of VMT for trips of various lengths for weekend days. NOT APPLIED.

WE VEH US Directs MOBILE6 to use weekend activity data for calculating emissions factors. Applied command for weekend day analyses ( i. e., September 18, 19).

Table 29 43 MOBILE6 State Programs Command Function/ Description Input Parameter Source/ Value STAGE II REFUELING Allows modeling of at the pump refueling emissions. NOT APPLIED. Accounted for as an area source category.

ANTI TAMP PROG Allows user to model impacts of an ATP. NOT APPLIED. ( Although Texas administers a statewide ATP, ATP credit is only taken in those counties which also administer an enforced I/ M program.)

I/ M Commands: I/ M PROGRAM I/ M MODEL YEARS I/ M VEHICLES I/ M STRINGENCY I/ M COMPLIANCE I/ M WAIVER RATES I/ M CUTPOINTS I/ M EXEMPTION AGE I/ M GRACE PERIOD NO I/ M TTC CREDITS I/ M EFFECTIVENESS I/ M DESC FILE Required for exhaust/ evaporative I/ M programs. Required for exhaust/ evaporative I/ M programs. Required for exhaust/ evaporative I/ M programs. Required for exhaust. Do not use for evaporative. Required for exhaust. Optional for evaporative. Required for exhaust. Optional for evaporative. Optional for exhaust ( but required for IM240). Do not use with evaporative. Optional for both exhaust and evaporative. Optional for both exhaust and evaporative. Optional for exhaust. Do not use with evaporative. Optional for exhaust. Do not use with evaporative. Optional for both. NOT APPLIED. 44 Table 30 MOBILE6 Fuels Command Function/ Description Input Parameter Source/ Value FUEL PROGRAM Allows specification of one of four options: 1) Conventional Gasoline East Tier2 sulfur phase in schedule ( includes Texas), 2) Reformulated Gasoline ( RFG), 3) Conventional Gasoline West Tier2 sulfur geographical phase in area schedule, or 4) Sulfur content for gasoline after 1999. Option 1: Applied for all counties and evaluation years.

SULFUR CONTENT ( or GASOLINE SULFUR) Allows use of alternate sulfur content for conventional gasoline through calendar year 1999. Actual estimated value for 1999: 447 ppm, based on AAMA summer 1999 San Antonio sample survey data ( ERG, October 2002).

DIESEL SULFUR Allows use of ave. diesel fuel sulfur level for all calendar years. Required if PARTICULATES command is used. No affect on HC, CO, NOx, air toxics ( except if calculated as ratio to PM). NOT APPLIED.

OXYGENATED FUELS Allows modeling of oxygenated gasoline effects on exhaust for all gasoline fueled vehicle types. Not for use with AIR TOXICS command. NOT APPLIED.

FUEL RVP Allows user to specify fuel RVP for area being modeled ( required to run model). Actual estimated value for 1999, based on AAMA summer 1999 San Antonio sample survey data ( ERG, October 2002). Regulated limit ( 7.8 psi) less 0.2 compliance safety margin is applied for 2002 + analysis years 1999: 7.6 psi ( survey based) 2002 +: 7.6 psi ( regulated limit with 0.2 safety margin)

SEASON Identifies effective season for RFG calculation regardless of month modeled. NOT APPLIED.

GAS AROMATIC% Only when AIR TOXICS command is used. NOT APPLIED.

GAS OLEFIN% Only when AIR TOXICS command is used. NOT APPLIED.

GAS BENZENE% Only when AIR TOXICS command is used. NOT APPLIED.

E200 Only when AIR TOXICS command is used. NOT APPLIED.

E300 Only when AIR TOXICS command is used. NOT APPLIED.

OXYGENATE Only when AIR TOXICS command is used. NOT APPLIED.

RVP OXY WAIVER Only when AIR TOXICS command is used. NOT APPLIED.

Table 31 45 MOBILE6 Alternative Emissions Regulations and Control Measures Command Function/ Description Input Parameter Source/ Value NO CLEAN AIR ACT Models vehicle emissions as if the Federal Clean Air Act Amendments of 1990 had not been implemented. Applied for Pre 90 control analyses for all years except 1990.

HDDV NOx Off Cycle Emissions Effects: NO DEFEAT DEVICE NO NOX PULL AHEAD NO REBUILD REBUILD EFFECTS Turns off the effects of the HDD vehicle NOx offcycle emissions effects ( defeat device emissions). Turns off HDD NOx emissions reduction effects of Pull Ahead program. Turns off HDD NOx emissions reduction effects of Rebuild program. Allows user change Rebuild program effectiveness rate. NOT APPLIED.

NOT APPLIED.

NOT APPLIED.

1999: 0.01 ( TCEQ 2001 estimate is assumed), 2007, 2012: 0.90 ( EPA default is assumed).

Tier 2 Emission Standards and Fuel Requirements:

NO TIER2 T2 EXH PHASE IN T2 EVAP PHASE IN T2 CERT Allow the overriding of the default Tier 2 emissions standards and fuel requirements settings.

Disables Tier 2 requirements. Allows alternate Tier 2 exhaust standard phase in schedules. Allows alternate Tier 2 evaporative standard phasein schedules. Allows user to specify alternate Tier 2 50,000 mile certification standards. NOT APPLIED.

94+ LDG IMPLEMENTATON Allows use of alternate 1994 and later fleet penetration fractions for LDGVs under the Tier 1, NLEV ( or California LEV 1), and Tier 2 emissions standard programs. NOT APPLIED.

NO 2007 HDDV RULE Disables 2007 HDV emissions standards. NOT APPLIED.

External Conditions MOBILE6 local inputs for hourly temperatures, daily average humidity, and sunrise and sunset times were developed from September 1999 ozone episode data and applied based on " local time." TCEQ developed the values and TTI formatted them for input to MOBILE6.

Temperatures ( HOURLY TEMPERATURES Command) TCEQ developed one set of ambient hourly temperatures ( degrees Fahrenheit) for input to 46 MOBILE6 for the four county MSA based on weather data averaged from five Bexar County monitoring stations. The data sources are the EPA Aerometric Information Retrieval System ( http:// www. epa. gov/ airs), and the National Weather Service ( http:// www. nws. noaa. gov). Hourly temperatures from the stations for the modeling period were averaged within each hour.

The ozone episode modeling period for the SA/ MSA is September 13, 1999 through September 20, 1999. Since the emissions estimation method calls for emissions estimates for four day types as opposed to for individual episode days, temperature data were selected from the modeling period to correspond with the day type being modeled. The average weekday episode day was chosen as September 20 ( a Monday). The Friday, Saturday, and Sunday episode days were chosen as September 17, September 18 and September 19, respectively.

The temperatures were sequenced as required for input to MOBILE6 starting with the 6 a. m. hour. The temperatures are a MOBILE6 command file input. The same hourly temperatures were used for all analysis years. A summary of the temperature inputs are in Appendix F.

Relative Humidity ( RELATIVE HUMIDITY Command) The RELATIVE HUMIDITY command was applied to specify local hourly percent relative humidity values for the MSA.

The hourly relative humidity inputs were developed following the same procedure as described above for the hourly temperature input development, except that humidity data were used from only one Bexar County weather station ( San Antonio International Airport). The humidity parameter is input in the MOBILE6 command file. The humidity values used ( one set for each episode day for the MSA for all evaluation years) are summarized in Appendix F.

Sunrise and Sunset Times ( SUNRISE/ SUNSET Command) The SUNRISE/ SUNSET command allows the user to specify the time of sunrise and sunset. This feature affects only the air conditioning correction. TCEQ provided the sunrise and sunset times, which are the same for the MSA for all evaluations. The times were developed using data from the city of San Antonio. The data source is the U. S. Naval Observatory Astronomical Applications Department Internet site ( http:// aa. usno. navy. mil/). The times are 7 a. m. and 8 p. m. local time.

Vehicle Fleet Characteristics Vehicle registration ( age) distributions and diesel fractions inputs to MOBILE6 were developed from TxDOT midyear 2002 county vehicle registration data for those vehicle types where TxDOT registrations data were available. EPA defaults were used where necessary. Due to sparse registration data for some vehicle classes resulting from the increased disaggregation level of the vehicle classifications in MOBILE6 ( 28 vehicle types versus the previous eight vehicle class scheme), the registrations data are grouped for the four county MSA for developing the age distributions input, and grouped for the state for developing the diesel fractions inputs.

The application of local registration distributions and diesel fractions for these EI forecasts follows guidance in Technical Guidance on the Use of MOBILE6 for Emission Inventory Preparation ( EPA, January 2002). Namely, this analysis uses the latest available registration data for estimating vehicle class age distributions, and uses the most recent diesel fractions available as the projected fractions for future years.

Vehicle Registration Distributions ( REG DIST Command) Table 32 shows the user supplied vehicle registration distributions input to MOBILE6 by vehicle age for any of the 16 composite ( combined gas and diesel) vehicle types. EPA default distributions are internally applied by MOBILE6 for vehicle classes where the user does not provide alternate values. The input values for each vehicle class are 25 age fractions representing the fraction of vehicles by age for that particular vehicle class as of July of the evaluation year. These age fractions start with the evaluation year as the 1st age fraction and work back in annual increments to end with the 25th fraction, which represents the fraction of vehicles of age 25 years and older. The fractions are calculated as the model year specific registrations in a class divided by the total vehicles registered in that class. 47 Table 32 Composite Vehicle Classes for Vehicle Registration Data ( REG DIST Command)

Number Abbreviation Description 1 LDV Light Duty Vehicles ( Passenger Cars)

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

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

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

5 LDT4 Light Duty Trucks 4 ( 6,001 8,500 lbs. GVWR, 5,751 lbs. and greater ALVW)

6 HDV2B Class 2b Heavy Duty Vehicles ( 8,501 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 Buses 15 HDBT Transit and Urban Buses 16 MC Motorcycles ( All)

Source: MOBILE6 User's Guide ( EPA, January 2002).

TTI developed MOBILE6 age distributions fractions input from TxDOT data for all vehicle types except for the two bus categories. EPA defaults were used for the two bus categories. To develop these distributions, TTI used two county level data sets provided by TxDOT. The TxDOT registrations data provided are summarized as:

· July 2002 registrations for: LDV, LDT12, LDT34, MC, HDGT, HDDT; and · July 2002 registrations for: Gas: HDV2B, HDV3, HDV4, HDV5, HDV6, HDV7, HDV8A, HDV8B; and Diesel: HDV2B, HDV3, HDV4, HDV5, HDV6, HDV7, HDV8A, HDV8B.

The July 2002 registrations are for: automobiles, light duty trucks ( LDT12, corresponding to MOBILE6 classes LDT1 and LDT2 ), heavier light duty trucks ( LDT34, corresponding to MOBILE6 classes LDT3 and LDT4), motorcycles, heavy duty gas trucks ( > 8,500 lbs. GVWR), and heavy duty diesel trucks ( > 8,500 lbs. GVWR). The July 2002 gasoline and diesel HDV classes ( eight each) comprise the July 2002 HDGT and HDDT classes represented in the July 2002 data set, respectively, and correspond to the eight HDV weight classes for numbers six through 13 in Table 32.

First the county registrations data for the four MSA counties were combined. There are three main steps to developing the MOBILE6 registration distributions input for the 14 non bus vehicle classes. The first step in the process develops the July 2002 registrations by the 25 age groups for 12 of the 16 composite ( by fuel) vehicle 48 classes ( eight HDV, LDV, LDT12, LDT34, MC). The second step converts the registrations from numbers of vehicles registered, to fractions registered by age for each of these 12 classes. The registrations are then expanded from 12 to 14 vehicle classes.

The 16 HDV class registrations were combined into the MOBILE6 eight composite ( gas and diesel) classes by summing the individual fuel type registrations by age within each weight category. The 1978 and older registrations were summed to yield the " age 25 and older" registrations for each of the 12 composite vehicle classes ( i. e., the eight HDV classes plus LDV, LDT12, LDT34, and MC).

The conversion of the registrations from numbers of vehicles to fractions of vehicles by age was made for each vehicle class by dividing the registrations for each age by the total registrations. MOBILE6 requires that the age distribution fractions for each vehicle class sum to one. In this step the age distribution fractions for each class were summed. For sums not equal to one ( due to rounding error), the largest registration fraction was adjusted to make the fractions sum to one.

The resulting July 2002 estimated SA/ MSA registration distribution fractions for the 12 composite classes were then expanded to 14 classes. This was accomplished by using the LDT12 age fractions, for both the MOBILE6 LDT1 and LDT2 classes and the LDT34 age fractions for both the MOBILE6 LDT3 and LDT4 classes. The MOBILE6 vehicle registration distributions are input from external data files. The external data files are on CDROM Appendix A lists the data files. Appendix G shows the registration distributions input.

Diesel Fractions ( DIESEL FRACTIONS Command) The DIESEL FRACTIONS command allows the user to specify diesel fractions for 14 of the 16 composite ( gasoline and diesel) vehicle categories by vehicle age. MOBILE6 assumes that urban/ transit buses are 100 percent diesel, and that motorcycles are all gasoline fueled, so these two categories do not require diesel fractions. The diesel fraction represents the portion of diesels in a composite ( gasoline and diesel) vehicle class for any vehicle age. When the user enters diesel fractions, all 14 sets of fractions are required. Each set of fractions contains the diesel fractions for 25 vehicle ages from the evaluation year back through the 25th fraction, which represents vehicle ages of 25 years and older.

The MOBILE6 default fractions vary by age for model years 1972 through 1996. For 1971 and earlier model years, the default diesel fractions are assumed the same as the 1972 model year fractions. For the 1997 and later model years, the default diesel fractions are assumed the same as the 1996 model year fractions.

TTI developed evaluation year specific, state level diesel fractions inputs for the analysis. One individual statelevel set of diesel fractions was developed for each evaluation year. TTI used a combination of estimated TxDOT diesel fractions and EPA default diesel fractions for modeling the emissions factors. Table 33 shows the MOBILE6 diesel fractions input categories with corresponding data sources. The diesel fraction estimates were calculated based on TxDOT individual diesel and gasoline vehicle registrations for the eight HDV ( HDV2b through HDV8b) weight classes. To produce the HDV diesel fractions by model year, the diesel registrations were divided by the sum of the gasoline and diesel registrations, by HDV composite vehicle class, and model year.

The HDV diesel fractions were forecast from 2002 to 2007 ( and to 2012) by applying the latest diesel fraction ( 2002) to each of the future years ( e. g., 2003 through 2012). To estimate the 1999 base year diesel fractions, the diesel fractions for 2000, 2001, and 2002 model years were dropped from the data set; the fractions for oldest model year in the data set, 1978, were applied to each of the older model years to complete the data set for 25 model years. The 1999, 2007 and 2012 estimated HDV diesel fractions were then combined with the corresponding evaluation year specific July EPA default diesel fractions for the remaining vehicle classes to produce the complete input data set for each evaluation year. Diesel fractions are entered in the MOBILE6 command file. Appendix G shows the diesel fractions input for each evaluation year. 49 Table 33 Source of Diesel Fractions for Composite Vehicle Types ( DIESEL FRACTIONS Command)

Number Abbreviation Description Source of Fractions 1 LDV Light Duty Vehicles EPA MOBILE6 Evaluation Year Default 2 LDT1 Light Duty Trucks 1 EPA MOBILE6 Evaluation Year Default 3 LDT2 Light Duty Trucks 2 EPA MOBILE6 Evaluation Year Default 4 LDT3 Light Duty Trucks 3 EPA MOBILE6 Evaluation Year Default 5 LDT4 Light Duty Trucks 4 EPA MOBILE6 Evaluation Year Default 6 HDV2B Class 2b Heavy Duty Vehicles TxDOT July, 2002 Statewide Registrations 7 HDV3 Class 3 Heavy Duty Vehicles TxDOT July, 2002 Statewide Registrations 8 HDV4 Class 4 Heavy Duty Vehicles TxDOT July, 2002 Statewide Registrations 9 HDV5 Class 5 Heavy Duty Vehicles TxDOT July, 2002 Statewide Registrations 10 HDV6 Class 6 Heavy Duty Vehicles TxDOT July, 2002 Statewide Registrations 11 HDV7 Class 7 Heavy Duty Vehicles TxDOT July, 2002 Statewide Registrations 12 HDV8A Class 8a Heavy Duty Vehicles TxDOT July, 2002 Statewide Registrations 13 HDV8B Class 8b Heavy Duty Vehicles TxDOT July, 2002 Statewide Registrations 14 HDBS School Buses EPA MOBILE6 Evaluation Year Default Activity The locality specific activity parameters used to develop the hourly emissions factors are fleet hourly VMT fractions ( through the VMT BY HOUR command).

Additional non default activity inputs to the model were hourly fractions of VMT by the 14 speeds for Arterials and Freeways ( SPEED VMT command). Weekend day hourly vehicle usage rates ( MOBILE6 defaults) for particular activity input parameters ( through the WE VEH US command) were applied for the Saturday and Sunday episode days.

VMT Fractions ( Also Known as VMT mix) These sets of fractions ( VMT fractions attributable to individual vehicle classes) are an input to MOBILE6, however, the method for this study calls for the application of the VMT mix ( or mixes) later in the emissions calculation process. VMT mix development was discussed previously in this documentation.

Total VMT by Hour ( VMT BY HOUR Command) Hourly fleet total VMT distributions are input to MOBILE6 by using the VMT BY HOUR command. These fractions are used by MOBILE6 to convert the units of the non travel related hourly emissions factors ( e. g., hot soak, diurnal, start, etc.) to units of g/ mi. ( The VMT by hour fractions are also used to produce the daily emissions factors as composites of the hourly emissions factors.)

Development of the hourly travel fractions for the TxDOT SA/ MSA were previously discussed in the " Hourly Travel and Directional Factors" section. These same hourly fractions, used to distribute HPMS VMT by hour of day, are applied as input to MOBILE6. The only differences are in sequence ( MOBILE6 hourly input starts with the 6 a. m. fraction) and format. 50 To summarize, TxDOT continuous ATR data ( for 1999 and 2001) are aggregated within the SA/ MSA for developing the San Antonio area hourly travel factors. Hourly travel factors are developed for each of the four day types. Using the day type specific volumes, these factors are the ratio of hourly volumes to 24 hour volume.

These fractions are input to MOBILE6 as an external data file. There is one set of four day type specific hourly VMT fractions files used for all evaluation years. Table 7 shows the hourly travel factors. The MOBILE6 external data files are included on CD ROM, as described in Appendix A.

VMT Distribution by Average Speed on Freeways and Arterials ( SPEED VMT Command) The VMT distributions by average speed inputs are called by the SPEED VMT command, but are accommodated internally by the POLFAC62 program ( that is, no user speed input commands or data parameter values are required when producing MOBILE6 emissions factors tables with POLFAC62). POLFAC62 uses the SPEED VMT inputs to produce the individual Freeway and Arterial emissions factors indexed by the 14 MOBILE6 speed bin speeds.

There are 14 scenarios, each with 100 percent of Freeway and Arterial VMT set to one of the 14 MOBILE speed bin speeds. Each scenario produces a set of Arterial and Freeway emissions factors corresponding to one of the 14 speeds.

Weekend Day Vehicle Usage ( WE VEH US Command) MOBILE6 supplies default weekend day hourly vehicle usage rates for start distributions, soak distributions, hot soak activity, and trip length distributions. For Saturday and Sunday day types the WE VEH US command was applied to model the EPA default weekend usage rates for these parameters ( MOBILE6 uses only the default weekday trip length distributions for both weekday and weekend day types).

State Programs There are no MOBILE6 State Programs descriptive inputs ( i. e., I/ M, ATP, and stage II refueling programs) modeled.

Fuels   Locality Specific Inputs to MOBILE6 User input for fuel effects modeling for the SA/ MSA evaluations are the FUELS PROGRAM, FUEL RVP and GASOLINE SULFUR commands and associated input parameters and options. These inputs are entered in the MOBILE6 command file. The MSA is modeled with conventional gasoline. Fuel Program ( FUEL PROGRAM Command) The MOBILE6 FUEL PROGRAM command provides the user four options for modeling fuels effects. The conventional gasoline east option ( option 1) is used for this analysis. This option supplies post 1999 gasoline sulfur levels by year under the Tier 2 rule phase in schedule for most states ( including Texas).

Gasoline RVP ( FUEL RVP Command) Gasoline RVP is a required user input to MOBILE6 with the FUEL RVP command. For developing modeling emissions inventories, estimated actual RVPs from gasoline sample survey data from the modeling area and episode day are used when available.

MSA specific gasoline sample survey data were available for developing estimated actual gasoline RVP inputs for this analysis. Actual RVP estimates developed by Eastern Research Group, Inc. ( ERG) for the purpose of updating existing EPA National Toxic Inventory ( NTI) estimates ( see County Specific Fuel Parameters for 1990, 1996, and 1999 Toxic Emissions Modeling [ Preparation for MOBILE6.2 model Runs], ERG, October 2002) were available for 1999. The summer 1999 estimated RVP value, 7.6 psi, is based on Alliance Automobile Manufacturers North American ( AAM) Gasoline and Diesel Fuel Survey data from summer 1999 gasoline sample surveys conducted in the city of San Antonio. This 7.6 psi estimated actual RVP value was used for the SA/ MSA for all evaluation years.

The 7.6 psi value was used for 2007 and 2012 analysis years assuming a compliance safety margin of 0.2 psi ( value of actual RVP below the regulated RVP limit, which is 7.8 psi starting in 2000). This compliance safety margin for the future year analyses is a conservative estimate in comparison to the 1999 compliance safety margin estimate ( 9.0 psi regulated limit minus 7.6 psi estimated actual equals 1.4 psi under the limit). It would be 51 unreasonable to assume the 1999 1.4 psi estimated compliance safety margin under the new 7.8 psi limit, which would result in a 6.4 psi estimated actual RVP value. Thus, based on these data, the conservative assumption was made that the future year RVP under the 7.8 psi limit should be at least as low as the 1999 estimated actual RVP value under the 9.0 psi limit.

Gasoline Sulfur Content ( GASOLINE SULFUR Command) For 1999 and earlier evaluation years, MOBILE6 allows alternate input for gasoline sulfur content through use of the GASOLINE SULFUR command. The MOBILE6 default is 300 parts per million ( ppm) sulfur for 1999 and earlier years.

For the summer 1999 analysis, the estimated actual gasoline sulfur content, 447 ppm, was input to MOBILE6 with the GASOLINE SULFUR command. This summer 1999 estimated actual gasoline sulfur content value is from the fuel parameters input data developed by ERG for updating the EPA 1999 NTI. The values are based on summer 1999 AAM San Antonio gasoline sample survey data.

For 2007 and 2012 evaluation years, the MOBILE6 default gasoline sulfur content values are used. These values correspond to the Tier 2 sulfur phase in schedule ( set by using the FUEL PROGRAM command with Option 1, discussed above). MOBILE6 Alternative Emissions Regulations and Control Measures The only user input value applied within this section of MOBILE6 commands, is related to the HDDV NOx offcycle emissions effects.

In the late 1980s and most of the 1990s, HDDV engines were built with " defeat devices" allowing in use engine emissions to be higher than emissions as specified under Federal Test Procedure conditions. MOBILE6 includes estimates of these excess HDDV emissions as well as the emissions offsetting effects of two programs   early pullahead of 2004 HDDV emissions standards, and low emissions rebuilds of existing engines.

Information from EPA led to the conclusion that the best estimate for the low NOx emissions rebuilds program effectiveness rate for the 1999 evaluation is 1.0 percent. The EPA information showed that the number of low NOx rebuild kits installed ( as of January, 2002) in the affected population was 0.97 percent. The 1.0 percent effectiveness rate is assumed for 1999, however, no information was available to justify a non default rebuild effects input value for 2007, and 2012.

Thus, for each evaluation year, the effectiveness rates were set as follows:

· 1999 Rebuild Program effectiveness rate: 1.0 percent; and · 2007+ Rebuild Program effectiveness rate: 90.0 percent.

The 90 percent effectiveness value used for the 2007 and 2012 evaluations is the EPA's estimate, which is applied as the MOBILE6 default. This value and its associated command, REBUILD EFFECTS, are inputs to the MOBILE6 command file.

Emissions Factor Post Processing Requirements and Procedures There is one limitation of the MOBILE6 model that results in an emissions factors post processing requirement for this analysis   MOBILE6 user specified alternate diesel fuel parameters are not available for computing the VOC, CO, and NOx emissions factors.

To model the impacts of Texas LED, MOBILE6 diesel vehicle emissions factors were post processed ( with the RATADJV6 program, described in Appendix B). The NOx adjustment factor of 0.943 was multiplied by all of the diesel fueled vehicle MOBILE6 2007 and 2012 NOx emissions factors. This adjustment corresponds to a reduction in NOx emissions factors of 5.7 percent. Development of this value is documented in the ERG report, Revised SIP 52 Modeling Procedures for the HGA Nonattainment Area, included as Appendix G of Houston/ Galveston Attainment Demonstration and Post 1999 Rate of Progress SIP, TNRCC, October 2001.

On completion of the post processing for LED, the emissions factors are ready for input to the emissions estimation program. The emissions factors output files are included on the CD ROM. See Appendix A for file names and descriptions.

EMISSIONS CALCULATIONS Hourly emissions were calculated by county for each of the four episode days using the IMPSUM62 program ( see description in Appendix B). With the day of week specific VMT and emissions factors ( g/ mi) for each hour, emissions were calculated for each of the 28 vehicle types and each of 14 pollutant specific emissions types by direction on each link ( i. e. TDM network links and HPMS virtual links).

For each evaluation year and day, 108 files were output from the emissions calculations: 96 hourly linkemissions files ( 24 hours multiplied by four counties), four summary files of county level hourly and 24 hour emissions estimates cross classified by vehicle type and road type ( one for the TDM network county and one each for the three HPMS based counties), a tab delimited version of each of the four emissions summary files, and an emissions calculation program execution log file corresponding to each of the four emissions summary files. These files are included on the CD ROM ( see Appendix A).

Hourly Link Emissions For each county and analysis day type, the emissions were calculated by hour for each link using the following basic inputs:

· MOBILE6 hourly Freeway, Arterial, and Ramp emissions factors indexed by speed for 28 vehicle types, developed with POLFAC62 ( and RATEADJV6 program for postprocessed rates);

· records associating the MOBILE6 Freeway emissions factors to the freeway links, and the MOBILE6 Arterial emissions factors to the non freeway links ( excluding Ramps), and MOBILE6 Ramp emissions factors to the TDM network links coded as Ramp;

· link specific operational VMT and speed estimates as developed ( for each hour) for TDM network and added intrazonal links ( or HPMS virtual links) using the PREPIN program to include: A node ( HPMS area type code), B node ( HPMS functional class code), county number, functional classification code ( HPMS area type and functional class cross combination code), link length ( HPMS center lane miles), congested speed, and VMT; and · VMT mix ( to allocate link VMT by each of the 28 vehicle types) by time period and roadway type.

For each hour, the emissions estimates were computed by vehicle type for each link. The emissions factors, discussed previously, were tabulated in look up tables by hour, road type ( drive cycle), vehicle type, and 14 speeds ( 2.5 mph and 5 mph to 65 mph at 5 mph intervals) for the four county SA/ MSA. MSA level, 24 hour VMT mix correlated to day type and functional classification group, were multiplied by the fleet total link VMT to produce hourly link VMT estimates by the 28 vehicle types. Emissions factors were then matched with link level VMT based on county, speed, road type, hour, and vehicle class. Emissions factors for link speeds that are not represented in the set of 14 MOBILE6 speed bin speeds were calculated by interpolation ( see example calculation, Appendix B). For link speeds greater than or less than the MOBILE6 bounding speeds of 65 mph and 2.5 mph, the emissions factors corresponding to those bounding speeds were used, respectively. The link VMT were then multiplied by the emissions factors to produce the link level emissions estimates in grams. 53 Tables 34 and 35 show the correlation of the functional classes to the MOBILE6 drive cycles and to the VMT mix functional classification groups, as used in the emissions calculations for the TDM network counties and the HPMS based counties, respectively.

Table 34 San Antonio TDM Network Functional Class Groupings for Allocation of VMT Mix and MOBILE6 Drive Cycle Emissions Factors MOBILE6 Drive Cycle Functional Class Name VMT Mix Functional Group Radial Freeway Expressway Circular Freeway Freeway HOV* Freeway Ramp Ramp Radial Parkway Primary Arterial Divided Primary Arterial Undivided Minor Arterial Divided Minor Arterial Undivided Circular Parkway Circular Arterial Undivided Arterial Collectors Divided Collectors Undivided Centroid Connector Arterial Intrazonal Collector/ Local * Used only for 2015 network ( 2012 emissions analysis). 54 Table 35 HPMS Functional Class Groupings for Allocation of VMT Mix and MOBILE6 Drive Cycle Emissions Factors MOBILE6 Drive Cycle HPMS Functional Class VMT mix Functional Group Interstate Freeway Freeway Freeway Other Principal Arterial Minor Arterial Arterial Major Collector Minor Collector Arterial Local Collector For each evaluation year and episode day, county level, hourly link emissions files were produced. The linkemissions file data elements for each TDM network ( and intrazonal) link are: A node, B node, functional class code, pollutant specific emissions type label, and emissions estimates ( grams) for each of the 28 vehicle types. The HPMS based county link emissions output data elements are the same except for the first three, which are: HPMS functional classification number, HPMS area type number, and HPMS area type and functional class cross combination code ( See Appendix A).

Day of Week Hourly and 24 hour Emissions Summaries For each analysis day, by individual county, the link emissions estimates were summed for each hour, and the hourly emissions were summed for each day. The resulting composite VOC, CO, and NOx emissions estimates are summarized in pounds by road type, vehicle type, and road type and vehicle type cross classification. VMT, VHT, VMT weighted speeds, and other inventory data are included with the emissions summaries. These files (*. LST and a tab delimited version, *. TAB) are included with the set of data files provided on CD ROM ( see Appendix A). 56 APPENDIX A ELECTRONIC SUBMITTAL DATA SET NAMES AND DESCRIPTIONS 58 SA/ MSA 1999, 2002, 2005, 2007, AND 2012 COUNTY EMISSIONS INVENTORIES ELECTRONIC SUBMITTAL DATA SET NAMES AND DESCRIPTIONS The emissions inventories ( EI) for the SA/ MSA include one TDM network based county ( Bexar), and three HPMSbased counties ( Comal, Guadalupe, and Wilson). The EIs are for four September 1999 episode days ( a Weekday [ average Monday through Thursday], Friday, Saturday, and Sunday) for each county and evaluation year. This appendix describes the EI data set files that are provided on CD ROM along with this Technical Note.

Although the HPMS based EIs are not network link based, the hourly emissions files are produced in the network link emissions file format, and are referred to as link emissions files. Network link coordinates are provide for the TDM based counties; no coordinates are provided for the HPMS based county data.

CD ROMs The EI data are contained on seven CD ROMs. There are six CD ROMs that contain the link emissions files and EI summary files; and one CD ROM that contains the MOBILE6 input/ output files, the network link coordinates and a copy of this electronic submittal data description.

Link Emissions File Formats and Data Definitions Tables 36 through 42 show the link emissions file format and data definitions. Emissions are not gridded; coordinates are included for the travel demand model network links.

TDM Network Node Coordinates The TDM network node coordinate files are zipped ( in coord. zip) on the CD ROM named " SA_ EF_ XY". The specifications of the coordinates when imported into TRANSCAD are:

· Class  North America NAD27 ( U. S. State Plane); and · Zone  TxDOT : Texas Statewide Mapping System.

The node ID, Longitude, and Latitude are provided for the 1999, 2007, and 2015 network nodes ( link ends) in the following files:

· 1999 network: SanAnt99coord. txt; · 2007 network: SanAnt07coord. txt; and · 2015 network: SanAnt15coord. txt.

Emissions Data: There are two CD ROMs ( a and b) for each analysis year ( six CD ROMs total). Each CD ROM contains one zip file with about half of the data for a particular evaluation year. The CD ROM names are " SAYY#_ EM", where YY = 99, 07, 12 corresponding to analysis year; # = a, b corresponding to half a year's data. Each set of CD ROMs ( i. e., a and b) includes:

· county level hourly link emissions files ( 24 hours for each of the four counties for each of the four days = 384 ASCII files, with . T01, . T02.... T24 extensions); · IMPSUM62 county level hourly emissions inventory data summaries to include VMT mix, VMT, VHT, average speed, and emissions cross classified by vehicle type and road type; SUMALL62 county level 24 hour emissions inventory data summaries ( one ASCII file per TDM network and one ASCII file per HPMS based county for each of the four day types = 16 files, with . LST extension);

· tab delimited version of second bullet above ( 16 ASCII files with . TAB extension); and · log of emissions estimation program runs ( 16 ASCII files with . LOG extension). 59 Data set file names are:

countyname_ sepyyddd_ emis. Thr; SAsepyyddd_ ntwk. LOG; Hcountyname_ sepyyddd. LOG; SAsepyyddd_ ntwk. LST; Hcountyname_ sepyyddd. LST; SAsepyyddd_ ntwk. TAB; and Hcountyname_ sepyyddd. TAB.

Where:

countyname is the county name; yy is the last two digits of the evaluation year; ddd is the day type: WKD, FRI, SAT, or SUN; hr is 01... 24 representing the hours 12 a. m. through 11 p. m. ( local time); SA stands for the San Antonio area TDM network; and Hcountyname is the county name for HPMS based counties ( Comal, Guadalupe, and Wilson).

Emissions Factor Data: The four county SA/ MSA emissions factors input/ output files are on the CD " SA_ EF_ XY." One zip file, SA_ EF99_ 12. zip, contains 43 files that comprise all of the emissions factor inputs an outputs. The files include MOBILE6 command and external data files, interim and final hourly emissions factors, interim and final daily emissions factors, modeling run logs and MOBILE6 descriptive output listings. 60 File Naming Conventions Input files are:

ddsepyyDT_ SA. in ( 12 command input files); SAmsa02. rgd ( one MSA level registration distribution file); and SA_ dd. vhr ( four MSA level hourly VMT files, one per day type).

Final hourly emissions factor table output files are:

ddsepfyDT_ SA. rat ( four files, one per day type for 1999); and ddseplyDT_ SA_ led. rat ( eight files, one per day type each for 2007 and 2012 adjusted for LED).

Interim hourly emissions factor table output files are:

ddseplyDT_ SA. rat ( eight hourly tables, one per day type each for 2007 and 2012 prior to lowemissions diesel fuel adjustment procedure).

Daily emissions factor tables output files are:

same as above ( 20) hourly files, except with the ". rtd" extension in place of ". rat."

LOG and LST output files:

saEAC_ sepyy_ RT. LOG ( three emissions factor run log files, one per evaluation year); and saEAC_ sepyy_ RT. LST ( three files with MOBILE6 scenario descriptive output**).

Where:

yy is the last two digits for each of the three evaluation years; dd is the day date for each of the four episode days; fy is the last two digits of the first evaluation year: 1999; ly is the last two digits of the last two evaluation years: 2007, 2012; and DT is day type represented by: WK, FR, SA, and SU.

* Note that the " Daily ALL" emissions factors ( network average daily emissions factors) in the . rtd files are meaningless for this analysis ( because they are composited based on the MOBILE6 default VMT BY FACILITY). From the daily emissions factor files, only the road type specific ( i. e., individual drive cycle) daily emissions factors ( FRWY, ART, LOC, and RAMP) are valid. ** The descriptive MOBILE6 output is useful as a check of inputs ( some of which are listed in the descriptive output) but not for the emissions factors themselves which composites based on MOBILE6 default VMT BY FACILITY values. 61 Table 36 Link Emissions Data Fields for HPMS based Counties Abbreviation Columns Format Type Description HPMS Area Type 1  6 I6 HPMS Area Type Code ( 1 3) ( see Table 39).

HPMS Functional Class 7  12 I6 HPMS Functional Class Code ( 1 7) ( see Table 40).

FC 13  15 I3 Functional Classification of Link ( see Table 41).

EMISS 17  19 A3 " VOC," or " CO," or " NOx"

ETYPE 21  31 A11 Emissions sub component type ( see Table 44).

LDGV 32  41 F10.?* LDGV link emissions in grams LDGT1 42  51 F10.? LDGT1 link emissions in grams LDGT2 52  61 F10.? LDGT2 link emissions in grams LDGT3 62  71 F10.? LDGT3 link emissions in grams LDGT4 72  81 F10.? LDGT4 link emissions in grams HDGV2B 82  91 F10.? HDGV2B link emissions in grams HDGV3 92  101 F10.? HDGV3 link emissions in grams HDGV4 102  111 F10.? HDGV4 link emissions in grams HDGV5 112  121 F10.? HDGV5 link emissions in grams HDGV6 122  131 F10.? HDGV6 link emissions in grams HDGV7 132  141 F10.? HDGV7 link emissions in grams HDGV8A 142  151 F10.? HDGV8A link emissions in grams HDGV8B 152  161 F10.? HDGV8B link emissions in grams LDDV 162  171 F10.? LDDV link emissions in grams LDDT12 172  181 F10.? LDDT12 link emissions in grams HDDV2B 182  191 F10.? HDDV2B link emissions in grams HDDV3 192  201 F10.? HDDV3 link emissions in grams HDDV4 202  211 F10.? HDDV4 link emissions in grams HDDV5 212  221 F10.? HDDV5 link emissions in grams HDDV6 222  231 F10.? HDDV6 link emissions in grams HDDV7 232  241 F10.? HDDV7 link emissions in grams HDDV8A 242  251 F10.? HDDV8A link emissions in grams HDDV8B 252  261 F10.? HDDV8B link emissions in grams MC 262  271 F10.? MC link emissions in grams HDGB 272  281 F10.? HDGB link emissions in grams HDDBT 282  291 F10.? HDDBT link emissions in grams HDDBS 292  301 F10.? HDDBS link emissions in grams LDDT34 302  311 F10.? LDDT34 link emissions in grams * The F10? format is either F10.0, F10.1, F10.2, F10.3, or F10.4. The format selected for a field is based on the value of the field. 62 Table 37 HPMS Area Type Codes HPMS Area Type Code Description 1 Rural 2 Small Urban 3 Urban Table 38 HPMS Functional Classification Codes HPMS Functional Class Code Description 1 Interstate 2 Freeway 3 Other Principal Arterial 4 Minor Arterial 5 Major Collector 6 Minor Collector 7 Local 63 Table 39 Link Functional Classification* Codes for HPMS based Counties Functional Class* Description 0 Rural Interstate 2 Rural Other Principal Arterial 3 Rural Minor Arterial 4 Rural Major Collector 5 Rural Minor Collector 6 Rural Local 7 Small Urban Interstate 8 Small Urban Freeway 9 Small Urban Other Principal Arterial 10 Small Urban Minor Arterial 11 Small Urban Major Collector 12 Small Urban Minor Collector 13 Small Urban Local 14 Urban Interstate 15 Urban Freeway 16 Urban Other Principal Arterial 17 Urban Minor Arterial 18 Urban Major Collector 20 Urban Local * " Virtual link" codes for each of the up to 21 HPMS Functional Class and Area Type combinations. 64 Table 40 TDM Network Link Emissions Data File Format Abbreviation Columns Format Type Description A Node 1  6 I6 A Node of link B Node 7  12 I6 B Node of link FC 13  15 I3 Functional Classification Code of Link ( see Table 43)

EMISS 17  19 A3 " VOC," or " CO," or " NOx"

ETYPE 21  31 A11 Emissions Sub Component Type ( see Table 44)

LDGV 32  41 F10.?* LDGV link emissions in grams LDGT1 42  51 F10.? LDGT1 link emissions in grams LDGT2 52  61 F10.? LDGT2 link emissions in grams LDGT3 62  71 F10.? LDGT3 link emissions in grams LDGT4 72  81 F10.? LDGT4 link emissions in grams HDGV2B 82  91 F10.? HDGV2B link emissions in grams HDGV3 92  101 F10.? HDGV3 link emissions in grams HDGV4 102  111 F10.? HDGV4 link emissions in grams HDGV5 112  121 F10.? HDGV5 link emissions in grams HDGV6 122  131 F10.? HDGV6 link emissions in grams HDGV7 132  141 F10.? HDGV7 link emissions in grams HDGV8A 142  151 F10.? HDGV8A link emissions in grams HDGV8B 152  161 F10.? HDGV8B link emissions in grams LDDV 162  171 F10.? LDDV link emissions in grams LDDT12 172  181 F10.? LDDT12 link emissions in grams HDDV2B 182  191 F10.? HDDV2B link emissions in grams HDDV3 192  201 F10.? HDDV3 link emissions in grams HDDV4 202  211 F10.? HDDV4 link emissions in grams HDDV5 212  221 F10.? HDDV5 link emissions in grams HDDV6 222  231 F10.? HDDV6 link emissions in grams HDDV7 232  241 F10.? HDDV7 link emissions in grams HDDV8A 242  251 F10.? HDDV8A link emissions in grams HDDV8B 252  261 F10.? HDDV8B link emissions in grams MC 262  271 F10.? MC link emissions in grams HDGB 272  281 F10.? HDGB link emissions in grams HDDBT 282  291 F10.? HDDBT link emissions in grams HDDBS 292  301 F10.? HDDBS link emissions in grams LDDT34 302  311 F10.? LDDT34 link emissions in grams * The F10? format is either F10.0, F10.1, F10.2, F10.3, or F10.4. The format selected for a field is based on the value of the field.

Table 41 San Antonio TDM Network Functional Classifications 65 Functional Class Code Functional Class Name 0 Local Roads 1 Radial Freeway 2 Radial Parkway 3 Expressway 4 Primary Arterial Divided 5 Primary Arterial Undivided 6 Minor Arterial Divided 7 Minor Arterial Undivided 8 Collectors Divided 9 Collectors Undivided 10 Frontage Road 11 Ramp 12 Circumferential Freeway 13 Circumferential Parkway 14 Circumferential Arterial 35 HOV*

40 Intrazonal * Only used 2015 network but classified as Radial Freeway due to lack of data for HOV. 66 Table 42 Emissions* Sub component Type Sub Component Abbreviation Description Composite Total emissions Exh Running Exhaust running emissions Start Start emissions Hot Soak Hot Soak VOC emissions Diurnal Diurnal VOC emissions Rest Loss Resting loss VOC emissions Run Loss Running loss VOC emissions Crankcase Crankcase VOC emissions Refueling Refueling loss VOC emissions * VOC, CO, and NOx. 68 APPENDIX B EMISSIONS ESTIMATION PROGRAMS 70 TTI EMISSIONS ESTIMATION PROGRAMS The following is a summary of programs developed by TTI that may be used to produce TDM network link based and HPMS " virtual link" based, hourly, on road mobile source emissions estimates for air quality analyses.

For the TDM based analyses the emissions estimates are made at the TDM network link level ( for thousands of links) where geographical coordinates are associated.

For the HPMS based analyses, emissions estimates are made at the functional classification/ area type level which constitutes a 21 cell array defined by seven functional classifications and three area types, or road type " cells." These road type cells may be viewed as a roadway network ( analogous to the TDM network, but with larger and fewer links) consisting of up to 21 links ( or, with directionality included, 42 links).

Hereafter, for the purpose of this discussion, the term " link" may be used to mean either a TDM network link or an HPMS " virtual link."

The main emissions estimation programs are: PREPIN ( 2BW for TDM network analyses and 254HPMS for HPMS analyses), POLFAC62, RATEADJ62, RATEADJV62, IMPSUM62, and SUMALL62. PREPIN prepares activity input, POLFAC62 prepares emissions factor input, the RATEADJ programs make special adjustments to emissions factors when required, IMPSUM62 calculates emissions by time period, and SUMALL62 summarizes emissions and other EI data at various levels by 24 hour period.

PREPIN The PREPIN2BW program post processes travel model output to produce time of day specific, on road vehicle fleet, link VMT and speed estimates for emissions inventory applications. The PREPIN2BW program was developed for use in urban areas that do not have all of the time of day assignments and operational speeds available as may be required for air quality analyses of particular temporal scales ( e. g., hourly).

For example, PREPIN2BW reads a travel demand model traffic assignment data set from a directional four period time of day assignment ( another common assignment read by PREPIN2BW is the nondirectional or directional 24 hour assignment). PREPIN2BW initially scales the assignment volumes on each link to the appropriate VMT ( seasonal, day of week specific, for instance). Time of day ( hourly, for example) factors ( and directional split factors, in the case of a nondirectional assignment) are applied to the adjusted assignment results on each link to estimate the directional time of day travel on the link. Speed models, originally developed for the Dallas/ Fort Worth Region or optionally the Houston/ Galveston Region, are used to estimate the operational time ofday speeds by direction on the links. Special intrazonal links are defined ( as intrazonal links are not a feature of travel demand models), and the VMT and speeds for intrazonal trips are estimated. These VMT and speeds by link are subsequently input to the IMPSUM6 program for the application of MOBILE6 emissions factors.

PREPIN254HPMS The PREPIN254HPMS program processes the Statewide HPMS county AADT VMT, centerline miles, and lane miles by functional classification and area type to produce hourly, on road vehicle fleet, seasonal and day of weekspecific actual or forecast VMT and directional speed estimates for EI applications. These estimated VMT and speeds are produced for 21 HPMS functional classification/ area type combinations, or " links." The program was developed for use in areas that do not have TDM networks, and for EI applications where network link based detail is not required. However, the HPMS link speeds are developed analogous to those produced from network travel model based input data, except with a much smaller set of " links." The main inputs are:

· TxDOT statewide HPMS data set at the county level which includes AADT VMT, centerline miles, and lane miles by HPMS area type and functional class;

· county level VMT control totals; 71 · list of Texas county names;

· hourly VMT distributions; and · Dallas/ Fort Worth speed modeling inputs to include volume/ delay equation parameters adapted for HPMS, and freeflow speeds and lane capacities by HPMS functional classification and area type.

The program initially allocates the county control total VMT ( VMT adjusted for season, etc.) to the link, proportional HPMS AADT VMT on each link. Hourly factors and directional split factors are applied to the adjusted VMT on each link to estimate the hourly directional VMT ( and volumes) by HPMS link. Speed models, originally developed for the Dallas/ Fort Worth Region, are used to estimate the hourly operational speeds by direction for each link. The operational speeds are based on v/ c derived directional delay ( minutes/ mile) applied to the estimated freeflow speeds for each link. These HPMS link VMT and speed estimates are subsequently input to the IMPSUM62 program for the application of MOBILE6 emissions factors.