TECHNICAL NOTE Transportation Air Quality Technical Support Interagency Contract with Texas Natural Resource Conservation Commission

Transcription

1 TECHNICAL NOTE Transportation Air Quality Technical Support Interagency Contract with Texas Natural Resource Conservation Commission TO: FROM: Mary McGarry-Barber, Project Manager Texas Natural Resource Conservation Commission Dennis G. Perkinson, Ph.D., and Martin E. Boardman Texas Transportation Institute DATE: 31August2002 SUBJECT: Rate-of-Progress On-Road Mobile Source Emissions Inventories for the Houston Galveston Ozone Nonattainment Area: 1990 Base Year, 2005 Milestone Year, and 2007 Attainment Year (Umbrella Contract : Task 2) - Revised Final INTRODUCTION In January of 2002, U.S. Environmental Protection Agency (EPA) released the newest version of the on-road mobile source emission factor model, MOBILE6. As part of the Houston-Galveston Ozone Nonattainment Area (HGA) State hnplementation Plan (SIP), the Texas Natural Resource Conservation Commission (TNRCC) agreed to update the SIP within two years after official release of MOBILE6. The update must include revised inventories, including on-road mobile inventories developed using MOBILE6. A part of the HGA SIP is the Rate-of-Progress (ROP) demonstration. To update the ROP portion of HGA SIP to be consistent with MOBILE6, updated ROP inventories, developed using MOBILE6, are required. The eight HGA counties are: Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery, and Waller. This Technical Note documents the methods the Texas Transportation Institute (TTI) used to develop the HGA ROP MOBILE6-based on-road mobile source emissions inventories for 1990, 2005, and There are seven county level emissions inventories required: the 1990 base year emissions inventory (BYEI), the 1990 adjusted base year emissions inventory (ABYEI) relative to 2005, the 2005 pre-90 control emissions inventory (Pre-90CEI), the 2005 control strategy emissions inventory (CSEI), the 1990 ABYEI relative to 2007, the 2007 Pre-90CEI, and the 2007 CSEI. These on-road mobile source inventories may be used in aggregate with the corresponding ROP emissions estimates from the other major source categories (point, area, and non-road mobile) to calculate target year (i.e., milestone and attainment year) ROP required emissions 1

2 reductions, emissions target levels, and to estimate control strategy performance in relation to these target levels. The results of this analysis may also be used to develop Motor Vehicle Emissions Budgets (MVEB) for transportation conformity determinations. The emissions estimates are for typical HGA ozone season (July through September) weekday (average Monday through Friday) travel. The regional temperature and humidity input data are averages from the 10 highest ozone exceedance days from 1997 through Emissions of volatile organic compounds (VOC), carbon monoxide (CO), and oxides of nitrogen (NOx) are estimated for each county on an hourly basis. The hourly estimates are computed by network links (characterized by 13 facility types, including special intrazonal links), and are categorized by 28 vehicle types. The hourly emissions are summarized as ozone season weekday totals. The overall emissions inventory methodology (i.e., travel demand model link-based time-ofday) has not changed. However, there are differences in some procedures that are introduced to the emissions inventory process with the use of the MOBILE6 model (e.g., 28 vehicle classification categories, as opposed to the previous eight-category scheme). Documented within are emissions inventory summaries and descriptions with corresponding lists of controls modeled. Also included are methods relating to calculating inventory elements including link-based vehicle miles traveled (VMT) estimates from Houston-Galveston Area Council's (HGAC) travel demand models (TDM), seasonal weekday adjustments and Highway Performance Monitoring System (HPMS) consistency adjustments to VMT, speeds, VMT mix, MOBILE6 emissions factors, and emissions. ACKNOWLEDGMENTS Mary McGarry-Barber and Chris Kite, both with the TNRCC, and Martin Boardman and L.D. White, both 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. The HGAC provided the HGA network traffic assignments, intrazonal trips, and zonal radii. Dennis Perkinson, Ph.D., of TTI, developed seasonal weekday VMT control totals, VMT adjustment factors for season and HPMS consistency, and VMT mix. Charles Bell, also of TTI, and White processed the VMT and modeled operational speeds. White performed the emissions estimations. Each member of the assigned TTI staff contributed to the quality assurance of the emissions inventory elements. Dr. Perkinson was the principle investigator for this project. This work was performed by TTI under contract to TNRCC. Mary McGarry-Barber was the TNRCC 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 617 /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 or other electronic media is used to record 2

3 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 TNRCC staff. The emissions inventory data sets were provided to the TNRCC Technical Analysis Division on CD-ROM. Appendix A lists the data set file names and descriptions contained on each CD ROM. EMISSIONS INVENTORY SUMMARIES A summary of ozone season weekday emissions and VMT and speeds for each of the seven ROP emissions inventory estimates is presented in Table 1. The detailed emissions inventory summaries (including emissions estimates cross classified by vehicle and road type by county) were provided on CD-ROM (see descriptions in Appendix A). Table 1 HGA All Counties 1990, 2005, and 2007 ROP Ozone Season Weekday On-Road Mobile Source VMT, Average Speed (mph), and Emissions (tons per day) Emissions Inventory VMT Speed voe co NOx 1990 BYEI 98,710, , ABYEI Relative to ,710, , Pre-90CEI 129,149, , CSEI 129,149, , ABYEI Relative to ,710, , Pre-90CEI 135,093, , CSEI 135,093, , Three activity data sets and and five emissions factor data sets were used to develop these seven emissions inventories. Table 2 summarizes the activity and emissions factor elements as applied to produce each of the inventories. 3

4 Table2 1990, 2005 and 2007 Rate-of-Progress Emissions Inventories, Activity, and Emissions Factors Activity* Emissions Inventory Emissions Factors 1990 Base Year: 1990BYEI 1990 (1990 vehicle fleet and controls) 1990 ABYEI Relative to Pre-90 Control: 2005 Pre-90CEI (2005 vehicle fleet, 1990 controls**) Control Strategy: 2005 CSEI (2005 vehicle fleet and controls) ABYEI Relative to Pre-90 Control: 2007 Pre-90CEI (2007 vehicle fleet, 1990 controls**) Control Strategy: 2007 CSEI (2007 vehicle fleet and controls) * VMT, Speeds, VMT mix. **These emissions factors are modeled as the actual 1990 base year emissions factors except for: 1) calendar year of evaluation is for the future year, 2) "no clean air act" command is applied, 3) RVP is summer 1992 RVP limit, and 4) user-input diesel fractions correspond to the MOBILE6 calendar year input. The ROP planning process includes calculating the emissions baseline (ABYEI) from which the ROP required percent emissions reductions are calculated. As specified by the 1990 Clean Air Act Amendments (CAAA), certain on-road mobile source emissions reductions are not creditable toward these required percentage reductions. The non-creditables include the emissions reductions that would occur by the target years (in this task, 2005 and 2007) due to the pre-1990 CAAA Federal Motor Vehicle Control Program (FMVCP) and promulgated Federal fuel volatility regulations (summertime gasoline Reid Vapor Pressure [RVP] limits beginning in 1992). For this analysis, the pre-1990 CAAA FMVCP and 1992 summertime RVP limit are termed pre-90 controls. The estimated noncreditable emissions reductions due to pre-90 controls are calculated by subtracting the 1990 ABYEI relative to the target year, from the actual 1990 BYEI. The difference between these two inventories is in the emissions factors. For example, Table 2 shows that the 1990 B YEI is the product of the 1990 vehicle fleet and controls emissions factors and 1990 activity. The 1990 ABYEI relative to 2005 is also calculated with the 1990 BYEI activity, however, uses the emissions factors for a 2005 fleet with pre-90 controls. The 1990 BYEI minus the 1990 ABYEI relative to 2005 thus equals the noncreditable "pre-90 control" emissions reductions, or those reductions resulting from pre-90 FMVCP (fleet turnover between 1990 and 2005) and summertime 1992 RVP limit. 4

5 The future year on-road mobile source emissions inventories with growth (estimated future year VMT) are the Pre-90CEI (in previous ROP analyses termed the current control emissions inventory, or CCEI), and the CSEI. The Pre-90CEI is future year VMT applied to future year fleet emissions factors with pre-90 controls (i.e., future year emissions levels for a fleet under the pre-90 control scenario). (For comparison, note in Table 2 that the 1990 ABYEI relative to 2005 and the 2005 Pre-90CEI, the second and third Els, are the same except for the activity element.) The CSEI is the product of future year VMT and emissions factors under the post-caaa control scenario. For each future evaluation year, the Pre-90CEI minus the CSEI yields the estimated emissions reductions resulting from the modeled post-caaa controls scenario. The control programs, as modeled in the emissions factors, are summarized in Table 3. Table 3 Emissions Factor Modeled Control Programs For 1990, 2005, and 2007 ROP Emissions Inventories Emissions Factor Analysis Controls Modeled Pre-90 FMVCP, 1990 Base Year 1990 State program (Anti-Tampering Program [ATP], Harris County), (estimated actual RVP applied). Pre-90 FMVCP, 2005 Pre-90 Control* Federal 1992 Summertime RVP limit, 1990 State programs (ATP, Harris County). Pre-90 FMVCP, 2005 Control Post-1990 FMVCP, Strategy Summer Reformulated Gasoline, 2005 State programs (I/M, ATP, LED; all HGA). Pre-90 FMVCP, 2007 Pre-90 Control* Federal 1992 Summertime RVP limit, 1990 State programs (ATP, Harris County). Pre-90 FMVCP, 2007 Control Post-1990 FMVCP, Strategy Summer Reformulated Gasoline, 2007 State programs (I/M, ATP, LED; all HGA). *Applied in both the 1990 adjusted base year emissions inventories, and the future case Pre-90 Control emissions inventories. 5

6 OVERVIEW OF METHODOLOGY To develop the HGA ozone ozone season weekday emissions estimates, a directional link-based, time-of-day methodology was applied. Emissions estimates were calculated at the roadway network link level for each hour of the typical ozone season weekday. The MOBILE6 model was used to develop hourly emissions factors by MOBILE6 road type (drive cycle) and 28 vehicle types. Only the speed sensitive freeway and arterial emissions factors were applied - freeway emissions factors to freeway links, and arterial emissions factors to nonfreeway links. The activity basis were the Houston-Galveston TDM link-based Average Non-Summer Weekday Traffic (ANSWT) VMT and intrazonal trips from 1993, 2005, and 2007 network assignments and trip matrices. VMT estimates from the 1993 travel model data set were adjusted to 1990 base year ozone season weekday control totals. The 2005 and 2007 travel model VMT estimates were adjusted for the ozone season weekday and for consistency with HPMS. Automatic traffic recorder (ATR) data were used to produce the ozone season (July through September) weekday (Monday through Friday) VMT adjustments. Hourly travel fractions were applied to allocate the VMT by hour-of-day. Based on the estimated hourly traffic link volumes and capacities, hourly operational speeds were modeled by link with the Houston speed model. Vehicle classification data were used to estimate the four time-of-day period VMT mixes for apportioning fleetwide link-vmt to the 28 EPA vehicle types. Link-level emissions by vehicle type were calculated by hour. Hourly link-emissions estimates for each county are summed by road type and vehicle type for the typical ozone season weekday. TTI previously developed a series of computer programs to produce detailed on-road mobile source emissions inventories. These computer programs were used to produce and apply the major emissions inventory elements (adjusted operational time-of-day link VMT by vehicle type, operational link-speeds, and MOBILE6 emissions factors) to calculate the emissions estimates. Appendix B describes these programs and their application. ESTIMATION OF VMT The outputs of the VMT estimation process are HPMS-consistent estimates of county-level, ozone season weekday, 1990, 2005, and 2007 VMT (and speeds, as discussed in a following section) by hour and direction, for each link of the Houston-Galveston Travel Demand Model (TDM) networks and the added intrazonal links. The PREPIN2 program (for post-processing TDM data for air quality analyses, see Appendix B) was applied to produce the adjusted link-based VMT estimates. This program produced 24 hourly link files for each evaluation year containing the county and road type-indexed ozone season weekday link-data (estimated operational VMT and speeds). 6

7 Data Sources The latest HGA 2005 and 2007, directional, four time-of-day period, equilibrium traffic assigned networks and intrazonal trips and zonal radii (assumed intrazonal trip length) were provided by HGAC (August, 2002). These TDM data, which cover the HGA eight-county area, were used as the basis for developing the link-based 2005 and 2007 ozone season weekday VMT estimates. 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 activity basis for the original (MOBILES-based) ROP 1990 base year emissions estimates were HGAC 1990 mainframe TDM data. This 1990 TDM data set no longer exists. TTI used PREPIN2 results (i.e., hourly operational link data output files with inputs listing) from the HGAC 1993 TDM network as the basis to re-produce the 1990 operational link-vmt and speeds. The original 1990 ROP base-year county VMT totals (HGAC, 1993) were used as the control totals. To adjust and allocate the Houston-Galveston TDM VMT as needed, several other sources of data were required. HPMS VMT estimates are based on traffic count data collected according to a statistical sampling procedure specified by the Federal Highway Administration (FHW A) designed to estimate VMT. A wide range of traffic data is collected under the HPMS program. For the purpose of this study, county total HPMS Annual Average Daily Traffic (AADT) VMT were used to ensure the 2005 and 2007 travel model VMT were consistent with the HPMS VMT estimates. (EPA and FHW A have endorsed HPMS as the appropriate source of VMT and require that VMT used to construct on-road mobile source emissions inventories be consistent with that reported through HPMS.) ATR vehicle counts are collected by the Texas Department of Transportation (TxDOT) at selected locations on a continuous basis throughout Texas. These counts are available by season, month, and weekday, as well as on an annual average daily basis (i.e., AADT). Since they are continuous, they are especially well suited for making seasonal, day-of-week comparisons (i.e., adjustment factors), even though there may be relatively few ATR data collection locations in any given area. Data from the ATR stations in the HGA were grouped for this analysis. These ATR count data were used to produce the ozone season weekday adjustment factors. HGA time-of-day factors from a previous HGA emissions inventory analysis were applied to estimate the hourly travel fractions for the 2005 and 2007 analyses, as well as for (TXDOT vehicle classification count data were used to develop the VMT mix, or VMT fractions, for the 28 EPA vehicle types, discussed in a later section.) VMT Adjustments There were two procedures used to make the required VMT adjustments (i.e. for season and for HPMS consistency) to the TDM link VMT, one procedure for 1990, and the other for 2005 and For the 1990 base year VMT, the original 1990 ROP SIP base year county VMT totals (HPMS Adjustment for All On-Road Mobile Source Emissions for the Houston-Galveston Ozone Nonattainment Area, HGAC, August 1993) were applied as the control totals. For the 7

8 2005 and 2007 future year VMT, the HPMS adjustment factor and ozone season weekday adjustment factor were applied Base Year VMT Adjustment As the original 1990 base year analysis adjusted link VMT and speeds were not available, they were reproduced from a 1993 TDM data set. The 1993 TDM network 24-hour nondirectional assignment VMT and intrazonal VMT were back-calculated from a 1993 TDM network-based PREPIN link VMT and speeds data set. These back-calculated 1993 TDM network data were used as the basis for developing the link-based 1990 ozone season weekday VMT estimates. With the back-calculated volumes, input speeds, link distance, input factor sets, and the original 1990 ROP base-year VMT for control totals, PREPIN2 (see program descriptions, Appendix B) was re-run to reproduce the required 1990 base year link VMT and speeds. To adjust the estimated 1993 travel model VMT to the original fully adjusted (i.e., for the peak ozone season, and consistency with the 1990 HPMS VMT data) 1990 ROP SIP VMT, the original ROP SIP 1990 base year VMT were used as the control totals (see Table 4). For each county, the 1993 assignment VMT total was divided into the 1990 base year control total to produce county-level VMT adjustment factors. These VMT adjustment factors were then multiplied by the 1993 county-level link VMT to produce the 1990 link-level ozone season weekday VMT estimates. Table4 HGAC ROP 1990 Ozone Season Weekday VMT Control Totals County VMT Brazoria 4,565,964 Chambers 1,615,624 Fort Bend 4,462,693 Galveston 5,165,706 Harris 75,360,458 Liberty 1,639,720 Montgomery 4,860,970 Waller 1,039,331 HGAC 98,710,466 Source: "HPMS Adjustment for All On-Road Mobile Source Emissions for the Houston-Galveston Ozone Nonattainment Area," Houston-Galveston Area Council, August

9 2005 and 2007 Future Year VMT Adjustment The unadjusted travel model VMT and ozone season weekday VMT, as adjusted for this analysis, are summarized for 2005 and 2007 in Tables 5 and 6, respectively. These travel model VMT were adjusted for consistency with HPMS, and to ozone season weekday-specific travel. The HPMS adjustment factor was developed using the VMT from the 1995 travel model validation and the 1995 county HPMS VMT reported by TxDOT. The formula for the HPMS factor calculation is: HPMS VMT (AADT) x Non-Summer Weekday Adjustment Factor= HPMS VMT (ANSWT) HPMS VMT (ANSWT) I Model VMT (ANSWT) = HPMS Factor ANSWT is the VMT produced by the travel model. HPMS AADT VMT is from the HPMS for 1995 for the eight HGAC counties. The seasonal adjustment (i.e., AADT to ANSWT) is based on 1995 ATR data from the Houston area as defined by the Houston TxDOT District. For the HPMS adjustment factor, the actual values are: 97,926,113 x = 103,924, ,924,087.4 I 106,829,526.1= A similar procedure is used to calculate the ozone season weekday adjustment factor. Aggregated ATR data (for July through September, 1999 and 2000) from the HGA ATR stations were used. The eight-county area ozone season weekday factor was produced by dividing the average Monday through Friday count by the ANSWT count. The seasonal adjustment factor is

10 Tables HGA 2005 Travel Model and Adjusted VMT (Rounded to Whole Numbers) County Travel Model VMT* Ozone Season Weekday VMT Brazoria Chambers Fort Bend Galveston Harris Liberty 5,595,074 5,574,133 2,861,513 2,850,804 8,297,339 8,266,283 5,092,889 5,073,826 94,019,602 93,667,716 2,245,145 2,236,743 Montgomery 9,955,953 9,918,692 Waller 1,567,354 1,561,488 HGA 129,634, ,149,683 * VMT totals from time-of-day traffic assignments including intrazonal VMT. 10

11 Table 6 HGA 2007 Travel Model and Adjusted VMT (Rounded to Whole Numbers) County Travel Model VMT* Ozone Season Weekday VMT Brazoria Chambers Fort Bend Galveston Harris Liberty 6,200,756 6,177,548 2,920,372 2,909,442 9,196,225 9,161,805 5,295,881 5,276,058 97,091,378 96,727,996 2,369,959 2,361,086 Montgomery 10,728,440 10,688,288 Waller 1,797,891 1,791,161 HGA 135,600, ,093,385 * VMT totals from time-of-day traffic assignments including intrazonal VMT. Hourly Travel Factors Hourly weekday volume factors were needed to allocate the adjusted 1990 single 24-hour assignment and 2005 and 2007 four-time-of-day period assignment volumes to each hour of the day. To allocate 1990 base year VMT by hour, the hourly weekday volume factors developed for single 24-hour assignments as applied in previous HGA SIP analyses (Gridded Mobile Source Emissions Estimates for the Houston-Galveston Nonattainment Counties to Support The Attainment Demonstration SIP, TTI, December 2000) were used. These single assignment hourly volume factors were processed for use with the four time-of-day period assignments and used to allocate the 2005 and 2007 adjusted VMT by hour of day as well. The single assignment hourly volume factors are a set of factors by 24 time periods, five HGAC TDM area types, and the13 HGAC TDM network functional classes. The VMT factors may be grouped by four area types (by combining Central Business District and Urban area types (Table 7) and by three functional groups (Table 8). The hourly weekday volume factors developed for single 24-hour assignments (shown in Appendix C), were applied to the adjusted 24-hour 1990 link and intrazonal VMT by functional group and area type to allocated the 1990 link VMT by hour-of-day. 11

12 Table 7 HGAC Network Area Types 1. Central Business District (CBD) 2. Urban 3. Urban Fringe 4. Suburban 5. Rural Table 8 HGAC Functional Classification to Functional Group Table of Equals for Application of Hourly VMT Factors Functional Group 1. Freeways, Interstates Network Functional Classifications 1. Urban Interstate Freeways 2. Urban Other Freeways 10. Rural Interstate Freeways 11. Rural Other Freeways 5. Urban Principal Arterials 6. Urban Other Arterials 2. Arterials, Major Collectors 12. Rural Principal Arterials 13. Rural Other Arterials 14. Rural Major Collectors 3. Collectors, Locals 7. Urban Collectors 8. Locals (Centroid Connectors) 15. Rural Collectors 16. Locals (Intrazonals) Table 9 shows the traffic assignment time-of-day travel periods for the 2005 and 2007 four time-of-day -period network traffic assignment provided by HGAC. 12

13 Table9 HGAC Time-of-Day Travel Periods Period Hours AM Peak Midday PM Peak Overnight 6:00 a.m. - 9:00 a.m. 9:00 a.m. - 3:00 p.m. 3:00 p.m. - 7:00 p.m. 7:00 p.m. - 6:00 a.m. To produce the hourly volume fractions for allocating the four-period assignment and intrazonal VMT to the hours of day, the single assignment hourly travel factors by area type and functional group were grouped within their corresponding four time-of-day periods. The factors were then normalized within each period. The resulting weekday hourly volume factors are summarized in Appendix C. These hourly volume factors were applied to the adjusted four timeof-day period link and intrazonal VMT by functional group and area type to allocate the VMT to each hour of the day. The VMT summaries by eight-county area, county, day, hour, road type, and vehicle type are included with the emissions inventory data provided to TNRCC on CD-ROM. Appendix A lists the electronic data files with descriptions that were provided to TNRCC. ESTIMATION OF LINK SPEEDS The operational speeds by direction and hour were calculated on each freeway, arterial, and collector link using the Houston Speed Model. Operational speeds estimated for 1990, 2005, and 2007 were based on two speed limit scenarios: 1) for 1990, operational speed estimates are affected by the actual 1990 speed limits (i.e., 55 mph maximum), and 2) for 2005 and 2007, operational speed estimates are affected by the speed limits in effect in early 2002 (i.e., 70 mph maximum) prior to implementation of the current 55 mph HGA maximum speed limit. (With the expectation that the current HGA 55 mph maximum speed limit will be lifted to the previous higher speed limits, TNRCC chose to model emissions under the previous higher speed limit senario.) The Houston Speed Model requires a freeflow speed factor, a Level of Service (LOS) E speed factor and "speed reduction factor" (SFR) for each link. No speed model was used to estimate speeds for locals streets (that includes centroid connector and intrazonal functional classifications). Additional details of these speed modeling methods are documented in the TTI Research Report , "Texas Mobile Source Emissions Software, Version 2.0: User's Guide," February (Documentation of the most recent software versions are currently in review draft form.) 13

14 The Houston speed model calculates the operational link speeds by direction and time period as a function of the link's estimated freeflow speed, estimated LOS E speed, and volume-tocapacity (V/C) ratio-based SRFs. The SRFs describe the decay from a freeflow speed (i.e., the uncongested speed for a V/C ratio approaching 0.0) to an LOSE speed (i.e., the congested speed for a V/C ratio of 1.0). The values of the SRFs vary from 0.0 to 1.0. The speed factors required to estimate the operational link speeds are grouped by functional classification group (see Table 10) and area type (see Table 7). The capacity factors used for the 1990 base year analysis are also grouped according to this scheme. The capacity factors applied in the 2005 and 2007 analyses are simply grouped by the four time-of-day assignment periods (see Table 9) with no variation by functional class or area type. The capacity factors are applied to the network assignment (24-hour and four period time-of-day) link capacities to allocate the network capacities by hour of day. Table 10 Functional Classification to Functional Group Table of Equals for Application of Capacity and Speed Factors Functional Group 1. Freeways, Interstates 2. Principal Arterials 3. Other Arterials, Major Collectors 4. Collectors 5. Locals Corresponding Network Functional Classifications 1. Urban Interstate Freeways 2. Urban Other Freeways 10. Rural Interstate Freeways 11. Rural Other Freeways 5. Urban Principal Arterials 12. Rural Principal Arterials 6. Urban Other Arterials 13. Rural Other Arterials 14. Rural Major Collectors 7. Urban Collectors 15. Rural Collectors 8. Locals (Centroid Connectors) 16. Locals (Intrazonals) 14

15 Since the 1990 base year VMT are based on a nondirectional assignment, directional split factors were applied to volumes at the link level to produce the directional volumes. The directional splits for 1990 range from 48/52 to 76/24 depending on the hour of day and area type and functional classification combination. Directional volumes are already included in the HGAC 2005 and 2007 network time-of-day directional assignments. The V/C ratios by time period (hour) were required for each link. Directional time period link volumes were calculated by multiplying the associated directional link-vmt 1 by the time period volume factor divided by the link distance. The directional time period link capacities were calculated by multiplying the time period directional link capacity (for 1990, a directional split of was assumed for capacity) by the time period capacity factor (see Appendix D). The hourly capacity factors from each of the four time-of-day periods are calculated as the inverse of the hours within the time period. The capacity factors for each time period are the same for each area type and functional class. The time period link V/C ratios were then calculated by dividing the directional link volume by the directional link capacity. To estimate the link freeflow and LOS E speeds, the link data input speeds (i.e., not the operational speeds, but the speeds used by the travel model to produce correct link volumes), indexed by functional group and area type, were multiplied by the pair of speed factors corresponding to each functional group and area type. These two sets of speed factors were developed by dividing the distance-weighted average link input speeds into the average modeled freeflow speeds (V/C = 0.0), and the average modeled LOSE speeds (V/C = 1.0), respectively. The average freeflow and LOS E speeds are affected by the coded link-speed limits. For the 1990 base year evaluation, the network speed limits modeled were for a maximum of 55 mph. For the 2005 and 2007 analyses, the operational speed modeling is based on maximum speed limits of 70 mph. The estimated link freeflow and LOS E speeds were assumed the same in each direction. The calculated freeflow and LOS E speed factors input to the Houston speed model corresponding to the two maximum speed limit scenarios are shown in Appendix D. The speed model (for V/C ratios from 0.00 to 1.00) is expressed as: Where: Svic = estimated directional speed for the forecast V/C ratio on the link in the subject direction, So.o = Si.o = SRFv1c = estimated freeflow speed for V /C ratio equal to 0.0, estimated LOS E speed for V /C ratio equal to 1.0, and speed reduction factor for the V /C ratio on the link. The V /C ratio can be 0.0 to 1.0. See four SRF plots in Appendix D. 1 From one of the four time-of-day directional assignments used. 15

16 For V/C ratios greater than 1.0, the model extension discussed below is used. The speed extension model used for V/C > 1.0 is: Sv 1 c = S1.o x (1.15/(1.0 + (0.15 x (V.C) 4 ))) Where: Svic S1.o = estimated directional speed for the forecast V/C ratio on the link in the subject direction, = estimated LOSE speed for the V/C ratio equal to 1.0, and V/C = the forecast V/C ratio on the link. The V/C ratio can be 1.0 to 1.5. For V/C ratios greater than 1.5, the speed is computed for the V/C ratio of 1.5. These models were applied, dependent on the link V /C ratio, to estimate the speeds at the link level for freeways, arterials, and collectors. Capacity data are not used, however, for the centroid connector and intrazonal functional classifications that comprise the Locals road type. The centroid connector traffic assignment input speeds were thus 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 were provided electronically to TNRCC (see Appendix A for electronic data descriptions). ESTIMATION OF VMT MIX VMT mix was estimated using TxDOT weekday vehicle classification data for As was the case with the seasonal adjustment factor for the VMT estimation procedure, these data were aggregated to the HGA region (i.e., all eight HGAC counties). TxDOT classification counts classify vehicles into the standard FHW A vehicle classifications (which are based on vehicle length/number of axles) using best practice vehicle classification count methods. C P B SU2 SU3 SU4 SE4 SES SE6 SD5 Passenger vehicles Two-axle, four-tire single-unit trucks Buses Six-tire, two-axle single-unit vehicles Three-axle single-unit vehicles Four or more axle single-unit vehicles Three or four axle single-trailer vehicles Five-axle single-trailer vehicles Six or more axle single-trailer vehicles Five or less axle multi-trailer vehicles 16

17 SD6 SD7 Six-axle multi-trailer vehicles Seven or more axle multi-trailer vehicles EPA and MOBILE use a different vehicle classification scheme than the FHW A categories. There are 28 vehicle categories defined as a function of gross vehicle weight rating (GVWR) and fuel type (see table 10). The FHW A axle/vehicle length-based classification categories must be converted into 28 MOBILE GVWR/fuel type-based categories. 17

18 Table 11 EPA MOBILE6 Vehicle Types Category Description GVWR LDGV Light duty gasoline vehicle ::; 6,000 LDGTl 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 HD DBS Heavy duty diesel school bus all HDDBT Heavy duty diesel transit bus all MC Motorcycle all 18

19 The FHW A category counts (based on number of axles or vehicle length) are first converted into eight EPA categories (based on GVWR). Vehicle classification counts are first aggregated into two intermediate groups. Passenger Vehicles Heavy-Duty Vehicles C + P SU2 + SU3 + SU4 + SE4 +SES+ 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 county registration data. LDV LDT x PV (Harris County 2000 registration data shown) x PV (Harris County 2000 registration data shown) A third intermediate allocation further separates light-duty trucks into LDTl and LDGT2. (Note that LDTl is itself intermediate and is further divided into LDGTl and LDDT.) LDTl LDGT x LDT (Harris County 2000 registration data shown) x LDT (Harris County 2000 registration data shown) Next, the remaining FHW A categories and this intermediate group are disaggregated into the eight EPA vehicle groups, as shown. Note that TxDOT vehicle classification count procedures do not distinguish between gasoline and diesel light-duty trucks, consequently, MOBILE defaults for the year of interest are used. As before, actual Texas county 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 LDDV LDGTl LDDT LDGT2 HDGV HDDV MC x LDV (MOBILE6 default for 2000 shown) x LDV (MOBILE6 default for 2000 shown) x LDTl (MOBILE6 default for 2000 shown) x LDTl (MOBILE6 default for 2000 shown) x LDT (Harris County 2000 registration data shown, as above) x HDV (Harris County 2000 registration data shown) x HDV (Harris County 2000 registration data shown) of total (subtracted from LDGV) This converts the FHW A axle count-based categories into GVWR categories. This part of the conversion procedure can be summarized schematically, starting with the TxDOT vehicle classification data. These datea themselves provide sufficient information to complete the first step in the conversion process, the allocation of vehicles into passenger vehicles (PV) and heavy duty vehicles (HDV). Steps 2 and 3 further allocate these categories using county 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 12). 19

20 Table 12 Initial Vehicle Classification Conversion Procedure Start Step 1 Step2 Step3 Step4 LDV LDGV MC LDGV Total Vehicles PV LDT LDTl LDDV LDGTl LDDT LDGT2 HDV HDGV HDDV MOBILE6 requires 28 vehicle classification categories (as opposed to the eight in MOBILES). The 28-category typology is a subset of the eight category typology. A combination of EPA MOBILE6 defaults and Texas vehicle registration data are used to expand the basic EPA eight-category model. Thus, the procedures employed to expand the EPA eight-category scheme to the 28-category scheme are largely incremental extensions of the eight-category procedure, involving the disaggregation of the HDGV, LDGT, HDDV, and LDDT categories and the addition of three bus categories. For the 28-category EPA scheme, heavy-duty vehicles (HDGV and HDDV) are separated into eight categories each. These 16 categories are separated from total heavy-duty vehicle (HDV) counts that have been separated by fuel type using county registration data. Each HDV category (HDGV and HDDV) is then divided into sub-categories based on regionally grouped TxDOT county vehicle registration data. The 28-category EPA scheme further divides the two light-duty truck categories based in part on assumed loading. The previous LDGTl 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. Adjusted loaded vehicle weight is the average of vehicle curb weight and GVWR. Thus, two new intermediate categories are introduced. These are light lightduty 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. 20

21 These two new intermediate categories are then used to define the four light-duty truck categories using EPA MOBILE6 defaults for the year of interest. The four LDT categories are: LDGTl - Light light-duty trucks through 3,750 pounds loaded vehicle weight; LDGT2 - Light light-duty trucks greater than 3,750 pounds loaded vehicle weight; LDGT3 - Heavy light-duty trucks to 5,750 pounds adjusted loaded vehicle weight; and LDGT4 - Heavy light-duty trucks greater than 5,750 pounds adjusted loaded vehicle weight. 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., 2005 and 2007). For historical VMT mix estimates, the MOBILE6 default values consistent with the historical year are used (i.e., 1990). No other adjustments are made to alter the count data and conversion procedure to accommodate future years or historical years. Table 13 shows the VMT mix estimation procedure summary. Tables 14 through 16 show the Weekday VMT mixes developed for 1990, 2005, and 2007, respectively. 21

22 Table 13 VMT Mix Estimation Procedure Summary EPA-8 EPA-28 Conversion LDGV LDGV.9977 * LDV LDGTl LDGTl.2310 * LLDT LDGT * LLDT LDGT2 LDGT * HDLT LDGT * HDLT HDGV2b.513 *HDGV HDGV3.193 * HDGV HDGV4.089 *HDGV HDGV5.038 *HDGV HDGV HDGV6.092 *HDGV HDGV7.037 *HDGV HDGV8a.034*HDGV HDGV8b.004*HDGV HDGB.2045 * B LDDV LDDV.0023 * LDV LDDT LDDT * LDDT LDDT * LDDT HDDV2b.253 * HDDV HDDV3.132 * HDDV HDDV4.077 *HDDV HDDV5.050 *HDDV HDDV HDDV6.159 * HDDV HDDV7.105*HDDV HDDV8a.178 * HDDV HDDV8b.046*HDDV HDDBT.3253 * B HD DBS.4702 * B MC MC MC 22

23 Intermediate category factors and sources: Notes to Procedure Summary LDV LDT LDTl HLDT LLDT LDDT HDV HDGV HDDV.712 x PV (by county, Harris County 2000 registration data shown).288 x PV (by county, Harris County 2000 registration data shown).842 x LDT (by county, Harris County 2000 registration data shown).158 x LDT (by county, Harris County 2000 registration data shown).9944 x LDTl (EPA MOBILE6 default).0056 x LDTl (EPA MOBILE6 default) SU2+SU3+SU4+SE3+SE4+SE5+SE6+SD5+SD6+SD7.369 x HDV (by county, Harris County 2000 registration data shown).631 x HDV (by county, Harris County 2000 registration data shown) Category conversion factors and sources: LDGV LDGTl LDGT2 LDGT3 LDGT4 HDGV2a HDGV3 HDGV4 HDGV5 HDGV6 HDGV7 HDGV8a HDGV8b HDGB LDDV LDDT12 LDDT34 HDDV2b HDDV3 HDDV4 HDDV5 HDDV6 HDDV7 HDDV8a HDDV8b HDDBT HD DBS MC.9977 x LDV (EPA MOBILE6 default).2310 x LLDT (EPA MOBILE6 default).7690 x LLDT (EPA MOBILE6 default).6850 x* HLDT (EPA MOBILE6 default).3150 x HLDT (EPA MOBILE6 default).513 x HDGV (Regional registration data).193 x HDGV (Regional registration data).089 x HDGV (Regional registration data).038 x HDGV (Regional registration data).092 x HDGV (Regional registration data).037 x HDGV (Regional registration data).034 x HDGV (Regional registration data).004 x HDGV (Regional registration data).2045 x B (EPA MOBILE6 default).0023 x LDV (EPA MOBILE6 default).1623 x LDDT (EPA MOBILE6 default).8377 x LDDT (EPA MOBILE6 default).253 x HDDV (Regional registration data).132 x HDDV (Regional registration data).077 x HDDV (Regional registration data).050 x HDDV (Regional registration data).159 x HDDV (Regional registration data).105 x HDDV (Regional registration data).178 x HDDV (Regional registration data).046 x HDDV (Regional registration data).3253 x B (EPA MOBILE6 default).4702 x B (EPA MOBILE6 default) MC (default subtracted from LDGV, no conversion) This procedure is performed as described for weekdays. TxDOT vehicle classification data are only collected for weekdays (Monday through Thursday). (No seasonal changes are assumed.) 23

24 Table 14 HGA 1990 Weekday VMT Mix Estimate by Time Period and Roadway Functional Classification Group OBS TP FC P LDGV P LDGTl P LDGT2 P LDGT3 P LDGT4 P HDGV2B P HDGV 3 P HDGV 4 P HDGV AM Peak AM Peak AM Peak Mid Day Mid Day Mid Day Ovr Nite Ovr Nite Ovr Nite PM Peak PM Peak PM Peak Art Col Fway Art Col Fway Art Col Fway Art Col Fway OBS P HDGV 6 P HDGV 7 P HDGV8A P HDGV8B P LDDV P LDDT12 P HDDV2B P HDDV 3 P HDDV 4 P HDDV OBS P HDDV 6 P HDDV 7 P HDDV8A P HDDV8B P MC P HDGB P HDDBT P HDDBS P LDDT

25 OBS TOTAL TP FC P LDGV P HDDV P HDGV P BUS ,496 5,925 2,556, ,602 11,020 4,052, ,124 6,256 2,737, ,090 10,741 3,440,997 =========== 14,274,816 AM Peak AM Peak AM Peak Mid Day Mid Day Mid Day Ovr Nite Ovr Nite Ovr Nite PM Peak PM Peak PM Peak Art Col Fway Art Col Fway Art Col Fway Art Col Fway N Vt

26 Table 15 HGA 2005 Weekday VMT Mix Estimate by Time Period and Roadway Functional Classification Group OBS TP FC P LDGV P LDGTl P LDGT2 P LDGT3 P LDGT4 P HDGV2B P HDGV 3 P HDGV 4 P HDGV AM Peak AM Peak AM Peak Mid Day Mid Day Mid Day Ovr Nite Ovr Nite Ovr Nite PM Peak PM Peak PM Peak Art Col Fway Art Col Fway Art Col Fway Art Col Fway OBS P HDGV 6 P HDGV 7 P HDGV8A P HDGV8B P LDDV P LDDT12 P HDDV2B P HDDV 3 P HDDV 4 P HDDV OBS P HDDV 6 P HDDV 7 P HDDV8A P HDDV8B P MC P HDGB P HDDBT P HDDBS P LDDT

27 OBS TOTAL TP FC P LDGV P HDDV P HDGV P BUS 1 308,496 AM Peak Art ,925 AM Peak Col ,556,903 AM Peak Fway ,602 Mid Day Art ,020 Mid Day Col ,052,479 Mid Day Fway ,124 Ovr Nite Art ,256 Ovr Nite Col ,737,183 Ovr Nite Fway ,090 PM Peak Art ,741 PM Peak Col ,440,997 PM Peak Fway =========== 14,274,816

28 Table 16 HGA 2007 Weekday VMT Mix Estimate by Time Period and Roadway Functional Classification Group OBS TP FC P LDGV P LDGTl P LDGT2 P LDGT3 P LDGT4 P HDGV2B P HDGV 3 P HDGV 4 P HDGV 5 1 AM Peak 2 AM Peak 3 AM Peak 4 Mid Day 5 Mid Day 6 Mid Day 7 Ovr Nite 8 Ovr Nite 9 Ovr Nite 10 PM Peak 11 PM Peak 12 PM Peak Art Col Fway Art Col Fway Art Col Fway Art Col Fway OBS P HDGV 6 P HDGV 7 P HDGV8A P HDGV8B P LDDV P LDDT12 P HDDV2B P HDDV 3 P HDDV 4 P HDDV 5 N OBS P HDDV 6 P HDDV 7 P HDDV8A P HDDV8B P MC P HDGB P HDDBT P HDDBS P LDDT

29 OBS TOTAL TP FC P LDGV P HDDV P HDGV P BUS 1 308,496 AM Peak Art ,925 AM Peak Col ,556,903 AM Peak Fway ,602 Mid Day Art ,020 Mid Day Col ,052,479 Mid Day Fway ,124 Ovr Nite Art ,256 Ovr Nite Col ,737,183 Ovr Nite Fway ,090 PM Peak Art ,741 PM Peak Col ,440,997 PM Peak Fway =========== 14,274,816

30 ESTIMATION OF EMISSIONS FACTORS The MOBILE6 model was applied to calculate county-specific emissions factors (g/mi) of VOC, CO, and NOx for each of the evaluation years by speed, emissions type (i.e., emissions factor subcomponent), hour, MOBILE6 road type, and vehicle type. 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 HGA peak ozone season climatic conditions, and the HGA vehicle fleet, activity, and emissions control programs corresponding to the particular evaluation. The following emissions factors documentation discusses the MOBILE6 input/output files, summarizes the control programs modeled, describes the aggregation level of the applied MOBILE6 emissions factors, briefly describes all of the MOBILE6 commands that may affect emissions factor calculations, and identifies the commands that were applied. The non-default (i.e., local) inputs applied are identified as well as the EPA defaults used. The details of the development of the locality-specific inputs are provided. Also, the emissions factor postprocessing procedures are described. MOBILE6 Input and Output Files The MOBILE6 commands and particular 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 POLFAC6 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 output tables. (RATEADJ6 and RATEADJV6 were applied to POLFAC6 output where post-processing of emissions factors was required, discussed later.) The final products of the emissions factor modeling are 40 hourly emissions factor files, i.e., one hourly emissions factor table for each county for the five evaluations: 1990 base year, 2005 pre-90 control, 2005 control strategy, 2007 pre-90 control, and 2007 control strategy. All of the MOBILE6 input files and output files (MOBILE6 emissions factor tables developed with POLFAC6, RATEADJ6, and RATEADJV6) were previously provided to TNRCC electronically (on CD-ROM). The CD-ROM volume names and MOBILE6 input and output file names are listed in Appendix A. 30

31 Control Programs Modeled (And Emissions Factor Post Processing Summary) Table 17 summarizes the controls modeled for each emissions factor analysis and identifies the control programs whose impacts must be modeled by post-processing of MOBILE6 emissions factors. Table 17 Control Programs Modeled in MOBILE6 Emissions Factors For 1990, 2005, and 2007 ROP Emissions Inventories Emissions Factor Analysis Controls Modeled Emissions Factor Post- Processing Required For: Pre-90 FMVCP 1990 Base Year 1990 State program (ATP, Harris County), ATP (two-part) (estimated actual RVP applied). Pre-90 FMVCP, 2005 Pre-90 Control* Federal 1992 Summertime RVP limit, ATP (two-part) 1990 State programs (ATP, Harris County). Pre-90 FMVCP, Post-1990 FMVCP, ATP (two-part) 2005 Control Strategy SummerRFG, l/m, ATP May 1 start 2005 State programs (l/m, ATP, LED; all LED HGA). Pre-90 FMVCP, 2007 Pre-90 Control* Federal 1992 Summertime RVP limit, ATP (two-part) 1990 State programs (ATP, Harris County). Pre-90 FMVCP, Post-1990 FMVCP, 2007 Control Strategy Summer Reformulated Gasoline, 2007 State programs (l/m, ATP, LED; all HGA). l/m, ATP May 1 start LED *Applied in both the 1990 adjusted base year emissions inventories, and the future case Pre-90 Control emissions inventories. All FMCPs were modeled (this is the MOBILE6 default), except for the future year Pre-90 Control scenarios (for which the NO CLEAN AIR ACT command was applied, as discussed on Page 65). Also modeled were the federal programs to offset heavy-duty diesel (HDDV) defeat device effects-the low emissions rebuild program, and the HDDV 2004 standard pull-ahead program (this is the MOBILE6 default). The Reformulated Gasoline (RFG) program, the vehicle Inspections and Maintenance (I/M) programs, Anti-Tampering Programs (ATP), and the Texas Low-Emissions Diesel (LED) Fuel Program were modeled as well. 31

32 Post-processing of MOBILE6 emissions factors was required to properly model the ATP and I/M programs, as well as to model the impacts of the low-emissions diesel fuel. The limits of MOBILE6 as related to the ATP, I/M, and diesel fuel modeling requirements for this analysis, and the post-processing procedures applied to overcome these limits are discussed in more detail starting on Page 66. Aggregation Level of MOBILE6 Emissions Factors Each POLF AC6 emissions factor table, for a particular county and calendar day, provides the 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. MOBILE6 vehicle type, emissions type, and roadway type classifications are described in Tables 18 through 20. Tables 21and22 show the speeds and sequence for hourly time periods, respectively. The 28 MOBILE6 vehicle types as defined by fuel-type (gasoline or diesel) and GVWR category, are shown in sequence by EPA vehicle type number in Table

33 Table 18 Complete MOBILE6 Vehicle Classifications Number Abbreviation Description 1 LDGV Light-Duty Gasoline Vehicles (Passenger Cars) 2 LDGTl Light-Duty Gasoline Trucks 1 (0-6,000 lbs. GVWR, 0-3,750 lbs. L VW) 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 AL VW 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 land 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 HD DBS Diesel School Buses 28 LDDT34 Light-Duty Diesel Trucks 3 and 4 (6,001-8,500 lbs. GVWR) Source: MOBILE6 User's Guide (EPA, January 2002) 33

34 The eight MOBILE6 emissions type classifications are shown in Table 19. Expanding these emissions types by individual pollutant yields 12 pollutant-specific emissions types. In addition to these 12 pollutant-specific emissions types, POLFAC6 emissions factor tables contain the three composite emissions factors (i.e., one for each pollutant). Thus, POLFAC6 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 accounted for as an area source emissions category. However, only the composite emissions factors for each pollutant were used to calculate emissions. Number Abbreviation Description Table 19 MOBILE6 Emission Type Classifications Pollutants 1 Running Exhaust Running Emissions HC,CO,NOx All Vehicle Classes 2 Start Exhaust Engine Start Emissions (trip start) HC,CO,NOx LDplusMC 3 Hot Soak Evaporative Hot Soak Emissions (trip end) HC Gas, inc. MC 4 Diurnal Evaporative Diurnal Emissions (heat rise) HC Gas, inc. MC 5 Resting Evaporative Resting Loss Emissions (leaks and seepage) HC Gas, inc.mc 6 Run Loss Evaporative Running Loss Emissions HC Gas, less MC 7 Crankcase Evaporative Crankcase Emissions (blow-by) HC Gas, inc. MC 8 Refueling Evaporative Refueling Emissions (fuel displacement and spillage) Source: MOBILE6 User's Guide (EPA, January 2002) HC Gas, less MC 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. The driving cycle (or roadway type) descriptions are provided in Table 20 (see numbers one through four). 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 POLFAC6 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 POLF AC6 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 POLFAC6 to facilitate the geographical allocation of the link-emissions estimates by the roadway link coordinates. 34

35 Table 20 MOBILE6 Roadway Classifications 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 Source: MOBILE6 User's Guide (EPA, January 2002) Not Applicable (For start and some evaporative emissions) The 14 speeds for calculating and tabulating the MOBILE6 freeway and arterial emissions factors are are presented in Table 21. Later in the emissions estimation process, emissions factors for average link speeds that are not represented in the 14 speeds as tabulated, are calculated by interpolation (except for those link 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 applied, respectively). The MOBILE6 Local and Ramp road type emissions factors are not speed sensitive and are each characterized by one average speed. (Although calculated and tabulated by POLF AC6, the single-speed Local and Ramp emissions factors are not applied in this analysis.) 35

36 Table 21 Speeds for POLFAC6 Tabulated MOBILE6 Emissions Factors Number Speed mph 2 5mph 3 lomph 4 15mph 5 20mph 6 25mph 7 30mph 8 35mph 9 40mph 10 45mph 11 50mph 12 55mph 13 60mph 14 65mph 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. For this analysis, hourly input values to MOBILE6 are representative of the calendar day. The hourly temperature inputs for each MOBILE6 run, for instance, are from one calendar day, as opposed to values spanning two days from 6 a.m. on one day to 6 a.m. on the next day. Table 22 shows the MOBILE6 sequence for hourly inputs and the resulting chronological order for calendar day hourly input as applied for this analysis. 36

37 TABLE22 General Sequence for Calendar Day Hourly* Inputs to MOBILE6 MOBILE6 Input Sequence Number Abbreviation Description Chronological Order 1 6 a.m. 6 a.m. through 6:59 a.m a.m. 7 a.m. through 7:59 a.m a.m 8 a.m. through 8:59 a.m a.m. 9 a.m. through 9:59 a.m a.m. 10 a.m. through 10:59 a.m a.m. 11 a.m. through 11 :59 a.m Noon 12 p.m. through 12:59 p.m p.m. 1 p.m. through 1 :59 p.m p.m. 2 p.m. through 2:59 p.m p.m. 3 p.m. through 3:59 p.m p.m. 4 p.m. through 4:59 p.m p.m. 5 p.m. through 5:59 p.m p.m. 6 p.m. through 6:59 p.m p.m. 7 p.m. through 7:59 p.m p.m. 8 p.m. through 8:59 p.m p.m. 9 p.m. through 9:59 p.m lop.m. 10 p.m. through 10:59 p.m p.m. 11 p.m. through 11 :59 p.m Midnight 12 a.m. through 12:59 a.m a.m. 1 a.m. through 1 :59 a.m a.m. 2 a.m. through 2:59 a.m a.m. 3 a.m. through 3:59 a.m a.m. 4 a.m. through 4:59 a.m a.m. 5 a.m. through 5:59 a.m. 6 * For some MOBILE6 hourly input parameters, overnight hours are grouped. Application of MOBILE6 Commands and Associated Input Parameters All of the MOBILE6 commands that may affect calculating emissions factors (excluding commands such as those that affect only the output format or content) are listed and described in the Tables 23 through 28. Respectively, these six tables are: MOBILE6 External Conditions, MOBILE6 Vehicle 37

38 Fleet Characteristics, MOBILE6 Activity, MOBILE6 State Programs, MOBILE6 Fuels, and MOBILE6 Alternative Emissions Regulations and Control Measures. In these tables, parameters associated with each MOBILE6 command are labeled as either EPA default, locality-specific, NOT APPLIED, or are otherwise described. The tabulated commands where the associated input parameters are labeled only as "EPA default" are not input for this analysis-mobile6 does not require a user-input command to apply these MOBILE6 default values. The "Input Parameter Values" description for each command applies to all five emissions factor evaluations, unless otherwise noted. The procedures used to develop the locality-specific inputs to MOBILE6 are detailed following the six MOBILE6 input category tables. 38

39 Table23 MOBILE6 External Conditions Command Function/Description Input Parameter Values Base Year: 1990 Identifies calendar year for which emissions 2005 Pre-90 Control: 2005 CALENDAR YEAR factors are to be calculated. (Required to run 2005 Control Strategy: 2005 model) Pre-90 Control: Control Strategy: 2007 EVALUATION MONTH MIN/MAX TEMPERATURE Provides option of calculating January 1 or July 1 emission factors for the calendar year of evaluation. Sets minimum and maximum daily temperatures. (Required to run model if the HOURLY TEMPERATURES command is not used.) 7 (for July) NOT APPLIED. (See HOURLY TEMPERATURES.) Locality-Specific. Regional, Allows temperatures input for each hour of HOURLY hourly averages from the 10 day (required to run model if MIN/ MAX TEMPERATURES highest ozone exceedence TEMPERATURE command is not used). days for 1997 through ALTITUDE Specifies high - or low-altitude for modeling area. EPA Default (low altitude). ABSOLUTE HUMIDITY Environmental Effects on Air Conditioning: Used to specify daily average humidity (which directly affects NOx emissions). Locality-Specific. Regional MOBILE6 also converts absolute humidity daily absolute humidity value to heat index which affects HC and CO developed from the 10 highest emissions for the portion of the fleet that ozone exceedence days for MOBILE6 determines is using air 1997 through conditioning. Commands used by MOBILE6 to model the extent of vehicle air-conditioning usage. CLOUD COVER Specifies average percent cloud cover for EPA Default. given day. PEAK SUN Specifies mid-day hours with peak sun EPA Default. intensity. SUNRISE/SUNSET Allows user to specify time of sunrise, Locality-Specific. sunset. 39

40 Table 24 MOBILE6 Vehicle Fleet Characteristics Command Function/Description Input Parameter Values REG DIST DIESEL FRACTIONS Allows the user to supply registration distributions by age for any of the 16 composite (combined gasoline and diesel) vehicle types. Permits user to supply locality-specific diesel fractions for 14 of the 16 composite vehicle categories by age. Locality-Specific/EPA Default. July 2001 TxDOT eight-county aggregate registrations for all evaluations are applied except for buses for which MOBILE6 default is used. Locality-Specific/EPA Default. TxDOT registrations specify gasoline and diesel for eight HDV classes. TxDOT eight-county aggregate July, 2001 HDV Diesel fractions are adjusted for and applied to the evaluation year (1990, 2005, 2007). EPA evaluation year defaults are applied for the other six classes. MILE Allows the user to supply the annual ACCUM mileage accumulation rates by vehicle type EPA Default. RATE and age. NGV FRACTION Allows user to specify percent of natural gas vehicles (NGV) in the fleet by type and age certified to operate on either compressed or liquefied natural gas. EPA Default. The EPA default percentage of NGV vehicles in the fleet is zero. Permits the user to enter alternate NGV NGVEF emissions factors for each of the 28 vehicle EPA Default. EPA default is none. types, for running and start emissions. 40

41 Table 25 MOBILE6 Activity Command VMT FRACTIONS VMT BY FACILITY VMTBYHOUR SPEEDVMT AVERAGE SPEED STARTS PER DAY START DIST SOAK DISTRIBUTION HOT SOAK ACTIVITY DIURNSOAK ACTIVITY WE DA TRI LEN DI WE EN TRI LEN DI WEVEHUS Input Parameter Values POST-PROCESSED. VMT mix fractions are applied to link VMT later in the emissions estimation process. NOT APPLIED. EPA default applied, but only used to produce "all road types" daily rates. The "all road types" emissions factors in daily (.rtd) files are not valid; individual "road type" daily rates (unrelated to this command) are valid. Locality-Specific. Regional total VMT fractions by hour produced from the 2007 PREPIN output (post- processed travel model output) for application to all three years. Function/Description Used in MOBILE6 to weight the emissions of various vehicle types into average rates for groupings of vehicle classes. VMT fractions by MOBILE6 road types are used to combine the four individual road type emissions factors into the "all road types" emissions factors. Allows user to allocate VMT fractions by hour of day; applied in conversion of grams per hour (g/hr) to grams per mile (g/mi), as well as in weighting of hourly g/mi rates to get daily emissions factors. Allows user to allocate VMT by average speed (14-preselected: 2.5 and 5 through 65 at 5 mph increments) for arterials and freeways for each hour of the day. Allows a single average speed for combined freeways and arterial for the entire day. Allows the user to specify the average number of engine starts per vehicle per day by vehicle types for weekend days and weekdays. Allows user to allocate engine starts by hour of the day for weekend days and weekdays. Allows the user to enter alternate vehicle soak duration distributions for weekend days and weekdays. Allows users to specify a hot soak duration distribution for each of 14 daily time periods for weekend days and for weekdays. Allows the user to set diurnal soak time distributions for each of 18 daily time periods. Specifies alternate fractions of VMT that occur during trips of various durations at each hour of the average weekday. Specifies hourly alternate fractions of VMT for trips of various lengths for weekend days. Allows the user to direct MOBILE6 to use weekend activity data for calculating emissions factors. Internally applied by POLFAC6 for calculating emissions factors by the 14 MOBILE6 speeds for individual MOBILE6 freeway and arterial road types. NOT APPLIED. EPA Default. Used weekday values. EPA default. Used weekday values. EPA Default. Used weekday values. EPA Default. Used weekday values. EPA Default. Locality-Specific. Used latest regional distributions developed by HGAC. NOT APPLIED. Used HGAC weekday distributions for all days. NOT APPLIED. 41

42 Table 26 MOBILE6 State Programs Command STAGE II REFUELING ANTI-TAMP PROG IIM Commands: I/MPROGRAM IIM MODEL YEARS IIM VEHICLES IIM STRINGENCY IIM COMPLIANCE I/MWAIVER RATES IIM CUTPOINTS IIM EXEMPTION AGE IIM GRACE PERIOD NOI/MTTC CREDITS IIM EFFECTIVENESS IIM DESC FILE Function/Description Allows modeling of at-the-pump refueling emissions. Allows user to model impacts of an antitampering program (ATP). Required for exhaust/evaporative IIM programs. Required for exhaust/evaporative IIM programs. Required for exhaust/evaporative IIM programs. Required for exhaust. Don't use for evaporative. Required for exhaust. Optional for evaporative. Required for exhaust. Optional for evaporative. Optional for exhaust (but required for IM240). Don't use with evaporative. Optional for both exhaust and evaporative. Optional for both exhaust and evaporative. Optional for exhaust. Don't use with evaporative. Optional for exhaust. Don't use with evaporative. Optional for both. Input Parameter Values NOT APPLIED. Accounted for as an area source category. Locality-Specific. Program design by evaluation year and county Base Year: Pre-90 Control: Control Strategy: Pre-90 Control: Control Strategy: 2007 Locality-Specific. Program design, by county and evaluation year Base Year: No IIM 2005 Pre-90 Control: No IIM 2005 Control Strategy: Pre-90 Control: No IIM 2007 Control Strategy:

43 Table 27 MOBILE6 Fuels II Command Function/Description Input Parameter Values Allows users to specify: 1) Conventional Gasoline East Tier 2 sulfur phase-in schedule (includes Texas), Option 1: 1990 Base Year 2005 Pre-90 Control 2007 Pre-90 Control FUEL PROGRAM SULFUR CONTENT OXYGENATED FUELS FUELRVP 2) Reformulated Gasoline (RFG), 3) Conventional Gasoline West Tier 2 sulfur geographical phase-in area (GPA) schedule (not applicable to Texas), or 4) sulfur content for gasoline after Allows user to apply alternate sulfur content to conventional gasoline through calendar year Permits the user to model the effects of oxygenated gasoline on exhaust emissions for all gasoline-fueled vehicle types. Allows user to specify fuel RVP for area being modeled (required to run model). Option Control Strategy 2007 Control Strategy (This option overrides the FUEL RVP command input.) NOT APPLIED. NOT APPLIED. See FUEL PROGRAM, above. Locality-Specific Base Year: 8.3 estimated actual 2005 Pre-90 Control: 7.8 Fed. limit 2005 Control Strategy: RFG overrides 2007 Pre-90 Control: 7.8 Fed. limit 2007 Control Strategy: RFG overrides SEASON Identifies effective season for RFG calculation regardless of month modeled. BP A Default. BP A default is summer for July month of evaluation. 43

44 Table 28 MOBILE6 Alternative Emissions Regulations and Control Measures Command Function/Description Input Parameter NO CLEAN AIR ACT Models vehicle emissions as if the Federal Clean Air Act Amendments of 1990 had not been implemented. NOT APPLIED: 1990 Base Year 2005 Control Strategy 2007 Control Strategy APPLIED: 2005 Pre-90 Control 2007 Pre-90 Control HDDV NOx Off-Cycle Emissions Effects: NO DEFEAT DEVICE Tums off the effects of the HDD vehicle NOx NOT APPLIED off-cycle emissions effects (defeat device emissions). NONOXPULL Tums off HDD NOx emissions reduction effects NOT APPLIED AHEAD of Pull-Ahead program. NO REBUILD Tums off HDD NOx emissions reduction effects NOT APPLIED of Rebuild program. REBUILD EFFECTS Allows user to change Rebuild program NOT APPLIED effectiveness rate. Tier 2 Emission Allows the overriding of the default Tier 2 Standards and Fuel emissions standards and fuel requirements Requirements: settings. NOTIER2 Disables Tier 2 requirements. NOT APPLIED T2 EXH PHASE-IN Allows alternate Tier 2 exhaust standard phasein schedules. T2 EV AP PHASE-IN Allows alternate Tier 2 evaporative standard phase-in schedules. T2CERT Allows user to specify alternate Tier 2 50,000 mile certification standards. 94+LDG IMPLEMENTATON NO 2007 HDDV RULE Allows use of alternate 1994 and later fleet penetration fractions for light-duty gasoline vehicles under the Tier 1, NLEV (or California LEV 1), and Tier 2 emission standard programs. Disables 2007 heavy-duty vehicle emissions standards. NOT APPLIED NOT APPLIED 44

45 External Conditions-Locality-Specific Inputs to MOBILE6 MOBILE6 local inputs for hourly temperatures, daily average humidity, and sunrise and sunset times were developed and applied by calendar day based on local (central daylight) time. TNRCC developed the values and TTI formatted them for input to MOBILE6. These input values were developed based on climate data from the 10 highest ozone exceedence days from the period 1997 through TNRCC chose this period to replace the original 1990 base year exceedence period data because the old data did not include relative humidity which is used to develop the user-input locality specific MOBILE6 absolute humidity input. Temperatures (HOURLY TEMPERATURES Command) TNRCC developed ambient ozone season hourly temperatures (degrees Fahrenheit) for input to MOBILE6 for the eight-county region. The input temperatures are hourly averages from the 10 highest ozone exceedence days for the period 1997 through TNRCC used the George Bush-Houston Intercontinental Airport (IAH) weather station data. 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. A summary of the temperature inputs are shown in Table

46 Table 29 HGA Peak Ozone Season Average Hourly Temperatures Hour Average Temperature 6 a.m. through 6:59 a.m a.m. through 7:59 a.m a.m. through 8:59 a.m a.m. through 9:59 a.m a.m. through 10:59 a.m a.m. through 11 :59 a.m p.m. through 12:59 p.m p.m. through 1 :59 p.m p.m. through 2:59 p.m p.m. through 3:59 p.m p.m. through 4:59 p.m p.m. through 5:59 p.m p.m. through 6:59 p.m p.m. through 7:59 p.m p.m. through 8:59 p.m p.m. through 9:59 p.m p.m. through 10:59 p.m p.m. through 11 :59 p.m a.m. through 12:59 a.m a.m. through 1:59 a.m a.m. through 2:59 a.m a.m. through 3:59 a.m a.m. through 4:59 a.m a.m. through 5:59 a.m Humidity (ABSOLUTE HUMIDITY Command) The ABSOLUTE HUMIDITY command was applied to specify the peak ozone season daily average humidity value. The units for absolute humidity are grains of water per pound of dry air. The peak ozone season absolute humidity value is

47 TNRCC developed and provided the average daily humidity input to MOBILE6. The period climate data from the IAH weather station, as used to develop the ozone season hourly temperatures, was used to develop the humidity input as well. To produce the "daily" humidity input to MOBILE6, hourly values were first calculated. From the calculated hourly absolute humidity values, a value representative of the day was then produced or selected, such that when applied with the MOBILE6 hourly temperature inputs, no hourly relative humidity values above 100% would result. Hourly relative humidity, hourly temperature, and barometric pressure data were required to develop the absolute humidity input. TNRCC performed hourly absolute humidity calculations using an EPA formula from a spreadsheet found at the EPA MOBILE6 Internet site ( The hourly temperature inputs used for the humidity calculation are those described in the preceding section. Hourly relative humidity values for the calculation were estimated in the same manner as described for the temperatures, that is, they were averaged by hour for the 10 highest ozone exceedence days from 1997 through Barometric pressure was kept constant at inches. Within the bounds of MOBILE6 and EPA guidance (EPA Technical Guidance on the Use of MOBILE6 for Emission Inventory Preparation, January 2002), TNRCC produced the most reasonable daily absolute humidity inputs for each of the eight climate zones for the period of analysis. TNRCC first developed three daily absolute humidity inputs - two of these values are developed based on optional methods from the EPA guidance, and the third value is the average of the two EPA-based values. In addition to ensuring that the daily value chosen was compatible with the MOBILE6 temperature input (i.e., would not result in any hourly relative humidity values over 100%), TNRCC selected the daily absolute humidity value that when applied with the hourly temperature inputs, yielded back-calculated hourly relative humidity values that most closely resembled the hourly averaged observed relative humidity values. The humidity parameter is input in the MOBILE6 command file. 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. TNRCC provided the sunrise and sunset times which are the same for all counties. The times are 7 a.m. and 8 p.m. central daylight time. Vehicle Fleet Characteristics - Locality-Specific Inputs to MOBILE6 Regional (eight-county area) vehicle registration (age) distributions and diesel fractions inputs to MOBILE6 were developed from available TxDOT registration data. The regional age distributions developed from the July, 2001 registration distributions from the TxDOT data were applied for all three evaluation years, 1990, 2005, and Individual regional diesel fractions for the 1990, 2005, and 2007 evaluations were developed from the July 2001 registrations. Where necessary, the regional diesel fractions for 1990 were projected back and the regional diesel fractions for 2005 and 2007 were forecast. The assumption used, in the future cases, was that the most recent fractions, by vehicle type, were the same for the future 47

48 years (e.g., mid-year 2001 fractions were applied to 2002 through 2007). For the historical case, the oldest model year fraction was applied for older model year vehicle classes for which data were not available. The application of local registration distributions and diesel fractions for these emissions inventory analyses 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 for all three evaluation years (i.e., ensuring that the average age for combined age distributions for future years does not exceed the average age from the latest age distributions available), and uses the most recent diesel fractions available as the projected fractions for future years. Vehicle Registration Distributions (REG DIST Command) TTI developed TxDOT eight-county aggregate MOBILE6 age distributions fractions input 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 2001 registrations for: LDV, LDT12, LDT34, MC, HDGT, HDDT; February 2002 registrations for: Gas: HDV2B, HDV3, HDV4, HDV5, HDV6, HDV7, HDV8A, HDV8B; and Diesel: HDV2B, HDV3, HDV4, HDV5, HDV6, HDV7, HDV8A, HDV8B. The July 2001 registrations are for: automobiles, light duty trucks (LDT12, corresponding to MOBILE6 classes LDTl 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 February 2002 gasoline and diesel HDV classes (eight each) comprise the July 2001 HDGT and HDDT classes represented in the July 2001 data set, respectively, and correspond to the eight HDV weight classes for numbers six through 13 in Table

49 Number s Table 30 Composite Vehicle Classes for Vehicle Registration Data (REG DIST Command) Abbreviation LDV LDTl LDT2 LDT3 LDT4 HDV2B HDV3 HDV4 HDV5 HDV6 HDV7 HDVSA HDVSB HDBS HDBT MC Description Light-Duty Vehicles (Passenger Cars) Light-Duty Trucks 1 (0-6,000 lbs. GVWR, 0-3,750 lbs. LVW) Light-Duty Trucks 2 (0-6,000 lbs. GVWR, 3,751-5,750 lbs. LVW) Light-Duty Trucks 3 (6,001-S,500 lbs. GVWR, 0-5,750 lbs. AL VW*) Light-Duty Trucks 4 (6,001-S,500 lbs. GVWR, 5,751 lbs. and greater ALVW) Class 2b Heavy-Duty Vehicles (S,501-10,000 lbs. GVWR) Class 3 Heavy-Duty Vehicles (10,001-14,000 lbs. GVWR) Class 4 Heavy-Duty Vehicles (14,001-16,000 lbs. GVWR) Class 5 Heavy-Duty Vehicles (16,001-19,500 lbs. GVWR) Class 6 Heavy-Duty Vehicles (19,501-26,000 lbs. GVWR) Class 7 Heavy-Duty Vehicles (26,001-33,000 lbs. GVWR) Class Sa Heavy-Duty Vehicles (33,001-60,000 lbs. GVWR) Class Sb Heavy-Duty Vehicles (>60,000 lbs. GVWR) School Buses Transit and Urban Buses Motorcycles (All) * AL VW = Adjusted Loaded Vehicle Weight: The adjusted loaded vehicle weight is the numerical average of the vehicle curb weight and the gross vehicle weight rating (GVWR). Source: MOBILE6 User's Guide (EPA, January 2002) After combining registrations to the eight-county area level, there were four main steps to developing the HGA MOBILE6 registration distribution inputs for the 14 non-bus vehicle classes. The first step in the process transforms the 16 HDV (eight gasoline and eight diesel) February 2002 registrations data set to an estimated July, 2001 registrations data set. The next step results in July 2001 registrations by the 25 age groups for 12 of the 16 composite (by fuel) vehicle classes (eight HDV, LDV, LDT12, LDT34, MC). The third step converts the registrations from numbers of vehicles registered, to fractions registered by age for each of the 12 classes. The registrations are then expanded from 12 classes to 14. To estimate July 2001 HDV registrations from the 2002 HDV registrations data, the 2002 model year registrations were first dropped from the data set to yield approximate end-of-year 2001 registrations for the latest model year. Mid-year scaling factors were then applied to the approximate end-of-year 2001 model year HDV registrations. These scaling factors (particular to fuel-type) are the 2001 model year HDT registrations from the July 2001 data set divided by the 49

50 sum total of the HDV sub-class, end-of-year 2001 model year registrations. The July 2001 scaling factors were then applied to the 2001 model year (approximate end-of-year) individual eight HDV class registrations, as appropriate by fuel type, to obtain the mid-year 2001 registrations estimates for the 16 HDV fuel type-specific classes. No vehicle scrappage estimates or vehicle migration estimates were made for the period from July 2001 to February 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 1977 and older registrations were summed to yield the "age 25 and older" registrations for each of the 12 composite vehicle classes: eight HDVs, LDV, LDT12, LDT34, and MC. Conversion of the registrations from numbers of vehicles to fractions of vehicles by age was performed 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 2001 estimated district-level registration distribution fractions for the 12 composite classes were expanded to 14 classes: LDV, LDTl, LDT2, LDT3, LDT4, MC, HDV2B, HDV3, HDV4, HDV5, HDV6, HDV7, HDV8A, and HDV8B. The LDT12 age fractions, were used for both the MOBILE6 LDTl and LDT2 classes and the LDT34 age fractions were used in MOBILE6 for both the LDT3 and LDT4 classes. The MOBILE6 vehicle registration distributions are input from external data files. Table 31 shows the eight-county aggregate age distributions input to MOBILE6 as applied in these base and future case analyses. 50

51 Table 31 HGA Regional Vehicle Registration Distributions REG DIST * HGA * Calculated from July 2001 Registration data and February 2002 HDV data * LDV * LDTI * LDT * LDT * LDT * HDV2B * HDV * HDV * HDV * HDV6 IO * HDV * HDV8A * HDV8B * HOBS is MOBILE6 default * HDBT is MOBILE6 default *MC (\ 1\11\1\'1(\1\1C~'ln1\1 'la~ (\ """O< (\ 1\41\1\'J 51

52 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 diesel fractions are entered by the user, 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 For 1971 and earlier model years, the default diesel fractions are assumed to be the same as the 1972 model year fractions. For the 1997 and later model years, the default diesel fractions are assumed to be the same as the 1996 model year fractions. TTI used a combination of estimated HGA county-aggregate diesel fractions and EPA default diesel fractions to model the 1990, 2005, and 2007 ROP emissions factors. Table 32 shows the MOBILE6 diesel fractions input categories and the corresponding data source for each category. The diesel fraction estimates were calculated based on HGA aggregate TxDOT individual diesel and gasoline vehicle registrations for the eight HDV (HDV2b through HDV8b) weight classes. As discussed previously, these TxDOT registrations data were adjusted to represent registrations as of July, 2001 (see registrations distributions discussion). To obtain the set of HDV diesel fractions by model year, the by-model-year diesel registrations were divided by the associated sum of the gasoline and diesel registrations. This procedure was performed for each HDV composite vehicle class and model year. 52

53 Table32 Source of Diesel Fractions for Composite Vehicle Types (DIESEL FRACTIONS Command) Number s Abbreviation Description Source of Fractions LDV Light-Duty Vehicles EPA MOBILE6 Evaluation Year Default LDTl Light-Duty Trucks 1 EPA MOBILE6 Evaluation Year Default LDT2 Light-Duty Trucks 2 EPA MOBILE6 Evaluation Year Default LDT3 Light-Duty Trucks 3 EPA MOBILE6 Evaluation Year Default LDT4 Light-Duty Trucks 4 EPA MOBILE6 Evaluation Year Default HDV2B Class 2b Heavy-Duty Vehicles TxDOT February, 2002 Registrations HDV3 Class 3 Heavy-Duty Vehicles TxDOT February, 2002 Registrations HDV4 Class 4 Heavy-Duty Vehicles TxDOT February, 2002 Registrations HDV5 Class 5 Heavy-Duty Vehicles TxDOT February, 2002 Registrations HDV6 Class 6 Heavy-Duty Vehicles TxDOT February, 2002 Registrations HDV7 Class 7 Heavy-Duty Vehicles TxDOT February, 2002 Registrations HDVSA Class Sa Heavy-Duty Vehicles TxDOT February, 2002 Registrations HDVSB Class Sb Heavy-Duty Vehicles TxDOT February, 2002 Registrations HDBS School Buses EPA MOBILE6 Evaluation Year Default The HDV diesel fractions (developed from estimated mid-year 2001 county-specific HDV registration distributions) were projected from 2001to2005, and to 2007, by applying the latest diesel fraction (2001) to each of the future years (2002 through 2005, and through 2007); an equal number of diesel fractions were dropped from the end (oldest model years) of the data set. To estimate the 1990 base year diesel fractions, the diesel fractions for 1991 model years through 2001 were dropped from the data set; the fractions for oldest model year in the data set, 1977, were applied to each of the older model years to complete the 25-year model data set. These estimated HDV diesel fractions for 1990, 2005, and 2007 were then combined with the July evaluation-year specific EPA default diesel fractions for the remaining vehicle classes. Diesel fractions are entered in the MOBILE6 command file. The estimated diesel fractions as applied for the 1990, 2005 and 2007 ROP emissions factors modeling, are shown in Tables 33, 34, and 35, respectively. 53

54 Table Diesel Fractions * 1990 DIESEL SALES FRACTIONS ESTIMATES FOR HGA 8-COUNTY GROUP * HOV fractions are estimated from TxDOT registration data (7/01, 2/02 data sets); * LDV, LDT, and Bus fractions are EPA defaults DIESEL FRACTIONS : O.Gl O.Ql O.o

55 Table Diesel Fractions * 2005 DIESEL SALES FRACTIONS ESTIMATES FOR HGA 8 COUNTY GROUP * HDV fractions are estimated from TxDOT registration data (7/01, 2/02 data sets); * LDV, LDT, and Bus fractions are EPA defaults DIESEL FRACTIONS : O.Ql 150O.Ql Ql

56 Table Diesel Fractions * 2007 DIESEL SALES FRACTIONS ESTIMATES FOR HGA 8-COUNTY GROUP * HOV fractions are estimated from TxDOT registration data (7/01, 2/02 data sets); * LDV, LDT, and Bus fractions are EPA defaults DIESEL FRACTIONS :

57 Activity - Locality-Specific Inputs to MOBILE6 The user-input locality-specific activity parameters applied to develop the MOBILE6 hourly emissions factors for this analysis are the regional (eight-county) fleet total hourly VMT fractions, and regional average hourly weekday trip length distributions. Additionally, hourly fractions of VMT by the 14 speeds input for arterials and freeways were used. The hourly VMT fractions input to MOBILE6 were developed from the fully-adjusted 2007 hourly ozone season weekday VMT data sets. The hourly weekday trip length distributions were developed by HGAC. VMT Fractions (also known as VMTmix) 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.) The VMT by hour fractions were developed for the eight-county area using the 2007 VMT estimates by county. The hourly link VMT total for each hour was divided by the daily link VMT total. The resulting hourly, weekday VMT fractions were applied for the 1990, 2005, and 2007 emissions factor analyses. These fractions are input to MOBILE6 as an external data file. The regional hourly VMT fractions are shown in Table 36 57

58 Table36 HGA Regional Hourly VMT Fractions MOBILE6 Input Hour Fleet Total VMT Fraction 6 a.m. through 6:59 a.m a.m. through 7:59 a.m a.m. through 8:59 a.m a.m. through 9:59 a.m a.m. through 10:59 a.m a.m. through 11 :59 a.m p.m. through 12:59 p.m p.m. through 1 :59 p.m p.m. through 2:59 p.m p.m. through 3:59 p.m p.m. through 4:59 p.m p.m. through 5:59 p.m p.m. through 6:59 p.m p.m. through 7:59 p.m p.m. through 8:59 p.m p.m. through 9:59 p.m p.m. through 10:59 p.m p.m. through 11:59 p.m a.m. through 12:59 a.m a.m. through 1:59 a.m a.m. through 2:59 a.m a.m. through 3:59 a.m a.m. through 4:59 a.m a.m. through 5:59 a.m 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 POLFAC6 program (that is, no user- input speed commands or data parameter values are required when producing MOBILE6 emissions factors tables with POLFAC6). POLFAC6 uses the SPEED VMT inputs to produce the individual Freeway and Arterial hourly emissions factors indexed by the 14 MOBILE6 speed bin speeds. 58

59 To model the freeway and arterial emissions factor for each of the individual 14 speeds, POLFAC6 creates 14 VMT by Speed external data file input setups, one for each of the 14 speeds. Each of the 14 input files, or setups, allocates 100 percent of the VMT to one of the 14 speeds (and thus 0 percent to the other 13) for both arterials and freeways. Execution of POLFAC6 produces the 14 speed scenario setups and the desired freeway and arterial emissions factors for each of the 14 MOBILE6 speed bin speeds. Trip Length Distributions by Hour of Day (WE DA TRI LEN DI Command) The weekday trip length distributions (TLDs) input to MOBILE6 are called by the WE DA TRI LEN DI command. TLDs specify the percentage of average weekday (or weekend) VMT that occurs during trips of different durations at each hour of the day. The VMT distributions are entered as percentages for six trip length ranges, and must sum to 100 percent. The percentage values correspond to VMT accumulated within the trip durations: Under 10 minutes, minutes, minutes, minutes, minutes, and 51 minutes and longer. HGA regional TLDs were applied for this analysis (Table 37). These TLDs were taken from the report "Conformity Determinations for The 2022 Metropolitan Transportation Plan and the Transportation Improvement Program for Houston-Galveston Transportation Management area," March 23, 2000 prepared by HGAC. The HGA area-wide hourly TLD data are input to MOBILE6 in an external data file. 59

60 Table 37 HGA Percent of VMT by Trip Length, Hourly Hour Trip Length Ranges (minutes) < >51 6 a.m a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m. through 5 a.m State Programs For this analysis, the State Programs inputs to MOBILE6 model the effects of vehicle ATPs and exhaust and evaporative IIM programs that apply to the gasoline-fueled vehicle classes, except motorcycles. For 1990 base year, 2005 Pre-90 Control, and 2007 Pre-90 Control, Harris County is the only county modeled with ATP, and no counties are modeled with IIM (see summary of controls modeled by emissions factor analysis in Table 17). For 2005 and 2007 control strategy evaluations, all HGA counties are modeled with ATP and IIM programs. For the development of MOBILE6 ATP and IIM program setups and post-processing procedures, the eight HGA counties were grouped according to their exhaust IIM program start dates as: 60

61 Harris (January 1, 1997), Urban (May 1, 2003: Brazoria, Fort Bend, Galveston, Montgomery), and Rural (May 1, 2004: Chambers, Liberty, and Waller). For the Urban and Rural county categories, the ATP start dates are assumed to coincide with the exhaust IIM program start dates for those counties. Vehicle ATP (ANTI-TAMP PROG Command) For 1990, 2005, and 2007 Pre-90 Control evaluations, the ATP is composed of two sub-programs - an early model year program and a late model year program. For the 2007 Control Strategy evaluation, the earlier model year ATP is phased out. Appendix E describes the ATP setups. The emissions factor post-processing procedures required to model the full effects of the two-part ATP are discussed with the other post-processing requirements beginning on Page 64. The MOBILE6 ATP setups are entered in the MOBILE6 command file. JIM Programs Appendix F describes the HGA IIM setups required to model the IIM programs as designed for operation in 2005 and For the 1990 base year, no IIM programs were administered in the HGA. The emissions factor post-processing procedure necessary to model the effects of the May 1 start date for the Urban and Rural counties is described beginning on Page 64. The IIM commands and data parameters were input to MOBILE6 in an external data file called from the command file using the IIM DESC FILE command. Fuels - Locality-Specific Inputs to MOBILE6 User input for fuel effects modeling are for the eight-county group for each evaluation year. The fuel effects are modeled using only the FUELS PROGRAM and FUEL RVP commands and associated input parameters and options, and the NO CLEAN AIR ACT command. The RVP of gasoline is a required input to run MOBILE6, but is not used in the MOBILE6 calculations when the EPA default summer RFG option is modeled. The FUEL RVP input is overridden by the MOBILE6 RFG option. The 1990, 2005 Pre-90 Control, and 2007 Pre-90 Control emissions factors are modeled with the MOBILE6 conventional gasoline east option. The 2005 and 2007 control strategy emissions factors are modeled with the MOBILE6 summer RFG option. Fuel Program (FUEL PROGRAM Command) The MOBILE6 FUEL PROGRAM command provides the user four options for modeling fuels effects. For this analysis, two of the options were used, summer RFG southern region, and the conventional gasoline east option. The selected FUEL PROGRAM option is entered in the MOBILE6 command file. 61

62 The second option, RFG (with the southern volatility region indicated), was modeled for the 2005 and 2007 control strategy analyses. This directs MOBILE6 to model the effects of RFG as defined by the EPA default parameters for the southern volatility region, summer RFG. For this option, EPA default RFG parameter values used in MOBILE6 for 2005 and 2007 are: RVP, South region-6.8 pounds per square inch; Ether Oxygen Content percent by weight; Ether Market Share- 100 percent; Sulfur Content, 2005 average - 90 parts per million (ppm); Sulfur Content, 2007 average -30 ppm; and Sulfur Content, maximum experienced by model year: 2006, ppm; 2004, ppm; 2000 through ppm; and 1999 and older - NI A. The first option, conventional gasoline east, which is also the MOBILE6 default, was modeled for the 1990 bae year. This first option was also used for the 2005 Pre-90 Control and 2007 Pre-90 Control emissions factors, but in combination with the NO CLEAN AIR ACT command. The NO CLEAN AIR ACT command sets the fuel sulfur level to 300 ppm for all model years greater than 1993 (i.e., pre-tier 2 rule levels). In the absence of the NO CLEAN AIR ACT command, the conventional gasoline east 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) The RVP values as applied through use of the FUEL RVP command are listed below for each evaluation Base Year- 8.3 estimated actual; 2005 Pre-90 Control Fed. limit; 2005 Control Strategy- 6.8 (RFG overrides); 2007 Pre-90 Control Fed. limit; and 2007 Control Strategy- 6.8 (RFG overrides). The 1990 base year emissions factors use the estimated actual gasoline RVP value of 8.3 psi. Appendix G shows the EPA procedure and 1990 gasoline survey data used to estimate this input value. The 2005 Pre-90 Control and 2007 Pre-90 Control emissions factors use an RVP of 7.8 psi, the HGA limit from the Federal fuel volatility regulations (summertime gasoline RVP limits beginning in 1992) promulgated in July of 1990 (pre-caaa). For the 2005 and 2007 control strategy emissions factors, the RVP value of 6.8 is entered (MOBILE6 default for summertime RFG option) although it is overridden by the FUEL PROGRAM RFG option. The RVP value is entered in the MOBILE6 command file. 62

63 MOBILE6 Alternative Emissions Regulations and Control Measures Commands The only command used from this section of MOBILE6 commands, is related to the NO CLEAN AIR ACT command. This command allows the modeling of vehicle emissions as if the Federal Clean Air Act Amendments of 1990 had not been implemented. As previously discussed, the ROP plans may not take credit for emissions reductions from pre-90 CAAA FMVCP. To estimate the "noncreditable" emissions reductions, the 1990 adjusted base year emissions inventories relative to the evaluation years (i.e., 2005 and 2007) are calculated. The ABYEI emissions inventories use the 2005 and 2007 Pre-90 Control emissions factors. These emissions factors apply the NO CLEAN AIR ACT command. Use of this command disables the following effects in MOBILE6 (from "User's Guide to MOBILE6.0, EPA, January 2002): The effect of all Federal exhaust tailpipe standards after TierO standards or the 1993 model year will be shut off. All model years subsequent to the 1993 model year will be assigned the 1993 model year emissions factor. The 1993 model year was selected because it is the last year that was unaffected by the CAA amendments. The evaporative emissions benefits from the Enhanced Evaporative Test procedure will be eliminated. This affects running loss, diurnal, hot soak, resting loss, and refueling emissions factors. The emissions benefits from the Supplemental Federal Test Procedure for both off-cycle and air-conditioning emissions effects will be eliminated if the command is issued. The effects of on-board diagnostics (OBD) will be eliminated, and an OBD IIM program will not be allowed. Evaporative OBD IIM programs are also not allowed when this command is used. Only Exhaust and Evaporative IIM programs that existed in calendar year 1990 can be modeled, and they can be modeled for model years 1996 and later. The fuel sulfur level is set to 300 ppm for all model years greater than The detergent gas emissions effect is eliminated. The 1995 model year tampering rates are extended past the 1995 model year I calendar year. For these years, the rates that prevailed in the 1995 model year are used. Cold temperature CO effects are affected. These will be set to 1993 model year rates. 63

64 The following effects are not affected by the NO CLEAN AIR ACT command. Heavy-duty vehicle off-cycle effects (defeat device), and heavy-duty vehicle conversion factors are unaffected by this command. The MOBILE6 correction factors for average speed are unaffected by this command. Facility cycle or roadway effects are unaffected by this command. Fleet effects such as fleet turnover, changes in VMT between classes, mileage accumulation effects, and registration distributions are unaffected by this command. Emissions Factor Post-Processing Requirements and Procedures There are three limitations of the MOBILE6 model that result in the emissions factors postprocessing requirements for this analysis: MOBILE6 models only one ATP program per run; MOBILE6 assumes a January 1 start for IIM and ATP start year; and MOBILE6 does not model user-specified alternate diesel fuel parameters. For 1990 and 2005 all HGA counties either operated or are to operate two ATPs (see ATP set-ups in Appendix E). The seven non-harris counties ATP and exhaust IIM programs are to start May 1 of the program start years (2003 for the Urban county group, and 2004 for the Rural county group). All HGA counties are to use Texas low-emissions diesel fuel (starting in April 2005). Thus, to produce the final emissions factor inputs to the emissions estimation process, up to three emissions factor post-processing steps were performed per evaluation. To model the full effects of the two-part ATP, emissions factors from three runs were combined. To model the ATP and exhaust IIM programs May 1 start for the seven counties excluding Harris, two emissions factors data sets (each produced from the output of three MOBILE6 runs) were combined. To model the low-emissions diesel effects, no additional MOBILE6 runs were required. An adjustment factor was applied to the NOx emissions factors after the ATP and IIM post-processing steps were completed. The post-processing requirements by evaluation were summarized in Table 17. The IIM and ATP modeling setups and post-processing procedures were developed with information from the IIM SIP (TNRCC, October 2001) and in consultation with the TNRCC Technical Analysis Division. Step 1: Emissions Factor Post-Processing to Combine Effects of Two-Part ATP This procedure was performed for all eight HGA counties modeling ATP for all evaluations except for the 2007 CS (by this date, the earlier model year ATP has phased out). 64

65 To model the credits of both parts of the ATP (ATPl and ATP2 as described in Appendix E), the following emissions factor post-processing calculation (taken from the HGA original 1990 base-year emissions inventory as developed and documented by HGAC, May, 1993) is performed: EFATP I + EF ATP2 - EF NO ATP = EF FINAL Where: EFATPJ EFATP2 EFNOATP EFFJNAL = = = = emissions factor with ATPl credits, emissions factor with ATP2 credits, emissions factor with no ATP credits, emissions factor including estimated credits for both ATPl and ATP2. The RATEADJ6 program (see Appendix B) performed this calculation for each county or county group. The calculation was performed on the second set of runs for the Urban and Rural county categories, to develop required emissions factor input for the May 1 post-processing step (see EFstartYear+I definition in Step 2, below). This second set of runs uses as the ATP and I/M start year inputs, the actual I/M start year plus one. The resulting emissions factors after this step (for each set of runs) include the full effects of the two-part ATP. Proportions of the emissions factors modeled with the "actual" start, and the "start plus one year," are combined as described in Step 2 to model the May 1 start date effects. Step 2: Emissions Factor Post-Processing to Model May I Program Start Effects To model the Urban and Rural county category ATP and exhaust I/M program May 1 start date, a ratio calculation (from the Technical Supplement to the October 2001 I/M SIP) was performed. These calculations were performed on the Urban and Rural emissions factors output from the first post-processing step. There are two MOBILE6 emissions factors sets required for the calculation, the difference between them being the following exhaust I/M and ATP start year input: 1) actual start year, and 2) one year after actual start year. The emissions factors from these two sets are combined as: ((N -1)12+8)XEFAct. StartYear 4 X EFstartYear+l ~~~~~~~~~~~~+ =EFFINAL 12 x N 12 x N Where: N = EF Act. Start Year = EFstartYear+l = EFFINAL = evaluation year - start year emissions factor with actual exhaust I/M and ATP start year, emissions factor with an exhaust I/M and ATP start year one year later, and emissions factor with the estimated May 1 start date of the actual I/M start year. 65

66 Thus, the Urban and Rural county emissions factor ratio formulae for 2005 and 2007 are: May 1 Post-Processing Calculations for 2005: Urban Counties: (0.8333) EFAct. Start Year+ (0.1667) EFstartYear+l = EFFINAL Rural Counties: (0.6667) EFAct.StartYear + (0.3333) EFstartYear+l = EFFINAL May 1 Post-Processing Calculations for 2007: Urban Counties: (0.9167) EFAct.StartYear + (0.0833) EFstartYear+l = EFFINAL Rural Counties: (0.8889) EF Act. Start Year+ (0.1111) EFstart Year+l = EFFINAL The RATEADJ6 program was applied to perform this calculation for each county group. The resulting emissions factors after this step include the combined ATP effects and effects of the exhaust IIM and ATP programs starting on May 1 of the program start years. Step 3: Emissions Factor Post-Processing to Account for Low-Emissions Diesel Effects MOBILE6 does not have an alternate diesel fuel modeling feature. To model the impacts of lowemissions diesel fuel, MOBILE6 diesel vehicle emissions factors were post-processed (with the RATADJV6 program, described in Appendix B). The NOx adjustment factor of was multiplied by all of the diesel-fueled vehicle MOBILE6 NOx emissions factors for all counties for the 2005 and 2007 CS modeling. This adjustment corresponds to a reduction in NOx emissions factors of 5.7 percent. Development of this value is documented in the Eastern Research Group report, Revised SIP 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 Upon completion of this third and last step of the emissions factor post-processing procedures, the emissions factors are ready for input to the IMPSUM6 program to calculate estimated emissions. The modeled emissions factors were provided to TNRCC on CD-ROM. See Appendix A for file names and descriptions. EMISSIONS CALCULATIONS Hourly emissions were calculated by county for each of the seven evaluations using the IMPSUM6 program (Appendix B). With the ozone season weekday 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 emission types on each network link (only the MOBILE6 freeway and arterial emissions factors were used). For each of the seven evaluations, three files were output from the emissions calculations: a summary file of county-level and area total hourly and 24-hour emissions estimates cross classified by vehicle type and road type (including VMT, vehicle hours travelled, VMT weighted speeds, and VMT mix); a tab-delimited version of the emissions summary file, and the file that logged the execution of the emissions calculation programs. These files were previously provided to TNRCC on CD-ROM (see Appendix A). 66

67 Hourly Link Emissions Ozone season weekday emissions were first calculated by hour for each network and intrazonal link (indexed to county and road type) using the following basic inputs: MOBILE6 hourly freeway and arterial emissions factors indexed by speed for 28 vehicle types, developed with POLFAC6; records associating the MOBILE6 freeway emissions factors to the freeway links, and the MOBILE6 arterial emissions factors to the non-freeway links; link data from the assignment results as developed (for each hour) using the PREPIN program including: county number, road type number, VMT on link, operational linkspeed estimate, link node (end point) numbers, and link distance; 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 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 each county or county group. VMT mix correlated to VMT (by functional classification group and hour of day) were multiplied by the fleet total link VMT to produce link VMT estimates by the 28 vehicle types. Emissions factors were then matched with appropriate county link-level VMT (freeway emissions factors to freeway links, and arterial emissions factors to non-freeway links), based on vehicle class and speed. 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 applied, respectively. The link VMT were then multiplied by the emissions factors to produce the link-level emissions estimates. Table 38 show the HGAC TDM functional classes as they are grouped for: 1) the application of MOBILE6 drive-cycle-specific emissions factor, and 2) the application of VMT mix. 67

68 Table38 HGAC TDM Functional Classes by VMT Mix Functional Class Group and MOBILE6 Emissions Factor Drive Cycle MOBILE6 Drive Cycle HGAC TDM Functional Class VMT mix Functional Group Urban Interstate Freeway Arterial Urban Other Freeway Rural Interstate Rural Other Freeway Urban Principal Arterial Urban Other Arterial Rural Principal Arterial Rural Other Arterial Urban Collector Rural Major Collector Rural Collector Local (Centroid Connector) Local (Intrazonal) Freeway Arterial Collector Episode Day Hourly and 24-hour Emissions Summaries For each analysis day, by individual county and for all counties, 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 by individual road type (HGAC network functional classification), individual vehicle type, road type and vehicle type cross classification. VMT, vehicle hours traveled (VHT), VMT-weighted speeds, and other inventory data are included with the emissions summaries. These files (*.LST and a tab delimited version, *.TAB) were previously provided to TNRCC on CD-ROM (see Appendix A). 68

69 APPENDIX A ELECTRONIC SUBMITTAL DATA SET NAMES AND DESCRIPTIONS 69

70

71 ELECTRONIC SUBMITTAL DATA SET NAMES AND DESCRIPTIONS This appendix provides the HGA 1990, 2005, and 2007 ROP on-road mobile source emissions inventory electronic data submittal CD-ROM volume name, and the names and descriptions of the data sets contained on the CD-ROM. TTI provided one CD-ROM containing the emissions inventories data to TNRCC. The CD has two zip files containing: 1) the emissions inventory summary report data files for each of the seven emissions inventories, and 2) the MOBILE6 input files (command and external data) and output files (MOBILE6 emissions factors produced with POLFAC6, RATEADJ6, RATEADJV6). The contents by data category (emissions and emissions factors) are described below. Emissions The emissions inventory data are in the zip file labeled "emissions.zip." There are three files for each of the seven Els, or a total of 21 files. Each of the three file sets contains the following data: IMPSUM6 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; IMPSUM6 hourly "all counties" emissions inventory data summaries; SUMALL6 county-level and "all counties" 24-hour emissions inventory data summaries (one ASCII file with.1st extension); a tab-delimited version of first bullet (one ASCII file with.tab extension); and a log of the emissions estimation program runs (one ASCII file with.log extension). The emissions inventory file names are: HGA90by.* HGA90aby05. * HGA90aby07. * HGA05ccei. * HGA07ccei.* HGA05csei. * HGA07csei. * 1990 base year 1990 base year relative to base year relative to pre-90 control 2007 pre-90 control 2005 control strategy 2007 control strategy Where: * is the extension 1st, tab, and log. Emissions Factors The MOBILE6 input and output files on the CD-ROM are in the ZIP file labeled "efactors.zip." The ZIP file contents are described below: 71

72 Number of Files: There are 145 MOBILE6 input and output files consisting of: MOBILE6 command input files (32); MOBILE6 external data input files (13); final MOBILE6 hourly emissions factor output files (12); interim MOBILE6 hourly emissions factor output files (38); final MOBILE6 daily emissions factor output files (12); interim MOBILE6 daily emissions factor output files (38); emissions factor program run log files (5); and MOBILE6 descriptive output log file (5). File Naming Conventions: HARR: Harris County; Urbarura: the seven Non-Harris counties; Urba: Urban county group (Brazoria, Fort Bend, Galveston, Montgomery); Rura: Rural county group (Chambers, Liberty, Waller); A#: three ATP scenarios, where# is 0, 1, and 2 for No ATP, ATPl, and ATP2; 90: base year; 90aby05: 1990 adjusted base year relative to 2005; 90aby07: 1990 adjusted base year relative to 2007; 05: 2005 control strategy; 07: 2007 control strategy; and I%: two I/Ms for modeling May 1 start, where% is 1, and 2 for start year and start year+ 1. MOBILE6 command input files (32): HARR90_A#.in (3 files), urbarura90.in ( 1 file), HARR90aby05_A#.in (3 files), urbarura90aby05.in (1 file), HARR90aby07 _A#.in (3 files), urbarura90aby07.in (1 file), HARR05_A#.in (3 files), Urba05 _I%A#.in (6 files), Rura05_I%A#.in (6 files), HARR07.in (1 files), Urba07 _I%.in (2 files), and Rura07 _I%.in (2 files). 72

73 MOBILE6 external data input files: HARROS.im (1 I/M file), RURAOS.im (1 I/M file), RURAOSB.im (1 I/M [start yr.+ l] file), URBAOS.im (1 I/M file), URBAOSB.im (1 I/M file for [start yr. + 1]), HARR07.im (1 I/M file), RURA07.im (1 I/M file), RURA07B.im (1 I/M [start yr.+ l] file), URBA07.im (1 I/M file), URBA07B.im (1 I/M file for [start yr. + l]), hgasip.tld (1 regional trip length distributions file), HGA.rgd (1 regional registration distributions file), and HGA.vhr (1 regional VMT BY HOUR file). Final MOBILE6 Hourly Emissions Factors Files (12): HARR90_A.rat (adjusted for full ATP); urbarura90.rat; HARR90aby05_A.rat (adjusted for full ATP); urbarura90aby05.rat; HARR90aby07_A.rat (adjusted for full ATP); urbarura90aby07.rat; HARROS_A_led.rat (adjusted for full ATP and LED); Urba05 _IA_led.rat (adjusted for May 1 I/Mand ATP, full ATP, and LED); Rura05_IA_led.rat (adjusted for May 1 I/Mand ATP, full ATP, and LED); HARR07_led.rat (adjusted for LED); Urba07 _!_led.rat (adjusted for May 1 I/Mand ATP, and LED); and Rura07_I_led.rat (adjusted for May 1 I/Mand ATP, and LED). Interim MOBILE6 Hourly Emissions Factors Files (38): HARR90_A#.rat (3 files for ATP adjustment); HARR90aby05_A#.in (3 files for ATP adjustment); HARR90aby07_A#.in (3 files for ATP adjustment); HARROS_A#.rat (3 files for ATP adjustment); HARROS_A.rat (1 file adjusted for ATP, needs LED adjustment); Urba05_1%A#.rat (6 files for I/M, ATP, and LED adjustment); Urba05_1%A.rat (2 files adjusted for ATP, needs I/Mand LED adjustment); Urba05_IA.rat (1 file adjusted for ATP and I/M, needs LED adjustment); Rura05_1%A#.rat (6 files for I/M, ATP, and LED adjustment); Rura05_1%A.rat (2 files adjusted for ATP, needs I/Mand LED adjustment); Rura05_IA.rat (1 file adjusted for ATP and I/M, needs LED adjustment); HARR07.rat (1 file needs LED adjustment); 73

74 Urba07 _I%.rat (2 files needs I/Mand LED adjustment); Urba07 _I.rat (1 file needs LED adjustment); Rura07 _I%.rat (2 files needs I/Mand LED adjustment); and Rura07 _!%.rat (1 file needs LED adjustment). Final (12) and Interim (38) MOBILE6 Daily Emissions Factors Files (12): The set of 24-hour average (i.e., daily) emissions factor files has the same names as the hourly files, except with ".rtd" extension. The "daily all roads" emissions factors in the.rtd files are invalid. However, the individual MOBILE6 road type (drive cycle) emissions factors are valid. Emissions Factor Log (*.LOG) and MOBILE6 Descriptive Output (*.LST) files (5 each): The log files are a record of the emissions factor program (POLFAC6, RATEADJ6, and RATEADJV6) runs (one ASCII file with.log extension). The MOBILE6 descriptive output is a record of the MOBILE6 descriptive output corresponding to each POLFAC6 run. The value of this output is in the listings of the MOBILE6 inputs used (the emissions factors in the descriptive output are "daily all road types" emissions factors, however, which are not valid due to the use of MOBILE6 default VMT BY FACILITY input). HG90by.* HG90aby05.* HG90aby07.* HG05cs.* HG07cs.* 74

75 APPENDIXB EMISSIONS ESTIMATION PROGRAMS 75

76

77 TTI EMISSIONS ESTIMATION PROGRAMS The following is a summary of the series of programs developed by TTI for developing linkbased, time-of-day, on-road mobile source emissions estimates for air quality analyses. These programs produce emissions factors with the latest version of EPA's MOBILE emissions factor model, and apply them to travel model-based activity estimates to calculate emissions at user-specified temporal and spatial scales. The location of emissions by grid, or travel network link coordinates, may also be specified. The emissions estimation programs are: PREPIN, POLFAC6, RATEADJ6, RATEADJV6, IMPSUM6, and SUMALL6. PREPIN prepares activity input, POLFAC6 prepares emissions factor input, the RA TEADJ programs make special adjustments to emissions factors when required, IMPSUM6 calculates emissions by time period, and SUMALL6 summarizes emissions at various levels by 24-hour period. PREP IN The PREPIN program post-processes travel model output to produce time-of-day-specific, onroad vehicle fleet, link VMT and speed estimates for emissions inventory applications. The PREPIN 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, PREPIN reads a travel demand model traffic assignment data set from a directional four period time-of-day assignment (another common assignment read by PREPIN is the nondirectional or directional 24-hour assignment). PREPIN 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-of-day 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. POLFAC6 The POLFAC6 program is used to apply the EPA's MOBILE6 program to calculate the on-road mobile emissions factors. The MOBILE6 emissions factors may be produced for each of 15 pollutant-specific emissions types (i.e., the composite, exhaust running, and exhaust start for VOC, CO, and NOx rates plus the six sub-component VOC evaporative rates), 28 vehicle types, four MOBILE6 functional classifications (or drive cycles, i.e., Freeway, Arterial/Collector, Local, and Ramp), 14 speeds (i.e., 2.5 mph, and 5 mph through 65 mph at 5 mph increments for Freeway and Arterial functional classifications-mobile6 local and ramp functional classification rates are single speed only, 12.9 mph, and 34.6 mph, respectively), and each of the 24 hours of the day. These emissions factors are tabulated individually by county and analysis day for the evaluation year. These hourly emissions factors are output to an ASCII file for 77

78 subsequent input to the IMPSUM6 program. The IMPSUM6 program is then used to apply the hourly emissions factors to hourly VMT estimates by link. (POLFAC6 also optionally produces a set of daily emissions factors.) RATEADJ6 RATEADJ6 is a special utility program that produces a new set of emissions factors by linearly combining the emissions factors from multiple applications of POLFAC6. There is one set of linear factors. Each factor is applied to all emissions rates in a single data set. A practical application of the RA TEADJ program is the combining of two sets of emissions factors, where each set has different control program credits, into one set including the combined credits. For example, this program is commonly used to combine different Anti-Tampering Program (ATP) credits from two separate POLFAC6 runs into one set of emissions factors that includes the credits for both ATPs. RATEADJV6 RATEADJV6 is a special utility program that produces a new set of emissions factors by linearly combining the emissions factors from multiple applications of POLFAC6 and/or RATEADJ6. There are 420 linear equations; one for each of 15 emissions types and 28 vehicle types. A practical application of RATEADJV6 is the application of emissions factor credits by individual vehicle class and/or individual pollutant. For example, for analysis requiring the effects of the Texas Low Emissions Diesel Fuel Program in MOBILE6 emissions factors, RATEADJV6 is used to apply reduction factors to only the NOx emissions factors of all diesel-fueled vehicle classes. IMPSUM6 The IMPSUM6 program applies the emissions factors from POLFAC6 (or from one of the RATEADJ programs, when used) and VMT mixes (fractions of fleet VMT attributable to each vehicle classification in the study) to the time-of-day fleet VMT and speed estimates to calculate emissions by the specified time periods. The five primary inputs to IMPSUM6 are: MOBILE6 emissions factors developed with POLFAC6 (or a RATEADJ6, if used); abbreviated assignment results by link (for the subject time period), developed using the PREPIN program. (The PREPIN program allows the user to estimate the VMT and speed on each link by time period.) For each link, the following information is input to IMPSUM6: county number, roadway type number, VMT on link, operational link-speed estimate, and link distance; VMT mix by time period, county and roadway type; X-Y coordinates; and 78

79 data records associating the MOBILE6 drive cycle (Freeway, Arterial, Local, Ramp) emissions factors (or percentages thereof) to specific travel model functional classifications. These MOBILE6 drive cycle emissions factor percentages (valid from zero to 100) must sum to 100 percent for each travel model functional classification. Using these input data, the VMT for each link is stratified by MOBILE6 drive cycle and the 28 vehicle types. The MOBILE6 emissions factors matched to link-vmt by drive cycle and vehicle type are interpolated (for the link speed that falls between the 14 MOBILE6 speeds; see the MOBILE6 interpolation methodology below) and multiplied by the link VMT to estimate the mobile source emissions for that link. Emissions factors for 65 mph are used for links with speeds greater than 65 mph and emissions factors for 2.5 mph are used for links with speeds lower than 2.5 mph. The emissions for the county and emissions type are reported by both roadway type and vehicle type (i.e., cross classified by roadway type and vehicle type) for each of the subject time periods. A data set is produced for subsequent input to the SUMALL6 program. X-Y coordinates are optionally used to produce gridded emissions. Also, link emissions may be written by county. The link emissions are for 15 emissions types and 28 vehicle types and include the "A" node and "B" node (endpoints) of the links for which X-Y coordinates may be obtained. Example Emissions Factor Interpolation To calculate emissions factors for average operational link speeds that fall between two of the 14 MOBILE6 speed bin speeds, MOBILE6 interpolates each emissions factor using a factor developed from the inverse link speed and the inverse high and low bounding speed bin speeds (Section 5.3.4, MOBILE6 User's Guide, January 2002). Using the MOBILE6 emissions factors tabulated by the 14 speeds, the IMPSUM6 program uses the MOBILE6 method to interpolate emissions factors as shown in the following example. This example interpolates an emissions factor corresponding to an average link speed of 41.2 mph. A tab-delimited output is optionally produced. This output has all 28 vehicle types (or eight vehicle types in the compressed format) across a single output line. Each field in the output is separated by a tab character. The interpolated emissions factor (EF1nterp) is expressed as: = EFLowSpeed - F AClnterp X (EFLowSpeed - EFHighSpeed ) Where: EFLowSpeed EFHighSpeect = emission factor (EF) corresponding to tabulated speed below the average link speed, = EF corresponding to tabulated speed above the average link speed, and 79

80 FAC1nterp = ( Spe:d,,,,. Spe:d1~ )/ ( Spe~dmgh - Spe:d1~) Given that: EFLowSpeed = g/mi, EFHighSpeed = g/mi, Speed 1 nk = 41.2mph, Speed 10 w = 40mph, Speedhigh = 45 mph. EF1nterp = g/mi - ( ) x ( g/mi g/mi) = g/mi SUMALL6 The SUMALL6 program is used to sum the emissions estimates for the time-of-day periods (e.g., 24 periods in the case of hourly analyses) to develop 24-hour emissions estimates. The emissions by pollutant type are reported by roadway type and 28 vehicle types (or optionally condensed to eight vehicle types). A tab-delimited output is optionally produced. This output includes all 28 vehicle types (or eight vehicle types in the compressed format) across a single output line. Each field in the output is separated by a tab character. The overall emissions estimate process flow is shown in the diagram below. 80

81 Travel Model 8 s.! ~-.e e, 8! 8 Emissions Estimate v_m_t_m_i_x_, 81

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83 APPENDIXC HOURLY VOLUME FACTORS 83

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85 Weekday HGA Hourly Volume Factors for 24-hour Assignment Freeways, Interstate Hour 06:00 07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 00:00 01:00 02:00 03:00 04:00 05:00 CBD and Urban Urban Fringe Suburban Rural

86 Weekday HGA Hourly Volume Factors for 24-hour Assignment Arterials, Major Collectors Hour 06:00 07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 00:00 01:00 02:00 03:00 04:00 05:00 CBD and Urban Urban Fringe Suburban Rural

87 Weekday HGA Hourly Volume Factors for 24-hour Assignment Collectors, Locals --.!!r 06:00 07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 00:00 01:00 02:00 03:00 04:00 05:00 CBD and Urban Urban Fringe Suburban Rural

88 Weekday HGA Hourly Volume Factors for Four-Period Time-of-Day Assignments Freeways, Interstate Hour CBD and Urban Urban Fringe Suburban Rural ~ C'!I 06: ~ ~ 07: ~ < 08: : : ~ 11: 't:l 't:l 12: : 13: ~ ~ ~ 14: : : : f 18: : : : : : Q e ~ : : : : : :