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Air Quality Research and Contract Reports: On-Road Vehicles

Reports related to air pollutant emissions, fuels, and activity of on-road vehicles written by contractors for the TCEQ.

Reports from Air Quality Research and Contract Projects related to on-road vehicles are posted here as PDF files, unless otherwise specified. Some reports have companion data files in various formats.

For comments and questions regarding these reports, please e-mail us at amda@tceq.texas.gov, put "On-Road Vehicles Contract Report Inquiry" in the subject line, and include the web address of the report.

2023 Summer Fuel Field Study - This report and data files (zipped, 12 MB) by the Texas A&M Transportation Institute details the 2023 study of gasoline and diesel fuel properties from samples collected at 91 fueling stations throughout Texas. Fuel properties examined include sulfur content, volatility, and chemical composition. The analyses of the fuel samples are expected to improve emission estimates from Texas vehicles in air quality planning and modeling. (February 2024)

MOVES3 On-Road Trend Emissions Inventories for 1990 and 1999 through 2060 - This report developed by the Texas A&M Transportation Institute (TTI) provides updated on-road trend emissions inventories for criteria air pollutants (CAPs), CAP precursors, and hazardous air pollutants (HAPs) to support on-going air quality planning activities with the EPA released MOVES3 model. This new set of trends inventories helps characterize the transition to MOVES3, respond to data requests, assess past performance, and determine future requirements. (October 2023)

Houston-Galveston-Brazoria On-Road Emissions Inventory for 2026 - This report, provided by the Texas A&M Texas Transportation Institute (TTI), details the development of Houston area on-road emissions inventories for 2026 using version 3 of the Motor Vehicle Emission Simulator (MOVES3). (June 2022)

Texas Vehicle Emissions Inspection and Maintenance Program Fee Analysis - Eastern Research Group, Inc (ERG) conducted an analysis evaluating the adequacy of the vehicle emissions inspection fee in the Houston-Galveston-Brazoria (HGB), Dallas-Fort Worth (DFW), El Paso, and Austin-Round Rock (ARR) Vehicle Emissions Inspection and Maintenance (I/M) program areas. The report contains the ERG's analysis. (June 2022)

Texas Vehicle Emissions Inspection and Maintenance Program Evaluation, 2022 Report - Eastern Research Group, Inc (ERG) evaluated the enhanced Vehicle Emissions Inspection and Maintenance (I/M) program operating in the Dallas-Fort Worth (DFW) and the Houston-Galveston-Brazoria (HGB) areas. The report contains the results of the evaluation. (June 2022)

Operating Mode Emissions Estimation Methodology Development and Application – This report, prepared by the Texas A&M Transportation Institute (TTI), describes the development and use of a method to separate on-road mobile source evaporative process emissions into operating modes, using the EPA Motor Vehicle Emissions Simulator (MOVES) model . (September 2022)

Statewide On-road Mobile Air Emissions Reporting Requirements and Hazardous Air Pollutants Emissions Inventory – This report, provided by the Texas A&M Transportation Institute, documents the development of Texas on-road mobile source emissions by county for 2020 using version 3 of the Motor Vehicle Emission Simulator. (MOVES3 ). The vehicle emissions estimates of criteria air pollutants, their precursors, and hazardous air pollutants (HAPs) will be used for the Air Emissions Reporting Requirements (AERR), the comprehensive three-year cycle National Emissions Inventory (NEI), and Texas air quality planning efforts. (April 2022)

Houston-Galveston-Brazoria On-Road Reasonable Further Progress (RFP) Emissions Inventories – This report, provided by the Texas A&M Texas Transportation Institute (TTI), details the development of Houston area on-road RFP emissions inventories for the years 2011-2027 using version 3 of the Motor Vehicle Emission Simulator (MOVES3 ). (June 2021)

Statewide Non-Link On-Road Emissions Inventories – This report, provided by the Texas A&M Texas Transportation Institute (TTI), details the development of statewide non-link on-road emissions inventories for 2019, 2023, and 2026 using version 3 of the Motor Vehicle Emission Simulator (MOVES3 ). Appendix A describes emission inventory utility tools used to produce the emission inventories. Appendix B provides a description of the deliverable files. Appendix C is an Excel spreadsheet of the vehicle miles traveled by vehicle and fuel type in each Texas Department of Transportation District. (June 2021)

Houston-Galveston-Brazoria On-Road Emissions Inventories – This report, provided by the Texas A&M Texas Transportation Institute (TTI), details the development of Houston area on-road emissions inventories for 2019 and 2023 using version 3 of the Motor Vehicle Emission Simulator (MOVES3 ). Appendix A describes emission inventory utility tools used to produce the emission inventories. Appendix B provides a description of the deliverable files. (June 2021)

San Antonio On-Road Emissions Inventories – This report, provided by the Texas A&M Texas Transportation Institute (TTI), details the development of San Antonio on-road emissions inventories for 2019 and 2023 using version 3 of the Motor Vehicle Emission Simulator (MOVES3 ). Appendix A describes emission inventory utility tools used to produce the emission inventories. Appendix B provides a description of the deliverable files. (June 2021)

On-Road Emission Quality Assurance Tool II – This report, provided by the Texas A&M Texas Transportation Institute (TTI), details the development of a quality assurance (QA)/quality control (QC) utility tool for TCEQ on-road mobile staff to quality assure the United States Environmental Protection Agency (EPA) Motor Vehicle Emission Simulator (MOVES) on-road input and output data and parameters. The tool is compatible with MOVES2014a and MOVES2014b and includes a graphical user interface (GUI) to allow a user to complete input and output database QA more efficiently. (June 2020)

2020 Summer Fuel Field Study – This report and data files (zipped, 8 MB) , provided by Eastern Research Group, Inc. (ERG), document the data collection and analysis of samples of gasoline and diesel fuel collected from retail stations across Texas during the Summer of 2020. The data from this study are used to develop the physical properties and speciation profiles of gasoline and diesel fuel that are used in the development of mobile source State Implementation Plans (SIPs), emissions inventories, trend analysis, and control strategy analysis. (September 2020)

Statewide 2017 On-Road Mobile Source Annual, Summer Weekday, and Winter Workday Emissions Inventories: Austin Area (revised, Oct 9, 2019), Beaumont-Port Arthur Area , Dallas Fort-Worth Area , El Paso Area , Houston-Galveston-Brazoria Area , San Antonio Area , Tyler-Longview-Marshall Area , and other 214 Counties - These reports, provided by Texas Transportation Institute, document the on-road mobile portion of the 2017 evaluation year emissions inventories by geographic areas for the State of Texas under the Air Emissions Reporting Requirements (AERR) and the EPA comprehensive three-year cycle National Emissions Inventory (NEI). Annual, summer weekday, and winter work weekday emissions inventory estimates of criteria air pollutants (CAPs), CAP precursors, and hazardous air pollutants (HAPs) are developed by area counties and summarized in each document. (August 2019)

Heavy-Duty Vehicle Idle Activity Study - This report, provided by Texas Transportation Institute, documents data collection, data analysis and resulting long term idle hours and auxiliary power unit (APU) hours for heavy duty vehicles (HDV) operating in Texas. The most recent EPA emission factor model, the MOVES model, now includes the emissions due to HDV idling and use of APUs in on-road inventories as a separate source category of emissions. The results in this report can be used to update and refine the default information in MOVES. The Texas HDV idle and APU hours database is available for FTP download . (July 2019, revised December 2019)

2017 Summer Fuel Field Study - This report and data files (zipped) , provided by Eastern Research Group, Inc. (ERG), document the data collection and analysis of samples of gasoline and diesel fuel collected from retail stations across Texas during the Summer of 2017. The data from this study are used to develop the physical properties and speciation profiles of gasoline and diesel fuel that are used in the development of mobile source episodic state implementation plans (SIPs), Periodic, Rate of Progress, and toxic emissions inventories, trend analysis, and control strategy analysis. (August 2017)

Rail Yard Activity Study: Development of Truck Activity and On-Road Emissions Estimates for Four Texas Intermodal Facilities - This report, provided by Texas A&M Transportation Institute (TTI), provides 2011, 2014, and 2017 provisional on-road mobile emissions inventory estimates for the truck activity at the Tower 55 rail yard in DFW and the rail yard adjacent to the Port of Houston marine port. The study used existing data sources to estimate the off-network activity levels, operating mode fractions, and fleet characteristics. The activity and fleet information was used in conjunction with emission rates from the Motor Vehicle Emissions Simulator (MOVES) to develop emission estimates at each site. (April 2017)

Development of On-Road Emissions Quality Assurance Tool - This report, provided by the Texas A&M Transportation Institute (TTI), documents the development and user guide information for the electronic quality assurance (QA)/quality control (QC) utility tool. This tool was developed for use with on-road mobile source emissions inventories developed using the United States Environmental Protection Agency (EPA) Motor Vehicle Emission Simulator (MOVES). The utility tool: performs a QA of on-road MOVES inventory mode inputs and outputs; identifies formatting and data errors in the inputs and outputs; and, provides a report summary of any errors identified. The QA utility tool includes a graphical user interface (GUI) to allow a user to complete input and output database QA more efficiently. Contact the Emissions Assessment Section at 512-239-1046 to obtain a link to the utility tool. (December 2016)

DFW On-road Mobile 2014 Air Emissions Reporting Requirements and Hazardous Air Pollutants Inventory - This report, provided by the North Central Texas Council of Governments (NCTCOG), documents the on-road mobile portion of the 2014 evaluation year emissions inventories in the Dallas-Fort Worth area for the State of Texas under the Air Emissions Reporting Requirements (AERR) and the EPA comprehensive three-year cycle National Emissions Inventory (NEI). Annual, summer weekday, and winter work weekday emissions inventory estimates of criteria air pollutants (CAPs), CAP precursors, and hazardous air pollutants (HAPs) are developed by area counties and summarized in this document. (November 2015)

Statewide (excluding the 12 Counties in Dallas-Fort Worth) 2014 On-Road Mobile SourceAnnual, Summer Weekday, and Winter Workday Emissions Inventories: Austin Area , Beaumont-Port Arthur Area , El Paso Area , HGB Area , San Antonio Area , Northeast Texas Area , and other 214 Counties - These reports, provided by Texas Transportation Institute, document the on-road mobile portion of the 2014 evaluation year emissions inventories by geographic areas for the State of Texas under the Air Emissions Reporting Requirements (AERR) and the EPA comprehensive three-year cycle National Emissions Inventory (NEI). Annual, summer weekday, and winter work weekday emissions inventory estimates of criteria air pollutants (CAPs), CAP precursors, and hazardous air pollutants (HAPs) are developed by area counties and summarized in each document. (August-November 2015)

MOVES2014 On-road Trend Emissions Inventories for 1990 to 2050 - This report and chart document , provided by the Texas A&M Transportation Institute (TTI), provide updated on-road trend emissions inventories for criteria air pollutants (CAPs), CAP precursors, and hazardous air pollutants (HAPs) to support on-going air quality planning activities with the new EPA released MOVES2014 model. This new set of trends inventories helps: characterize the transition to MOVES2014; respond to data requests; assess past performance; and determine future requirements. (August 2015)

2011 Summer Fuel Field Study (revised) - This report and data files (zipped) , developed through a work order with Eastern Research Group, Inc. (ERG), documents the data collection and analysis of samples of gasoline and diesel fuel collected from retail stations across Texas during the Summer of 2011. The data from this study are used to develop the physical properties and speciation profiles of gasoline and diesel fuel that are used in the development of mobile source episodic state implementation plans (SIPs), Periodic, Rate of Progress, and toxic emissions inventories, trend analysis, and control strategy analysis. These data are also used in photochemical air quality dispersion modeling, conformity and other sensitivity analysis. (August 2011/Revised March 2015)

2014 Summer Fuel Field Study - This report and data files (zipped) , developed through a work order with Eastern Research Group, Inc. (ERG), documents the data collection and analysis of samples of gasoline and diesel fuel collected from retail stations across Texas during the Summer of 2014. The data from this study are used to develop the physical properties and speciation profiles of gasoline and diesel fuel that are used in the development of mobile source episodic state implementation plans (SIPs), Periodic, Rate of Progress, and toxic emissions inventories, trend analysis, and control strategy analysis. (August 2014/Revised January 2015)

Development of Oil and Gas Mobile Source Inventory in the Barnett Shale in the 12-County Dallas-Fort Worth Area - This report, developed through a work order with North Central Texas Council of Government (NCTCOG), documents the study to develop emissions inventories associated with Barnett Shale VMT and long-team idling of heavy duty diesel vehicles activities using MOVES based in the 12-county NCTCOG Metropolitan Planning Area (MPA), Collin, Dallas, Denton, Ellis, Hood, Hunt, Johnson, Kaufman, Parker, Rockwall, Tarrant, and Wise. (August 2012)

Characterization of Vehicle Activity and Emissions from Heavy-Duty Diesel Vehicles in Texas - This report, developed through a work order with Texas Transportation Institute (TTI), documents the estimation of vehicle miles traveled (VMT) proportions of local and pass-through heavy-duty diesel vehicles (HDDVs) throughout Texas with a focus on current and near non-attainment areas. This was achieved by comparing local and non-local VMT produced by HDDVs. TTI then produced emissions estimates using the VMT proportions and emission rates based upon the latest available Highway Performance Monitoring System based data and the MOVES model. The analysis years for this study are 2008–2030. (August 2011)

Methodologies for Conversion of Data Sets for MOVES Model Compatibility - This report was developed by the Texas Transportation Institute (TTI) to investigate methods for utilizing existing transportation data sets to be compatible with the Motor Vehicle Emissions Simulator (MOVES) model from EPA. MOVES categorizes the on-road fleet into nine fuel types and thirteen "source use types" (SUTs). Recommended are made for querying the vehicle registration database from the Texas Department of Transportation (TxDOT) so that the final output can be compatible with the SUT age distribution format needed for MOVES. Recommendations are also made for using existing vehicle classification counts available from TxDOT for allocation of vehicle miles traveled (VMT) estimates by SUT. (August 2009)

2008 On-Road, Mobile Source Statewide Air Toxics Annual Emissions Inventory - This report was developed through a work order with the Texas Transportation Institute (TTI), to provide a 2008 Mobile Source Air Toxics (MSAT) in support of the Federal Clean Air Act Amendment (CAAA) requirement. MSAT is prepared for all 254 Texas Counties. This Toxics inventory estimates annual emissions, for various volatile organic compound (VOC) and metals, as well as diesel particulate matter and diesel exhaust organic gases. (June 2009)

Estimates of Emission Reductions from Performing OBDII Tests on 1997 and Newer Diesel Vehicles - This study was performed to obtain estimates of the emissions benefits that could be achieved from requiring annual emissions inspections on diesel-fueled vehicles in counties currently participating in I/M or planning to participate in the future. (October 2008)

2008 Summer Fuel Field Study - This report and data files (zipped) , developed through a work order with Eastern Research Group, Inc. (ERG), documents the data collection and analysis of samples of gasoline and diesel fuel collected from retail stations across Texas during the Summer of 2008. The data from this study are used to develop the physical properties and speciation profiles of gasoline and diesel fuel that are used in the development of mobile source episodic state implementation plans (SIPs), Periodic, Rate of Progress, and toxic emissions inventories, trend analysis, and control strategy analysis. These data are also used in photochemical air quality dispersion modeling, conformity and other sensitivity analysis. (August 2008)

Preliminary Review of Data Sources To Identify Portion of Heavy-Duty Vehicle Activity in Texas Metropolitan Areas from Long-Haul Pass-Through Trucks - This report, provided by the Texas Transportation Institute (TTI), reviewes the different methodologies that could be employed to separate the "eighteen-wheeler" heavy-duty truck activity into both "short-haul" and "long-haul" components. The report both summarizes and compares the various advantages and disadvantages of the different data collection and survey approaches. No new data were collected for this study, but a sample of global positioning system (GPS) data was obtained for in-transit trucks to evaluate the feasibility of using existing electronic tracking information for identification of "pass-through" trucks. Using GPS for this purpose shows long-term promise, but current obstacles exist related to widespread data availability and the ability to satisfactorily post-process the information gathered. (August 2008)

2007 Summer Fuel Field Study - This report, developed through a work order with Eastern Research Group, Inc. (ERG), documents the data collection and analysis of samples of gasoline and diesel fuel collected from retail stations across Texas that is used to develop physical properties and speciation profiles of gasoline and diesel fuel used in the development of mobile source episodic state implementation plans (SIPs), Periodic, Rate of Progress, and toxic emissions inventories, trend analysis, and control strategy analysis. These data are also used in photochemical air quality dispersion modeling, conformity and other sensitivity analysis. (August 2007)

Link Speed Estimation Improvements for MOBILE6 Modeling Using TranStar Data - This report and its supplemental appendices, provided by the Texas Transportation Institute (TTI), document improvements for MOBILE6 modeling using TranStar data. TranStar is a consortium of four local government agencies responsible for transportation management in the Houston metropolitan area: Texas Department of Transportation (TxDOT), Harris County, Metropolitan Transit Authority of Harris County (METRO), and the City of Houston. The two types of historical TranStar data are identified as Automated Vehicle Identification (AVI) and Wavetronix. The larger AVI data set contains roadway segment distance and travel time data to estimate average operating speed. Variations in average operating speed by roadway segment from the AVI data set were compared for various episodes in both 2005 and 2006. The smaller Wavetronix data set is radar-based and includes traffic volume as well as speed. The 2005 and 2006 Wavetronix data were analyzed to verify the performance of speed model applications for the Houston travel network. (August 2007)

Development and Production of VMT Profiles for Non-School, Memorial Day, and Labor Day Weekends - This report, provided by the Texas Transportation Institute (TTI), documents analysis of Automatic Traffic Recorder (ATR) data collected by the Texas Department of Transportation (TxDOT) from 2000-2006 for these Texas areas: Austin, Beaumont/Port Arthur, Dallas/Fort Worth, El Paso, Houston/Galveston/Brazoria, San Antonio, Tyler/Longview, "urban" grouping for all areas referenced above, "rural" grouping for all areas not referenced above, and an aggregate Statewide summary for all 254 Texas Counties. For each area, ATR data were used to determine both the daily and hourly differences in vehicle miles traveled (VMT) distributions between "in-school" and "non-school" periods. In addition, both Memorial Day and Labor Day holiday weekends were compared to "regular" weekends to determine differences in both daily and hourly VMT distributions. (August 2007)

DFW Diesel Fraction Study - This report, developed through a work order with North Central Texas Council of Government (NCTCOG), documents the emission sensitivity of the diesel fraction and vehicle age distribution for diesel vehicle classes in MOBILE modeling, in the Dallas Forth worth nonattainment area. It also addresses how to reduce the variation in emissions by including interaction between the counties that account for commuter flow and regional distribution of heavy-duty vehicle travel. This report has two additional MS Excel files: Appendix B - Diesel Fraction and Appendix C - Vehicle Registration Distribution (August 2005).

TxLED VMT Estimation Project - This report, developed through a work order with Cambridge Systematics, Inc., documents development of Vehicle Miles of Travel (VMT) estimates for local and non-local trucks. This information is useful for determining the rule effectiveness for control strategies that will effect local trucks but not non-local trucks. The study included the DFW and HGB ozone nonattainment areas. (August 2004)

Heavy-duty Diesel Vehicle (HDDV) Idling Activity and Emissions Study: Phase 2 - Statewide Data Collection and Emission Inventory Development - Heavy-duty diesel vehicle (HDDV) emissions contribute to the production of NOx, a precursor of ozone formation. One source of HDDV NOx is the emissions produced during long term idling (more than 15 minutes). An emissions inventory for HDDV idling requires an accurate estimate of extended diesel truck idling activity. At the time of this report, there were no studies that comprehensively quantified the extent of diesel truck idling. The TCEQ contracted with Eastern Research Group (ERG) to develop a statewide On-Road Heavy-Duty Vehicle (HDV) Extended Idling Activity Database and Emissions Inventory for all counties in Texas. ERG was tasked with characterizing NOx emissions from heavy-duty trucks idling for more than 15 consecutive minutes at a time, for the following source generator categories: truck stops and travel plazas; state-maintained rest areas and travel centers; commercial marine ports; airports; and, inter-modal rail yards. (August 2004)

Assess Currently Available Houston Ship Channel Area VMT Mix Data and Identify Additional Data Required - This report, developed through a work order with TTI, reviewed the activities of HDDV8b in the Houston Ship Channel areas as it relates to the Harris county area. The current TxDOT vehicle classification data for the Houston ship channel area was reviewed and the VMT mix for the ship channel area was calculated using the currently available vehicle classification data. The procedures used and the result obtained are documented in this report. (August 2004)

Heavy-duty Diesel Vehicle (HDDV) Idling Activity and Emissions Study: Phase 1 - Study Design and Estimation of Magnitude of the Problem - This report, developed through a work order with Texas Transportation Institute (TTI), documents data collection and analysis done to develop a rough estimate of the activity and related emissions associated with extended idling by HDDVs in Texas, and the development of a study design for Phase 2 of the project, to accurately quantify extended truck idling activity and emissions. Phase 2 of the idle activity and emission inventory is documented in a separate report. (August 2003)

Evaluation of MOBILE for Application to Houston, TX - This report, developed through a work order with Environ International Corp, provides the result of evaluating MOBILE by comparing ratios of species in emissions inventories prepared using MOBILE with corresponding ratios in ambient data. In the study Environ compared estimates of emission ratios of non-methane hydrocarbon (NMHC) and carbon monoxide (CO) to nitrogen oxides (NOx) in a detailed, MOBILE6-based inventory that was developed for Houston with NMHC/NOx and CO/NOx ratios observed at several Houston area monitoring sites for the 1999-2001 summer ozone season. (November 2002)

2007 On-Road Mobile Source Episode Specific Emissions Inventories for the Beaumont-Port Arthur Ozone Nonattainment Area - This report, developed through a work order with TTI, summarizes the development of link-based on-road mobile source inventories utilizing MOBILE6 in the Beaumont-Port Arthur nonattainment area for the 2007 future case projection of the August 22 - September 1, 2000 ozone episode. A discussion of the MOBILE6 55 mph speed limit benefits for 2007 is included in the report. (August 2002)

2000 On-Road Mobile Source Episode Specific Emissions Inventories for the Beaumont-Port Arthur Ozone Nonattainment Area - This report, developed through a work order with TTI, summarizes the development of link-based on-road mobile source inventories utilizing MOBILE6 in the Beaumont-Port Arthur nonattainment area from August 22 - September 1, 2000. (August 2002)

2007 On-Road Mobile Source Episode Specific Emissions Inventories for the Houston-Galveston Ozone Nonattainment Area - This report, developed through a work order with TTI, summarizes the development of link-based on-road mobile source inventories utilizing MOBILE6 in the 8-County Houston/Galveston nonattainment area for the 2007 future case projection of the August 22 - September 1, 2000 ozone episode. A discussion of the MOBILE6 55 mph speed limit benefits for 2007 is included in the report. (March 2002)

Houston Area School Year VMT Estimates and Adjustments for Episode Analyses - This report, developed through a work order with TTI, documents development of VMT adjustment factors and VMT estimates for school and non-school ozone exceedence episode days of 1998, 2000, and 2007 for the Houston-Galveston Ozone Nonattainment Area. (August 2002)

Supplemental Vehicle Classification Data Collection and Analysis for the Houston Area - This report, developed through a work order with TTI, documents the activities associated with deployment of vehicle classification count data collectors to obtain updated weekday, Friday, Saturday, and Sunday field data for the Houston-Galveston ozone nonattainment area. This phase of the project includes data collection in July and August of 2002. Some analysis of the data has been completed and is included in this report. However, since September data is required to complete this project, and since the TCEQ fiscal year ends in August, complete data collection and updated vehicle miles of travel (VMT) mixes were developed when the project was completed under a second phase beginning September 2002. (August 2002)

2000 On-Road Mobile Source Episode Specific Emissions Inventories for the Houston-Galveston Ozone Nonattainment Area - This report, developed through a work order with TTI, summarizes the development of link-based on-road mobile source inventories utilizing MOBILE6 in the 8-County Houston/Galveston nonattainment area from August 22 - September 1, 2000. (March 2002)

Area and Mobile Source Emission Inventory Technical Support Project: 1990 - 2010 Emission Inventory Trends and Projections - This report, developed through a work order with Environ International, documents development of an update to the 1999 area, nOn-Road and biogenic emission inventories and development of 1990 to 2010 trend/projected inventories for On-Road, nOn-Road and area sources. All the inventories include VOCs, NOx, CO, SO2, and particulate matter (both PM10 and PM 2.5). The trend inventories include development of 1990 to 2010 annual and ozone season day emission trends and projections for all area, on-road mobile, and nOn-Road mobile sources. (August 2001)

TexAQS On-Road Mobile Source Emissions Estimation - This report, developed through a work order with TTI, summarizes the development of link-based on-road mobile source inventories utilizing MOBILE5b in the 8-County Houston/Galveston nonattainment area from August 15 - September 7, 2000. (August 2001)

1990 - 2010 On-Road Emission Trends Inventory Support for ENVIRON - This Technical Note, developed through a work order with TTI, documents development of On-Road mobile activity inputs required for inventory development, for analysis year 1990 to 2010, for each Texas county. This work was done to support development of MOBILE6 (pre-release version) based On-Road mobile trend emission inventories for every Texas county from 1990 to 2010. The activity measures documented include: annual VMT, seasonal adjustment factors, summer VMT, winter VMT and VMT mix. The emission inventories are available in a separate report. (July 2001)

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