2007 On-Road Mobile Source Emissions Inventories For 243 Texas Counties In the Houston-Galveston Ozone Modeling Domain (TTI-2002-6)

This Technical Note documents the methods the Texas Transportation Institute (TTI) used to develop the Statewide (i.e., 243 of the 254 Texas counties, but referred to in this document as Statewide) August 2007 day-of-week on-road mobile source emissions estimates. These emissions forecasts are developed for input to the Houston?Galveston photochemical grid model. (The August 2000 base-case Statewide on-road mobile emissions estimates documentation, also produced under this task, is provided in a separate Technical Note.) The 243 counties of this analysis include all Texas counties except for the 11 HoustonGalveston (HGA) (Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery, and Waller) and Beaumont?Port Arthur (BPA) (Hardin, Jefferson, and Orange) ozone nonattaiment counties. (The 2007 HGA and BPA county emissions estimates were produced under a different task.) Climate inputs used in the Statewide emissions forecasts are from the base-year ozone episode period August 22 through September 1, 2000. Emissions estimates are developed based on August activity characteristic of four day types: Weekday (average Monday through Thursday), Friday, Saturday, and Sunday. Emissions of volatile organic compounds (VOC), carbon monoxide (CO), and oxides of nitrogen (NOx), are estimated for each county and day type on an hourly basis. The hourly estimates are computed by Highway Performance Monitoring System (HPMS) functional classification and area type (i.e., 21 area type?specific road categories). Emissions are categorized