2007 On-Road Mobile Source Emissions Inventories For the Houston-Galveston Ozone Nonattainment Area (TTI-2002-5)

This Technical Note documents the methods the Texas Transportation Institute (TTI) used to develop the Houston-Galveston ozone nonattainment area (HGA) August 2007 on-road mobile source emissions estimates. These emissions forecasts are based on the August 2000 primary ozone episode meteorological conditions. (The August 2000 base-case episodespecific on-road mobile emissions estimates documentation, also produced under this task, are provided in a separate Technical Note.) The eight HGA counties are: Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery, and Waller. The forecast period for the emissions estimates is the 11-day base-year analysis sequence, Tuesday, August 22 through Friday, September 1. (Although the days-of-week are different for these dates in 2007, for modeling purposes the base-year episode date and dayof-week sequences are maintained.) Emissions of volatile organic compounds (VOC), carbon monoxide (CO), and oxides of nitrogen (NOx), are estimated for each county and day on an hourly basis. The hourly estimates are computed by network links (characterized by 13 road types) for which the geographical coordinates are provided. Emissions are categorized by 28 vehicle types and 14 pollutant-specific emissions types. For speed limit impact analyses, a second set of emissions estimates was produced for the scenario where the eight-county area maximum speed limits were reduced to SS mph.