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 (TTI-2002-12)

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 Implementation 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 2007. 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 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.