STI, in collaboration with faculty and researchers at U.C. Davis, developed an on-road motor vehicle emissions modeling tool that quantifies emissions of carbon dioxide (CO2), criteria pollutants, and mobile source air toxics (MSATs) that originate from transportation projects. The tool, called CT-EMFAC, allows users to pair emission factors from California's EMFAC motor vehicle emissions model with forecasted transportation activity (fleet mix, speed distribution, vehicle miles traveled). In addition, the tool incorporates MSAT speciation factors developed by the California Air Resources Board.
The results of this work will
  • Allow, for the first time, project analysts to estimate CO2, criteria pollutant, and MSAT on-road emissions with a single tool
  • Give analysts a tool to evaluate how transportation emissions vary with travel speed, calendar year, geographic location, and fleet changes
  • Enable project analysts to easily pair activity data with emission factors to evaluate project impacts