CT-EMFAC Modeling Tool: Estimating On-Road GHG, Air Toxics, and Criteria Pollutant Emissions

Sonoma Technology, in collaboration with faculty and researchers at U.C. Davis, developed an on-road motor vehicle emissions modeling tool, CT-EMFAC, to facilitate streamlined project-level emissions analyses. CT-EMFAC quantifies emissions of criteria pollutants, greenhouse gases (GHGs), and mobile source air toxics (MSATs) that originate from transportation projects. The tool allows users to pair emission factors from the California Air Resources Board’s (CARB) EMFAC motor vehicle emissions model with forecasted transportation activity (fleet mix, speed distribution, vehicle miles traveled) for multiple roadway links across multiple project scenarios. The tool calculates road dust emissions using the U.S. Environmental Protection Agency’s Compilation of Air Pollutant Emissions Factors (AP-42) method and incorporates MSAT speciation factors developed by CARB. Using consumption factors calculated from EMFAC data, CT-EMFAC also calculates the fuel and electricity consumed by vehicles in operation.<br>

The CT-EMFAC tool<br>
<ul><li>Allows project analysts to estimate on-road emissions, as well as fuel and electricity consumption, within one graphical user interface.</li>
<li>Supports GHG assessments by calculating emissions from multiple GHG pollutants and by calculating carbon dioxide equivalent (CO₂e) emissions.</li>
<li>Gives analysts a tool to evaluate how transportation emissions and fuel consumption vary with travel speed, calendar year, geographic location, and fleet changes.</li>
<li>Enables project analysts to easily pair travel activity data with emission factors to evaluate project impacts.</li>
<li>Supports project-level energy assessments.</li>
<li>Supports particulate matter hot-spot assessments by providing emissions inputs for the AERMOD dispersion model (EM4AQ mode).</li></ul>