Evaluation of Transit-Related Transportation Control Measures Final Report

The Northeastern Illinois region has been designated as a severe nonattainment area for ozone. Mobile sources provide a significant portion of ozone precursor emissions in the region. Transportation control measures (TCMs) must be used in nonattainment areas to achieve reductions in vehicle miles traveled (VMT) and mobile source emissions. The Regional Transportation Authority (RTA), as the agency charged with providing comprehensive planning for the region's transit system, has taken a lead role in developing transit-related (TCMs) for the region's mobile source component of the State Implementation Plan (SIP). To assist in the evaluation of TCMs, the RTA contracted with Barton-Aschman Associates, in association with Cambridge Systematics and Beata Welsh to develop an analytical "screening methodology" tool to provide an assessment of the effectiveness of selected transit-related TCMs in reducing VMT and mobile source emissions. The techniques developed to estimate the air quality impacts are designed to be transferable among TCM projects to allow the evaluation of similar types of transit projects. In addition, the analytical approach is designed to be "technically defensible" and includes the determination of key measures, such as changes in auto/transit mode split, changes in VMT, and the changes in emissions resulting from the implementation of transit TCM projects.