Quantifying Reductions in Vehicle Miles Traveled from New Pedestrian Facilities: Technical Documentation

This report summarizes research outcomes in an effort to update the California Air Resources Board (CARB)’s current methodology for estimating greenhouse gas (GHG) emission reductions from adding new pedestrian facilities, including sidewalks and shared-use Class I bicycle paths. At least three programs offer Greenhouse Gas Reduction Fund (GGRF) funding for projects with new pedestrian facilities. To measure GHG emissions reductions from new pedestrian facilities, CARB currently relies on a method (the “congestion mitigation and air quality improvement (CMAQ) method”) it published with Caltrans in 2005 for calculating GHG emissions reductions from new bicycle facilities. The data on which that method is based are even older, mostly from the 1990s. This report reviews the more recent literature to determine whether and how the CMAQ method could be modified to better reflect emerging data and methods. This review summary focuses on the first—and most difficult—step in the GHG emissions reduction quantification method: estimating reductions in vehicle miles traveled (VMT). CARB currently uses the same equation for estimating VMT reductions from new pedestrian facilities as for estimating reductions from bicycle facilities. This equation is based on bicycling research, which is separately reviewed in the companion technical report, “Quantifying Reductions in Vehicle Miles Traveled from New Bike Paths, Lanes, and Cycle Tracks” (Bike Facility Report). The evidence in the literature reviewed for this report is too limited to justify developing a separate estimate on methodology just for pedestrian infrastructure. However, the literature indicates an opportunity to update multiple factors in the current methodology for use with pedestrian facilities, some based on the pedestrian facility literature and some, where the walking literature is lacking, based on the bicycling literature. View the NCST Project Webpage