UC Davis Institute of Transportation Studies

This project reviews and summarizes empirical evidence for a selection of transportation and land usepolicies, infrastructure investments, demand management programs, and pricing policies for reducingvehicle miles traveled (VMT) and greenhouse gas (GHG) emissions. The project explicitly considers socialequity (fairness that accounts for differences in opportunity) and justice (equity of social systems) forthe strategies and their outcomes. Each brief identifies the best available evidence in the peer-reviewedacademic literature and has detailed discussions of study selection and methodological issues.

VMT and GHG emissions reduction is shown by effect size, defined as the amount of change in VMT (orother measures of travel behavior) per unit of the strategy, e.g., a unit increase in density. Effect sizescan be used to predict the outcome of a proposed policy or strategy. They can be in absolute terms (e.g.,VMT reduced), but are more commonly in relative terms (e.g., percent VMT reduced). Relative effectsizes are often reported as the percent change in the outcome divided by the percent change in thestrategy, also called an elasticity.