Senate Bill 375, signed into law in 2008, directed the California Air Resources Board to collaborate with the state’s metropolitan planning organizations (MPOs) to set regional targets for reductions in GHG emissions from passenger vehicles. The MPOs are required to adopt Sustainable Communities Strategies (SCSs) that lay out the strategies by which the region will achieve its GHG reduction target, including strategies to reduce vehicle miles traveled (VMT). Strategies to reduce VMT include changes to the built environment, to both land development patterns and the transportation system, that reduce the need for driving. The goal of this project was to document on-the-ground changes in the built environment in selected communities over a two-decade period and assess whether changes in VMT have occurred over the same period. A secondary aim was to explore the contribution of local and/or regional policy change and public investments such as transit, bike, and pedestrian infrastructure as well as private development investments to the observed on-the-ground changes to the built environment. This project comprised case studies of Sacramento, Fresno, and Santa Monica, communities that experienced notable changes in their transportation systems and land development patterns between 2000 and 2019. The first part of the case-study analysis focused on identifying changes to the built environment in the area and the factors contributing to those changes, including public policies (broadly defined) and market forces. The second part of the case-study analysis examined changes in travel patterns in the area over this period of time using available data sources. Estimates of VMT showed reductions over time, while estimates of the shares of trips by active transportation modes increased, though the small sample sizes on which estimates were based makes them highly uncertain. In these case studies changes to the built environment were associated with changes in travel behavior consistent with the goal of reducing VMT. To more robustly evaluate the impact of built environment changes on VMT in specific areas, better data on travel patterns must be collected before and after the changes occur.
