Swapping Level of Service for Vehicle Miles Traveled in Project-Level Environmental Impact Analysis: Trends and Challenges in California

Automobile level of service (LOS) is the longest-standing and most commonly used performance metric in transportation impact analysis in the U.S. However, Senate Bill (SB) 743 upended that status quo for environmental impact review of land development projects in California, requiring that local governments analyze vehicle miles traveled (VMT) rather than LOS. In this study, we investigated how California’s local governments have responded to the mandated LOS-to-VMT switch. We obtained and analyzed information for 274 of the state’s 539 cities and counties, using expert interviews, documentary reviews, website searches, and communications with local government staff. We found that most jurisdictions had either adopted or were in the process of adopting their own VMT impact standards, though difficulties in implementing VMT-based standards were common and were more pronounced for smaller and more rural jurisdictions. In their standards, most jurisdictions hewed closely to the recommendations of the Governor’s Office of Planning and Research. Despite switching to VMT analysis for environmental review purposes, all respondent jurisdictions continued to use LOS outside the environmental review process. Overall, we found a consensus amongst our interviewees that swapping LOS for VMT could streamline development in urban areas but not in more suburban or rural jurisdictions. Our findings are specific to California, but they can provide useful guidance to other states or local governments outside of California that are considering adopting a VMT-based metric for transportation impact analyses.