National Center for Sustainable Transportation
Boarnet, Marlon G. and Susan L. Handy (2017) NCST White Paper: A Framework for Projecting the Potential Statewide Vehicle Miles Traveled (VMT) Reduction from State-Level Strategies in California. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-17-40
The California Global Warming Solutions Act of 2006 (Assembly Bill 32) created a comprehensive, multi-year program to reduce greenhouse gas (GHG) emissions in the state to 80% below 1990 levels by 2050. With the recent passage of Senate Bill 32, the State of California has adopted an additional target of reducing greenhouse gas emissions to 40% below 1990 levels by 2030. To meet these goals, analysis shows that California will need to achieve an additional 7.5 percent reduction in light-duty vehicle miles of travel (VMT) by 2035, and an additional 15 percent reduction in light-duty VMT by 2050.
The California Air Resources Board (ARB) is thus considering a wide range of strategies for the 2016 Scoping Plan Update that focus on reducing demand for driving. These strategies fall into four general categories: Pricing, Infill Development, Transportation Investments, and Travel Demand Management Programs. The State has the ability to directly implement some of these strategies through state policy; for other strategies, the State can adopt policies that encourage or require the implementation of the strategy on the part of regional agencies, local governments, and/or the private sector.
In this paper, we consider the evidence available and assumptions needed for projecting statewide VMT reductions for each category of strategies. Our goal is to provide a framework for projecting the magnitude of reductions that the state might expect for the different strategies. This framework helps to illuminate the sequence of events that would produce VMT reductions and highlights important gaps in knowledge that increase the uncertainty of the projections. Despite uncertainties, the evidence justifies state action on these strategies: the available evidence shows that the strategies considered in this paper are likely to reduce VMT if promoted by state policy.
We do not in this paper examine the potential co-benefits of VMT-reduction strategies, including health, equity, and other benefits, but the evidence of these benefits is also strong and further justifies state action.