Overview
California’s climate and sustainability policies rely heavily on accurately measuring and reducing vehicle miles traveled (VMT). Under state law, many development and transportation projects cannot be approved without first estimating and mitigating their VMT impacts. Yet the methods currently used to produce these estimates are often imprecise, inconsistent across agencies, and insufficiently grounded in the latest data and research. Such inaccurate VMT accounting means the state may be failing to reduce driving as much as its policies intend, and potentially spending resources inefficiently in the policy implementation process.
UC ITS aims to improve the credibility and accuracy of VMT forecasts used in project-level environmental review across California. The research focuses on both land development projects and transportation infrastructure projects, using emerging data sources — particularly mobile phone location data — alongside traditional methods to produce more rigorous, transparent, and policy-ready VMT estimates.
- Create an improved VMT measurement framework. Develop and validate a VMT measurement framework that integrates mobile phone location data, administrative odometer records (to the extent they are available), and infrastructure sensors. The framework will produce high-resolution, auditable VMT estimates with explicit uncertainty bounds, thereby addressing limitations of current sketch-level tools, travel demand models, and proprietary commercial data products.
- Evaluate current VMT estimation practices by state, regional and local agencies under CEQA for transportation and land development projects. This includes reviewing case studies, interviewing practitioners in California, and examining VMT reduction policies and methods in other states. The goal is to identify strengths, weaknesses, and gaps in current practice.
- Develop improved VMT forecasts for land development and transportation projects. Estimate causal relationships between land development and transportation projects and VMT levels using multiple methods and data sources, including phone-based, survey-based, and sensor-based measures.
- Design “no-build” counterfactual scenarios for forecasting project-level VMT impacts. Examine how to define the appropriate “no-build” counterfactual scenario — a critical and often underspecified element of current VMT mitigation analysis — for housing and nonresidential development projects.
- Develop new empirical estimates of the VMT effects of non-highway transportation projects commonly treated as VMT mitigation measures. This includes transit investments, active travel infrastructure, or streetscape improvements.
Marta Gonzalez
Professor, City & Regional Planning and Civil and Environmental Engineering, UC Berkeley
Susan Handy
Distinguished Professor, Environmental Science and Policy, UC Davis
Elisa Barbour
Assistant Professional Researcher, Institute of Transportation Studies, UC Davis
Jamey Volker
Professional Researcher, Institute of Transportation Studies, UC Davis
Kome Ajise
Executive Director, Southern California Association of Governments
Drew Cooper
Senior Manager of Data and Forecasting, San Francisco County Transportation Authority
Frank Jimenez
Principal Fiscal and Policy Analyst, Legislative Analyst’s Office
Dov Kadin
Senior Planner, Sacramento Area Council of Governments
Julia Kingsley
Deputy Secretary Environmental Policy and Housing Coordination, California State Transportation Agency
Aaron Kurz
Senior Consultant, Assembly Transportation Committee
Alex Levin
Acting Deputy Director of Sustainability, Caltrans
Zachary Miller
Principal Transportation Planner, Governor’s Office of Land Use and Climate Innovation
Andrew Quinn
Project Director, HNTB
Annalisa Schilla
Chief, Sustainable Transportation and Communities Division, California Air Resources Board
Kiana Valentine
Partner, Politico Group
Jeanie Ward-Waller
Director of Transportation Advocacy, Fearless Advocacy
Melissa White
Principal Consultant, Senate Transportation Committee
Cherry Zamora
Associate Deputy Director, Environmental Policy, California Transportation Commission
