ARB Research Seminar

This page updated April 12, 2017

Modeling Household Vehicle and Transportation Choice and Usage - Part A: Factors Related to Voluntary Choice of Low Vehicle Ownership and Usage

Photo of Patricia Mokhtarian

Patricia Mokhtarian

Photo of Giovanni Circella

Giovanni Circella

Patricia Mokhtarian, Ph.D., Professor, Civil and Environmental Engineering, Georgia Institute of Technology and Giovanni Circella, Ph.D., Senior Research Engineer, Civil and Environmental Engineering, Georgia Institute of Technology, and Researcher, Institute of Transportation Studies and National Center for Sustainable Transportation, University of California, Davis.

April 24, 2017
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA

Research Project


California has adopted regional plans to reduce greenhouse gas (GHG) emissions through coordinated transportation and land use planning as required by Senate Bill 375 (SB 375, the Sustainable Communities and Climate Protection Act of 2008) and has committed to reducing overall statewide GHG emissions by 40% below the 1990 levels by 2030 through Senate Bill 32 (SB 32, the California Global Warming Solutions Act of 2006). In order to meet both of these goals, significant changes in household transportation choices must be made.

This study analyzed travel survey and attitudinal data to investigate the impact of household demographics, individual attitudes, and residential location on vehicle ownership and usage decisions in California. The researchers identified characteristics of households that voluntarily choose to own fewer than expected vehicles and travel less by vehicle: they tend to be more ethnically and racially diverse, have fewer children, and live in rental units in very high density neighborhoods. Individuals with more pro-environmental attitudes and who like mass transit, biking and walking are more likely to live in zero-vehicle-owning households, while those who like driving and living in spacious homes with large yards are more likely to be in higher-than-expected vehicle-owning households. The research found that local density has non-linear effects on travel behavior: a given increase in density is associated with larger reductions in households' vehicle miles traveled (VMT) in lower-density neighborhoods than in higher-density ones, and this difference is larger in regions of lower-density with less than one million in population. Among higher-density neighborhoods, however, density increase is associated with larger reductions in VMT for households living in light rail-served regions. These results provide useful insights for promoting the adoption of more sustainable travel behavior, and support the State's efforts to promote infill development and reduce dependence on personal vehicles, including implementation of SB 375.

Speaker Biography

Patricia Mokhtarian, Ph.D., is a Professor of Civil and Environmental Engineering at the Georgia Institute of Technology. Dr. Mokhtarian is a leading expert on travel behavior utilizing the application of rigorous quantitative methods specifically to study the impacts of land use on travel behavior, the impacts of telecommunications technology on travel behavior, and attitudes toward mobility. Previously until 2013, Dr. Mokhtarian spent 23 years at the University of California, Davis as Associate Director of the Institute of Transportation Studies, and founding Chair of the interdisciplinary graduate program in Transportation Technology and Policy as well as a Professor of Civil and Environmental Engineering. She holds a Ph.D. and an M.S. in Industrial Engineering/Management Sciences from Northwestern University and a B.A. in Mathematics from Florida State University.

Giovanni Circella, Ph.D., is a Senior Research Engineer at the School of Civil and Environmental Engineering of the Georgia Institute of Technology, who currently shares his time with the University of California, Davis, where he is a professional researcher at the Institute of Transportation Studies and the National Center for Sustainable Transportation. Dr. Circella's expertise lies in the collection and quantitative analysis of behavioral data applied to analyze the impact of individual attitudes on travel, land use and transportation, the impact of shared mobility, on-demand ride services and automated vehicles on travel and auto ownership, and the mobility of specific population segments. He received his Ph.D. in Infrastructure Engineering and Transportation Planning from the Technical University of Bari (Italy), his M.S. in Agricultural and Resources Economics from the University of California, Davis, and his Italian Laurea (B.S. plus M.S. equivalent) degree in Civil Engineering from Technical University of Bari (Italy). .

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