California Air Resources Board

Principal Investigator/Author: Susan Handy  

Contractor: University of California, Davis

Contract number: 20RD006

Project Status: Completed February 2024

Relevant CARB programs: Sustainable Communities & Climate Protection Program, Research Planning

Topic areas: Sustainable Communities, Research & Sustainable Communities, Sustainable Community Strategies (SCS), Vehicle Miles Traveled (VMT) Reduction & Climate Goals, Land Use & Transportation Research

Research Summary:

The goal of this project is to assess the degree to which on-the-ground changes in selected communities have produced reductions in vehicle miles traveled (VMT). A secondary aim is to examine the degree to which local and/or regional policy change brought about the observed on-the-ground changes. This project will complete a minimum of three case studies of local communities that have experienced substantial changes in the transportation system and/or land development patterns to assess the change in VMT that has resulted; the forces contributing to transportation and land use changes, including local and/or regional policy changes, will also be examined. These case studies may provide examples of best practices to achieve Sustainable Communities Strategies (SCS) goals as well as insights on barriers to successful SCS implementation.

The goal of this project is to develop an in-depth understanding of changes in travel behavior resulting from changes in land-use patterns and the transportation system in specific case study areas. In essence, the goal is a "before-and-after" study of the effects of such changes, but the study is being conducted after the fact and thus will be relying on available and/or reconstructed sources of "before" data. The first part of the case-study analysis focuses on identifying the causal factors: what changes occurred in the area and what forces brought about those changes? An important question here is the degree to which transportation and land use changes resulted from public policies and programs versus market forces. The second part of the case-study analysis focuses on the outcome: how did VMT change in the area over the period of time, and what conditions enhanced or dampened the change in VMT? To the degree possible, the case studies will draw on data and analysis in a companion project that is using "big data" to assess changes in VMT throughout the state.

Keywords: Vehicle Miles Traveled (VMT); transportation trends; sustainable community strategies (SCS); greenhouse gas reduction strategies; big data; transportation and land use

Research Seminar