California Air Resources Board

Principal Investigator/Author: Yifang Zhu

Contractor: University of California, Los Angeles

Contract Number: 11-312

Project Status: Completed

Relevant CARB Programs: Health & Exposure, Climate Change

Topic Areas: Behavioral Change, Health Effects of Air Pollution

Research Summary:

The Complete Streets Act (Assembly Bill 1358), which was signed into law in September of 2008, requires cities and counties to account for the needs of all roadway users when updating their local general transportation plan. Also, the California Department of Transportation (CalTrans) revised an internal policy to adopt a Complete Streets Implementation Action Act (2008). As a result, California became the second state to implement a Complete Streets policy by designing roadways that are compatible to all types of transportation, including walking and cycling, as well as private vehicles and public transportation, with the goal of reducing the number of vehicle miles traveled (VMT) and their associated emissions. So far, there is little evidence on whether and how complete streets result in changes in travel behavior such as reductions in VMT. Although there has been active research on the relationship between the built environment and travel behavior, most of the studies tend to focus on a larger scale of the built environment such as land-use density and street networks. Traffic engineering studies, on the other hand, focus mostly on individual road design elements and their traffic flow impact. Currently, there is little research on how complete street designs impact travel behavior. Therefore, the goal of this project is to collect information in Southern California on the impacts of complete streets on travel behavior, including how such impacts would differ among different population groups and across different land-use contents (e.g. downtown business districts, urban mixed-use areas, and suburban residential areas) in roadways selected to represent typical arterial and local road types. This study will use two different designs, one will examine before-after comparisons by taking advantage of the conversion of an existing corridor to a complete street, and the other design will use six pairs of complete and incomplete streets matched to reduce differences in community location and socio-demographics. Both designs will evaluate the effectiveness of complete streets on local travel behaviors for different land-use contexts using traffic counts of all motorized and non-motorized travel modes and surveys to measure travel behavior changes. The results of this study will help to determine the effectiveness of complete streets conversions on the reduction in VMT. The study will quantify the effects of complete streets on travel behavior, as well as providing some information on barriers to changes in travel behavior. This information will help ARB in advising urban planners on complete streets designs that encourage the usage of active and public transportation.

Final Report: Please email research@arb.ca.gov to request the final report generated by this research contract.