The Impact of Red Light Cameras (Automated Enforcement) on Safety in Arizona

Red Light Cameras (RLCs) have been used in a number of U.S. cities to yield a demonstrable reduction in red light violations; however, evaluating their impact on safety (crashes) has been relatively more difficult. Accurately estimating the safety impacts of RLCs is challenging for several reasons. First, many safety related factors are uncontrolled and/or confounded during the periods of observation. Second, "spillover" effects caused by drivers reacting to non-RLC-equipped intersections and approaches can make the selection of comparison sites difficult. Third, sites selected for RLC installation may not be randomly selected, and as a result may suffer from the regression to the mean effect. Finally, crash severity needs to be considered to fully understand the safety impacts of RLCs. With these challenges in mind this study was designed to estimate the safety impacts of RLCs on traffic crashes at signalized intersections in the state of Arizona and to identify which factors are associated with successful installations. RLC equipped intersections in the cities of Phoenix and Scottsdale are examined in detail to draw conclusions as to the relative success of RLC programs in these two jurisdictions. Both jurisdictions are operating successful installations of RLCs. Factors related to RLC effectiveness appear to include crash type and severity, left-turn phasing, presence of warning signs, approach speeds, and signal timing. Recommendations are made as to under what conditions should RLCs be considered.

  • Record URL:
  • Corporate Authors:

    University of Arizona, Tucson

    Transportation and Traffic Institute
    Tucson, AZ  United States  85721

    Arizona Department of Transportation

    206 South 17th Avenue
    Phoenix, AZ  United States  85007

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Washington, Simon P
    • Shin, Kangwon
  • Publication Date: 2005-8


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; References; Tables;
  • Pagination: 139p

Subject/Index Terms

Filing Info

  • Accession Number: 01010926
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-AZ-05-550
  • Contract Numbers: SPR-PL-1-(61) 550
  • Created Date: Nov 28 2005 2:16PM