U.S. Department of Transportation
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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
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| This report is an archived publication and may contain dated technical, contact, and link information |
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Publication Number: FHWA-HRT-05-048
Date: April 2005 |
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Safety Evaluation of Red-Light CamerasPDF Version (621 KB)
PDF files can be viewed with the Acrobat® Reader® FOREWORD This is a final report on a study to evaluate the effectiveness of red-light-camera (RLC) systems in reducing crashes. The intended audience is professionals who make decisions about safety programs for intersections. The study involved empirical Bayes before-and-after research using data from seven jurisdictions across the United States to estimate the crash and associated economic effects of RLC systems. The study included 132 treatment sites and specially derived rear end and right-angle unit crash costs for various severity levels. Crash effects detected were consistent in direction with those found in many previous studies: decreased right-angle crashes and increased rear end crashes. The economic analysis examined the extent to which the increase in rear end crashes negates the benefits for decreased right-angle crashes. There was indeed a modest aggregate crash cost benefit of RLC systems even when accounting for the negative impact of rear end collisions. The benefit of RLC systems could increase further, if measures were taken to educate or alert drivers that vehicles preceding them could be stopping suddenly for a red light and thus reduce the likelihood of a rear end crash. A disaggregate analysis found that the greatest economic benefits are associated with the highest total entering average annual daily traffic, the largest ratios of right-angle to rear end crashes, and with the presence of protected left-turn phases. There were weak indications of a spillover effect that point to a possible need for a more definitive, perhaps prospective, study of this issue. Michael F. Trentacoste, Director Notice This document is disseminated under the sponsorship of the
U.S. Department of Transportation in the interest of information exchange. The
U.S. Government assumes no liability for the use of the information contained in this document. The
U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report only because they are considered essential to the objective of the document. Quality Assurance Statement The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement. Technical Report Documentation Page
SI* (Modern Metric) Conversion Factors Table of ContentsPage Phase I-Evaluation Design IV. Literature Review of Critical Studies Summary of Findings V. Determination of Study Questions to be Answered VI. Determination of RLC-Related Data Availability VII. Methodology for National, MultiJurisdiction Study Study Design Details VIII. Study Methodology for Economic Analysis Initial Economic Analysis Study Design Crash Data Crash Data Linkage to Intersections Composite Effects at Camera sites XII. Discussion and Conclusions Appendix A. Sources of Data by Jurisdiction Appendix B. Number of Treated, Reference, and Comparison Sites in Each Jurisdiction List of FiguresList of TablesTable 1. Summary of findings from past studies Table 2. Summary of results for right-angle injury crashes at site (i) Table 3. The composite effect over several sites (for illustration) Table 4. P-values for various sample sizes and expected changes in safety Table 5. After period crash rate assumptions Table 6. Sample analysis for right-angle crash effects Table 7. Sample analysis for rear end crash effects Table 8. Best judgment on possibility of detecting safety effects Table 9. Best judgment on sites to use based on crash and noncrash data available Table 11. Definitions of crash types used in the analyses for each jurisdiction Table 12. Safety performance functions for the signalized intersections reference group Table 13. Combined results for the seven jurisdictions Table 14. Results for individual jurisdictions Table 15. Before-and-after results for total crashes at spillover intersections Table 16. Original comprehensive crash cost estimates for urban signalized intersections Table 17. Economic effects including and excluding PDOs Table 18. Severity-level distributions for right-angle and rear end injury |
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