Evaluation of Innovative Safety Treatments. Volume 1: A Study of the Effectiveness of White Enforcement Lights

The Florida Department of Transportation (FDOT) in cooperation with local engineering and enforcement agencies installed white enforcement lights at a number of intersections on the State Highway System in Hillsborough County to help police officers safely enforce red light violations. These lights were placed either above or below the signal head, so that they are visible from a complete circle of 360 degrees. Thus, a single officer positioned downstream from the intersection can safely observe the violation, stop the offending driver, and issue the citation. White lights can therefore potentially replace a police officer, reducing the required police manpower by half. This either could allow enforcement at more intersections or could increase enforcement hours at the same number of intersections. The increased enforcement could in turn help change driver behavior and reduce the number of red light violations and associated crashes. This report documents the findings and conclusions of a study conducted to determine the effectiveness of white lights in reducing red light violations and associated crashes. The red light violation data collected at the study intersections before and after the installation of white lights indicates that the total number of violations (AM and PM hours combined) was reduced from 759 to 567. The one-tailed t-test indicated that the reduction in the number of violations is statistically significant at a 90% confidence level. Crash frequencies and rates for the before and after periods were also compared. The analyses showed that while the average annual crash frequency of all crashes had increased from 828 to 860, the number of red light running crashes that occurred on the approaches equipped with white lights was reduced from 40.17 to 28. The one-tailed paired t-test indicated that the reduction was significant at a 95% confidence level. The analyses using the crash rates also indicated that the reduction in the crash rate for red light running crashes occurring on the approaches with white lights was statistically significant at a 95% confidence level. The analyses conducted as part of this study show that better enforcement of red light compliance made possible by the installation of white lights has the potential to reduce red light violations and associated crashes. This is indicated by the analyses of a surrogate measure (number of red light violations) as well as a direct measure (crash frequency). Among the two measures, the variation in the number of red light running crashes between intersections was higher than the variation in the number of violations. Due to this higher variation, the results obtained from analyses of the crash data are less conclusive than the results obtained from analyses of the violation data. In other words, while the confidence level and the power of statistical tests are reasonable in the case of violation data, it is not the case with crash data. Therefore, it is recommended that crash data at additional intersections be collected and analyzed as it becomes available for conclusive evidence of the potential benefits of white lights in reducing red light running crashes.

• Record URL:
  • http://www.dot.state.fl.us/research%2Dcenter/Completed_Proj/Summary_SF/BD500/BD500_v1_rpt.pdf
• 
• Corporate Authors:

  HNTB Corporation

  6363 NW 6th Way, Suite 420
  Fort Lauderdale, FL  United States  33309

  University of Central Florida, Orlando

  Department of Civil and Environmental Engineering
  P.O. Box 162450
  Orlando, FL  United States  32816-2450

  Florida Department of Transportation

  605 Suwannee Street
  Tallahassee, FL  United States  32399-0450
• Authors:
  • Reddy, Vivek
  • Abdel-Aty, Mohamed
  • Pinapaka, Satya
• Publication Date: 2008-1

Language

• English

Media Info

• Media Type: CD-ROM
• Edition: Final Report
• Features: Appendices; Figures; Photos; References; Tables;
• Pagination: 46p

Subject/Index Terms

• TRT Terms: Before and after studies; Countermeasures; Crash rates; Highway safety; Innovation; Red light running; Signal lights; Traffic crashes; Traffic law enforcement; Traffic safety; Traffic violations; White
• Geographic Terms: Florida
• Subject Areas: Highways; Safety and Human Factors; Security and Emergencies; I82: Accidents and Transport Infrastructure; I83: Accidents and the Human Factor;

Filing Info

• Accession Number: 01091744
• Record Type: Publication
• Report/Paper Numbers: 40502-PL-003-001
• Contract Numbers: B-D500
• Files: TRIS, STATEDOT
• Created Date: Apr 23 2008 9:27AM