San Diego, CA, USA 2002 RLC Study

Official Title: IMPACTS OF THE SAN DIEGO PHOTO RED LIGHT ENFORCEMENT SYSTEM ON TRAFFIC SAFETY

Authors: Jacqueline M. Golob, Seongkil Cho, James P. Curry P.E., Thomas F. Golob

Summary:
This is a 2002 study by PB Farradyne and the Institute of Transportation Studies at the University of California on the effects of red-light cameras in the city of San Diego, California. This study compares the before and after crash statistics at 19 intersections in that city. The study uses at least 39 months of pre-RLC crash data compared to 12-34 months of post-RLC data. This study uses a comparison of monitored approaches, not intersections, for it's crash data and analysis. The statistics used in this analysis were supplied by the City of San Diego's Traffic Engineering Department and the report did not define what they used as their Distance-From-Intersection inclusion zone for crashes. There are no data or conclusions in this report that suggest a reduction or increase in fatalities due to RLCs. The study concludes that: "crashes attributable to red light running decreased after implementation to approximately 60 percent of pre-enforcement rates, while rear end crashes increased to approximately 140 percent of pre-implementation levels"

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Comments:
This is a brief 18 page report, the data and statistical analysis are not standard or thoroughly explained. The selection of 19 RLC intersections is an average number of intersections for this kind of study. The use of "monitored approaches" instead of intersections as the analysis metric is not the standard for this kind of study. In fact, only one other related study(Houston, TX 2002) uses this method, and it is not explained why they chose this non-standard measurement method. The lack of a defined Distance-From-Intersection inclusion zone for crashes somewhat diminishes the conclusions. The before and after RLC date periods are sequential but several intersections only having 12 months of after-RLC data is less than optimal for this type of analysis. The conclusions of this study are supported by the data supplied, but are less convincing than most of the other studies on the subject.
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St Pete Driver,
Dec 23, 2012, 6:02 AM
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