Official Title: The Impact of Red Light Cameras (Photo-Red Enforcement) on Crashes in Virginia
Authors: NICHOLAS J. GARBER, Ph.D., P.E., JOHN S. MILLER, Ph.D., P.E., R. ELIZABETH ABEL, SAEED ESLAMBOLCHI, SANTHOSH K. KORUKONDA
This is a 2007 study by the Virginia Transportation Research Council on the effects of red-light cameras in several cities in the state of Virginia. This study compares the before and after crash statistics of 28 RLC intersections in that state. The study uses 4 to 36 months of pre-RLC crash data compared to 8 to 80 months of post-RLC data. The statistics used in this analysis are from various municipalities all with different reporting standards but the report does define that they used 150 feet as their Distance-From-Intersection inclusion zone for crashes. This study does use comparison control intersections to help validate the analysis of the data. There are no data or conclusions in this report that suggest a reduction or increase in fatalities due to RLCs. The study shows that there was an overall increase in total crashes of 23% and an injury crash increase of 17% after the installation of RLCs at intersections. The study concludes that: "the cameras are associated with a net increase in comprehensive crash costs", and "These results cannot be used to justify the widespread installation of cameras because they are not universally effective. These results also cannot be used to justify the abolition of cameras, as they have had a positive impact at some intersections and in some jurisdictions."
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This is a very detailed 149 page study, the data and statistical analysis are not standard or thoroughly explained. The selection of 28 RLC intersections is well above average for this kind of study. The defined Distance-From-Intersection inclusion zone for crashes of 150 feet is the same as recommended by the Federal Highway Administration and adds to the consistency and validity of the data. The before and after RLC date periods of as few as 4 months of before RLC data and as few as 8 months of after-RLC data is less than optimal for this type of analysis and somewhat reduces the validity of this study. The validity of this study would have been improved if some of this short-time-period data had been excluded. This is a very well thought out and executed study with explanations of every element of how the data collection and analysis was conducted. The conclusions are supported by the data.