Official Title: Evaluating the Use of Red Light Running Photographic Enforcement Using Collisions and Red Light Running Violations
Authors: Christopher M. Cunningham, MS, EI and Joseph S. Hummer, Ph.D., PE
This is a 2004 study by the Institute for Transportation Research and Education North Carolina State University on the effects of red-light cameras in the city of Raleigh, North Carolina and the Town of Chapel Hill. This study compares the before and after crash statistics of 7 RLC intersections in those cities. The study uses 69 to 70 months of pre-RLC crash data compared to 4 to 5 months of post-RLC data. The statistics used in this analysis are from the North Carolina Department of Transportation and the study claims that 500 feet is 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. This study does not cover injury crashes. The results show that crashes at RLC-equipped intersections have decreased by 14% after RLCs were installed after the halo effect is taken into account. The study concludes that : "RLCs appear to have a positive affect... Based on the comparison group study, collisions were reduced in all four categories we examined by sizeable amounts."
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This is a very detailed 192 page study, the data and statistical analysis appear valid. The selection of 7 RLC intersections is a below-average number of intersections for this kind of study. The use of 500 feet as the Distance-From-Intersection inclusion zone for crashes far above average for most states. The before-RLC period is very long but the after-RLC period of 4 to 5 months is extremely short and makes the conclusions of this study much less useful. The conclusions of this study are supported by the data supplied.
This is a very well thought out and executed study, but according to Red-Light Camera company American Traffic Solutions: "six months of data is not enough time to judge them(red light cameras)."(external link), and this study uses even less post-RLC data, at only 4-5 months.