Davenport and Council Bluffs, IA, USA 2007 RLC study

Official Title: The Effectiveness of Iowa’s Automated Red Light Running Enforcement Programs

Authors: Eric J. Fitzsimmons, Shauna Hallmark, Thomas McDonald, Massiel Orellana, and David Matulac

Summary:
This is a 2007 study by the Center for Transportation Research and Education at Iowa State University on the effects of red-light and speed-detection cameras in the cities of Davenport and Council Bluffs, Iowa. This study compares the before and after crash statistics of nine RLC intersections in those cities. The study uses 36 months of pre-RLC crash data compared to 12-24 months of post-RLC data. The statistics used in this analysis are from the cities' Police Departments which use 25 meters(82 feet) as their Distance-From-Intersection inclusion zone for crashes. here are no data or conclusions in this report that suggest a reduction or increase in fatalities due to RLCs. This report does not cover injury crashes. The results show that crashes at RLC-equipped intersections have decreased about 20% by quarter over the study period, using Bayesian analysis.

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Comments:
This is a detailed 139 page study, the data and statistical analysis appear valid. The selection of 9 RLC intersections is a below-average number of intersections for this kind of study. The use of 82 feet as the Distance-From-Intersection inclusion zone for crashes is below the average for most states and the Federal Highway Administration, and slightly diminishes the validity of the conclusions of this study by excluding some intersection-related crashes from their statistics. There is a comparison of control intersections, but no mention of the total intersection-related crashes city-wide as many other studies mention. Another diminishing factor of this study is that these RLC cameras also issued speeding tickets during the course of study period, which is something that is very rare to include in these kind of studies. For some unexplained reason the statistical analysis is done per-quarter(groupings of 3 months) instead of monthly or yearly, this is the only study we could find that was done in this way. The majority of the after-RLC data is only for 12 months and only had a simple statistical analysis done on it. It is stated that a more thorough Bayesian analysis would be done when 2007 traffic data was made available, but 3 years later no report or analysis has been released. The conclusions of this study are supported by the data supplied.

Notes:
The RLCs installed in the City of Clive, IA are also mentioned in the study and take up many of the study's pages, but none of the statistics used are from Clive because of how new those installations were.

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St Pete Driver,
Dec 23, 2012, 5:35 AM
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