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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
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Publication Number: FHWA-HRT-05-048
Date: April 2005
Safety Evaluation of Red-Light Cameras
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Part of the difficulty in defining specific study questions early in the project was the lack of information on data availability and range for the different issues. While the project team (and the FHWA panel) had some insight into what data might be available on a State-controlled roadway system, there was less knowledge about what would be available in city or county data systems. For this reason, a decision was made to interview a small sample of key cities across the U.S. to address these questions.
The "sampling frame" for these interviews was based on a November 2002, list provided by the ITS Joint Program Office. As part of their periodic survey of ITS deployment in 78 of largest metropolitan areas in the U.S., a set of questions asked about current and projected numbers of intersections where RLC systems were installed. An additional listing of jurisdictions with RLC programs was extracted from a Web page listing developed by the Insurance Institute for Highway Safety. Additional cities were added based on panel knowledge and on a separate study where RLC programs were being surveyed.
The initial idea was to conduct a survey of a random sample of jurisdictions in this combined listing to determine, in general, what data might be available. (Note that only limited funds had been set aside for this task at the inception of the project.) However, after the detailed interview form was developed and tested, it became apparent that the interview would require 30-50 minutes of time with pertinent city/county staff, that it was often difficult to identify and reach the appropriate staff (even with the ITS contacts on the JPO listing), and that staff in more than one city/county agency would usually have to be contacted due to the cross-agency nature of this program (i.e., both traffic and police staff). For these reasons, a decision was made to interview cities with 10 or more RLCs already in operation. Emphasis was also placed on cities that had a significant number of such treated locations in place in 1999 or earlier-sites that would be useful in a retrospective study requiring at least a 2-year "after" period. While "nonrandom," this provided information on cities that were potential future participants in the actual evaluation. Within the time frame and budget, project staff interviewed 15 jurisdictions.
While most of these interviews were completed by phone (as were follow up questions), two jurisdictions chose to complete the interview in writing. This led to some missing data for a limited number of questions. However, in general, the interview process did produce detailed data on both the nature of the RLC program and the availability of various forms of data in each jurisdiction. (The interview form and a summary of the results are available from the authors on request.) The results of the interviews will be provided at the end of the following section.