12/10/2005North Carolina Buys Positive Speed Camera Study
Full text of a Charlotte, North Carolina speed camera study raises objectivity questions.
The North Carolina Governor's Highway Safety Program paid the Institute for Transportation Research at Education (ITRE) $141,102 to produce a study supporting the use of speed cameras in Charlotte. The study was released Wednesday with a press release that proclaimed, "Automated enforcement of speed improves safety." A closer examination shows the results, however, are less clear.
The press release, for example, purports to show public acceptance of the new ticketing technology is high. "Overall, the perception of photographic enforcement was positive," ITRE's release states. The survey examined the opinion in a focus group that consisted of homeowner's association activists and transportation officials -- individuals with a personal stake in the issue not necessarily representative of the public as a whole. According to page 29 of the report, "Every group had members that were involved in red light automated enforcement either directly or indirectly."
The press release also touts the reductions in speed achieved by the photo radar devices, but the report's text shows this reduction was less than one MPH. According to page 76, the control sites without cameras also experienced a decrease in median speed of 0.28 MPH. Comparatively, the reduction at the camera sites was indeed greater -- speeds at camera sites were reduced by 0.88 MPH.
The press release claims this minor reduction in speed produced a twelve percent reduction in accidents. In the full report, the claim is followed with a warning on no less than five occasions that, "readers must keep in mind the serious limitations of the study (such as short duration of the after period, intense media attention on the program, and others) before attempting to generalize this finding." The warning refers to the fact that the results are based on a mere four months of data, running from September 2004 to December 2004. Moreover, a majority of the sites without speed cameras also experienced a drop in accidents (pg. 110).
The Governor's Highway Safety Program has paid ITRE $433,281 for a number of studies with research associate Christopher Cunningham, the latest report's main author. One of the team's prior projects was a $135,490 examination of how to expand the use of photo enforcement in the state.
The full study is available in a 1.7mb PDF file at the source link below.