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Definition of an accident

For those who have read my studies, know that an important differentiator between the studies has been the time period of analysis.  In 2009, IDOT changed the definition of an accident and so it was unfair to compare accidents prior to the change with accidents after the change.  While this may seemed nuanced, it makes a big difference when lookinig at whether cameras reduce accidents.  Chicago was able to take advantage of this in their push for red light cameras.  In an article by the Daily Herald, they focus on this issue:

The article also notes the lack of public access to the data.


Red-light cameras began proliferating at suburban intersections in 2009 with the justification that they would prevent crashes. The same year, the Illinois Department of Transportation raised the dollar threshold necessary to report property damage crashes from $500 to $1,500. In one fell swoop, reported crashes shrank statewide by 30 percent -- from an average of 413,235 a year to an average of 287,718, IDOT officials said.

How much of the credit for reducing crashes should go to red-light cameras?

 . . 

The 2009 shift isn't the only problem in trying to objectively analyze red-light camera data. The Daily Herald's analysis also found an inconsistent system of reporting crash data to IDOT and lack of public access to statewide data.

That's why a number of experts and good government groups are calling for greater transparency and reforms in how crash data is reported.

IDOT updated the property damage standard in 2009 to reflect higher vehicle repair costs.

"As a result, a lot fewer accidents were reported," surveillance camera expert Rajiv Shah said.

The reduced crash rates partly deflected the public uproar over red-light cameras at that time.

But the decline in crashes did not carry through to 14 suburban intersections where cameras were installed after 2009.

One intersection had incomplete data, but at 10 of the 13 others crashes decreased in 2009 -- before cameras were in place at those locations.

After cameras were installed, crashes increased or stayed the same at eight of the 14 intersections, or 57 percent.

"I think everybody was a bit oversold on the promise of cameras being like that silver bullet and reducing crashes," said Shah, an adjunct associate professor of communications at the University of Illinois at Chicago who has studied and written about red-light cameras.

 . . 

Obtaining statewide data requires a Freedom of Information Act request and an in-person visit to IDOT offices.

"One of the primary objectives of making the post-installation reports accessible is transparency," IDOT spokesman Guy Tridgell said. "We make them readily available for members of the public interested in learning more about the impact red-light cameras are having on their communities.

"The Illinois Department of Transportation is currently exploring other options that could give us a better picture of how effective the cameras are at improving safety," he said.

The state of Illinois requires municipalities with red-light cameras to provide one- and three-year reports on the cameras. But the data is submitted on paper, not electronically. The law is vague, only requiring a statistical analysis "based upon the best available crash, traffic, and other data."

The law tells local officials to undertake additional studies if crashes have increased in lanes monitored by cameras. However, it leaves it up to their discretion whether to take action to rectify the problem. In a number of cases, the reports are prepared by red-light camera vendors.

Shah supports a comprehensive public database of crashes.

"It should be open to the public to review to be sure these cameras are indeed effective -- and if not -- remove them and put in place a warning program. It would be much more sensitive and transparent."

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