Monday, November 23, 2009

City & State Differ on Effectiveness of Red-Light Cameras

Hate them or love them red-light cameras are a hot topic. We had a post on them a month ago and yesterday the Chicago Tribune had an informative piece on the discussion around them:
Cameras (red-light cameras at intersections) are said to reduce accidents, but collision records compiled by the Illinois Department of Transportation (IDOT) indicate that accidents increased at many city intersections the year after red-light cameras were installed. In fact slightly more intersections saw an increase than a decrease, the data show.

The city tells a very different story. Crash statistics compiled by the city reflect broad success in reducing accidents with cameras, and the city could not explain why the numbers are so different.

Overall the article claims that nearly 60 percent of intersections with red-light cameras had an increase in accidents based on the following analysis:
With or without cameras accident totals fluctuate year to year at every intersection. For that reason the Tribune analysis of accident trends treated crash numbers that rose or fell less than 10 percent as essentially unchanged.

The read from the state numbers is this: Although some Chicago intersections indeed appear to benefit from the presence of cameras, nearly 60 percent do not.

So what about the Sloop? As of now only the State and Roosevelt intersection has statistics to look at:
So based off of IDOT's information, the Tribune would classify this South Loop intersection as one where the presence of red-light cameras caused more accidents. The city's numbers would prove the opposite. Judge for yourself.

The one thing these numbers don't take into account is increased traffic. Although we're not 100% sure, we assume the amount of traffic in the South Loop (particularly at this intersection) has increased from 2005 to 2008.

For more information specific to other intersection check out this Chicago Tribune link.

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