Chicago Red Light Camera Study Shows Mixed Results

Total Crashes Unchanged In Before & After Study

Does red light camera enforcement actually work?

This has been the question since red light cameras were first introduced to Chicago intersections under the auspices of improving traffic safety back in 2003.

And now, with City Hall trying to use the claims of safety improvements from Chicago’s red light camera system to rationalize adding speed enforcement to city streets, understanding RLC effectiveness may play into the debate.

The city has always contended its RLC enforcement program has been an overwhelming success and touted its safety benefits to sell the public on the idea of building an equally expansive speed camera system here.

Critics, many of them victims of the $100 camera fines, believe red light cameras are about revenue and not safety.

But a study conducted by the Chicago Department of Transportation on the effectiveness of the city’s red light camera program seems to undermine the city’s own position on the safety benefits of the RLC enforcement.

The study obtained from CDOT through a Freedom of Information request by The Expired Meter, seems to show either amazing safety gains, or mixed results or at worst, safety declines depending on who you listen to.

CDOT did a study of 96 intersections utilizing RLC enforcement and compared crash data for each intersection for two years before the cameras were installed with crash data for the two years after installation.

Surprisingly, in the aggregate, total crashes were virtually unchanged dropping only a fraction of one percent from 2,072 crashes before the cameras were installed to 2,066 crashes after installation.

“What the study shows is that red light cameras reduce the total number of crashes, particularly right angle crashes which are the  most dangerous,” says city spokesperson Tom Alexander.

But Professor Rajiv Shah, an Adjunct Assistant Professor in the Department of Communication at the University of Illinois at Chicago disagrees.

Shah, conducted a study of Chicago’s RLC system in 2010 analyzing crash data and which came up with similar results.

“I thought the results (of CDOT’s study) were pretty consistent with what I had found and pretty consistent with the idea that red light cameras are not effective in improving safety,” says Shah. “The report does not show a significant decrease in crashes.”

Right Angle Crashes Down, Rear End Crashes Up

When broken out by crash type, right angle collisions declined from 543 crashes before cameras to 390 after cameras or a 28% reduction. However, rear end crashes went from 485 before cameras to 697 after cameras–a nearly 44% increase. This breaks down to an average reduction in three right angle crashes and an average increase of four rear end crashes per intersection over two years.

Traffic safety experts do generally agree that right angle or T-bone crashes are more dangerous than rear end impacts. However, Shah points out if one looks at overall crash trends, the city’s drop in right angle crashes is nearly identical to the 27.7% decrease in overall crashes reported by CDOT for the same time period and therefore the gains in reducing right angle crashes cannot be completely attributed to the cameras.

“Our position is that automated enforcement doesn’t just change the behavior of that particular location but at intersections city wide,” says CDOT Managing Deputy Commissioner Scott Kubly.

Can’t Compare To Chicago

Alexander also doesn’t  think it’s fair to compare the largest city in the state to other cities or other driving environments in Illinois.

“Chicago, based on its size and density is not a good city to compare to other cities in the state,” Alexander explains. “Other comparisons are invalid because its the biggest and densest city in the state. It’s just different here. I think that’s the viewpoint.”

Kubly concurs with Alexander on this point and feels it would be more fair to compare Chicago to larger cities like New York or Philadelphia.

“This is not a city that has an adequate peer in Illinois,” says Kubly. “To compare us to a Naperville or Cairo or Peoria or any other city in the state is not a fair comparison. Any large city would be a better peer. It’s totally different.”

Rear End Collisions Still Pose Safety Risk

But when it comes to rear end crashes, John Bowman, Communications Director for the National Motorists Association, a pro-driver group that has been vehement in its opposition to red light cameras, says Chicago’s increase in rear end crashes at RLC intersections is expected.

“That’s no surprise to us,” said Bowman. “Other studies do show rear end crashes to tend to go up when they (red light cameras) are installed. The reason is drivers become indecisive at red light camera intersections and do not know whether to go through the light or stop.”

Drivers wishing to avoid a ticket will then stop short only to be rear ended by the car behind them according to Bowman.

And while Bowman agrees that right angle crashes typically pose the most danger he says one shouldn’t discount the danger of a rear end collision, who’s car was once totaled after being rear ended.

“Many rear end crashes can be very serious accidents,” says Bowman. “We don’t necessarily want to downplay that.”

Crash Reductions Parallel Overall Crash Trends

Overall Chicago’s 27.7% decline is an impressive number until it is compared to crash data from the Illinois Department of Transportation, which showed a 29.2% decline in total vehicle crashes over the same time period for the entire state.

In essence, the city, with the largest red light camera program in the nation with 191 intersections utilizing this type of enforcement, mildly underperformed statewide numbers reflecting reduced crashes.

In addition, Shah believes state and city numbers showing declines in crashes have been artificially enhanced due to a recent change to state law on how crashes are reported. As of January 1, 2009 accidents that resulted in less than $1,500 in damages were not reported as crashes. Before the threshold change, any crashes resulting in $500 or more were reported. A recent IDOT crash report admits this reporting bias stating, “part of the decline is attributable to this change in the crash reporting threshold.”

This higher damage cost threshold most likely reduced the number of crashes reported at both the city and state level. In other words, this change in how crashes are reported may be making CDOT’s crash reductions look rosier than they seem at least according to Shah’s assessment.

Chicago’s Intersections Getting More Dangerous?

More troubling is that, according to CDOT’s report, the percentage of total crashes occurring in intersections, has increased from 26% in 2006 to 32% in 2010.

“Chicago intersections were more dangerous after red light cameras,” says Shah of CDOT’s data. “(Proponents say) Red light cameras are supposed to have a halo effect on other (non-RLC) intersections. But in 2006 only 1/4 of total crashes were happening in intersections, yet in 2010 nearly 1/3 of total crashes happen at intersections. Chicago intersections are a more dangerous place than they were three or four years ago. If red light cameras were making intersections safer that number would drop.”

City Says Study On Pedestrian Fatalities Shows Safety Gains

In order to further emphasis their point that red light cameras enhance safety, Alexander and Kubly pointed to a recent study of 117 red light camera intersections where CDOT compared pedestrian fatalities for the two years before installation of red light cameras and after. Total pedestrian deaths at those locations dropped from 26 in 2004/2005 to just 11 deaths in 2009/2010.

This particular report has not been made available to the public.

Will Speed Cameras Enhance Safety?

Considering Mayor Emanuel and CDOT Commissioner Gabe Klein keep pointing to the safety gains made by red light cameras to make their case for a robust speed camera program, does Shah think speed cameras will improve traffic safety?

“The effect it (speed cameras) will have is it will not change accident rates,” contends Shah. “But it will bring in a lot of money for the city.”


CDOT Red Light Camera Crash Study

Prof. Rajiv Shah’s Red Light Camera Accident Data Study

Illinois Crash Data 2006-2010

11 Responses to Chicago Red Light Camera Study Shows Mixed Results

  1. GEEK, terriffic article, its balanced, insightful and is a great reference.

  2. Stephen says:

    Also realize that the use of “angles” INCLUDES NON RLV CRASHES!

    Quote: If you look at the PDF: (which we have attached).

    This report listed the ANGLE crashes. But they also listed right next to what the LISTED CAUSE was.


    Interesting eh.

    I added it up.

    If we were to use the “angle crash” claim that the vendors and cities like to spout of, it would show 1 less Angle crash for the 3 approaches in this report.



    Fight the RLC FRAUD!

    Ban the CAMS!

  3. I just attended a meeting on the Spy in the Sky at the Chicago Historical Society. The most discussed were red light and speed cameras. Except for Professor Shaw nobody had the slightest trace of camera facts including the alder woman. What a farce. Naturally, I asked a few insightful education questions they didn’t have answers to.

  4. [...] cameras. It shows, among other outcomes, that one type of crash decreased and another decrease (read the details there). Based on the comments I’m reading here, there, and on EveryBlock, it seems that some people [...]

  5. If enough people called city hall and called their legislators, perhaps the officials would be forced to rethink the whole scam.

  6. Shah’s findings are published on his own blog and do not cite any kind of peer review. As Professor Shah funded the research himself, he states that his analysis did not include a control group and that he didn’t have the resources to look at the full data set. His conclusion states that, “The goal was not to do a comprehensive study of RLCs, but only to ask whether the benefits of RLCs are obvious.”

    Both the Expired Meter, and Professor Shah use the NUMBER of crashes as a measure of safety. Shah’s report does not discuss injury rates at all. His conclusion acknowledges that the number of angle crashes may have decreased, but doesn’t acknowledge crash type and severity as legitimate safety impacts. The Active Transportation Alliance prioritizes human safety over property damage.

    On the June 8th posting titled, Local Professor Raising Hard Questions About Chicago’s Red Light Camera Program, the Expired meter quoted traffic engineer Matt Gauntt, “who has done studies on red light cameras for IDOT in the past,” as saying that “RLC’s change the dynamics of the accident experience, more than they change the overall rate of accidents. You typically have fewer right angle accidents, but you have more rear-end accidents. In some cases, you can show a decrease in the severity of the injuries, but you have more less severe accidents.”

    If it means fewer injuries and deaths, then the Active Transportation Alliance considers “less severe accidents” a victory for health and safety, and those benefits are “obvious” to us.

    None of this sheds any light on how an admittedly incomplete study (criticism) of RLC’s is applicable to the results of a speed camera program.

    Shah’s report:

    Ron Burke, executive director, Active Transportation Alliance

  7. 019 District Cop says:

    Until ATA can convince 100% of its membership to abide by traffic rules, stop signs and stop lights..

    I don’t care what you think.

  8. The ATA doesn’t grasp the fact that the correct amount of yellow time (1 second longer) benefits pedestrians and cyclists too. The ATA totally ignores the real life reduction in violations and crashes experienced by the State of Georgia, 80 and 50 percent respectfully. Until the ATA acknowledge these genuine facts,ignore them for the lobbyists they are.

  9. The Parking Ticket Geek says:


    First thank you for the comments. We very much appreciate the input and the contributions to ongoing debate here.

    I get your point about using the number of crashes as a metric to measure safety. However, to my knowledge, I’m unaware of public City of Chicago data that relates red light camera enforcement to injury rates.

    I would love to see those numbers if they exist. Because I agree, those numbers would shed light on these particular issues.

    However, without those numbers, the best measurement tool available is total crashes.

  10. Dave Sarik says:

    BAN CHICAGO! Let them keep all their damn cameras! Tell Rahm to pay his $57 Million parking meter fines!!

  11. [...] is the red light capital of the US with 191 intersections issuing tickets for red light violations.  There have been some [...]

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