Red Light Camera News Professor Shah's: RLC claims of "‘Safety” is just lip service, they just want revenue"
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June 8th, 2010
Local Professor Raising Hard Questions About Chicago’s Red Light Camera Program
Data Shows 6% Increase In Crashes At RLC Intersections
Something just isn’t adding up.
At least that’s what Professor Rajiv Shah’s research seems to show.
Prof. Shah’s analysis of Chicago’s red light camera system seems to indicate that perhaps the devices don’t live up to the claims they actually decrease traffic accidents. And quite possibly, according to Shah’s findings, the cameras may actually increase accident rates at the intersections where they’re in place.
“I’m very surprised,” explained Shah. “I really expected to see a decrease in accidents at red light camera intersections. Despite what the city says there doesn’t seem to be any safety difference here.”
Shah is an adjunct professor at the University of Illinois-Chicago. Shah, earned his BA at the University of Nebraska and while he was earning his PhD in Communications from University of Illinois-Urbana-Champaign in 2004, he first became interested in the subject of what he calls “smart cameras”. Shah also curates a website on the subject called the Smart Cameras Blog. His interest in smart cameras is what ultimately led him to begin closely looking at Chicago’s red light camera program.
People Driving Less, Accidents Decreasing In Chicago
As part of his recent research, Shah wanted to account for any outside factors when analyzing the alleged effects of RLCs on crashes. One of the things he studied was Illinois Department of Transportation driving and accident data for Chicago roadways and specifically at Chicago traffic signals.
The good news is IDOT data seems to indicate a steady decline in accidents between 2001 and 2008 (that is partially connected to a decrease in total miles driven annually), with total crashes decreasing by 21% within that time frame. However, despite this decrease in auto accidents citywide, the percentage of accidents occurring at Chicago’s city traffic signals has remained constant at around 25% from 2001 to 2008–showing no similar decrease.
“If people were driving more carefully at traffic signals, it would be expected that accidents at traffic signals would become relatively rarer,” explains Professor Shah. “The results here suggest that traffic signal accidents are holding relatively constant. This also suggests the red light cameras are not having a halo effect because accidents are not dropping throughout the city at traffic signals.”
In addition, Shah’s study of IDOT numbers shows a 5% decrease in right angle crashes at all city traffic signals, a number Shah sees as very significant. In addition, there seems to be a related decrease in the severity of injuries at intersections.
Data Shows Increase In Crashes At RLC Intersections
However, when Shah reviewed IDOT data for 39 RLC cameras http://tables.googlelabs.com/DataSource?dsrcid=170706 installed at intersections between 2006 and 2007, he found some shocking results. Professor Shah looked at all crashes from exactly one year before each camera was installed through one year after installation.
According to the data, despite impressive decreases in accidents at signalized intersections city wide, the total number of crashes at the 39 RLC intersections studied http://tables.googlelabs.com/DataSource?dsrcid=170706 , rose from 1118 collisions the year before each camera’s installation to a total of 1192 for the year each RLC was in use–or a 6% increase in accidents.
Traffic engineer Matt Gauntt, who has done studies on red light cameras for IDOT in the past, is not surprised by Shah’s results.
“Many people have tried to claim a ‘halo effect’, says Gauntt. “However, I don’t take a tremendous amount of stock in those reports. 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.”
CDOT Challenges Professor’s Conclusions
The City of Chicago, which saw $63 million in fines from red light cameras last year, strongly challenges Professor Shah’s findings and is currently compiling the results of their own study of red light camera effectiveness which seems to show Chicago streets are the safest they’ve been in years.
“There is no question that in the city of Chicago drivers are safer because of red-light enforcement,” said Brian Steele, spokesperson for the Chicago Department of Transportation. “What we’ve seen thus far in our preliminary results is a 20% reduction in right angle crashes at intersections that have red light cameras and a 10% reduction in overall crashes.”
Steele believes part of the difference in results has to do with how IDOT and CDOT define the length of an intersection. CDOT defines the intersection 25-50 feet from the traffic signal, while IDOT will use measurements of 150-300 feet from the middle of the signal.
“IDOT treats data differently than the city does,” explains Steele. ”For example, IDOT may classify an accident as intersection-related when it in fact occurred at mid-block…Additionally, in past years IDOT, for purposes of its analysis, only looked at crashes that were above a minimum dollar amount of damage ($1500 I believe). Chicago looks at all crashes, and city numbers are based on actual police reports filled out at the time of a crash.”
But Shah contends an earlier study conducted by the Office of Emergency Management and Communications (the department previously in charge of the city’s RLC program) on red light camera effectiveness demonstrated no clear impact of the cameras on safety. In comparing 10 control intersections against 10 RLC intersections over a year’s time, the city saw only mild improvement in safety at the camera controlled intersections according to Shah’s analysis. The control group showed a 3.76% decrease in crashes, while the RLC intersections showed a 5.31% decrease–or a mere 1.5% difference.
“This suggests a very small benefit for the red light cameras and is a much smaller figure than the city claims,” says Shah contending the decreases the city claims are statistically insignificant.
Unsurprisingly, the results from Shah’s research make the professor critical of Chicago’s red light camera program.
“What the city is telling us is not true,” says Shah. “It’s obviously not true that accidents are not going down at camera intersections. It shows there’s really a question mark on the effectiveness of these cameras. ‘Safety” is just lip service, they just want revenue
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