Chicago's red light cameras fail to deliver the dramatic safety benefits long claimed by City Hall, according to a first-ever scientific study that found the nation's largest camera program is responsible for increasing some types of injury crashes while decreasing others.
The state-of-the-art study commissioned by the Tribune concluded the cameras do not reduce injury-related crashes overall — undercutting Mayor Rahm Emanuel's primary defense of a program beset by mismanagement, malfunction and a $2 million bribery scandal.
Emanuel has credited the cameras for a 47 percent reduction in dangerous right-angle, or "T-bone," crashes. But the Tribune study, which accounted for declining accident rates in recent years as well as other confounding factors, found cameras reduced right-angle crashes that caused injuries by just 15 percent.
At the same time, the study calculated a corresponding 22 percent increase in rear-end crashes that caused injuries, illustrating a trade-off between the cameras' costs and benefits.
The researchers also determined there is no safety benefit from cameras installed at intersections where there have been few crashes with injuries. Such accidents actually increased at those intersections after cameras went in, the study found, though the small number of crashes makes it difficult to determine whether the cameras were to blame.
The finding raises questions about why the city installed cameras in so many places where injury-causing crashes were rare — nearly 40 percent of the 190 intersections that had cameras through 2012, the Tribune found.
"The biggest takeaway is that overall (the program) seems to have had little effect," said Dominique Lord, an associate professor at Texas A&M University's Zachry Department of Civil Engineering who led the Tribune's study.
"So the question now is: If we eliminate a certain type of collision and increase the other and overall it stays the same, is there an argument that it is fair to go with the program?" Lord said. "That is a question that I cannot answer.
"Just the elected officials can answer for that."
Emanuel declined interview requests. His top transportation experts acknowledged flaws in the city's statistics but said the Tribune study reinforces their own conclusion that cameras are helping.
Chicago Transportation Commissioner Rebekah Scheinfeld said the city has never attempted a deep examination of the effectiveness of the largest automated enforcement program in the country, which has grown to more than 350 red light cameras and raised more than $500 million in $100 tickets since 2002. She said the Emanuel administration, now in its fourth year, is attempting to fix a long-standing lack of oversight.
"So certainly, the study presents an interesting argument, something that we will be considering moving forward," Scheinfeld said. "But the fact is, the important thing I want to make sure that we get across here is that there are less deaths out there, there are less injuries out there and we are very encouraged by that."
Several national traffic experts consulted by the Tribune called the study a valid examination that largely mirrors the results of similar scientific efforts conducted around the country that found moderate decreases in T-bone crashes coupled with increases in rear-enders as drivers hit the brakes to avoid camera-generated tickets.
The study findings also dovetail with the Tribune's examination of how short yellow light times at Chicago's traffic signals raise the stakes for drivers.
Prompted by Tribune reporting, Emanuel officials recently admitted to the city inspector general that they had quietly dropped the threshold for what constitutes a red light camera ticket, allowing the tickets even when cameras showed a yellow light time just under the three-second federal minimum standard. That shift earlier this year snared 77,000 more drivers and $7.7 million in ticket revenue before the city agreed to change the threshold back.
Now the Tribune has learned that Chicago's long-standing reliance on using the lowest possible yellow light time under federal guidelines is out of step with other major cities in the country and a growing body of research that suggests short yellows and red light cameras are a dangerous combination.
"Of course that is going to lead to more accidents, especially rear-end accidents," said Timothy Gates, a Wayne State University associate engineering professor whose research is being used to set new nationwide guidelines calling for longer yellow lights.
As recently as October, transportation chief Scheinfeld appeared before a City Council hearing to defend the red light camera program armed with poster boards boasting a 47 percent reduction in right-angle crashes at camera-equipped intersections and a 22 percent drop in all types of injury crashes.
Those numbers are from a report on the city's website with a list of crash statistics at each of the red light camera intersections from 2005 and from 2012.
"Since being launched more than a decade ago, the red light camera program has been a critical part of our efforts to improve the safety of our streets," Scheinfeld told the assembled aldermen. "The most recent crash statistics available from the state show that at intersections with red light cameras, the number of dangerous T-bone, angle crashes decreased by 47 percent between 2005 and 2012."
Given those numbers, the effectiveness of red light cameras would be difficult to dispute. But a half-dozen traffic engineering experts interviewed by the Tribune all agree that simple before-and-after comparison is not an effective measure. It doesn't account for changes in traffic flow because of the economic recession, or the improved safety of automobiles or any number of factors that have brought down crash numbers throughout the nation.
And most important, experts say, it doesn't account for any significant changes in the way accidents are reported to state transportation officials.
For instance, in 2009 the Illinois Department of Transportation changed the threshold for reporting property damage accidents to $1,500 in damage from $500, a rule change that prompted accident reports statewide to plummet by nearly 30 percent. That change alone renders the city's safety claims invalid, experts say.
"The city's study is worthless, making no adjustments for any potential bias," said Joseph Hummer, professor and chairman of civil and environmental engineering at Wayne State in Detroit. He also noted that, for some sites, the city used 2005 data in the "before" section of its analysis even though the cameras had been installed there in 2003 and 2004.
Scheinfeld said in an interview last week that the city's safety claims are based on "more basic," nonscientific comparisons of crash statistics. She said the state transportation department statistics are "still the best information that we have, and we acknowledge they have made that change in their reporting methodology, and it would have some impact on those numbers, but we don't know exactly what impact."
Scheinfeld said she was aware of the flaw in the data when she presented the city's safety claims to aldermen. The 47 percent figure was still posted on the city's red light camera Web page at publication time for this report, but after talking to the Tribune, officials added a disclaimer about the change in IDOT accident reporting.
But she disputed the notion the city has used inflated statistics to mislead the public about the unpopular program.
"We weren't saying that those reductions are all attributable directly to, or only to, the installation of red light cameras," Scheinfeld said. "What we are saying is that we are seeing these trends which are very encouraging at those locations where we have red light cameras."
Ald. Anthony Beale, 9th, chairman of the council Transportation Committee, said the city's numbers come as no surprise: "Those numbers the city uses have never made any sense. Of course they are skewing the numbers."
"That program needs to be stopped. It needs to be frozen to give us time to re-evaluate everything," Beale said. "This is just more proof that this entire program is strictly to generate revenue and always has been."
The Tribune study
In an effort to assess the program's effects more realistically, the Tribune collaborated with Lord and another well-known researcher from the Texas A&M Transportation Institute, Srinivas Geedipally, to conduct an analysis using the latest scientific tools.
The $14,000 study used data gathered by the Tribune under the guidance of traffic safety experts around the country. The Tribune's work was also approved by Lord and Geedipally, who have published dozens of analytical papers on traffic safety, including red light camera systems, and worked as consultants to state and federal government.
The Chicago study by Lord and Geedipally acknowledges that the number of injury-causing accidents decreased at intersections after red light cameras were added, but it also notes that this simple comparison fails to account for other factors that affect a region's crash rates, such as changing economic conditions.
To determine the impact of red light cameras specifically, the researchers used a statistical technique called the empirical Bayes method that is commonly employed to evaluate traffic safety interventions. By analyzing data from intersections without red light cameras, they could predict how many crashes would have occurred at camera intersections if the equipment had not been installed.
The study included 90 of the 190 intersections in Chicago where cameras were operating during the study period. All 90 used in the study were four-leg intersections where cameras came online between 2008 and 2009. The Tribune also collected detailed Illinois crash data at each intersection for three years before and three years after the cameras were installed, as well as similar information for a control group of 59 intersections never equipped with cameras.
Lord and Geedipally used that data to conduct their analysis, the largest such study conducted on a single red light camera program in the United States.
The study results showed red light cameras are responsible for "a non-significant increase of 5 percent in the total number of injury crashes, a statistically significant reduction of 15 percent in angle and turning injury crashes, and a statistically significant increase of 22 percent in rear-end injury collisions," the authors wrote.
In raw numbers at the 90 intersections included in the study, the researchers concluded the cameras prevented as many as 76 right-angle crashes and caused about 54 more rear-end injury crashes. The study said that without the red light cameras about 501 angle crashes would have occurred and only 425 were reported. It also said that there were 296 rear-end injury crashes, and there would have been only 242 had the cameras never been installed.
There were 1,064 crashes reported in the three years after the 90 intersections were "treated" with red light cameras, the study noted.
"The analysis results show that if the treatment had not been used, the expected number of the crashes would have been 1,016 crashes," the study said. "In other words, it is estimated that RLCs (red light cameras) increased the crashes by 5 percent."
Because that 5 percent increase was considered within the study's margin of error, Lord and Geedipally said the increase might have happened just by chance.
The Tribune study did not address the cameras' impact on fender benders where no injuries were reported.
The researchers said similar crash patterns were also found at the control intersections that had no cameras, suggesting drivers fearing a $100 fine may be changing their behavior at intersections throughout the city. They said more research would be needed to say definitively whether such a "spillover effect" exists.
"It may be possible that drivers changed the manner they approach and travel through all the signalized intersections located within the City of Chicago," the study says, adding that science on the theory of spillover effects is inconclusive.
The results of the Tribune study closely track those of a 2005 analysis of red light cameras commissioned by the Federal Highway Administration that used identical scientific methods to analyze 132 intersections in seven cities throughout the country. That study found a 16 percent decrease in right-angle injury crashes and a corresponding 24 percent increase in rear-end injury crashes.
The federal study went even further and assigned dollar damage estimates to the various kinds of crashes to conduct a cost-benefit analysis between rear-enders and the typically more dangerous T-bone crashes.
"The economic analysis examined the extent to which the increase in rear-end crashes negates the benefits for decreased right-angle crashes," the 2005 study concluded. "There was indeed a modest aggregate crash cost benefit of RLC systems."
The Tribune researchers also suggested that Chicago could reap much better results if it shut down about 40 percent of its cameras, located in about 75 intersections throughout the city where crash rates were lower to begin with. Of those intersections, cameras were removed from eight before the completion of the Tribune study.
"When intersections experiencing fewer than 4 injury crashes per year are considered, there is a significant increase in all crashes by 19 percent after the installation of RLCs," the study found.
"They are not doing what you would expect," Geedipally said. "You can make an argument based on those two numbers, over four (injury crashes) you see a benefit but less than four you don't see that benefit. So is it worth putting the cameras at those locations? That's a question you may want to ask the mayor."
Other experts said the Tribune findings make it clear that nothing less than a complete re-examination of the city's program can solve the problems.
"My feeling is that they should conduct a re-evaluation of every intersection where a camera is installed and look at the crash numbers for each of them," said Raghavan Srinivasan, a senior transportation research engineer at the University of North Carolina Highway Safety Research Center. "All the research shows that the higher the rate of right-angle crashes to begin with, the more benefit the cameras provide."
Scheinfeld and her deputies said the city will use the study in its annual assessment of the camera program.
"You have offered a different perspective, a different method, a different data set looking at slightly different crashes," said David Zavattero, the city's deputy transportation director. "I think we are going to take that very seriously and look at some of those same questions."
The findings are the latest in a series of Tribune investigations beginning in 2012 that have exposed corruption, failed oversight and unfair enforcement in Chicago's program, once held out as a model for automated traffic enforcement.
In the wake of Tribune revelations, the city's contractor was fired, that company's top executives were ousted and federal prosecutors charged a former City Hall manager with taking up to $2 million in bribes from the former CEO of the company, Redflex Traffic Systems, to build its Chicago business into the largest automated traffic enforcement program in the country.
Last week, a former Redflex consultant pleaded guilty to funneling bribes to that manager, John Bills, as part of an alleged scheme that earned the men at least $1,500 for every new red light camera installed in the city.
While the alleged corruption largely dates to the administration of former Mayor Richard M. Daley, Emanuel has defended the red light program as a much-needed safety measure and used it to justify his launch of speed cameras.
Following a series of Tribune stories this past summer that documented how thousands of drivers were tagged during unexplained ticket surges at malfunctioning red light cameras, the city inspector general reported that both the Daley and Emanuel administrations could not document how and where they chose to place cameras, abdicated their responsibility to ensure the camera system was working properly and instead focused on keeping the cameras rolling.
In response, Emanuel promised to improve oversight, played down the significance of the findings and sought to refocus public attention on safety benefits.
"The red light camera operates here like it operates in other cities," Emanuel said in July. "And it has reduced accidents, and dangerous accidents, which are the sideswipes that happen. So it has worked on the safety side, but to be an operative system, it must have the public trust."
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