Nationally, the evidence is pretty convincing - red-light cameras generally persuade drivers to be more careful, reducing related crashes and potentially saving lives.
But locally, it is difficult to determine if scores of red-light cameras actually are improving safety as promised, as they simultaneously provide much-needed cash for financially strapped governments.
The Daily Herald, as part of its "Seeing Red" series, has found little substantive evidence of crash reductions at suburban intersections, mostly because cameras have been up for such a relatively short period of time.
Complicating matters, many cameras are going up at intersections where crash rates are low and less dangerous right-turn-on-red violations are high.
As a result, experts say ticket and crash statistics culled from these sites will not provide any definitive picture of whether safety is being improved. Yet, supporters say the cameras work, often citing a consistent reduction in violations at intersections with cameras.
Such disparity only seems to reinforce the perception that red-light cameras are not about safety, experts argue.
"If you look at the data on how these cameras are actually being used, I believe it is largely about revenue and not about safety," said Rajiv Shah, a faculty member at the University of Illinois at Chicago who studies surveillance and red-light cameras. "We all recognize that one of the big reasons it spreads so quickly is that it makes a lot of money while having a veneer of safety."
The Daily Herald revealed this week how the majority of red-light camera tickets issued in most suburbs are for right-turn violations, a practice that can target drivers crawling through a turn who think they are driving safely.
At the same time, many cameras are going up at intersections where there are few crashes related to running red lights. In all, state data shows 20 out of 106 intersections for which information was available have fewer than four crashes a year related to running a red light.
Informed of the Daily Herald's findings, experts have called for better oversight of where cameras are located and how they are ticketing the public to ensure safety is the true goal. But at the same time, they say those findings make it hard to determine if improved safety is even demonstrable in several cases.
University of Illinois engineering professor Rahim Benekohal said the focus on right turns and placement at low-crash intersections will leave researchers grasping for ways to measure any resulting safety improvement.
"Clearly a lack of standards is going to bring a diversity of approaches and interpretations," he said.
Still, some crash data does exist, however inconclusive.
A Daily Herald compilation of crash data at 10 near-West and South suburban intersections where cameras have been up for at least a year shows a 34 percent decrease in crashes across the board, from broadsides to rear-ends.
The data, which is from early evaluations ordered by the state, compares crash data from one year before the installation of the camera and from the first year it was operational.
Such information was not available for nonstate roads. Cameras in the West, North and Northwest suburbs have yet to be reviewed by the Illinois Department of Transportation.
In total, the number of crashes fell to 50 from 76 at the 10 intersections, which are in the suburbs of Dolton, Berwyn, Schiller Park, Melrose Park, South Chicago and Hickory Hills.
The statistics show a 7 percent slide in rear-end crashes, 54 percent drop in broadside crashes, 60 percent cut in turning crashes and 22 percent decline in other types of crashes.
But a closer look at the numbers reveals they can't be used to make a definitive statement on whether the cameras improved safety, experts say. That is because comparing one year to the next is not a good statistical assessment, and several of the intersections had low crash rates.
Six of the 10 sites had four or fewer crashes likely related to running red lights in the year before the cameras were installed.
For example, at two Schiller Park intersections with one broadside crash a year before red-light camera monitoring, one site saw an increase to two and the other saw a decrease to zero.
Researcher Richard Retting, who has written numerous national studies on red-light cameras, said such low crash figures cannot alone provide an indication of change in overall safety.
"You can't get much smaller than one or two," he said.
Larry Decina, a researcher with Pennsylvania-based TransAnalytics who compiled a 2007 worldwide literature review of red-light camera studies, agrees. "You can't really evaluate crashes when there are just a few of them," he said.
Aside from the state evaluations, locally compiled crash comparisons for one suburb was available. The intersection of Randall Road and Acorn Lane in Lake in the Hills showed an increase to 40 crashes in the camera's first year, compared to a three-year average of 38 before.
One of the added crashes was a broadside, usually attributable to running a red light and often the most dangerous. There were no broadside crashes in the three previous years.
The camera issued 1,512 tickets in the time period from January 2008 to January 2009.
Tickets = safety?
Lake in the Hills officials concluded in their official report that a one-year review didn't provide enough data to indicate if the camera is having a safety impact.
But the study does point to a reduction in violations as a sign safety is improving even if it is not connected to a reduction in related crashes. The second half of 2008 saw a 62 percent decrease in tickets compared to the first half.
"There was a significant drop in red-light violators that would show the program is working," concludes Deputy Police Chief Dave Brey.
Across the suburbs, police chiefs are coming to the same conclusion: They see violation rates drop after the camera goes up and they declare safety is improving.
"We have seen the violation numbers decrease and ultimately that is our goal," Wayne Police Chief Dan Callahan said.
Wayne's lone camera at busy Route 59 and Smith Road is at a site where, on average, about three crashes likely caused by running red lights occur yearly. Wayne sent out 127 tickets at that intersection in the first month of operation, November. In March, the latest data provided, 100 tickets were issued.
A reduction in violations is an acceptable measurement when crash data is not available, experts say. However, when most of the violations are for right turns on red - as is the case in Wayne and most suburbs - that may not directly equate to safety, Benekohal said.
"I'm not sure how much of a strong correlation you can find between a couple feet of distance versus safety," he said, regarding drivers who crawl slowly through a turn or do stop after the intersection's white line. "The most crystal issue is whether the driver is negotiating that curve as safe as possible or if that driver is neglecting the other vehicles and pedestrians."
While local data on the impact of red-light cameras is limited, national data seems abundant and clear.
"The solid research is very consistent," said Russ Rader, spokesman for the Insurance Institute of Highway Safety, an insurance industry group that champions the use of red-light cameras. "The studies, on average, find that red-light cameras reduce red-light running."
Overall, studies have found a decrease in the most dangerous crashes associated with running red lights - broadside and turning wrecks - by an average of 20 percent to 30 percent. The studies have also indicated a slight increase in rear-end crashes, apparently brought on by more vehicles stopping earlier in the traffic light's yellow cycle to avoid a ticket.
For example, a 2005 study by the U.S. Department of Transportation on 132 intersections across the country with cameras found a 25 percent reduction in broadside crashes and a 15 percent increase in rear-end crashes.
The impact on safety could be significant, considering red-light running is blamed for up to 800 deaths a year across the country and more than 160,000 injuries.
But national data is not available on whether the intersections getting red-light cameras had low crash rates to begin with, or whether the cameras were predominately issuing tickets for right-turn-on-red violations.
As for Illinois, there is no set plan in place for an across-the-board review of red-light cameras' effectiveness. Red-light camera installation is left under Illinois law to the sole discretion of local governments, unless county or state roads are involved. So, no single agency has oversight of all the cameras and none are charged with a complete review of their impact.
State officials say they are collecting data and they hope to do a broader study in the future. Yet, no solid plans remain in place to do so.
"I think that is part of the intent," said Steve Travia, traffic operations chief for the Chicago area. "But I don't think we have gotten to that point yet."
Data: State plans broad study in the future