Red Light Camera missing link found?

Guy Midkiff


My Alma mater, Texas A&M University, recently issued the following report on red light camera efficacy:


by Troy D. Walden, Ph.D.

These “scientific findings” presented by Dr. Walden have become the missing link, the piece de resistance, the eureka piece for local and state municipalities looking to desperately justify the relentless on slot of red light cameras.

“Because any study where a single team plans the research, carries it out, supervises the analysis, and writes their own final report, carries a very high risk of undetected bias. That risk, for example, would automatically preclude the validity of the results of a similarly structured study that tested the efficacy of a drug.” Michael Crichton

The 80th Texas Legislature enacted House Bill 1052 and Senate Bill 1119 giving local communities the authority to install red light camera enforcement systems. The Texas Transportation Code requires the Texas Department of Transportation to annually publish the reported collisions that occur at local community intersections that are monitored by red light camera enforcement systems.

Executive Summary:

This Based on the pre and post-installation crash data, there were 586 annualized collisions across all intersections. In contrast, 413 annualized crashes were reported during the same time period following installation which evaluation considered 56 separate intersections in the data set. Each community reported pre and post-installation crash data that was annualized for a 12 month period of time resulted in an average decrease of 30%.

Let me make it clear, I am not a scientist. My formal education was in economics with the requisite courses in quantitative analysis and statistical methodology.

Even as a layman, I have substantial problems with this scientific study. I would like to begin by applying the Crichton logic to Dr. Walden’s findings. Michael said this about scientific methodology, as he was giving scientific testimony, regarding global warming:

“Science is nothing more than a method of inquiry. The method says an assertion is valid—and merits universal acceptance—only if it can be independently verified. The impersonal rigor of the method means it is utterly apolitical. A truth in science is verifiable whether you are black or white, male or female, old or young. It’s verifiable whether you like the results of a study, or you don’t.”

Clearly, this study was motivated by political forces hell-bent on validating red light cameras. Politicians are under enormous pressure to prove the virtue of the cameras. They have relied repeatedly on studies that were contaminated by corporate influences such as: Red Light Camera Companies drive to turn a profit, same for Insurance Companies and same for municipalities looking to add revenue to their general funds.

Sadly, this study shows many of the characteristics that render the results useless. The first hint can be found from the study generator, the Texas Legislator. The legislator has made their bias clear on the matter and can explain the motivation to short-change many of the methods used in statistical determination. Also, please pay particular attention to the sampling data. Sample sets consisted of 12 month annualized reports generated from 56 sites. Small sample sets are notorious for their “noisy” determinations.

By way of comparison, researchers at the North Carolina Urban Transit Institute were unsatisfied with the overly simplistic methods used in prior insurance industry funded studies of the effects of red light cameras on accidents. So they conducted a U.S. Dept. of Transportation funded study that looked at a 57-month period and accounted for dozens of variables such as weather and traffic ignored in previous studies. All told, 17,271 observations went into their conclusions.

Mark L. Burkey, Ph.D. and Kofi Obeng, Ph.D., concluded: “The results do not support the view that red light cameras reduce crashes. Instead, we find that RLCs are associated with higher levels of many types and severity categories of crashes.

The graph, found on page 2 of the Burkey-Obeng study shows a clear positive trend in the decrease in injuries caused by red light running in Florida. That data points start at about 50 per 100,000 in 1995, reducing to about 34 by 2006. To lay claim to the last 12 months of this graph and conclude red light cameras were the miracle cure is beyond ridiculous

[CORRECTION 1/4/09: “You suggest that we discussed data in Florida in the mid-1990’s.  Our data was in NC in the 2000’s.” Dr. Mark L. Burkey]

Why is there such a seismic difference between Burkey-Obeng and Walden? One can only guess. To be sure, though, the sample sizes used by Burkey & Obeng dwarfed the A&M study.

[And now a moment of silence: “Facts do not cease to exist because they are ignored.” Aldous Huxley]

If you want refined and accurate statistical results, it has long been understood by scientist that robust sample sizes combined with numerous confounding variables, will paint a true picture.

Finally, accidents at intersections can be broken down into those that are and are not sensitive to Red Light Cameras. Those that are in a rush and try to beat the red are sensitive to RLC’s and for those very few, RLC’s will no doubt have a deterrent affect. Drivers that cause the vast majority of intersection incursions, though, are not sensitive to RLC’s. They include: Those that misjudge time versus distance, drivers that don’t see the signal, and those that are impaired.

But the best and most persuasive argument against Red Light Cameras is what is known as countermeasures.

Such measures should include:

* The adoption of a national standard and uniform code for determining yellow length intervals. (In my city, the approach speed is 45 mph and the yellow light interval is 3.0 seconds. the 2003 TN Traffic Design Manual recommends 4.5 seconds.)
* Similar standards for all red intervals.
* Reducing approach speeds.
* Intersection re-engineering such as coordinated signals and improved marking such as decision point markings.

If your community jumps to Red Light Cameras before they even consider counter measures, don’t be fooled into thinking it is for safety.

Guy Midkiff

Published in: on December 8, 2008 at 11:25 pm  Comments (3)  

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  1. From the to the Houston Chronicle re: RED-LIGHT CAMERAS CUT WRECKS 30%
    You aren’t likely to be swayed by the facts, but the TxDOT study didn’t prove anything, as mentioned in the disclaimer that you hastily dismissed. Accidents are down everywhere — around the entire country — because traffic volumes are down.

    Accident rates are directly correlated with traffic volume because more cars on the road mean more exposure to risk. You can control for this and similar variables like weather by comparing the performance of camera-monitored intersections to non-monitored intersections. But TxDOT didn’t do that, either. In fact, they didn’t even mention this fundamental omission in the summary. Why not?

    Instead, what you get is a report based on a limited set of cherry-picked, self-reported data. Each city pumped in data designed to make its program look as good as possible. The results were, as you imply, predictable.

    Proper studies with control groups that account for regression to the mean have come to quite different conclusions, as can be found here:

    These aren’t the propaganda studies written on behalf of the groups that profit from red light camera — namely the insurance industry (California in Arizona have license points) and municipalities. That’s why they don’t come to the conclusion that you desire.

    Of course, there’s another problem with self-reported data. According to the British Medical Journal — hardly a source with political bias — it appeared that police forces reported fewer road casualties than they should have given the actual rate of hospital admissions. This manipulation, of course, made speed cameras look better. Read for yourself:

    BMJ report:

    But I’m sure that the executive summary of an unscientific report will make you feel safer.

  2. From the Blog: Houston Press

    Lawyer To Sue To Get That Secret Red-Light Camera Study
    Fri Dec 12, 2008 at 10:45:46 AM
    redlite121208.jpgHouston civil rights attorney Randall Kallinen says he is going to sue the city for refusing to hand over any information whatsoever concerning a red-light camera traffic-safety study conducted by a Rice University professor.

    Kallinen says he talked to the study’s author, Professor Robert Stein, and knows the report is completed and shows data that is “in direct odds to” a Texas A&M study recently released stating that red light cameras reduce accidents by 30 percent across the state.

    Kallinen has twice requested the report under the Texas Public Information Act, and says he has twice been denied. Patrick Trahan, spokesman for Mayor Bill White, has said the report is still in draft form, meaning technically the city is not in possession of the report, and therefore cannot release it. Trahan also told Hair Balls Tuesday he expects the city to release the report “in the next couple of days.”

    Still, on Wednesday Kallinen says he received a letter from the city saying it is forwarding his request to the Attorney General for a ruling on whether it has to fork over the report and related information.

    “The law unequivocally states that draft reports are public records and documents in the hands of people contracting with the city are public record,” says Kallinen. “So, there’s no exception for the report or the other documents I’ve requested that they won’t give me, such as the contracts to have the study done or any emails. It’s hard to believe there’s not one email about this study. But they won’t give me nothing.”

    Kallinen says he will file the lawsuit as quickly as possible.

    “If people do something incorrect,” he says, “you shouldn’t wait too long until there’s a consequence. The people need to know, for their own safety, the results of the completed or draft Rice University study so they can make a decision whether or not to continue the use of the red light cameras in Houston.”

    — Chris Vogel


    The Chicago Tribune’s February 7th editorial focused on the CTA being “encouraged” by the driver’s union to pay their member’s 1,200 red light camera tickets for a total of about $120.000! The CTA deemed the tickets to be a “bureaucratic nuisance” even as the rest of the public has to pay whether you own a car or not! It’s not inherently fair nor is it legal to hold one group of persons “above the law” while indiscriminately punishing another equal group for the same offenses. Citing CTA schedules and passenger safety excuses for running red lights doesn’t is no justification.

    Hundreds of millions in ticket revenue is just too tempting of a windfall for the city to ignore. Especially when it’s done under the “color of authority”, the color red. The entire city has become one enormous red light district. Traffic signals have historically been set to established national traffic engineering standards. The accepted rules of the Manual on Uniform Traffic Control Devices, the U.S. Department of Transportation, Federal Highway Administration, and the Institute of Transportation Engineers were established to promote safety, but they aren’t acknowledged in Chicago! Other city’s traffic experiences have shown accident increases after their respective red light camera installations.

    Red light cameras serve obediently 24 hours a day dutifully snapping pictures of license plates and converted at the “light speed” into a constant revenue stream that beats to the pulse of the politician’s pocketbook. What a golden thing it is to behold. The robocops have no regard for real traffic requirements such as the 85th percentile speed, approach velocity, forward head room, visual safety perception, mechanical maladies or radio frequency interference.

    Chicago joins the growing list of maniacal metropolises that include Chattanooga, TN, Dallas, TX, Springfield, MO, Lubbock, TX, Nashville, TN and Union City, CA that have been caught grossly cheating their drivers by local media using short-timed yellow traffic lights. News outlets shined the light of truth and turned the cameras back onto this seditious and dangerous practice to allow the cities to balance their particular budgets. Subsequent lengthening the yellow light timing results in fewer violations, less accidents, safer roads far less cost.

    Ticketed drivers can appear in front of a trained ticket clerk, but they soon find out that their “administrative” red light ticket challenges are stiffed by the political provisions of the ordinance. While these citations don’t currently add points to driver’s licenses, IT “CONVENIENTLY OUTLAWS” ANY LEGAL OR ETHICAL CHALLENGES. If drivers want to appeal their cases to a higher court another charge of $95 for a filing fee plus a mandatory downtown appearance. The city fathers figured the vast majority of drivers can’t afford the time coupled with almost no chance of winning to justify the effort.

    Apparently the laws of physics, motion or logic don’t apply within the windy city. The city has determined that all vehicles, drivers and intersections are identical by their very nature so a single three second yellow light timing standard is all that is needed, when actually it is barely the federal minimum. The city knowingly takes no notice of real world factors such as driver response times, vehicle size, inertia, road or visibility conditions that are recommended by traffic.

    Because accepted traffic signal engineering practices are ignored the city it consciously and directly participates in ongoing cases of “spontaneous legal entrapment” each time any of the stop lights turn red. The city stifles the increased rear-end accident facts after red light camera installations in many other cities. “The city that works”, makes drivers work for the department of revenue and leaves the city politicians with dirt on their hands!

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