The folks at the Frum Forum have retracted their article in opposition to red light cameras, saying “they work.”

I don’t actually disagree with that. And honestly, if done in conjunction with other things, such as longer yellow lights and preferably a light timer, I would support them. There are two counterarguments to lengthening yellow lights. The first is that it causes all kinds of traffic problems because of the “very specific formula they use.” Which is interesting, because they don’t seem to have a problem shortening the duration of yellow lights. The second argument is that people adjust to the shorter duration and it doesn’t make any difference. Here’s a quote:

We did notice immediately that the number of violations dropped significantly. But within four days what we found was that people had changed their driving habits. They knew that they had extra time. And it was virtually the same number of red light runners occurred within 4 or 5 days after we changed that light.

Does this jump out at anybody else? Four or five days? How many people are going to even notice such a change, much less adapt to it? At least some drivers probably haven’t even driven through the intersection during these five days. It would have been more credible if he’d said “within six months” or something. Five days? That’s just… not credible.

And I don’t have to, because it’s been studied. The National Motorist Association, which is critical of red light cameras, has a host of studies on the subject, including one in Fairfax, Virgina:

Skrum continued, “Fairfax County records show that ‘events,’ red light violations, captured by the camera fell from an average daily rate of 52.1 per day before the yellow time increase to just 2 per day afterwards, a reduction of 94 percent.

“Fairfax County records also show that citations being issued dropped to just 0.82 citations a day on average during the 67 days after the yellow time was increased.

“This camera was activated February 8, 2001 by Lockheed Martin under an agreement with Fairfax County. The Virginia Department of Transportation is responsible for operating these signals. The decision to install a red light camera at this intersection confirms that this intersection was considered a location of serious violations with increased potential for accidents.

I could actually be convinced that it takes more than 67 days for people to adapt… but they’re already on the record as saying “4 or 5,” so there you go. Now, the NMA is a biased source. But what about the Texas Transportation Institute? They determine the following:

A before-after study is described and the resulting data used to quantify the effect of increasing the yellow interval on the frequency of red-light violations. Based on this research, it was concluded that: (1) an increase of 0.5 to 1.5 s in yellow duration (such that it does not exceed 5.5 s) will decrease the frequency of red-light-running by at least 50 percent; (2) drivers do adapt to the increase in yellow duration; however, this adaptation does not undo the benefit of an increase in yellow duration; and (3) increasing a yellow interval that is shorter than that obtained from a proposed recommended practice published by the Institute of Transportation Engineers (ITE) is likely to yield the greatest return (in terms of a reduced number of red-light violations) relative to the cost of re-timing a yellow interval in the field.

Both #2 (highlighted) and #3 are important. If we are going to use red light cameras, part of the package has to be following the proposed recommended practices of the ITE or independent civil engineers of some sort.

There are two important things to note about the TTI. First, they have also studied red light cameras and have determined that they are effective (even taking into account the increase in rear-enders). So, unlike the NMA, they are not saying anything about yellow lights in order to further an argument about red light cameras. Second, the original article cites the authority of… the TTI… in making its case.

So what have we learned here? We’ve learned that maybe there is reason to believe that we should institute red light cameras. We’ve also learned that there might be alternatives. But really, these alternatives are not mutually exclusive. We can do all of them. And if the goal were public safety, we would do them as a matter of course.

Above I mention light timers. By which I mean the thing they have on crosswalks that tell you how much time you have before the light changes color. The lazy cynical response to this is that it will just encourage more people to wait to the wire. This assumes, however, that everybody who runs red lights does so intentionally. I don’t think that’s the case. I think the ambiguity of not knowing how long you have causes people to ramp up because by the time the light turns yellow, they don’t know how long they have to get through, and they weren’t ready for the yellow light to begin with. I’d happily accept the results of a study on the subject, though, provided that it’s by an organization like the TTI or ITE rather than by someone with a real skin in the game.

Category: Road

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4 Responses to GreenYellowRedFLASH

  1. Kevin says:


    In Houston, where I live, the residents voted to get rid of the red lights cameras. I worked with the organizers of the ballot initiative, both professionally when I was at my prior firm, and as a volunteer, after I left. One of the very interesting things that the ballot organizers noticed was that there were no red-light cameras in poor (i.e., minority) neighborhoods. They got a ton of mileage out of this with the minority community. I have a very low opinion of the red-light camera companies. Personally, I’m like you. I wouldn’t mind the cameras so much if they were part of a package of intersection reforms, primarily lengthening the duration of the yellow light. Another feature that I would support is to only impose a penalty after the light’s been red for a specific length of time, say 0.5 seconds. This way those drivers who simply miscalculated would not be penalized, but those who ran the light deliberately would be. Yes, some drivers would deliberately run the light to try to beat the 0.5 seconds, and yes, some might miscalculate by 0.5 seconds or more, but on the whole, you’d punish those who need to be punished and not those who made an innocent mistake.

  2. trumwill says:

    It’s not just a matter of fairness. My understanding is that most major light-running accidents occur with people that either deliberately run the light or are not paying attention to the light. Enough people know to look both ways before entering an intersection.

  3. Mike Hunt says:

    By introducing a profit-making organization into the mixture, you are asking for a world of trouble. While some would argue that the police are one already, they are only one indirectly. With a private company there is no grey area regarding the matter.

    OTOH, ond could argue that the reason cities don’t already have light timers is that they want the increased revenue that red light runners generate. After all, barring information overload, more is better than less, and since pedestrians already have them, then drivers should too.

  4. trumwill says:


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