An Analysis of Red Light Running

I see a lot of responses to photo enforcement where people oppose the speed cameras but support red light cameras. After all, red light running does seem inherently more dangerous and anything that can stop it must be good, right? But most people haven’t thought this through all the way. Let’s take a closer look.

There are only a few different scenarios for red light runners:
1. Trying to beat the light – They approach the intersection as it turns yellow, and they decide to go for it rather than stopping. Frequency: High
2. Unintentional – didn’t see or recognize the light or thought it was green. Frequency: Low
3. Blatant disregard for the signal. Frequency: Low
4. Right turn on red without stopping. Frequency: High

Scenario 1 is probably the most common. These are your average drivers who just make an error in judgment as they approach the intersection. If a red light violation occurs, it is most often the during the first 1 second or so of the red light, during the all clear interval. Cross traffic hasn’t yet started, and most cross-traffic will look at the on-coming traffic to make sure the cross traffic is going to stop. Overall, this event is fairly non-dangerous. If anything, there is considerable danger by drivers who slam on their brakes and surprise the drivers behind them, leading to a rear-end collision. Danger: Low

Scenario 2 is VERY dangerous. The driver unknowingly proceeds into the intersection at a dangerous time when no one is expecting it. Danger: High

Scenario 3 is fairly rare. Even the most callous drivers do not casually plow through a crowded intersection. They will look carefully before running a light, especially because they will be on the lookout for cops and cameras, plus they don’t want an accident either. Danger: Low

Scenario 4: Turning right on red is usually done with a careful glance and at least a pause before proceeding. Speeds are low and it is easy to stop if there is a problem. Danger: Very Low.

Now let’s examine the effectiveness of cameras in each of these scenarios:

Scenario 1: Drivers trying to beat the light may or may not notice the presence of the cameras. Effectiveness: Medium.

Scenario 2: Drivers are oblivious to the light, they will not be aware of cameras. Effectiveness: Low

Scenario 3: Drivers who intentionally run lights are probably very aware of the situation. They will be looking for cops and cameras. Effectiveness: High

Scenario 4: Red light turners may or may not be aware of the cameras, and they may or may not be aware that the cameras may catch right turners. Effectiveness: Medium.

An Analysis of the effectiveness of Red Light Cameras

An Analysis of the effectiveness of Red Light Cameras

Conclusion: Theoretically, when it comes down to it, the cameras are most effective at the least dangerous red light running behaviors! And conversely, the cameras are least effective at deterring the most dangerous behaviors.

This is most likely the reason why cameras are very ineffective at reducing accidents… and often see accidents increase.

This brings me to what is the most effective argument against red light cameras. Cities are resorting to the cash cow of enforcement in lieu of engineering. Engineering improvements yield permanent, lasting results and achieve compliance naturally. Most engineering improvements don’t require a lot of money. Such examples are adjusting light timing, pavement markings, signal visibility, and signs. Signal timing adjustment is proven to be highly effective – reducing violations by as much as 80%.

Officials must think that the reason why some intersections are more dangerous than others is because scofflaws are attracted to some locations more than others. The reality is, the same drivers are driving through the every intersection. If one intersection is more dangerous than another, it’s because of the intersection, NOT the drivers!

If safety really were the interest of government, why wouldn’t they invest a little bit of money on permanent, lasting results and natural compliance? Why wouldn’t they fix their defective intersections and let their citizens go about their lives unburdened? I think the answer is clear… it’s all about the money.



  1. Posted May 17, 2009 at 1:37 am | Permalink

    Good post. A very well thought out analysis.

  2. Ben Buette
    Posted May 20, 2009 at 3:01 pm | Permalink

    Something should be done about the intersection Oracle & River in Tucson. I don’t understand why some oficial doesn’t take a stand and do something. The court could, but won’t. There is no Photo Enforcement sign there. Wouldn’t that fact give cause for dismissal of a photo ticket?

  3. Sandy
    Posted July 6, 2009 at 10:32 pm | Permalink

    Thank you for helping me understand how this works. I just got a ticket for failure to stop at a red light when I was making a right turn in a right turn lane. I had no idea it is a law that you must come to a complete stop before turning. There is no crosswalk at this intersection. I am a very careful driver and resented this ticket. This $50 was a burden to pay during lean economic times. I was on my way to my mother’s and stopped at Wal Mart for a few items. I won’t stop here again, so the city will lose my business and money in the longrun. I believe this is just an easy way to generate city funds for something everyone does every day.

2 Trackbacks/Pingbacks

  1. […] cameras. On the surface, this makes sense. After all, the danger of running a red light (read my analysis of red light running here) can be envisioned a lot easier compared to simply driving 1 mph above an arbitrary limit. Compared […]

  2. […] Analysis of Red Light Running, Part 2 As an update to an earlier post (An Analysis of Red Light Running), some new information has come to my attention to bolster the arguments made in that […]

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