January 18, 2005
More red light debates

Supporters and detractors of traffic light cameras duke it out with competing studies which may or may not show that such cameras reduce collisions at intersections. I'll simply note again that Fritz Schranck has discussed this issue in the past, and leave it to you to figure out which side's scientists can beat up the other's.

One item of interest from the article:


In discussing alternatives to red-light cameras, [Eric Skrum, spokesman for the National Motorists Association of Waunakee, Wis., a nonprofit group that opposes camera enforcement] said that lengthening the time of yellow lights can reduce violations and that the [Transportation Research Board] underplayed that possibility. He contends that most drivers run red lights because yellow lights are too short and don't allow time to stop safely.

For example, Skrum said a 2002 San Diego study that reported a reduction in red-light running buried the fact that the greatest reduction in red-light violations, 88 percent, was at an intersection where the yellow light duration was increased from 3.1 to 4.7 seconds. At five other San Diego intersections, the number of violations also significantly dropped due to longer yellow lights.

Additionally, Skrum said, increasing the yellow-light duration from 4 seconds to 5.5 seconds in an intersection in Fairfax County, Va. already equipped with red-light cameras reduced red-light violations by 96 percent.

He said communities that install red-light cameras rather than lengthening yellow lights or making other engineering changes are more interested in increasing their cash flow than reducing accidents.


I'm very skeptical that lengthening yellow light durations could have such a dramatic effect on red light running. Ninety-six percent reduction? Show me the data. Frankly, I'm not convinced that longer yellows wouldn't lead to an increase in red light running, since people approaching a light that has just turned yellow will think "no problem, the yellow lasts forever" and speed up.

Getting back to the cameras themselves, you may recall the story about Dallas' Deep Ellum installing surveillance cameras. According to the CrimProf Blog, such cameras are a lot more widespread than you might think. Does that make you a little uncomfortable? I know I am.

Posted by Charles Kuffner on January 18, 2005 to Planes, Trains, and Automobiles | TrackBack
Comments

There's no question that yellow lights should be consistently timed & long enough so that someone approaching at the speed limit can make it from the "point of no return" (closer to the intersection than normal stopping distance) to the other side of the intersection before the light goes red.

But there's some driver retraining that needs to happen too. I've heard people complain, completely seriously, that the problem with red light cameras is that you might enter an intersection in the final seconds of the yellow light and thus get ticketed when it turns red.

Which is, in fact, the law as I learned it: yellow means stop if you can do so. Without some reminders of this (and I think automated tickets that cost some money, but don't put points on your license are a good tool here) longer yellows are in effect just cycle-lengtheners as people continue through the light for a few seconds after it turns red.

I'm far less troubled by red light cameras than by other surveillance cameras. When you're driving, you're doing something that we have as a society agreed should be regulated by the government - we set standards for drivers, people have to demonstrate that they meet these standards, and obey a code of rules about how they do it. It's reasonable to have some monitoring in that case. It's a much more problematic area when you're monitoring people because they happen to be on the sidewalk, and that starts to erode our ideas about public space.

Posted by: John on January 18, 2005 11:28 AM

I don't think they need to lengthen the yellow. I think they need to lengthen quite a few *greens*, particularly in left turn lanes. There are a lot of left turn lanes in this town where a third car waiting at the red has to go through a stale yellow, and that's just ridiculous.

Posted by: Tim on January 18, 2005 6:30 PM

Dear Charles:
Went to a TRB session on red lights last week, and may blog about it tonight, thanks to this post.
Two quick points:
Yellow time is supposed to represent the time needed to cross the intersection if the light turns to yellow just as you cross the stop bar. RLC jurisdictions are recommended to add a few (.3 or so) seconds to that interval, JIC.
I saw a presentation on a cost benefit analysis of injury costs comparing right angle accidents to rear end at RLC intersections that shows reduced total accident costs at such locations--but not as much as I expected.
/f

Posted by: Fritz Schranck on January 20, 2005 5:28 AM

One concern I haven't heard mentioned is the use of these cameras to "catch" people who happen to be driving in the wee hours of the morning, stop at one of these intersections, and, seeing no visible traffic in any direction, decide not to wait for the light to change.

Sure, it's a violation. But it seems quite, well, picky to enforce the red-light law in these cases.

I'm not convinced that longer yellows wouldn't lead to an increase in red light running, since people approaching a light that has just turned yellow will think "no problem, the yellow lasts forever" and speed up.

You're absolutely right; a yellow that lasts too long can be as bad as one that's too short. And that "96% reduction" trips my bogometer, too.

The allegation in San Diego, though, was that the yellow lights had been deliberately set too short, because both the city and the company monitoring the red light photos were allegedly more interested in generating revenue than in reducing red-light running.

If Houston goes through with this, they need to take precautions to avoid that temptation.

I've heard people complain, completely seriously, that the problem with red light cameras is that you might enter an intersection in the final seconds of the yellow light and thus get ticketed when it turns red.

Which is, in fact, the law as I learned it: yellow means stop if you can do so.

That's the law I learned too. Unfortunately, that was in Oklahoma. My understanding of Texas law, though, is that it's only illegal if you enter the intersection when your light is red. You may think that's ridiculous, but unless I've been misinformed, that's Texas law.

My city - Garland, a Dallas suburb - has a few red-light enforcement cameras, but they follow the "Texas" standard: you're only ticketed if you enter the intersection when your light is already red.

As I understand it, though, the Houston proposal is to broaden the law to the more common "Oklahoma" standard.

I don't have a problem with that, as long as the city (1) provides "fair warning" of the tighter standard; and (2) lengthens the yellow-light times slightly to account for it.

When you're driving, you're doing something that we have as a society agreed should be regulated by the government.... It's reasonable to have some monitoring in that case. It's a much more problematic area when you're monitoring people because they happen to be on the sidewalk, and that starts to erode our ideas about public space.

I generally agree. Red-light cameras are triggered when someone enters the intersection when their light is red (or, in Houston's proposal, stale yellow).

But then they just take several snapshots of the intersection. They will inevitably capture activity other than the light-running vehicle.

That may not concern you. Certainly, a red-light camera isn't nearly as intrusive as an always-on surveillance camera. Red-light cameras have been in scattered use for over a decade, and I haven't heard of any abuses, other than yellow-light mistiming cases as in San Diego. (In contrast, there have been worrisome cases involving surveillance cameras; e.g., the woman caught beating her child by a Wal-Mart parking lot camera.) Perhaps that will change as red-light cameras become more common, but I'm not terribly discomfited by the possibility.

But I won't pooh-pooh the concerns of those who are just yet.

Posted by: Mathwiz on January 21, 2005 2:38 PM

When the light turns amber slow down. When the light turns red stop. People out driving around in their cars have no reasonable expectation of privacy because they are driving around in public. Cameras cannot see inside the car or inside the trunk or inside ones pockets. If one insist on speeding up when the light turns amber then one needs to go back to drivers school. And another thing. People who run red lights will eventually have an accident and it will either hurt or kill someone. For what?

Posted by: tommy on October 9, 2005 1:48 PM

if you come through sigal light and you are in the middle of it and light turns yellow and camera flashes; are you considered a red light runner?last week i went through as soon as i past white line at intersection two seconds later camera flashed;if i pass white line at intersection on green can i get ticket?

Posted by: eric fultz on January 1, 2006 1:10 AM

November 15, 2001: "At that signal [meaning US50 and Fair Ridge Dr.], VDOT raised the amber time from 4.00 seconds to 5.50 seconds due to the large number of accidents at that intersection. As a result of the increase in amber time, the violations dropped by approximately 90%." [Young Ho Chang, P.E., Director, Department of Transportation, Memo to Fairfax County Board of Supervisors dated 11/15/01, File 5-19, Subject: Photo Red Light Program]

By the way, the yellow lights at the RT7 and Towlston Rd. cam site in Fairfax County were secretly increased not just once but twice. "Red light running" dropped about 93 percent ..... and the red light cam at this notoriously dangerous intersection later went out of business.

So why do you suppose the yellow lights at these dangerous intersections weren't increased as a first course of action (e.g. before resorting to inherently dangerous red light cameras)? Hint: Money. Money. Money.

Food for Thought: What do you think of officials who deliberately withhold prescribed engineering safety countermeasures that work so other people can operate red light cameras under ongoing dangerous conditions instead?

People like Charles Kuffner can remain in denial and otherwise choose to be ostriches if they wish. But they ought not be able to do it at the expense of an unsuspecting public. The stakes are way too high.

Gene Quinn
Vienna, VA

PS Mr. Chang left the employ of Fairfax County in early July 2005, about a week after all the inherently dangerous red light cameras in Virginia were turned off.

Posted by: Gene Quinn on May 16, 2006 5:52 AM

I recently went through the Houston intersection at Bay Area Blvd and El Camino Real. The light was changing to yellow as I entered the intersection and was still yellow as I exited the intersection yet very bright lights were flashing all around me (there were other cars going through as I was). Is Houston ticketing now for yellow light runners at this intersection? And, if not, why are the cameras set to go off at yellow causing a major distraction to drivers and creating a safety hazardous that wouldn't have existed if bright lights weren't flashing at drivers.

Posted by: confused on November 10, 2006 9:30 AM

I would like to respond to Mr. Quinn's May 16, 2006 posting. It is interesting how people can add one and one get three.

Money was never the object of installing red light cameras in Fairfax County. We believed that the installation of red light cameras would reduce the number of intersection crashes (especially the angle crashes that are more dangerous). As a matter of fact, the County never "made money" on the program. One of the chief reasons for installing red light cameras in the County was given by the Police Department which lacked the resources to catch red light runners since to do it safely requires two policemen stationed such a way to catch the lights changing from one side of intersection and to run down the violator from the other side of the intersection.

As far as the amber timing is concerned, the state maintains and operates all the signals in Fairfax County, therefore, the county has no control over the timing of these signals. The County identified the most dangerous intersections and then requested the state to review them for any timing or engineering changes before installing the red light cameras.

It is correct that the amber time were changed on a number of intersections after the installation of the cameras and there appears to be a correlation to the significant drop in the red light running violations. And as you quoted from my report to the Board of Supervisors, we reported in as factual manner as possible - there was no attempt to hide anything from the public.

By the way, the Virginia General Assembly did not extend legislation that allowed the use of red light cameras by certain jurisdictions in the state. That was the reason the cameras were turned off in Fairax County.

I still believe that the red light cameras can be an effective tool to improve intersection safety if used in judicious and deliberate manner. That is, review the intersection for any engineering and signal timing improvement first before installation of red light cameras.


Posted by: Young Ho Chang on December 6, 2006 8:25 AM