Traffic Light Camera Study Reveals
Red Light Violations Reduced

Which situation causes drivers to stop most accurately at a red light -- an extended yellow light that provides increased warning time, or a camera that snaps photos of red-runner license plates?

You probably guessed it. While both measures reduces traffic signal violations, it's the cameras that make the far bigger difference. In fact, they all but eliminated signal violations at a busy Philadelphia intersection during a recent study by the Insurance Institute of Highway Safety (IIHS).

"Violations virtually disappeared at the six approaches to the two intersections we studied. This decrease in violations is all the more remarkable because the intersections were such high crash locations. In fact, they had been identified as having some of the highest crash rates in the nation," says Richard Retting, the Institute's senior transportation engineer and lead author of the Institute's new red light camera study.

Researchers tallied signal violation rates at intersections before and after extension of yellow lights and again after red light camera enforcement had been in effect for about a year. The first step reduced signal violations by 36 percent. The cameras reduced the remaining violations by 96 percent. At the same time, violations didn't change much at intersections without cameras in Atlantic County, New Jersey, about 50 miles away.

How they work and why they're needed
High red light violation rates have been recorded at busy urban intersections, and the rates increase during peak travel. The result is crashes, including serious ones. Red light running causes about 800 crash deaths per year, and about half of the people who are killed aren't the signal violators. They're pedestrians and people in vehicles that are struck by motorists committing the violations. Another 165,000 people are estimated to be injured in red light running crashes each year.

Cameras help by deterring violators and, thus, preventing collisions. The cameras, connected to signal lights and sensors that monitor traffic, automatically photograph vehicles driven into an intersection after the light has turned red -- not just as the light changes but a specified amount of time after.

The 2004 legislation authorizing camera use in Philadelphia requires photos of the rear license plates of vehicles in violation but not images of the motorists. Owners of the identified vehicles are subject to $100 fines.

"This policy flies in the face of red light camera critics who claim the cameras are all about catching people, writing lots of tickets, and raising money," Retting points out. "The true purpose of cameras is to reduce crashes by getting motorists to stop at red lights, so the most successful programs don't produce any revenue at all."

Results of the Philadelphia study also rebut camera opponents who insist that lengthening yellow signal intervals is all that's needed to reduce intersection crashes. It isn't. Appropriate yellow intervals are important, but cameras make a much bigger difference.

(Source: IIHS)