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Red Light Cameras


Yellow Light Timing Myths

Proponents of red light cameras will often criticize the lengthening of the yellow light time as a solution to red light violations. They claim this is a short-term solution because motorists will become acclimated to the longer yellow light time and continue to violate the light.

Not true. Adjusting the yellow light time to an appropriate length for an intersection reduces the amount of red light violations. And, studies have shown that the motorist does not become acclimated to the new timing and violations do not resume. Here is a list of those studies illustrating the invalidity of their claims:

"The data show that the percentage of last-to-cross vehicles clearing the intersection (T+0.2) seconds or more past the yellow onset was not appreciably changed by the extension of the yellow phase."
The Influence of the Time Duration Of Yellow Traffic Signals On Driver Response, Stimpson/ Zador/ Tarnoff, ITE Journal, November 1980

"Research has consistently shown that drivers do not, in fact, adapt to the length of the yellow."
Determining Vehicle Change Intervals - A Proposed Recommended Practice", ITE, 1985

"Olson and Rothery reported in 1972 that their research showed that drivers were "virtually" certain to stop if their required deceleration rate was less than 8 feet per second squared and virtually certain to continue if the deceleration rate required was in excess of 12 feet per second squared"
Determining Vehicle Change Intervals - A Proposed Recommended Practice", ITE, 1985

"The average implied deceleration rate of the group with the highest crash rate was slightly over 13 feet per second squared, and the deceleration rate for the group with the lowest crash rate was 8.5 feet per second squared"
"Effect of Clearance Interval Timing on Traffic Flow and Crashes at Signalized Intersections", Zador/ Stein/ Shapiro/ Tarnoff, ITE Journal, November 1985

A real world example that illustrates that motorists do not adjust to the yellow light time and begin violating red lights again can be found in Fairfax County, Virginia. The engineers increased the yellow light time on March 26, 2001 from 4 seconds to 5.5 seconds with a result of a 96 percent decrease in violations. For the full story on this, visit this page.

Go Back To Yellow Light Timing Page

 

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NMA Position on Red Light Cameras

The NMA opposes the use of red light cameras and proposes engineering solutions as the real fix for intersections with high accident rates.


NMA Red Light Camera Fact Sheet

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