In this series of case studies by Jay Beeber, Executive Director of Safer Streets L.A., data from various jurisdictions where the yellow interval was increased confirm that a significant safety benefit can be achieved.
Increasing the duration of the yellow signal at eight intersections in Chandler, Arizona reduced accidents, according to six years’ worth of data collected by the city.
A 30-second video produced by the oos
This video presentation of some of Chicago’s top-grossing red-light cameras clearly documents how the yellow lights are timed at less than 3.0 seconds. Not only is this a violation of federal regulations, it degrades intersection safety and puts motorists at an increased risk for accidents.
After Albuquerque, New Mexico ceased its red-light camera program, city officials decided to apply a modest increase to the yellow signal duration at eighteen of the twenty intersections where cameras had previously been used. A report found the change had produced a measurable benefit.
Commissioners in Collier County, Florida voted to pull the plug on red-light cameras. The devices had stirred controversy and class action lawsuits since ticketing began at ten county intersections. City officials were unanimous in demanding an increase in the duration of the yellow lights at intersections.
Red Light Citations Drop Below One Per Day
When officials in Fairfax County, Virginia increased the yellow-light time at an intersection with a red-light camera that wasn’t reducing accidents, incidents of red-light running dropped 96 percent.
Effect of Yellow-Interval Timing on Red-Light-Violation Frequency at Urban Intersections
This study shows that an increase of 0.5 to 1.5 seconds in yellow-light duration will decrease the frequency of red-light running by at least 50 percent.
Thanks to a simple traffic engineering fix — increasing the yellow light duration — the number of left-turn violations in Loma Linda, California dropped 80 to 85 percent from about 240 monthly violations to about 25 or 30 a month immediately after the change. Straight through violations were reduced 92 percent.
Engineering solutions and an extra second of yellow duration made red light cameras a money loser in San Carlos, California.
Proponents of red light cameras claim that increasing the yellow light time is not a solution because motorists will adjust to the lengthened yellow light time. These studies prove the proponents are wrong.
Yellow Light Duration Impact On Driver Response
This report from the Institute of Traffic Engineers Journal examines how drivers react to differing yellow light durations.
6 Cities That Were Caught Shortening Yellow Lights For Profit
An article on the oos blog that highlights six cities that were caught shortening yellow light times to increase ticket camera profits.
A project, sponsored by the Oostwestthuisbest Base, that aims to establish yellow light standards and prevent the shortening of yellow light times.
SaferStreets LA offers some more evidence of the impact that longer yellow lights have on red light violations.