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Directions in Highway Safety, Spring 2007 Cover Page Download Newsletter pdf
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Spring 2007 | Vol. 10 | No. 1

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Red Light Cameras Affect Positive Change in Philadelphia

The Insurance Institute for Highway Safety (IIHS) recently published a report concluding that the introduction of red light cameras at two high crash rate intersections in Philadelphia nearly eliminated red light running violations. The number of violations at control group intersections remained about the same.

The two principal methods used to reduce red light running are lengthening the duration of the yellow signal phase and implementing automated red light enforcement. The IIHS study measured the incremental effectiveness of both. At the experimental and control intersections, researches recorded the number of red light violations at three points in time: first, before any changes were implemented; a second time, several weeks after the yellow change intervals were increased by about one second; and finally, about a year after the subsequent introduction of red light camera enforcement.

Red Light Camera

The study found that increasing the yellow signal time was effective, reducing violations by 36 percent. However, the addition of red light cameras (several months after the yellow light interval increase) showed an additional 96 percent reduction in the number of red light violations. This data demonstrates that adequate yellow signal timing does reduce red light running, but longer yellow timing alone does not suffice: communities also need the strengthened enforcement that red light cameras can provide.

The Philadelphia study reinforces prior research that also saw a considerable decrease in red light running after the introduction of red light cameras following lengthened yellow signals. However, this study reports larger reductions than prior assessments. Researchers note this could be due in part to the small number of affected intersections, coupled with aggressive public awareness, conspicuous warning signs, heightened news coverage and steeper fines ($100, compared to $75 in nearby Delaware and Maryland, or $50 in New York).

The Pennsylvania legislature authorized the use of red light cameras at several specific intersections in Philadelphia in 2004. The law is scheduled to sunset in 2008. It permits photographing the rear license plates of vehicles entering intersections on a red signal. Drivers are not captured on film. It also required a 120-day warning period, during which law enforcement mailed warning notices, instead of tickets, to the registered owners of the affected vehicles.

Philadelphia hopes to expand its current program, and advocates are working to eliminate the planned sunset.

For a copy of the full report, contact IIHS: