UT professors analyze dilemmas in red light camera programs - WRCBtv.com | Chattanooga News, Weather & Sports

UT professors analyze dilemmas in red light camera programs

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Professors at the University of Tennessee analyzed traffic cameras to determine if control measures determined to boost revenue compromise safety.

The study was published on the university's website and stems from the practice of some municipalities engineering their red light cameras in order to boost revenue from violations.

Methods include shortening yellow light time or increasing the speed limit on a street. Most municipalities get their red light camera systems through private vendors and pay for them either through a monthly flat rate or a portion of citations. The more successful the red light cameras are at increasing safety, the less profitable they become.

"Traffic engineers are facing an ethical dilemma of balancing revenue generation to sustain their red light camera programs with their traffic safety and efficiency goals," said Professor Lee Han. "This is a new conundrum for them."

Three Civil and Environmental Engineering professors analyzed the red light systems on four measures: shortening yellow duration and/or lengthening all-red duration, shortening cycle length, increasing the speed limit and increasing high volume-to-capacity conditions such as with an unwarranted turn signal. They also measured impact on red light running, safety, and efficiency.

They found shortening the yellow and/or lengthening the all-red, shortening the cycle length, and increasing the speed limit increased the chance of drivers running a red light. Shortening the yellow and increasing the speed limit increased the chance of a crash. Shortening the yellow and/or lengthening the all-red and increasing the speed limit did not impact efficiency of traffic flow. Increasing high volume-to-capacity conditions increased the chances of traffic congestion at a signal but not the chances of running a red light or crashing.

According to the researchers, within the bounds of engineering design standards, there is room for traffic engineers to apply their judgment and develop the best signal-timing strategy. They note that while each strategy has its merits and faults, a combination of the strategies could possibly produce adequate revenue without causing traffic delays or congestion.

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