Monday, April 14, 2008

Cities across the U.S. have been caught manipulating their traffic lights

Go to ARS Technica original
Red-light cameras are often billed as a great way to improve traffic safety and prevent speeding. A few cities across America, however, have been caught short-timing their own yellow lights below legal levels, in what may be an attempt to boost ticket revenues by giving drivers less time to come to a stop. So how many anecdotes do you need to pronounce something a trend? It's hard to say, especially when the anecdotes in question support the abolishment of something as universally hated as the red light camera.

Six possible red light "gotcha" stories, some of which go back as far as 2005, were originally reported by theNewspaper, but were compiled into a single list of events by One city, Chatanooga, TN, has been forced to repay the $8,800 it collected in ticket revenue, while investigations in Dallas, Texas and Springfield, Missouri, have uncovered evidence of similar practices, although no charges have been filed.

In the single court case that has occurred thus far, Chattanooga's city traffic engineer John Van Winkle testified that the yellow signal light should be (and was) turned on for the 3.9 seconds necessary to meet basic safety standards. The judge in question ordered the claim verified, and discovered that the light was only set for 3s—significantly less than the 3.9 second minimum. Van Winkle claims that the problem was caused by an accidental mixup with turn arrow timing, but there might be more behind the issue. According to confidental documents released in 2001, Lasercraft, the company behind Chatanooga's red camera lights, only installs red light cameras at high-volume intersections with an "amber phase" of less than 4s.

None of the other cities are facing court actions, but investigative reports have turned up troublesome trends. In Dallas, yellow lights at the city's revenue generators camera-enforced intersections were timed for just 3.15 seconds, or 0.35 seconds less than the Texas Department of Transportation minimum. In this case, a third of a second may make a substantial difference in revenue—theNewspaper reports that most (80 percent) red light tickets are issued less than one second after the light has turned to red. Ironically, Dallas is now considering scrapping its ticket revenue program, after new legislation forced the city to post signs alerting drivers to the existence of the cameras as well as requiring all towns to send 50 percent of their camera-derived income to the state's coffers.


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