After analyzing this information, traffic engineers can determine what the problems are and propose solutions for each. To help local officials decide which options to pursue, engineers can also forecast what kinds of crash and injury reductions can result from improvements and how long it would take for funds spent on them to be offset by lower costs from fewer crashes. Solutions, of course, will vary with each intersection. Usually, a camera is mounted on a pole and wired to a traffic signal, with sensors buried in the intersection. If a vehicle crosses the sensors while the light is red, that triggers the camera, which produces a photo showing the car, its license plate, and the date and time of the violation.
Police mail a ticket with the photo to the vehicle's owner.
These cameras, in use in at least several dozen cities, do reduce red-light violations, several studies have shown. The IIHS says such violations dropped 42 percent in Oxnard, Calif., and 44 percent in Fairfax, Va., after red-light cameras were introduced. Based on preliminary results of programs in three areas, the Federal Highway Administration said photo radar should reduce red-light violations by 20 percent to 60 percent. A poll conducted for the Advocates for Highway and Auto Safety in 1998 showed that 65 percent of the public supports use of red-light cameras. However, only 10 states and the District of Columbia have laws specifically allowing such cameras.