England
Variable Speed Limits Reduce Accidents Significantly in the U.K.
Summary Information
Speed limits were adjusted in response to the level of congestion on the M25, one of the most congested freeways in England. Using dynamic message signs (DMS) and loop detectors measuring traffic density and speed, speed limits were lowered in increments as congestion increased. Speed cameras were used to enforce the speed limits, resulting in 26,000 fines.
The study found that motorists were more inclined to keep to their lane when a "faster lane" no longer existed. They were also more inclined to keep to the inside lane and to keep proper distances between successive vehicles, resulting in smoother traffic flow which actually increased average travel times of traffic. Results show that traffic accidents decreased by 28 percent during the 18 months of operation.
