M25 controlled motorway - results of the first two years

A pilot of a \´controlled motorway\´ has operated on the southwest quadrant of the M25, the London orbital motorway since August 1995. The concept behind the pilot was that by controlling the speed of traffic at times of heavy flow, flow breakdown might be delayed or prevented, resulting in a reduction in accidents, an increase in "driver comfort" and possibly an increase in throughput over the controlled section. This paper describes the monitoring and assessment of the scheme, undertaken by the Highways Agency and its contractors, and summarises the results obtained over the first two years of operation.