Speed-control and incident-detection on the M25 Controlled Motorway (Summary of results 1995-2002)

A Controlled Motorways scheme was introduced on to the M25 in August 1995. The scheme now extends from Junction 10 to Junction 16. This report presents an overview of the monitoring work undertaken by TRL for the Highways Agency between 1995 and 2002. As well as describing the history of Controlled Motorways, the report presents key results for performance indicators, a variety of traffic trends and behaviour, and a number of specific studies carried out alongside regular monitoring work. The report describes the trends in traffic behaviour and the performance of the Controlled section of the M25 since the implementation of Controlled Motorways. It also presents the results of a driver opinion survey, which provided a detailed understanding of how the Controlled Motorway was perceived by its users. The results of investigations into the effects of the variable speed limits on accidents, noise and air pollution are presented. (A)