AUTOWARN - A MOTORWAY INCIDENT DETECTION AND SIGNALLING SYSTEM. SECOND INTERNATIONAL CONFERENCE ON ROAD TRAFFIC MONITORING

This paper described the autowarn system, installed on the m4 motorway between the m4/m5 almondsbury interchange and the severn bridge toll booths. This system automatically detected traffic incidents and switched on the motorway warning signals to warn approaching drivers of obstructions ahead. Details of system design and operation were provided, as was the method used to evaluate the system. Evaluation on catherine hill was split into 3 phases: (a) a study of the system when running on freely flowing traffic with no incidents on any part of the road; (b) a study of incidents, to obtain optimum performance and to assess whether the system was viable; and (c) evaluation by police. In this phase police compared settings made by the system with those they would have made themselves. The system was found to be both viable and useful. The police agreed with 95% of the settings either made or recommended by the system, and found that it provided a more accurate warning to drivers, as well as saving police time. (TRRL)