This paper presents the data collection, data processing and travel information presentation facilities of the traffic control system of the Metropolitan Expressway Public Corporation (MEPC) in the Tokyo area of Japan. In January 1994, the Metropolitan Expressway network had 18 routes of total length 231 km and an average traffic volume of more than 1.1 million vehicles per day. Data are collected mainly by using: (1) ultrasonic vehicle detectors at 300m intervals; (2) closed circuit television (CCTV), usually every 1km but every 100m to 150m in tunnels; (3) emergency telephones, usually every 500m but every 100m in tunnels; and (4) patrol cars. Local information is transmitted to the central computer every 5 min. Vehicle detector data are aggregated every minute, and used to calculate average traffic speeds. The processed data are displayed on various information boards, and updated every minute. The information boards are: (1) 408 character displays on motorways; (2) 25 graphic displays on motorways; (3) 190 character displays on streets; (4) 37 graphic displays on streets; and (5) 5 travel time displays, which are described in some detail. There are also 11 highway advisory information radio stations, and information terminals at 10 sites.
Samenvatting