The Hanshin Expressway Public Corporation began the operation of the traffic control system in 1970. The system has collected traffic data such as traffic volume, time occupancy and time mean velocity from ultrasonic vehicle detectors equipped on the network every 500 meters automatically. Recently, in operation of the system, there are some problems caused by a limitation of an Eulerian way of measuring traffic data. On the other hand, collecting positioning data with handheld Global Positioning System (GPS) and mobile communication devices is becoming popular in Japan. This paper aims to show the possibility of using mobile positioning systems for estimating traffic information. Accuracy of travel-time and time mean velocity on the Hanshin Expressway estimated from positioning data is verified by comparison with ones measured by AVI (Automatic Vehicle Identifiers) and vehicle detectors. The time interval of data collection and the percentage of probes necessary to obtain accurate and credible traffic information are also discussed.
Abstract