Monitoring the San Francisco Bay Area Freeway Network Using Probe Vehicles andRandom Access Radio Channel

摘要

The lack of proficient real-time traffic monitoring systems is one of the majorbottlenecks of Advanced Traveller Information Systems (ATIS) and Traffic Management Systems (ATMS). In this report we describe a method of collecting real-time traffic data from probe vehicles automatically sending traffic reports to one or more base stations, connected to a traffic center by a wired communications network. Analyzing and computing road traffic and message traffic flows in the San Francisco Bay Area, we study several multi-disciplinary aspects of this data collection technique, such as the relation between vehicle traffic and message traffic, the influence of road traffic congestion on communication performance, the reliability of road traffic estimates on radio network throughput and the location of base stations. The results presented in this report reveal that random access (ALOHA) transmission of traffic messages is a (spectrum) efficient, inexpensive and flexible method for collecting road traffic data and that this approach can provide reliable traffic monitoring. Not only highly accurate real time link travel times can be estimated, but also Automatic Incident Detection (AID) can performed.