An unconventional approach to automatic vehicle location and control for urban transit

A low-cost system that makes use of simple passive tags on buses is being developed. These tags are detected at strategically-placed locations throughout the service area. Tests of two technologies (surface acoustic wave and modulated backscatter) which could accommodate this system concept are described. The user requirements in the areas of service control, public information, and planning and management information are discussed. For service control, an exception-based reporting approach will be taken. The locations of on-street detectors will be based on the control strategies available at individual sites. A system designed to provide passengers at busy bus stops with information about the order of approaching buses is described. Real-time bus location information will also be used to update automatically a computerized telephone information system. Service monitoring for planning and management information will be enhanced by the addition of detectors at points other than those selected for service control, and the passage of vehicles will be recorded at all times.<
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