MONITOR - An automatic bus location and communications system for Chicago

Since 1970 the Chicago Transit Authority has had location-equipped vehicles in revenue service. Subsequently, the entire fleet, of over 2400 vehicles has been equipped with two-way voice/data radios with the location feature. Since the initial 1970 Demonstration, the location technique of "broad-field proximity" (high-band VHF signposts) has been utilized, to provide location information. This paper will describe the system configuration and operation, including design criteria such as RF coverage areas, channel assignments and loading, and computer polling rates for location and automatic correlation data (bus number versus Garage/Run number). Emphasis will be placed upon the dual computer system (host front-end) which includes: system monitoring by central dispatchers; emergency alarm (with location) monitoring and reporting; mobile mechanical irregularity monitoring and reporting (equipment fault isolation - through mobile unit diagnostics); MIS capability; and future AVM function monitoring and reporting (start run indicators on board the vehicles, passenger counter, and odometer data acquisition). System reliability and availability levels experienced, as well as maintenance procedures utilized will be outlined. System expansion capabilities, and flexibility will be described, including the incorporation of routine bus transfers between garages, and the addition/deletion of vehicles in the system.