Bus monitoring and control experiment and the assessment of its effects on bus operation

London Transport has installed a continuous vehicle monitoring system on Route 11 buses. It uses the odometer principle to locate the buses and operates with a two channel radio system under the control of a central computer. An interrogation every five seconds causes each bus to transmit data which is interpreted by the computer. The format of the data transmission is described and the ways in which corruption of the message were occurring in the system.