Using GPS as part of an on-bus video system for bus lane enforcement

The article describes the trial of GPS (Global Positioning System) and video equipment demonstrated to the Traffic Director for London by TecnEcon and the lan Catling Consultancy (ICC) in February and March 1996. The objective of the trial was to assess the potential for using GPS equipment fitted on buses for two purposes: to provide location data which could be used to switch enforcement video cameras on and off according to the presence of the bus at a bus lane; and to provide location data on video images should they be used in any prosecution process. TecnEcon and ICC arranged for the loan by BT Research Laboratories of suitable GPS equipment for the trial. A Navstar GPS receiver was used, with the capability of accepting differential GPS. This capability was analysed using a post processing technique in which differential data was recorded at a base station at BT in Ipswich, and the data recorded on the bus was subsequently corrected using the differential data. In addition to the GPS equipment, TecnEcon provided video and computing equipment which were linked to the GPS receiver, and BT loaned an HP portable computer with software set up to record the GPS data for subsequent differential correction. The equipment was configured in order to carry out three linked demonstrations: the real time position of the bus displayed as geographic coordinate information on a video image taken by a camera at the front of the bus; the real time location of the bus on a laptop computer display showing the road network; the recording of the GPS data for subsequent differential correction.