Patent GB-1231794-A (GB)
IPC: G01S13/931
Filed: 1967-05-03
Abstract: 1,231,794. Pulse radar. E.M.I. Ltd. 3 May, 1968 [3 May, 1967], No. 20662/67. Heading H4D. [Also in Division G4] In a road vehicle control system, in which each vehicle has ranging apparatus, such as radar, providing an indication of the position of the next vehicle ahead, to enable a merging vehicle to enter a traffic stream P1, P3 the merging vehicle is arranged to run beside the traffic stream for at least a predetermined distance so that the ranging apparatus on the vehicles in the stream can detect the merging vehicle and vehicles following the position in the stream which will be occupied by the merging vehicle can fall back from that position prior to entry of the merging vehicle. Each vehicle may have a forward facing interrogator and a rearward facing transponder. The control system may be used for buses where the radar apparatus in each bus gives an indication to the driver in the form of a deviation from a predetermined headway or distance to the next vehicle ahead so that the desired headway can be maintained or braking and acceleration provided to prevent collision. The radar may control the braking and acceleration automatically so that the traffic can be guided during poor visibility such as fog, falling snow or heavy rain. Specification 1,213,630 discloses the radar arrangement which may be used. As shown magnets A, B, C, D, E, F and G actuate selection of the radar on the vehicles. At A the radar of the vehicle is caused to interrogate alternately highway P1P3 and siding P1, P2, P3 codes and indicates that siding inlet P1 is approaching. The transponder on the vehicle continues to respond to the highway code only. When the vehicle enters the siding and passes magnet B the radar switches to emit only siding code, the responder only responds to the siding code and the inlet warning signal is switched off. The vehicle is then slowed down in response to transponder of any vehicle in front on the siding or to a fixed transponder located at the bus station. A vehicle which continues on the highway passes magnet C which switches the radar to only interrogate the highway radar code and to respond only to the highway code. When the vehicle on the highway reachs magnet D this causes the radar on that vehicle to respond alternately to highway and siding codes. The vehicles on the highway then become aware of the merging vehicle on the siding and adjust their headway to allow for a ghost vehicle or space corresponding to that required by the merging vehicle. At E the radar on the vehicle on the highway is switched so that it cannot distinguish between a vehicle on the highway or siding. At magnet F the radar on the vehicle in the siding starts to interrogate alternately the highway and siding codes but the transponder responds only to interrogation in the siding code. The siding vehicle then merges into the ghost position at P3 and when the vehicles pass magnet G the radar is switched to interrogate highway code and the transponder is also switched to operate only on highway code. If a vehicle has to be braked rapidly it gives a deceleration radar code which is equivalent to a stop light. Alternatively the ranging apparatus could be sonar apparatus.