Abstract: This invention provides automatic longitudinal control of vehicles on highways, including speed control and protection against collision. The invention also provides for lane changing, following highway directional changes, route control, and transitions between the operator-controlled and the automatically controlled states. The invention is ideally configured to be employed jointly and cooperatively with previously developed means of automatic lateral control. Groups of permanent magnets are embedded in the highway surface at regular intervals. Permanent magnet sensors are installed in vehicles so that proximity and polarity indications of embedded magnets are obtained as a vehicle proceeds along the highway.

Abstract: Safe separation distances between automatically controlled vehicles moving at short headways on a guideway are maintained through the cooperative action of a block control system and reflectometer (radar) and transponder (beacon) intervehicle distance measuring equipment installed in vehicles. A reflectometer determines distance to a leading vehicle through measurement of the delay between a transmitted signal and a received signal relayed by a transponder in the leading vehicle. A transmission line acts as the medium of transmission. Problems associated with non-transponder-equipped reflectometers are obviated. In the event of transponder malfunction, the block control system maintains backup safety regardless of transponder activity in other vehicles. Exessively short block lengths generally required for short-headway maintenance by block control systems are not required.