Dual track occupancy signalling system - measures train velocity for correspondingly delayed release of track-free signal to obtain added safety margin

摘要

The dual track occupancy system, for short single or multiple line track sections, uses a counter associated with switches at the beginning and end of the track section operated by passage of the rail vehicle. A track occupancy signal is supplied upon reaching an initial count after triggering by the train entering the track section. Two switches are used at either end of the track section, spaced to define a measuring section for determining the vehicle speed. The counter only responds to the switch signals to give a track free signal when the speed is below a given threshold, in which case the track free signal is supplied after a timed delay. The system provides an added safety margin independent of the train speed.