Detecting the occupancy of track blocks is one of the primary applications of wheel dec). Sensors are fastened to the rail at the ‘check-in’ and ‘check-out’ points at either end of a section of track creating a ‘block’. The WCU collects waveforms from the sensors and sends digital data to the EVU for processing. The EVU counts the axles of the train as it enters the block, and again as it leaves, based on the output of the sensors. The EVU will indicate that the block is ‘occupied’ when the first axle passes the ‘check-in’ point. Once the EVU has counted the same number of axles leaving the ‘check-out’ point as it counted at the ‘check-in’, the block is deemed vacant and safe for another train to enter.
Axle-counting-based block occupancy systems are used as an alternative to fixed blocks handled with track circuits. They are also an efficient and effective backup solution for more sophisticated moving block systems common with communications-based train control (CBTC).
Our axle-counting system relies on two sensors at the check-in and check-out points. This provides the data for our unique majority logic algorithm which ensures the highest level of accuracy.