What kinds of axle counters does IR use?
[5/99] Axle counters are widely used by IR to ensure that all wagons or coaches of a train have indeed passed a given point — out of a block section, out of the station limits, out of yard limits, other point zones, etc. (‘last vehicle proving’, ‘block proving’, or ‘block verification’, serving the same purpose as the visual ‘Last Vehicle Check’ or LVC that is done otherwise). Axle counters may be of the single or multiple entry type. Axle counters today are mostly of the electronic variety. They use piezoelectric sensors on the tracks, which are triggered by the weight of a pair of wheels moving over them. Older models with electromechanical treadles actuated by the wheels of a passing train are also seen, as are some variants which use photoelectric detectors or magnetic detectors (using the Hall effect to sense the perturbation of magnetic flux) to count axles. The ‘counting’ is today usually done by digital circuits (‘SSDAC’ = solid-state digital axle counter, also generically term
