scope:

This module applies to: 

a) signal engineering maintainers, designers, works installers and testers. 

b) all new axle counter installations and to alterations at existing axle counter installations.

This module is based on axle counters that form train detection sections by counting the number of wheels into and out of those sections. Axle counter wheel detectors may be used in treadle mode, but that application is not in the scope of this module.

Free-standing axle counting equipment that is wholly contained within subsystems (such as overlay train detection provided for level crossings) is excluded from the scope of this module. It is not a requirement of the level crossing subsystem for the signaller to know where the train is.

Axle-detecting devices that are not necessary for the interlocking of routes nor the clearance of signal aspects but are used to indicate train position to signallers,should not be configured as axle counters, such as SPAD prediction at level crossings.

This module applies irrespective of the type of technology used.

Purpose

This module forms part of the Signalling Principles Handbook (NR/L2/SIG/30009). 

This module details the system application principles for axle counter systems including the methods of reset following failure and provisions for engineering work and for special trains which may fail to count correctly.