This is currently estimated to be around four times that of an SSI, giving it the capability to control over 300 Signalling Equivalent Units (SEUs).
A Westlock system is divided into a number of components, called the Central Interlocking Processor (CIP), Trackside Interface (TIF) and Technicians Workstation (TW).
The hardware used by the TIF and CIP is similar, based around a 2-out-of-3 architecture, whereby all safety-critical functions are performed in three separate processing lanes and the results voted upon.
This provides some fault tolerance whereby a single module can fail and the system can continue operating in 2-out-of-2 mode.
It provides a graphic interface which includes a map of the area of Railway under control and operates on an industrial PC platform.