201103 – Moore – Understanding Signalling Overlaps

Signalling principles use the Overlap as an additional protection for the hazard of a train not stopping at a signal at danger. This paper details the different types of overlaps, how they are determined and how they can be applied in a signalling design for a specific network. Network characteristics for Urban areas are typically different to those of Interurban areas and country areas often resulting in different application of overlaps.

The overlaps become an important part of the signal locking principles. This ensures the separation of
trains in complex situations.