Method of reducing an overlap in a railway signalling system

Abstract

Railway signalling system 1 comprises two railway lines A,B (each having a respective pair of first and second signals 2,6 and 4,8) and a set of points 101 enabling trains to cross from the first onto the second railway line and travel towards a destination signal 10 thereon. An overlap is reduced by maintaining the first signal 2 at a red aspect; setting a first route R1 along the second railway line up to its second signal 8 whilst maintaining a full overlap FOL that extends beyond the points; and determining the speed of a train as it approaches said signal along the first route. If the train speed is below a first threshold, the overlap is reduced to a restricted overlap ROL that stops short of the points, a second route R2 is set on the second railway line and a third route R3 is set on the first railway line from its second signal 6 past the points to the destination signal. Otherwise the full overlap is maintained and signals 2 and 8 are both red. Optionally, if the train speed is below a second, lower threshold, the overlap is released. The speed may be determined using a trackside RADAR, LiDAR or wheel sensor (e.g. axle-counter head).

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