UK railway signalling

Network Rail two-aspect colour-light railway signal set at danger

The railway signalling system used across the majority of the United Kingdom rail network uses lineside signals to control the movement and speed of trains.

The modern-day system mostly uses two, three, and four aspect colour-light signals using track circuit – or axle counter – block signalling.[1][2] It is a development of the original absolute block signalling that is still being used on many secondary lines. The use of lineside signals in Britain is restricted to railways with a maximum speed limit of up to 125 miles per hour (201 km/h). This is the maximum speed at which the train can travel safely using line-side signalling; if the train runs any faster, it will not be possible for the train driver to safely read colour-light signalling. Trains operating at speeds faster than 125 mph (for example on High Speed 1) use an in-cab signalling system that automatically determines and calculates speed restrictions.

  1. ^ "Track circuit block regulations". RSSB. Retrieved 2 September 2023.
  2. ^ "Railsigns.uk - Track Circuit Block". Retrieved 7 March 2017.