Signalling – What you'll do

Maintenance engineering technicians (signalling) may work maintaining or fault finding on existing signalling installations – this includes such tasks as taking and recording electrical and mechanical values of equipment. The important thing is keeping a good attention to detail and working very safely. Because of the location of signals and signal boxes, you'll often be outdoors and will need to be physically fit to access the circuitry and check the signal.

The main areas of focus for you will be:

Track Circuits

These are activated when a train moves along the track and an electrical current moves along the rails. This shorts out the circuit and switches a relay. This, in turn, makes its way back to the signaller to show where the train is and control the signalling systems.

Axle Counters

Does what it says in the title. These count the axles of the train (in a similar way to the track circuits) to determine where the train is.


These switch the rails to divert trains from one track to another.


Signals tell the driver the status of the line ahead; and as well as providing a telephone for contact with the signaller, they also have an Automatic Warning System (AWS) and a Train Protection Warning System (TPWS) that apply the brakes on a train in an emergency.

Locations/Relay Rooms/REBs

All the equipment is normally housed along the trackside in what we call locations. A large amount of equipment is often kept in a Relay Room or Re-locatable Equipment Building (REB).

Signal Boxes/Signalling Control Centres

This is where the signallers that control the movement of trains work. The scale of what they do varies greatly: it could be the operation of a mechanical lever frame, or working at one of the Electronic Control Centres covering 100 miles of route or more.