Train control is carried out in a train control centre (train operations centre).

Typically, a train controller decides when to intervene on a train's timetabled movement in response to incidents such as late running, accidents or a rolling stock/track maintenance requirements and advises the train controller.

A signal controller manipulates train movements to achieve the train controller's decision by remotely operating the signalling equipment in the field.

All decisions are only effected if the interlocking determines that the intervention is safe. The interlocking and the signalling equipment in the field are the safety-critical signalling system.

The system that relays vital and non-vital information is the signalling communications system.