A type of Lockout SystemA system which allows a person requiring access to the track to provide personal protection by restricting or preventing the signalling of trains. that allows a PatrolmanA person who patrols/inspects a section of line., with the permission of
the SignallerA person responsible for the operation of the Signalling System, to safely control the passage and regulation of trains, usually located in a Signal Box., to prevent the signalled movement of traffic, for example, in
one direction only on a Bi-Directional LineA line on which the signalling permits trains to be signalled normally in either direction. See Bi-Directional Signalling.