The New Zealand Railways Magazine, Volume 6, Issue 2 (June 1, 1931)
Automatic Train Control
Automatic Train Control.
Various types of automatic train control are employed on the Home railways, a leader in this endeavour being the Great page 20 Western. This undertaking has for some time utilised automatic train control on certain stretches of track, and now the whole of its principal main-lines are to be so equipped. The plan involves the equipment of 1,758 miles of track and 2,000 locomotives with the Company's own arrangement of automatic control. On completion of the new installation, the Great Western will have equipped 2,130 miles of track and 2,334 engines for automatic train control.
The system gives to the driver audible warning of the state of the signal, and in the event of a danger signal being passed, automatically stops the train before it reaches the next signal. In practice the audible warning is given to the driver when his train is approaching a distant signal in the danger position. In the event of this warning being disregarded, the brakes are automatically applied so as to ensure the train being pulled up before the next stop signal is reached. Another and distinctive audible indication is provided on the locomotive when the distant signal shows “line clear.” For the indication “signal at danger” a siren is sounded, and for the indication “line clear” a bell is rung. The apparatus fixed to the track for operating the audible signals consists of an immovable ramp, forty feet long, placed between the running rails, taking the form of a steel inverted T-bar mounted on a baulk of timber. At its highest point the ramp is four inches above rail level, and it is connected with a switch in the signalbox attached to a lever controlling the distant signal. On the locomotive there is affixed a contact shoe, an electrically-controlled brake valve and siren combined, and an electric bell. The contact shoe is secured on the centre line of the locomotive, projecting to within two and a half inches above rail level.