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The little friend in the corner

The ATC pick-up shoe shown on a typical ramp between two running rails. The cab equipment is on the extreme right of this picture.

The “Friend” is the Great Western Railway (GWR) Automatic Train Control system. Known as ATC, it was first used on the Henley-on-Thames branch in 1906. It’s an audible warning system to tell footplate staff the state of the signals ahead. Placed on the driver’s side of the cab (the right-hand side on the GWR), it was particularly useful in poor weather and light conditions. Curved ramps in the track interacted with a pick-up shoe on the locomotive. When a distant (yellow) signal was pulled “off” for a clear signal ahead, the ramp became electrified, the locomotive shoe passing over it picked this up and the “all clear” bell sounded on the cab apparatus. If the distant (yellow) signal was “on”, denoting caution and a danger (red) signal further ahead, the ramp was electrically dead and a warning steam whistle sounded in the cab. From 1913 the steam whistle was replaced by an air siren. The sound of the siren coincided with a partial brake application which couldn’t be ignored by the driver and which he had to cancel in order to proceed. The bell for a clear signal ahead was a great comfort for footplate staff when running in fog, falling snow and at night. Trains still ran to time, even in the poorest conditions of visibility.

The ATC cab equipment showing the round brass bell and the siren cancelling switch on the side of the equipment box.

November 1939 saw the completion of the major task of fitting the system to all of the GWR’s mainline routes (2,852 miles). For publicity, GWR Driver Godfree was chosen to host a journalist on his footplate from Paddington to Reading to demonstrate the system. As the bell rang, he said, “We had none of this when I was a young fireman, but I shouldn’t be without it now. Driving with this system isn’t half the strain it used to be. And it’s grand, of course, in dirty weather. It means you can’t go on when you ought to stop. Even if you were suddenly paralysed, even if you and your fireman fell off the engine the thing would go on working and the train would stop at a danger signal. I have never once known it go wrong.”

Other railway companies developed their own cab warning systems, but running in conditions such as fog and falling snow continued to rely on signalling staff using signal box equipment to place explosive detonators on rails to alert drivers to adverse signals. Alternatively, permanent way staff with lamps and flags were stationed in “fogging hut” sentry boxes placing detonators on rails by key signals when “caution” and “danger” were indicated.

An explosive warning detonator secured with lead clips on a railhead. Thousands of these were used in bad weather and in cases of mishaps. The “bang” had to be clearly audible in the noisy cab.

The ATC system lasted until the ramps were removed in the mid-1970s. It was replaced by the British Railways Automatic Warning System (AWS) which was developed in the 1950s and became widely installed in the 1960s and early 1970s. There then followed Automatic Train Protection (ATP), deemed to be too expensive, and this was overtaken by the current Train Protection and Warning System (TPWS) which may last until the 2040s. In time, new signalling systems using in-cab computers fed with speed and warning data transmitted from lineside equipment and track balises will replace TPWS.

Mike Peart

Mike Peart is a former railwayman on British Railways (Western Region). He is co-author of Volumes 3 (Freight Marshalling Yards), 4 (Level Crossings) and 5 (Train Detection and Control) of the “History & Development of Railway Signalling in the British Isles” series, and Trains of Hope”, all published by The Friends of the National Railway Museum. He’s been an active Friend of the NRM since 1994 and was one of the four “schoolboy” founder members of the Great Western Society (Didcot Railway Centre) in 1961.

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