A terminal headshunt is a short length of track that allows a locomotive to uncouple from its train, move forward, and then run back past it on a parallel track. Such headshunts are typically installed at a terminal station to allow the locomotive of an arriving train to move to the opposite end of (in railway parlance, 'run around') its train, so that it can then haul the same train out of the station in the other direction.
Found primarily on metro systems, rapid transit light rail networks, and tramways, a reversing headshunt allows certain trains or trams to change direction, even on lines with high traffic flow, whilst others continue through the station. Typically there will be two running lines, one for each direction of travel, and the headshunt will be positioned between the two running lines, linked to both by points. Although most trains will pass through the station and continue in the same direction, an individual train may be directed into the reversing headshunt, before exiting onto the other running line, in the opposite direction of travel. This procedure allows a greater frequency of trains on a city-centre section of the line, and reduced frequency on the suburban sections, by allowing certain trains to shuttle back and forth only on the city centre part, using the reversing headshunts to change direction within the flow of trains.
The term headshunt may also refer to shunting neck or shunt spur: a short length of track laid parallel to the main line for the purpose of allowing a train to shunt back into a siding or rail yard without occupying the main running-line.
A run-round loop (or run-around loop) is a track arrangement that enables a locomotive to attach to the opposite end of the train. This process is known as "running round a train". It is commonly performed to haul wagons onto a siding, or at a terminal station to prepare for a return journey.
Although a common procedure when the majority of trains were locomotive-hauled, the manoeuvre is now comparatively rare on public service railways. Increased use of multiple unit and push-pull passenger services avoids the requirement for dedicated track and the need for railway staff to detach and reattach the locomotive at track level. However, many heritage railways (in the UK, at least) deliberately incorporate run-round loops at each end of the running line, partly because train services are usually locomotive-hauled, and partly because the run-round operation gives added interest to visitors.
Stations which used to have run-rounds include:
- St Ives (UK).
- Toronto railway station, New South Wales - now closed.
- Cronulla railway station - had run round, but never had locomotives, now no run round.
- Newcastle railway station, New South Wales - run-round on Platform 1&2, not on Platform 3&4.
Stations which still have run-rounds include:
- Canberra and
- Marshall railway station
- Matlock Riverside railway station, now closed
- Murwullimbah, now closed
- Rowsley South railway station
- South Geelong railway station
- Weymouth railway station
- Fort William railway station
- Morecambe railway station
- Hagen Hauptbahnhof
- Ellis, Iain (2006). Ellis' British Railway Engineering Encyclopaedia. Lulu.com. p. 307. ISBN 978-1-8472-8643-7.
- Jackson, Alan A. (2006). The Railway Dictionary (4th ed.). Sutton Publishing Ltd. p. 298. ISBN 0-7509-4218-5.