Headshunt: Difference between revisions
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[[File:Headshunt.png|thumb|450px|Diagram of a headshunt and run-round loop]] |
[[File:Headshunt.png|thumb|450px|Diagram of a headshunt and run-round loop]] |
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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. It is commonly used to haul wagons onto a siding, or at a terminal station to prepare for a return journey.<ref>{{Railway Dictionary|page=298}}</ref> |
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. It is commonly used to haul wagons onto a siding, or at a terminal station to prepare for a return journey.<ref>{{Railway Dictionary|page=298}}</ref> This process is known as "running round a train".<ref>{{Ellis' Railway Encyclopaedia|page=307}}</ref> |
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Although a common procedure for [[passenger train]]s when the majority of them were locomotive-hauled, the manoeuvre is now becoming rarer on public service railways.{{Citation needed|date=August 2009}} Increased use of [[multiple unit]] and [[Push-pull train|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.{{Citation needed|date=August 2009}} However, on [[heritage railway]]s run-round loops are still usually more or less necessary 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. This practice is still very common on Intercity services in [[Victoria (Australia)|Victoria, Australia]]. |
Although a common procedure for [[passenger train]]s when the majority of them were locomotive-hauled, the manoeuvre is now becoming rarer on public service railways.{{Citation needed|date=August 2009}} Increased use of [[multiple unit]] and [[Push-pull train|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.{{Citation needed|date=August 2009}} However, on [[heritage railway]]s run-round loops are still usually more or less necessary 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. This practice is still very common on Intercity services in [[Victoria (Australia)|Victoria, Australia]]. |
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Revision as of 16:09, 11 January 2018
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A headshunt (or escape track in the United States) is a short length of track provided to release locomotives at terminal platforms, or to allow shunting to take place clear of main lines.
Terminal headshunt
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 (assuming, of course, that it is a locomotive equipped to run in either direction; for older, one-way equipment such as steam locomotives and cab unit locomotives, a wye or turntable needs to be provided to physically turn the engine around, as well as a run-around track).
Reversing headshunt
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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.
Shunting neck
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.
Run-round
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. It is commonly used to haul wagons onto a siding, or at a terminal station to prepare for a return journey.[1] This process is known as "running round a train".[2]
Although a common procedure for passenger trains when the majority of them were locomotive-hauled, the manoeuvre is now becoming rarer on public service railways.[citation needed] 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.[citation needed] However, on heritage railways run-round loops are still usually more or less necessary 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. This practice is still very common on Intercity services in Victoria, Australia.
Examples
Stations which used to have run-rounds include:
- UK
- Australia
- Murwillumbah railway station, now closed
- Toronto railway station, New South Wales, now closed
- Cronulla railway station, had run-round, but never had locomotives
- Newcastle railway station, New South Wales, now closed; run-round on Platform 1&2, not on Platform 3&4
Stations which still have run-rounds include:
- UK
- Germany
- Australia
- Canberra railway station
- Many stations in Victoria have working run-rounds used by Intercity locomotive hauled services. These services are hauled by V/Line's N Class Locomotives and are yet to be replaced by DMU Railcars. Stations where this practise takes place include Warrnambool, Bairnsdale and Albury. Run-rounds are also used on commuter services hauled by N Class or P Class Locomotives at stations such as South Geelong & Marshall.
No loop
If a terminal station has or no longer has a run-round loop, trains are restricted to multiple units or Top and Tail trains.
Relay engines
Sometimes a terminal station has no run-round loops, the absence of which is overcome by coupling a relay engine to the rear to power the next out bound trip. The original engine of the arriving train shunts to the relay engine siding where it awaits the arrival of the second train, and so on. Examples in steam days include Fenchurch Street and Kingsgrove.
References
- ^ Jackson, Alan A. (2006). The Railway Dictionary (4th ed.). Sutton Publishing Ltd. p. 298. ISBN 0-7509-4218-5.
- ^ Ellis, Iain (2006). Ellis' British Railway Engineering Encyclopaedia. Lulu.com. p. 307. ISBN 978-1-8472-8643-7.