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32-665: The Teign Valley line was a single-tracked railway line that ran from Heathfield to Exeter , via the Teign Valley , in Devon , England . It joined the South Devon main line at Exeter City Basin Junction. The line was open to passenger services between 1882 and 1958. The Teign Valley Railway Act 1863 ( 26 & 27 Vict. c. clix) was given royal assent in 1863 and the line opened on 9 October 1882, branching from

64-413: A crossing loop , crossing place , refuge loop or, colloquially, a hole ) is a place on a single line railway or tramway , often located at or near a station , where trains or trams travelling in opposite directions can pass each other. Trains / trams going in the same direction can also overtake, provided that the signalling arrangement allows it. A passing loop is double-ended and connected to

96-566: A bike trail can restrict a train corridor to a single track. Also reclaiming a railway corridor to use trains again limits the use of double tracks. The bike path is usually where the second track would be, and there may be fierce opposition by bikers and hikers. An example of a bike, single-track corridor is the E&;N Railway in Victoria, Canada. Passing loop A passing loop (UK usage) or passing siding (North America) (also called

128-450: A double track with signal boxes four minutes apart can allow up to 15 trains per hour in each direction safely, provided all the trains travel at the same speed. This hindrance on the capacity of a single track may be partly overcome by making the track one-way on alternate days. Long freight trains are a problem if the passing stretches are not long enough. Other disadvantages include the propagation of delays, since one delayed train on

160-487: A passing loop cannot be built. An extra parallel siding is often built at stations on refuge sidings so that two stopping trains can pass, and an extended catch point opposite the refuge siding may be added so as not to interfere with passing trains. If a crossing loop is several times the length of the trains using it, and is suitably signalled, then trains proceeding in opposite directions can pass (cross) each other without having to stop or even slow down. This greatly reduces

192-408: A radio system to set the points from a distance. The design of crossing loops may have to be modified where there are severe gradients that make it difficult for a train to restart from a stationary position, or where the terrain is unsuitable for a normal loop. A crossing loop on steep gradient may have catch points on the downhill end to reduce the impact of runaways. Since central operation of

224-538: A resurgence of traffic during the restrictions and petrol rationing after the Second World War however passenger trains were withdrawn in June 1958. This was five years before the publication of The Reshaping of British Railways which led to the closure of many similar routes. Flooding caused the line to be closed entirely between Christow and Exeter in 1961, following which the gradual withdrawal of freight saw

256-559: A single track will also delay any train waiting for it to pass. Also, a single track does not have a "reserve" track that can allow a reduced capacity service to continue if one track is closed. If a single-track line is designed to be used by more than one train at a time, it must have passing loops (also called passing sidings or crossing loops ) at intervals along the line to allow trains running in different directions to pass each other. These consist of short stretches of double track, usually long enough to hold one train. The capacity of

288-624: A single-track line is determined by the number of passing loops. Passing loops may also be used to allow trains heading in the same direction at different speeds to overtake. In some circumstances on some isolated branch lines with a simple shuttle service (such as the Abbey Line in Great Britain or L202 railway in Croatia) a single-track line may work under the "one train working" principle without passing loops, where only one train

320-541: A single-track railway to double track is called duplication or doubling; converting double track to single track is known as singling. A double-track railway operating only a single track is known as single-line working . Kirkby railway station (until 1977) and Ormskirk railway station (until 1970) were double-track railway , when they were converted into single-track railway with cross-platform interchange . Building bike trails on rail corridors has occurred in limited examples; however, developing rail rights of way for

352-421: Is a line which requires further development or a change in circumstances such as housing developments to make it viable. Single track (rail) Single track is significantly cheaper to build and maintain, but has operational and safety disadvantages. For example, a single-track line that takes 15 minutes to travel through would have capacity for only two trains per hour in each direction safely. By contrast,

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384-421: Is allowed on the line at a time. On single-track lines with passing loops, measures must be taken to ensure that only one train in one direction can use a stretch of single track at a time, as head-on collisions are a particular risk. Some form of signalling system is required. In traditional British practice (and countries using British practice), single-track lines were operated using a token system where

416-494: Is common in Russia and post-Soviet states. A disadvantage of the platform and through arrangement is the speed limits through the turnouts at each end. In the example layout shown, trains take the left-hand track in their direction of running. Low-speed turnouts restrict the speed in one direction. Two platform faces are needed, and they can be provided either at a single island platform or two side platforms (as shown). Overtaking

448-458: Is not normally possible at this kind of up-and-down loop as some of the necessary signals are absent. Crossing loops using up-and-down working are very common in British practice. For one thing, fewer signals are required if the tracks in the station are signaled for one direction only; also, there is less likelihood of a collision caused by signalling a train onto the track reserved for trains in

480-422: Is usually located on the main line. If passenger trains are relatively few in number, and the likelihood of two passenger trains crossing each other low, the platform on the loop line may be omitted. If the passenger train from one direction always arrives first, the platform on the loop line may also be omitted by extending the platform past the loop in that direction. The through road has straight track, while

512-561: The Moretonhampstead and South Devon Railway 's station at Heathfield, to Christow. In 1903 the line was extended by the Exeter Railway Company from Christow to a junction near Exeter St Thomas station. It served mineral quarries in the valley and had a passenger service. For a brief time there was an engine shed at Ashton. The mineral traffic that had provided much of the line's revenues was also its downfall, as

544-440: The approaching train. Some loops have the points in and out of the loop operated manually, albeit more recent examples have so-called self-restoring switches that allow trains to exit a loop without needing to change the points. Other forms of remote operation included centralized traffic control , in which a train controller changes points and signals from a remote office; and driver-operated points, which enable train crews to use

576-584: The available space for crossing loops is usually limited, they do not normally have an overlap (safety margin) between the starting signals and the end of the double line. In Australia, the Australian Rail Track Corporation (ARTC) policy provides for overlaps of about 500 m and 200 m respectively in an effort to avoid derailment or collision. Many crossing loops are designed to operate automatically in an unattended mode. Such loops may be track-circuited with home signals cleared by

608-485: The early days of railways in North America it was common to rely upon simple timetable operation where operators knew where a train was scheduled to be at a particular time, and so would not enter a single-track stretch when they were not scheduled to. This generally worked but was inflexible and inefficient. It was improved with the invention of the telegraph and the ability to issue train orders . Converting

640-593: The east of Longdown. The A38 road now occupies some of the route near to Chudleigh; the intersection at this point is named Chudleigh Station . A short section of the line in Exeter, known as the Alphington Spur , remains a siding for weekly scrap metal freight trains. Many of the stations and some of the line's infrastructure still exist: Reopening of the Teign Valley line was an option considered in

672-420: The first train to arrive must stop or move very slowly, while the second to arrive may pass at speed. If one train is too long for the loop it must wait for the opposing train to enter the loop before proceeding, taking a few minutes. Ideally, the shorter train should arrive first and leave second. If both trains are too long for the loop, time-consuming "see-sawing" (or "double saw-by") operations are required for

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704-451: The line finally close in 1967. The line followed a sinuous course from Heathfield to Exeter, which was the Up direction. From Ashton the line climbs considerably to Longdown, with a long stretch at 1 in 64. From Longdown the line falls at 1 in 58 for several miles. There were two tunnels at Longdown; Culver Tunnel (248 yards, 227 m) to the west and Perridge Tunnel (836 yards, 764 m) to

736-408: The main track at both ends, though a dead end siding known as a refuge siding , which is much less convenient, can be used. A similar arrangement is used on the gauntlet track of cable railways and funiculars , and in passing places on single-track roads . Ideally, the loop should be longer than all trains needing to cross at that point. Unless the loop is of sufficient length to be dynamic ,

768-523: The opposing direction. In France, they often use spring switches and the speed is equally restricted in both directions. The speed restriction in one direction can be eliminated with higher-speed turnouts, but this may require power operation, as the longer and heavier high-speed turnouts may be beyond the capability of manual lever operation. Refuge sidings are used at locations with gradients too steep for heavy freight trains or steam haulage to depart from conventional passing loops, or confined spaces where

800-472: The platform road has low-speed turnouts at either end. A possible advantage of this layout is that trains scheduled to pass straight through the station can do so uninterrupted; they do not have to reduce their speed to pass through the curve. This layout is mostly used at local stations where many passenger trains do not stop. Since there is only one passenger platform, it is not convenient to cross two passenger trains if both stop. This type of passing loop

832-454: The points and signals from a single signal box is convenient, and since there are practical limits for the distance to these points and signals, crossing loops can have a system-wide effect on train sizes. Line capacity is partly determined by the distance between individual crossing loops. Ideally these should be located at inverse -integer intervals along the track by travel time. The longest section between successive crossing loops will, like

864-486: The quarries provided roadstone for Devon's expanding and improving road network. In the 1920s and 1930s, the new motor bus services meant that passenger traffic dwindled. The mineral traffic soon followed. Meanwhile, the Great Western Railway placed camp coaches in some of the stations providing holiday accommodation. A small station was opened at Chudleigh Knighton Halt on 9 June 1924. The line saw

896-467: The time lost by the first train to arrive at the crossing loop for the opposing train to go by. This system is referred to as a dynamic loop. For example, the Windermere branch line will be getting one to permit a 2tph service pattern. Some railways fit catch points at the ends of crossing loops so that if a train overruns the loop, it is derailed rather than collide with an opposing train. Since

928-594: The train driver had to be in possession of a token in order to enter a stretch of single track. Because there was only one unique token issued at any one time for each stretch of single track, it was impossible for more than one train to be on it at a time. This method is still used on some minor lines but in the longest single-track lines in Britain (e.g. the Highlands of Scotland) this has been superseded by radio communication, known as Radio Electronic Token Block . In

960-416: The trains to cross (see Tawa railway station ). On railway systems that use platforms , especially high-level platforms, for passengers to board and disembark from trains, the platforms may be provided on both the main and loop tracks or possibly on only one of them. The main line has straight track, while the loop line has low-speed turnouts at either end. If the station has only one platform, then it

992-517: The wake of widespread disruption caused by damage to the mainline track at Dawlish by coastal storms in February 2014. The Transport Secretary, Patrick McLoughlin, ordered a review of alternative inland rail routes but no decision to reopen any line was forthcoming. The Campaign for Better Transport released a report in January 2019 which described the line as their "Priority 2" for reopening, this

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1024-420: The weakest link in a chain, determine the overall line capacity. Long and short trains can cross at a short loop if the long train arrives second but leaves first. It is best if all crossing loops are longer than the longest train. Two long trains can cross at a short loop using a slow so-called see-saw process, which wastes time. Countries generally have a principle on which side trains shall meet, either on

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