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A single-track railway is a railway where trains traveling in both directions share the same track. Single track is usually found on lesser-used rail lines, often branch lines, where the level of traffic is not high enough to justify the cost of constructing and maintaining a second track.
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, 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 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.
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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 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 is allowed on the line at a time.
Refuge sidings also allow passing of trains on a single-track railway.
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 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 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 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 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. [1]
The European microstates of Liechtenstein and Vatican City each have only one single-track railway line: the Feldkirch–Buchs railway and the Vatican railway, respectively.
A funicular is a type of cable railway system that connects points along a railway track laid on a steep slope. The system is characterized by two counterbalanced carriages permanently attached to opposite ends of a haulage cable, which is looped over a pulley at the upper end of the track. The result of such a configuration is that the two carriages move synchronously: as one ascends, the other descends at an equal speed. This feature distinguishes funiculars from inclined elevators, which have a single car that is hauled uphill.
A railroad switch (AE), turnout, or [set of] points (CE) is a mechanical installation enabling railway trains to be guided from one track to another, such as at a railway junction or where a spur or siding branches off.
In railroad structures and rail terminology, a wye or triangular junction is a triangular joining arrangement of three rail lines with a railroad switch at each corner connecting to the incoming lines. A turning wye is a specific case.
The City Loop is a piece of underground commuter rail infrastructure in the central business district (CBD) of Melbourne, Victoria, Australia.
The Eastern Suburbs & Illawarra Line is a commuter railway line on the Sydney Trains network in the eastern and southern suburbs of Sydney. The line was constructed in the 1880s to Wollongong to take advantage of agricultural and mining potentials in the Illawarra area. In March 1926, it became the first railway in New South Wales to run electric train services.
In railway signalling, a token is a physical object which a train driver is required to have or see before entering onto a particular section of single track. The token is clearly endorsed with the names of the section to which it belongs. A token system is more commonly used for single lines because of the greater risk of collision in the event of a mistake being made by a signaller or traincrew than on double lines.
Centralized traffic control (CTC) is a form of railway signalling that originated in North America. CTC consolidates train routing decisions that were previously carried out by local signal operators or the train crews themselves. The system consists of a centralized train dispatcher's office that controls railroad interlockings and traffic flows in portions of the rail system designated as CTC territory. One hallmark of CTC is a control panel with a graphical depiction of the railroad. On this panel, the dispatcher can keep track of trains' locations across the territory that the dispatcher controls. Larger railroads may have multiple dispatcher's offices and even multiple dispatchers for each operating division. These offices are usually located near the busiest yards or stations, and their operational qualities can be compared to air traffic towers.
The Highland Main Line is a railway line in Scotland. It is 118 mi (190 km) long and runs through the central Scottish Highlands, mainly following the route of the A9, and linking a series of small towns and villages with Perth at one end and Inverness at the other. Today, services between Inverness and Edinburgh, Glasgow and London use the line. At Inverness the line connects with the Far North Line, the Aberdeen-Inverness Line and the Kyle of Lochalsh Line. Since the line is not electrified all trains are diesel-powered.
Radio Electronic Token Block is a system of railway signalling used in the United Kingdom. It is a development of the physical token system for controlling traffic on single lines. The system is slightly similar to North American direct traffic control, which unlike RETB does not have a cab display unit.
Gauntlet track or interlaced track, also gantlet track (AE) is an arrangement in which railway tracks run parallel on a single track bed and are interlaced in such a way that only one pair of rails can be used at any time. Since this requires only slightly more width than a single track, all rails can be carried on the same crossties/sleepers. Trains run on the pair of rails appropriate to their direction, track gauge or loading gauge.
A double-track railway usually involves running one track in each direction, compared to a single-track railway where trains in both directions share the same track.
A passing loop or passing siding 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 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.
A balloon loop, turning loop, or reversing loop allows a rail vehicle or train to reverse direction without having to shunt or stop. Balloon loops can be useful for passenger trains and unit freight trains.
The Dry Creek–Port Adelaide railway line is an eight-kilometre east–west freight railway line running through Adelaide's north-western suburbs. The line is managed by the Australian Rail Track Corporation (ARTC) and is an important link between Port Adelaide, Pelican Point and the main interstate rail routes which link Adelaide with Melbourne, Perth, Darwin and Sydney. Prior to 1988, a limited local passenger service operated, stopping at five intermediate stations along the line. Since May 1988, the line has been freight-only.
Signalling block systems enable the safe and efficient operation of railways by preventing collisions between trains. The basic principle is that a track is broken up into a series of sections or "blocks". Only one train may occupy a block at a time, and the blocks are sized to allow a train to stop within them. That ensures that a train always has time to stop before getting dangerously close to another train on the same line. The block system is referred to in the UK as the method of working, in the US as the method of operation, and in Australia as safeworking.
Opened on the 8th of October 1998, the only high-speed rail in Norway, on the railways of Norway is on Gardermobanen, a 64 kilometer line between Oslo Central Station and Eidsvoll via Oslo Airport. The main service on this route is Flytoget, commuting between Oslo Airport and the metropolitan areas of Oslo at speeds of up to 210 km/h (130 mph). It was extended westwards to include the city of Drammen in 2008, though not at high speed. The high-speed section is also used by express and regional trains between Oslo and Eidsvoll.
The Coventry to Leamington Line is a railway line linking the city of Coventry with the town of Leamington Spa. The line was opened in 1844 by the London and Birmingham Railway, as far as Milverton. The line was extended to Leamington Spa Avenue in 1851. A connecting line to Berkswell opened in 1884.
Automatic block signaling (ABS), spelled automatic block signalling or called track circuit block (TCB) in the UK, is a railroad communications system that consists of a series of signals that divide a railway line into a series of sections, called blocks. The system controls the movement of trains between the blocks using automatic signals. ABS operation is designed to allow trains operating in the same direction to follow each other in a safe manner without risk of rear-end collision.
A pocket track, tail track, or reversing siding is a rail track layout which allows trains to park off the main line. This type of track layout differs from a passing loop in that the pocket track is usually located between two main lines, rather than off to the side. Found primarily on metro systems, rapid transit light rail networks, and tramways, a pocket track allows certain trains or trams to change direction, even on lines with high traffic flow, whilst others continue through the station.
The Carlingford railway line is a former heavy rail line in Sydney, New South Wales, Australia, which now largely forms part of the Parramatta Light Rail. It was opened from Clyde to Subiaco in January 1885, then by means of the construction of a bridge across the Parramatta River, to Carlingford in April 1896. It closed on 5 January 2020 with most of the line undergoing conversion to light rail, while a short section of the line was retained for use by Sydney Trains.
