54-466: The Mering–Weilheim railway (German: Ammerseebahn ) is a 54 km long single-tracked main line in the provinces of Swabia and Upper Bavaria in southern Germany. It runs from Mering near Augsburg via Geltendorf to Weilheim and is listed by the Deutsche Bahn as Kursbuchstrecke 985. The Mering–Geltendorf–Schondorf (29.77 km) and Weilheim–Dießen (13.07 km) sections were
108-457: A double track and often contain multiple parallel tracks. Main line tracks are typically operated at higher speeds than branch lines and are generally built and maintained to a higher standard than yards and branch lines. Main lines may also be operated under shared access by a number of railway companies, with sidings and branches operated by private companies or single railway companies. Railway points (UK) or switches (US) are usually set in
162-695: A railway is a track that is used for through trains or is the principal artery of the system from which branch lines , yards , sidings , and spurs are connected. It generally refers to a route between towns, as opposed to a route providing suburban or metro services. It may also be called a trunk line, for example the Grand Trunk Railway in Canada, or the Trunk Line in Norway. For capacity reasons, main lines in many countries have at least
216-576: A single-track railway where trains in both directions share the same track. In the earliest days of railways in the United Kingdom, most lines were built as double-track because of the difficulty of co-ordinating operations before the invention of the telegraph . The lines also tended to be busy enough to be beyond the capacity of a single track. In the early days the Board of Trade did not consider any single-track railway line to be complete. In
270-550: A spiral . At Saunderton , England, what became the London-to-Birmingham main line of the Great Western Railway in 1909 was initially part of a single-track branch line from Maidenhead . Down trains follow the route of the old branch line, while up trains follow a more gently graded new construction through a tunnel. This scheme avoided the cost of a new double-track tunnel. Directional running
324-416: A double line might have to be shut down to avoid collisions with trains on those adjacent tracks. These are a form of crossing loop, but are long enough to allow trains approaching each other from opposite directions on single-track lines to cross (or pass) each other without reducing speed. In order for passing lanes to operate safely and effectively, trains must be timetabled so that they arrive at and enter
378-526: A horseshoe curve at 1 in 75 gradient, while the shorter downhill track follows the original single track at 1 in 40 grades. A similar arrangement to Frampton could not be adopted between Rydal and Sodwalls on the Main Western railway line because the 1 in 75 uphill track is on the wrong side of the 1 in 40 downhill track, so both tracks follow the 1 in 75 grade. Another example is at Gunning . Between Junee and Marinna, New South Wales , Australia
432-627: A major bottleneck. For Berlin Stadtbahn the two northern tracks are local S-Bahn and the two other for faster trains. The most notable example of quadruple track in the United States, and perhaps the only four-track section of mainline therein, was the Pennsylvania Railroad 's main corridor through the heart of Pennsylvania around the famous Horseshoe Curve . This line is now owned by Norfolk Southern. Other examples include
486-596: A second tunnel. An exception is the Hoosac Tunnel , which was duplicated by enlarging the bore. To reduce initial costs of a line that is certain to see heavy traffic in the future, a line may be built as single-track but with earthworks and structures designed for ready duplication. An example is the Strathfield to Hamilton line in New South Wales , which was constructed as mainly single-track in
540-565: A third track signalled in both directions, so that two tracks are available in the peak direction during rush hours. Triple track is used in some parts of the New York City Subway and on the Norristown High-Speed Line to add supplemental rush-hour services. The center track, which serves express trains, is signalled in both directions to allow two tracks to be used in the peak direction during rush hours;
594-412: A third track was opened between Whittingham and Branxton in 2011 and Branxton to Maitland in 2012 to equalize the headway in both directions for heavy coal traffic. Triple track could be a compromise between double-track and quad-track ; such a system was proposed south of Stockholm Central Station , but was cancelled in favor of Citybanan . In Melbourne and Brisbane several double track lines have
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#1732776251349648-428: A train failure, or for a fast train to overtake a slow train. Most crossing loops are not regarded as double-track even though they consist of multiple tracks. If the crossing loop is long enough to hold several trains, and to allow opposing trains to cross without slowing down or stopping, then that may be regarded as double-track. A more modern British term for such a layout is an extended loop. The distance between
702-415: Is an example of a duplication line that was reduced to single-track in most locations, but has since undergone re-duplication in many places between Baltimore and Philadelphia when CSX increased freight schedules in the late 1990s. Also: Some lines are built as single-track with provision for duplication, but the duplication is never carried out. Examples are: When the capacity of a double-track railway
756-979: Is called duplication or doubling , unless the expansion is to restore what was previously double track, in which case it is called redoubling . The strongest evidence that a line was built as single-track and duplicated at a later date consists of major structures such as bridges and tunnels that are twinned. One example is the twin Slade tunnels on the Ilfracombe Branch Line in the UK. Twinned structures may be identical in appearance, or like some tunnels between Adelaide and Belair in South Australia , substantially different in appearance, being built to different structure gauges . Tunnels are confined spaces and are difficult to duplicate while trains keep on running. Generally they are duplicated by building
810-487: Is in excess of requirements, the two tracks may be reduced to one, in order to reduce maintenance costs and property taxes. In some countries this is called singling . Notable examples of this in the United Kingdom occurred on the Oxford–Worcester–Hereford, Princes Risborough–Banbury and Salisbury–Exeter main lines during the 1970s and 1980s. In all these cases, increases in traffic from the late 1990s have led to
864-486: Is now catenary between Geltendorf and Augsburg. This excludes the few trains that, until the end of 2008, used to run only between Geltendorf and Augsburg in the morning and evening and were therefore hauled by electrics. A closure of this gap in the electrified network is planned in the longer term. The long waits at some of the crossing stations and irregular services meant that travel on the Ammersee Railway
918-515: Is quadruple tracked in most portions south of New Haven, but also has a few triple-track segments. The Metra Electric District is quadruple-tracked on most of the main line north of Kensington/115th Street station , with local trains running in the center two tracks, and express trains on the outer two tracks. Outside the United States the Chūō Main Line is an example of a modern, heavily utilized urban quadruple track railway. Quadruple track
972-557: Is two separate lines operationally combined to act as a double-track line by converting each line to unidirectional traffic. An example is in central Nevada , where the Western Pacific and Southern Pacific Railroads , longtime rivals who each built and operated tracks between northern California and Utah , agreed to share their lines between meeting points near Winnemucca and Wells , a distance of approximately 180 miles (290 km). Westbound trains from both companies used
1026-602: Is used in rapid transit systems as well: throughout the New York City Subway , the Chicago "L" 's North Side Main Line , and SEPTA 's Broad Street Line in the United States, and on the London Underground in the United Kingdom. The two tracks of a double-track railway do not have to follow the same alignment if the terrain is difficult. At Frampton, New South Wales , Australia, the uphill track follows something of
1080-842: The Bayerische Regiobahn (BRB). The BRB is a sister company of the Bayerische Oberlandbahn (BOB) and belongs to the Veolia Group . The BRB operates the Weilheim–Peißenberg , Schongau–Peißenberg , and Augsburg–Geltendorf–Weilheim lines and, from 2009, has also worked the Augsburg–Aichach–Ingolstadt and Ingolstadt – Eichstätt Stadt routes. Main line (railway) The main line , or mainline in American English , of
1134-681: The Boyne Viaduct , a bridge just north of Drogheda railway station in Ireland ). The bridge over the Murray River between Albury and Wodonga is double-track, but because of insufficient strength in the bridge only one train is allowed on it at a time. The bridge has since been singled as part of the North East Line Standardisation with the old broad gauge track now disconnected but remains in place on
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#17327762513491188-558: The Canadian National main line in the Greater Toronto Area and Southern Ontario are triple track to facilitate high traffic density of freight services, intercity , and suburban passenger trains sharing the same lines. India, through its state-owned Indian Railways, has initiated the construction of a third track between Jhansi and Nagpur via Bhopal (approximately 590 kilometres (370 miles)) for reducing
1242-580: The Geltendorf–Munich-Pasing section having been electrified two years earlier. Nowadays the Ammersee Railway in only of regional importance. Trains run hourly from Augsburg-Oberhausen via Weilheim to Schongau and back. Until the early 1990s there were still long-distance trains (the FD-Züge ) on the line that did not take the 'bypass' via Munich on their way from the north of Germany to Garmisch-Partenkirchen , but went directly from Augsburg along
1296-584: The Hudson and New Haven Lines, both of which are shared between Metro-North and Amtrak in New York and Connecticut. The New Haven Line is quadruple track along its entire length, while the Hudson Line is only quadruple tracked along the shared portion from Riverdale to Croton–Harmon and along the shared track from Grand Central Terminal to Yankees–East 153rd Street . Amtrak 's Northeast Corridor
1350-619: The Main Western Railway between Wallerawang and Tarana , and between Gresham and Newbridge were singled in the 1990s. A new passing loop was opened on part of the closed track at Rydal in the Wallerawang–Tarana section during 2019. A double-track tunnel with restricted clearances is sometimes singled to form a single track tunnel with more generous clearances, such as the Connaught Tunnel in Canada or
1404-450: The signalling systems, especially where the signalling is mechanical (e.g. semaphore signals ). Where the signals and points (UK term) or rail switches (US) are power-operated, it can be worthwhile to provide signals for each line which cater for movement in either direction, so that the double line becomes a pair of single lines. This allows trains to use one track where the other track is out of service due to track maintenance work, or
1458-426: The 1880s, with full duplication completed around 1910. All bridges, tunnels, stations, and earthworks were built for double track. Stations with platforms with 11-foot (3.4 m) centres had to be widened later to 12-foot (3.7 m) centres, except for Gosford . The former Baltimore and Ohio Railroad (B&O) line between Baltimore and Jersey City , now owned by CSX and Conrail Shared Assets Operations ,
1512-491: The Ammersee Railway to Weilheim. One curious aspect was the mode of operation on the non-electrified section from Geltendorf to Weilheim. A diesel engine was hooked up to the train in Geltendorf or Weilheim and the electric locomotive was hauled along with its pantographs lowered. This gap in the electrified network still remains a stumbling block, because all trains on the Ammersee Railway are diesel-hauled, although there
1566-734: The Southern Pacific's Overland Route , and eastbound trains used the Western Pacific's Feather River Route (now called the Central Corridor ). Crossovers were constructed where the lines ran in close proximity to allow reverse movements. This was necessary as while for most of this run the tracks straddle opposite sides of the Humboldt River , at points the two tracks are several miles apart and some destinations and branch lines can only be accessed from one of
1620-551: The Tickhole Tunnel in New South Wales , Australia. In the case of the Tickhole Tunnel a new single-track tunnel was built and the two tracks in the original tunnel were replaced by one track in the centreline of the tunnel. Another case where this was necessary was the Hastings Line in the United Kingdom, where the tunnels were eventually singled to permit the passage of standard British-gauge rolling stock. Before
1674-588: The bridge. Railways that become especially busy in wartime and are duplicated, especially in World War I, may revert to single track when peace returns and the extra capacity is no longer required. The Flanders campaign saw duplication of the Hazebrouck – Ypres line, amongst other works. Severe gradients can make the headway in the uphill direction much worse than the headway in the downhill direction. Between Whittingham and Maitland, New South Wales ,
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1728-528: The broad gauge declined, the lines were converted to bi-directional double track 1,435 mm ( 4 ft 8 + 1 ⁄ 2 in ) gauge lines. Quadruple track consists of four parallel tracks. On a quad-track line, faster trains can overtake slower ones. Quadruple track is mostly used when there are "local" trains that stop often (or slow freight trains), and also faster inter-city or high-speed "express" trains. It can also be used in commuter rail or rapid transit . The layout can vary, often with
1782-535: The choice of which side the driver should sit is less important. For example, the French SNCF Class BB 7200 is designed to use the left-hand track and therefore uses LHD. When the design was modified for use in the Netherlands as NS Class 1600 , the driving cab was not completely redesigned, keeping the driver on the left even though trains use the right-hand track in the Netherlands. Generally,
1836-400: The classic lines of the former German Alsace and Lorraine), Sweden (apart from Malmö and further south), Switzerland, Italy and Portugal for example, the railways use left-hand running, while the roads use right-hand running. However, there are many exceptions: Handedness of traffic can affect locomotive design. For the driver, visibility is usually good from both sides of the driving cab, so
1890-498: The different tracks is called the "six foot". It is not safe to stand in the gap between the tracks when trains pass by on both lines, as happened in the Bere Ferrers accident of 1917. When one track of a double-track railway is out of service for maintenance or a train breaks down, all trains may be concentrated on the one usable track. There may be bi-directional signalling and suitable crossovers to enable trains to move onto
1944-680: The direction of the main line by default. Failure to do so has been a factor in several fatal railway accidents , for example the Buttevant Rail Disaster in Ireland, and the Graniteville train crash in the US. This rail-transport related article is a stub . You can help Misplaced Pages by expanding it . Double-track railway A double-track railway usually involves running one track in each direction, compared to
1998-525: The earliest days of railways in the United States most lines were built as single-track for reasons of cost, and very inefficient timetable working systems were used to prevent head-on collisions on single lines. This improved with the development of the telegraph and the train order system. In any given country, rail traffic generally runs to one side of a double-track line, not always the same side as road traffic. Thus in Belgium, China, France (apart from
2052-588: The first to be constructed. They were built by the Augsburg railway division of the Royal Bavarian State Railways and were completed simultaneously on 30 June 1898. The intervening 18.36 km section from Dießen to Schondorf was finished on 24 December 1898. The line was electrified between Mering and Geltendorf from 7 September 1970 in order to provide a diversionary line for the heavily trafficked trunk route from Augsburg to Munich ,
2106-517: The left/right principle in a country is followed mostly on double track. On steam trains, the steam boiler often obscured some of the view, so the driver was preferably placed nearest to the side of the railway, so that it was easier to see the signals. On single track, when trains meet, the train that does not stop often uses the straight path in the turnout, which can be left or right. Double-track railways, especially older ones, may use each track exclusively in one direction. This arrangement simplifies
2160-490: The length and width of trains is contingent on the minimum railway curve radius of the railway. Increasing the width of track centres of 6 metres (20 ft) or more makes it much easier to mount signals and overhead wiring structures. Very widely spaced centres at major bridges can have military value. It also makes it harder for rogue ships and barges to knock out both bridges in the same accident. Railway lines in desert areas affected by sand dunes are sometimes built with
2214-423: The lines. There is a grade separated crossover of the two lines in the shared track area near Palisade, Nevada , which results in trains following right hand traffic in the eastern half of the shared track area, but left hand traffic in the western half. The Union Pacific Railroad has since acquired both of these lines, and continues to operate them as separate lines using directional running. Amtrak also runs
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2268-539: The local train stations, the express trains can pass through the station at full speed. For example on the Nuremberg-Bamberg railway , which is quadruple track for most of its course, the inner two tracks are used by the S-Bahn Nuremberg whereas the outer tracks are used for regional express and Intercity Express trains. The section in northern Fürth where the line is "only" double track creates
2322-560: The loop with close time tolerances, otherwise they will need to slow or even be brought to a complete stop to allow the oncoming train to pass. They are suited to lines with light to moderate traffic. An example of where passing lanes have been installed in order to improve travel times and increase line capacity is the 160-kilometre (100-mile) section of the Main Southern railway line in Australia between Junee and Albury . This
2376-666: The other track expeditiously (such as the Channel Tunnel ), or there may be some kind of manual safeworking to control trains on what is now a section of single track. See single-line working . Accidents can occur if the temporary safeworking system is not implemented properly, as in: From time to time, railways are asked to transport exceptional loads such as massive electrical transformers that are too tall, too wide or too heavy to operate normally. Special measures must be carefully taken to plan successful and safe operation of out-of-gauge trains . For example, adjacent tracks of
2430-442: The outer tracks use bi-directional running and serve local trains exclusively in one direction. During service disruptions on one of the two outer tracks, trains could also bypass the affected sections on the center track. The Union Pacific Railroad mainline through Nebraska has a 108-mile (174 km) stretch of triple track between North Platte and Gibbon Junction, due to a high traffic density of 150 trains per day. Portions of
2484-727: The partial reinstatement of double track. In New Zealand the Melling Line was singled to the Western Hutt Railway Station in Lower Hutt in 1958 after it became a branch line rather than part of the main Hutt Valley Line . 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 . In New South Wales, Australia,
2538-556: The singling, narrow-bodied stock, specially constructed for the line, had to be used. As part of the Regional Fast Rail project in Victoria, Australia , the rail line between Kyneton and Bendigo was converted from double- to single-track to provide additional clearance through tunnels and under bridges for trains travelling at up to 160 km/h (99 mph). A similar process can be followed on narrow bridges (like
2592-626: The tracks' centres makes a difference in cost and performance of a double-track line. The track centres can be as closely spaced and as cheap as possible, but maintenance must be done on the side. Signals for bi-directional working cannot be mounted between the tracks, so they must be mounted on the 'wrong' side of the line or on expensive signal bridges . For standard gauge tracks the distance may be 4 metres (13 ft) or less. Track centres are usually further apart on high speed lines, as pressure waves knock each other as high-speed trains pass. Track centres are also usually further apart on sharp curves, and
2646-400: The traffic load and delays in passenger train arrivals. The construction between Bina and Bhopal and between Itarsi and Budhni had been completed by April 2020. The Melbourne to Albury railway originally consisted of separate 1,600 mm ( 5 ft 3 in ) gauge and 1,435 mm ( 4 ft 8 + 1 ⁄ 2 in ) gauge single track lines, but when traffic on
2700-419: The two outer tracks carrying the local trains that stop at every station so one side of stations can be reached without staircase; this can also be reversed, with express trains on the outside and locals on the inside, for example if staffed ticket booths are wanted, allowing one person for both directions. At other places two tracks on one half of the railway carry local trains and the other half faster trains. At
2754-489: The two tracks are at different levels, with the original southbound and downhill track following ground level with a steep gradient, while the newer northbound and uphill track has a gentler gradient at the cost of more cut and fill . At the Bethungra Spiral , Australia, the downhill track follows the original short and steep alignment, while the uphill track follows a longer, more easily graded alignment including
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#17327762513492808-404: The two tracks separated, so that if one is covered by sand, the other(s) are still serviceable. If the standard track centre is changed, it can take a very long time for most or all tracks to be brought into line. On British lines, the space between the two running rails of a single railway track is called the "four foot" (owing to it being 'four foot something' in width), while the space between
2862-410: Was built as a single track line in stages between 1878 and 1881, and was partially duplicated between 2005 and 2010 by the construction of four passing lanes each 6 km (4 mi) long. In this instance, this was accomplished by extending pre-existing crossing loops of either 900 metres (3,000 ft) or 1,500 metres (4,900 ft) in length. The process of expanding a single track to double track
2916-474: Was not particularly attractive in the past. This has changed since 14 December 2008 with a new, tauter timetable. The variable interval services have been restricted to the Dießen-Weilheim section. On the rest of the line, as on the through services to Schongau and Augsburg-Oberhausen, a strict hourly service is offered. Since 14 December 2008, running powers on the Ammersee Railway have been awarded to
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