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21-755: The Smørstein Tunnel runs through the hill of Smørstein in Holmestrand, Norway. The 288-meter (945 ft) tunnel is single track and electrified at 15 kV  16.7 Hz AC . The tunnel is located next to County Road 313 . It constitutes part of the Vestfold Line, owned by the Norwegian National Rail Administration . The northern entrance of the tunnel is located at a milestone distance of 81.97 kilometers (50.93 mi) from Oslo , 1.86 kilometers (1.16 mi) from

42-413: 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

63-459: 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

84-553: 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. Holmestrandsporten The Holmestrandsporten Tunnel ( Holmestrandsporten )

105-564: A month, nearly 30,000 cubic meters (1,100,000 cu ft) of earth had slid into the fjord. It was at the time the most extensive landslide to hit one of NSB's lines. The slide caused problems for NSB to conduct operations on the line. At first the passengers walked past the site along an old animal path and onwards along an old carriage path. The shipping company Westergaard & Co was hired and they operated Færder , capable of 200 passengers, which ran between Framnæs and Bogen. Elderly and sick passengers were recommended to instead travel via

126-401: A realignment of a road. The earthwork from the construction was piled up close to the fjord. Its weight caused a landslide on 17 August, in which the masses slid into the fjord. This caused a series of successive smaller slides, each wave originating closer and closer to the railway tracks. All available maintenance of way crew were prescribed from the district. NSB originally operated trains past

147-624: 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

168-541: 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

189-488: A tunnel, as the ground was considered too unstable to support railways. The Smørstein Tunnel opened on 25 May 1921, and was at the time the only tunnel on the Vestfold Line between Drammen and Larvik . The tunnel was electrified on 1 December 1957. It remained the only tunnel on the line north of Larvik until 2010, when the Jarlsberg Tunnel opened. The National Rail Administration is in the process of upgrading

210-580: Is a 12,300-meter (7.6 mi) long double track railway tunnel which runs through Holmestrandfjellet in Holmestrand and Tønsberg in Vestfold , Norway . It was opened for traffic on Monday 28 November 2016. Located on the Vestfold Line , the tunnel was built as part of the 14.3-kilometer (8.9 mi) double-track high-speed segment from Holm to Nykirke . The new Holmestrand Station

231-421: 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

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252-466: The Moss–Horten Ferry . The run was later moved to Holmestrand , a distance of 4.7 kilometers (2.9 mi). Later the ferry SS Bastø 1 was hired, allowing an entire train load to be carried in one sailing. Four hundred men, of which one hundred were soldiers, were brought in to rebuild the line. A summer home, Trollstua, was rented and used as head offices. A temporary station was erected north of

273-402: The Vestfold Line on the section past Smørstein and the line and tunnel will be closed. Single track (rail) 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

294-399: The Vestfold Line to double track and high speed , which is scheduled to eventually see the replacement of all single-track sections of the line. Construction of the 14.1-kilometer (8.8 mi) Holm–Nykirke section, which is dominated by the 12.3-kilometer (7.6 mi) Holmestrandsporten tunnel, started on 16 August 2010 and is scheduled for completion in 2015. The new segment will replace

315-501: The closed station of Smørstein, which was in use from 1921 to 1978. The original railway line past Smørstein opened on 13 October 1881, following a route which ran closer to the fjord. During construction in 1880 the area had experienced a landslide which had nearly taken with it the permanent way . In August 1918 the Norwegian State Railways (NSB) was working on building a level crossing at Smørstein as part of

336-485: 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

357-503: The section, but eventually chose to evacuate the trains while they ran past the site. By the afternoon of the 18 August 4,000 cubic meters (140,000 cu ft) of earthwork had slid out. The slide area was 50 meters (160 ft) wide and larger and larger cracks were forming in the road. Small slides occurred at roughly fifteen-minute intervals. In the evening the head engineer on the site stopped all train traffic and operations were changed so there were trains operating at both sides of

378-409: The slide and temporary canteens and material sheds were built for the crew. Work ran through the evening. The geological surveys were led by Professor Brøgger, who concluded that the slide was caused by faults in the fjord. At first the work focused on constructing a new temporary line past the site. This allowed trains to pass the site from 28 October. Construction then continued with the building of

399-434: The slide. The smaller slides continued and in the morning of 19 August the land under the tracks had slid away, leaving the rails hanging in mid-air over a distance of 70 meters (230 ft). The guard house was evacuated and it was taken by the slide the following day. In all 12,000 to 15,000 cubic meters (420,000 to 530,000 cu ft) of earthwork had been carried away by then. When the slides finally had concluded after

420-594: 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

441-424: 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

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