Zig zag (railway)

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Australia: the Lithgow Zig Zag Zig zag railway at Lithgow.jpg
Australia: the Lithgow Zig Zag
Germany: zig zag required to cross the outer dyke on the railway serving the island of Nordstrandischmoor Lorenbahn Nordstrandischmoor25.jpg
Germany: zig zag required to cross the outer dyke on the railway serving the island of Nordstrandischmoor
India: the Darjeeling Himalayan Railway, a UNESCO World Heritage Site, with six full zig zags DHR Route Map.jpg
India: the Darjeeling Himalayan Railway, a UNESCO World Heritage Site, with six full zig zags
Italy: zig zag on the Cecina-Volterra railway Panoramica regresso Saline-Volterra.jpg
Italy: zig zag on the Cecina-Volterra railway
Japan: Obasute Station platform sign displaying the switchback Obasute Station Sign.jpg
Japan: Obasute Station platform sign displaying the switchback
North Korea: switchback between Tanballyong and Malhwiri Kumgangsan line switchback.png
North Korea: switchback between Tanballyŏng and Malhwiri
Switzerland: SBB A 3/5 on the turntable at Chambrelien railway station SBB A 3-5 617 in Chambrelien.JPG
Switzerland: SBB A 3/5 on the turntable at Chambrelien railway station

A railway zig zag or switchback is a railway operation in which a train is required to switch its direction of travel in order to continue its journey. While this may be required purely from an operations standpoint, it is also ideal for climbing steep gradients with minimal need for tunnels and heavy earthworks. [1] For a short distance (corresponding to the middle leg of the letter "Z"), the direction of travel is reversed, before the original direction is resumed. [2] Some switchbacks do not come in pairs, and the train may then need to travel backwards for a considerable distance.

Contents

A location on railways constructed by using a zig-zag alignment at which trains must reverse direction to continue is a reversing station. [3]

One of the best examples is the Darjeeling Himalayan Railway, a UNESCO World Heritage Site railway in India, which has six full zig zags and three spirals. [4]

Advantages

Zig zags tend to be cheaper to construct because the grades required are discontinuous. Civil engineers can generally find a series of shorter segments going back and forth up the side of a hill more easily and with less grading than they can a continuous grade, which must contend with the larger scale geography of the hills to be surmounted.

Disadvantages

Zig zags suffer from a number of limitations:

Hazards

If the wagons in a freight train are marshaled poorly, with a light vehicle located between heavier ones (particularly with buffer couplings), the move on the middle road of a zig zag can cause derailment of the light wagon. [7]

Examples

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<span class="mw-page-title-main">Spiral (railway)</span> Railway layout for steep climbs

A spiral is a technique employed by railways to ascend steep hills.

<span class="mw-page-title-main">Zig Zag Railway</span> Railway line in New South Wales, Australia

The Zig Zag Railway is an Australian heritage railway, situated near Lithgow, New South Wales. It was opened by the not-for-profit Zig Zag Railway Co-op as an unpaid volunteer-staffed heritage railway in October 1975, using the alignment of the Lithgow Zig Zag line that formed part of the Main Western line between 1869 and 1910. The line climbs the western flank of the Blue Mountains, using railway zig zags to gain height.

Hillclimbing is a problem faced by railway systems when a load must be carried up an incline. While railways have a great ability to haul very heavy loads, this advantage is only significant when the tracks are fairly level. As soon as the gradients increase, the tonnage that can be hauled is greatly diminished.

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<span class="mw-page-title-main">Lapstone, New South Wales</span> Town in New South Wales, Australia

Lapstone is a township on the eastern escarpment of the Blue Mountains in New South Wales, Australia. Elevation 160 m (525 ft). Lapstone is located 62 kilometres west of the Sydney CBD in the local government area of the City of Blue Mountains and is part of the federal electorate of Macquarie. Lapstone consists mostly of stand-alone housing and has a few public facilities. At the 2016 census, Lapstone had a population of 961 people. Lapstone was originally bought and developed by Mr Arthur J Hand, an Alderman of the Blue Mountains City Council.

<span class="mw-page-title-main">Lapstone Zig Zag</span> Bridge in New South Wales, Australia

The Lapstone Zig Zag was a zig zag railway built between Emu Plains and Blaxland stations on the Main Western Line of New South Wales in Australia. Constructed between 1863 and 1865 to overcome an otherwise insurmountable climb up the eastern side of the Blue Mountains, the zig zag and associated Knapsack Viaduct, a sandstone arch viaduct, were designed by John Whitton, Engineer-in-Charge of New South Wales Government Railways, and were built by William Watkins. The zig zag was listed on the Blue Mountains local government heritage register on 27 December 1991; while the adjacent Knapsack Viaduct was listed on the New South Wales Heritage Database on 2 April 1999. The Lapstone Zig Zag was the world-first Zig Zag constructed on any main-line railway.

<span class="mw-page-title-main">Blue Mountains Line</span> Rail service in New South Wales, Australia

The Blue Mountains Line (BMT) is an inter urban commuter rail service operated by NSW TrainLink serving the Blue Mountains region of New South Wales, Australia. The line travels west from Sydney to the major town of Katoomba and on to Mount Victoria, Lithgow and Bathurst. Mount Victoria is the terminus for most electric services, but some services terminate at Lithgow instead. Two express services per day in each direction, known as the Bathurst Bullet, extend to the regional city of Bathurst, which is supplemented by road coaches connecting Bathurst to Lithgow. Due to electrification limits at Lithgow, the Bathurst Bullet is run using the Endeavour railcars, which operate on diesel. The Blue Mountains Line operates over a mostly duplicated section of the Main Western line. As such, the tracks are also traversed by the Central West XPT, Outback Xplorer and Indian Pacific passenger services and by freight trains.

<span class="mw-page-title-main">Zig Zag railway station</span> Railway station in New South Wales, Australia

Zig Zag railway station is located on the New South Wales Main Western Line. It was originally built in April 1878 and closed in 1910 due to the opening of the Ten Tunnels Deviation which bypassed the original site of the station. The station was not rebuilt until 1959 when a new station was built alongside the 1910 alignment in a similar location to the 1878 station.

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The Main Western Railway is a major railway in New South Wales, Australia. It runs through the Blue Mountains, and Central West regions. It is 825 kilometres (513 mi) with 484 kilometres (301 mi) operational & 341 kilometres (212 mi) under construction & repairs.

<span class="mw-page-title-main">Lithgow Zig Zag</span> Railway line in New South Wales, Australia

The Lithgow Zig Zag is a heritage-listed former zig zag railway line built near Lithgow on the Great Western Line of New South Wales in Australia. The zig zag line operated between 1869 and 1910, to overcome an otherwise insurmountable climb and descent on the western side of the Blue Mountains. It was designed by John Whitton and built from 1863 to 1869 by Patrick Higgins as contractor. It is also known as the Great Zig Zag Railway and Reserves and Zig Zag Railway. The property is owned by Department of Planning and Infrastructure. It was added to the New South Wales State Heritage Register on 2 April 1999.

<span class="mw-page-title-main">Ten Tunnels Deviation</span> Heritage listed railway tunnels in New South Wales, Australia

The Ten Tunnels Deviation is a heritage-listed 9.2-kilometre (5.7 mi) section of the Main Western Line between Newnes Junction and Zig Zag stations in Lithgow, New South Wales, Australia. It was designed and built by the New South Wales Government Railways and built from 1 June 1908 and 16 October 1910. It is also known as Great Zig Zag Railway deviation tunnels and Bell to Zig Zag Ten Tunnel Railway Deviation. It was added to the New South Wales State Heritage Register on 2 April 1999.

The Glenbrook deviation was a section of track on the Main Western line from the first Knapsack Viaduct to old Glenbrook station in the Blue Mountains of New South Wales, Australia. The approximately five-mile-long (eight-kilometre) deviation was constructed from 1891 to 1892 and replaced the Lapstone Zig Zag. The deviation was closed in 1913 when it was replaced by the second Glenbrook deviation and the second Glenbrook Tunnel, that continues to carry the Main Western line today.

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<span class="mw-page-title-main">Bottom Points railway station</span> Railway station in New South Wales, Australia

Bottom Points is a railway station on the Zig Zag Railway in the Blue Mountains area of New South Wales.

<span class="mw-page-title-main">Glenbrook Tunnel (1892)</span>

The Glenbrook Tunnel is a heritage-listed single-track former railway tunnel and mustard gas storage facility and previously a mushroom farm located on the former Main Western Line at the Great Western Highway, Glenbrook, in the City of Blue Mountains local government area of New South Wales, Australia. The Department of Railways designed the tunnel and built it from 1891 to 1892. It is also known as Lapstone Hill tunnel and Former Glenbrook Railway and World War II Mustard Gas Storage Tunnel. The property is owned by Blue Mountains City Council and Land and Property Management Authority, an agency of the Government of New South Wales. It was added to the New South Wales State Heritage Register on 5 August 2011. The railway tunnel was originally part of the Glenbrook 1892 single-track deviation, which bypassed the Lapstone Zig Zag across the Blue Mountains. It is 634 metres; 693 yards long and is constructed in an 'S' shape with a gradient of 1:33.

The Glenbrook deviation is a section of track on the Main Western line from Emu Plains to Blaxland stations in the Blue Mountains of New South Wales, Australia. The approximately seven-mile-long (eleven-kilometre) double-track deviation was constructed from 1911 to 1913 and replaced the single-track first Glenbrook deviation and the first Glenbrook Tunnel.

References

  1. Raymond, William G. (1912). "Railway Engineering" (Google books). In Beach, Frederick Converse (ed.). The Americana: A Universal Reference Library, Comprising the Arts and Sciences, Literature, History, Biography, Geography, Commerce, Etc., of the World. Vol. 17. New York: Scientific American Compiling Department. Retrieved 3 January 2010. High mountain levels … may be tunneled … but … may be reached by one of several methods adopted to secure practical grades: (1) Zig-zag development … (2) Switchback development … (3) Spirals or loops …
  2. Raymond 1912. "Switch-back development … necessitating the use of switches at these ends and the backing of the train up alternate stretches."
  3. Jackson, Alan A. (2006). The Railway Dictionary (4th ed.). Stroud: Sutton Publishing. p. 285. ISBN   0-7509-4218-5.
  4. "Mountain Railways of India". UNESCO World Heritage Centre. Retrieved 30 April 2006.
  5. "The Zig-Zag Deviation". The Dubbo Liberal and Macquarie Advocate (NSW : 1892–1927) . NSW: National Library of Australia. 5 December 1908. p. 4. Retrieved 17 February 2013.
  6. 1 2 Vielbaum, Walt; Hoffman, Philip; Ute, Grant; Townley, Robert (2005). San Francisco's Market Street Railway. Arcadia Publishing. pp. 86–87. ISBN   9780738529677.
  7. "The Railway Accident on the Zig-zag". Bathurst Free Press and Mining Journal (NSW : 1851–1904) . NSW: National Library of Australia. 10 April 1895. p. 3. Retrieved 19 February 2013.
  8. "Historical and Archaeological Assessment of Proposed Cycleway, Near Thornleigh Quarry, Via De Saxe Close, Thornleigh (Berowra Valley Regional Park), N.S.W." (PDF). The construction of the railway siding and zig-zag to the quarry and also Hall’s Camp were associated with Amos & Co, who won the contract to build the section of railway from Strathfield to Hawkesbury River. Edward Higginbotham & Associates PTY LTD. March 2002. Retrieved 19 November 2017.
  9. "Bang rdsskisser SVJ/HFJ". www.ekeving.se.
  10. "Bandel 660". www.historiskt.nu. Retrieved 19 November 2020.
  11. Callwell, Robert (September 1999). "Transit in San Francisco: A Selected Chronology, 1850–1995" (PDF). San Francisco Municipal Railway. p. 90.