A spiral (sometimes called a spiral loop or just loop) is a technique employed by railways to ascend steep hills.
A railway spiral rises on a steady curve until it has completed a loop, passing over itself as it gains height, allowing the railway to gain vertical elevation in a relatively short horizontal distance. It is an alternative to a zig-zag, and avoids the need for the trains to stop and reverse direction while ascending. If the train is longer than the length of each loop it may be possible to view it looping above itself.
The term "loop" is also often used for a railway that curves sharply and goes back on itself: if the railway crosses itself, then it forms a spiral or helix; otherwise, it forms the much more common horseshoe curve or bend.
List of spirals
- Two spirals between Tacuara and Meseta at Tren a las Nubes section of the Salta–Antofagasta railway part of the General Manuel Belgrano Railway. and on the heritage
- Spiral on the uphill track at Bethrunga on the Main Southern railway line in New South Wales. The downhill track remains on the original steep plain 1 in 40 gradient.
- Spiral on the single track at Cougal on the North Coast railway line, New South Wales.
- Four Spirals on the Rhodope Mountain Line between Septemvri to Dobrinishte railway between Velingrad and Cherna Mesta at , , and .:247
- Spiral just outside Klisura at on the Sofia to Tulovo railway.:110:244
- Spiral just outside Radevtsi at on the Ruse to Dimitrovgrad railway.:110:244
- Spiral and horseshoe bends just outside Raduntsi at on the Ruse to Dimitrovgrad railway.:110:244
- Double spiral at Big Hill at on the approach to Kicking Horse Pass on the Canadian Pacific Railway route.
- There used to be a spiral at Trinity, Newfoundland on the former Newfoundland Railway. at
- There used to be a spiral at Rogers Pass at that was superseded when the Connaught Tunnel (British Columbia) was built.
- Spiral between Qingshiya and Guanyinshan at Baoji–Chengdu Railway. on the
- Six spirals on the Chengdu–Kunming Railway at:
- Spiral at Shangshali at Harbin–Manzhouli Railway. on the
- Spiral at Daheba at  on the Sichuan–Chongqing Railway.
- Three spirals on the Liupanshui–Hongguo Railway at:
- There are four spirals on the Southern Xinjiang Railway at , , and on a by-passed section between Yu'ergou and Hejing that is now freight only. This line was rebuilt on a shorter route in 2014.
- There used to be a spiral at Guanjiao at Qinghai–Tibet Railway, it was replaced by a tunnel in 2014. (see photo). on the
- Spiral between Rijeka-Brajdica and Sušak-Pećine at on the Rijeka–Karlovac railway, part of International corridor V. The spiral is mainly in a 1838 m long tunnel.:215
- Spiral between Asmara and Arbaroba at on Eritrean Railways. This spiral pushes the definition of a spiral as the line crosses itself but then immediately crosses back, and it does this in a tunnel.
- Three spirals on the Col de Tende line between Ventimiglia to Cuneo as it passes through France, a further spiral on this line is in Italy.:155
- Spiral at Moûtiers at between Albertville and Bourg-Saint-Maurice used by TGV.
- Spiral partly in a tunnel at Claveisolles at on the Paray-le-Monial to Lozanne line (between Saint-Nizier-d'Azergues and Poule-les-Écharmeaux).
- Spiral north of L'Hospitalet près l'Andorre at Latour-de-Carol and Ax-les-Thermes.:51 on the line between
- There used to be a spiral in the Sayerce tunnel at Pau–Canfranc railway line between Pau and Zaragoza (Spain) in the Pyrenees. This spiral is now a footpath. on the former
- The proposed spirals between The Gravenne and Montpezat at Transcevenole line between Le Puy-en-Velay and Lalevade-d'Ardèche in the Cévennes were never constructed. on the partly completed
- Spiral, known as the Rendsburg Loop, on the northern approach to the Rendsburg High Bridge, a railway viaduct and transporter bridge crossing the Kiel Canal in Rendsburg, Schleswig-Holstein at .:43:95
- Spiral on the Wutach Valley Railway at . The line was built partly for strategic reasons and had to be built to a reasonable gradient in order to haul heavy military trains over it. The alternative, shorter Singen–Waldshut route was not available for this traffic, since it crossed Swiss territory. The line is now a heritage railway.:58
- There are currently three spirals on the Darjeeling Himalayan Railway:
- There used to be a spiral at Dhulghat at between Khandwa and Hingoli on the metre gauge railway, the spiral was apparently removed when the track was upgraded to broad gauge.:41
- Spirals near Dowgal station at horseshoe curves in the Alborz Mountains on the Trans-Iranian Railway. and extensive
- The St. James's Gate Brewery, Dublin, Ireland formerly had an internal 1 ft 10 in (559 mm) gauge railway with a loop in a tunnel to gain height between buildings.
- Spiral at Bortigiadas on the Sassari-Palau railway on Sardinia.:179
- Spiral near Lanusei on the Mandas–Gairo–Arbatax railway on Sardinia.:190
- Varzo Spiral Tunnel near Iselle di Trasquera on the Swiss Federal Railways just south of the Southern Portal of the Simplon Tunnel.:9
- Spiral near Vernante on the Col de Tende railway from Ventimiglia to Cuneo. There are a further three spirals on this line in French territory.:60:155
- Spiral close to Savona at on the Savona–Altare line.:62:155
- Spiral just north of Salerno at on the Salerno–Mercato San Severino railway.:86:129:164
- Spiral at Ragusa at on the approach to Ragusa from Modica on Sicily.:168
- Spiral between Medaglie d'Oro and Salvator Rosa at Naples Metro. Vanvitelli and Quattro Giornale stations are on the loop itself.:112 on Line 1 of
- Spiral at Casole Bruzio on the Cosenza to San Giovanni in Fiore line (line exists but is not in service).:87
- There were three spirals at San Martino on the former Spoleto–Norcia line. Caprareccia and and near
- Spiral South of Echigo-Nakazato at Tokyo bound Jōetsu Line.:53 on the
- Spiral at Shimizu Tunnel at on the Tokyo-bound Jōetsu Line.:53
- Spiral South of Tsuruga Station at on the Hokuriku Main Line to Shin-Hikida Station.:73
- Spiral at Okoba Station at on the Hisatsu Line. Okoba Station is situated on a zig zag part way around the loop.:131
- Spiral on the Nakamura Line just after its junction with the Yodo Line at .:122
- Spiral on the western approach to the Rainbow Bridge at on New Transit Yurikamome automated transit service in Tokyo.:43:149
There are three spirals on the 1,000 mm (3 ft 3 3⁄8 in) gauge railway line from Kenya to Uganda. This railway has been superseded by the Mombasa–Nairobi Standard Gauge Railway, which has removed the need for spirals by constructing tunnels and bridges.
- Spiral South of Mazeras at near Mombasa.
- Spiral near Makutano station at : .
- Spiral near Equator station at .
- Spiral at Geumdae 2nd Tunnel at Jungang Line. There is one loop on a single track railway. A new double track tunnel is under construction to replace loop tunnel. between Geumgyo station and Chiak station on
- Spiral at Daegang Tunnel at Jungang Line;– one loop, single track. between Danseong station and Jungnyeong station on the
- Spiral at Hambaek 1st Tunnel at Hambaek Line;– one loop, single track. between Hambaek station and Jodong station on the
- Spiral at Solan Tunnel at Yeongdong Line. There is one loop on a single track railway but double track is installed in the middle of the tunnel to enable trains from opposing directions to pass each other. between East Baeksan station and Dogye station on the
- One spiral on the Burma Mines Railway at .
- One spiral close to Shwenyaung at on the Thazi-Taunggyi line.
- Raurimu Spiral at on the North Island Main Trunk. The line is single track and involves two short tunnels around a suitable hill.
- Spiral on the Driving Creek Railway at . This railway also has several reverses or zig-zags.
- There used to be a spiral at Ellis and Burnand Tramway, Ongarue, which closed in 1958 and is now part of the Timber Trail. on the
- Spiral on the Flåm Line between Myrdal and Flåm at .
- Spiral on the Vestfold Line around the town of Tønsberg at .
- Spiral just north of Indyuk at North Caucasus Railway route from Tuapse (Tуапсе) through Gornyy to Belorechensk (Белореченск). on the
- There used to be a spiral at "Devil's Bridge", Kholmsk to Yushno-Sakhalinsk on Sakhalin Island. on the now abandoned line from
- Spiral at Jatare at Šargan Eight Heritage Railway in Western Serbia between from Mokra Gora and Šargan Vitasi.:222 on the
- Spiral at Telgártska slučka at on the Brezno to Gelnica Line. The spiral is constructed of two viaducts and a 1,200m tunnel.
- Spiral near Komga at on the branch line to Mthatha as it descends to the Great Kei River.
- Spiral at Van Reenen's Pass at on the line from Harrismith to Ladysmith.
- Spiral near Toses at on the Ripoll to Latour-de-Carol, France line.:30
- Spiral at La Granja de San Vicente at Palencia to A Coruña line.:18 on the
- Spiral at Demodara railway station at on the line from Bandarawela to Badulla. Demodara railway station is located above the spiral tunnel.
- The Gotthard railway has spirals and horseshoe curves or bends mostly in tunnels on its standard gauge, double track line. The spirals are:
- RhB Albulabahn has four spirals, mainly in tunnels, on its metre gauge single track. The spirals are at:
- Brusio spiral viaduct at on RhB Berninabahn. This is a fine example of an open spiral mainly on the Brusio spiral viaduct on a metre gauge single track railway.:145
- Spiral South of Gletsch at on the former Furka Oberalp Bahn, now Dampfbahn Furka-Bergstrecke Heritage Railway. This is a single track partial rack railway with the catenary equipment removed.
- Spiral East of Grengiols at on the former Furka Oberalp Bahn, now Matterhorn Gotthard Bahn, between Grengiols and Lax.:148
- There used to be a spiral at Circle Hill Kenya to Uganda Railway Line to Kasese. on the Western Uganda Extension of the
- Spiral around Dduallt railway station at on the Ffestiniog Railway in Wales.
- The line at Coombe Junction and Liskeard on the Looe Valley Line and on over Moorswater Viaduct forms a complete spiral, climbing up to join the main line at Liskeard. Not all parts are used by passenger trains. from Moorswater cement terminal, through
- Tehachapi Loop, at Tehachapi, California at on the former Southern Pacific Railroad, now part of Union Pacific Railroad.
- Williams Loop, east of East Quincy, California at on the former Western Pacific Railroad now part of Union Pacific Railroad.
- Hiwassee Loop, also known as the Hook and Eye; 2 miles NNE of Farner, Tennessee at on the former Atlanta, Knoxville and Northern Railway now operated as a heritage railroad by the Tennessee Valley Railroad Museum, which operates excursion trains from Etowah, Tennessee to Copperhill, Tennessee via the loop, as well as trains just to the loop and back from Etowah.
- Georgetown Loop, at Georgetown, Colorado at on the former Colorado Central Railroad. The spiral was completed in 1884, abandoned and dismantled in 1939, rebuilt between 1972 and 1984 and is now owned by History Colorado and operated as the Georgetown Loop Railroad.
- The MAX Red Line, a light rail line in Portland, Oregon, loops over itself at in the vicinity of the Gateway Transit Center.
- In the Loop District of the Alaska Railroad at between mileposts 48 and 51 northeast of Seward, Alaska, there was a spiral and a horseshoe curve both on an extensive range of timber trestles up to 106 feet high. Track relocation in 1951 removed all of this but added a new horseshoe at milepost 48. 
- Abandoned spiral at Riflesight Notch Loop at Rollinsville, Colorado at on the former Denver and Salt Lake Railway route over Rollins Pass. The spiral was bypassed by the Moffat Tunnel built in 1928, and was dismantled in 1935.
- Abandoned spiral called Double Circle, or Double Loop, or The Golden Circle, at Eureka, Utah on the former Tintic branch of the Denver and Rio Grande Western Railroad. It was bypassed in 1940 and the branch removed in 1943. east of
- Abandoned spiral on the Roaring Camp Railroad at . The spiral was completed in 1963. The spiral was bypassed by two switchbacks after a trestle fire in 1976.
- Spiral bridge - road equivalent
- Hairpin turn
- List of spiral tunnels and tunnels on a curved alignment
- List of steepest gradients on adhesion railways
- Zig Zag Railways
- Christian Wolmar (1 May 2014). The Iron Road: The Illustrated History of Railways. Dorling Kindersley Limited. pp. 170–. ISBN 978-0-241-18186-7.
- S. M. Yameen Nachsch (1972). Railway Engineering. Caravan Book House.
- William W. Hay (16 June 1982). Railroad Engineering. John Wiley & Sons. pp. 231–. ISBN 978-0-471-36400-9.
- Jim Harter (2005). World Railways of the Nineteenth Century: A Pictorial History in Victorian Engravings. JHU Press. ISBN 978-0-8018-8089-6.
- John Brian Hollingsworth (1982). Atlas of the world's railways. Bison.
- Axel Borsdorf; Christoph Stadel (12 March 2015). The Andes: A Geographical Portrait. Springer. pp. 273–. ISBN 978-3-319-03530-7.
- Pons, Mónica. "The Train to the Clouds, Salta". Welcome Argentina. Retrieved 13 December 2017.
- The Australian encyclopaedia. Michigan State University Press. 1958.
- "Bethungra Spiral". Heritage Council of New South Wales.
- "Cougal To Border Loop, Railway Spiral and Landscape". New South Wales State Heritage Register. Office of Environment and Heritage. Retrieved 25 November 2017.
- William Alan Bayley (1973). Standard Gauge Railway Across Australia. Austrail Publications. ISBN 978-0-909597-09-2.
- Brendan Fox; et al. (2011). The Thomas Cook Rail Map of Europe (Map) (18th ed.). 1:4000000. Cartography by Mary Spence. Thomas Cook Publishing. ISBN 978-1-84848-356-9.
- Ball, Mike (20 March 2017). European Railway Atlas Regional Series, Romania, Bulgaria and Moldova.
- Ball, Mike (1 May 2016). European Railway Atlas.
- Подробна карта на България (A detailed Map of Bulgaria) (Map). 1:380000. ДатаМап-Европа ООД (DataMap Europe). 2014. ISBN 978-954-519-036-0.
- Jane's World Railways. Sampson Low, Marston; New York: Rand McNally. 1960.
- Graeme Pole (1 January 1995). The Spiral Tunnels and the Big Hill: A Canadian Railway Adventure. Altitude Publishing Canada Limited. ISBN 978-1-55153-907-2.
- Barry D. Stewart (2004). Across the Land --a Canadian Journey of Discovery. Trafford Publishing. pp. 224–. ISBN 978-1-4120-2276-7.
- L.D. Cross (21 July 2014). High Peaks Engineering: Rocky Mountain Marvels. Heritage House Publishing Co. pp. 93–. ISBN 978-1-927527-80-1.
- Les Harding (5 February 2008). The Newfoundland Railway, 1898-1969: A History. McFarland. pp. 86–. ISBN 978-1-4766-0839-6.
- Heritage Foundation of Newfoundland and Labrador (January 2011). "Trinity Train Loop". Retrieved 25 October 2017.
- Heritage Foundation of Newfoundland and Labrador. "Trinity Train Loop Registered Heritage Structure". Retrieved 25 October 2017.
- Art Downs (1 May 1985). Incredible Rogers Pass. Heritage House Publishing Co. pp. 27–. ISBN 978-0-919214-08-8.
- "Qingshiya station". China Railway Map. Retrieved 26 August 2019.
- Quail Map Company (2008). China Railway Atlas (third ed.). Quail Map Company. ISBN 978-1-898319-82-5.
- "Baishiyan station". China Railway Map. Retrieved 26 August 2019.
- "Lewu station". China Railway Map. Retrieved 26 August 2019.
- "Wazu station". China Railway Map. Retrieved 26 August 2019.
- "Tiekou station". China Railway Map. Retrieved 26 August 2019.
- "Ananzhuang station". China Railway Map. Retrieved 26 August 2019.
- "Longgudian station". China Railway Map. Retrieved 26 August 2019.
- "Daheba station". China Railway Map. Retrieved 26 August 2019.
- "Maocaoping station". China Railway Map. Retrieved 26 August 2019.
- "Duchuanzhai station". China Railway Map. Retrieved 26 August 2019.
- "Sanjiazhai station". China Railway Map. Retrieved 26 August 2019.
- Yuan Lei (2014-12-29). "袁蕾, 吐库二线正式开通运营 南疆铁路进入电气化时代 新疆日报" [Yuan Lei, spit library second-tier official opening and operation of the Southern Xinjiang Railway electrification into the Xinjiang Daily Times (Machine generated)] (in Chinese). Retrieved 2016-07-04.
- "Long Tunnels". European Tribune. 12 June 2016. Retrieved 18 November 2020.
- Devereux, Nigel (September 2017). "Costa Rican rail variety". The Railway Magazine. Mortons Media Group Ltd.: 104.
- "Friends of Latin American Railways". Retrieved 13 November 2018.
- Ball, Mike (3 September 2017). European Railway Atlas Regional Series, The Balkans.
- Benjaminse Uitgeverij BV (2013). A Travellers' Railway map of Europe (Map) (3rd ed.). 1:3800000. Cartography by Carto Studio BV. Benjaminse Uitgeverij BV. ISBN 978-90-77899-09-0.
- Ball, Mike (15 July 2016). European Railway Atlas Regional Series, Italy.
- Braun, Michel (April 2017). "The Col de Tende Line: A tortuous route and history". Today's Railways Europe. Sheffield, England: Platform 5 Publishing.
- Michelin Editions des Voyages. Michelin. 10 January 2011. ISBN 978-2-06-715561-9.
- "La Boucle Loop Tunnel". Structurae:International Database and Gallery of Structures. Retrieved 15 December 2017.
- "Moûtiers, très ferroviphile en 2013 !". Actu Montagne. The Serac Editions. Retrieved 15 December 2017.
- Ian Allan Publishing (20 March 2015). Rail Atlas Europe. Ian Allan Publishing. ISBN 978-0-7110-3808-0.
- "Tunnel deVigue" (PDF). Invetaire des tunnels ferroviaires de France. Retrieved 12 August 2019.
- Ball, Mike (15 February 2019). European Railway Atlas Regional Series, Spain & Portugal.
- "Tunnel de Saillens" (PDF). Invetaire des tunnels ferroviaires de France. Retrieved 6 September 2020.
- "Tunnel de Sayerce" (PDF). Invetaire des tunnels ferroviaires de France. Retrieved 24 June 2016.
- C. Harald Harlinghausen; Hartmuth Merleker (1986). Germany Federal Republic. Nagel. ISBN 978-2-8263-0761-7.
- W.J.K.Davies (1965). Railway Holiday in Northern Germany. David and Charles.
- Great Britain. Naval Intelligence Division (1945). Germany: Ports and communications. Naval Intelligence Division.
- Terry Martin (2006). The Iron Sherpa: The Story of the Darjeeling Himalayan Railway, 1879-2006. The Iron Sherpa by T. Martin. ISBN 978-1-900622-10-3.
- Going Loopy. Darjeeling Himalayan Railway Society. 2005. ISBN 0-9541602-2-3.
- UNESCO World Heritage. "Mountain Railways of India". Retrieved 7 November 2017.
- The Great Indian Railway Atlas. Samit Roychoudhury. 2005. ISBN 81-901457-0-3.
- Hugh Hughes (1981). Middle East railways. Continental Railway Circle.
- Ellison, Paul (December 1968). "Guinness Brewery Tramways". The Industrial Railway Record. The Industrial Railway Society. pp. 337–347. Retrieved 8 December 2017.
- Atlante Stradale Italia (Road Atlas). Instituto Geografico DeAgostini. 2009. ISBN 9788851114398.
- John Organ (November 2013). Sardinia and Sicily Narrow Gauge. Middleton Press. ISBN 978-1-908174-50-5.
- "THE SIMPLON TUNNEL". The Capricornian. Rockhampton, Qld: National Library of Australia. 15 October 1904. p. 21. Retrieved 19 March 2013.
- P. M. Kalla-Bishop (1967). Railway Holiday in Italy. David & Charles.
- P. M. Kalla-Bishop (1970). Mediterranean island railways. A. M. Kelley. p. 47.
- Ovenden, Mark (2007). Transit maps of the world. London: Penguin Books. ISBN 978-0-14-311265-5.
- "Map of Naples Metro 2017" (PDF). Azienda Napoletana Mobilità (ANM). Retrieved 21 January 2018.
- "The route of the former railway Spoleto-Norcia". Bella Umbria. Retrieved 16 December 2017.
- A History of Japanese Railways, 1872-1999. East Japan Railway Culture Foundation. 2000. ISBN 978-4-87513-089-5.
- Shobunsha (2012). All-Japan Road Atlas. ISBN 978-4-398-60034-9.
- National Defense Transportation Journal. National Defense Transportation Association. 1953.
- "Kenya opens Nairobi-Mombasa Madaraka Express railway". BBC News. 31 May 2017. Retrieved 22 December 2017.
- Ruthi, William (8 May 2017). "Last ride on the Lunatic Express". Daily Nation.
- "End of the line for 'Lunatic Express?' Kenya begins multi-billion dollar railway". CNN News. Retrieved 22 December 2017.
- "Kenya's new Madaraka Express railway in pictures". BBC. BBC. Retrieved 22 December 2017.
- Quail Map Company (1996). Korea, North and South Railway Map (Map). Quail Map Company. ISBN 978-1-898319-21-4.
- "Design/Construction Package Yeongdong Line Relocation (Dongbaeksan - Dogye)". Sambo Engineering. Archived from the original on 22 July 2011. Retrieved 7 September 2020.
- "Detailed design of Yeongdong Line for railway moving establishment construction work between Dongbaeksan and Dogye". Chunsuk Engineering. Archived from the original on 22 July 2011. Retrieved 7 September 2020.
- "Voyages train voyageur (in French)". Madarail. Retrieved 16 December 2017.
- "Route map". Chepe-Ferrocarril Barrancas del Cobre. Retrieved 13 December 2017.
- Joseph Wampler (1969). New Rails to Old Towns: The Region and Story of the Ferrocarriles Chihuahua Al Pacífico. The Author.
- Lonely Planet (1 August 2014). Great Journeys: Travel the World's Most Spectacular Routes. Lonely Planet Publications. ISBN 978-1-74360-593-6.
- "On Burma Corporation Ltd". Australasian Institute of Mining and Metallurgy. Australasian Institute of Mining Engineers: 91. 1922. Retrieved 23 December 2017.
- "Railway Gazette International". Railway Gazette International. Reed Business Pub. 66. 1937. Retrieved 23 December 2017.
- Dickinson, Rob. "The Burma Mines Railway 1999". The International Steam Pages. Retrieved 8 December 2017.
- Colin Metcalfe Enriquez (1935). Beautiful Burma. Myanmahita Magazine.
- Bill Pierre (1 January 1981). North Island Main Trunk: An Illustrated History. A.H. & A.W. Reed. ISBN 978-0-589-01316-5.
- Nock O.S. (1978). World Atlas of Railways. ISBN 0-86134-003-5.
- Lang, Sarah (7 June 2009). "Coromandel: Water world". The New Zealand Herald. Retrieved 13 December 2017.
- Mahoney, Paul (24 Sep 2007). "Bush trams and other log transport - Curves, trestles and inclines". Te Ara - the Encyclopedia of New Zealand. Retrieved 13 December 2017.
- Sigurd H. Unneberg, Sem og Slagen, en bygdebok Bind 2, Kulturhistorie, del 2 . Tønsberg: Høgskolen i Vestfold, 2001. Relevant chapter is online here Archived 2016-03-03 at the Wayback Machine (in Norwegian)
- Popov, Yuri. "Severo-Kavkazskaya Railroad, 06-05 Sochi". Railroad Maps. University of Michigan. Retrieved 23 November 2020.
- "Большой петлевой тоннель [Large loop tunnel]". BAMTONNELSTROY (in Russian). Archived from the original on 21 November 2019. Retrieved 7 September 2020.
- South Africa; South Africa. Railways and Harbours Board (1947). Their Majesties the King and Queen and Their Royal Highnesses the Princess Elizabeth and the Princess Margaret in the Union of South Africa: February-April 1947. South African Railways.
- Guide to Southern Africa. S. Low, Marston & Company. 1971.
- "Kei Rail revival will support regional development". Railway Gazette International. 1 July 2008. Retrieved 23 December 2017.
- Openbare Werke, Anleg, en Vervoer. Thomson Publications. 1959.
- "NATAL-ORANGE FREE STATE railway link". The Railway Gazette. 115: 343. July 1961.
- John R. Shorten; Johannesburg (South Africa). City Council (1970). The Johannesburg saga. John R. Shorten (Proprietary) ltd.
- Collins Road Atlas: Spain and Portugal (Road Atlas). Collins. 2002. ISBN 0007140738.
- "159-II" (Map). Torre del Bierzo (2nd ed.). 1:25000. Mapa Topografico Nacional de Espana. 2002.
- P. N. Cumaranatunga (2009). Patriots of Lanka. P.N. Cumaranatunga. ISBN 978-955-658-116-4.
- Ratnasinghe, Aryadasa. "Train to Badulla". The Sunday Times - Sri Lanka. Retrieved 13 December 2017.
- Ball, Mike (15 July 2016). European Railway Atlas Regional Series, Switzerland.
- John Westwood (2009). The Historical Atlas of World Railways. Cartographica Press. ISBN 978-1-84573-428-2.
- Anthony J. Lambert (2005). Switzerland: Rail, Road, Lake. Bradt Travel Guides. ISBN 978-1-84162-132-6.
- Quail Map Company (1 January 1993). China Railway Atlas (first ed.). Quail Map Company. ISBN 978-0-900609-94-7.
- The Taiwan Railway 1966-1970. Loren Aandahl. 2011. ISBN 978-0-615-39162-5.
- Mohamed Amin; Alastair Matheson; Duncan Willetts (1986). Railway across the Equator: the story of the East African line. Bodley Head. ISBN 978-0-370-30774-9.
- G. T. Heavyside (1980). Narrow Gauge Into the Eighties. David and Charles. ISBN 978-0-7153-7979-0.
- S. K. Baker (2010). Rail Atlas Great Britain and Ireland. Oxford Publishing Company. ISBN 978-0-86093-632-9.
- Ian Allan Publishing (1982). Pre-Grouping Railway Junction Diagrams 1914. Ian Allan Publishing. ISBN 978-0-7110-1256-1.
- P. R. Griswold (1992). Railroads of California: Seeing the State by Rail. American Traveler Press. ISBN 978-1-55838-121-6.
- J. David Ingles (2001). Guide to North American Railroad Hot Spots. Kalmbach Publishing, Co. ISBN 978-0-89024-373-2.
- Brian Solomon (2003). Burlington Northern Santa Fe Railway. Voyageur Press. ISBN 978-1-61060-361-4.
- Maury Klein (1972). History of the Louisville & Nashville Railroad. University Press of Kentucky. ISBN 0-8131-2915-X.
- Phelps R. Griswold; Bob Griswold (1988). Railroads of Colorado: A Guide to Modern and Narrow Gauge Trains. American Traveler Press. ISBN 978-1-55838-088-2.
- John William Howard (October 26, 2017). "TriMet considering expansion of MAX Red Line to county fairgrounds". Portland Tribune. Retrieved 2018-01-15.
- Prince, B.D.The Alaska Railroad in Pictures 1914-1964; Ken Wray's Print Shop, Anchorage, 1964
- R. A. LeMassena (June 1984). Colorado's mountain railroads. Smoking Stack Press.
- "D&RGW Tintic Branch History". Retrieved 2016-09-13.
- "Railroads and Mining at Tintic". Retrieved 2016-09-13.
- "Eureka Ghost Rail: Tintic Range Railroad". Retrieved 2016-09-13.
- Beniam Kifle; Nathan Goodman (2013). Roaring Camp Railroads. Arcadia Publishing. ISBN 978-1-4671-2996-1.
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