View source for Railway track

{{Short description|Rail infrastructure}}
{{Redirect2|Railroad track|Rail track|the song|Railroad Track (song)|the defunct British company|Railtrack}}
{{Redirect|Permanent way}}
{{Use British English|date=January 2025}}
{{Use dmy dates|date=March 2014}}
[[File:Australian National Railways track with concrete sleepers.jpg|thumb|350px|alt=Photo of straight railway track with shiny rails and well-formed ballast laid level with the tops of the concrete sleepers or crossties|Common contemporary practice in track construction, featuring well-drained ballast spread level with the tops of concrete sleepers/crossties – Australian National Railways, ca 1982]]
{{Train topics}}

'''Railway track''' ({{abbr|CwthE|Commonwealth English}} and [[International Union of Railways|UIC terminology]]) or '''railroad track''' ({{abbr|NAmE|North American English}}), also known as '''permanent way (per way)''' ({{abbr|CwthE|Commonwealth English}})<ref>{{cite book|title=The Australian National Dictionary |publisher=Oxford University Press |page=473 |editor=W. S. Ramson |year=1988 |isbn=0195547365}}</ref> or "'''P way'''" ({{abbr|BrE|British English}}<ref>{{cite book|title=Ellis' British Railway Engineering Encyclopaedia |publisher=lulu.com |page=291 |editor=Iain Ellis |year=2010 |isbn=978-1-4461-8190-4}}</ref> and [[English in the Commonwealth of Nations#Indian subcontinent|Indian English]]), is the structure on a [[Rail transport|railway or railroad]] consisting of the [[Rail profile|rails]], [[Rail fastening system|fasteners]], sleepers ([[railroad tie]]s in American English) and [[Track ballast|ballast]] (or [[Ballastless track|slab track]]), plus the underlying [[subgrade]]. It enables [[train]]s to move by providing a dependable, low-friction surface on which steel wheels can roll. Early tracks were constructed with wooden or cast-iron rails, and wooden or stone sleepers. Since the 1870s, rails have almost universally been made from steel.

==Historical development==
{{main|History of the railway track}}
{{Further|Wagonway|Plateway}}

The first railway in Britain was the [[Wollaton Wagonway]], built in 1603 between Wollaton and Strelley in Nottinghamshire. It used wooden rails and was the first of about 50 wooden-railed [[Tramway (industrial)|tramways]] built over the subsequent 164 years.<ref name=Dow/> These early wooden tramways typically used rails of oak or beech, attached to wooden sleepers with iron or wooden nails. Gravel or small stones were packed around the sleepers to hold them in place and provide a walkway for the people or horses that moved wagons along the track. The rails were usually about {{convert|3|ft|m}} long and were not joined - instead, adjacent rails were laid on a common sleeper. The straight rails could be angled at these joints to form primitive curved track.<ref name=Dow/>

The first iron rails laid in Britain were at the Darby Ironworks in [[Coalbrookdale]] in 1767.<ref>{{cite web |url=https://www.quakersintheworld.org/quakers-in-action/286/Railways-in-Britain |work=Quakers in the World |title=Railways in Britain}}</ref>

When [[steam locomotive]]s were introduced, starting in 1804, the track then in use proved too weak to carry the additional weight. [[Richard Trevithick]]'s pioneering locomotive at [[Richard Trevithick#"Pen-y-Darren" locomotive|Pen-y-darren]] broke the [[plateway]] track and had to be withdrawn. As locomotives became more widespread in the 1810s and 1820s, engineers built rigid track formations, with iron rails mounted on stone sleepers, and cast-iron chairs holding them in place. This proved to be a mistake, and was soon replaced with flexible track structures that allowed a degree of elastic movement as trains passed over them.<ref name=Dow/>

==Structure==
[[File:Section through railway track and foundation.png|upright=1.3|thumb|<small>Section through railway track and foundation showing the ballast and formation layers. The layers are slightly sloped to help drainage. <br> Sometimes there is a layer of rubber matting (not shown) to improve drainage, and to dampen sound and vibration</small>]]

===Traditional track structure===
{{original research section|date=August 2022}}
Traditionally, tracks are constructed using flat-bottomed steel rails laid on and spiked or screwed into timber or pre-stressed concrete sleepers (known as ties in North America), with crushed stone [[Track ballast|ballast]] placed beneath and around the sleepers.<ref>{{Cite web |last=Connor |first=Piers |date=May 10, 2017 |title=Track Basics |url=http://www.railway-technical.com/archive/track-basics-v2.pdf |access-date=September 2, 2022 |website=Railway Technical Website}}</ref><ref>{{Cite book |last=Departments of the Army and the Air Force |url=https://armypubs.army.mil/epubs/DR_pubs/DR_a/pdf/web/tm5_628.pdf |title=Railroad Track Standards |date=April 8, 1991 |location=Washington, D.C. |pages=3-1–7-4}}</ref>

Most modern railroads with heavy traffic use continuously welded rails that are attached to the sleepers with base plates that spread the load. When concrete sleepers are used, a plastic or rubber pad is usually placed between the rail and the tie plate. Rail is usually attached to the sleeper with resilient fastenings, although [[cut spike]]s are widely used in North America. For much of the 20th century, rail track used softwood timber sleepers and jointed rails, and a considerable amount of this track remains on secondary and tertiary routes.

In North America and Australia, [[Rail profile#Flat bottomed rail|flat-bottomed rails]] were typically fastened to the sleepers with dog spikes through a flat tie plate. In Britain and Ireland, [[Rail profile#Bullhead rail|bullhead rails]] were carried in cast-iron chairs which were spiked to the sleepers. In 1936, the [[London, Midland and Scottish Railway]] pioneered the conversion to flat-bottomed rail in Britain, though earlier lines had made some use of it.<ref name=Dow>{{cite book |title=The Railway: British Track Since 1804 |first=Andrew |last=Dow |publisher=Pen & Sword Transport |location=Barnsley |date=30 October 2014 |isbn=9781473822573}}</ref>

Jointed rails were used at first because contemporary technology did not offer any alternative. However, the intrinsic weakness in resisting vertical loading results in the ballast becoming depressed and a heavy maintenance workload is imposed to prevent unacceptable geometrical defects at the joints. The joints also needed to be lubricated, and wear at the fishplate (joint bar) mating surfaces needed to be rectified by shimming. For this reason jointed track is not financially appropriate for heavily operated railroads.

Timber sleepers are of many available timbers, and are often treated with [[creosote]], [[chromated copper arsenate]], or other wood preservatives. Pre-stressed concrete sleepers are often used where timber is scarce and where tonnage or speeds are high. Steel is used in some applications.

[[Track ballast]] is usually stone crushed to particular specifications. Its purpose is to support the sleepers and allow some adjustment of their position while allowing free drainage.

<gallery class="center centered" style="line-height:120%&quot;" widths="220" heights="160" mode="packed">
 File:Close-up of railway track.jpg|Traditional railway track showing ballast, sleepers, and rail fixings

 File:Track of Singapore LRT.jpg|Guideway of the [[Singapore LRT|Light Rail Transit system]], [[Singapore]], on which rubber-tyred automated people-mover vehicles operate
<!-- File:|thumb|<br/><small>()</small> &shy; -->
</gallery>

===Ballastless track===
{{main|Ballastless track}}
[[File:Feste Fahrbahn FFBögl.jpg|thumb|Slab track with flexible noise-reducing rail fixings, built by German company [[Max Bögl]], on the Nürnberg–Ingolstadt [[Intercity-Express|high-speed]] line]]

A disadvantage of traditional track structures is the heavy demand for maintenance, particularly surfacing (tamping) and lining to restore the desired [[track geometry]] and smoothness of vehicle running. Weakness of the subgrade and drainage deficiencies also lead to heavy maintenance costs. This can be overcome by using ballastless track. In its simplest form this consists of a continuous slab of concrete (like a highway structure) with the rails supported directly on its upper surface (using a resilient pad).

There are a number of proprietary systems; variations include a continuous reinforced concrete slab and the use of pre-cast pre-stressed concrete units laid on a base layer. Many permutations of design have been put forward.

However, ballastless track has a high initial cost, and in the case of existing railroads the upgrade to such requires closure of the route for a long period. Its whole-life cost can be lower because of the reduction in maintenance. Ballastless track is usually considered for new very high speed or very high loading routes, in short extensions that require additional strength (e.g. railway stations), or for localised replacement where there are exceptional maintenance difficulties, for example in tunnels. Most [[rapid transit]] lines and [[rubber-tyred metro]] systems use ballastless track.<ref>{{Cite web |url=http://www.infovisual.info/05/050_en.html |title=Showing part of the track |access-date=7 December 2016 |archive-date=16 June 2016 |archive-url=https://web.archive.org/web/20160616154008/http://infovisual.info/05/050_en.html |url-status=live }}</ref>

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===Continuous longitudinally supported track===
[[File:Diagram of section of ladder track type of sleeper on Leeds and Selby Railway.JPG|thumb|Diagram of cross section of 1830s ladder type track used on the [[Leeds and Selby Railway]]]]
[[File:FloatingLadder.JPG|thumb|Ladder track at [[Shinagawa Station]], Tokyo, Japan]]
Early railways (c.&nbsp;1840s) experimented with ''continuous bearing'' railtrack, in which the rail was supported along its length, with examples including Brunel's [[baulk road]] on the [[Great Western Railway]], as well as use on the [[Newcastle and North Shields Railway]],<ref>{{citation|url = https://books.google.com/books?id=JI5CAQAAIAAJ&pg=PA276|journal = American Railroad Journal and Mechanic's Magazine|volume = 13 (7 new series)|pages = 270–277, 298–304|title = On Cast Iron Rails for Railways|first = Ellwood|last = Morris|year = 1841|access-date = 20 November 2015|archive-date = 11 June 2016|archive-url = https://web.archive.org/web/20160611021453/https://books.google.com/books?id=JI5CAQAAIAAJ&pg=PA276|url-status = live}}</ref> on the [[Lancashire and Yorkshire Railway]] to a design by [[John Hawkshaw]], and elsewhere.<ref>{{Cite journal | last1 = Hawkshaw | first1 = J. | title = Description of the Permanent Way, of the Lancashire and Yorkshire, the Manchester and Southport, and the Sheffield, Barnsley and Wakefield Railways | doi = 10.1680/imotp.1849.24189 | journal = Minutes of the Proceedings | volume = 8 | issue = 1849 | pages = 261–262 | year = 1849 | url = https://books.google.com/books?id=ExzGAAAAMAAJ&pg=PA261 | access-date = 20 November 2015 | archive-date = 24 April 2016 | archive-url = https://web.archive.org/web/20160424080721/https://books.google.com/books?id=ExzGAAAAMAAJ&pg=PA261 | url-status = live }}</ref> Continuous-bearing designs were also promoted by other engineers.<ref>{{Cite journal | last1 = Reynolds | first1 = J. | doi = 10.1680/itrcs.1838.24387 | title = On the Principle and Construction of Railways of Continuous Bearing. (Including Plate) | journal = ICE Transactions | volume = 2 | pages = 73–86 | year = 1838 | url = https://books.google.com/books?id=qQ5AAAAAYAAJ&pg=PA73 | access-date = 20 November 2015 | archive-date = 3 June 2016 | archive-url = https://web.archive.org/web/20160603183638/https://books.google.com/books?id=qQ5AAAAAYAAJ&pg=PA73 | url-status = live }}</ref> The system was tested on the [[Baltimore and Ohio]] railway in the 1840s, but was found to be more expensive to maintain than rail with [[Railroad tie|cross sleepers]].<ref>{{citation | work= Annual report[s] of the Philadelphia, Wilmington and Baltimore Rail Road Company | volume= 4 | title= Eleventh Annual Report (1848) | pages= 17–20 | url= https://books.google.com/books?id=F4YpAAAAYAAJ&pg=PA129 | year= 1842 | access-date= 20 November 2015 | archive-date= 28 May 2016 | archive-url= https://web.archive.org/web/20160528214442/https://books.google.com/books?id=F4YpAAAAYAAJ&pg=PA129 | url-status= live }}</ref>

This type of track still exists on some bridges on Network Rail where the timber baulks are called waybeams or longitudinal timbers. Generally the speed over such structures is low.<ref>[https://www.networkrailmediacentre.co.uk/resources/re-installing-track-on-keb-following-waybeam-renewal-xmas-2018 "Waybeams at KEB, Newcastle] {{Webarchive|url=https://web.archive.org/web/20200903223328/https://www.networkrailmediacentre.co.uk/resources/re-installing-track-on-keb-following-waybeam-renewal-xmas-2018 |date=3 September 2020 }}, ''Network Rail Media Centre'', Retrieved 21 January 2020</ref>

Later applications of continuously supported track include [[Balfour Beatty]]'s 'embedded slab track', which uses a rounded rectangular rail profile (BB14072) embedded in a [[slipform]]ed (or pre-cast) concrete base (development 2000s).<ref>{{citation| url = http://www.innotrack.net/IMG/pdf/d233-f2p-design_manufacture_bbers_components.pdf| title = 2.3.3 Design and Manufacture of Embedded Rail Slab Track Components| publisher = Innotrack| date = 12 June 2008| access-date = 14 August 2012| archive-date = 5 March 2016| archive-url = https://web.archive.org/web/20160305011309/http://www.innotrack.net/IMG/pdf/d233-f2p-design_manufacture_bbers_components.pdf| url-status = dead}}</ref><ref>{{citation| url = http://www.railwaygazette.com/news/single-view/view/putting-slab-track-to-the-test.html| title = Putting slab track to the test| date = 1 October 2002| work = www.railwaygazette.com| access-date = 14 August 2012| archive-date = 12 December 2012| archive-url = https://web.archive.org/web/20121212014235/http://www.railwaygazette.com/news/single-view/view/putting-slab-track-to-the-test.html| url-status = live}}</ref> The 'embedded rail structure', used in the Netherlands since 1976, initially used a conventional UIC&nbsp;54 rail embedded in concrete, and later developed (late 1990s) to use a 'mushroom' shaped SA42 rail profile; a version for light rail using a rail supported in an [[asphalt concrete]]–filled steel trough has also been developed (2002).<ref>{{citation| url = http://www.esveld.com/Download/TUD/ERR_Slabtrack.pdf| title = Recent developments in slab track| first = Coenraad| last = Esveld| pages = 84–5| journal = European Railway Review| issue = 2| year = 2003| access-date = 14 August 2012| archive-date = 20 December 2016| archive-url = https://web.archive.org/web/20161220062609/http://www.esveld.com/Download/TUD/ERR_Slabtrack.pdf| url-status = live}}</ref>

Modern [[ladder track]] can be considered a development of baulk road. Ladder track utilizes sleepers aligned along the same direction as the rails with rung-like gauge restraining cross members. Both ballasted and ballastless types exist.

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==Rail==
[[File:Flat-bottom and bullhead rail profiles.png|thumb|Cross-sections of rail. Left: [[rail profile|flat-bottomed rail]], which is spiked, screwed or clipped directly to a [[Rail fastening system|sleeper]] ({{abbr|CwthE|Commonwealth English}}) or crosstie ({{abbr|AE|American English}}), or through a steel [[Rail fastening system#Tie plate|baseplate]], which protects the sleeper. Right: [[Rail profile|bullhead rail]], an older design used mainly in the [[United Kingdom|UK]], which sits in a cast-iron [[chair (railway)|chair]] with a timber or spring-steel [[Rail fastening system#Chairs|key]] to keep it secure.]]
{{Main|Rail profile}}
Modern track typically uses [[Hot rolling|hot-rolled]] steel with a [[profile (engineering)|profile]] of an asymmetrical rounded [[I-beam]].<ref>''A Metallurgical History of Railmaking'' Slee, David E. [[Australian Railway History]], February, 2004 pp43-56</ref> Unlike some other uses of [[iron]] and [[steel]], railway rails are subject to very high stresses and have to be made of very high-quality steel alloy. It took many decades to improve the quality of the materials, including the change from iron to steel. The stronger the rails and the rest of the trackwork, the heavier and faster the trains the track can carry.{{cn|date=March 2025}} 


Other profiles of rail include: [[bullhead rail]]; [[grooved rail]]; [[Rail profile#Flat bottomed rail|flat-bottomed rail]] (Vignoles rail or flanged T-rail); [[Rail profile#Bridge rail|bridge rail]] (inverted U–shaped used in [[baulk road]]); and [[Barlow rail]] (inverted V).

North American railroads until the mid- to late-20th century used rails {{convert|39|ft|1}} long so they could be carried in [[gondola (rail)|gondola cars]] ([[open wagons]]), often {{convert|40|ft|1}} long; as gondola sizes increased, so did rail lengths.

According to the ''[[Railway Gazette International]]'' the planned-but-cancelled 150-kilometre rail line for the [[Baffinland Iron Mine]], on [[Baffin Island]], would have used older [[carbon steel]] alloys for its rails, instead of more modern, higher performance alloys, because modern alloy rails can become brittle at very low temperatures.<ref name=RailwayGazette20080724>{{cite news| url=http://www.railwaygazette.com/news_view/article/2008/07/8652/heavy_haul_in_the_high_north.html| title=Heavy haul in the high north| publisher=[[Railway Gazette International]]| author=Carolyn Fitzpatrick| date=2008-07-24| access-date=2008-08-10| archive-url=https://archive.today/20090501133939/http://www.railwaygazette.com/news_view/article/2008/07/8652/heavy_haul_in_the_high_north.html| archive-date=2009-05-01| url-status=live| quote = Premium steel rails will not be used, because the material has an increased potential to fracture at very low temperatures. Regular carbon steel is preferred, with a very high premium on the cleanliness of the steel. For this project, a low-alloy rail with standard strength and a Brinell hardness in the range of 300 would be most appropriate.}}</ref>

=== Iron-topped wooden rails ===

Early North American railroads used iron on top of wooden rails as an economy measure but gave up this method of construction after the iron came loose, began to curl, and intruded into the floors of the coaches, leading early railroaders to refer to them as "snake heads".<ref>{{cite news| url=https://www.newspapers.com/clip/20355016/definition_of_snake_head/| title="Snake heads" held up early traffic| newspaper=[[Syracuse Herald-Journal]]| location=Syracuse, NY| date=March 20, 1939| page=77| via=Newspapers.com| access-date=25 May 2018| archive-date=25 May 2018| archive-url=https://web.archive.org/web/20180525204849/https://www.newspapers.com/clip/20355016/definition_of_snake_head/| url-status=live}} {{open access}}</ref><ref>{{cite web| url=https://aaronwmarrs.com/blog/2012/02/snakeheads-on-antebellum-railroads.html| title=Snakeheads on antebellum railroads| date=February 6, 2012| website=Frederick Jackson Turner Overdrive| access-date=29 June 2017| archive-date=18 October 2016| archive-url=https://web.archive.org/web/20161018215406/http://aaronwmarrs.com/blog/2012/02/snakeheads-on-antebellum-railroads.html| url-status=live}}</ref>

The [[Deeside Tramway]] in [[North Wales]] used this form of rail. It opened around 1870 and closed in 1947, with long sections still using these rails. It was one of the last uses of iron-topped wooden rails.<ref>{{cite book |first=Alun |last=Jones |title=The Slate Railways of Wales |publisher=Gwasg Carreg Gwalch |date=2001}}</ref>

===Rail classification (weight)===
{{Main|Rail profile}}
Rail is graded by its [[linear density]], that is, its mass over a standard length. Heavier rail can support greater axle loads and higher train speeds without sustaining damage than lighter rail, but at a greater cost. In North America and the United Kingdom, rail is graded in pounds per yard (usually shown as ''pound'' or ''lb''), so ''130-pound rail'' would weigh {{convert|130|lb/yd|kg/m|abbr=on}}. The usual range is {{convert|115|to|141|lb/yd|kg/m|abbr=on}}. In Europe, rail is graded in kilograms per metre and the usual range is {{convert|40|to|60|kg/m|lb/yd|abbr=on}}. The heaviest mass-produced rail was {{convert|155|lb/yd|kg/m}}, rolled for the [[Pennsylvania Railroad]].{{Citation needed|date=September 2024}}

==Rail lengths==
The rails used in [[rail transport]] are produced in sections of fixed length. Rail lengths are made as long as possible, as the joints between rails are a source of weakness. Throughout the history of rail production, lengths have increased as manufacturing processes have improved.

=== Timeline ===
The following are lengths of single sections produced by [[steel mill]]s, without any [[thermite welding]]. Shorter rails may be welded with [[Flash welding|flashbutt welding]], but the following rail lengths are unwelded.
* (1767) {{flagicon|United Kingdom}} [[Richard Reynolds (ironmaster)|Richard Reynolds]] laid the first iron rails at Coalbrookdale.<ref>{{cite book |first=Samuel |last=Smiles |author-link=Samuel Smiles |url=http://www.gutenberg.org/ebooks/404 |title=Industrial Biography: Iron Workers and Tool Makers}}</ref>
* (1825) {{flagicon|United Kingdom}} {{convert|15|ft|m|2}} [[Stockton and Darlington Railway]] {{convert|5.6|lb/yd|kg/m|2|abbr=on}}
* (1830) {{flagicon|United Kingdom}} {{convert|15|ft|m|2}} [[Liverpool and Manchester Railway]]. Fish-belly rails at {{convert|35|lb/yd|kg/m|1|abbr=on}}, laid mostly on stone blocks
* (1831) {{flagicon|United States}} {{convert|15|ft}} long and weighing {{convert|36|lb/yd|kg/m|1}}, reached [[Philadelphia]] the first use of the flanged T-rail in the United States
* (1880) {{flagicon|United States|1877}} {{convert|39|ft|m|2}} United States to suit {{convert|40|ft||2|adj=mid|-long}} [[Gondola (rail)|gondola cars]]
* (1928) {{flagicon|United Kingdom}} {{convert|45|and|60|ft|m|2}} [[London, Midland and Scottish Railway]]<ref name="LMS-PW-Drawings">[http://www.lmssociety.org.uk/assets/pdfs/permanentWay1928.pdf LMS Drawings of Standard Railway Equipment Permanent Way 1928] ([http://www.lmssociety.org.uk/ The LMS Society] - Resources)</ref>
* (1950) {{flagicon|United Kingdom}} {{convert|60|ft|m|2}} [[British Rail]]
* (1900) {{flagicon|United Kingdom}} {{convert|71|ft|m|1|abbr=on}} – steel works weighing machine for rails ([[steelyard balance]])<ref>{{cite news |url=http://nla.gov.au/nla.news-article71390997 |title=Big Weighing Machines. |newspaper=[[Australian Town and Country Journal |Australian Town and Country Journal (NSW : 1870–1907)]] |location=NSW |date=4 August 1900 |access-date=8 October 2011 |page=19 |via=National Library of Australia |archive-date=20 April 2021 |archive-url=https://web.archive.org/web/20210420071026/https://trove.nla.gov.au/newspaper/article/71390997 |url-status=live }}</ref>
* (1940s) {{flagicon|United States|1912}} {{convert|78|ft|m|2}} – double 39&nbsp;ft<ref>{{cite news|last1=McGonigal|first1=Robert|title=Rail|url=http://trn.trains.com/en/Railroad%20Reference/ABCs%20of%20Railroading/2006/05/Rail.aspx|access-date=10 September 2014|work=ABC's of Railroading|publisher=Trains|date=1 May 2014|archive-date=11 September 2014|archive-url=https://web.archive.org/web/20140911001918/http://trn.trains.com/en/Railroad%20Reference/ABCs%20of%20Railroading/2006/05/Rail.aspx|url-status=live}}</ref>
* (1953) {{Flagicon|Australia}} {{convert|45|ft|m|2}} Australia<ref>{{cite news |url=http://nla.gov.au/nla.news-article48273211 |title=Surveys Of New Rail Link. |newspaper=[[The Advertiser (Adelaide)|The Advertiser]] |location=Adelaide, SA |date=17 June 1953 |access-date=3 October 2012 |page=5 |via=National Library of Australia |archive-date=20 April 2021 |archive-url=https://web.archive.org/web/20210420071022/https://trove.nla.gov.au/newspaper/article/48273211 |url-status=live }}</ref>

Welding of rails into longer lengths was first introduced around 1893, making train rides quieter and safer. With the introduction of thermite welding after 1899, the process became less labour-intensive, and ubiquitous.<ref name=Goldschmidt>{{cite web|title=Thermit®|url=http://history.evonik.com/sites/geschichte/en/inventions/thermit/pages/default.aspx|website=Evonik Industries|publisher=Evonik Industries AG|access-date=9 May 2019|archive-date=9 May 2019|archive-url=https://web.archive.org/web/20190509175238/https://history.evonik.com/sites/geschichte/en/inventions/thermit/pages/default.aspx|url-status=live}}</ref>

* (1895) {{flagicon|Germany|empire}} [[Hans Goldschmidt]] developed [[exothermic welding]]
* (1899) {{flagicon|Germany|empire}} the [[Trams in Essen|Essen Tramway]] became the first railway to use thermite welding; also suited [[track circuit]]s
* (1904) {{flagicon|United States|1896}} George Pellissier welded the [[Holyoke Street Railway#Pioneering thermite rail welding|Holyoke Street Railway]], first to use the process in the Americas
* (1935) {{flagicon|United States|1912}} [[Charles Cadwell]] developed non-ferrous [[exothermic welding]]
* (1950) {{flagicon|Australia}} {{convert|240|ft|m|1|abbr=on}} welded – (4 x {{convert|60|ft|m|1|disp=or}})<ref>{{cite news |url=http://nla.gov.au/nla.news-article50202941 |title=Opening Of S.-E. Broad Gauge line. |newspaper=[[The Advertiser (Adelaide)|The Advertiser]] |location=Adelaide, SA |date=2 February 1950 |access-date=8 December 2011 |page=1 |via=National Library of Australia |archive-date=20 April 2021 |archive-url=https://web.archive.org/web/20210420071022/https://trove.nla.gov.au/newspaper/article/50202941 |url-status=live }}</ref>

Modern production techniques allowed the production of longer unwelded segments.
* (2007) {{flagicon|United Kingdom}} {{convert|108|m|ft|1}} Corus (now [[British Steel (2016–present)]]<ref>{{Cite web |title=Production of long-welded and continuous-welded rail |url=https://www.railtechnologymagazine.com/Rail-News/production-of-long-welded-and-continuous-welded-rail |access-date=2024-01-04 |website=www.railtechnologymagazine.com}}</ref>)
* (2011) {{flagicon|France}} {{convert|108|m|ft|1}} [[Tata Steel Europe]]<ref>{{Cite web |title=Tata Steel unveils upgraded rail manufacturing plant in France |url=https://www.tatasteeleurope.com/corporate/news/tata-steel-hayange-upgrade |access-date=2024-01-04 |website=Tata Steel in Europe |language=en}}</ref>
* (2011) {{flagicon|Austria}} {{convert|120|m|ft|1}} [[Voestalpine]],<ref>{{cite web|title=Ultra-long rails|url=http://www.voestalpine.com/schienen/en/products/Ultra-long_rails/|website=voestalpine|publisher=voestalpine AG|access-date=10 September 2014|archive-date=10 September 2014|archive-url=https://web.archive.org/web/20140910195803/http://www.voestalpine.com/schienen/en/products/Ultra-long_rails/|url-status=live}}</ref>
* (2011) {{flagicon|India}} {{convert|121|m|ft|1}} [[Jindal Steel and Power|Jindal]]<ref>{{cite web|title=Rails|url=http://www.jindalsteelpower.com/products/rail.html|publisher=Jindal Steel & Power Ltd.|access-date=10 September 2014|archive-date=10 September 2014|archive-url=https://web.archive.org/web/20140910215736/http://www.jindalsteelpower.com/products/rail.html|url-status=live}}</ref>
* (2014) {{flagicon|Japan}} 150 metres (492.1 ft) [[Nippon Steel]]<ref>{{Cite web |title=NSSMC Is Ready to Manufacture and Ship the World Longest Railway Rails: 150-Meter Rails |url=https://www.nipponsteel.com/en/news/20140416_100.html |access-date=2025-03-18 |website=www.nipponsteel.com}}</ref>

===Multiples===
Newer longer rails tend to be made as simple multiples of older shorter rails, so that old rails can be replaced without cutting and the same wagons can be used for transportation.{{Clarify|date=January 2025|reason=This can be interpreted in several ways}} Some cutting would be needed as slightly longer rails are needed on the outside of sharp curves compared to the rails on the inside.{{Citation needed|date=January 2025}}

===Boltholes===
Rails can be supplied pre-drilled with boltholes for [[fishplates]] or without where they will be welded into place. There are usually two or three boltholes at each end.{{Citation needed|date=January 2025}}

==Joining rails==
Rails are produced in fixed lengths and need to be joined end-to-end to make a continuous surface on which trains may run. The traditional method of joining the rails is to bolt them together using metal [[fishplate]]s (jointbars in the US), producing ''jointed track''. For more modern usage, particularly where higher speeds are required, the lengths of rail may be welded together to form ''continuous welded rail'' (CWR).

===Jointed track===
[[File:THORN-155lb-PS-jointed-joint.jpg|thumb|Mainline, six-bolt rail joint on a segment of {{convert|155|lb/yd|kg/m|1|abbr=on}} rail. The alternating bolt head orientation prevents joint separation should a derailed wheel strike the bolts.  The electrical bonding jumper connects the two rails to maintain [[continuity test|continuity]] of the [[track circuit]].]]
Jointed track is made using lengths of rail, usually about {{cvt|20|m|ft|0}} long (in the UK) and {{cvt|39|or|78|ft|m|0}} long (in North America), bolted together using perforated steel plates known as ''fishplates'' (UK) or ''joint bars'' (North America).

Fishplates are usually {{cvt|600|mm|ft|0}} long, used in pairs either side of the rail ends and [[Bolted joint|bolted]] together (usually four, but sometimes six [[Machine screw|bolts]] per joint). The bolts have alternating orientations so that in the event of a [[derailment]] and a wheel [[flange]] striking the joint, only some of the bolts will be sheared, reducing the likelihood of the rails misaligning with each other and worsening the derailment. This technique is not applied universally; European practice is to have all the bolt heads on the same side of the rail.

Small gaps which function as [[expansion joint]]s are deliberately left between the rail ends to allow for expansion of the rails in hot weather. European practice was to have the rail joints on both rails adjacent to each other; North American practice is to stagger them. Because of these small gaps, when trains pass over jointed tracks they make a "clickety-clack" sound, and in time the rail ends are deflected downwards. Unless it is well-maintained, jointed track does not have the ride quality of welded rail and is not suitable for [[high speed train]]s. However, jointed track is still used in many countries on lower-speed lines and [[siding (rail)|sidings]], and is used extensively in poorer countries due to the lower construction cost and the simpler equipment required for its installation and maintenance.

A major problem of jointed track is cracking around the bolt holes, which can lead to breaking of the rail head (the running surface). This was the cause of the [[Hither Green rail crash]] which caused [[British Rail]]ways to begin converting much of its track to continuous welded rail.

====Insulated joints====
Where [[track circuit]]s exist for [[railway signalling|signalling]] purposes, insulated block joints are required. These compound the weaknesses of ordinary joints. Specially-made glued joints, where all the gaps are filled with [[epoxy|epoxy resin]], increase the strength again.

As an alternative to the insulated joint, [[audio frequency]] track circuits can be employed using a [[LC circuit|tuned loop]] formed in approximately {{cvt|20|m|ft|0}} of the rail as part of the blocking circuit. Some insulated joints are unavoidable within turnouts.

Another alternative is an [[axle counter]], which can reduce the number of track circuits and thus the number of insulated rail joints required.

===Continuous welded rail===
[[File:Geschweisster schienenstoss.jpeg|thumb|Welded rail joint]]
[[File:LIRR-Winter-Flames.jpg|thumb|A pull-apart on the [[Long Island Rail Road]] [[Babylon Branch]] being repaired by using flaming rope to expand the rail back to a point where it can be joined together]]

Most modern railways use ''continuous welded rail'', sometimes referred to as ''ribbon rails'' or ''seamless rails''. In this form of track, the rails are [[welding|welded]] together by utilising [[Flash welding|flash butt welding]] to form one continuous rail that may be several kilometres long. Because there are few joints, this form of track is very strong, gives a smooth ride, and needs less maintenance; trains can travel on it at higher speeds and with less friction. Welded rails are more expensive to lay than jointed tracks, but have much lower maintenance costs. The first welded track was used in Germany in 1924.<ref>{{cite web
|url= http://www.arema.org/eseries/scriptcontent/custom/e_arema/library/1999_Conference_Proceedings/00059.pdf
|title= Thermite Rail Welding: History, Process Developments, Current Practices And Outlook For The 21st Century
|access-date= 2008-07-06
|author= C. P. Lonsdale
|date= September 1999
|work= Proceedings of the AREMA 1999 Annual Conferences
|publisher= The [[American Railway Engineering and Maintenance-of-Way Association]]
|page= 2
|archive-date= 10 October 2008
|archive-url= https://web.archive.org/web/20081010055956/http://www.arema.org/eseries/scriptcontent/custom/e_arema/library/1999_Conference_Proceedings/00059.pdf
|url-status= live
}}</ref> and has become common on [[Main line (railway)|main lines]] since the 1950s.

The preferred process of flash butt welding involves an automated track-laying machine running a strong [[electric current]] through the touching ends of two unjoined rails. The ends become white hot due to electrical resistance and are then pressed together forming a strong weld. [[Thermite welding]] is used to repair or splice together existing continuous welded rail segments. This manual process requires a reaction crucible and form to contain the molten iron.

North American practice is to weld {{convert|1/4|mi|m|adj=mid|-long}} segments of rail at a rail facility and load it on a special train to carry it to the job site. This train is designed to carry many segments of rail which are placed so they can slide off their racks to the rear of the train and be attached to the ties (sleepers) in a continuous operation.<ref>{{cite web |title=Welded Rail Trains, CRHS Conrail Photo Archive |url=http://conrailphotos.thecrhs.org/node/11104 |website=conrailphotos.thecrhs.org |date=3 October 2009 |access-date=27 June 2017 |archive-date=7 November 2017 |archive-url=https://web.archive.org/web/20171107030140/http://conrailphotos.thecrhs.org/node/11104 |url-status=live }}</ref>

If not restrained, rails would lengthen in hot weather and shrink in cold weather. To provide this restraint, the rail is prevented from moving in relation to the sleeper by use of clips or anchors. Attention needs to be paid to compacting the ballast effectively, including under, between, and at the ends of the sleepers, to prevent the sleepers from moving. Anchors are more common for wooden sleepers, whereas most concrete or steel sleepers are fastened to the rail by special clips that resist longitudinal movement of the rail. There is no theoretical limit to how long a welded rail can be. However, if longitudinal and lateral restraint are insufficient, the track could become distorted in hot weather and cause a derailment. Distortion due to heat expansion is known in North America as [[sun kink]], and elsewhere as buckling. In extreme hot weather special inspections are required to monitor sections of track known to be problematic. In North American practice, extreme temperature conditions will trigger slow orders to allow for crews to react to buckling or "sun kinks" if encountered.<ref>{{Cite book |chapter-url=https://www.researchgate.net/publication/300500772 |chapter=Rail Temperature Approximation and Heat Slow Order Best Practices |language=en |doi=10.1115/JRC2015-5720 |title=2015 Joint Rail Conference |pages=V001T04A002 |year=2015 |last1=Bruzek |first1=Radim |last2=Trosino |first2=Michael |last3=Kreisel |first3=Leopold |last4=Al-Nazer |first4=Leith |isbn=978-0-7918-5645-1 |access-date=27 June 2017 |archive-date=20 April 2021 |archive-url=https://web.archive.org/web/20210420071021/https://www.researchgate.net/publication/300500772_Rail_Temperature_Approximation_and_Heat_Slow_Order_Best_Practices |url-status=live }}</ref> The German railway company [[Deutsche Bahn]] is starting to paint rails white to lower the peak temperatures reached in summer days.<ref>{{Cite news|title=Cooling paintcover for rails|url=https://www.deutschebahn.com/de/presse/pressestart_zentrales_uebersicht/Kuehlender-Farbanstrich-fuer-Schienen--5316118|access-date=31 March 2021|archive-date=20 January 2021|archive-url=https://web.archive.org/web/20210120173250/https://www.deutschebahn.com/de/presse/pressestart_zentrales_uebersicht/Kuehlender-Farbanstrich-fuer-Schienen--5316118|url-status=live}}</ref>

After new segments of rail are laid, or defective rails replaced (welded-in), the rails can be artificially stressed if the temperature of the rail during laying is cooler than what is desired. The [[Rail stressing|stressing process]] involves either heating the rails, causing them to expand,<ref>{{cite web| url=http://www.grandadsez.co.uk/railways/continuous-rail.html| title=Continuous Welded Rail| work=Grandad Sez: Grandad's Railway Engineering Section| access-date=2006-06-12| archive-url=https://web.archive.org/web/20060218231247/http://www.grandadsez.co.uk/railways/continuous-rail.html| archive-date=18 February 2006| url-status=dead| df=dmy-all}}</ref> or stretching the rails with [[hydraulics|hydraulic]] equipment. They are then fastened (clipped) to the sleepers in their expanded form. This process ensures that the rail will not expand much further in subsequent hot weather. In cold weather the rails try to contract, but because they are firmly fastened, cannot do so. In effect, stressed rails are a bit like a piece of stretched [[Elastomer|elastic]] firmly fastened down. In extremely cold weather, rails are heated to prevent "pull aparts".<ref>{{cite news |last1=Holder |first1=Sarah |title=In Case of Polar Vortex, Light Chicago's Train Tracks on Fire |url=https://www.citylab.com/transportation/2019/01/polar-vortex-2019-chicago-train-metra-rail-tracks-on-fire/581635/ |access-date=30 January 2019 |work=[[The Atlantic#CityLab|CityLab]] |publisher=[[Atlantic Media]] |date=30 January 2018 |archive-date=31 January 2019 |archive-url=https://web.archive.org/web/20190131032230/https://www.citylab.com/transportation/2019/01/polar-vortex-2019-chicago-train-metra-rail-tracks-on-fire/581635/ |url-status=live }}</ref>

Continuous welded rails, complete with fastenings, are laid at a temperature known as "rail neutral temperature" that is approximately midway between the extremes experienced at that location.  This installation procedure is intended to prevent tracks from buckling in summer heat or pulling apart in the winter cold. In North America, because broken rails are typically detected by interruption of the current in the signaling system, they are seen as less of a potential hazard than undetected heat kinks.

[[File:Expansion joint, Hayle.jpg|thumb|An expansion joint on the [[Cornish Main Line]], England]]
Joints are used in the continuous welded rail when necessary, usually for signal circuit gaps. Instead of a joint that passes straight across the rail, the two rail ends are sometimes cut at an angle to give a smoother transition. In extreme cases, such as at the end of long bridges, a [[breather switch]] (referred to in North America and Britain as an ''expansion joint'') gives a smooth path for the wheels while allowing the end of one rail to expand relative to the next rail.

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==Sleepers==
{{Main|Railroad tie}}
A sleeper (tie or crosstie) is a rectangular object on which the rails are supported and fixed. The sleeper has two main roles: to transfer the loads from the rails to the [[track ballast]] and the ground underneath, and to hold the rails to the correct width apart (to maintain the [[rail gauge]]). They are generally laid transversely to the rails.

===Fixing rails to sleepers===
{{Main|Rail fastening system}}
Various methods exist for fixing the rail to the sleeper. Historically, rails were spiked directly on to ties, the practice giving way baseplates being fitted between the rails and sleepers; subsequently, spikes were replaced by sprung steel clips, such as ''[[Pandrol]] clips'', to fix the rail to the baseplates.

==Portable track==
[[File:Panama Canal under construction, 1907.jpg|upright=0.9|thumb|Panama Canal construction track, 1907]]
Sometimes rail tracks are designed to be portable and moved from one place to another as required. During construction of the [[Panama Canal]], tracks were moved around excavation works. These track gauge were {{Track gauge|5ft|lk=on}} and the rolling stock full size. Portable tracks have often been used in open pit mines. In 1880 in [[New York City]], sections of heavy portable track (along with much other improvised technology) helped in the move of the [[Cleopatra's Needle (New York City)|ancient obelisk in Central Park]] to its final location from the dock where it was unloaded from the cargo ship ''[[SS Dessoug]]''.

[[Sugarcane|Cane]] railways often had permanent tracks for the main lines, with portable tracks serving the canefields themselves. These tracks were [[Narrow-gauge railway|narrow-gauge]] (for example, {{Track gauge|2ft|lk=on}}) and the portable track came in straights, curves, and turnouts, rather like on a model railway.<ref>[[Narrow Gauge Down Under]] magazine, January 2010, p. 20.</ref>

[[Decauville]] was a source of many portable light rail tracks, also used for military purposes.
{{Anchor|A-temporary-way}}
The ''permanent way'' is so called because ''temporary way'' tracks were often used in the construction of that permanent way.<ref>{{cite book |title=Permanent-way Material, Platelaying, and Points and Crossings |first=William Henry |last=Cole |publisher=R. & F.N. Spon |date=1915 |page=1 |url=https://books.google.com/books?id=LVBCAQAAMAAJ}}</ref>

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==Layout==
{{Main|Track geometry}}
The geometry of the tracks is three-dimensional by nature, but the standards that express the speed limits and other regulations in the areas of track gauge, alignment, elevation, curvature and track surface are usually expressed in two separate layouts for [[Horizontal plane|horizontal]] and [[Vertical direction|vertical]].

Horizontal layout is the track layout on the [[Multiview orthographic projection#Plan|horizontal plane]]. This involves the layout of three main track types: ''tangent track'' (straight line), ''curved track'', and ''[[track transition curve]]'' (also called ''transition spiral'' or ''spiral'') which connects between a tangent and a curved track.

Vertical layout is the track layout on the [[Multiview orthographic projection#Elevation|vertical plane]] including the concepts such as crosslevel, [[Cant (road/rail)|cant]] and [[Grade (slope)|gradient]].<ref>{{cite book|title=PART 1025 Track Geometry|year=2008|publisher=Department of Planning Transport, and Infrastructure - Government of South Australia|url=http://www.dpti.sa.gov.au/__data/assets/word_doc/0004/40684/Part_1025_Rail_Track_geometry.doc|edition=Issue 2 – 07/10/08|access-date=19 November 2012|archive-date=28 April 2013|archive-url=https://web.archive.org/web/20130428113140/http://www.dpti.sa.gov.au/__data/assets/word_doc/0004/40684/Part_1025_Rail_Track_geometry.doc|url-status=live}}</ref><ref>{{cite book|title=Track Standards Manual - Section 8: Track Geometry|date=December 1998|publisher=Railtrack PLC|url=http://www.rgsonline.co.uk/Railway_Group_Standards/Infrastructure/Railway%20Group%20Standards/GCRT5017%20Iss%202.pdf|access-date=13 November 2012|archive-date=29 March 2014|archive-url=https://web.archive.org/web/20140329011159/http://www.rgsonline.co.uk/Railway_Group_Standards/Infrastructure/Railway%20Group%20Standards/GCRT5017%20Iss%202.pdf|url-status=live}}</ref>

A ''sidetrack'' is a railroad track other than [[siding (rail)|siding]] that is auxiliary to the main track. The word is also used as a verb (without object) to refer to the movement of trains and railcars from the main track to a siding, and in common parlance to refer to giving in to distractions apart from a main subject.<ref>{{Cite web |url=http://dictionary.reference.com/browse/sidetrack?s=t |title=Dictionary.com |access-date=17 July 2017 |archive-date=4 March 2016 |archive-url=https://web.archive.org/web/20160304083726/http://dictionary.reference.com/browse/sidetrack?s=t |url-status=live }}</ref> Sidetracks are used by railroads to order and organise the flow of rail traffic.

===Gauge===
{{Main|Track gauge|List of track gauges|List of tram track gauges}} 
[[File:Gauge EN.svg|thumb|center|350px|Measuring rail gauge]]
During the early days of rail, there was considerable variation in the gauge used by different systems, and in the UK during the railway building boom of the 1840s Brunel's broad gauge of {{RailGauge|7ft 1/4in|lk=on}} was in [[British Gauge War|competition]] with what was referred to at the time as the 'narrow' gauge of {{Track gauge|1435mm}}. Eventually the {{Track gauge|1435mm}} gauge won the battle, and became the standard gauge, with the term 'narrow gauge' henceforth used for gauges narrower than the new standard. {{As of|2017}}, about 60% of the world's railways use a gauge of {{Track gauge|1435mm}}, known as [[Standard gauge|standard]] or international gauge<ref>{{Cite web|url=http://www.inventingeurope.eu/governance/a-port-in-the-hungarian-hinterland&object|title=Dual gauge (1435mm-1520 mm) railway track on the Hungary-Ukraine border - Inventing Europe|website=www.inventingeurope.eu|access-date=2019-10-01|archive-date=5 June 2020|archive-url=https://web.archive.org/web/20200605100008/http://www.inventingeurope.eu/governance/a-port-in-the-hungarian-hinterland%26object|url-status=dead}}</ref><ref>{{Cite web|url=http://chartsbin.com/view/38573|title=Railway Track Gauges by Country|last=ChartsBin|website=ChartsBin|access-date=2019-10-01|archive-date=1 October 2019|archive-url=https://web.archive.org/web/20191001140753/http://chartsbin.com/view/38573|url-status=live}}</ref> Gauges wider than standard gauge are called [[broad gauge]]; narrower, [[narrow-gauge railway|narrow gauge]]. Some stretches of track are [[dual gauge]], with three (or sometimes four) parallel rails in place of the usual two, to allow trains of two different gauges to use the same track.<ref>{{cite web |url=http://finance.groups.yahoo.com/group/1520mm/message/90710|title=Message in the mailing list '1520mm' on Р75 rails |access-date=16 March 2007 |archive-date=5 July 2009 |archive-url=https://web.archive.org/web/20090705135244/http://finance.groups.yahoo.com/group/1520mm/message/90710 |url-status=dead}}</ref>

Gauge can safely vary over a range. For example, U.S. federal safety standards allow standard gauge to vary from {{convert|4|ft|8|in|mm|abbr=on}} to {{convert|4|ft|9+1/2|in|mm|abbr=on}} for operation up to {{convert|60|mph|km/h|abbr=on}}.<ref>{{cite report |date=10 January 2011 |title=Part 13 — Track Safety Standards: Title 49, Transportation - Code of Federal Regulations |url=https://www.govinfo.gov/content/pkg/CFR-2011-title49-vol4/pdf/CFR-2011-title49-vol4-part213.pdf |publisher=[[Office of the Federal Register]], [[National Archives and Records Administration]] |page=7 |access-date=14 January 2024}}</ref>

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==Maintenance==
{{Main|Maintenance of way}}
{{Further|Rail inspection|Work train}}
{{See also|Railroad car#Non-revenue cars}}
[[File:Sectiongang hungerford1917.jpg|thumb|right|Circa 1917, an American section gang ([[gandy dancer]]s) responsible for maintenance of a particular section of railway. One man is holding a lining bar (gandy), while others are using rail tongs to position a rail. [[Cant (road and rail)|Superelevation]] (cant) is clearly evident on the curve.]]

Track needs regular maintenance to remain in good order, especially when high-speed trains are involved. Inadequate maintenance may lead to a "slow order" (North American terminology, or [[Slow zone#Speed restrictions in the United Kingdom|temporary speed restriction]] in the United Kingdom) being imposed to avoid accidents (see [[Slow zone]]). Track maintenance was at one time hard [[manual labour]], requiring teams of labourers, or trackmen (US: [[gandy dancer]]s; UK: [[platelayer]]s; Australia: fettlers or packers) under the supervision of a skilled ganger, who used lining bars to correct irregularities in horizontal alignment (line) of the track, and tamping and jacks to correct vertical irregularities (surface). Currently, maintenance is facilitated by a variety of specialised machines.

[[File:Track Flange Oiler.JPG|thumb|right|Flange oilers lubricate wheel flanges to reduce rail wear in tight curves, [[Middelburg, Mpumalanga]], South Africa]]
The surface of the head of each of the two rails can be maintained by using a [[railgrinder]].

Common maintenance jobs include changing sleepers, lubricating and adjusting [[Railroad switch|switches]], tightening loose track components, and surfacing and lining track to keep straight sections straight and curves within maintenance limits. The process of sleeper and rail replacement can be automated by using a [[track renewal train]].

Spraying ballast with [[herbicide]] to prevent weeds growing through and redistributing the ballast is typically done with a special weed killing train.

Over time, ballast is crushed or moved by the weight of trains passing over it, periodically requiring relevelling ("tamping") and eventually to be cleaned or replaced. If this is not done, the tracks may become uneven, causing swaying, rough riding and possibly derailments. An alternative to tamping is to lift the rails and sleepers and reinsert the ballast beneath. For this, specialist "[[stoneblower]]" trains are used.

[[Rail inspection]]s utilize [[nondestructive testing]] methods to detect internal flaws in the rails. This is done by using specially equipped [[Road-rail vehicle|HiRail trucks]], inspection cars, or in some cases, handheld inspection devices.

Rails must be replaced before the railhead profile wears to a degree that may trigger a derailment. Worn mainline rails usually have sufficient life remaining to be used on a [[branch line]], [[siding (rail)|siding]] or [[Railroad terminology#S|stub]] afterwards and are "cascaded" to those applications.

The environmental conditions along railroad track create a unique [[railroad ecology|railway ecosystem]]. This is particularly so in the United Kingdom, where steam locomotives are only used on special services and vegetation has not been trimmed back so thoroughly. This creates a fire risk in prolonged dry weather.

In the UK, the [[cess (rail transport)|cess]] is used by track repair crews to walk to a work site, and as a safe place to stand when a train is passing. This helps when doing minor work, while needing to keep trains running, by not needing a Hi-railer or transport vehicle blocking the line to transport crew to get to the site.

<gallery mode="packed" class="center">
 File:Risanatrice.jpg|Maintenance of way equipment in Italy
 File:Maintenance of way.jpg|A [[track renewal train]] in [[Pennsylvania]]
 File:Plasser & Theurer 09-32 CSM CFR.jpg| [[Plasser & Theurer]] 09-32 CSM continuous action levelling, lining and tamping machine of the [[Căile Ferate Române|Romanian Railways]]
</gallery>

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==Bed and foundation==
[[File:Toyohashi Station 001.JPG|thumb|right|On this Japanese high-speed line, mats have been added to stabilize the ballast.]]
Railway tracks are generally laid on a bed of stone [[track ballast]] or [[track bed]], which in turn is supported by prepared earthworks known as the track formation. The formation comprises the [[land grading|subgrade]] and a layer of sand or stone dust (often sandwiched in impervious plastic), known as the blanket, which restricts the upward migration of wet clay or silt. There may also be layers of waterproof fabric to prevent water penetrating to the subgrade. The track and ballast form the [[permanent way: historical development|permanent way]]. The foundation may refer to the ballast and formation, i.e. all man-made structures below the tracks.

Some railroads are using asphalt pavement below the ballast in order to keep dirt and moisture from moving into the ballast and spoiling it. The fresh asphalt also serves to stabilize the ballast so it does not move around so easily.<ref>{{cite web |title=Hot Mix Asphalt Railway Trackbeds: Trackbed Materials, Performance Evaluations, and Significant Implications |url=https://web.engr.uky.edu/~jrose/papers/Hot%20Mix%20Asphalt%20Railway%20Trackbeds.pdf |website=web.engr.uky.edu |access-date=21 January 2019 |archive-date=21 January 2019 |archive-url=https://web.archive.org/web/20190121121849/https://web.engr.uky.edu/~jrose/papers/Hot%20Mix%20Asphalt%20Railway%20Trackbeds.pdf |url-status=live }}</ref>

Additional measures are required where the track is laid over [[permafrost]], such as on the [[Qingzang Railway]] in [[Tibet]]. For example, transverse pipes through the subgrade allow cold air to penetrate the formation and prevent that subgrade from melting.

=== Geosynthetic reinforcement ===
[[Geosynthetics]] are used to reduce or replace traditional layers in trackbed construction and rehabilitation worldwide to improve track support and reduce track maintenance costs.<ref>{{cite book |doi=10.3389/978-2-88966-741-3 |doi-access=free |title=Geosynthetics for Development of Transportation Infrastructures |series=Frontiers Research Topics |year=2021 |isbn=9782889667413 }}</ref><ref>Geosynthetics in Railways: Applications & Benefits. International Geosynthetics Society. https://igs2.wpengine.com/wp-content/uploads/2021/04/IGS_Geosynthetics_Railways_Leaflet.pdf. Accessed 28 JUN 2022.</ref> Reinforcement geosynthetics, such as [[Cellular confinement|geocells]]<ref>Leshchinsky, B. (2011) Enhancing Ballast Performance using Geocell Confinement. Advances in Geotechnical Engineering, publication of Geo-Frontiers 2011 conference, Dallas, Texas, USA, March 13–16.</ref> (which rely on 3D soil confinement mechanisms) have demonstrated efficacy in stabilizing soft subgrade soils and reinforcing substructural layers to limit progressive track degradation. Reinforcement geosynthetics increase soil bearing capacity, limit ballast movement and degradation and reduce differential settlement that affects track geometry.<ref>{{cite journal |last1=Zarembski |first1=Allan M. |last2=Palese |first2=Joseph |last3=Hartsough |first3=Christopher M. |last4=Ling |first4=Hoe I. |last5=Thompson |first5=Hugh |title=Application of Geocell Track Substructure Support System to Correct Surface Degradation Problems Under High-Speed Passenger Railroad Operations |year=2017 |journal=Transportation Infrastructure Geotechnology |volume=4 |issue=4 |pages=106–125 |s2cid=256401992 |doi=10.1007/s40515-017-0042-x |bibcode=2017TrIG....4..106Z }}</ref> They also reduce construction time and cost, while reducing environmental impact and carbon footprint.<ref>{{cite journal |url=https://core.ac.uk/download/pdf/61692286.pdf |last1=Pokharel |first1=S.K. |last2=Norouzi |first2=M. |last3=Martin |first3=I. |last4=Breault |first4=M. |title=Sustainable road construction for heavy traffic using high strength polymeric geocells |journal=Canadian Society of Civil Engineers Annual Conference on Resilient Infrastructure |date=June 4, 2016 |location=London, Ontario }}</ref> The increased use of geosynthetic reinforcement solutions is supported by new high-performance geocell materials (e.g., NPA - [[Novel polymeric alloy|Novel Polymeric Alloy]]), published research, case studies projects and international standards (ISO,<ref>ISO Standard WD TR 18228-5. (2018). Design using Geosynthetics – Part 5: Stabilization. International Organization for Standardization. Geneva, Switzerland. Under development.</ref> ASTM,<ref>{{cite journal |url=https://doi.org/10.1520/D8269-21 |date=August 12, 2021 |journal=ASTM |doi=10.1520/D8269-21 |title=Standard Guide for the Use of Geocells in Geotechnical and Roadway Projects |url-access=subscription }}</ref> CROW/SBRCURnet<ref>Vega, E., van Gurp, C., Kwast, E. (2018). Geokunststoffen als Funderingswapening in Ongebonden Funderingslagen (Geosynthetics for Reinforcement of Unbound Base and Subbase Pavement Layers), CROW/SBRCURnet, Netherlands. Publication C1001 (Dutch).</ref>)

The hybrid use of high-performance geogrids at the subgrade and high-performance geocell in the upper subbase/subballast layer has been shown to increase the reinforcement factor greater than their separate sums, and is particularly effective in attenuating heaving of expansive subgrade clay soils.<ref>Kief, O. (2016) Rail Track Pavements on Expansive Clay Restrained by Hybrid Geosynthetic Solution. Geosynthetics 2016 Conference Proceedings. Miami Beach, FL. April.</ref> A field test project on [[Amtrak]]'s NE Corridor suffering clay mud-pumping demonstrated how the hybrid solution improved track quality index (TQI) significantly reduced track geometry degradation and lowered track surface maintenance by factor of 6.7x utilizing high-performance NPA geocell.<ref>Palese, J.W., Zarembski, A.M., Thompson, H., Pagano, W., and Ling, H.I. (2017). Life Cycle Benefits of Subgrade Reinforcement Using Geocell on a Highspeed Railway – a Case Study. AREMA Conference Proceedings (American Railway Engineering and Maintenance-of-Way Association). Indianapolis, IN, USA, September.</ref> Geosynthetic reinforcement is also used to stabilize railway embankments, which must be robust enough to withstand repeated cyclical loading. Geocells can utilize recycled marginal or poorly graded granular material to create stable embankments, make railway construction more economical and sustainable.<ref>{{cite journal |last1=Pokharel |first1=Sarah |last2=Breault |first2=Marc |title=NPA Geocell for Railway Line Repair in Permafrost Region. |publisher=Industrial Fabrics Association International |journal=Geosynthetics Magazine Online |date=June 1, 2021 |issn=0882-4983 |url=https://geosyntheticsmagazine.com/2021/06/01/npa-geocell-for-railway-line-repair-in-permafrost-region/ |accessdate=29 June 2022 }}</ref><ref>{{cite journal |title=Use of geogrid in the construction of railroads |year=2016 |last1=Das |first1=Braja M. |journal=Innovative Infrastructure Solutions |volume=1 |issue=1 |article-number=15 |s2cid=114993446 |doi=10.1007/s41062-016-0017-8 |doi-access=free |bibcode=2016InnIS...1...15D }}</ref><ref>Skok, D.M. and Russo, C. (2020) Embankment Foundation of Sant Martin Railway Viaduct, GeoAmericas 2020, October 26–29, Rio de Janeiro.</ref>

==Buses==
[[File:Scania K280UB O-Bahn Bus.jpg|thumb|Bus on a guided busway, [[Adelaide]], Australia]]
{{main|Guided bus}}
Some buses can use tracks. This concept came out of Germany and was called {{interlanguage link|O-Bahn|de|O-Bahn}}. The first such track, the [[O-Bahn Busway]], was built in Adelaide, Australia.

==See also==
{{Portal|Trains}}
{{div col|colwidth=20em}}
* [[Degree of curvature]]
* [[Comparison of train and tram tracks|Difference between train and tram rails]]
* [[Exothermic welding]]
* [[Gauntlet track]]
* [[Glossary of rail terminology]]<br> (including US/UK and other<br> regional/national differences)
* [[Green track]]
* [[Maglev]]
* [[Minimum railway curve radius]]
* [[Monorail]]
* [[Permanent way (history)]]
* [[Rack railway]]
* [[Rail profile]]
* [[Roll way]], part of the track of a rubber-tyred metro<ref>{{Cite web |url=http://www.infovisual.info/05/050_en.html |title=runway (roll way) |access-date=7 December 2016 |archive-date=16 June 2016 |archive-url=https://web.archive.org/web/20160616154008/http://infovisual.info/05/050_en.html |url-status=live }}</ref>
* [[Rubber-tyred metro]]
* [[Street running]]
* [[Subgrade]]
* [[Tie plate]]
* [[TGV track construction]]
* [[Tramway (industrial)]]
* [[Tramway track]]
{{div col end}}

==References==
{{Reflist|2}}

== Bibliography ==
* Pike, J., (2001), ''Track'', Sutton Publishing, {{ISBN|0-7509-2692-9}}
* {{cite conference |url=https://link.springer.com/chapter/10.1007/978-3-540-45476-2_21 |title=Simulation of the Dynamic Behavior of Bedding-Foundation-Soil in the Time Domain |last1=Firuziaan |first1=Mohammad |last2=von Estorff |first2=Otto |date=October 2002 |publisher=Springer Verlag |book-title=System Dynamics and Long-Term Behaviour of Railway Vehicles, Track and Subgrade |pages=357–376 |doi=10.1007/978-3-540-45476-2_21 |conference= |isbn=978-3-540-43892-2|url-access=subscription }}
* {{Cite book |last=Robinson |first=A.M. |title=Fatigue in railway infrastructure |publisher=Woodhead Publishing Limited |year=2009 |isbn=978-1-85573-740-2}}
* {{Cite book |last=Lewis |first=R |title=Wheel/rail interface handbook |publisher=Woodhead Publishing Limited |year=2009 |isbn=978-1-84569-412-8}}
* {{cite book |last=Esveld |first=Coenraad |date=2001 |title=Modern Railway Track |location=The Netherlands |publisher=MRT-Productions |isbn=90-800324-3-3}}

==External links==
{{Commons category|Rail tracks}}
* [https://web.archive.org/web/20110707101912/http://www.akrailroad.com/tee-rail-sections-data Table of North American tee rail (flat bottom) sections ]
* [https://web.archive.org/web/20110719025055/http://www.oberbauhandbuch.de/en/oberbauhandbuch/oberbaustoffe/schienen/vignolschienen.html ThyssenKrupp handbook, Vignoles rail]
* [https://web.archive.org/web/20110719025121/http://www.oberbauhandbuch.de/en/oberbauhandbuch/oberbaustoffe/schienen/vignolschienen-feldbahnschienen.html ThyssenKrupp handbook, Light Vignoles rail]
* [http://scalefour.org/resources/trackdetails02.htm Track Details in photographs ]
* [https://books.google.com/books?id=qOIDAAAAMBAJ&pg=PA886 "Drawing of England Track Laying in Sections at 200 yards an hour" ''Popular Mechanics'', December 1930]
*{{citation|chapter-url=http://www.railwaywondersoftheworld.com/permanent-way.html |chapter=The permanent way |title=Railway Wonders of the World |year=1936 |pages = 331–338 |editor-first=Clarence |editor-last=Winchester}} illustrated description of the construction and maintenance of the railway
* [http://www.railway-technical.com/track.shtml Railway technical] {{Webarchive|url=https://web.archive.org/web/20170503184450/http://railway-technical.com/track.shtml |date=3 May 2017 }}

{{Rail tracks}}
{{Railway track layouts}}
{{Authority control}}

[[Category:Permanent way| ]]
[[Category:Railway track layouts]]
[[Category:Structural steel]]
[[Category:Rail infrastructure]]