Editing Rail transport (section)

==Infrastructure==
[[File:World railway network.svg|thumb|350x350px|Map of world railway network as of 2022]]

===Right-of-way===
{{Main|Right-of-way (property access)}}
Railway tracks are laid upon land owned or leased by the railway company. Owing to the desirability of maintaining modest grades, in hilly or mountainous terrain rails will often be laid in circuitous routes . Route length and grade requirements can be reduced by the use of alternating [[cutting (transportation)|cuttings]], bridges and tunnels&nbsp;– all of which can greatly increase the capital expenditures required to develop a right-of-way, while significantly reducing operating costs and allowing higher speeds on longer radius curves. In densely urbanised areas, railways are sometimes laid in tunnels to minimise the effects on existing properties.

===Track===
{{Main|Track (rail transport)|l1=Track}}{{multiple image
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| footer            = Left: Railway turnouts; Right: [[Chicago Transit Authority]] control box guides elevated [[Chicago 'L']] north and southbound [[Purple Line (Chicago Transit Authority)|Purple]] and [[Brown Line (Chicago Transit Authority)|Brown]] lines [[Diamond crossing|intersecting]] with east and westbound [[Pink Line (Chicago Transit Authority)|Pink]] and [[Green Line (Chicago Transit Authority)|Green]] lines and the looping [[Orange Line (Chicago Transit Authority)|Orange line]] above the [[Wells Street (Chicago)|Wells]] and [[Lake Street (Chicago)|Lake street]] [[intersection (road)|intersection]] in the [[Loop (CTA)|loop]] at an [[Elevated railway|elevated]] [[Right-of-way (transportation)|right of way]].
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| image1            = Pöörangud Tartu raudteejaamas.jpg
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Track consists of two parallel steel rails, anchored [[perpendicular]] to members called [[railroad tie|sleepers]] (ties) of timber, concrete, steel, or plastic to maintain a consistent distance apart, or [[rail gauge]]. Other variations are also possible, such as "slab track", in which the rails are fastened to a concrete foundation resting on a prepared subsurface.

Rail gauges are usually categorized as [[standard gauge]] (used on approximately 70% of the world's existing railway lines), [[broad gauge]], and [[narrow gauge]].<ref>{{Cite book |last=Rodrigue |first=Jean-Paul |url=https://www.worldcat.org/oclc/1133662497 |title=The geography of transport systems |date=2020 |isbn=978-0-429-34632-3 |edition=Fifth |publisher=Routledge |location=Abingdon, Oxon |oclc=1133662497}}</ref> In addition to the rail gauge, the tracks will be laid to conform with a [[loading gauge]] which defines the maximum height and width for railway vehicles and their loads to ensure safe passage through bridges, tunnels and other structures.

The track guides the conical, flanged wheels, keeping the cars on the track without active steering and therefore allowing trains to be much longer than road vehicles. The rails and ties are usually placed on a foundation made of compressed earth on top of which is placed a bed of [[track ballast|ballast]] to distribute the load from the ties and to prevent the track from [[buckling]] as the ground settles over time under the weight of the vehicles passing above.

The ballast also serves as a means of drainage. Some more modern track in special areas is attached directly without ballast. Track may be prefabricated or assembled in place. By [[Thermite welding|welding]] rails together to form lengths of [[continuous welded rail]], additional wear and tear on rolling stock caused by the small surface gap at the joints between rails can be counteracted; this also makes for a quieter ride.

On curves, the outer rail may be at a higher level than the inner rail. This is called superelevation or [[cant (road/rail)|cant]]. This reduces the forces tending to displace the track and makes for a more comfortable ride for standing livestock and standing or seated passengers. A given amount of superelevation is most effective over a limited range of speeds.

Points and switches{{Mdash}}also known as [[Railroad switch|turnouts]]{{Mdash}}are the means of directing a train onto a diverging section of track. Laid similar to normal track, a point typically consists of a [[Switch frog|frog]] (common crossing), check rails and two switch rails. The switch rails may be moved left or right, under the control of the signalling system, to determine which path the train will follow.

Spikes in wooden ties can loosen over time, but split and rotten ties may be individually replaced with new wooden ties or concrete substitutes. Concrete ties can also develop cracks or splits, and can also be replaced individually. Should the rails settle due to soil subsidence, they can be lifted by specialized machinery and additional ballast tamped under the ties to level the rails.

Periodically, ballast must be removed and replaced with clean ballast to ensure adequate drainage. Culverts and other passages for water must be kept clear lest water is impounded by the trackbed, causing landslips. Where trackbeds are placed along rivers, additional protection is usually placed to prevent streambank erosion during times of high water. Bridges require inspection and maintenance, since they are subject to large surges of stress in a short period of time when a heavy train crosses.

===Gauge incompatibility===
{{Main|Break of gauge}}
The use of different [[track gauge]]s in different regions of the world, and sometimes within the same country, can impede the movement of passengers and freight. Often elaborate transfer mechanisms are installed where two lines of different gauge meet to facilitate movement across the [[break of gauge]]. Countries with multiple gauges in use, such as [[Project Unigauge|India]] and [[Rail gauge in Australia|Australia]], have invested heavily to unify their rail networks. China is developing a modernized [[Eurasian Land Bridge]] to move goods by rail to Western Europe.

===Train inspection systems===
{{Main|Train inspection system}}
[[File:HBD DD1.jpg|thumb|A [[Defect detector#Sensors|dragging equipment unit]] with [[Hot box|hot bearing detector]]]]

The inspection of railway equipment is essential for the safe movement of trains. Many types of [[defect detector]]s are in use on the world's railroads. These devices use technologies that vary from a simplistic paddle and switch to [[infrared]] and laser scanning, and even [[ultrasonic testing|ultrasonic audio analysis]]. Their use has avoided many rail accidents over the 70 years they have been used.

===Signalling===
[[File:LeicesterAndSwannington02A.jpg|right|thumb|[[Bardon Hill]] box in [[England]] (seen here in 2009) is a [[Midland Railway]] box dating from 1899, although the original mechanical lever frame has been replaced by electrical switches.]]
{{Main|Railway signalling}}
[[Railway signalling]] is a system used to control railway traffic safely to prevent trains from colliding. Being guided by fixed [[track (rail transport)|rails]] which generate low friction, trains are uniquely susceptible to collision since they frequently operate at speeds that do not enable them to stop quickly or within the driver's sighting distance; road vehicles, which encounter a higher level of friction between their rubber tyres and the road surface, have much shorter braking distances. Most forms of train control involve movement authority being passed from those responsible for each section of a rail network to the train crew. Not all methods require the use of signals, and some systems are specific to [[single track (rail)|single track]] railways.

The signalling process is traditionally carried out in a [[signal box]], a small building that houses the [[lever frame]] required for the signalman to operate switches and signal equipment. These are placed at various intervals along the route of a railway, controlling specified sections of track. More recent technological developments have made such operational doctrine superfluous, with the centralization of signalling operations to regional control rooms. This has been facilitated by the increased use of computers, allowing vast sections of track to be monitored from a single location. The common method of [[Railway signalling#Blocks|block signalling]] divides the track into zones guarded by combinations of block signals, operating rules, and automatic-control devices so that only one train may be in a block at any time.

===Electrification===
{{Main|Railway electrification system}}
The electrification system provides electrical energy to the trains, so they can operate without a prime mover on board. This allows lower operating costs, but requires large capital investments along the lines. Mainline and tram systems normally have overhead wires, which hang from poles along the line. Grade-separated rapid transit sometimes use a ground [[third rail]].

Power may be fed as [[direct current|direct]] (DC) or [[alternating current]] (AC). The most common DC voltages are 600 and 750&nbsp;V for tram and rapid transit systems, and 1,500&nbsp;and 3,000&nbsp;V for mainlines. The two dominant AC systems are [[15 kV AC railway electrification|15&nbsp;kV]] and [[25 kV AC railway electrification|25&nbsp;kV]].

===Stations===
{{Main|Train station}}
[[File:Rang gueter bahnhof small.jpg|thumb|upright=1.15|Goods station in [[Lucerne]], Switzerland]]A [[railway station]] serves as an area where passengers can board and alight from trains. A [[goods station]] is a yard which is exclusively used for loading and unloading cargo. Large passenger stations have at least one building providing conveniences for passengers, such as purchasing tickets and food. Smaller stations typically only consist of a [[railway platform|platform]]. Early stations were sometimes built with both passenger and goods facilities.<ref>{{cite journal| title=The Inception of the English Railway Station| journal=[[Architectural History (journal)|Architectural History]]| volume=4| year=1961| pages=63–76| doi=10.2307/1568245| jstor=1568245| s2cid=246043093}}</ref>

Platforms are used to allow easy access to the trains, and are connected to each other via [[underpass]]es, [[footbridge]]s and [[level crossing]]s. Some large stations are built as [[cul-de-sac|culs-de-sac]], with trains only operating out from one direction. Smaller stations normally serve local residential areas, and may have connection to feeder bus services. Large stations, in particular [[central station]]s, serve as the main [[transport hub|public transport hub]] for the city, and have transfer available between rail services, and to rapid transit, tram or bus services.