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The track on a railway or railroad, also known as the permanent way, is the structure consisting of the rails, fasteners, sleepers and ballast (or slab track), plus the underlying subgrade. The term permanent way also refers to the track in addition to lineside structures such as fences etc.
Notwithstanding modern technical developments, the overwhelmingly dominant track form worldwide consists of flat-bottom steel rails supported on timber or pre-stressed concrete sleepers (railroad ties in the US), which are themselves laid on crushed stone ballast.
Most railroads with heavy traffic use continuously welded rails supported by sleepers (ties) attached via baseplates which spread the load. Timber sleepers (ties) are of many available timbers, and are often treated with creosote, copper-chrome-arsenic, or other wood preservative. The track ballast is customarily crushed stone, and the purpose of this is to support the ties and allow some adjustment of their position, while allowing free drainage. 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. There are a number of proprietary systems, and variations include continuous in situ placing of a reinforced concrete slab, or alternatively the use of pre-cast pre-stressed concrete units laid on a base layer. However ballastless track is very expensive in first cost, and in the case of existing railroads requires closure of the route for a somewhat long period. Ladder track utilizes longitudinal sleepers with gauge restraining cross members, it can be considered a development of Baulk road. For much of the 20th century, rail track used softwood timber ties and jointed rails, and considerable extents of this track type remains on secondary and tertiary routes. The technology of rail tracks developed over a long period, starting with primitive timber rails in mines in the 17th century. Hot rolled steel in the profile (cross section) of an asymmetrical I-beam is usually used as the surface on which railway wheels run.[1] 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.
Rails are produced in fixed lengths and need to be joined end-to-end to make a continuous surface on which trains may run.
British practice was to have the rail joints on both rails adjacent to each other, while North American practice is to stagger them. Because of the small gaps left between the rails, when trains pass over jointed tracks they make a "clickety-clack" sound. A major problem of jointed track is cracking around the bolt holes, which can lead to the rail head (the running surface) breaking. As an alternative to the insulated joint, audio frequency track circuits can be employed using a tuned loop formed in approximately 20 m of the rail as part of the blocking circuit. Most modern railways use continuous welded rail (CWR), sometimes referred to as ribbon rails. Flash butt welding is the preferred process which involves an automated track-laying machine running a strong electrical current through the touching ends of two unjoined pieces of rail. 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 different than what is desired. CWR rail is laid (including fastening) at a temperature roughly midway between the extremes experienced at that location (this is known as the "rail neutral temperature"). A railroad tie (also called a cross-tie in North American usage, or a railway sleeper outside North America) is a rectangular object on which the rails are supported and fixed. Sometimes rail tracks are designed to be portable and moved from one place to another as required. On the Panama Canal, tracks were so lifted around as is seen in moving pictures taken of the excavation works.
Cane railways often had permanent tracks for the main lines, with portable tracks serving the canefields themselves. Decauville was a source of many portable light rail tracks, also used for military purposes. The permanent way is so called because temporary way tracks were often used in the construction of that permanent way. During the early days of rail, there was considerable variation in the gauge used by different systems.
Track needs regular maintenance to remain in good order, especially when high-speed trains are involved.
Common maintenance jobs include changing crossties (sleepers), lubricating and adjusting switches, tightening loose track components, and surfacing and lining track to keep straight sections straight and curves within maintenance limits. Spraying ballast with herbicide to prevent weeds growing through and disrupting 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. Rail inspections utilize nondestructive testing methods to detect internal flaws in the rails.
Rails must be replaced before the railhead profile wears to a degree that may trigger a derailment. In the UK, the 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.
Railway tracks are generally laid on a bed of stone track ballast or track bed, in turn is supported by prepared earthworks known as the track formation. Additional measures are required where the track is laid over permafrost, such as on the Qingzang Railway in Tibet. Rail transport in South Africa — is arguably the most important piece of the country s transportation infrastructure. Rail transport in Oregon — Rail transport is an important element of the transportation network in the state of Oregon.
Rail transport in the Philippines — is a growing means of transportation for passengers and cargo in the country. Piece of wood or concrete that is set in ballast and supports the rails to distribute the train’s load and keep the rails parallel. When Structural engineers design steel framed buildings, consideration is given to how to protect the steel frame against corrosion.

So this leads us to the question, why are railway lines, which are also made of steel, left exposed to the elements without any protection at all? It’s a good question and there are a number of reasons.
So to summarise, rails are replaced as a result of wear from use, before they need to be replaced due to metal corrosion.
Grace Nichols: These multimillion dollar projects endanger the clean water of our state which beyond price. For clarity it is often referred to as railway track (British English and UIC terminology) or railroad track (predominantly in the United States).
A plastic or rubber pad is usually placed between the rail and the tieplate where concrete sleepers (ties) are used.
Pre-stressed concrete sleepers (ties) are often used where timber is scarce and where tonnage or speeds are high.
Its whole life cost can be lower because of the great reduction in maintenance requirement. The rails were typically of flat bottom section fastened to the ties with dogspikes through a flat tieplate in North America and Australia, and typically of bullhead section carried in cast iron chairs in British and Irish practice. However the intrinsic weakness in resisting vertical loading results in the ballast support becoming depressed and a heavy maintenance workload is imposed to prevent unacceptable geometrical defects at the joints. It took many decades to improve the quality of the materials, including the change from iron to steel. Heavier rail can support greater axle loads and higher train speeds without sustaining damage than lighter rail, but at a greater cost. The traditional method of joining the rails is to bolt them together using metal fishplates, producing jointed track. Note how bolts are oppositely oriented to prevent complete separation of the joint in the event of being struck by a wheel during a derailment.
The bolts may be oppositely-oriented 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 exacerbating the seriousness of the derailment. Unless it is well-maintained, jointed track does not have the ride quality of welded rail and is less desirable for high speed trains.
This was the cause of the Hither Green rail crash which caused British Railways to begin converting much of its track to Continuous Welded Rail. Another alternative is the axle counter, which can reduce the number of track circuits and thus the number of insulated rail joints required.
In this form of track, the rails are welded together by utilising flash butt welding to form one continuous rail that may be several kilometres long, or thermite welding to repair or splice together existing CWR segments. The ends become white hot due to electrical resistance and are then pressed together forming a strong weld.
To provide this restraint, the rail is prevented from moving in relation to the sleeper by use of clips or anchors. The stressing process involves either heating the rails causing them to expand,[6] or stretching the rails with hydraulic equipment.
This installation procedure, along with normal track structure strength, is intended to prevent tracks from buckling in summer heat or pulling apart in winter cold. 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. The tie 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). Historically spikes gave way to cast iron chairs fixed to the sleeper, more recently springs (such as Pandrol clips) are used to fix the rail to the sleeper chair.
Inadequate maintenance may lead to a "slow order" (North American terminology, a "slack" or speed restriction in the United Kingdom) being imposed to avoid accidents (see Slow zone). If this is not done, the tracks may become uneven causing swaying, rough riding and possibly derailments.
This is done by using specially equipped HiRail trucks, inspection cars, or in some cases handheld inspection devices. Worn mainline rails usually have sufficient life to be used on a branch line, siding or stub afterwards and are "cascaded" to those applications. 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 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.
The formation comprises the 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. For example, transverse pipes through the subgrade allow cold air to penetrate the formation and prevent that subgrade from melting. Rubber sheets may be inserted to help drainage and also protect iron bridgework from being affected by rust.
The Australian rail network consists of a total of 33,819 km of track of three major gauges, of which 2,540 km is electrified. All major cities are connected by rail, and South Africa s railway system is the most highly developed in Africa. Such means of transportation are used typically used for rapid transport within major cites as well as long distance travel.
Various measures can be employed, but the typical solution is to coat the steel frame with anti-corrosion paint, and a primer, while steel exposed to moisture or within the wall cavity will be specified as stainless steel. Compared with the steel used for buildings, the steel in a rail is composed of a higher quality steel alloy, which is less susceptible to corrosion. The top and upper side face of a rail doesn’t usually corrode because friction and wear keep it polished and free of rust.
Anti-corrosion coatings are not applied to steel rail lines as the coating would hide any developing fractures or defects. Corrosion isn’t an issue because it has less of an impact on the relatively massive rail section, when compared to say the thin sheets of steel used in the body of a car.
It’s just that the rate of corrosion is relatively much slower than the wear and tear.

The rail is usually held down to the sleeper (tie) with resilient fastenings, although cut spikes are widely used in North American practice.
Ballastless track is usually considered for new very high speed or very high loading routes, in short extensions that require additional strength (i.e. The joints also required to be lubricated, and wear at the fishplate (joint bar) mating surfaces needed to be rectified by shimming. The heavier the rails and the rest of the trackwork, the heavier and faster the trains the track can carry. For more modern usage, particularly where higher speeds are required, the lengths of rail may be welded together to form continuous welded rail (CWR). However, jointed track is still used in many countries on lower speed lines and sidings, and is used extensively in poorer countries due to the lower construction cost and the simpler equipment required for its installation and maintenance.
Specially-made glued joints, where all the gaps are filled with epoxy resin, increase the strength again. 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. Thermite welding is a manual process requiring a reaction crucible and form to contain the molten iron. Anchors are more common for wooden sleepers, whereas most concrete or steel sleepers are fastened to the rail by special clips which resist longitudinal movement of the rail. In North America, because broken rails are typically detected by the signaling system; they are seen as less of a problem than heat kinks which are not detected.
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 wheel while allowing the end of one rail to expand in relation to the next rail.
An alternative to tamping is to lift the rails and sleepers and reinsert the ballast beneath. This type of steel is much more expensive and slightly weaker but it is corrosion resistant. This is necessary as the rail will be subjected to much higher dynamic stresses than the steel in a building frame. The rail company also grind the track to remove surface imperfections caused by the trains braking, if these imperfections were allowed to worsen and deepen, the high impact force of the train hitting them at high speed could cause the rail to fracture.
Cracking of tracks from metal fatigue is taken very seriously and regular inspections are carried out to check for defects.
It is also slowed by the quality of the steel used in the rail and by the protective layer of rust that develops initially.
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).
For this reason jointed track is not financially appropriate for heavily operated railroads. The holes through which the fishplate bolts pass are oval to allow for movement with expansion. Welded rails are more expensive to lay than jointed tracks, but have much lower maintenance costs. Sometimes coatings are applied but only in very rare cases where the track will be used in very severe conditions, for instance as in India where a freight line for carrying salt ore needed to be protected from the corrosive salt falling on to the line. Rails used on a curved section of track are subjected to much higher wear than rails on straight sections. The first welded track was used in Germany in 1924 and the US in 1930[5] and has become common on main lines since the 1950s. However, if longitudinal and lateral restraint are insufficient, the track could become distorted in hot weather and cause a derailment.
In cold weather the rails try to contract, but because they are firmly fastened, cannot do so.
When the rust forms on the face of the rail it acts as a barrier which then slows the rate of corrosion. In general rails on heavily used section of track could be replaced every 15 to 20 years, with wear being the reason for replacement rather than corrosion. Distortion due to heat expansion is known in North America as sun kink, and elsewhere as buckling. In effect, stressed rails are a bit like a piece of stretched elastic firmly fastened down. A typical steel beam used in a building might be only 6mm at its narrowest point, while a steel rail will be about 15mm wide at its narrowest point. The rails are usually taken up and reused in shunting yards or lightly trafficked sections of track where they would be subjected to less stress. 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. In extreme hot weather special inspections are required to monitor sections of track known to be problematic. It will therefore take 20 years for 1mm of steel to be compromised by rust from each face, or 2mm if both sides are exposed. If the unprotected steel section is 6mm wide one third of the section will be compromised in the 20 years, but a steel rail would only have approx 15% of its section compromised. In practice it will be less than this as the steel in the rail is more corrosion resistant.
Therefore for a rail section the loss of strength from corrosion is probably negligible as compared with the loss from friction and wear from the train wheels.

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  • STRIKE, 08.09.2013 at 15:50:53
    Australia has been a cottage-market affair tracks so that trains can stop there one which failed to survived.