85-419: The track bed or trackbed is the groundwork onto which a railway track is laid. Trackbeds of disused railways are sometimes used for recreational paths or new light rail links. According to Network Rail , the trackbed is the layers of ballast and sub-ballast above a prepared subgrade /formation (see diagram). It is designed primarily to reduce the stress on the subgrade. Other definitions include
170-502: A slipformed (or pre-cast) concrete base (development 2000s). The 'embedded rail structure', used in the Netherlands since 1976, initially used a conventional UIC 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). Modern ladder track can be considered
255-589: A train track or permanent way (often " perway " in Australia or " P Way " in Britain and India), is the structure on a railway or railroad consisting of the rails , fasteners , railroad ties (sleepers, British English) and ballast (or slab track ), plus the underlying subgrade . It enables trains to move by providing a dependable surface for their wheels to roll upon. Early tracks were constructed with wooden or cast iron rails, and wooden or stone sleepers; since
340-440: A "clickety-clack" sound. Unless it is well-maintained, jointed track does not have the ride quality of welded rail and is less desirable for high speed trains . 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. A major problem of jointed track
425-423: A 180 mm (7.1 in) lip to form the flange. The buses run on normal road wheels with side-mounted guidewheels to run against the flanges. Buses are steered normally when off the busway, analogous to the 18th-century wagons which could be manoeuvered around pitheads before joining the track for the longer haul. Bridge rail is a rail with an inverted-U profile. Its simple shape is easy to manufacture, and it
510-412: A bumpy ride for the passengers, damage to either wheel or rail and possibly derailing . The traditional form of grooved rail is the girder guard section illustrated to the left. This rail is a modified form of flanged rail and requires a special mounting for weight transfer and gauge stabilisation. If the weight is carried by the roadway subsurface, steel ties are needed at regular intervals to maintain
595-425: A change. Cylindrical wheel treads have to "skid" on track curves so increase both drag and rail and wheel wear. On very straight track a cylindrical wheel tread rolls more freely and does not "hunt". The gauge is narrowed slightly and the flange fillets keep the flanges from rubbing the rails. United States practice is a 1 in 20 cone when new. As the tread wears it approaches an unevenly cylindrical tread, at which time
680-415: 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
765-407: A cross section (profile) approximate to an I-beam , but asymmetric about a horizontal axis (however see grooved rail below). The head is profiled to resist wear and to give a good ride, and the foot profiled to suit the fixing system. Unlike some other uses of iron and steel, railway rails are subject to very high stresses and are made of very high quality steel. It took many decades to improve
850-481: 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. Modern track typically uses hot-rolled steel with a profile of an asymmetrical rounded I-beam . 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
935-472: A much quieter ride than stone blocks and it was possible to fasten the rails directly using clips or rail spikes . Their use, and Vignoles's name, spread worldwide. The joint where the ends of two rails are connected to each other is the weakest part of a rail line. The earliest iron rails were joined by a simple fishplate or bar of metal bolted through the web of the rail. Stronger methods of joining two rails together have been developed. When sufficient metal
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#17330849002521020-416: A nuisance to other road users, except unsuspecting cyclists , who could get their wheels caught in the groove. The grooves may become filled with gravel and dirt (particularly if infrequently used or after a period of idleness) and need clearing from time to time, this being done by a "scrubber" vehicle (either a specialised tram, or a maintenance road-rail vehicle ). Failure to clear the grooves can lead to
1105-500: A prize for the best design, and was one of the earliest lines to use double-headed rail, where the head and foot of the rail had the same profile. These rails were supported by chairs fastened to the sleepers. The advantage of double-headed rails was that, when the rail head became worn, they could be turned over and re-used. In 1835 Peter Barlow of the London and Birmingham Railway expressed concern that this would not be successful because
1190-626: A railroad. There were no steel mills in America capable of rolling long lengths, so he sailed to the United Kingdom which was the only place where his flanged T rail (also called T-section) could be rolled. Railways in the UK had been using rolled rail of other cross-sections which the ironmasters had produced. In May 1831, the first 500 rails, each 15 feet (4.6 m) long and weighing 36 pounds per yard (17.9 kg/m), reached Philadelphia and were placed in
1275-624: A smaller cross-section than the Stevens rail, with a wider base than modern rail, fastened with screws through the base. Other lines which adopted it were the Hull and Selby , the Newcastle and North Shields , and the Manchester, Bolton and Bury Canal Navigation and Railway Company. When it became possible to preserve wooden sleepers with mercuric chloride (a process called Kyanising ) and creosote , they gave
1360-465: A temperature roughly midway between the extremes experienced at that location. (This is known as the "rail neutral temperature".) 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. Joints are used in
1445-462: Is 115 to 141 lb/yd (57 to 70 kg/m). In Europe, rail is graded in kilograms per metre and the usual range is 40 to 60 kg/m (81 to 121 lb/yd). The heaviest mass-produced rail was 155 pounds per yard (77 kg/m), rolled for the Pennsylvania Railroad . The rails used in rail transport are produced in sections of fixed length. Rail lengths are made as long as possible, as
1530-408: Is a manual process requiring a reaction crucible and form to contain the molten iron. North American practice is to weld 1 ⁄ 4 -mile-long (400 m) 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
1615-886: Is a much stronger material, which steadily replaced iron for use on railway rail and allowed much longer lengths of rails to be rolled. The American Railway Engineering Association (AREA) and the American Society for Testing Materials (ASTM) specified carbon, manganese, silicon and phosphorus content for steel rails. Tensile strength increases with carbon content, while ductility decreases. AREA and ASTM specified 0.55 to 0.77 percent carbon in 70-to-90-pound-per-yard (34.7 to 44.6 kg/m) rail, 0.67 to 0.80 percent in rail weights from 90 to 120 lb/yd (44.6 to 59.5 kg/m), and 0.69 to 0.82 percent for heavier rails. Manganese increases strength and resistance to abrasion. AREA and ASTM specified 0.6 to 0.9 percent manganese in 70 to 90 pound rail and 0.7 to 1 percent in heavier rails. Silicon
1700-488: 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 Railways to begin converting much of its track to continuous welded rail. Where track circuits exist for signalling purposes, insulated block joints are required. These compound the weaknesses of ordinary joints. Specially-made glued joints, where all
1785-539: Is for lower speed freight branch lines or rapid transit ; for example, most of the New York City Subway system track is constructed with 100 lb/yd (49.6 kg/m) rail. Main line track is usually built with 130 lb/yd (64.5 kg/m) rail or heavier. Some common North American rail sizes include: Some common North American crane rail sizes include: Some common Australian rail sizes include: Advances in rail lengths produced by rolling mills include
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#17330849002521870-402: 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 130 lb/yd (64 kg/m). The usual range
1955-424: Is preferentially oxidised by oxygen and is added to reduce the formation of weakening metal oxides in the rail rolling and casting procedures. AREA and ASTM specified 0.1 to 0.23 percent silicon. Phosphorus and sulfur are impurities causing brittle rail with reduced impact-resistance. AREA and ASTM specified maximum phosphorus concentration of 0.04 percent. The use of welded rather than jointed track began in around
2040-468: Is put into the rail joint, the joint is almost as strong as the rest of the rail length. The noise generated by trains passing over the rail joints, described as "the clickity clack of the railroad track", can be eliminated by welding the rail sections together. Continuously welded rail has a uniform top profile even at the joints. In late 1830s, Britain's railways used a range of different rail patterns. The London and Birmingham Railway , which had offered
2125-558: Is required in the combined section. A modern block rail with a further reduction in mass is the LR55 rail which is polyurethane grouted into a prefabricated concrete beam. It can be set in trench grooves cut into an existing asphalt road bed for Light Rail (trams). The weight of a rail per length is an important factor in determining rail strength and hence axleloads and speeds. Weights are measured in pounds per yard ( imperial units in Canada,
2210-402: Is scarce and where tonnage or speeds are high. Steel is used in some applications. The track ballast is customarily crushed stone, and the purpose of this is to support the sleepers 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
2295-456: Is starting to paint rails white to lower the peak temperatures reached in summer days. 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 stressing process involves either heating the rails, causing them to expand, or stretching the rails with hydraulic equipment. They are then fastened (clipped) to
2380-454: Is the popular name for flat-bottomed rail, recognising engineer Charles Vignoles who introduced it to Britain . Charles Vignoles observed that wear was occurring with wrought iron rails and cast iron chairs on stone blocks, the most common system at that time. In 1836 he recommended flat-bottomed rail to the London and Croydon Railway for which he was consulting engineer. His original rail had
2465-518: Is then known as grooved rail , groove rail , or girder rail . The flangeway has the railhead on one side and the guard on the other. The guard carries no weight, but may act as a checkrail. Grooved rail was invented in 1852 by Alphonse Loubat , a French inventor who developed improvements in tram and rail equipment, and helped develop tram lines in New York City and Paris. The invention of grooved rail enabled tramways to be laid without causing
2550-754: Is to bolt them together using metal fishplates (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 is made using lengths of rail, usually around 20 m (66 ft) long (in the UK) and 39 or 78 ft (12 or 24 m) long (in North America), bolted together using perforated steel plates known as fishplates (UK) or joint bars (North America). Fishplates are usually 600 mm (2 ft) long, used in pairs either side of
2635-435: 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. Early railways (c. 1840s) experimented with continuous bearing railtrack, in which
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2720-484: The Butterley Company . The earliest of these in general use were the so-called cast iron fishbelly rails from their shape. Rails made from cast iron were brittle and broke easily. They could only be made in short lengths which would soon become uneven. John Birkinshaw 's 1820 patent, as rolling techniques improved, introduced wrought iron in longer lengths, replaced cast iron and contributed significantly to
2805-557: The First World War . Bullhead rail was developed from double-headed rail. The profile of the head of the rail is not the same as the foot. Because it does not have a symmetrical profile, it was not possible to reverse bullhead rail over and use the foot as the head. It was an expensive method of laying track as heavy cast iron chairs were needed to support the rail, which was secured in the chairs by wooden (later steel) wedges or "keys", which required regular attention. Bullhead rail
2890-573: The 1870s, rails have almost universally been made from steel. 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 around 50 wooden-railed tramways built over the next 164 years. 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
2975-528: The 1924 standard as "R.B.S." (Revised). Bullhead rail has been almost completely replaced by flat-bottom rail on the British rail system, although it survives on some branch lines and sidings . It can also be found on heritage railways , due both to the desire to maintain an historic appearance, and the use of old track components salvaged from main lines. The London Underground continued to use bullhead rail after it had been phased out elsewhere in Britain but, in
3060-448: The 1940s and had become widespread by the 1960s. The earliest rails were simply lengths of timber. To resist wear, a thin iron strap was laid on top of the timber rail. This saved money as wood was cheaper than metal. The system had the flaw that every so often the passage of the wheels on the train would cause the strap to break away from the timber. The problem was first reported by Richard Trevithick in 1802. The use of strap rails in
3145-404: The United Kingdom and United States) and kilograms per metre in mainland Europe and Australia ). 1 kg/m = 2.0159 lb/yd. Commonly, in rail terminology pound is a metonym for the expression pounds per yard and hence a 132–pound rail means a rail of 132 pounds per yard. Rails are made in a large number of different sizes. Some common European rail sizes include: In
3230-519: The United States (for instance on the Albany and Schenectady Railroad c. 1837) led to passengers being threatened by "snake-heads" when the straps curled up and penetrated the carriages. T-rail was a development of strap rail which had a 'T' cross-section formed by widening the top of the strap into a head. This form of rail was generally short-lived, being phased out in America by 1855. Plate rail
3315-400: The bolt heads on the same side of the rail. Small gaps which function as expansion joints 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, while North American practice is to stagger them. Because of these small gaps, when trains pass over jointed tracks they make
3400-444: The canefields themselves. These tracks were narrow gauge (for example, 2 ft ( 610 mm )) and the portable track came in straights, curves, and turnouts, rather like on a model railway. Rail profile#Bullhead rail The rail profile is the cross sectional shape of a railway rail , perpendicular to its length. Early rails were made of wood, cast iron or wrought iron. All modern rails are hot rolled steel with
3485-458: 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
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3570-425: The cost of a railway line. Only a small number of rail sizes are made by steelworks at one time, so a railway must choose the nearest suitable size. Worn, heavy rail from a mainline is often reclaimed and downgraded for re-use on a branch line , siding or yard . The earliest rails used on horse-drawn wagonways were wooden,. In the 1760s strap-iron rails were introduced with thin strips of cast iron fixed onto
3655-656: The countries of the former USSR , 65 kg/m (131 lb/yd) rails and 75 kg/m (151 lb/yd) rails (not thermally hardened) are common. Thermally hardened 75 kg/m (151 lb/yd) rails also have been used on heavy-duty railroads like Baikal–Amur Mainline , but have proven themselves deficient in operation and were mainly rejected in favor of 65 kg/m (131 lb/yd) rails. The American Society of Civil Engineers (or ASCE) specified rail profiles in 1893 for 5 lb/yd (2.5 kg/m) increments from 40 to 100 lb/yd (19.8 to 49.6 kg/m). Height of rail equaled width of foot for each ASCE tee-rail weight; and
3740-440: 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
3825-440: The end of one rail to expand relative to the next rail. 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. Various methods exist for fixing
3910-718: The explosive growth of railroads in the period 1825–40. The cross-section varied widely from one line to another, but were of three basic types as shown in the diagram. The parallel cross-section which developed in later years was referred to as bullhead . Meanwhile, in May 1831, the first flanged T rail (also called T-section) arrived in America from Britain and was laid into the Pennsylvania Railroad by Camden and Amboy Railroad . They were also used by Charles Vignoles in Britain. The first steel rails were made in 1857 by Robert Forester Mushet , who laid them at Derby station in England. Steel
3995-426: The following: Welding of rails into longer lengths was first introduced around 1893. Welding can be done in a central depot or in the field. It has long been recognised that conical wheels and rails that are sloped by the same amount follow curves better than cylindrical wheels and vertical rails. A few railways such as Queensland Railways for a long time had cylindrical wheels until much heavier traffic required
4080-428: The gaps are filled with epoxy resin , increase the strength again. As an alternative to the insulated joint, audio frequency track circuits can be employed using a tuned loop formed in approximately 20 m (66 ft) 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
4165-409: The gauge. Installing these means that the whole surface needs to be excavated and reinstated. Block rail is a lower profile form of girder guard rail with the web eliminated. In profile it is more like a solid form of bridge rail, with a flangeway and guard added. Simply removing the web and combining the head section directly with the foot section would result in a weak rail, so additional thickness
4250-770: The head. AREA recommended the ARA 90 lb/yd (44.6 kg/m) profile. Old ASCE rails of lighter weight remained in use, and satisfied the limited demand for light rail for a few decades. AREA merged into the American Railway Engineering and Maintenance-of-Way Association in 1997. By the mid-20th century, most rail production was medium heavy (112 to 119 lb/yd or 55.6 to 59.0 kg/m) and heavy (127 to 140 lb/yd or 63.0 to 69.4 kg/m). Sizes under 100 lb/yd (49.6 kg/m) rail are usually for lighter duty freight, low use trackage, or light rail . Track using 100 to 120 lb/yd (49.6 to 59.5 kg/m) rail
4335-595: The initial savings in construction costs. Cast-iron rails with vertical flanges were introduced by Benjamin Outram of B. Outram & Co. which later became the Butterley Company in Ripley. The wagons that ran on these plateway rails had a flat profile. Outram's partner William Jessop preferred the use of " edge rails " where the wheels were flanged and the rail heads were flat - this configuration proved superior to plateways. Jessop's (fishbellied) first edge rails were cast by
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#17330849002524420-626: 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
4505-474: The iron came loose, began to curl, and intruded into the floors of the coaches. The iron strap rail coming through the floors of the coaches came to be referred to as "snake heads" by early railroaders. 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. Rail
4590-402: The joints between rails are a source of weakness. Throughout the history of rail production, lengths have increased as manufacturing processes have improved. The following are lengths of single sections produced by steel mills , without any thermite welding . Shorter rails may be welded with flashbutt welding , but the following rail lengths are unwelded. Welding of rails into longer lengths
4675-405: The last few years, there has been a concerted effort to replace it with flat-bottom rail. However, the process of replacing track in tunnels is a slow one, due to the difficulty of using heavy plant and machinery. Where a rail is laid in a road surface (pavement) or within grassed surfaces, there has to be accommodation for the flange. This is provided by a slot called the flangeway. The rail
4760-863: The mid- to late-20th century used rails 39 feet (11.9 m) long so they could be carried in gondola cars ( open wagons ), often 40 feet (12.2 m) 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. Early North American railroads used iron on top of wooden rails as an economy measure but gave up this method of construction after
4845-620: The number of insulated rail joints required. Most modern railways use continuous welded rail (CWR), sometimes referred to as ribbon rails or seamless rails . 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. 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
4930-404: The outside of sharp curves compared to the rails on the inside. 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. 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
5015-812: The profiles specified fixed proportion of weight in head, web and foot of 42%, 21% and 37%, respectively. ASCE 90 lb/yd (44.6 kg/m) profile was adequate; but heavier weights were less satisfactory. In 1909, the American Railway Association (or ARA) specified standard profiles for 10 lb/yd (4.96 kg/m) increments from 60 to 100 lb/yd (29.8 to 49.6 kg/m). The American Railway Engineering Association (or AREA) specified standard profiles for 100 lb/yd (49.6 kg/m), 110 lb/yd (54.6 kg/m) and 120 lb/yd (59.5 kg/m) rails in 1919, for 130 lb/yd (64.5 kg/m) and 140 lb/yd (69.4 kg/m) rails in 1920, and for 150 lb/yd (74.4 kg/m) rails in 1924. The trend
5100-399: The quality of the materials, including the change from iron to steel. Minor flaws in the steel that may pose no problems in other applications can lead to broken rails and dangerous derailments when used on railway tracks. By and large, the heavier the rails and the rest of the track work, the heavier and faster the trains these tracks can carry. Rails represent a substantial fraction of
5185-423: 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. Other profiles of rail include: bullhead rail ; grooved rail ; flat-bottomed rail (Vignoles rail or flanged T-rail); bridge rail (inverted U–shaped used in baulk road ); and Barlow rail (inverted V). North American railroads until
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#17330849002525270-682: 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. The German railway company Deutsche Bahn
5355-425: The rail ends and bolted together (usually four, but sometimes six 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 exacerbating the derailment. This technique is not applied universally; European practice being to have all
5440-494: The rail to the sleeper. 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. 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 5 ft ( 1,524 mm ) and
5525-579: 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 , on the Lancashire and Yorkshire Railway to a design by John Hawkshaw , and elsewhere. Continuous-bearing designs were also promoted by other engineers. The system was tested on the Baltimore and Ohio railway in the 1840s, but
5610-549: 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 ancient obelisk in Central Park to its final location from the dock where it was unloaded from the cargo ship SS Dessoug . Cane railways often had permanent tracks for the main lines, with portable tracks serving
5695-426: 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 elastic firmly fastened down. In extremely cold weather, rails are heated to prevent "pull aparts". CWR is laid (including fastening) at
5780-603: 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 3 feet (0.91 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. The first iron rails laid in Britain were at the Darby Ironworks in Coalbrookdale in 1767. When steam locomotives were introduced, starting in 1804,
5865-540: 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 spikes 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, flat-bottomed rails were typically fastened to
5950-428: The sleepers with dog spikes through a flat tie plate. In Britain and Ireland, 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. Jointed rails were used at first because contemporary technology did not offer any alternative. However,
6035-652: The supporting chair would cause indentations in the lower surface of the rail, making it unsuitable as the running surface. Although the Great Northern Railway did experience this problem, double-headed rails were successfully used and turned by the London and South Western Railway , the North Eastern Railway , the London, Brighton and South Coast Railway and the South Eastern Railway . Double-headed rails continued in widespread use in Britain until
6120-461: The surface of the ballast on which the track is laid, the area left after a track has been dismantled and the ballast removed or the track formation beneath the ballast and above the natural ground. The trackbed can significantly influence the performance of the track, especially ride quality of passenger services. Rail tracks A railway track ( British English and UIC terminology ) or railroad track ( American English ), also known as
6205-511: The ties (sleepers) in a continuous operation. 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
6290-406: The top of the wooden rails. This increased the durability of the rails. Both wooden and strap-iron rails were relatively inexpensive, but could only carry a limited weight. The metal strips of strap-iron rails sometimes separated from the wooden base and speared into the floor of the carriages above, creating what was referred to as a "snake head". The long-term maintenance expense involved outweighed
6375-406: The track then in use proved too weak to carry the additional weight. Richard Trevithick 's pioneering locomotive at 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
6460-475: The track, marking the first use of the flanged T rail. Afterwards, the flanged T rail became employed by all railroads in the United States. Col. Stevens also invented the hooked spike for attaching the rail to the crosstie (or sleeper). In 1860, the screw spike was introduced in France where it was widely used. Screw spikes are the most common form of spike in use worldwide in the 21st century. Vignoles rail
6545-576: Was an early type of rail and had an 'L' cross-section in which the flange kept an unflanged wheel on the track. The flanged rail has seen a minor revival in the 1950s, as guide bars , with the Paris Métro ( Rubber-tyred metro or French Métro sur pneus ) and more recently as the Guided bus . In the Cambridgeshire Guided Busway the rail is a 350 mm (14 in) thick concrete beam with
6630-587: Was difficult to keep it in gauge. Flat bottomed rail is the dominant rail profile in worldwide use. Flanged T rail (also called T-section) is the name for flat bottomed rail used in North America . Iron-strapped wooden rails were used on all American railways until 1831. Col. Robert L. Stevens , the President of the Camden and Amboy Railroad , conceived the idea that an all-iron rail would be better suited for building
6715-467: 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. Modern production techniques allowed the production of longer unwelded segments. Newer longer rails tend to be made as simple multiples of older shorter rails, so that old rails can be replaced without cutting. Some cutting would be needed as slightly longer rails are needed on
6800-432: Was found to be more expensive to maintain than rail with cross sleepers . 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. Later applications of continuously supported track include Balfour Beatty 's 'embedded slab track', which uses a rounded rectangular rail profile (BB14072) embedded in
6885-466: Was soon replaced with flexible track structures that allowed a degree of elastic movement as trains passed over them. 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 ballast placed beneath and around the sleepers. Most modern railroads with heavy traffic use continuously welded rails that are attached to
6970-451: Was the standard for the British railway system from the mid-19th until the mid-20th century. In 1954, bullhead rail was used on 449 miles (723 km) of new track and flat-bottom rail on 923 miles (1,485 km). One of the first British Standards , BS 9, was for bullhead rail - it was originally published in 1905, and revised in 1924. Rails manufactured to the 1905 standard were referred to as "O.B.S." (Original), and those manufactured to
7055-408: Was to increase rail height/foot-width ratio and strengthen the web. Disadvantages of the narrower foot were overcome through use of tie plates . AREA recommendations reduced the relative weight of rail head down to 36%, while alternative profiles reduced head weight to 33% in heavier weight rails. Attention was also focused on improved fillet radii to reduce stress concentration at the web junction with
7140-500: Was used in Germany in 1924. and has become common on 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 CWR segments. This
7225-430: Was widely used before more sophisticated profiles became cheap enough to make in bulk. It was notably used on the Great Western Railway 's 7 ft 1 ⁄ 4 in ( 2,140 mm ) gauge baulk road , designed by Isambard Kingdom Brunel . Barlow rail was invented by William Henry Barlow in 1849. It was designed to be laid straight onto the ballast , but the lack of sleepers (ties) meant that it
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