Rail from 1896 showing manufacturer's name and specification impressed into the web of rail during rollingCross-sections of present-day flat-bottomed rail and (no longer installed) bullhead railEarly rails in USSection of theTranslohrguidance rail (during theClermont-Ferrand installation in 2006)
Therail profile is the cross-sectional shape of arail as installed on a railway or railroad, perpendicular to its length.
Early rails were made of wood, cast iron or wrought iron. All modern rails arehot rolledsteel with a cross section(profile) approximate to anI-beam, but asymmetric about a horizontal axis (however seegrooved 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 ofiron and steel, railway rails are subject to very high stresses and are made of very high quality steel. It took many decades to improve 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 dangerousderailments when used on railway tracks.
By and large, the heavier the rails and the rest of the track work, the heavier and faster thetrains these tracks can carry.
Rails represent a substantial fraction of 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 abranch line,siding oryard.
The earliest rails used on horse-drawnwagonways were wooden,.[1] In the 1760sstrap-iron rails were introduced with thin strips of cast iron fixed onto the top of the wooden rails. This increased the durability of the rails.[2] 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 the initial savings in construction costs.[3][2]
Cast-iron rails with vertical flanges were introduced byBenjamin Outram of B. Outram & Co. which later became theButterley Company in Ripley. The wagons that ran on theseplateway rails had a flat profile. Outram's partnerWilliam 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 theButterley Company.[4]
The earliest of these in general use were the so-called cast ironfishbelly rails from their shape. Rails made from cast iron werebrittle and broke easily. They could only be made in short lengths which would soon become uneven.John Birkinshaw's 1820 patent,[5] as rolling techniques improved, introducedwrought iron in longer lengths, replaced cast iron and contributed significantly to 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 asbullhead.
The first steel rails were made in 1857 byRobert Forester Mushet, who laid them atDerby station in England.[6] Steel is a much stronger material, which steadily replaced iron for use on railway rail and allowed much longer lengths of rails to be rolled.
TheAmerican Railway Engineering Association (AREA) and theAmerican 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 is preferentially oxidised by oxygen and is added to reduce the formation of weakening metal oxides in the rail rolling and casting procedures.[7] 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.[8]
The use of welded rather than jointed track began in around the 1940s and had become widespread by the 1960s.
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.[9]
Plate rail 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, asguide bars, with the Paris Métro (Rubber-tyred metro or FrenchMétro sur pneus) and more recently as theGuided bus. In theCambridgeshire Guided Busway the rail is a 350 mm (14 in) thick concrete beam with 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 was widely used before more sophisticated profiles became cheap enough to make in bulk. It was notably used on theGreat Western Railway's7 ft 1⁄4 in (2,140 mm)gaugebaulk road, designed byIsambard Kingdom Brunel.
Barlow rail was invented byWilliam Henry Barlow in 1849. It was designed to be laid straight onto theballast, but the lack ofsleepers (ties) meant that it was difficult to keep it in gauge.
Flanged T rail (also called T-section) is the name for flat bottomed rail used inNorth America.[dubious –discuss]Iron-strapped wooden rails were used on all American railways until 1831. Col.Robert L. Stevens, the President of theCamden and Amboy Railroad, conceived the idea that an all-iron rail would be better suited for building 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 could be rolled. Railways in the UK had been using rolled rail of other cross-sections which theironmasters had produced.[citation needed]
In May 1831, the first 500 rails, each 15 feet (4.6 m) long and weighing 36 pounds per yard (17.9 kg/m), reachedPhiladelphia and were placed in 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 thehooked spike for attaching the rail to thecrosstie (or sleeper). In 1860, thescrew spike was introduced in France where it was widely used.[10] Screw spikes are the most common form of spike in use worldwide in the 21st century.[citation needed]
When it became possible to preserve wooden sleepers withmercuric chloride (a process calledKyanising) andcreosote, they gave a much quieter ride than stone blocks and it was possible to fasten the rails directly usingclips orrail 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 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. TheLondon and Birmingham Railway, which had offered 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 bychairs fastened to the sleepers.[12]
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 the supporting chair would cause indentations in the lower surface of the rail, making it unsuitable as the running surface. Although theGreat Northern Railway did experience this problem, double-headed rails were successfully used and turned by theLondon and South Western Railway, theNorth Eastern Railway, theLondon, Brighton and South Coast Railway and theSouth Eastern Railway. Double-headed rails continued in widespread use in Britain until theFirst World War.[12]
Bullhead rail was developed from double-headed rail.[citation needed] 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 ironchairs 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 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).[13] One of the firstBritish Standards, BS 9, was for bullhead rail, which 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 the 1924 standard as "R.B.S." (Revised).[14]
Bullhead rail has been almost completely replaced by flat-bottom rail on the British rail system, although it survives on some branch lines andsidings. It can also be found onheritage railways, due both to the desire to maintain an historic appearance, and the use of old track components salvaged from main lines. TheLondon Underground continued to use bullhead rail after it had been phased out elsewhere in Britain but, in the last few years, there has been a concerted effort to replace it with flat-bottom rail.[15] However, the process of replacing track in tunnels is a slow one, due to the difficulty of using heavy plant and machinery.
Grooved rail, used when track is laid in places traversed by other vehicles or pedestrians
Where a rail is laid in aroad surface (pavement) or within grassed surfaces, there has to be accommodation for the flange. This is provided by aslot called the flangeway. The rail is then known asgrooved rail,groove rail, orgirder 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 byAlphonse Loubat, a French inventor who developed improvements intram and rail equipment, and helped develop tram lines in New York City and Paris.[16] The invention of grooved rail enabled tramways to be laid without causing a nuisance to other road users, except unsuspectingcyclists, 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 maintenanceroad-rail vehicle). Failure to clear the grooves can lead to a bumpy ride for the passengers, damage to either wheel or rail and possiblyderailing.
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 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 is required in the combined section.[17]
A modern block rail with a further reduction in mass is the LR55 rail[18] 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).[19]
Rails are made in a large number of different sizes. Some common European rail sizes include:
40 kg/m (81 lb/yd)
50 kg/m (101 lb/yd)
54 kg/m (109 lb/yd)
56 kg/m (113 lb/yd)
60 kg/m (121 lb/yd)
In the countries of theformer 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 likeBaikal–Amur Mainline, but have proven themselves deficient in operation and were mainly rejected in favor of 65 kg/m (131 lb/yd) rails.[citation needed]
Weight mark "155 PS" on a jointed segment of 155 lb/yd (76.9 kg/m) "Pennsylvania Special" rail, the heaviest grade of rail ever mass-producedCross-section drawing showing measurements in Imperial units for 100 lb/yd (49.6 kg/m) rail used in the United States,c. 1890sNew York Central System Dudley 127 lb/yd (63.0 kg/m) rail cross section
TheAmerican Society of Civil Engineers (or ASCE) specified rail profiles in 1893[21] 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 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, theAmerican 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 was to increase rail height/foot-width ratio and strengthen the web. Disadvantages of the narrower foot were overcome through use oftie 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 the head. AREA recommended the ARA 90 lb/yd (44.6 kg/m) profile.[22] Old ASCE rails of lighter weight remained in use, and satisfied the limited demand for light rail for a few decades. AREA merged into theAmerican Railway Engineering and Maintenance-of-Way Association in 1997.
By the mid-20th century, most rail production wasmedium heavy (112 to 119 lb/yd or 55.6 to 59.0 kg/m) andheavy (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, orlight rail. Track using 100 to 120 lb/yd (49.6 to 59.5 kg/m) rail is for lower speed freightbranch lines orrapid transit; for example, most of theNew York City Subway system track is constructed with 100 lb/yd (49.6 kg/m) rail.[citation needed] Main line track is usually built with 130 lb/yd (64.5 kg/m) rail or heavier. Some common North American rail sizes include:[23]
It has long been recognised thatconical wheels and rails that are sloped by the same amount follow curves better than cylindrical wheels and vertical rails. A few railways such asQueensland Railways for a long time had cylindrical wheels until much heavier traffic required a change.[29]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 the wheel is trued on a wheel lathe or replaced.[citation needed]
^"What Was a Railroad?".(Includes illustration of a length of strap rail.). Past Tracks. Archived fromthe original on 23 May 2011. Retrieved1 February 2011.
^American Society of Civil Engineers; American Society of Civil Engineers. Journal; International Engineering Congress (1893 : Chicago, Ill ); International Engineering Congress (1904 : St. Louis, Mo ) (1916).Transactions - American Society of Civil Engineers. Gerstein - University of Toronto. New York.{{cite book}}: CS1 maint: numeric names: authors list (link)
^Raymond, William G. (1937).The Elements of Railroad Engineering (5th ed.). John Wiley and Sons.
^Urquhart, Leonard Church, ed. (1959).Civil Engineering Handbook (4th ed.). McGraw-Hill Book Company.LCCN58011195.OL6249673M.
^"Hamersley freight line".Railway Technology. Global Data Marketing Solutions. 2024. Retrieved21 September 2024.
^Hagarty, D.D. (February 1999). "A short history of railway track in Australia—1 New South Wales—History and identification".Australian Railway Historical Society Bulletin.50 (736): 55.
