 |
It has been suggested that Vignoles rail be merged into this article or section. () |
|
|
It has been suggested that Flanged T rail be merged into this article or section. () |
|
|
It has been suggested that Tramway track#Grooved rail be merged into this article or section. () |
|
|
It has been suggested that Pound (rail) be merged into this article or section. () |
A Rail profile is a hot rolled steel profile of a specific shape or cross section (an asymmetrical 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. It took many decades to improve the quality of the materials, including the change from iron to steel. Minor flaws in the steel that pose no problems in reinforcing rods for buildings, can, however, lead to broken rails and dangerous derailments when used on railway tracks. By and large, the heavier the rails and the rest of the trackwork, the heavier and faster the trains these tracks can carry. The rails represent a substantial fraction of the cost of a railway line. Only a small number of rail sizes are made by the steelworks at the one time, so a railway must choose the nearest suitable size. Worn, heavy rail from a mainline is often cascaded down to branchline, siding or yard use.
Contents |
Rail sizes
Rails in Canada, the United Kingdom, and United States are still described using imperial units. However, in Australia they are now described in metric units and always have been on mainland Europe. Depending on the use of imperial or metric units, rail sizes are usually expressed in terms of pounds per yard or kilograms per metre. Coincidentally, the pounds-per-yard figure is almost exactly double the kilograms-per-metre figure, making rough conversions easy.
Europe
Rails are made in a large number of different sizes. Some common European rail sizes include:
|
|
In the countries of former USSR 65 kg/m rails are common. Thermally hardened 75 kg/m 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 rails[1].
North America
Some common North American rail sizes include:
|
|
Some common North American crane rail sizes include:
|
|
|
Australia
Some common Australian rail sizes include:
|
|
- 50 kg and 60 kg are the current standard, although some other sizes are still manufactured.
- Some American sizes are used on northwest Western Australian iron ore railways.
History
Early rails were used on horse drawn wagonways. In the early days the rails were flanged (i.e 'L' shaped) with the wagon wheels being flat. Over time it was realised that flanged wheels with flat rails worked better. Early rails were sometimes strap-iron rails, which consisted of thin strips of iron strapped onto wooden rails.[2] These rails were too fragile to carry heavy loads, but because the initial construction cost was less, this method was sometimes used to quickly build an inexpensive rail line. Strap 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." However, the long-term expense involved in frequent maintenance outweighed any savings. The earliest in general use were the so-called cast iron fishbelly rails from their shape. In time it became possible to roll longer lengths in wrought iron. 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.
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.
Early fishbelly metal rails made from cast iron were brittle and broke easily. They could only be made in short lengths which would soon become uneven. By 1840, wrought iron in longer lengths replaced cast iron as rolling techniques improved. The first steel rails were made in 1857 by Robert Forester Mushet, who laid them at Derby station in England. Steel was a much stronger material, which steadily replaced iron for use on railway rail and allowed much longer lengths of rails to be rolled. The use of welded rather than jointed track began in around the 1940s and had become widespread by the 1960s.
See also
References
- ^ message in the mailing list '1520mm' on Р75 rails.
- ^ Bianculli, Anthony J., Trains and Technology: The American Railroad in the Nineteenth Century, University of Delaware Press, 2002, Chapter 5, "From Strap Iron to High Iron". ISBN 0874138027
