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The standard gauge (also Stephenson gauge after George Stephenson, International gauge, or normal gauge) is a widely used railway track gauge. Approximately 55% of the lines in the world are this gauge. All high-speed rail lines, except those in Russia, Uzbekistan, and Finland, are standard gauge. The distance between the inside edges of the rails is defined to be 1435 mm except in the United States, where it is still defined in Imperial and US customary units as 4 feet 8 1⁄2 inches (1,435.1 mm). It is also called the UIC gauge or UIC track gauge, the European gauge in the EU and Russia, or uniform gauge in Queensland, Australia.
Contents
History
As railways developed and expanded, one of the key issues was the track gauge (the distance, or width, between the inner sides of the rails) to be used. The result was the adoption throughout a large part of the world of a "standard gauge" of 1435 mm (4 ft 8 1⁄2 in), allowing inter-connectivity and inter-operability.
In North East England, some early lines in colliery (coal mining) areas were 4 ft 8 in (1,422 mm), whilst in Scotland some early lines were 4 ft 6 in (1,372 mm). All these lines had been widened to standard gauge by 1846. Parts of the United States, mainly in the Northeast, adopted the same gauge, because some early trains were purchased from Britain. However, until well into the second half of the 19th century, Britain and the USA used several different track gauges. The American gauges converged as the advantages of equipment interchange became increasingly apparent; notably, the South's 5 ft (1,524 mm) broad gauge was converted to be compatible with standard gauge over the course of two days beginning on 31 May 1886. See Track gauge in the United States.
With the advent of metrication, standard gauge was redefined as 1,435 mm, a reduction of 0.1 mm but well within existing tolerance limits, with the exception of the United States and Canada, where standard gauge continues to be defined in terms of feet and inches.
Origins
A popular legend that has been around since at least 1937 traces the origin of the 1435 mm (4 ft 8 1⁄2 in) gauge even further back than the coalfields of northern England, pointing to the evidence of rutted roads marked by chariot wheels dating from the Roman Empire. Snopes categorized this legend as "false", but commented that "... it is perhaps more fairly labelled as 'True, but for trivial and unremarkable reasons.'" The historical tendency to place the wheels of horse-drawn vehicles approximately 5 feet (1,500 mm) apart probably derives from the width needed to fit a carthorse in between the shafts. In addition, while road-traveling vehicles are typically measured from the outermost portions of the wheel rims (and there is some evidence that the first railroads were measured in this way as well), it became apparent that for vehicles travelling on rails it was better to have the wheel flanges located inside the rails, and thus the distance measured on the inside of the wheels (and, by extension, the inside faces of the rail heads), was the important one.
There was no standard gauge for horse railways, but there were rough groupings: in the north of England none was less than 4 ft (1,219 mm). Wylam colliery's system, built before 1763, was 5 ft (1,524 mm), as was John Blenkinsop's Middleton Railway; the old 4 ft (1,219 mm) plateway was relaid to 5 ft (1,524 mm) so that Blenkinsop's engine could be used. Others were 4 ft 4 in (1,321 mm) (in Beamish) or 4 ft 7 1⁄2 in (1,410 mm) (Bigges Main and Kenton and Coxlodge).
The English railway pioneer George Stephenson spent much of his early engineering career working for the coal mines of County Durham. He favoured 4 ft 8 in (1,422 mm) for wagonways in Northumberland and Durham, and used it on his Killingworth line. The Hetton and Springwell wagonways also used this gauge.
Stephenson's Stockton and Darlington railway (S&DR) was built primarily to transport coal from mines near Shildon to the port at Stockton-on-Tees. The initial gauge of 4 ft 8 in (1,422 mm) was set to accommodate the existing gauge of hundreds of horse-drawn chaldron wagons that were already in use on the wagonways in the mines. The railway used this gauge for 15 years before a change was made to 4 ft 8 1⁄2 in gauge. The historic Mount Washington Cog Railway, the world's first mountain-climbing rack railway, is still in operation in the 21st century, and has used the earlier 4 ft 8 in gauge since its inauguration in 1868.
The beginnings of the 4 ft 8 1⁄2 in gauge
George Stephenson used the 4 ft 8 1⁄2 in gauge (including a belated extra 1⁄2 in (13 mm) of free movement to reduce binding on curves) for the Liverpool and Manchester Railway, authorised in 1826 and opened 30 September 1830. The success of this project led to Stephenson and his son Robert being employed to engineer several other larger railway projects.
Non-standard gauge
Almost standard gauge
Standard gauge
authorised 1829, opened 1834, isolated from LMR, engineered by Robert Stephenson.
During the "gauge war" with the Great Western Railway, standard gauge was called "narrow gauge". The modern use of narrow gauge for gauges less than standard did not arise for 20 years, until the first such locomotive-hauled passenger railway, the Ffestiniog Railway.
Dual gauge
The Royal Commission
In 1845, in the United Kingdom of Great Britain and Ireland, a Royal Commission on Railway Gauges reported in favour of a standard gauge. In Great Britain, Stephenson's gauge was chosen on the grounds that lines of this gauge were eight times longer than those of the rival 7 ft (2,134 mm) (later 7 ft 1⁄4 in (2,140 mm)) gauge adopted principally by the Great Western Railway. The subsequent Gauge Act ruled that new passenger-carrying railways in Great Britain should be built to a standard gauge of 1,435 mm (4 ft 8 1⁄2 in), and those in Ireland to a new standard gauge of 5 ft 3 in (1,600 mm). It allowed the broad-gauge companies in Great Britain to continue with their tracks and expanding their networks within the "Limits of Deviation" and the exceptions defined in the Act. After an intervening period of mixed-gauge operation (tracks were laid with three rails), the Great Western Railway finally converted its entire network to standard gauge in 1892.
The Royal Commission made no comment about small to-be-called "narrow"-gauge lines, such as the Ffestiniog Railway, which allowed a future multiplicity of small gauges in the UK; it also made no comments about future gauges in British colonies.
Regrets
Robert Stephenson was reported to have said that if he had had a second chance to choose a standard gauge, he would have chosen one wider than 1,435 mm (4 ft 8 1⁄2 in). "I would take a few inches more, but a very few".
Modern almost-standard gauge railways
Road vehicles
Several states in the United States had laws requiring road vehicles to have a consistent gauge to allow them to follow ruts in the road. These gauges were similar to railway standard gauge.