A standard-gauge railway is a railway with a track gauge of 1,435 mm (4 ft 8 1⁄2 in). The standard gauge is also called Stephenson gauge after George Stephenson, International gauge, UIC gauge, uniform gauge, normal gauge and European gauge in the European Union and Russia. It is the most widely used railway track gauge across the world, with approximately 55% of the lines in the world using it. All high-speed rail lines use standard gauge except those in Russia, Finland, Portugal and Uzbekistan. The distance between the inside edges of the rails is defined to be 1435 mm except in the United States and on some heritage British lines, where it is still defined in U.S. customary units as exactly "four feet eight and one half inches" (0.1 mm larger than the metric standard).
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. Different railways used different gauges, and where rails of different gauge met – a "gauge break" – loads had to be unloaded from one set of rail cars and re-loaded onto another, a time-consuming and expensive process. 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 interconnectivity and interoperability.
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. It is curious that the Roman pace or passus was 4.855 ft or 1435 mm; a thousand such was one Roman mile. Snopes categorised 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 ft (1,524 mm) apart probably derives from the width needed to fit a carthorse in between the shafts. In addition, while road-travelling vehicles are typically measured from the outermost portions of the wheel rims (and there is some evidence that the first railways 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 never a 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) (in Bigges Main (in Wallsend), 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 the 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.
George Stephenson used the 4 ft 8 1⁄2 in gauge (including a belated extra 1⁄2 in (12.7 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. Thus the 4 ft 8 1⁄2 gauge became widespread and dominant in Britain. Robert 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 4 ft 8 1⁄2 in (1,435 mm). "I would take a few inches more, but a very few".
During the "gauge war" with the Great Western Railway, standard gauge was called narrow gauge, in contrast to the Great Western's 7 ft 1⁄4 in (2,140 mm) broad gauge. The modern use of the term "narrow gauge" for gauges less than standard did not arise for many years, until the first such locomotive-hauled passenger railway, the Ffestiniog Railway was built.
In 1845, in the United Kingdom of Great Britain and Ireland, a Royal Commission on Railway Gauges reported in favour of a standard gauge. The subsequent Gauge Act ruled that new passenger-carrying railways in Great Britain should be built to a standard gauge of 4 ft 8 1⁄2 in (1,435 mm), and those in Ireland to a new standard gauge of 5 ft 3 in (1,600 mm). In Great Britain, Stephenson's gauge was chosen on the grounds that existing 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. It allowed the broad-gauge companies in Great Britain to continue with their tracks and expand 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 completed the conversion of its network to standard gauge in 1892. In North East England, some early lines in colliery (coal mining) areas were 4 ft 8 in (1,422 mm), while in Scotland some early lines were 4 ft 6 in (1,372 mm). All these lines had been widened to standard gauge by 1846. The British gauges converged starting from 1846 as the advantages of equipment interchange became increasingly apparent. By the 1890s, the entire network was converted to standard gauge.
The Royal Commission made no comment about small lines narrower than standard gauge (to be called "narrow gauge"), such as the Ffestiniog Railway. Thus it permitted a future multiplicity of narrow gauges in the UK. It also made no comments about future gauges in British colonies, which allowed various gauges to be adopted across the colonies.
Parts of the United States, mainly in the Northeast, adopted the same gauge, because some early trains were purchased from Britain. The American gauges converged, as the advantages of equipment interchange became increasingly apparent. Notably, all the 5 ft (1,524 mm) broad gauge track in the South was converted to "almost standard" gauge 4 ft 9 in (1,448 mm) over the course of two days beginning on 31 May 1886. See Track gauge in the United States.
In continental Europe, France and Belgium adopted a 1,500 mm (4 ft 11 1⁄16 in) gauge (measured between the midpoints of each rail's profile) for their early railways. The gauge between the interior edges of the rails (the measurement adopted from 1844) differed slightly between countries, and even between networks within a country (for example, 1,440 mm or 4 ft 8 11⁄16 in to 1,445 mm or 4 ft 8 7⁄8 in in France). The first tracks in Austria and in the Netherlands had other gauges (1,000 mm or 3 ft 3 3⁄8 in in Austria for the Donau Moldau linen and 1,945 mm or 6 ft 4 9⁄16 in in the Netherlands for the Hollandsche IJzeren Spoorweg-Maatschappij), but for interoperability reasons (the first rail service between Paris and Berlin began in 1849, first Chaix timetable) Germany adopted standard gauges, as did most other European countries.
The modern method of measuring rail gauge was agreed in the first Berne rail convention of 1886, according to the "Revue générale des chemins de fer, July 1928".
Early railways by gauge
- Monkland and Kirkintilloch Railway, authorised 1824 and opened 1825, used 4 ft 6 in (1,372 mm).
- Dundee and Newtyle Railway, authorised 1829 and opened 1831, used 4 ft 6 1⁄2 in (1,384 mm).
- the Eastern Counties Railway, authorised on 4 July 1836, used 5 ft (1,524 mm)
- the London and Blackwall Railway, authorised on 28 July 1836, used 5 ft 1⁄2 in (1,537 mm).
- the Dundee and Arbroath Railway, incorporated on 19 May 1836 and opened October 1838, used 5 ft 6 in (1,676 mm) until standardised in 1847.
- the Arbroath and Forfar Railway, incorporated on 19 May 1836 and opened November 1838, used 5 ft 6 in (1,676 mm).
- the Northern and Eastern Railway, authorised on 4 July 1836, used 5 ft (1,524 mm) gauge.
- Aberdeen Railway, opened 1848, used 5 ft 6 in (1,676 mm) until standardised.
- the Killingworth colliery railway, used 4 ft 8 in (1,422 mm).
- the Hetton colliery railway, opened 1822, used 4 ft 8 in (1,422 mm).
- the Stockton and Darlington Railway, authorised 1821, opened 1825, used 4 ft 8 in (1,422 mm).
- the Manchester and Leeds Railway, authorised on 4 July 1836, used 4 ft 9 in (1,448 mm). The 4 ft 9 in (1,448 mm) railways were intended to take 4 ft 8 1⁄2 in (1,435 mm) gauge vehicles and allow a (second) running tolerance.
- the Chester and Birkenhead Railway, authorised on 12 July 1837, used 4 ft 9 in (1,448 mm).
- the London and Brighton Railway, authorised on 15 July 1837, used 4 ft 9 in (1,448 mm).
- the Grand Junction Railway, authorised 1833, opened 1837, connected to LMR.
- the Manchester and Birmingham Railway, authorised on 30 June 1837, used 4 ft 9 in (1,448 mm).
- the trams in Dresden, authorised in 1872 as horsecars, used 1,440 mm (4 ft 8 11⁄16 in) gauge vehicles. Converted to 600 V DC electric trams in 1893, they now use 1,450 mm (4 ft 9 3⁄32 in); both gauges are within the tolerance for standard gauge.
- the trams in Nuremberg nominally used 1,432 mm (4 ft 8 3⁄8 in) during much of their existence, but have since been converted to standard gauge in name as well as fact
- the Liverpool and Manchester Railway, authorised 1824, opened 1830.
- the Saint-Étienne–Lyon railway, authorised 1826, opened 1833 ( all the early French railways including Saint-Etienne Andrezieux, authorised 1823, opened 1827 had a French Gauge of 1,500 mm (4 ft 11 1⁄16 in) from rail axis to rail axis, compatible with early standard gauge tolerances)
- the Dublin and Kingstown Railway, authorised 1831, opened for passenger traffic 1834.
- the Newcastle & Carlisle Railway, authorised 1829, opened 1834, isolated from LMR.
- the Grand Junction Railway, authorised 1833, opened 1837, connected to LMR.
- the London and Birmingham Railway, authorised 1833, opened 1838, connected to LMR.
- the Manchester and Birmingham Railway, authorised 1837, opened 1840, connected to LMR.
- the Birmingham and Gloucester Railway, authorised 1836, opened 1840, connected to LMR.
- the London and Southampton Railway, authorised 1834, opened 1840.
- the London and Brighton Railway, authorised 1837, opened 1841.
- the South Eastern Railway, authorised 1836, opened 1844.
- Cheltenham and Great Western Union Railway, authorised 1836, opened 1840, dual gauge 1843 4 ft 8 1⁄2 in (1,435 mm) standard gauge and 7 ft 1⁄4 in (2,140 mm).
Modern almost standard gauge railways
- The Toronto Transit Commission uses 1,495 mm (4 ft 10 7⁄8 in) gauge on its streetcar and subway lines, which was actually closer to 1,520 mm (4 ft 11 27⁄32 in) gauge. However, the Eglinton Crosstown Line will use 1,435 mm (4 ft 8 1⁄2 in) gauge.
- Trams in Dresden, Germany use 1,450 mm (4 ft 9 3⁄32 in)
- Trams in Leipzig, Germany use 1,458 mm (4 ft 9 13⁄32 in)
- 1,445 mm (4 ft 8 7⁄8 in) gauge is in use on several urban rail transit systems in Europe: Trams in Italy Madrid Metro (only metro system. Light rail system uses 1,435 mm (4 ft 8 1⁄2 in) gauge)
- The MTR in Hong Kong uses 1,432 mm (4 ft 8 3⁄8 in) gauge on lines owned by the MTR Corporation. However, lines formerly operated (but which continue to be owned) by the Kowloon-Canton Railway Corporation, including the Light Rail network, use 1,435 mm (4 ft 8 1⁄2 in) gauge.
- The Bucharest Metro uses 1,432 mm (4 ft 8 3⁄8 in) gauge.
- The Washington Metro uses 4 ft 8 1⁄4 (1,429 mm), 1⁄4 in (6 mm) narrower than standard gauge.
- The Mount Washington Cog Railway, the world's oldest mountain-climbing rack-and-pinion railway, uses a 4 ft 8 in (1,422 mm) gauge.