Editing Track gauge (section)

==Choice of gauge==

===Early track gauges===
{{See also|Permanent way (history)|Wagonway|Plateway}}

The earliest form of railway was a wooden wagonway, along which single wagons were manhandled, almost always in or from a mine or quarry. Initially the wagons were guided by human muscle power; subsequently by various mechanical methods. Timber rails wore rapidly: later, flat cast-iron plates were provided to limit the wear. In some localities, the plates were made L-shaped, with the vertical part of the L guiding the wheels; this is generally referred to as a "plateway". Flanged wheels eventually became universal, and the  spacing between the rails had to be compatible with that of the wagon wheels.<ref name="lewis">M. J. T. Lewis (1970), ''Early Wooden Railways'', Routledge Keegan Paul, London</ref>

As the guidance of the wagons was improved, short strings of wagons could be connected and pulled by teams of horses, and the track could be extended from the immediate vicinity of the mine or quarry, typically to a navigable waterway. The wagons were built to a consistent pattern and the track would be made to suit the needs of the horses and wagons: the gauge was more critical. The [[Merthyr Tramroad|Penydarren Tramroad]] of 1802 in South Wales, a plateway, spaced these at {{Track gauge|4ft4in}} over the outside of the upstands.<ref name =" cragg">R. Cragg (1997), ''Civil Engineering Heritage – Wales and West Central'', Thomas Telford Publishing, London, 2nd edition, England, {{ISBN|0 7277 2576 9}}</ref>

[[File:Chpr rail.jpg|thumb|right|Fish-belly cast-iron rails from the Cromford and High Peak Railway]]
The Penydarren Tramroad probably carried the first journey by a locomotive, in 1804, and it was successful for the locomotive, but unsuccessful for the track: the plates were not strong enough to carry its weight. A considerable progressive step was made when cast iron edge rails were first employed; these had the major axis of the rail section configured vertically, giving a much stronger section to resist bending forces, and this was further improved when fish-belly rails were introduced.<ref name="earlyrailways">Andy Guy and Jim Rees, ''Early Railways 1569–1830'', Shire Publications in association with the National Railway Museum, Oxford, 2011, {{ISBN|978 0 74780 811 4}}</ref>

Edge rails required a close match between rail spacing and the configuration of the wheelsets, and the importance of the gauge was reinforced. Railways were still seen as local concerns: there was no appreciation of a future connection to other lines, and the choice of track gauge was still a pragmatic decision based on local requirements and prejudices, and probably determined by existing local designs of (road) vehicles.

Thus, the [[Monkland and Kirkintilloch Railway]] (1826) in the West of Scotland used {{Track gauge|4ft6in}};<ref name = martin>Don Martin, ''The Monkland and Kirkintilloch and Associated Railways'', Strathkelvin Public Libraries, Kirkintilloch, 1995, {{ISBN|0 904966 41 0}}</ref> the [[Dundee and Newtyle Railway]] (1831) in the north-east of Scotland adopted {{Track gauge|4 ft 6 1/2 in}};<ref name = ferguson>N. Ferguson (1995), ''The Dundee and Newtyle Railway including the Alyth and Blairgowrie Branches'', The Oakwood Press, {{ISBN|0-85361-476-8}}.</ref> the [[Redruth and Chasewater Railway]] (1825) in Cornwall chose {{Track gauge|4ft}}.<ref>D. B. Barton (1966), ''The Redruth and Chasewater Railway, 1824–1915'', D. Bradford Barton Ltd, Truro, 2nd edition</ref>

The [[Arbroath and Forfar Railway]] opened in 1838 with a gauge of {{Track gauge|5ft6in}},<ref name = whishaw>[[Francis Whishaw]], ''The Railways of Great Britain and Ireland Practically Described and Illustrated'', 1842, reprint 1969, David & Charles (Publishers) Limited, Newton Abbot, {{ISBN|0-7153-4786-1}}</ref> and the [[Ulster Railway]] of 1839 used {{Track gauge|6ft2in}}.<ref name = whishaw/>

==="Standard" gauge appears===
[[File:Killingworth-locomotive.jpg|thumb|An early Stephenson locomotive]]Locomotives were being developed in the first decades of the 19th century; they took various forms, but [[George Stephenson]] developed a successful locomotive on the [[Killingworth Wagonway]], where he worked. His designs were successful, and when the [[Stockton and Darlington Railway]] was opened in 1825, it used his locomotives, with the same gauge as the [[Killingworth line]], {{Track gauge|4ft8in}}.<ref name = tomlinson>W W Tomlinson, ''The North Eastern Railway, its Rise and Development'', Andrew Reid & Co, Newcastle upon Tyne, 1915</ref><ref name = wood>Nicholas Wood, ''A Practical Treatise on Rail-Roads'', Longman, Orme, Brown, Green and Longmans, London, Third edition, 1838</ref>

The Stockton and Darlington line was very successful, and when the [[Liverpool and Manchester Railway]], the first intercity line, was opened in 1830, it used the same gauge. It too was very successful, and the gauge, widened to {{Track gauge|4ft8.5in|disp=or}}<ref name = tomlinson/> and named "[[standard gauge]]", was well on its way to becoming the established norm.

===Gauge differences===
The Liverpool and Manchester was quickly followed by other trunk railways, with the [[Grand Junction Railway]] and the [[London and Birmingham Railway]] forming a huge preponderance of [[standard gauge]]. When Bristol promoters planned a line from London, they employed the innovative engineer [[Isambard Kingdom Brunel]]. He decided on a wider gauge, to give greater stability, and the [[Great Western Railway]] adopted a gauge of {{Track gauge|7ft}}, later eased to {{Track gauge|7ft0.25in|lk=on}}. This became known as ''[[broad gauge]]''. The [[Great Western Railway]] (GWR) was successful and was greatly expanded, directly and through friendly associated companies, widening the scope of broad gauge.

At the same time, other parts of Britain built railways to standard gauge, and British technology was exported to European countries and parts of North America, also using standard gauge. Britain polarised into two areas: those that used [[Brunel gauge|broad gauge]] and those that used standard gauge. In this context, standard gauge was referred to as "narrow gauge" to indicate the contrast. Some smaller concerns selected other non-standard gauges: the [[Eastern Counties Railway]] adopted {{Track gauge|5ft|lk=on}}. Most of them converted to standard gauge at an early date, but the GWR's broad gauge continued to grow.

The larger railway companies wished to expand geographically, and large areas were considered to be under their control. When a new independent line was proposed to open up an unconnected area, the gauge was crucial in determining the allegiance that the line would adopt: if it was broad gauge, it must be friendly to the Great Western railway; if narrow (standard) gauge, it must favour the other companies. The battle to persuade or coerce that choice became very intense, and became referred to as the [[British Gauge War|"gauge wars"]].

As passenger and freight transport between the two areas became increasingly important, the difficulty of moving from one gauge to the other—the ''[[break-of-gauge]]''—became more prominent and more objectionable. In 1845 a [[Royal Commission on Railway Gauges]] was created to look into the growing problem, and this led to the [[Regulating the Gauge of Railways Act 1846]],<ref>{{cite web
| url = http://www.railwaysarchive.co.uk/documents/HMG_Act_Reg1846.pdf
| title =An Act for regulating the Gauge of Railways
|date = 18 October 1846
|access-date =26 April 2010}}</ref> which forbade the construction of broad gauge lines unconnected with the broad gauge network. The broad gauge network was eventually converted—a progressive process completed in 1892, called [[Track gauge conversion|gauge conversion]]. The same Act mandated the gauge of {{Track gauge|5ft3in|lk=on}} for use in Ireland.

===Gauge selection in other countries===
[[File:World RR Gauge Map.agr.png|thumb|300px|Map of the world's railways showing the different gauges in use. {{ubl |{{legend|#a100ff|[[3 ft gauge railways|3 ft gauge]] (914 mm)}}
|{{legend|#6000ff|[[Meter gauge]] (1,000 mm)}}
|{{legend|#0500e0|[[3 ft 6 in gauge railways|Cape gauge]] (1,067 mm)}}
|{{legend|#000000|[[Standard gauge]] (1,435 mm)}}
|{{legend|#c00100|[[Russian gauge]] (1,520 mm)}}
|{{legend inline|#ff0100|[[Five foot gauge]] (1,524 mm)}}
|{{legend|#ffa000|[[Irish gauge]] (1,600 mm)}}
|{{legend|#ffc000|[[Iberian gauge]] (1,668 mm)}}
|{{legend|#ffe000|[[Indian gauge]] (1,676 mm)}}
}}
]]
[[File:Different gauges in China Railway Museum.jpg|thumb|right|upright|[[Triple gauge]], from left: {{Track gauge|1435mm}}, {{Track gauge|1000mm}}, and {{Track gauge|600mm}}, on display at the [[China Railway Museum]] in [[Beijing]]]] As railways were built in other countries, the gauge selection was pragmatic: the track would have to fit the rolling stock. If locomotives were imported from elsewhere, especially in the early days, the track would be built to fit them. In some cases standard gauge was adopted, but many countries or companies chose a different gauge as their national gauge, either by governmental policy, or as a matter of individual choice.<ref>''[https://digital.lib.washington.edu/researchworks/bitstream/handle/1773/21998/Starns_washington_0250O_10676.pdf The Russian Railways and Imperial Intersections in the Russian Empire]'', Karl E. M. Starns, Thesis, University of Washington 2012, p. 33</ref>