As
railways developed and expanded, one of the key issues was the
track gauge (the distance, or width, between the inner sides of the rail heads) to be used, as the wheels of the
rolling stock (locomotives, cars, etc.) must match this distance. Different railways used different gauges, and where track of different gauges met – a "
gauge break" – loads had to be unloaded from one set of rail cars and reloaded 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 , allowing interconnectivity and interoperability.
Origins A popular legend that has circulated since at least 1937 traces the origin of the 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 categorised this legend as "false", but commented that it "is perhaps more fairly labeled as 'Partly true, but for trivial and unremarkable reasons. The historical tendency to place the wheels of horse-drawn vehicles around 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, it became apparent that for vehicles travelling on rails, having main
wheel flanges that fit
inside the rails is better, thus the minimum distance between the wheels (and, by extension, the inside faces of the
rail heads) was the important one. A standard gauge for horse railways never existed, but rough groupings were used; in the north of England none was less than .
Wylam colliery's system, built before 1763, was , as was
John Blenkinsop's
Middleton Railway; the old plateway was relaid to so that Blenkinsop's engine could be used. Others were (in
Beamish) or (in
Bigges Main (in
Wallsend),
Kenton, and
Coxlodge).
Stone block sleepers Very early tramways used pairs of stone blocks which meant that the feet of horses didn't trip over obstacles in the middle of the track. However timber sleepers, which could cause the feet of horses to trip, held the gauge better.
Pioneer gauges English railway pioneer
George Stephenson spent much of his early engineering career working for the coal mines of
County Durham. He favoured
() 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. Opening in 1825, the initial gauge of 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, debuting around 1850, to the 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 gauge since its inauguration in 1868. George Stephenson introduced the gauge (including a belated extra of free movement to reduce binding on curves) for the
Liverpool and Manchester Railway, authorised in 1826 and opened 30 September 1830. The extra half inch was not regarded at first as very significant, and some early trains ran on both gauges daily without compromising safety. The success of this project led to Stephenson and his son
Robert being employed to engineer several other larger railway projects. Thus the gauge became widespread and dominant in Britain. Robert was reported to have said that if he had had a second chance to choose a gauge, he would have chosen one wider than . "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
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.
Gauge in Ireland Ireland built its first railway with standard 1435mm gauge, but switched to
1600mm gauge after a decree from the
Board of Trade.
Early Example An early example of 1435mm gauge was at
Willington Colliery, a 3-mile line running to the River Tyne.
Adoption 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 , and those in Ireland to a new standard gauge of . 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 (later ) 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 , while in
Scotland some early lines were . 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
broad gauge track in the
South was converted to "almost standard" gauge 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 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, to in France). The first tracks in Austria and in the Netherlands had other gauges ( in Austria for the Donau Moldau line and 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. ==Early railways by gauge==