The standard gauge (also named the Stephenson gauge after George Stephenson, or Normal gauge) is a widely-used rail gauge. Approximately 60% of the world's existing railway lines are built to this gauge (see the list of countries that use the standard gauge). The distance between the inside edges of the rails of standard gauge track is 1,435 mm (4 ft 8½ in).

History

The dominant rail gauge in each country shown:

ft' in"	mm
5' 6"	1676
5' 5.85"	1668
5' 3"	1600
5'	1524
4' 11.85"	1520
4' 8.5"	1435
4' 6"	1372
3' 6"	1067
3' 5.35"	1050
3' 3.35"	1000
3' 4.1"	950
3'	914
2' 6"	762
2' 5.55"	750
2'	610
1' 11.6"	600

As railways developed and expanded one of the key issues to be decided was that of the rail gauge (the distance, or width, between the inner sides of the rails) that should be used. The eventual result was the adoption throughout a large part of the world of a "standard gauge" of 1,435 mm (4 ft 8½ in), allowing inter-connectivity and the inter-operability of trains.

In England some early lines in colliery (coal mining) areas in the north east of the country were built to a gauge of 4 ft 8 in (1,422 mm); and in Scotland some early lines were 4 ft 6 in (1,372 mm) (Scotch gauge). By 1846, in both countries, these lines were widened to standard gauge. Parts of the United States rail system, 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 had several different track gauges. The American gauges slowly converged as the advantages of equipment interchange became more and more apparent; the destruction of much of the South's 5 ft (1,524 mm) broad gauge system in the American Civil War hastened this trend.

Origins

A popular legend traces the origin of the 1,435 mm (4 ft 8½ 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. This legend has been debunked.¹ The historical tendency to place the wheels of horse-drawn vehicles approximately 1,524 mm (5 ft) apart probably derives from the width needed to fit a carthorse in between the shafts^{citation needed}. 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 were less than 4ft.² Wylam colliery's system, built before 1763, was 5 ft 0 in; as was John Blenkinsop's Middleton Railway, the old 4ft plateway was relaid to 5ft so that Blenkinsop's engine could be used.² Others were 4 ft 4 in Beamish or 4ft 7.5in (Bigges Main and Kenton and Coxlodge).²

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 for waggonways in Northumberland and Durham and used it on his Killingworth line.² The Hetton and Springwell waggonways also used the gauge.

Stephenson's Stockton and Darlington railway (S&DR) was built primarily to transport coal from several mines near Shildon to the port at Stockton-on-Tees. The S&DR's initial track 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. It was built and used at this gauge for fifteen years before being changed to 4 ft 8½ in (1,435 mm) gauge.²³

The beginnings of the 4ft 8½in gauge

George Stephenson used the 4 ft 8½ in (1,435 mm) gauge (with an extra half-inch of free movement to reduce binding on curves³) for the Liverpool and Manchester Railway, authorised in 1826 and opened 30 September 1830. The success of this project led to George Stephenson and his son Robert being employed to engineer several other larger railway projects. However, the Chester and Birkenhead Railway, authorised on 12 July 1837, was 4 ft 9 in; ⁴ the Eastern Counties Railway, authorised on 4 July 1836, was 5 ft 0 in; ⁵ London and Blackwall Railway, authorised on 28 July 1836, was 5 ft 0 in; ⁶ the London and Brighton Railway, authorised on 15 July 1837, was 4 ft 9 in; ⁷ the Manchester and Birmingham Railway, authorised on 30 June 1837, was 4 ft 9 in; ⁸ the Manchester and Leeds Railway, authorised on 4 July 1836, was 4 ft 9 in ⁹ the Northern and Eastern Railway, authorised on 4 July 1836, was 5 ft 0 in.¹⁰ The 4 ft 9 in railways were intended to take 4 ft 8½ in (1,435 mm) gauge vehicles and allow a running tolerance.

The influence of the Stephensons appears to be the main reason that the 4 ft 8½ in (1,435 mm) gauge became the standard, and its usage became more widespread than any other gauge.^{citation needed}.

The Royal Commission

In the United Kingdom of Great Britain and Ireland, a Royal Commission in 1845 reported in favour of a standard gauge. In Great Britain, Stephenson's gauge was chosen as the standard gauge on the grounds that lines built to this gauge were eight times longer than that of the rival 7 ft 0¼ 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 4 ft 8½ in (1,435 mm); and those in Ireland to a standard gauge 5 ft 3 in (1,600 mm). It allowed the broad gauge companies in Great Britain to continue repairing 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 running-rails), the Great Western Railway finally converted its entire network to standard gauge in 1892.

Pioneer lines

The longest serving engineer of the New South Wales Railways was always being pressured to cut costs on new construction, by using horses or by using a narrower gauge. He resisted as much as possible, but did eventually introduce so-called pioneer lines for more remote and lightly trafficked areas.

See also

References

Footnotes

Sources

• Baxter, Bertran (1966). Stone blocks and iron rails (Tramroads) (Industrial Archaeology of the British Isles). Newton Abbot: David & Charles.
• Whishaw, Francis (1842). The Railways of Great Britain and Ireland: practically described and illustrated. London: John Weale (Republished 1969. David & Charles Reprints. Newton Abbot: David & Charles. ISBN 0-7153-4786-1.)

Further reading

• Pomeranz, Kenneth and Steven Topik (1999). The World That Trade Created: Society, Culture, and World Economy, 1400 to the Present, M.E. Sharpe, Inc., Armonk, NY. ISBN 0-7656-0250-4. 

External links

• Urban Legends Reference Pages: Railroad Gauges and Roman Chariots (Snopes)
• Jane's World Railways (hard copy)
• A learned text of standardisation of gauge