A narrow-gauge railway is a railway with a track gauge narrower than 1,435 mmstandard gauge. Most narrow-gauge railways are between 600 mm and 1,067 mm.
A standard-gauge railway is a railway with a track gauge of 1,435 mm. The standard gauge is also called Stephenson gauge, international gauge, UIC gauge, uniform gauge, normal gauge in Europe, and SGR in East Africa. It is the most widely used track gauge around the world, with about 55% of the lines in the world using it.
A broad-gauge railway is a railway with a track gauge broader than the 1,435 mm used by standard-gauge railways.
In rail transport, track gauge is the distance between the two rails of a railway track. All vehicles on a rail network must have wheelsets that are compatible with the track gauge. Since many different track gauges exist worldwide, gauge differences often present a barrier to wider operation on railway networks.
In railway engineering, "gauge" is the transverse distance between the inner surfaces of the heads of two rails, which for the vast majority of railway lines is the number of rails in place. However, it is sometimes necessary for track to carry railway vehicles with wheels matched to two different gauges. Such track is described as dual gauge – achieved either by addition of a third rail, if it will fit, or by two additional rails. Dual-gauge tracks are more expensive to configure with signals and sidings, and to maintain, than two separate single-gauge tracks. It is therefore usual to build dual-gauge or other multi-gauge tracks only when necessitated by lack of space or when tracks of two different gauges meet in marshalling yards or passenger stations. Dual-gauge tracks are by far the most common configuration, but triple-gauge tracks have been built in some situations.
With railways, a break of gauge occurs where a line of one track gauge meets a line of a different gauge. Trains and rolling stock generally cannot run through without some form of conversion between gauges, leading to passengers having to change trains and freight requiring transloading or transshipping; this can add delays, costs, and inconvenience to travel on such a route.
Railways with a railway track gauge of 5 ft first appeared in the United Kingdom and the United States. This gauge became commonly known as "Russian gauge", because the government of the Russian Empire chose it in 1843. Former areas and states of the Empire have inherited this standard. However in 1970, Soviet Railways re-defined the gauge as 1,520 mm.
Variable gauge systems allow railway vehicles to travel between two railways with different track gauges. Vehicles are equipped with variable gauge axles (VGA). The gauge is altered by driving the train through a gauge changer installed at the break of gauge which moves the wheels to the gauge desired.
Rail gauges in Australia display significant variations, which has presented an extremely difficult problem for rail transport on the Australian continent since the 19th century. As of 2022, there are 11,914 kilometres (7,403 mi) of narrow-gauge railways, 18,007 kilometres (11,189 mi) of standard gauge railways and 2,685 kilometres (1,668 mi) of broad gauge railways. In the 19th century, each of the colonies of Australia adopted their own gauges.
South Australian Railways (SAR) was the statutory corporation through which the Government of South Australia built and operated railways in South Australia from 1854 until March 1978, when its non-urban railways were incorporated into Australian National, and its Adelaide urban lines were transferred to the State Transport Authority.
The rail network in Queensland, Australia, was the first in the world to adopt 1,067 mm narrow gauge for a main line, and, in 2013, was claimed to the second largest narrow gauge network in the world, consists of:
Rail transport in Australia involves a number of narrow-gauge railways. In some states they formed the core statewide network, but in the others they were either a few government branch lines, or privately owned and operated branch lines, often for mining, logging or industrial use.
Bogie exchange is a system for operating railway wagons on two or more gauges to overcome difference in the track gauge. To perform a bogie exchange, a car is converted from one gauge to another by removing the bogies or trucks, and installing a new bogie with differently spaced wheels. It is generally limited to wagons and carriages, though the bogies on diesel locomotives can be exchanged if enough time is available.
The N Class are a class of diesel locomotives built by Clyde Engineering in Somerton for V/Line between 1985 and 1987.
Railways with a track gauge of 5 ft 3 in fall within the category of broad gauge railways. As of 2022, they were extant in Australia, Brazil and on the island of Ireland.
5 ft 6 in (1,680 mm) is a broad track gauge, used in India, Pakistan, western Bangladesh, Sri Lanka, Argentina, Chile, and on BART in the San Francisco Bay Area.
Iberian gauge is a track gauge of 1,668 mm, most extensively used by the railways of Spain and Portugal. A broad gauge, it is the second-widest gauge in regular use anywhere in the world, with only Indian gauge railways, 5 ft 6 in, being wider.
The DB Class V 51 and DB Class V 52 are classes of almost identical narrow gauge 4 axle diesel hydraulic locomotives built in 1964 for the Deutsche Bundesbahn, being built for 750 mm and 1,000 mm gauge lines respectively.
The 700 class is a class of six diesel-electric locomotives based on the Alco DL500G model, built by AE Goodwin, Auburn, New South Wales for the South Australian Railways. They are virtually identical to the New South Wales 442 class locomotive.
Port Pirie railway station (Mary Elie Street) was the fifth of six railway stations for passengers that operated at various times from 1876 to serve the small maritime town (later city) of Port Pirie, 216 kilometres (134 miles) by rail north of Adelaide, South Australia. As with several of Port Pirie's other stations before it, the station was built to accommodate a change of track gauge on railway lines leading into the town.
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