Gauge conversion is the changing of one railway

track gauge In rail transport, track gauge (in American English, alternatively track gage) 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 ...

(the distance between the running rails) to another.

Sleepers

If tracks are converted to a narrower gauge, the existing sleepers (ties) may be used. However, replacement is required if the conversion is to a wider gauge. Some sleepers may be long enough to accommodate the fittings of both existing and alternative gauges. Wooden sleepers are suitable for conversion because they can be drilled for the repositioned rail spikes. Being difficult to drill, concrete sleepers are less suitable for conversion. Concrete sleepers may be cast with alternative gauge fittings in place, an example being those used during the conversion of the Melbourne–Adelaide railway from to . Steel sleepers may have alternative gauge fittings cast at production, may be drilled for new fittings or may be welded with new fittings.

Structures

Conversion from a narrow to a wider gauge may require enlargement of the structure gauge of the bridges, overpasses and tunnels, embankments and cuts. The

minimum curve radius The minimum railway curve radius is the shortest allowable design radius for the centerline of railway tracks under a particular set of conditions. It has an important bearing on construction costs and operating costs and, in combination with ...

may have a larger

radius In classical geometry, a radius (plural, : radii) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', ...

on broader gauges requiring route deviations to allow the minimum curve radius to be increased. Track centers at

stations Station may refer to: Agriculture * Station (Australian agriculture), a large Australian landholding used for livestock production * Station (New Zealand agriculture), a large New Zealand farm used for grazing by sheep and cattle ** Cattle statio ...

with multiple tracks may also have to be increased. Conversion from narrow to standard gauge can cause several changes not because of the gauge itself, but in order to be compatible with the structure gauge of standard gauge track, such as height of overpasses so that trains can be exchanged. The choice of train couplers may be a factor as well.

Rail vehicles

Where vehicles move to a different gauge, they must either be prepared for bogie exchange or be prepared for wheelset exchange. For example,

passenger train A passenger train is a train used to transport people along a railroad line. These trains may consist of unpowered passenger railroad cars (also known as coaches or carriages) hauled by one or more locomotives, or may be self-propelled; self p ...

s moving between the in France and the gauge in Spain pass through an installation which adjusts their variable-gauge axles. This process is known as "gauge change". Goods wagons are still subject to either bogie exchange or wheelset exchange.

Steam locomotives

Some steam locomotives were constructed to be reconfigured to a different gauge: for example, some

East African Railways The East African Railways and Harbours Corporation (EAR&H) is a defunct company that operated railways and harbours in East Africa from 1948 to 1977. It was formed in 1948 for the new East African High Commission by merging the Kenya and Ugand ...

locomotives;

Garratt A Garratt (often referred to as a Beyer Garratt) is a type of steam locomotive invented by British engineer Herbert William Garratt that is articulated into three parts. Its boiler, firebox, and cab are mounted on a centre frame or "brid ...

s; the large 500, 600 and 700 class locomotives of the

South Australian Railways 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 Aust ...

introduced by William Webb in 1926; and the

Victorian Railways The Victorian Railways (VR), trading from 1974 as VicRail, was the state-owned operator of most rail transport in the Australian state of Victoria from 1859 to 1983. The first railways in Victoria were private companies, but when these companie ...

J, N and R classes. In the Australian instances, conversion was anticipated from broad gauge to standard gauge. Conversion to a wider gauge was similarly anticipated for the large narrow-gauge Western Australian Government Railways V class locomotive (to standard gauge). Of these locomotives, only one R class was converted (when in preservation). Two unanticipated conversions to occur were the ten locomotives of the South Australian Railways 740 class (from standard to broad gauge) and five narrow-gauge T class locomotives, which became the Tx class on the broad gauge before they were eventually converted back again. Gauge-change in steam locomotives has a long lineage. In about 1860, the

Bristol and Exeter Railway The Bristol & Exeter Railway (B&ER) was an English railway company formed to connect Bristol and Exeter. It was built on the broad gauge and its engineer was Isambard Kingdom Brunel. It opened in stages between 1841 and 1844. It was allied with t ...

converted five locomotives to gauge, and later converted them back again. Also in the 19th century, in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

, some broad-gauge locomotives were designed for easy conversion to gauge. In the 20th century, in Victoria station, London, some broad-gauge locomotive classes of the

Great Western Railway The Great Western Railway (GWR) was a British railway company that linked London with the southwest, west and West Midlands of England and most of Wales. It was founded in 1833, received its enabling Act of Parliament on 31 August 1835 and ran ...

were designed for easy conversion to gauge. After

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

, a number of captured German 03 class Pacifics locomotives were re-gauged to the Russian gauge.

Diesel and electric locomotives and trains

Most diesel and electric rolling stock can undergo gauge conversion by replacement of their bogies. Engines with fixed wheelbases are more difficult to convert. In Australia, diesel locomotives are regularly re-gauged between broad, standard and narrow gauges.

Wagons and coaches

Gauge conversion of wagons and coaches involves the replacement of the wheelsets or the

bogie A bogie ( ) (in some senses called a truck in North American English) is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transp ...

s. In May 1892, wagons and coaches were converted when the gauge of the

was abandoned.

Gauge orphan

During or after gauge conversion work, some stations and branch lines may become "gauge orphans". This occurs especially when it is not considered economically worthwhile to go to the expense of gauge conversion. For example, on the standard gauge

line Line most often refers to: * Line (geometry), object with zero thickness and curvature that stretches to infinity * Telephone line, a single-user circuit on a telephone communication system Line, lines, The Line, or LINE may also refer to: Art ...

between Adelaide and Melbourne, the broad gauge Victor Harbor branch line became a gauge orphan after the main line was converted in 1995 because it was too lightly trafficked; it now prospers as a heritage line, SteamRanger.

Notes

References

{{DEFAULTSORT:Gauge Conversion Track gauges