Track gauge conversion

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"Change of gauge" redirects here. For other uses, see Change of gauge (disambiguation).
See also: Dual gauge
Track gauge
By transport mode
Tram · Rapid transit
Miniature · Scale model
By size (list)
Graphic list of track gauges

  Fifteen inch 381 mm (15 in)

  600 mm,
Two foot
594 mm
597 mm
600 mm
603 mm
610 mm
(1 ft 11 14 in)
(1 ft 11 12 in)
(1 ft 11 58 in)
(1 ft 11 34 in)
(2 ft)
  750 mm,
Two foot six inch,
800 mm
750 mm
760 mm
762 mm
800 mm
(2 ft 5 12 in)
(2 ft 5 1516 in)
(2 ft 6 in)
(2 ft 7 12 in)
  Swedish three foot,
900 mm,
Three foot
891 mm
900 mm
914 mm
(2 ft11 332 in)
(2 ft 11 716)
(3 ft)
  Metre 1,000 mm (3 ft 3 38 in)
  Three foot six inch,
Cape, CAP, Kyōki
1,067 mm (3 ft 6 in)
  Four foot six inch 1,372 mm (4 ft 6 in)

  Standard 1,435 mm (4 ft 8 12 in)

Five foot
1,520 mm
1,524 mm
(4 ft 11 2732 in)
(5 ft)
  Irish 1,600 mm (5 ft 3 in)
  Iberian 1,668 mm (5 ft 5 2132 in)
  Indian 1,676 mm (5 ft 6 in)
  Six foot 1,829 mm (6 ft)
  Brunel 2,140 mm (7 ft 14 in)
Change of gauge
Break-of-gauge · Dual gauge ·
Conversion (list· Bogie exchange · Variable gauge
By location
North America · South America · Europe · Australia
World map, rail gauge by region

In rail transport, gauge conversion is the process of converting a railway from one rail gauge to another, through the alteration of the railway tracks. An alternative to gauge conversion is dual gauge track, or gauge conversion of the rail vehicles themselves.

Ideally railways should all be built to the same gauge, since a wide range of gauges from narrow to broad are of similar value in carrying heavy loads at low cost, while small differences of gauge create tremendous break-of-gauge costs and inconvenience.

Permanent way[edit]


Rails may be too light for the loads imposed by broader-gauge railcars and need to be replaced with a heavier rail profile.

Sleeper types[edit]

If the conversion involves the track gauge being narrowed, the existing sleepers can often continue to be used, but if the gauge is being increased, the sleepers used for the narrower gauge may be too short, and need to be replaced with longer ones.

In some cases, gauge-convertible sleepers are installed before the conversion of the track itself. The sleepers must be long enough to take the wider of the two gauges, and must be able to accommodate the fittings for both the existing and the new gauges. In cases where the difference between the two gauges is small, such as 1,000 mm (3 ft 3 38 in) and 1,067 mm (3 ft 6 in) track, or 1,435 mm (4 ft 8 12 in) and 1,524 mm (5 ft) track, providing dual-gauge track using a third rail is not practicable. In those cases, gauntlet track is required.

  • Timber sleepers are always gauge convertible, provided that they are long enough, because new holes for the repositioned dogspikes can be drilled into them. If the new gauge is wider than the old, a shorter sleeper than would normally be used can be tolerated, provided it still allows for secure fastening of the wider track.
  • Concrete sleepers cannot be converted as an afterthought, but must have the future fittings cast in place when manufactured.
  • Steel sleepers should have the extra fitting incorporated when manufactured, though it is theoretically possible to drill or weld new fittings to the sleeper after installation.

During the conversion of the Melbourne–Adelaide railway in Australia from 5 ft 3 in (1,600 mm) to 4 ft 8 12 in (1,435 mm), dual-gauging of the track was not possible because the foot of the heavy rails being used was too wide to allow them to be placed sufficiently close together. A special gauge-convertible sleeper, with a reversible chair for the Pandrol clip, allowed a two-week conversion process.

In June 2008, the South Australian government announced that by 2012 the Adelaide metropolitan network would be converted from 1,600 mm broad gauge to standard gauge.[1] Consequently, broad-gauge timber sleepers are progressively being replaced with gauge-convertible concrete sleepers on the metropolitan rail network. As of 2016, however, gauge conversion had not commenced, and financial constraints seem likely to delay the program for the foreseeable future.

Structure gauge[edit]

Narrow-gauge railways often have a significantly smaller structure gauge, and therefore the rolling stock used has a smaller loading gauge in both height and width. Conversion to a wider track gauge will often require enlargement of the structure gauge on bridges, under road overpasses and in tunnels. Embankments and cuts could need widening as well.

The minimum curve radius of narrow-gauge railways is often less than on tracks with a wider gauge, so route deviations might be required to allow the radius of curves to be increased. Track centres at stations with multiple tracks may also have to be increased.

Gauge orphan[edit]

During gauge conversion work such as between Seymour and Albury, branch lines such as Benalla to Oaklands and stations such as Violet Town become gauge orphans as they cannot easily be served by trains until extra costly work is done.

In this instance, the loading gauge of the broad gauge and standard gauge lines are essentially the same.

Rolling stock[edit]

Where vehicles cross a change of gauge, they must either be equipped for a change of bogie or have adjustable gauge axles. For example passenger trains crossing between the 1,435 mm (4 ft 8 12 in) system in France and the 1,668 mm (5 ft 5 2132 in) in Spain pass through a special installation which adjusts their variable gauge axles. This temporary alteration to allow through working is generally referred to as "gauge change".



Steam locomotives are difficult to convert unless this is already allowed for in the design, such as in some East African Railways Garratts, and in steam locomotives built for Victoria after the 1930s. In the event, few have been so converted, but one such is Victorian Railways R class R766.

Because boilers and fireboxes are in the way (unless allowed for) locomotives can be converted only to a wider gauge.

About 1860, the Bristol and Exeter Railway converted five 1,435 mm (4 ft 8 12 in) gauge locomotives to 7 ft (2,134 mm) gauge, and later converted them back again.

In the 19th century, in the US, some broad 1,524 mm (5 ft) gauge locomotives were designed for easy conversion to 1,435 mm (4 ft 8 12 in) gauge.

In the 20th century, in Victoria, some broad 1,600 mm (5 ft 3 in) gauge locomotive classes were designed for easy conversion to the narrower 1,435 mm (4 ft 8 12 in) gauge.

Between 1922 and 1949, five South Australian Railways T class narrow 1,067 mm (3 ft 6 in) gauge locomotives were converted to Tx-class broad 1,600 mm (5 ft 3 in) gauge, and later back again.

In 1941, there were plans to regauge 1,435 mm (4 ft 8 12 in) gauge steam locomotives to the 1,524 mm (5 ft) gauge.[2]

Post WWII, a number of captured German 03 class pacifics were regauged to the Russian gauge.

Diesel & electric[edit]

Most diesel and electric which rest on bogies can be converted by replacing those bogies. Engines with fixed wheelbases are problematic.

In Australia, diesel locomotives are regularly regauged between broad, standard and narrow gauges.

Waggons and carriages[edit]

Gauge conversion of coaches and wagons involves the replacement of the wheelsets or entire bogies, such as happened when the 7 ft 14 in (2,140 mm) gauge of the Great Western Railway was abandoned in May 1892.


During WWI and WWII, gauge conversion occurred backwards and forwards between Germany and Russia as the Eastern Fronts of WW I, Eastern Fronts of WW II and national borders changed.

  • India India conversion of 17,000 km (11,000 mi) of 1,000 mm (3 ft 3 38 in) metre gauge to 1,676 mm (5 ft 6 in) broad gauge under project Unigauge
  • Australia Melbourne to Adelaide - 600 km (370 mi) of convertible sleepers installed in 1990 to facilitate quick conversion in 1995.
  • Australia Adelaide - convertible sleepers installed should gauge conversion be needed in future.
  • Nigeria Port Harcourt - Onne, Nigeria - convertible sleepers installed since gauge conversion not imminent.
  • Australia The Mount Gambier line in South Australia was fitted with some 3-gauge steel sleepers when it was "temporarily" converted from 1,067 mm (3 ft 6 in) to 1,600 mm (5 ft 3 in) in the 1950s, pending later proposed conversion to 1,435 mm (4 ft 8 12 in) which is yet to occur.
  • Central Asia - while China China and Europe Europe are connected by rail, and while both are mainly 1,435 mm (4 ft 8 12 in), the intervening Central Asia Railways are 1,520 mm (4 ft 11 2732 in) gauge. Intervening lines are gradually being made gauge convertible[citation needed] to facilitate an eventual linkage of the Chinese and European standard gauge system. (variable gauge trains)
  • Tanzania Tanzania in 2008 is proposing 1,000 mm (3 ft 3 38 in)/1,067 mm (3 ft 6 in) steel sleepers and 1,000 mm (3 ft 3 38 in)/1,435 mm (4 ft 8 12 in) concrete sleepers to suit gauge conversion.

Conversions to Broad Gauge[edit]

Conversions to Indian Broad Gauge[edit]

  • India India conversion of 17,000 km (11,000 mi) of 1,000 mm (3 ft 3 38 in) metre gauge to 1,676 mm (5 ft 6 in) broad gauge under project Unigauge
  • Bangladesh Bangladesh dual gauge of main lines formerly metre gauge to 1,676 mm (5 ft 6 in) broad gauge. New lines are built either as broad gauge or dual gauge. [3]
  • NepalNepal The Jaynagar to Janakpur narrow gauge line is under gauge conversion to 1,676 mm (5 ft 6 in) broad gauge.
  • PakistanPakistan Metre and narrow gauge rail lines have been gauge converted to 1,676 mm (5 ft 6 in) broad gauge or diamantled or abandoned.
  • Sri LankaSri Lanka 1992 Kelani Valley rail line was converted from 762 mm (2 ft 6 in) narrow gauge to 1,676 mm (5 ft 6 in) broad gauge

Conversions to standard gauge[edit]

  • Australia 1970 Indian Pacific
    • Victoria (Australia) The Seymour - Albury section (~200 km or 120 mi) of the Victorian North East railway line was converted to standard gauge from 1,600 mm (5 ft 3 in) in 2010, creating a double track 1,435 mm (4 ft 8 12 in) route for increasing interstate traffic. The freight-only 1,600 mm (5 ft 3 in) Oaklands branchline was also converted. The cost of converting this 126 km (78 mi) line has been estimated as just over $13m.[4]
  • Canada 1881 Toronto, Grey and Bruce Railway from 1,067 mm (3 ft 6 in) to 1,435 mm (4 ft 8 12 in)
  • Germany 1941 Brest-Minsk[5]
  • Germany 1964/65 Zabergäu Railway 750 mm (2 ft 5 12 in) to 1,435 mm (4 ft 8 12 in)
  • Peru Peru from Huancayo to Huancavelica from 914 mm (3 ft) to 1,435 mm (4 ft 8 12 in); 147 km (91 mi).[6] completed 2009.
  • Spain Spain is building its High Speed lines to 1,435 mm (4 ft 8 12 in) gauge, even though the existing system is 1,668 mm (5 ft 5 2132 in); new cutoff lines are being built with gauge convertible sleepers for easy conversion to standard gauge when required.
  • United States The Congressional act of March 3, 1863 (12 Sta. 807),[7] entitled "AN ACT to establish the gauge of the Pacific railroad and its branches." set the standard for the First Transcontinental Railroad and its branches, thus encouraging previously laid railroads to regauge, allowing for transcontinental shipment. Southern railroads, due to the American Civil War, were not converted until May 31- June 1, 1886 when they were respiked from 5 ft (1,524 mm) gauge to 4 ft 9 in (1,448 mm) - functionally compatible with standard gauge. The final conversions to true standard gauge took place gradually as track was maintained.[8]


  • Sierra Leone Port Pepel iron ore line, from derelict 1,067 mm (3 ft 6 in) to 1,435 mm (4 ft 8 12 in)[9]

Conversion to Cape Gauge[edit]

Integrated with Southern African railways[edit]

  • Beria - Salisbury - 1910 - was 610 mm (2 ft)
  • Namibian Railways, 1930s, much of which was 610 mm (2 ft)


  • Matadi–Kinshasa Railway - 1932 - was 762 mm (2 ft 6 in) ; mostly new alignment
  • Luanda Railway, Angola, was 1,000 mm (3 ft 3 38 in)
  • Angola Namibe Railway, 1950s, was 600 mm (1 ft 11 58 in)
  • Kindu (Lualaba River port) - Kibombo – Kongolo – Kabalo (Lualaba River port and junction with Katanga Line) - Nyunzu – Niemba – Kalemie (the port on Lake Tanganika), 1,067 mm (3 ft 6 in). This line was isolated 1,000 mm (3 ft 3 38 in) until 1955, when the gauge was changed for the connection with the Katanga line in 1956.

Conversion to metre gauge[edit]

From 1920, the standard gauge part of the Siam railway amounting to 1,000 km (620 mi) was converted first to third rail, and then to 1,000 mm (3 ft 3 38 in) (metre gauge) making the whole system metre gauge.[10]

Conversion rate[edit]

Variable gauge axles[edit]

Gauge conversion may become less important with the development of a number of different variable gauge axle systems, also called Automatic Track Gauge Changeover Systems, such as the SUW 2000.

See also[edit]