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A dual-gauge railway is a line of track that provides for trains of two separate gauges. A mixed-gauge railway provides for more than two separate gauges, but is also a term sometimes used to denote dual-gauge. A dual-gauge track configuration usually consists of three rails--two 'vital' (or gauge-) rails, one for each gauge, plus a 'common rail'--although at times, commonality is not possible and four rails are required. In a normal 3-rail dual-gauge configuration the two outer rails give the wider gauge, while one of the outer rails and the inner rail give a narrower gauge. The third rail is common to all traffic. This configuration is not to be confused with the electric third rail.
- 1 Reasoning
- 2 Configuration
- 3 Gauge conversion
- 4 Examples
- 5 Four rail dual gauge
- 6 Double dual gauge
- 7 Triple gauge
- 8 Accidents on dual-gauge railways
- 9 Complexity of dual-gauge switches
- 10 Opposition
- 11 Operation and Detection
- 12 Separate gauge
- 13 Platforms
- 14 Overlapping gauges
- 15 Other methods of handling multiple gauges
- 16 Dual gauge dual voltage
- 17 Model railways
- 18 See also
- 19 Notes
- 20 External links
In railways, the most important specification is that of gauge, the distance between the inner surfaces of the heads of the travel rails (see diagram above). Both track and wheels bogies must be built to the same gauge; unless the two fit together within a tolerance of 13 mm (0.5 in.) on the track, the train will either fall off the track or it will be impossible to go through switches or crossovers. For instance, the Hong Kong MTR 1,432 mm (4 ft 8 3⁄8 in)-gauge EMUs may run on KCR 1,435 mm (4 ft 8 1⁄2 in)-gauge rails, with a locomotive or a KCR EMU pulling due to different electrification voltages. A problem arises when different gauges meet one another, a situation known as a break-of-gauge. Either the track or the train must be built to handle different gauges, or passengers and freight must be taken off one train and loaded on to the next.
In allowing railway tracks of different gauges to share the same alignment, costs can be reduced, especially where there are bridges and tunnels. Dual gauge can replace two separate tracks, having two rails each, with one track with three rails. This allows one rail fewer for the stretch of the dual gauge line, but there are complications and costs that may offset the savings.
One issue is points (US: switches). Complicated arrangements are necessary to ensure traffic of both gauges can safely utilise points. Signalling may also be complicated somewhat, as all three rails must be connected to track circuits or mechanical interlocking arrangements. Mixed gauge is simpler to signal with electric signals than with mechanical signals. Since rails wear very slowly, the extra tonnage on the common rail is generally not a problem.
For dual-gauge track to be achievable using three rails, the difference between the gauges needs to be at least as wide as the foot of the rail, otherwise there is no room for the rail fastening hardware (spikes, clips, and the like). Thus standard gauge (1,435 mm/4 ft 8 1⁄2 in) and 1,676 mm (5 ft 6 in) Indian gauge can be dual gauged without problem, as are 914 mm (3 ft) and 1,067 mm (3 ft 6 in) (Cape gauge), or 1,524 mm (5 ft) and 1,829 mm (6 ft), while 1,435 mm (4 ft 8 1⁄2 in) and 1,600 mm (5 ft 3 in) Irish gauge can also be dual-gauged, albeit with lighter narrow footed rails, as in Victoria, Australia. On the other hand, 1,000 mm (3 ft 3 3⁄8 in) metre gauge and 1,067 mm (3 ft 6 in) Cape gauge as in Africa, or 1,000 mm (3 ft 3 3⁄8 in) and 3 ft (914 mm), as in South America, are too close to be combined into three-rail dual gauge, as are 1,435 mm (4 ft 8 1⁄2 in) and 1,524 mm (5 ft), or 1,524 mm (5 ft) and 1,676 mm (5 ft 6 in), as in Afghanistan, Central Asia, northern-, central- and eastern Europe, North America, Iran, and China. This last combination is of particular historical interest, as it was of strategic significance during World War II.
If three-rail dual gauge is impossible (e.g. between 1,435 mm/4 ft 8 1⁄2 in and 1,524 mm/5 ft), four-rail dual gauge has to be used.
The complications and difficulties outlined show how important it is to ensure that railway gauges are standardised in the first place, if at all possible. If a railway operator seeks to convert from one gauge to another, then it helps if a dual-gauge intermediate step can be done (this has often been practised in the past).
Alternatively the rails may be too light for the loads imposed by broader-gauge railcars. Such potential problems can rule out dual-gauge as a feasible option.
Dual-gauge lines in Java were regauged from 4 ft 8 1⁄2 in (1,435 mm) to 3 ft 6 in (1,067 mm) Cape gauge during the Japanese administration in 1942-1943. Regauging occurred only on the relatively short Brumbung-Kedungjati-Gundih main line and the Kedungjati-Ambarawa branch line, as the rest of the line was already dual-gauge (some only recently dual-gauged).
In Los Angeles the 3 ft 6 in (1,067 mm) Los Angeles Railway and the 4 ft 8 1⁄2 in (1,435 mm) Pacific Electric Railway (both defunct) ran on dual gauge track on some downtown streets. The Burlington, Cedar Rapids and Northern Railway (standard gauge) and the Burlington and Northwestern Railway (narrow gauge) shared a dual-gauge mainline from Burlington, Iowa to Mediapolis, 14 miles to the north, between 1880 and 1902. The Colorado and Southern Railway had both standard and narrow gauge trackage, and had dual-gauge track between Denver, Colorado and Golden, until 1941. Similarly, a section of the Denver and Rio Grande Western Railroad's Alamosa-Durango Line from Alamosa, Colorado to Antonito was dual gauge into the 1960s. The East Broad Top Railroad and Coal Company formerly had considerable dual-gauge trackage in its Mount Union, Pennsylvania yard.
Brazil is proposing to build dual gauge track to connect ports in the north east.
Kenya, Uganda and south Sudan: on 12 October 2004, a proposal was announced to develop an electrified rail link connecting Kenya, Uganda and south Sudan. Even though Kenya and Uganda use 1000 mm gauge and Sudan uses 1067 mm, the new project was proposing to use standard gauge (1435 mm). Fortunately, all three gauges can be supported by the same sleepers, as described above.
In Japan, dual gauge is used when standard gauge Shinkansen (Bullet Train) lines joins the narrow-gauge (1,067 mm/3 ft 6 in) system, which is the national standard. For example, part of the Ōu line became part of the Akita Shinkansen and was upgraded to dual gauge.
In Dutch East Indies (later Indonesia), dual-gauge track was installed in 1899 between Yogyakarta and Solo. The track was owned by the Nederlandsch-Indische Spoorweg Maatschappij, a private company, which built the 4 ft 8 1⁄2 in (1,435 mm) gauge line in 1867. The third rail was installed to allow passengers and goods traveling over the 3 ft 6 in (1,067 mm) gauge Staatsspoorweg (State Railway) a direct connection without requiring transfer at both cities. Later, a separate pair of tracks were installed at the government's cost to allow greater capacity and higher speeds.
In 1940 a third rail was installed between Solo and Gundih on the line to Semarang, allowing 3 ft 6 in (1,067 mm) gauge trains to travel between Semarang, Solo and Yogyakarta (via Gambringan, on the line to Surabaya instead of via Kedungjati on the original line).
A short section of dual-gauge 3 ft 6 in (1,067 mm) and 2 ft 5 1⁄2 in (750 mm) line existed in North Sumatra on a joint line of the Deli Railway and the Aceh Tramway. This line survived into the 1970s.
Some sugar mill railways in Java have dual-gauge sections.
A 32km cross-border stretch of track between Russian and North Korea has been rebuilt, starting October 2008, completed in February 2012, as dual-gauge 1,520 mm (4 ft 11 27⁄32 in) Russian gauge and 1,435 mm (4 ft 8 1⁄2 in) standard gauge between Khasan (Russia) and Rajin (North Korea), to allow easier cross-border trains.
In Russia, the railways of Sakhalin Island are to be converted from 1,067 mm (3 ft 6 in) Cape gauge to 1,520 mm (4 ft 11 27⁄32 in) Russian gauge. As the conversion is going to be done in sections, the conversion plans provide for first laying the third (outer) rail, making rail lines usable by both Japanese- and Russian-gauge trains. Once the railways throughout the island have been converted to the Russian gauge (by 2012), the inner rail will be removed.
In Britain, the Great Western Railway was initially broad gauge, 7 ft 1⁄4 in (2,140 mm). After the "gauge war", it was decided to regauge the GWR. As the broad gauge was sufficiently dissimilar from standard gauge and used wooden sleepers, dual gauge was easily introduced. The Metropolitan Railway, now part of the London Underground system, started as dual gauge: its present third and fourth rails are for electricity supply, not dual gauge. A small section of broad gauge, 7 ft 1⁄4 in (2,140 mm) and standard gauge 1,435 mm (4 ft 8 1⁄2 in) demonstration line exists at the Great Western Society site at Didcot.
In Ireland, dual-gauge track was not used in regauging the Ulster Railway (UR). When it regauged its double-track route from 6 ft 2 in (1,880 mm) to the new Irish standard of 5 ft 3 in (1,600 mm) it performed the task in two stages. The Dublin & Drogheda Railway (D&DR) meanwhile was regauging from 5 ft 2 in (1,575 mm), too similar to the new gauge to allow dual gauge. Dual gauge was used in Derry, by the Port Authority, in an on-street network to transfer goods, on either gauge, between the city's four stations (two 3 ft/914 mm narrow gauge, two 5 ft 3 in/1,600 mm in broad gauge).
In Italy, dual-gauge track is used in the Potenza - Avigliano Lucania line, 1,435 mm (4 ft 8 1⁄2 in) and 950 mm (3 ft 1 3⁄8 in).
In Belgium, some sections of tram track in Brussels combined 1,000 mm (3 ft 3 3⁄8 in) metric gauge for the interurban trams with 1,435 mm (4 ft 8 1⁄2 in) standard gauge for the urban trams. Since the closure of the former, these have been replaced with standard gauge track.
In Germany, the Stuttgart tram lines were 1,000 mm (3 ft 3 3⁄8 in) gauge. In the 1970s it was decided to convert the tram system to a modern Stadtbahn and regauge it to standard gauge to increase capacity. Inner-city tunnels replacing street-level sections in busy streets were built with a cross-section suitable for standard-gauge cars. After the conversion started in 1981 with the commissioning of the first three class DT-8 Stadtbahn cars, the tunnels and all other sections used by multiple lines were fitted with 1,435 mm (4 ft 8 1⁄2 in)/1,000 mm (3 ft 3 3⁄8 in) dual-gauge track, to allow both old-style trams and new Stadtbahn cars to share those sections while lines were converted one by one over the next decades. In 2006, conversion of line 15 (the last line to be converted) is under way and was completed in 2008, although some sections will retain their dual-gauge track indefinitely as a courtesy to the tram museum of Stuttgart, which will operate old 1,000 mm (3 ft 3 3⁄8 in) gauge trams on weekends and special occasions.
Also in Germany, in Krefeld on Ostwall the tram lines are dual-gauge track, to allow both standard 1,435 mm (4 ft 8 1⁄2 in) Rheinbahn U76 Stadtbahn cars to share this section with Krefeld's metre 1,000 mm (3 ft 3 3⁄8 in) gauge. At the north end of the street at the junction with Rheinstraße, Rheinbahn trams reverse, so the standard gauge ends, while the metre gauge lines continue. The dual-gauge track continues along Oppumer Straße in front of Krefeld Hauptbahnhof (Main Rail Station), where at both ends of this street, the metre 1,000 mm (3 ft 3 3⁄8 in) and standard 1,435 mm (4 ft 8 1⁄2 in) tracks diverge.
In Switzerland dual gauge track (1,435 mm/4 ft 8 1⁄2 in standard and 1,000 mm/3 ft 3 3⁄8 in metric) is used in (Lucerne and Interlaken) stations at both ends of the Brünigbahn and on the RhB between Chur and Domat Ems (see first illustration of this article), among other places.
In Sweden and Finland, there is 2 km of dual gauge, 1,435 mm (4 ft 8 1⁄2 in) and 1,524 mm (5 ft), between Haparanda and Tornio across the bridges over the border. At each end of the dual-gauge section there are yards with standard and Finnish gauge areas to allow for trans-shipment. The four-rail method is used because the gauges are close together. The bridge structure needs to be wider than normal to allow for the offset from the centreline by each gauge. At the Tornio yard is a Rafil gauge changer. Similar arrangements exist on the approach to Kaliningrad, where 1,435 mm (4 ft 8 1⁄2 in) track penetrates from the Polish border with some dual gauge stretches.
In Sweden there also is a 891 mm (2 ft 11 3⁄32 in) and 1,435 mm (4 ft 8 1⁄2 in) dual gauge between Västervik and Jenny. In Västervik there also is dual gauge in the station area.
In Spain, there is dual gauge in the AVE line from Zaragoza to Huesca, usable for both 1,435 mm (4 ft 8 1⁄2 in) standard gauge high speed trains and 1,668 mm (5 ft 5 21⁄32 in) Iberian gauge Spanish trains. In 2009, Adif called for tenders for the installation of a third rail for standard gauge trains on the 22 km (14 mi) between Castellbisbal and the Can Tunis freight terminal in Barcelona.
In Western Australia there is a double-track dual-gauge (3 ft 6 in/1,067 mm & 4 ft 8 1⁄2 in/1,435 mm) main line from East Perth to Northam, about 120 km. Dual-gauge track is also used from the triangle at Woodbridge to Cockburn Junction, then to Kwinana on one branch, and North Fremantle on the other.
In Brisbane, Australia, shorter stretches of dual-gauge track (3 ft 6 in/1,067 mm & 4 ft 8 1⁄2 in/1,435 mm) exist between the rail freight yards at Acacia Ridge and the Port of Brisbane, for freight trains. A dual-gauge line branches off at Park Road Station to run alongside the electric suburban narrow gauge Citytrain line over the Merivale Bridge into Platform 1 at Roma Street Station. This is used by standard-gauge interstate NSW TrainLink XPT services to Sydney.
In 2012, dual gauge was installed between Acacia Ridge and Bromelton to serve a new freight hub at the latter station.
The new port of Oakajee was previously to be served by separate narrow gauge and standard gauge lines, but Westnet, the track authority, has proposed a common network with a significant length of double track dual gauge, which has greater flexibility.
Four rail dual gauge
If the difference between two gauges is too small, such as between 1,000 mm (3 ft 3 3⁄8 in) and 1,067 mm (3 ft 6 in), then four rails must be used to make practical dual gauge.
Four rails may also be needed where it is desirable to co-locate the track centres of the two gauges, such as might happen through tight tunnels or through platforms. Roma Street, Queensland, uses both three rail and four rail dual gauge between 1,435 mm (4 ft 8 1⁄2 in) and 1,067 mm (3 ft 6 in).
Double dual gauge
In Australia, the new railway line between Perth and Northam was being planned in the 1960s. The improved alignment was originally intended to have separate standard gauge and narrow gauge tracks running parallel, with crossing loops at intervals. However, the capacity of each of these lines would have been poor. By adopting double-track dual-gauge throughout, the line capacity was greatly increased, at only the relatively small extra cost of providing a third rail was needed for dual gauge.
There have been a few instances of triple-gauge break-of-gauge stations.
|Area||Gauge 1||Gauge 2||Gauge 3||Note|
|Port Pirie, South Australia||1,067 mm (3 ft 6 in)||1,435 mm (4 ft 8 1⁄2 in)||1,600 mm (5 ft 3 in)||1938–1970|
|Gladstone, South Australia||1,067 mm (3 ft 6 in)||1,435 mm (4 ft 8 1⁄2 in)||1,600 mm (5 ft 3 in)||1968-1980s|
|Peterborough, South Australia||1,067 mm (3 ft 6 in)||1,435 mm (4 ft 8 1⁄2 in)||1,600 mm (5 ft 3 in)||1968-1980s some survives in the Steamtown Heritage Rail Centre|
|Latour-de-Carol, France||1,000 mm (3 ft 3 3⁄8 in)||1,435 mm (4 ft 8 1⁄2 in)||1,668 mm (5 ft 5 21⁄32 in)||still in use|
|Hendaye, France||1,000 mm (3 ft 3 3⁄8 in)||1,435 mm (4 ft 8 1⁄2 in)||1,668 mm (5 ft 5 21⁄32 in)||still in use|
|Växjö, Sweden||891 mm (2 ft 11 3⁄32 in)||1,067 mm (3 ft 6 in)||1,435 mm (4 ft 8 1⁄2 in)||until at least 1974|
|Montreux, Switzerland||800 mm (2 ft 7 1⁄2 in)||1,000 mm (3 ft 3 3⁄8 in)||1,435 mm (4 ft 8 1⁄2 in)||still in use|
|Capolago, Switzerland||800 mm (2 ft 7 1⁄2 in)||1,000 mm (3 ft 3 3⁄8 in)||1,435 mm (4 ft 8 1⁄2 in)||the metre gauge line closed in 1950|
|Volos, Greece||600 mm (1 ft 11 5⁄8 in)||1,000 mm (3 ft 3 3⁄8 in)||1,435 mm (4 ft 8 1⁄2 in)||600 mm gauge closed on 70s, 1000 mm gauge closed on 1998|
|Toronto, Canada||1,067 mm (3 ft 6 in)||1,435 mm (4 ft 8 1⁄2 in)||1,676 mm (5 ft 6 in)||Converted to 1,435 mm (4 ft 8 1⁄2 in) gauge|
Because these three triple-gauge examples were yards operating at low speed, light rail could be used to space the rails closely together if required. Main line operation at high speeds is another matter.
The Niagara Falls Suspension Bridge originally carried trains of three different gauges.
The National Railway Museum (Port Adelaide) in Adelaide, Australia has the three main-line gauges and a 18 in (457 mm) gauge tourist line.
The EMD locomotive plant in McCook, Illinois maintained a small amount of multi-gauge track with up to seven parallel rails in 1960s and 70's to support the wide variety of export locomotives they produced. This track did include a turnout splitting a standard gauge track off of the seven-rail track, requiring 8 frogs in a row.
Accidents on dual-gauge railways
On September 9, 2004, an accident happened on a switch in Jindřichův Hradec, Czech Republic where a dual-gauge railway bifurcates. A Junák express from Plzeň to Brno derailed due to a signalling error. The standard gauge train was switched onto the narrow gauge track. The express train driver was slightly injured.
In Western Australia, the signalling system detects the gauge of the approaching trains and puts the signals to stop if the route is set for the wrong gauge. This is easier to do if the signalling is electrical rather than mechanical.
Complexity of dual-gauge switches
Dual-gauge turnouts (also known as switches or points), where both gauges have a choice of routes, are quite complicated, with more moving parts than single-gauge turnouts. They impose very low speed limits. If dual-gauge points are operated and detected by electrical circuits, their reliability will be high.
Where two gauges separate (i.e. each gauge has only one route, as in the picture at right), few if any moving parts are needed.
Third-rail was proposed around 1900 as a solution for the break of gauge problems in Australia, but there was a problem with the design of turnouts due to the closeness of standard gauge and irish gauge of only 6.5 inches. After one or two decades on increasing rancour, the dual gauge option was rejected as unacceptable, especially the Brennan dual gauge switch.
However, where the difference between the gauges is large, say 14.5 inches between 1,067 mm (3 ft 6 in) and 1,435 mm (4 ft 8 1⁄2 in), dual gauge is not a problem, as evidenced by 45 years of successful operation in Western Australia.
In Australia, after a brief period of support, dual gauge between 1,600 mm (5 ft 3 in) gauge and 1,435 mm (4 ft 8 1⁄2 in) gauge came to be vehemently opposed, even with the Brennan switches, mainly because of hazard of the narrow gap between the outer.
For good measure, dual gauge between 1,600 mm (5 ft 3 in) gauge and 1,067 mm (3 ft 6 in) gauge was also opposed, even though the gap is much bigger.
Operation and Detection
The separate ends of dual gauge turnouts are easier to arrange if the ends are electrically operated rather than mechanically operated.
If the two gauges of a dual gauge turnout are very similar and the difference between them is small, turnouts will have many small pieces that are difficult to support and the turnout will be weak and limited in speed. Paradoxically, the larger the difference the better. The difference between the gauges should as a rule of thumb be 50 mm greater than the width of the base of the rails. The difference between standard and East European/Russian gauge is too narrow.
One way of avoiding complicated and weak dual gauge turnouts, provided there is room, is to separate the gauges and then design the yard with single gauge turnouts and dual gauge diamond crossings. Gauge splitters assume that trains have a single gauge. Gauge splitters may be fixed, meaning they have no moving parts and are intended for low speed use, or they be power operated like ordinary turnouts.
If dual-gauge turnouts are too slow, or too difficult because the gauges are too similar, then an option is to build two separate lines, one of each gauge, side by side. This choice also depends on the amount of traffic. Dual-gauge could continue to be employed at an expensive bridge or tunnel.
Separate lines can at least share signal boxes, signallers and other major infrastructure.
- Albury, New South Wales to Melbourne, Victoria, 300 km
- Melbourne Victoria, to Geelong, Victoria, 80 km, a single standard-gauge line parallel to double-track broad gauge.
- Yogyakarta-Solo in Java, Dutch East Indies during pre-WW II days, 58 km. This had a single 3 ft 6 in (1,067 mm) line parallelling a dual-gauge 4 ft 8 1⁄2 in (1,435 mm) and 3 ft 6 in (1,067 mm) line.
- Australia - in 1960, the Perth to Northam line was originally to be separate side-by-side narrow gauge and standard gauge lines, but it was realised that line capacity would be much higher if it were built as double dual gauge.
- The Uzhhorod – Košice broad gauge track will in 2016 be extended 450 km to Austria parallel to a normal gauge railway.
Low level platforms are not a problem with dual gauge trains, since carriages are always higher than the platforms. With third rails and high level platform, one gauge may be too close or too far away, depending on which side the third rail is. In Western Australia, between Midland and Perth Terminal Terminal, the problem does not in practice arise, because the standard gauge trains do not stop at the intermediate stations.
Bangladesh is tackling its break of gauge problem by adding a third rail to its broad and narrow gauge lines, so that it becomes a mainly dual-gauge system. The new Jamuna Bridge that links the east and west rail systems is four rail dual gauge. At some stage the government of Bangladesh may choose one gauge over the other and convert to a single gauge, but there are no immediate plans for this.
Bangladesh's neighbour to the east is also 1000 mm gauge, should the missing link ever be built.
A variation of overlapping gauge is to extend a railway of one gauge into territory that is mainly of another gauge so as to avoid transhipment of specific traffic. For example a 1524 mm gauge line runs from an iron ore mine in Ukraine to a steelworks in Slovakia, and now may be extended into Austria.
Other methods of handling multiple gauges
Other methods of handling multiple gauges include:
- Transporter wagons or transporter trucks, which carry equipment of one gauge on the other's tracks. This can be also done by the trainload. Bridges and tunnels need to be about one metre higher than they would otherwise be.
- Bogie exchange systems, where the railroad car is lifted and the trucks/bogies under it are swapped. This system is not suitable for four-wheel wagons.
- Adjustable gauge equipment (variable gauge axles), in which the wheel gauge can be widened or narrowed.
- Transshipment, where containers or people are transferred from one set of railroad cars to another.
Dual gauge dual voltage
- Central line to have standard gauge?[dead link]
- The length of Vietnam railway network[dead link]
- Russian Railways : Demonstration train makes run between Rajin and Khasan
- Сахалинская узкоколейная железная дорога (The narrow-gauge railways of Sakhalin) (Russian)
- The mixed-gauge track has length about 2 km. Initially there were four rails, in 1985 it was converted to three rails. See Czech Wikipedia articles Jindřichův Hradec - Nová Bystřice Railway and Frýdlant v Čechách - Heřmanice Railway.
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- "SOUTH AUSTRALIA.". The Sydney Morning Herald (NSW : 1842 - 1954) (NSW: National Library of Australia). 6 September 1889. p. 8. Retrieved 11 November 2011.
- "Roma Street gauge splitter". Gallery.qrig.org. Retrieved 2012-09-24.
- "3-Rail, 4-Rail and transition". Gallery.qrig.org. Retrieved 2012-09-24.
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- Jane's World Railways (hard copy)
- Jindřichův Hradec Local Railways
- Jindřichohradecké úzké mainly in Czech language
- South Australia - Rail Revitalisation Project
- Columbus' Streetcar Track Gauge
- Diagram of mixed gauge turnouts