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A dual-gauge railway is a line of track that provides for trains of two separate track 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 (the two separate tracks of each gauge are placed within each other). In an ordinary three-rail dual-gauge configuration, the two adjacent outer rails give provide each of the gauges, while the single outer rail is common to trains of both gauges operating over it. This configuration is not to be confused with the electric current traction rail (third rail) or a check or guard rail.
In railways, the most important specification is that of rail gauge, the distance between the inner surfaces of the heads of the travel rails. Both track and wheel bogies must be built to the same gauge; unless the two fit together within a typical 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. However, there is a small tolerance; for example, 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 (but not vice versa), with a locomotive or a KCR EMU pulling due to different electrification voltages. Another example would be Finno-Russian border: when in the Seventies the Soviet Union redefined the breadth of a Russian gauge from the traditional five feet (1524 mm) to exactly 1520 mm, the Finnish railways stuck with the old value. This did not result in the break-of-gauge because no actual track work was done, as the redefinition was more of a change in the way the tolerances were counted, both railways remained well within tolerances of each other, and several years later Finland also tightened tolerances much the same way as the USSR did, but without the change to the nominal gauge.
A problem arises when different gauges outside of this tolerance 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 transfer between different trains, or in some instances, the rolling stock is lifted and the bogies are removed and replaced with different bogies for the other gauge.
In allowing railway tracks of different gauges to share the same alignment, costs can be reduced, and infrastructure shared, e.g. platforms, bridges and tunnels etc. Dual gauge can replace two separate tracks by sharing one common running rail and one of the two other outer rails which determine the gauge.
However, there are some complications and costs involved that may offset the savings. One issue is that points (US: switches) are more complex, and therefore more expensive. Arrangements are necessary to ensure trains of both gauges can be safely signalled, track circuits and mechanical interlocking where provided must be operated through the common rail. Also, the common rail will have an increased wear and tear over the other separate gauge rails.
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). The follow pairs of gauges can be dual-gauged without problem: standard gauge (1,435 mm (4 ft 8 1⁄2 in)) and 1,676 mm (5 ft 6 in), 3 ft (914 mm) and 3 ft 6 in (1,067 mm), and 5 ft (1,524 mm) and 6 ft (1,829 mm). Standard gauge (1,435 mm (4 ft 8 1⁄2 in)) and 1,600 mm (5 ft 3 in) can also be dual-gauged, albeit with lighter, narrow-footed rails, as done in Victoria, Australia.
On the other hand, many pairs of gauges are too close to be combined into three-rail dual-gauge, such as 1,000 mm (3 ft 3 3⁄8 in) metre gauge and 3 ft 6 in (1,067 mm), common in Africa; 1,000 mm (3 ft 3 3⁄8 in) and 3 ft (914 mm), common in South America; and 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), common in Afghanistan, Central Asia, northern-, central- and eastern Europe, Russia, 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 gauntlet track dual-gauge has to be used, this was the case in the construction of the Rail Baltica project.
The complications and difficulties outlined illustrate the benefits of standardised railway gauges, where possible. Frequently, a railway operator has changed from one gauge to another via a period of dual gauge operations, e.g. in the UK, the GWR (reluctantly) accepted that it would need to convert from the 7 foot broad gauge to the standard gauge for ease of inter company traffic and had a significant period and network of dual gauge operations. Also, during that period of foreseen change all new rolling stock and locomotives were built in a manner that would allow ease of gauge conversion from broad gauge to standard gauge.
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, unless heavier rails are installed.
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) 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 (23 km) 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.
Alaska and British Columbia are proposing dual gauge, 1,435 mm (4 ft 8 1⁄2 in) standard gauge and 914 mm (3 ft), track so that a narrow gauge tourist train and standard gauge ore trains can share the right of way.
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 1,000 mm (3 ft 3 3⁄8 in) gauge and Sudan uses 1,067 mm (3 ft 6 in), the new project was proposing to use standard gauge (1,435 mm (4 ft 8 1⁄2 in)). 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 join the narrow-gauge (1,067 mm (3 ft 6 in)) system, which is the national standard. For example, part of the Ōu Main Line became part of the Akita Shinkansen and was converted 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 750 mm (2 ft 5 1⁄2 in) 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 2 km (1.2 mi) cross-border stretch of track between Russia 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 3 ft 6 in (1,067 mm) 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 the Czech Republic, there is dual gauge (1,435 mm or 4 ft 8 1⁄2 in standard gauge and 760 mm or 2 ft 5 15⁄16 in) track near Jindřichův Hradec. The two gauges are used by different railway companies.
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 short 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 France, the Chemin de Fer de la Baie de Somme is dual gauge between Noyelles-sur-Mer and Saint-Valery-sur-Somme, metre gauge laid within standard gauge, thus having four rails.
In Belgium, some sections of tram track in Brussels combined 1,000 mm (3 ft 3 3⁄8 in) metre 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 1,000 mm (3 ft 3 3⁄8 in) metre 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.
The same happens within the city of Mülheim where Duisburg tram line 901 meets the local line 102. The tram system in Duisburg is operated on 1,435 mm (4 ft 8 1⁄2 in) while the grand tram system spanning from Witten to Mülheim has 1,000 mm (3 ft 3 3⁄8 in) tracks. Lines 102 and 901 share a tunnel section between Mülheim (Ruhr) Hauptbahnhof (main station) to Schloss Broich, and shortly after the tracks rise to street level, the lines diverge.
Originally the biggest tram system in the world span from Werne to Bad Honnef and consisted of various operators and gauges. The tram system in Wuppertal was made up of 1,435 mm (4 ft 8 1⁄2 in) east-west lines and 1,000 mm (3 ft 3 3⁄8 in) north-south lines. Also, the system in Duisburg had 1,435 mm (4 ft 8 1⁄2 in) lines south of the river Ruhr and 1,000 mm (3 ft 3 3⁄8 in) north of it. In the 1960s and 70s most of the routes north of the river the closed and two remaining main routes converted to 1,435 mm (4 ft 8 1⁄2 in). Today, there are three 1,435 mm (4 ft 8 1⁄2 in) lines in Duisburg.
In Greece, the line between Athens and Elefsis (now closed) was dual gauge in order to allow the 1,000 mm (3 ft 3 3⁄8 in) gauge trains of the Peloponesian rail network to pass, but also to allow standard gauge trains to reach the Elefsis Shipyards. In Volos, a short section of tracks between the main station and the harbour used an almost unique triple gauge, to accommodate standard gauge trains from Larissa, metre gauge from Kalambaka, and the 600 mm gauge trains of the Pelion railway.
In Switzerland dual gauge track (1,435 mm or 4 ft 8 1⁄2 in standard and 1,000 mm or 3 ft 3 3⁄8 in metre gauge) is used in (Lucerne and Interlaken) stations at both ends of the Brünigbahn and on the RhB between Chur and Domat/Ems (see second illustration of Europe gallery below), among other places.
In Sweden and Finland, there is 2 km (1.2 mi) 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 (21,7 km). 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.
Sunlight reflects off dual-gauge tracks near Chur, Switzerland
In Jenny, Sweden, the narrow gauge leaves the standard gauge
Residual dual gauge track on the Voies Ferrées du Dauphiné in France.
In Victoria there are sections of dual gauge (5 ft 3 in (1,600 mm) & 4 ft 8 1⁄2 in (1,435 mm)) between Southern Cross station and West Footscray, Sunshine and Newport, Albion and Jacana, North Geelong and Gheringhap, Maryborough and Dunolly, and in various goods yards and industrial sidings. There was previously dual gauge between Wodonga and Bandiana until the line was closed in 2008.
In New South Wales there was dual gauge (5 ft 3 in (1,600 mm) & 4 ft 8 1⁄2 in (1,435 mm)) within Albury railway station prior to the broad gauge being converted to standard gauge in 2011. There is dual gauge within Tocumwal railway station although the standard gauge has been out of use since 1988.
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 (75 mi). 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 Queensland, there is a section of dual gauge track (3 ft 6 in (1,067 mm) & 4 ft 8 1⁄2 in (1,435 mm)) between the rail freight yards at Acacia Ridge and Park Road Station utilised by both passenger and freight trains. Freight trains to the Port of Brisbane utilise a dual gauge section that parallels the Cleveland railway line from Park Road to Lytton. Passenger trains utilise the dual gauge section of the Beenleigh railway line paralleling the electric suburban narrow gauge Queensland Rail City network line over the Merivale Bridge into Platforms 1 and 2 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.
Dual broad and standard gauge track at North Geelong, Victoria.
Dual gauge track in Melbourne, Victoria. Note guard rails which force standard-gauge trains to change side.
Dual gauge track in Perth, Western Australia. Narrow gauge train on left; Standard gauge train on right.
Tracks are separating for island platform used only by narrow gauge electric trains.
A2 Set 47 accelerates out of Success Hill en route to Midland on dual gauge track.
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).
Four rail dual gauge gallery
The railway bridge over the Swedish-Finnish border has four rails to create a dual gauge track. As the difference between gauges is mere 89 mm (3.5 in), a three rail solution wouldn't provide enough room for flanges between the unshared rails, not to mention the bottom flanges of the unshared rails.
Metre gauge within standard gauge
A metre gauge point within standard gauge track, Chemin de Fer de la Baie de Somme, France
Four rail track with a complicated switch on the Chemin de Fer de la Baie de Somme.
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 that 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|
|Jenbach, Austria||760 mm (2 ft 5 15⁄16 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 (1 ft 11 5⁄8 in) gauge closed in the 1970s, 1,000 mm (3 ft 3 3⁄8 in) gauge closed in 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|
|The Niagara Falls Suspension Bridge, Canada / US||4 ft 8 1⁄2 in (1,435 mm)|
New York Central Railroad
|5 ft 6 in (1,676 mm)|
Great Western Railway
|6 ft (1,829 mm)
|The 6 ft (1,829 mm) was never built through bridge into Canadian section due to obstacles.|
Converted to 4 ft 8 1⁄2 in (1,435 mm) in the 1870s
Because all these triple-gauge examples were, with the exception of the Niagara Falls Suspension Bridge, 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.
Within a works facility or maintenance yard, tracks consisting of four or more separate gauges may be used. At Alan Keef in Lea, Herefordshire a short section of line uses four rails to allow locomotives of 2 ft (610 mm), 2 ft 6 in (762 mm), 3 ft (914 mm) and 3 ft 6 in (1,067 mm) gauges to enter the works.
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 (165.1 mm). After one or two decades on increasing rancour, the dual gauge option was rejected as unacceptable, especially the Brennan dual gauge switch. Much later, ARTC accepted dual gauge turnouts for these gauges.
However, where the difference between the gauges is large, say 14.5 inches (368.3 mm) 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 or main line 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.
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.
- Melbourne to Geelong, Victoria, 80 km (50 mi), a single 1,435 mm (4 ft 8 1⁄2 in) standard gauge line parallel to double-track broad gauge.
- Yogyakarta–Solo in Java, Dutch East Indies during pre-WW II days, 58 km (36 mi). This had a single 3 ft 6 in (1,067 mm) line paralleling a dual-gauge 1,435 mm (4 ft 8 1⁄2 in) 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 3 ft 6 in (1,067 mm) narrow gauge and 1,435 mm (4 ft 8 1⁄2 in) 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 runs parallel to a double track 1,435 mm (4 ft 8 1⁄2 in) 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, 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.
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 1,524 mm (5 ft) gauge line runs from an iron ore mine in Ukraine to a steelworks in Slovakia, and now may be extended into Austria. Also, there is a portion of four-rail dual gauge 1435 vs. 1520 mm track from Slovakia to Romania (both standard gauge) via Ukraine (Russian gauge).
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.
- Rollbocks which do the same thing and have a similar height requirement.
- 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.
- Ramsey Car Transfer Apparatus, an alternative method of bogie exchange.
- 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
Model railways / miniature ridable railways
Tillig make dual gauge model railway track.
Many ridable miniature railways utilise dual gauge, often with models of the same prototype built to different scales to match the gauge.
- Central line to have standard gauge? Archived September 28, 2007, at the Wayback Machine.
- The length of Vietnam railway network Archived September 10, 2006, at the Wayback Machine.
- 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.
- "World infrastructure market March 2009". Railway Gazette International. 14 March 2009.
- Railway Digest August 2007
- "THE RAILWAY GAUGES.". The Mercury. Hobart, Tas.: National Library of Australia. 14 June 1872. p. 3. Retrieved 16 July 2012.
- "PERSONAL.". The Barrier Miner. Broken Hill, NSW: National Library of Australia. 3 July 1924. p. 2. Retrieved 1 September 2012.
- "GREAT WESTERN RAILWAY.". The Argus. Melbourne: National Library of Australia. 11 March 1926. p. 7. Retrieved 27 August 2011.
- "UNIFICATION OF GAUGES.". The Sydney Morning Herald. National Library of Australia. 6 May 1904. p. 5. Retrieved 10 March 2014.
- "SOUTH AUSTRALIA.". The Sydney Morning Herald. 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.
- "Broad gauge to Austria". Railway Gazette International. 2008-05-03. Retrieved 2008-05-15.
- "Dual gauge track – Model Railways – Forums – Railpage – Railpage Australia". Railpage. Retrieved 2012-09-24.
- 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