SCMaglev test track in Yamanashi Prefecture, Japan
Transrapid 09 at the Emsland test facility in Germany
Maglev (derived from magnetic levitation) is a system of train transportation that uses two sets of magnets, one set to repel and push the train up off the track, then another set to move the 'floating train' ahead at great speed taking advantage of the lack of friction. Along certain "medium range" routes (usually 200–400 miles) Maglev can compete favorably with high-speed rail and airplanes.
With Maglev technology, there are no moving parts. The train travels along a guideway of magnets which control the train's stability and speed. Maglev trains are therefore quieter and smoother than conventional trains, and have the potential for much higher speeds.
Maglev vehicles have set several speed records and Maglev trains can accelerate and decelerate much faster than conventional trains; the only practical limitation is the safety and comfort of the passengers.
The power needed for levitation is typically not a large percentage of the overall energy consumption of a high speed maglev system. Overcoming drag, which makes all land transport more energy intensive at higher speeds, takes up the most energy. Vactraintechnology has been proposed as a means to overcome this limitation.
Maglev systems have been much more expensive to construct than conventional train systems, although the simpler construction of maglev vehicles makes them cheaper to manufacture and maintain.Despite over a century of research and development, maglev transport systems are in operation in just three countries (Japan, South Korea and China). The incremental benefits of maglev technology have often been hard to justify against cost and risk, especially where there is an existing or proposed conventional high speed train line with spare passenger carrying capacity, as in high-speed rail in Europe, the High Speed 2 in the UK and Shinkansen in Japan.
In the late 1940s, the British electrical engineer Eric Laithwaite, a professor at Imperial College London, developed the first full-size working model of the linear induction motor. He became professor of heavy electrical engineering at Imperial College in 1964, where he continued his successful development of the linear motor. Since linear motors do not require physical contact between the vehicle and guideway, they became a common fixture on advanced transportation systems in the 1960s and 70s. Laithwaite joined one such project, the Tracked Hovercraft, although the project was cancelled in 1973.
The linear motor was naturally suited to use with maglev systems as well. In the early 1970s, Laithwaite discovered a new arrangement of magnets, the magnetic river, that allowed a single linear motor to produce both lift and forward thrust, allowing a maglev system to be built with a single set of magnets. Working at the British Rail Research Division in Derby, along with teams at several civil engineering firms, the "transverse-flux" system was developed into a working system.
The first commercial maglev people moverwas simply called "MAGLEV" and officially opened in 1984 near Birmingham, England. It operated on an elevated 600 m (2,000 ft) section of monorail track between Birmingham Airport and Birmingham International railway station, running at speeds up to 42 km/h (26 mph). The system was closed in 1995 due to reliability problems.
First Maglev patentEdit
High-speed transportation patents were granted to various inventors throughout the world. Early United States patents for a linear motor propelled train were awarded to German inventor Alfred Zehden. The inventor was awarded U.S. Patent 782,312 (14 February 1905) and U.S. Patent RE12,700(21 August 1907). [note 1] In 1907, another early electromagnetic transportation system was developed by F. S. Smith. A series of German patents for magnetic levitation trains propelled by linear motors were awarded to Hermann Kemper between 1937 and 1941.[note 2] An early maglev train was described in U.S. Patent 3,158,765, "Magnetic system of transportation", by G. R. Polgreen (25 August 1959). The first use of "maglev" in a United States patent was in "Magnetic levitation guidance system" by Canadian Patents and Development Limited.
New York, United States, 1968Edit
In 1968, while delayed in traffic on the Throgs Neck Bridge, James Powell, a researcher at Brookhaven National Laboratory (BNL), thought of using magnetically levitated transportation.Powell and BNL colleague Gordon Danby worked out a MagLev concept using static magnets mounted on a moving vehicle to induce electrodynamic lifting and stabilizing forces in specially shaped loops, such as figure of 8 coils on a guideway.
Hamburg, Germany, 1979Edit
Transrapid 05 was the first maglev train with longstator propulsion licensed for passenger transportation. In 1979, a 908 m (2,979 ft) track was opened in Hamburg for the first International Transportation Exhibition (IVA 79). Interest was sufficient that operations were extended three months after the exhibition finished, having carried more than 50,000 passengers. It was reassembled in Kassel in 1980.
Ramenskoye, Moscow, USSR, 1979Edit
Experimental car TP-01 (ТП-01) in Ramenskoye built in 1979
Experimental car TP-05 (ТП-05) in Ramenskoye built in 1986
In 1979, in the USSR, in the town of Ramenskoye (Moscow oblast) was built an experimental test site for running experiments with cars on magnetic suspension. The test site consisted of a 600-meter ramp which was later extended to 980 meters. From the late 1970s to the 1980s five prototypes of cars were built that received designations from TP-01 (ТП-01) to TP-05 (ТП-05). The early cars were supposed to reach the speed up to 100 km/h.
The construction of a maglev track using the technology from Ramenskoye started in Armenian SSR in 1987 and was planned to be completed in 1991. The track was supposed to connect the cities of Yerevan and Sevan via the city of Abovyan. The original design speed was 250 km/h which was later lowered to 180 km/h. However, the Spitak earthquake in 1988 and the Nagorno-Karabakh war caused the project to freeze. In the end the overpass was only partially constructed.
In the early 1990s, the maglev theme was continued by the Engineering Research Center "TEMP" (ИНЦ "ТЭМП") this time by the order from the Moscow government. The project was named V250 (В250). The idea was to build a high-speed maglev train to connect Moscow to the Sheremetyevo airport. The train would consist of 64-seater cars and can run at the speeds up to 250 km/h. In 1993, due to the financial crisis, the project was abandoned. However, from 1999 the "TEMP" research center had been participating as a co-developer in the creation of the linear motors for the Moscow monorailsystem.
Birmingham, United Kingdom, 1984–95Edit
The Birmingham International Maglev shuttle
The world's first commercial maglev system was a low-speed maglev shuttle that ran between the airport terminal of Birmingham International Airport and the nearby Birmingham International railway stationbetween 1984 and 1995. Its track length was 600 m (2,000 ft), and trains levitated at an altitude of 15 mm (0.59 in), levitated by electromagnets, and propelled with linear induction motors. It operated for 11 years and was initially very popular with passengers, but obsolescence problems with the electronic systems made it progressively unreliable as years passed, leading to its closure in 1995. One of the original cars is now on display at Railworldin Peterborough, together with the RTV31hover train vehicle. Another is on display at the National Railway Museum in York.
Several favourable conditions existed when the link was built:
- The British Rail Research vehicle was 3 tonnes and extension to the 8 tonne vehicle was easy.
- Electrical power was available.
- The airport and rail buildings were suitable for terminal platforms.
- Only one crossing over a public road was required and no steep gradients were involved.
- Land was owned by the railway or airport.
- Local industries and councils were supportive.
- Some government finance was provided and because of sharing work, the cost per organization was low.
After the system closed in 1995, the original guideway lay dormant until 2003, when a replacement cable-hauled system, the AirRail Link Cable Liner people mover, was opened.
Emsland, Germany, 1984–2012Edit
Transrapid at the Emsland test facility
Transrapid, a German maglev company, had a test track in Emsland with a total length of 31.5 km (19.6 mi). The single-track line ran between Dörpen and Lathen with turning loops at each end. The trains regularly ran at up to 420 km/h (260 mph). Paying passengers were carried as part of the testing process. The construction of the test facility began in 1980 and finished in 1984. In 2006, the Lathen maglev train accident occurred killing 23 people, found to have been caused by human error in implementing safety checks. From 2006 no passengers were carried. At the end of 2011 the operation licence expired and was not renewed, and in early 2012 demolition permission was given for its facilities, including the track and factory.
JNR ML500 at a test track in Miyazaki, Japan, on 21 December 1979 travelled at 517 km/h (321 mph), authorized by Guinness World Records.
Japan operates two independently developed maglev trains. One is HSST (and its descendant, the Linimo line) by Japan Airlinesand the other, which is more well-known, is SCMaglev by the Central Japan Railway Company.
The development of the latter started in 1969. Miyazaki test track regularly hit 517 km/h (321 mph) by 1979. After an accident that destroyed the train, a new design was selected. In Okazaki, Japan (1987), the SCMaglev took a test ride at the Okazaki exhibition. Tests through the 1980s continued in Miyazaki before transferring to a far larger test track, 20 km (12 mi) long, in Yamanashi in 1997.
Development of HSST started in 1974. In Tsukuba, Japan (1985), the HSST-03 (Linimo) became popular in spite of its 30 km/h (19 mph) at the Tsukuba World Exposition. In Saitama, Japan (1988), the HSST-04-1 was revealed at the Saitama exhibition performed in Kumagaya. Its fastest recorded speed was 300 km/h (190 mph).
A new high speed maglev line, the Chuo Shinkansen, is planned to become operational in 2027, with construction starting 2017.
Vancouver, Canada and Hamburg, Germany, 1986–88Edit
HSST-03 at Okazaki Minami Park
In Vancouver, Canada, the HSST-03 by HSST Development Corporation (Japan Airlines and Sumitomo Corporation) was exhibited at Expo 86 and ran on a 400-metre (0.25 mi) test track that provided guests with a ride in a single car along a short section of track at the fairgrounds. It was removed after the fair and debut at the Aoi Expo in 1987 and now on static display at Okazaki Minami Park.
In Hamburg, Germany, the TR-07 was exhibited at the international traffic exhibition (IVA88) in 1988.
Berlin, Germany, 1989–91Edit
In West Berlin, the M-Bahn was built in the late 1980s. It was a driverless maglev system with a 1.6 km (0.99 mi) track connecting three stations. Testing with passenger traffic started in August 1989, and regular operation started in July 1991. Although the line largely followed a new elevated alignment, it terminated at Gleisdreieck U-Bahn station, where it took over an unused platform for a line that formerly ran to East Berlin. After the fall of the Berlin Wall, plans were set in motion to reconnect this line (today's U2). Deconstruction of the M-Bahn line began only two months after regular service began. It was called the Pundai project and was teminated in February 1992 due to safety concerns.
South Korea, 1993–presentEdit
South Korea's Incheon Airport Maglev, the world's fourth commercially operating maglev.
In 1993, South Korea completed the development of its own maglev train, shown off at the Taejŏn Expo '93, which was developed further into a full-fledged maglev capable of travelling up to 110 km/h (68 mph) in 2006. This final model was incorporated in the Incheon Airport Maglev which opened on February 3, 2016, making South Korea the world's fourth country to operate its own self-developed maglev after the United Kingdom's Birmingham International Airport,Germany's Berlin M-Bahn, and Japan's Linimo. It links Incheon International Airport to the Yongyu Station and Leisure Complex on Yeongjong island. It offers a transfer to the Seoul Metropolitan Subway at AREX's Incheon International Airport Stationand is offered free of charge to anyone to ride, operating between 9 am and 6 pm with 15 minute intervals.
The maglev system was co-developed by the South Korea Institute of Machinery and Materials (KIMM) and Hyundai Rotem. It is 6.1 kilometres (3.8 mi) long, with six stations and a 110 km/h (68 mph) operating speed.Two more stages are planned of 9.7 km (6.0 mi) and 37.4 km (23.2 mi). Once completed it will become a circular line.
In the public imagination, "maglev" often evokes the concept of an elevated monorailtrack with a linear motor. Maglev systems may be monorail or dual rail and not all monorail trains are maglevs. Some railway transport systems incorporate linear motors but use electromagnetism only for propulsion, without levitating the vehicle. Such trains have wheels and are not maglevs.Maglev tracks, monorail or not, can also be constructed at grade (i.e. not elevated). Conversely, non-maglev tracks, monorail or not, can be elevated too. Some maglev trains do incorporate wheels and function like linear motor-propelled wheeled vehicles at slower speeds but "take off" and levitate at higher speeds.[note 4]
MLX01 Maglev train Superconducting magnet bogie
The two notable types of maglev technology are:
- Electromagnetic suspension (EMS), electronically controlled electromagnets in the train attract it to a magnetically conductive (usually steel) track.
- Electrodynamic suspension (EDS) uses superconducting electromagnets or strong permanent magnets that create a magnetic field, which induces currents in nearby metallic conductors when there is relative movement, which pushes and pulls the train towards the designed levitation position on the guide way.
Another technology, which was designed, proven mathematically, peer-reviewed, and patented, but is, as of May 2015, unbuilt, is magnetodynamic suspension (MDS). It uses the attractive magnetic force of a permanent magnet array near a steel track to lift the train and hold it in place. Other technologies such as repulsive permanent magnets and superconducting magnets have seen some research.
Electromagnetic suspension (EMS)Edit
Electromagnetic suspension (EMS) is used to levitate the Transrapid on the track, so that the train can be faster than wheeled mass transit systems
In electromagnetic suspension (EMS) systems, the train levitates above a steel rail while electromagnets, attached to the train, are oriented toward the rail from below. The system is typically arranged on a series of C-shaped arms, with the upper portion of the arm attached to the vehicle, and the lower inside edge containing the magnets. The rail is situated inside the C, between the upper and lower edges.
Magnetic attraction varies inversely with the cube of distance, so minor changes in distance between the magnets and the rail produce greatly varying forces. These changes in force are dynamically unstable – a slight divergence from the optimum position tends to grow, requiring sophisticated feedback systems to maintain a constant distance from the track, (approximately 15 mm (0.59 in)).
The major advantage to suspended maglev systems is that they work at all speeds, unlike electrodynamic systems, which only work at a minimum speed of about 30 km/h (19 mph). This eliminates the need for a separate low-speed suspension system, and can simplify track layout. On the downside, the dynamic instability demands fine track tolerances, which can offset this advantage. Eric Laithwaite was concerned that to meet required tolerances, the gap between magnets and rail would have to be increased to the point where the magnets would be unreasonably large. In practice, this problem was addressed through improved feedback systems, which support the required tolerances.
Electrodynamic suspension (EDS)Edit
The Japanese SCMaglev's EDS suspension is powered by the magnetic fields induced either side of the vehicle by the passage of the vehicle's superconducting magnets.
EDS Maglev propulsion via propulsion coils
In electrodynamic suspension (EDS), both the guideway and the train exert a magnetic field, and the train is levitated by the repulsive and attractive force between these magnetic fields. In some configurations, the train can be levitated only by repulsive force. In the early stages of maglev development at the Miyazaki test track, a purely repulsive system was used instead of the later repulsive and attractive EDS system. The magnetic field is produced either by superconducting magnets (as in JR–Maglev) or by an array of permanent magnets (as in Inductrack). The repulsive and attractive force in the track is created by an induced magnetic field in wires or other conducting strips in the track. A major advantage of EDS maglev systems is that they are dynamically stable – changes in distance between the track and the magnets creates strong forces to return the system to its original position. In addition, the attractive force varies in the opposite manner, providing the same adjustment effects. No active feedback control is needed.
However, at slow speeds, the current induced in these coils and the resultant magnetic flux is not large enough to levitate the train. For this reason, the train must have wheels or some other form of landing gear to support the train until it reaches take-off speed. Since a train may stop at any location, due to equipment problems for instance, the entire track must be able to support both low- and high-speed operation.
Another downside is that the EDS system naturally creates a field in the track in front and to the rear of the lift magnets, which acts against the magnets and creates magnetic drag. This is generally only a concern at low speeds, and is one of the reasons why JR abandoned a purely repulsive system and adopted the sidewall levitation system. At higher speeds other modes of drag dominate.
The drag force can be used to the electrodynamic system's advantage, however, as it creates a varying force in the rails that can be used as a reactionary system to drive the train, without the need for a separate reaction plate, as in most linear motor systems. Laithwaite led development of such "traverse-flux" systems at his Imperial College laboratory. Alternatively, propulsion coils on the guideway are used to exert a force on the magnets in the train and make the train move forward. The propulsion coils that exert a force on the train are effectively a linear motor: an alternating current through the coils generates a continuously varying magnetic field that moves forward along the track. The frequency of the alternating current is synchronized to match the speed of the train. The offset between the field exerted by magnets on the train and the applied field creates a force moving the train forward.
The term "maglev" refers not only to the vehicles, but to the railway system as well, specifically designed for magnetic levitation and propulsion. All operational implementations of maglev technology make minimal use of wheeled train technology and are not compatible with conventional rail tracks. Because they cannot share existing infrastructure, maglev systems must be designed as standalone systems. The SPM maglev system is inter-operable with steel rail tracks and would permit maglev vehicles and conventional trains to operate on the same tracks. MAN in Germany also designed a maglev system that worked with conventional rails, but it was never fully developed.
Each implementation of the magnetic levitation principle for train-type travel involves advantages and disadvantages.