A maglev, or magnetically levitating train is a form of transportation that suspends, guides and propels vehicles (predominantly trains) using electromagnetic force. This method has the potential to be faster and quieter than wheeled mass transit systems, potentially reaching velocities comparable to turboprop and jet aircraft (900 km/h, 600 mph).
The highest recorded speed of a maglev train is 581 km/h (361 mph), achieved in Japan in 2003, 6 km/h faster than the conventional TGV speed record.
[edit] History
In the 1960s, Great Britain held the lead in maglev research;[1] Eric Laithwaite, Professor of Heavy Electrical Engineering at Imperial College, developed a functional maglev passenger vehicle. It weighed 1 ton (1 tonne) and could carry four passengers.[1] Additional funding for his work was also provided by British Rail, the British Transport Commission, Manchester University, Surrey University and the Wolfson Foundation.[1] His maglev had one mile (1.6 km) of track and was thoroughly tested, but his research was cut off in 1973 due to lack of funding; and his progress was not sufficient. British Rail also set up a Maglev Experimental Centre at their Railway Technical Centre based at Derby.
In the 1970s, Germany and Japan also began research and after some failures both nations developed mature technologies in the 1990s.
[edit] First patents
High speed transportation patents would be granted to various inventors throughout the world.[2] Early United States patents for a linear motor propelled train were awarded to the inventor, Alfred Zehden (German). The inventor would gain U.S. Patent 782,312 (June 21, 1902) and U.S. Patent RE12,700 (August 21, 1907).[3] In 1907, another early electromagnetic transportation system was developed by F. S. Smith.[4] A series of German patents for magnetic levitation trains propelled by linear motors were awarded to Hermann Kemper between 1937 and 1941.[5] An early modern type of maglev train was described in U.S. Patent 3,158,765, Magnetic system of transportation, by G. R. Polgreen (August 25, 1959). The first use of "maglev" in a United States patent was in "Magnetic levitation guidance"[6] by Canadian Patents and Development Limited.
[edit] Upton, NY, 1968
In 1961, when he was delayed during rush hour traffic on the Throgs Neck Bridge, James Powell, a researcher at Brookhaven National Laboratory (BNL), thought of using magnetically levitated transportation to solve the traffic problem. Powell and BNL colleague Gordon Danby jointly worked out a MagLev concept using static magnets mounted on a moving vehicle to induce electrodynamic lifting and stabilizing forces in specially shaped loops on a guideway. The two researchers obtained a patent on the technology in 1968.[7]
[edit] Hamburg, Germany 1979
There is conflict in this information. Transrapid 05 was the first maglev train with longstator propulsion licensed for passenger transportation. In 1979 a 908 m track was open in Hamburg for the first International Transportation Exhibition (IVA 79). There was so much interest that operation had to be extended three months after exhibition finished, after carrying more than 50,000 passengers. It was reassembled in Kassel in 1980.
[edit] Birmingham, England 1984–1995
The world's first commercial automated system was a low-speed maglev shuttle that ran from the airport terminal of Birmingham International Airport to the nearby Birmingham International railway station from 1984 to 1995. Based on experimental work commissioned by the British government at the British Rail Research Division laboratory at Derby, the length of the track was 600 meters (1,969 ft), and trains "flew" at an altitude of 15 millimeters (0.6 in). It was in operation for nearly eleven years, but obsolescence problems with the electronic systems (lack of spare parts) made it unreliable in its later years and it has now been replaced with a cable-drawn system. One of the original cars now sits in part of the airport.
Several favourable conditions existed when the link was built:
- The British Rail Research vehicle was 3 tons (3 tonne) and extension to the 8 ton (8 tonne) vehicle was easy.
- Electrical power was easily 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 not high.
[edit] Japan, 1980s
Maglev speeds on the Miyazaki test track had regularly hit 517 km/h by 1979, but after an accident that destroyed the train, a new design was decided upon. Tests through the 1980s continued in Miyazaki before transferring a far larger and elaborate test track (20 km long) in Yamanashi in the late 1990s.
In Tsukuba, Japan (1985), the HSST-03 (Linimo) wins popularity in spite of being 30 km/h slower Tsukuba World Exposition. In Okazaki, Japan (1987), the JR-Maglev took a test ride at the Okazaki exhibition. In Saitama, Japan (1988), the HSST-04-1 was revealed at the Saitama exhibition performed in Kumagaya. Its fastest recorded speed was 30 km/h. In Yokohama, Japan (1989), the HSST-05 acquires a business driver's license at Yokohama exhibition and carries out general test ride driving. Maximum speed 42 km/h.
[edit] Vancouver, Canada & Hamburg, Germany 1986-1988
In Vancouver, Canada (1986), the JR-Maglev took a test ride at holding Vancouver traffic exhibition and runs. In Hamburg, Germany (1988), the TR-07 in international traffic exhibition (IVA88) performed Hamburg.
[edit] Berlin, Germany 1989–1991
In West Berlin, the M-Bahn was built in the late 1980s. It was a driverless maglev system with a 1.6 km track connecting three stations. Testing in 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 the U-Bahn station Gleisdreieck, where it took over a platform that was then no longer in use; it was from 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 and was completed in February 1992.
[edit] Commercial operation
The first commercial Maglev "people-mover" was officially opened in 1984 in Birmingham, England. It operated on an elevated 600-metre (1,969 ft) section of monorail track between Birmingham International Airport and Birmingham International railway station. It ran at 42 km/h (26 mph) until the system was eventually closed in 1995 due to reliability and design problems.
The best-known high-speed maglev currently operating commercially is the IOS (initial operating segment) demonstration line of the German built Transrapid train in Shanghai, China that transports people 30 km (18.6 miles) to the airport in just 7 minutes 20 seconds, achieving a top velocity of 431 km/h (268 mph), averaging 250 km/h (150 mph).
Other commercially operating lines exist in Japan, such as the Linimo line. Maglev projects worldwide are being studied for feasibility. In Japan at the Yamanashi test track, current maglev train technology is mature, but costs and problems remain a barrier to development, alternative technologies are being developed to address those issues.
[edit] Technology
All operational implementations of maglev technology have had minimal overlap with wheeled train technology and have not been compatible with conventional rail tracks. Because they cannot share existing infrastructure, maglevs must be designed as complete transportation systems. The term "maglev" refers not only to the vehicles, but to the railway system as well, specifically designed for magnetic levitation and propulsion.
- See also fundamental technology elements in the JR-Maglev article, Technology in the Transrapid article, Magnetic levitation
There are two primary types of maglev technology:
- electromagnetic suspension (EMS) uses the attractive magnetic force of a magnet beneath a rail to lift the train up.
- electrodynamic suspension (EDS) uses a repulsive force between two magnetic fields to push the train away from the rail.
Another experimental technology, which was designed, proven mathematically, peer reviewed, and patented, but is yet to be built, is the magnetodynamic suspension (MDS), which uses the attractive magnetic force of a permanent magnet array near a steel track to lift the train and hold it in place.
[edit] Electromagnetic suspension
In current EMS systems, the train levitates above a steel rail while electromagnets, attached to the train, are oriented toward the rail from below. The electromagnets use feedback control to maintain a train at a constant distance from the track, at approximately 15 millimeters (0.6 in).[8][9]
[edit] Electrodynamic suspension
In Electrodynamic suspension (EDS), both the rail and the train exert a magnetic field, and the train is levitated by the repulsive force between these magnetic fields. The magnetic field in the train is produced by either electromagnets (as in JR-Maglev) or by an array of permanent magnets (as in Inductrack). The repulsive force in the track is created by an induced magnetic field in wires or other conducting strips in the track.
At slow speeds, the current induced in these coils and the resultant magnetic flux is not large enough to support the weight of the train. For this reason the train must have wheels or some other form of landing gear to support the train until it reaches a speed that can sustain levitation.
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 flowing 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 create a force moving the train forward.
[edit] Pros and cons of different technologies
Each implementation of the magnetic levitation principle for train-type travel involves advantages and disadvantages. Time will tell us which principle, and whose implementation, wins out commercially.
| | ||||
| Technology | Pros | Cons | ||
| | ||||
| EMS (Electromagnetic) | Magnetic fields inside and outside the vehicle are insignificant; proven, commercially available technology that can attain very high speeds (500 km/h); no wheels or secondary propulsion system needed | The separation between the vehicle and the guideway must be constantly monitored and corrected by computer systems to avoid collision due to the unstable nature of electromagnetic attraction; due to the system's inherent instability and the required constant corrections by outside systems, vibration issues may occur. | ||
| | ||||
| EDS (Electrodynamic) | Onboard magnets and large margin between rail and train enable highest recorded train speeds (581 km/h) and heavy load capacity; has recently demonstrated (December 2005) successful operations using high temperature superconductors in its onboard magnets, cooled with inexpensive liquid nitrogen | Strong magnetic fields onboard the train would make the train inaccessible to passengers with pacemakers or magnetic data storage media such as hard drives and credit cards, necessitating the use of magnetic shielding; limitations on guideway inductivity limit the maximum speed of the vehicle; vehicle must be wheeled for travel at low speeds; used in JR-Maglev. | ||
| | ||||
| Inductrack System (Permanent Magnet EDS) | Failsafe Suspension - no power required to activate magnets; Magnetic field is localized below the car; can generate enough force at low speeds (around 5 km/h) to levitate maglev train; in case of power failure cars slow down on their own safely; Halbach arrays of permanent magnets may prove more cost-effective than electromagnets | Requires either wheels or track segments that move for when the vehicle is stopped. New technology that is still under development (as of 2008) and as yet has no commercial version or full scale system prototype. | ||
Neither Inductrack nor the Superconducting EDS are able to levitate vehicles at a standstill, although Inductrack provides levitation down to a much lower speed. Wheels are required for these systems. EMS systems are wheel-less.
The German Transrapid, Japanese HSST (Linimo), and Korean Rotem EMS maglevs levitate at a standstill, with electricity extracted from guideway using power rails for the latter two, and wirelessly for Transrapid. If guideway power is lost on the move, the Transrapid is still able to generate levitation down to 10 km/h speed, using the power from onboard batteries. This is not the case with the HSST and Rotem systems.
[edit] Propulsion
An EMS system can provide both levitation and propulsion using an onboard linear motor. EDS systems can only levitate the train using the magnets onboard, not propel it forward. As such, vehicles need some other technology for propulsion. A linear motor (propulsion coils) mounted in the track is one solution. Over long distances where the cost of propulsion coils could be prohibitive, a propeller or jet engine could be used.
[edit] Stability
Earnshaw's theorem shows that any combination of static magnets cannot be in a stable equilibrium. However, the various levitation systems achieve stable levitation by violating the assumptions of Earnshaw's theorem. Earnshaw's theorem assumes that the magnets are static and unchanging in field strength and that permeability is constant everywhere. EMS systems rely on active electronic stabilization. Such systems constantly measure the bearing distance and adjust the electromagnet current accordingly. All EDS systems are moving systems (no EDS system can levitate the train unless it is in motion).
Because Maglev vehicles essentially fly, stabilisation of pitch, roll and yaw is required by magnetic technology. In addition translations, surge (forward and backward motions), sway (sideways motion) or heave (up and down motions) can be problematic with some technologies.
[edit] Pros and cons of maglev
[edit] Maglev vs. conventional trains
Maglev trains are not compatible with conventional track, and therefore require all new infrastructure for their entire route. By contrast conventional high speed trains such as the TGV are able to run at reduced speeds on existing rail infrastructure, thus reducing expenditure where new infrastructure would be particularly expensive (such as the final approaches to city terminals), or on extensions where traffic does not justify new infrastructure.
Due to the lack of physical contact between the track and the vehicle, Maglev trains experience no rolling friction, leaving only air resistance and electromagnetic drag, potentially improving power efficiency.[10]
The weight of the large electromagnets in EMS and EDS designs is a major design issue. A very strong magnetic field is required to levitate a massive train. For this reason one research path is using superconductors to improve the efficiency of the electromagnets.
The high speed of some maglev trains translates to more sound due to air displacement, which gets louder as the trains go faster. A study found that high speed maglev trains are 5 dB noisier than traditional trains.[11][12] At low speeds, however, maglev trains are nearly silent. However, two trains passing at a combined 1,000 km/h has been successfully demonstrated without major problems in Japan.
Braking issues and overhead wire wear are problems for the Fastech 360 railed Shinkansen. Maglev would eliminate these issues, but not the noise pollution issue.
Issues relating to magnets are also a factor. See suspension types.
As linear motors must fit within or straddle their track over the full length of the train, track design is challenging for anything other than point-to-point services. Curves must be gentle and avoid camber, while switches are very long and need care to avoid breaks in current.
Maglev needs very fast-responding control systems to maintain a stable height above the track; this needs careful design in the event of a failure in order to avoid crashing into the track during a power fluctuation.
[edit] Maglev vs aircraft
One advantage of maglev's higher speed would be extension of the serviceable area (3 hours radius) that can outcompete subsonic commercial aircraft.
For many systems, it is possible to define a lift-to-drag ratio. These ratios can exceed that of aircraft (for example Inductrack can approach 200:1 at high speed, far higher than any aircraft). This can make it more efficient per mile, and potentially give greater range.
Aircraft travel at high altitude where the airdrag is lower, and hence can travel faster, and can service more destinations.
[edit] Economics
The Shanghai maglev cost 9.93 billion yuan (US$1.2 billion) to build.[13] This total includes infrastructure capital costs such as manufacturing and construction facilities, and operational training. At 50 yuan per passenger[14] and the current 7,000 passengers per day, income from the system is incapable of recouping the capital costs (including interest on financing) over the expected lifetime of the system, even ignoring operating costs[citation needed].
China aims to limit the cost of future construction extending the maglev line to approximately 200 million yuan (US$24.6 million) per kilometer.[13] These costs compare competitively with airport construction (e.g., Hong Kong Airport cost US$20 billion to build in 1998) and eight-lane Interstate highway systems that cost around US$50 million per mile (US$31 million per kilometer) in the US.
While high-speed maglevs are expensive to build, they are less expensive to operate and maintain than traditional high-speed trains, planes or intercity buses.[citation needed] Data from the Shanghai maglev project indicates that operation and maintenance costs are covered by the current relatively low volume of 7,000 passengers per day.[citation needed] Passenger volumes on the Pudong International Airport line are expected to rise dramatically once the line is extended from Longyang Road metro station all the way to Shanghai's downtown train depot.
The proposed Chūō Shinkansen maglev in Japan is estimated to cost approximately US$82 billion to build, with a route blasting long tunnels through mountains. A Tokaido maglev route replacing current Shinkansen would cost some 1/10th the cost, as no new tunnel blasting would be needed, but noise pollution issues would make it infeasible.
The only low-speed maglev (100 km/h) currently operational, the Japanese Linimo HSST, cost approximately US$100 million/km to build.[15] Besides offering improved operation and maintenance costs over other transit systems, these low-speed maglevs provide ultra-high levels of operational reliability and introduce little noise and zero air pollution into dense urban settings.
As maglev systems are deployed around the world, experts expect construction costs to drop as new construction methods are perfected.[citation needed]
[edit] History of maximum speed record by a trial run
- 1971 - West Germany - Prinzipfahrzeug - 90 km/h
- 1971 - West Germany -TR-02(TSST)- 164 km/h
- 1972 - Japan - ML100 - 60 km/h - (manned)
- 1973 - West Germany - TR04 - 250 km/h (manned)
- 1974 - West Germany - EET-01 - 230 km/h (unmanned)
- 1975 - West Germany - Komet - 401.3 km/h (by steam rocket propulsion, unmanned)
- 1978 - Japan - HSST-01 - 307.8 km/h (by supporting rockets propulsion, made in Nissan, unmanned)
- 1978 - Japan - HSST-02 - 110 km/h (manned)
- 1979-12-12 - Japan-ML-500R - 504 km/h (unmanned) It succeeds in operation over 500 km/h for the first time in the world.
- 1979-12-21 - Japan -ML-500R- 517 km/h (unmanned)
- 1987 - West Germany - TR06 - 406 km/h (manned)
- 1987 - Japan - MLU001 - 400.8 km/h (manned)
- 1988 - West Germany - TR-06 - 412.6 km/h (manned)
- 1989 - West Germany - TR-07 - 436 km/h (manned)
- 1993 - Germany - TR-07 - 450 km/h (manned)
- 1994 - Japan - MLU002N - 431 km/h (unmanned)
- 1997 - Japan - MLX01 - 531 km/h (manned)
- 1997 - Japan - MLX01 - 550 km/h (unmanned)
- 1999 - Japan - MLX01 - 548 km/h (unmanned)
- 1999 - Japan - MLX01 - 552 km/h (manned/five formation).
Guinness authorization.
- 2003 - China - TR-08 - 501 km/h (manned)
- 2003 - Japan - MLX01 - 581 km/h (manned/three formation).
[edit] Existing maglev systems
[edit] Emsland, Germany
Transrapid, a German maglev company, has a test track in Emsland with a total length of 31.5 km (19.6 mi). The single track line runs between Dörpen and Lathen with turning loops at each end. The trains regularly run at up to 420 km/h (261 mph). The construction of the test facility began in 1980 and finished in 1984.
[edit] JR-Maglev, Japan
Japan has a demonstration line in Yamanashi prefecture where test trains JR-Maglev MLX01 have reached 581 km/h (361 mph), slightly faster than any wheeled trains (the current TGV speed record is 574.8 km/h, 357.0 mph).
These trains use superconducting magnets which allow for a larger gap, and repulsive-type Electro-Dynamic Suspension (EDS). In comparison Transrapid uses conventional electromagnets and attractive-type Electro-Magnetic Suspension (EMS). These "Superconducting Maglev Shinkansen", developed by the Central Japan Railway Company (JR Central) and Kawasaki Heavy Industries, are currently the fastest trains in the world, achieving a record speed of 581 km/h on December 2, 2003. Yamanashi Prefecture residents (and government officials) can sign up to ride this for free, and some 100,000 have done so already.
[edit] Linimo (Tobu Kyuryo Line, Japan)
The world's first commercial automated "Urban Maglev" system commenced operation in March 2005 in Aichi, Japan. This is the nine-station 8.9 km long Tobu-kyuryo Line, otherwise known as the Linimo. The line has a minimum operating radius of 75 m and a maximum gradient of 6%. The linear-motor magnetic-levitated train has a top speed of 100 km/h. The line serves the local community as well as the Expo 2005 fair site. The trains were designed by the Chubu HSST Development Corporation, which also operates a test track in Nagoya. Urban-type maglevs patterned after the HSST have been constructed and demonstrated in Korea, and a Korean commercial version Rotem is now under construction in Daejeon and projected to go into operation by April 2007.
[edit] FTA's UMTD program
In the US, the Federal Transit Administration (FTA) Urban Maglev Technology Demonstration program has funded the design of several low-speed urban maglev demonstration projects. It has assessed HSST for the Maryland Department of Transportation and maglev technology for the Colorado Department of Transportation. The FTA has also funded work by General Atomics at California University of Pennsylvania to demonstrate new maglev designs, the MagneMotion M3 and of the Maglev2000 of Florida superconducting EDS system. Other US urban maglev demonstration projects of note are the LEVX in Washington State and the Massachusetts-based Magplane.
[edit] Southwest Jiaotong University, China
On December 31, 2000, the first crewed high-temperature superconducting maglev was tested successfully at Southwest Jiaotong University, Chengdu, China. This system is based on the principle that bulk high-temperature superconductors can be levitated or suspended stably above or below a permanent magnet. The load was over 530 kg (1166 lb) and the levitation gap over 20 mm (0.79 in). The system uses liquid nitrogen, which is very cheap, to cool the superconductor.
[edit] Shanghai Maglev Train
Transrapid, in Germany, constructed the first operational high-speed conventional maglev railway in the world, the Shanghai Maglev Train from downtown Shanghai (Shanghai Metro) to the Pudong International Airport. It was inaugurated in 2002. The highest speed achieved on the Shanghai track has been 501 km/h (311 mph), over a track length of 30 km. The plan for the Shanghai-Hangzhou Maglev Train was approved by the central government in February 2006, with plans for completion by 2010.
[edit] Under construction
[edit] Old Dominion University
A track of less than a mile in length has been constructed at Old Dominion University in Norfolk, Virginia, USA. Although the system was initially built by AMT, problems caused the company to abandon the project and turn it over to the University.[16][17] The system is currently not operational, but research is ongoing to resolve stability issues with the system. This system uses a "smart train, dumb track" that involves most of the sensors, magnets, and computation occurring on the train rather than the track. This system will cost less to build per mile than existing systems. The $14 million originally planned did not allow for completion.
[edit] AMT Test Track - Powder Springs, Georgia
The same principle is involved in the construction of a second prototype system in Powder Springs, Georgia, USA, by American Maglev Technology, Inc.
[edit] Proposed systems
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