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Maglev

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Maglev can also mean general magnetic levitation.
Transrapid at the Emsland test facility
Maglev in Shanghai
Inside the Shanghai maglev

Magnetic levitation transport, or maglev, is a form of transportation that suspends, guides and propels vehicles via electromagnetic energy. This has advantages in terms of speed and ride comfort compared to wheeled mass transit systems - potentially, maglevs could reach velocities comparable to turboprop and jet aircraft (500 – 580 km/h) - but although the idea is decades old, technological and economic limitations have caused relatively few full-scale systems to be built. Maglev technology has minimal overlap with wheeled train technology and is not compatible with conventional railroad 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 vehicle/guideway interaction; each being a unique design element specifically tailored to the other to create and precisely control magnetic levitation.

The various technological approaches to maglev can be very similar or very different, depending upon the manufacturer.

Due to the lack of physical contact between the track and the vehicle, the only friction exerted is that between the vehicles and the air. Consequently maglevs can potentially travel at very high speeds with reasonable energy consumption and noise levels. Systems have been proposed that operate at up to 650 km/h (404 mph), which is far faster than is practical with conventional rail transport. The very high maximum speed potential of maglevs make them competitors to airline routes of 1,000 kilometers (600 miles) or less. The world's first commercial application of a high-speed maglev line is the IOS (initial operating segment) demonstration line in Shanghai that transports people 30 km (18.6 miles) to the airport in just 7 minutes 20 seconds (top speed of 431 km/h or 268 mph, average speed 250 km/h or 150 mph). Other maglev applications worldwide are being investigated for feasibility.

The futurist American writer, Allan Silliphant, has proposed a fundamental model of urban metro transit that addresses the problem of going from a central point such as a city center, or an airport, to various points on the periphery of a circle around that center. Using Los Angeles, as an example, it can take 2.5 hours to cross the city by auto. This is true of most very large world cities. A deeply constructed maglev radial system, below any existing structures or utilites, can be bored out in virgin bedrock or undisturbed sediment. With a depth of 200 to 300 feet it would be possible to go almost anywhere in most metro areas. A transfer point in the middle will reduce the number of trains needed. Non-stop, cross-metro tubes could also be constructed, next to the tube terminating in the center hub, avoiding a transfer. Present maglev speeds of even 200 miles/hour will greatly facilitate movement within an urban center. Surface maglev trains, can continue the outbound movement to the next urban center where a similar "hub and spoke" maglev deep tube system can be established. This can save many billions in fossil fuel consumption, especially if very quick access can be provided at the stations to rental cars and timely connection to public transport on the surface.

Technology

File:Maglev Propulsion.gif
Maglev Propulsion
See also: Fundamental Technology Elements in the JR-Maglev article.
See also: Technology in the Transrapid article.

Three types of technology

There are three primary types of maglev technology:

Japan and Germany are active in maglev research, producing several different approaches and designs. In one design, the train can be levitated by the repulsive force of like poles or the attractive force of opposite poles of magnets. The train can be propelled by a linear motor on the track or on the train, or both. Massive electrical induction coils are placed along the track in order to produce the magnetic field necessary to propel the train.

Unmoving magnetic bearings using purely electromagnets or permanent magnets are unstable because of Earnshaw's theorem; on the other hand diamagnetic and superconducting magnets can support a maglev stably. Conventional maglev systems are stabilized with electromagnets that have electronic stabilization.

The weight of the large electromagnet is a major design issue. A very strong magnetic field is required to levitate a massive train, so conventional maglev research is using superconductor research for an efficient electromagnet.

Inductrack

A newer, perhaps less-expensive, system is called "Inductrack". The technique has a load-carrying ability related to the speed of the vehicle, because it depends on currents induced in a passive electromagnetic array by permanent magnets. In the prototype, the permanent magnets are in a cart; horizontally to provide lift, and vertically to provide stability. The array of wire loops is in the track. The magnets and cart are unpowered, except by the speed of the cart. Inductrack was originally developed as a magnetic motor and bearing for a flywheel to store power. With only slight design changes, the bearings were unrolled into a linear track. Inductrack was developed by physicist Richard Post at Lawrence Livermore National Laboratory.

Inductrack uses Halbach arrays for stabilization. Halbach arrays are arrangements of permanent magnets that stabilize moving loops of wire without electronic stabilization. Halbach arrays were originally developed for beam guidance of particle accelerators. They also have a magnetic field on the track side only, thus reducing any potential effects on the passengers.

Spacecraft research

Currently, some space agencies, such as NASA, are researching the use of maglev systems to launch spacecraft. In order to do so, the space agency would have to get a maglev-launched spacecraft up to escape velocity, a task that would otherwise require elaborate timing of magnetic pulses (see coilgun) or a very fast, very powerful electric current (see railgun). Maglev-launching could also be used to make conventional launches more efficient: accelerating a craft up to mach 1 before firing the main engines can save 30% of the weight of the launch vehicle (Heller, 1998).

Pros and Cons of different technologies

Each implementation of the magnetic levitation principle for train-type travel involves advantages and disadvantages. Time will tell as to which principle, and whose implementation, wins out commercially.

Technology    Pros    Cons
EMS (Electromagnetic) Does not carry its propulsion system; can attain very high speeds; magnetic fields inside and outside the vehicle are insignificant; highly reliable computer controlled operations; proven, commercially available technology Guideway includes stator packs along entire length which add cost to construction, but do enable high speeds without vehicle weight penalty.
Superconducting EDS (Electrodynamic) Powerful onboard superconducting magnets enable high speeds and heavy load capacity; has recently demonstrated (Dec 2005) successful operations using high temperature superconductors (HTS) in its onboard magnets, cooled with inexpensive liquid nitrogen Up until 2005, the system used low-temperature superconductors refrigerated with liquid helium - an extremely expensive approach; strong magnetic fields onboard the train make the train inaccessible to passengers with pacemakers; vehicle must be wheeled for travel at low speeds; system per mile cost still considered prohibitive.
Inductrack System (Permanent Magnets) Failsafe suspension - no power required to activate magnets New technology still under development (2005); also needs wheels

It must be noted, that the Inductrack and the Superconducting EDS are only levitation technologies. In both cases, vehicles need some other technology for propulsion. A linear motor is used for propulsion in Japanese Superconducting EDS MLX01 maglev. Inductrack, should it ever be developed into a commercial transport technology, will have to solve the propulsion problem, as well as the need to deliver the propulsion energy onboard (due to itself being a completely passive technology). A Jet engine or a linear motor are being considered.

The German Transrapid electromagnetic maglev uses a linear motor for both levitation and propulsion.

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 both systems, whereas EMS systems are wheel-less.

The German Transrapid, Japanese HSST (Linimo), and Korean Rotem 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.

Existing Maglev Systems

JR-Maglev at Yamanashi

Birmingham 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 (UK) to the nearby Birmingham International railway station from 1984 to 1995. The length of the track was 600 m, and trains "flew" at an altitude of 15 mm. It was in operation for nearly eleven years, but obsolescence problems with the electronic systems made it unreliable in its later years and it has now been replaced with a cable-drawn system.

Berlin 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.

Emsland

Transrapid, a German maglev company, has a test track in Emsland with a total length of 31.5 km.

Shanghai Maglev Train

Main article: Shanghai Maglev Train

Transrapid constructed the first operational high-speed conventional maglev railway in the world, the Shanghai Maglev Train from downtown Shanghai, China to the new Shanghai airport at Pudong. 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. Transrapid uses EMS technology.

JR-Maglev

Japan has a test track in Yamanashi prefecture where test trains JR-Maglev MLX01 have reached 581 km/h (363 mph), faster than wheeled trains. 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 Co. ("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.

Linimo, Nagoya East Hill Line

The world's first commercial automated "Urban Maglev" system commenced operation in March 2005 in Japan.[citation needed] This is the nine-station 8.9 km-long Tobu-kyuryo Line Linimo, otherwise known as the Nagoya East Hill Line. 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 of 2007.

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.

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 and the levitation gap over 20 mm. The system uses liquid nitrogen, which is very cheap, to cool the superconductor.

US patent, 1969

The first patent for a magnetic levitation train propelled by linear motors was US patent 3,470,828, issued in October 1969 to James R. Powell and Gordon T. Danby. The technology underlying it was invented by Eric Laithwaite, and described by him in "Proceedings of the Institution of Electrical Engineers", vol. 112, 1965, pp. 2361-2375, under the title "Electromagnetic Levitation". Laithwaite patented the linear motor in 1948.

Economics

High-speed maglevs can be expensive to build, but are comparable to the capital costs of building a traditional high-speed rail system from scratch, a highway system or a system of airports. More importantly, maglevs are significantly less expensive to operate and maintain (O&M) than traditional high-speed trains, planes or intercity buses. The data coming out of the Shanghai maglev demonstration project indicates that O&M costs are quite low, and are indeed covered by the current relatively low volume of 7,000 passengers per day. Ridership on this Pudong International Airport line is expected to rise dramatically once the line is extended from Longyang Road metro station all the way to Shanghai's downtown train depot.

The Shanghai maglev cost US$1.2B to build which means that at 20,000 passengers a day at US$6 per passenger it will take around 30 years to pay off just the capital costs, not accounting for track maintenance, salaries and electricity. This computes to US$60 million per mile. The proposed Chuo Shinkansen line is estimated to cost approximately US$82 billion to build.

However, when one considers the cost of airport construction (e.g. Hong Kong Airport cost US$20 billion to build in 1998) and 8-lane Interstate highway systems that cost around US$50 million per mile, it becomes immediately apparent that maglev's costs are competitive, especially considering that they can handle much higher volumes of passengers per hour than airports or 8-lane highways and do it without introducing any air pollution along their ROW's (right of way).

Low-speed maglevs (100 km/h, or 60 mph), such as the Japanese HSST or Korean Rotem, are expected to cost somewhere around US$30 million per mile. Besides offering improved O&M costs over other transit systems, these low-speed maglevs provide ultra-high levels of operational reliability and introduce zero noise or air pollution into dense urban settings.

As maglev systems are deployed around the world, experts fully expect construction costs to drop as new construction methods are perfected.

Under Construction

Old Dominion University

A track of less than a mile in length has been constructed at Old Dominion University in Norfolk, Virginia. The system is not operational, but research is currently ongoing to resolve some stability issues with the system. This system uses a "smart train, dumb track" that involves most of the sensors, magnets, and computation occuring on the train rather than the track. This system will cost less to build per mile than existing systems.

Proposals

Tokyo-Osaka

If a proposed Chuo Shinkansen is built, connecting Tokyo to Osaka by maglev, the existing test track in Yamanashi prefecture would be part of the line.

Munich

A Transrapid connection of the Bavarian capital Munich to its international airport (37 km) is now being planned. It would reduce the current connection time via S-Bahn (German city railroad system) from about 40 minutes to 10 minutes.

Shanghai-Hangzhou

China is considering maglev as a possible technology option for building a planned high-speed rail network to connect major cities, although the cost may make this impractical. Talks with Germany on the possible construction of a second Transrapid maglev rail linking Shanghai to Hangzhou have started. The Shanghai-Hangzhou maglev line would have to be in service no later than 2010, becoming the first inter-city Maglev rail line in commercial service in the world. The line will be an extension of the Shanghai airport Maglev line and the first part of a maglev line linking Shanghai and Beijing.

London- Edinburgh and/or Glasgow

A maglev line has recently been proposed in the United Kingdom from London to Edinburgh and/or Glasgow with several route options through the Midlands and Northeast, and is reported to be under favourable consideration by the government. A further high speed link is also being investigated as an option between Glasgow to Edinburgh though there is no settled technology for this concept yet, ie (Maglev/Hi Speed Electric etc) [1] [2]

Honolulu

The city of Honolulu, Hawaii is said to be planning a Linimo class urban Maglev for its main mass transit train.

San Diego

San Diego is considering a high-speed maglev line to serve as a passenger transportation node to remote airport sites under consideration. The cost estimate is approximately $10 billion US for the 80-100 mile run, not including the cost of construction of the airport. [3]

Southern California, Las Vegas

High-speed maglev lines between major cities of southern California and Las Vegas are also being studied. This plan was originally supposed to be part of a I-5 or I-15 expansion plan, but the federal government has ruled it must be separated from interstate work projects.

Baltimore-Washington

A 64 km project linking Camden Yards in Baltimore and Baltimore-Washington International (BWI) Airport to Union Station in Washington, D.C.

Pittsburgh

A 75 km project linking Pittsburgh International Airport to Pittsburgh and its eastern suburbs.

Berlin-Hamburg

A 292 km Transrapid line linking Berlin to Hamburg. It has been deleted due to lack of funds.

Vactrain

see also Swissmetro

More exotic proposals include maglev lines through vacuum-filled tunnels (see Vactrain), where the absence of air resistance would allow extremely high speeds, up to 6000-8000 km/h (4000-5000 mph) according to some sources. Theoretically, these tunnels could be built deep enough to pass under oceans or to use gravity to assist the trains' acceleration. This would likely be prohibitively costly without major advances in tunnelling technology. Alternatives such as elevated concrete tubes with partial vacuums have been proposed to reduce these costs. If the trains topped out at around 8000 km/h (5000 mph), the trip between London and New York would take a breathtakingly short 54 minutes, effectively supplanting aircraft as the world's fastest mode of public transportation.

UniModal

UniModal is a proposed personal rapid transit system using Inductrack suspension to achieve average commute speeds of 160 km/h (100 mph) in the city.

References

  • Heller, Arnie (June 1998). "A New Approach for Magnetically Levitating Trains--and Rockets". {{cite news}}: Unknown parameter |org= ignored (help)
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See also

Transrapid

Japanese Maglev

Linear Motor Car

Linimo

Maglev train companies

These websites contain further information provided by companies building maglev trains (alphabetical order).

General

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