MAGNETIC LEVITATION TECHNOLOGY AND MODERN TRANSPORT SYSTEM 

Did you know that the fastest commercial train in the world uses a magnetic levitation (Maglev) technology rather than conventional steel wheels on steel rails, and that maglev transport systems are now operational in just three countries (Japan, South Korea and China)?

The Shanghai maglev train or Shanghai Transrapid is a magnetic levitation train (maglev) line that operates in Shanghai, China. It is the oldest commercial maglev still in operation, the first commercial high-speed maglev with cruising speed of 431 km/h (268 mph), and also the fastest commercial electric train in the world. China has also now developed its own 600 kph (373 mph) Maglev trains and has ambitious plans for a network of Maglevs, including a line between Shanghai and Hangzhou.

Maglev (magnetic levitation) is a system of train transportation that uses two sets of electromagnets: one set to repel and push the train up off the track, and another set to move the elevated train ahead, taking advantage of the lack of friction. Such trains rise approximately 10 centimetres (3.9 in) off the track. There are both high speed, intercity maglev systems (over 400 kilometres per hour (250 mph)), and low speed, urban maglev systems (80 kilometres per hour (50 mph) to 200 kilometres per hour (120 mph)) being built and under construction and development.

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 1970s. 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 mover was 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.

With maglev technology, the train travels along a guideway of electromagnets which control the train's stability and speed. While the propulsion and levitation require no moving parts, the bogies can move in relation to the main body of the vehicle and some technologies require support by retractable wheels at low speeds under 150 kilometres per hour (93 mph). This compares with electric multiple units that may have several dozen parts per bogie. Maglev trains can therefore in some cases be 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, although wind resistance at very high speeds can cause running costs that are four to five times that of conventional high-speed rail (such as the Tokaido Shinkansen). 

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 open-air land transport more energy intensive at higher speeds, takes the most energy. Vactrain technology 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 now operational in just three countries (Japan, South Korea and China). The incremental benefits of maglev technology have often been considered 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, such as high-speed rail in Europe.

Sources:

https://en.m.wikipedia.org/wiki/Maglev

https://en.m.wikipedia.org/wiki/Shanghai_maglev_train