Maglev (derived from magnetic levitation), is a system of transportation that uses magnetic levitation to suspend, guide and propel vehicles from magnets rather than using mechanical methods, such as wheels, axles and bearings. Maglev transport is a means of flying a vehicle or object along a guideway by using magnets to create both lift and thrust, only a few inches above the guideway surface. High-speed maglev vehicles are lifted off their guideway and thus are claimed to move more smoothly and quietly and require less maintenance than wheeled mass transit systems – regardless of speed. It is claimed that non-reliance on friction also means that acceleration and deceleration can far surpass that of existing forms of transport. The power needed for levitation is not a particularly large percentage of the overall energy consumption; most of the power used is needed to overcome air resistance (drag), as with any other high-speed form of transport.
In the public imagination, "maglev" often evokes the concept of an elevated monorail track with a linear motor. This can be misleading. While several maglev systems are monorail designs, not all maglevs use monorails,and not all monorail trains use linear motors or magnetic levitation. Some railway transport systems incorporate linear motors but only use electromagnetism for propulsion, without actually levitating the vehicle. Such trains (which might also be monorail trains) are wheeled vehicles and not maglev trains. 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.
The highest recorded speed of a maglev train is 581 km/h (361 mph), achieved in Japan by Central Japan Railway Company's (JR Central) MLX01 superconducting maglev in 2003, 6 km/h (3.7 mph) faster than the conventional wheel-rail speed record set by the TGV
Differences in construction costs can affect chances for profitability. Maglev advocates claim that with conventional railway trains, at very high speeds, the wear and tear from friction along with the concentrated pounding from wheels on rails accelerate equipment deterioration and prevent mechanically-based train systems from achieving a maglev-based train system's high level of performance and low levels of maintenance;. Indeed, it was concerns about maintenance and safety that convinced Chinese authorities to announce a slowing down of all new conventional high-speed trains to 300 km/h (190 mph).
There are presently only two commercial maglev transport systems in operation, with two others under construction. In April 2004, Shanghai began commercial operations of the high-speed Transrapid system. Beginning March 2005, Japan began operation of the HSST "Linimo" line in time for the 2005 World Expo. In its first three months, the Linimo line carried over 10 million passengers. South Korea and the People's Republic of China are both building low speed maglev lines of their own design, one in Beijing and the other at Seoul's Incheon Airport