Magnetic levitation train

A magnetic levitation train, or maglev, is a train that floats above a guideway on magnetic forces and is also pushed forward by them, so it runs with no contact between vehicle and track. Because there are no wheels rolling on rails, there is no rolling friction, and the train can reach high speeds with little mechanical wear. Only a handful of maglev lines operate commercially, and the best known links Shanghai’s Pudong International Airport with the city.

History of the magnetic levitation train

Engineers proposed magnetic suspension for transport in the early twentieth century, but practical designs depended on later advances in electronics and magnets. The U.S. Department of Energy (DOE) traces maglev to technology pioneered at Brookhaven National Laboratory, where James Powell and Gordon Danby received the first patent for a magnetically levitated train design in the late 1960s. According to DOE, the idea came to Powell as he sat in a traffic jam and wondered whether there was a better way to travel on land, and he imagined using superconducting magnets to levitate a train car.

Germany and Japan developed rival systems in the decades that followed. The Transrapid system, built by Transrapid International with technology from a consortium of Siemens and ThyssenKrupp, was selected for the Shanghai line. Guinness World Records reports that the train had its official maiden run on December 31, 2002 and was built in under two years. Japan’s Central Japan Railway Company (JR Central) developed its own superconducting maglev, called SCMAGLEV, which the company says can realize commercial service at a speed of 500 kilometers per hour.

How a magnetic levitation train works

Every maglev has to do three things: lift the train, keep it centered on the guideway, and propel it. Magnetic forces do all three, and they are controlled by electronics.

DOE explains one design in which superconducting magnets suspend a train car above a U-shaped concrete guideway. The magnets are cooled to extreme temperatures, which, as DOE notes, allows them to generate fields up to ten times stronger than ordinary electromagnets, enough to suspend and propel a train. These fields interact with simple metallic loops of conductive material, such as aluminum, set into the guideway walls. When a magnetic field moves past a loop, it induces a current that creates its own field.

Three sets of loops carry out three tasks. One creates a field that makes the train hover about 5 inches above the guideway. A second keeps the train stable from side to side, and in both cases magnetic repulsion pushes the train back toward the best position if it drifts. The third set is a propulsion system run by alternating current, in which both magnetic attraction and repulsion move the train along.

This propulsion works like a linear electric motor, with the motor laid flat along the track instead of rolled into a cylinder. Changing the frequency of the current in the guideway changes the speed of the train. The strong fields explain why superconductivity is so useful in this design. A superconductor can carry the large currents involved without wasting energy as heat, though it must be kept cold.

Types of maglev systems

Maglev designs are usually grouped by how they float. Electromagnetic suspension (EMS) uses electromagnets on the vehicle that are attracted up toward the underside of a steel guideway. The gap is small, so sensors and controls adjust the current continuously to hold it steady. The Transrapid line in Shanghai uses this approach.

Electrodynamic suspension (EDS) relies on repulsion. Magnets on the vehicle induce currents in guideway coils or loops, and the repulsion that results lifts the train. The design described by DOE and the Japanese SCMAGLEV belong to this family. A feature of EDS is that the train needs some speed before it floats, so it rides on wheels at low speed.

A third approach, sometimes called Inductrack, uses permanent magnets in a special arrangement and needs no power for levitation. It is mainly at the test stage.

Applications of magnetic levitation trains

The Shanghai line is the leading example. Guinness World Records reports that the train covers the 30 kilometer (18 mile) trip in about 8 minutes, with a top speed of 431 kilometers per hour (267.8 miles per hour) on each run, which is a record for regular public service. The same source says the train is claimed to reach 500 kilometers per hour under test conditions but is limited in service by route length and the spacing of stops.

DOE notes that maglev systems are also in operation in Japan and South Korea, and that routes have been studied in the United States to connect cities such as Baltimore and Washington, D.C. Many shorter lines serve airports and urban corridors, where the quiet ride and low maintenance of a contactless train are useful. In Japan, JR Central is proposing its SCMAGLEV system to overseas markets.

Advantages and disadvantages of magnetic levitation trains

The advantages are speed, smoothness and low wear. With no wheel-to-rail contact, there is little friction, which also cuts noise from the running gear and reduces the parts that wear out. Acceleration and climbing ability can be high, and power is supplied through the guideway, so the train needs no engine on board.

The disadvantages are mostly cost and compatibility. A maglev needs a dedicated guideway that cannot be shared with conventional trains, so a line cannot use existing track or stations. Construction costs are high, and the number of lines in service is small, which keeps equipment costs high too. Superconducting designs need cryogenic cooling, and long routes in difficult terrain require extensive tunneling or elevated structures.

Energy use rises steeply at the highest speeds because of air resistance, so the energy advantage over other trains is not guaranteed at very high speeds.

Maglev vs. high-speed rail

Conventional high-speed rail uses steel wheels on steel rails and can share track and stations with other services, which lowers the cost of extending a network. Maglev trades that compatibility for the possibility of higher speeds and less mechanical wear. Which is better depends on distance, demand and cost for a given route. The information here is general background and not engineering advice.

Editorially reviewed by Specialty Digest Editorial TeamLast reviewed November 4, 2026Researched and drafted with AI assistanceReport an issue