maglev

A maglev train uses powerful electromagnets to lift and propel itself above a guideway, eliminating friction from wheel-rail contact. The vehicle hovers 10 centimeters or more above the track, suspended by repulsive or attractive magnetic forces between the train's magnets and conducting coils embedded in the guideway. This levitation removes the primary source of rolling resistance, allowing maglev systems to achieve speeds of 400 to 600 kilometers per hour in commercial operation, with experimental prototypes exceeding 600 km/h.

Two competing maglev technologies exist. Electromagnetic suspension (EMS) uses attractive force, pulling the train upward against the guideway from below; the train is inherently stable but requires sophisticated active controls to maintain gap distance. Electrodynamic suspension (EDS) uses repulsive force, pushing the train away from the guideway; this is passive and stable at high speeds but requires wheels or supports for low-speed motion. EMS systems dominate current deployments, including the Shanghai Maglev (since 2002) and Japanese prototypes.

Energy and infrastructure demands

Maglev systems consume roughly 30 to 40 percent less energy per passenger-kilometer than conventional high-speed rail at peak speeds, but the guideway itself is expensive to construct, maintain, and retrofit. Guideway costs typically exceed those of conventional track by three to five times. The system requires dedicated corridors with strict clearances and cannot easily share infrastructure with conventional rail. Lateral stability and weather resilience (wind loads, rain contact with exposed magnets) add complexity not present in wheeled systems.

The term 'maglev' is a portmanteau of 'magnetic levitation,' coined in the 1960s as electromagnetic suspension technology matured. The concept addressed fundamental limits of wheel-rail contact: adhesion limits, wear, noise, and vibration. While maglev offers dramatic speed and efficiency gains, practical deployment has been limited to high-density corridors where capital investment can be amortized over heavy traffic. Passenger acceptance remains high in regions with operational systems.