Maglev
Every train ever built had one thing in common: it pressed down on something. A maglev doesn't. It floats a centimetre or so above its guideway on nothing but magnetic force, and a motor with no moving parts shoves it forward. Take the wheels away and you take away the thing that was holding it back.
How it works
Maglev — short for magnetic levitation — swaps the steel wheel-on-steel rail for magnets and a track called a guideway. The magnets do two jobs at once. First they levitate the vehicle, holding it a small gap clear of the guideway so nothing physically touches. Then a linear motor — an ordinary electric motor unrolled flat along the track — drives it forward by pushing a travelling magnetic wave against the train's onboard magnets. The propulsion lives in the track itself, not in the vehicle.
Because nothing rolls or rubs, there is no rolling resistance and no contact to wear out. The only thing left to fight at speed is aerodynamic drag — the air. That is why maglev can reach speeds where steel wheels would slip and shake themselves apart.
Two families of levitation
Nearly every maglev belongs to one of two families, and they float in opposite ways:
- EMS (electromagnetic suspension) pulls the train up by attraction. Electromagnets on the vehicle reach under a steel rail and are drawn toward it; fast electronics constantly trim the current to hold the gap, because magnetic attraction is inherently unstable. Germany's Transrapid — the technology under the Shanghai Maglev — works this way and levitates even while stopped.
- EDS (electrodynamic suspension) pushes the train up by repulsion. Superconducting magnets on the vehicle induce currents in guideway coils as it moves, and those currents repel the train and lift it. Japan's SCMaglev uses this. It is naturally stable but makes no lift when slow, so the train rides on rubber tyres until it is fast enough to float.
The magnetic details — why attraction needs active control and repulsion doesn't — get their own levitation concept page.
The speed records
For all the exotic physics, only a handful of maglevs carry passengers. The Shanghai Maglev, running since 2004, is the fastest train in commercial service on Earth: it covers a 30 km airport run at a peak of 431 km/h, holding top speed for barely a minute. Japan has gone faster still on test track — an L0 series SCMaglev set the world record for a crewed train at 603 km/h in 2015, and the Chūō Shinkansen line will run it at 500 km/h in service.
Why it hasn't spread
If maglev is faster and smoother, why isn't it everywhere? Cost and compatibility. A maglev needs an entirely new, purpose-built guideway — the levitation and propulsion are baked into the track, so it can share nothing with the existing network. Conventional steel-wheel high-speed rail can run onto legacy tracks to reach city-centre stations; a maglev cannot roll a metre on ordinary rail. Every kilometre must be built from scratch, and the price is steep.
Meanwhile steel-wheel high-speed rail keeps getting faster — routinely 300–350 km/h in service — which narrows maglev's edge while staying far cheaper to build and connect. So maglev remains a small club of showcase and short-haul lines rather than a replacement for the railway.