Maglev, as you probably know, stands for magnetic levitation. There are many varieties of maglev, but in Japan’s case the L0 Series trains have superconducting magnets on the carriage and wire coils along the track. To begin with, the train rolls along on rubber wheels, but once it reaches 150 kph (93 mph), the magnetic field induction effect created by the superconducting magnets passing by the coils creates enough current to levitate the train 10cm (4 in) off the track. Because the coils on each side of the track are connected, the induced current automatically stabilizes the train if it moves off-center. A second set of coils provides linear motor propulsion (a lot like a railgun).
The main advantage of maglev is that, except when starting off, it doesn’t use wheels. Wheels introduce a whole raft of engineering concerns that are difficult and costly to overcome, such as massive wear and tear, breaking distances, and frictional losses. Levitation, due to the complete lack of friction, is quieter and smoother for passengers. The lack of wheels also means that the system requires much less maintenance, and can also operate under almost any weather condition. Despite these advantages, though, it still isn’t clear if maglev is commercially viable: While the running costs are significantly lower than wheel-rail systems, the initial installation cost is massively expensive. The Chuo Shinkansen Tokyo-Osaka maglev line, which is scheduled for completion in 2027, is currently estimated to cost nine trillion yen, or around $91 billion.