The fastest train in the world is Japanese: it does not touch the tracks and uses superconductors ! Indeed, this train levitates a few inches above the tracks thanks to a technology that uses strong magnetic fields created by superconducting coils located and cooled on board. This train is not marketed but it has been tested on a 40-km-long railway in Yamanashi region (Japan).
The wagons go at 500 km/h with passengers, and the speed record of 581 km/h won in 2003 beats that of the TGV. The marketing development of these trains is still limited because of the cost of the special tracks that are needed, but it is currently studied in many cities. A railway line between Tokyo and Osaka should be built, but it will take a few more years…
To make trains levitate, there are other technologies, such as electrodynamic sustentation, which is used for the transrapid in Shanghai. You can even build your own superconducting train, but it will not reach 581 km/h!
