Modern trains are based on Maglev technology in which trains are magnetically levitated, which runs its EDS Maglev system. There are coils on both sides of wheels. Due to motion of train, current induces in the coil of track which levitate it. This is in accordance with Lenz's law. If train lowers down, then according to Lenz's law, a repulsive force increases due to which train gets uplifted and if it goes much high then there is a net downward force due to gravity. The advantage of Maglev train is that there is no friction between the train and the track, thereby reducing the power consumption and enabling the train to attain very high speeds.
Disadvantages of Maglev train is that as it slows down, t the electromagnetic forces decreases and it becomes difficult to keep levitated and as it moves forward according to Lenz law there is electromagnetic drag force.