Rail Shock is an extreme-sports vehicle that uses the urban tramrails and its overhead wiring for locomotion. Based on an underground movement of adrenaline junkies it allows them to complete in illegal street races. The rider is pulled in a similar way to a waterskier. 
 
The one wheeled vehicle is powered  by a pantograph at the top of the pole which conductions 600VDC of the overhead wiring to a switch power supply that regulates the current to the 48V DC required for the wheel hub motor. A motor control unit allows the rider to adjust the speed.
 
The vehicle is held in the rails by guiding wheels mounted on four side arms. The wheel motor is located between the rails for the best grip and acceleration.
 
For full design experimentation see post49
The movie – post 61