Motive power is provided by a separate locomotive or individual motors in self-propelled multiple units. Although historically steam propulsion dominated, the most common modern forms are diesel and electric locomotives, the latter supplied by overhead wires or additional rails.
Other energy sources include horses, rope or wire, gravity, pneumatics, batteries, and gas turbines. A train track usually consists of two, three or four rails, with a limited number of monorails and maglev guideways in the mix.
Keron Thomas is primarily known for operating an A train in revenue service for over three hours, when he was sixteen years old. He signed into the 207th Street Yard in Manhattan and proceeded to operate the train that originated at the 207th Street Station. Thomas's actions went unnoticed by the passengers on board the R44-type train, who were safely picked up and discharged at normal station stops along the route.
