third rail(a method of providing electric power to a railway locomotive or train, through a semi-continuous rigid conductor placed alongside or between the rails of a railway track. It is used typically in a mass transit or rapid transit system, which has alignments in its own corridors, fully or almost fully segregated from the outside environment. Third rail systems are often supplied from direct current electricity.: Third-rail systems are a mean of providing electric traction power to trains using an additional railwikipedia.orgIrdeng01)
