What is third rail system? All Questions › Category: Electric Vehicle › What is third rail system? 0 Vote Up Vote Down Chetan Shidling asked 5 years ago I need short information. 1 Answers 0 Vote Up Vote Down Chetan Shidling answered 5 years ago The third rail system is mostly used in metro station. In third rail system, one more extra rail wll be provided i.e., third rail. The third rail carries dc supply to supply to metro trains.