Third rail

This article is about the power system for railways. For other uses, see Third rail (disambiguation).
"Power rail" redirects here. For the use in power supplies, see Power rail (power supplies).

A British Rail Class 442 third-rail electric multiple unit in Battersea
The contact shoe of a New York City Subway car making contact with the third rail. In the foreground is the third rail for the adjacent track.

A third rail, also known as a live rail, electric rail or conductor rail, is 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 usually supplied from direct current electricity.

Modern tram systems with street-running avoid the risk of electrocution by the exposed electric rail by implementing a segmented ground-level power supply, where each segment is electrified only while covered by a vehicle which is using its power.[1]

The third-rail system of electrification is not related to the third rail used in dual-gauge railways.

  1. ^ Christeller, Reinhard (17 June 2020). "Innovative power supply technologies for traction systems in public transport". Urban Transport. Retrieved 8 February 2022.