S Stock

The London Underground S Stock is a fleet of subsurface rolling stock used on the London Underground since 2010. Manufactured by Bombardier Transportation's Derby Litchurch Lane Works, the S Stock was ordered to replace the A60, A62, C69, C77 and D78 stock on the Metropolitan, District, Hammersmith & City, and Circle lines, which all date back to the 1960s and 1970s. The order consists of a standardised fleet of 191 trains (1,395 cars), with 1 additional train (actually a 7-car train 21567-568) ordered as a part of Metropolitan line extension to Watford Junction (192 trains = 1,402 cars). Two additional non de-icing cars were subsequently built, (23384, 23386) as the original de-icing cars had been inserted into earlier trains (192 trains = 1,402 cars + 2 = 1,404). The stock has two types, S7 and S8, serving different lines, with differences in the arrangement of seating and number of cars. Both types have air-conditioning and low floors to ease accessibility for disabled people, and it is also possible for a passenger to walk from one car to the next while the train is moving, unlike older trains on the network.

The order is said to be the biggest single rolling-stock order in Britain at, according to Transport for London, a cost of £1.5 billion.undefined

Passenger service began on the Metropolitan line in July 2010, the Hammersmith & City line in July 2012, and the Circle and District lines in September 2013. The S Stock completely replaced the A Stock on the Metropolitan line in September 2012, and the C Stock on the Circle and Hammersmith & City lines in February 2014, and started operating on the District line in June 2014; it fully replaced the D Stock on the rest of the District line in April 2017.

The S Stock Trains have a family relation to the Victoria Line's 2009 Stock.