London Underground and the mechanisms are regularly degreased to lower the potential for fires. The only wooden escalator not to be replaced was at Greenford station, which remained until October 2015 when TfL replaced it with the first incline lift on the UK transport network. There are 426 escalators on the London Underground system and the longest, at , is at Angel. The shortest, at Stratford, gives a vertical rise of . There are 184 lifts, and numbers have increased in recent years because of investment making tube stations accessible. Over 28 stations will have lifts installed over the next 10 years,
Aldwych tube station not been officially approved. Because it was a self-contained section of the London Underground that was closed outside weekday peak hours, Aldwych station and the branch line from Holborn were popular locations for filming scenes set on the Tube even before their closure. Since the branch's closure in 1994, its use in film productions has continued, with the station appearing as itself and, with appropriate signage, as other stations on the network. The track and infrastructure are maintained in operational condition, and a train of ex-Northern line 1972 tube stock is permanently stabled on the branch. This train can be