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,
Oval tube station and the imposing St Mark's Church. The City and South London Railway opened to passengers between Stockwell and King William Street on 18 December 1890, and was both the first standard gauge tube and the first railway to employ electric traction in London. To avoid disturbance of surface buildings the construction of the tube was shield-driven at deep level, and much of the work was done via shafts at station sites which later contained the passenger lifts. Oval tube station was the intended site of one of the attempted London bombings on 21 July 2005. The Oval station, opened as