Circle line (London Underground) with the other London Underground sub-surface lines: the Hammersmith & City line from Hammersmith to just before Aldgate; the Metropolitan line from Baker Street to Aldgate; and the District line from Tower Hill station to Edgware Road station. The line is electrified with a four-rail DC system: a central conductor rail is energised at and a rail outside the running rail at , giving a potential difference of . The running rails are not electrified. Much of the double track railway from the Hammersmith terminus to Westbourne Park station is on a high brick viaduct. East of Westbourne Park the
Suicide on the London Underground inform the public), "person on the track", "passenger action," but most commonly "one under", or "jumper" — well-known phrases across the network. Those who survive are often charged with offences such as "endangering safety on the railway" and "obstruction of trains with intent". About half of the stations, mostly those actually underground, have a pit under the tracks. Originally constructed to drain water, they have now been shown to reduce the number and severity of injuries and deaths, although not to eliminate them: as a Transport for London (TfL) spokesperson has said, "people fall into [the pits] and the train