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
Upminster (UK Parliament constituency) Hilldene, and Upminster. 1983-1997: The London Borough of Havering wards of Ardleigh Green, Cranham East, Cranham West, Emerson Park, Gooshays, Harold Wood, Heaton, Hilldene, and Upminster. 1997-2010: The London Borough of Havering wards of Cranham East, Cranham West, Emerson Park, Gooshays, Harold Wood, Heaton, Hilldene, and Upminster. Upminster was the easternmost constituency of the London Borough of Havering, and of Greater London. The constituency was oddly shaped and covered both the wealthiest and the poorest parts of the borough while being London's least ethnically diverse constituency. The constituency included the Upminster suburb of Cranham. The boundary to the north extended