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 built-up area of London since the 1930s and is contiguous with Cranham to the east and Hornchurch to the west. To the north and south there is open land that forms part of the Metropolitan Green Belt and there are open spaces formed by Upminster Golf Club and Upminster Hall Playing Field to the north, Upminster Park and Clock House Gardens to the south, and the Ingrebourne Valley linear park to the south west. The town is effectively divided into north and south parts by the railway line. The north is predominantly residential, with the southern part containing the main