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
Safety on the London Underground Safety on the London Underground This article is primarily concerned with accidents on the London Underground network, which carries around a billion passengers a year. Statistically, there is just one fatal accident for every 300 million journeys. There are several safety warnings given to passengers, such as the traditional 'mind the gap' announcement and the regular announcements for passengers to keep behind the yellow line. Relatively few accidents are caused by overcrowding on the platforms, and staff monitor platforms and passageways at busy times preventing people entering the system if they become overcrowded. Most fatalities on the network are suicides.