Watford DC line

The Watford DC line is a suburban railway line from London Euston to Watford Junction in Greater London and Hertfordshire. The line is shared by services on London Underground's above-ground section of the Bakerloo line between Harrow & Wealdstone and Queen's Park, and London Overground's Lioness line which runs over its entire length.

The line runs beside the West Coast Main Line (WCML) for most of its length. The rolling stock used on the line are the London Overground Class 710 "Aventras" made by Bombardier and the London Underground 1972 Stock.

The Watford New Line was opened in stages by the London and North Western Railway from 15 June 1912 as part of a wider scheme of suburban capacity improvement and electrification. Delayed by World War I, full electric service from Watford Junction to Euston commenced on 10 July 1922.

The "DC" in the title refers to line being electrified using direct current. This was done in the early twentieth century with conductor rails to be compatible with the four-rail system used by the Underground and, at the time, the North London Line; currently, the line uses a third rail system, with a fourth rail available on the section shared with the Bakerloo line. By contrast, the WCML uses overhead alternating current.