Central line (London Underground) that the transport benefits of a Park Royal station on the Central line are not sufficiently high to justify the costs of construction. Central line (London Underground) The Central line is a London Underground line that runs through central London, from , Essex, in the north-east to and in the west. Coloured red on the Tube map, the line serves 49 stations over , which makes it the longest Tube line. It is also one of only two lines on the Underground network to cross the Greater London boundary, the other being the Metropolitan line. One of London's deep-level railways,
North London line and London King's Cross stations, so since then this link has only been used for freight trains. It too was singled concurrent with the AC electrification of the eastern part of the North London line. Most of the line runs in a curve across north London. Only and stations at the western end are south of the River Thames. The river crossing is made by Kew Railway Bridge on tracks which are shared with the London Underground District line. The location of the eastern extremity has varied over the years. Between 1944 and 1986, it was at Broad Street station,