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,
Urban rail in the United Kingdom and Western England. Stations within London are served by two or four trains per hour. The London Overground (often shortened to "Overground") is operated by Arriva Rail London under a concession let by Transport for London, which owns the London Underground. The Overground includes the Watford Local, North & West London, East London & South and the Gospel Oak to Barking lines. It is the only National Rail service shown on the London Underground map. All stations are served at least every 20 minutes, with stations between and on the East London Line having 16 trains per hour in each