London Underground Piccadilly Line

London Underground Piccadilly Line is a Transport for London operated tube line in London, England. Running between Cockfosters and Acton Town, it divides into two branches with one to Heathrow Airport and the other to Uxbridge in north-west London, with some services terminating at Rayners Lane. It is coloured dark blue (officially "Corporate Blue", Pantone 072) on the Tube map.

It is the fourth-busiest line on the Underground network with over 210 million passenger journeys in 2011/12. It is mainly a deep-level line, with a number of surface sections, mostly in its western-most parts. It is named after Piccadilly, the street above it between Hyde Park Corner and Piccadilly Circus. Some of its stations are shared with the District line (between South Kensington and Ealing Common) and some are shared with the Metropolitan line (from Rayners Lane to Uxbridge). It is the second-longest line on the system after the Central line, and with 53 stations only the District line has more stops.

The Piccadilly line serves many of London's key tourist attractions including the British Museum (Russell Square), the numerous museums around South Kensington, Harrods (Knightsbridge), Hyde Park and Buckingham Palace(within walking distance of Green Park station), Leicester Square (with its own station) and Covent Garden (also with its own station).

History
The Piccadilly line began as the Great Northern, Piccadilly & Brompton Railway (GNP&BR), one of several railways controlled by the Underground Electric Railways Company of London (UERL), whose chief director was Charles Tyson Yerkes, although he died before any of his schemes came to fruition.

The GNP&BR was formed from the merger of two earlier, but unbuilt, tube-railway companies taken over in 1901 by Yerkes' consortium: the Great Northern & Strand Railway (GN&SR) and the Brompton & Piccadilly Circus Railway (B&PCR). The GN&SR's and B&PCR's separate routes were linked with an additional section between Piccadilly Circus and Holborn. A section of the District Railway's scheme for a deep-level tube line between South Kensington and Earl's Court was also added in order to complete the route.

When the GNP&BR was formally opened on 15 December 1906, the line ran from the Great Northern Railway's station at Finsbury Park to the District Railway's station at Hammersmith.

On 30 November 1907, the short branch from Holborn to the Strand (later renamed Aldwych) opened; it had been planned as the last section of the GN&SR before the amalgamation with the B&PCR. In 1905 (and again in 1965), plans were made to extend it the short distance south under the River Thames to Waterloo, but this never happened. Although built with twin tunnels, single track shuttle operation became the norm on the branch from 1918 on, with the eastern tunnel closed to traffic.

From the 1920s onwards there had been severe congestion at the line's northern terminus, Finsbury Park, where travellers had to change on to trams, buses and LNER main line trains for destinations in North London and North East London. There had been deputations made to Parliament asking for an early extension of the line either towards Tottenham and Edmonton or towards Wood Green and Palmers Green.

The early 1930s was a time of recession, and in order to relieve unemployment, government capital was made available. The chief features of the scheme were an extension northwards from Finsbury Park to Cockfosters. It was also planned to build a station between Manor House and Turnpike Lane at the junction of Green Lanes and St Ann's Road in Harringay, but this was stopped by Frank Pick, who felt that the bus and tram service at this point was adequate. However, a 'Ventilation station', in similar architectural style to tube stations of the time was provided at the site, and is visible today. There was also some opposition from the London and North Eastern Railway to the line. The extension began from Finsbury Park to a point a little south of Arnos Grove. The total length of the extension is 12 km (7.5 mi): it cost £4 million to build and was opened in sections as follows: In 1975, a new tunnel section was opened to Hatton Cross from Hounslow West. Hounslow West became a tunnel section station. In 1977, the branch was extended to Heathrow Central. This station was renamed Heathrow Terminals 1, 2, 3 in 1984, with the opening of a one-way loop serving Heathrow Terminal 4, south of the central terminal area. To reflect the demolition of Terminal 1 in June 2015, it was renamed again as Heathrow Terminals 2 & 3.
 * 19 September 1932: to Arnos Grove
 * 13 March 1933: to Enfield West (now Oakwood), in conjunction with the westward extension to Hounslow West
 * 19 July 1933: completion to Cockfosters

On 30 September 1994, the service to Aldwych was withdrawn and the branch closed down on the same day as the Central Line's Ongar branch.

From 7 January 2005 until 17 September 2006, the loop via Heathrow Terminal 4 was closed to allow the connection of a spur line to the now operational Heathrow Terminal 5 station. All underground services reverted to two-way working into Terminals 2 & 3, which again became the temporary terminus; shuttle buses served Terminal 4 from the Hatton Cross bus station. For a brief period in summer 2006, the line terminated at Hatton Cross and shuttle buses also ran to Terminals 2 & 3 while the track configuration and tunnels were altered for the Terminal 5 link from that station. The station at Terminal 5 opened on 27 March 2008 on the same day Terminal 5 opened.

From 2025, new nine carriage New Tube for London trains will begin to replace the current 1973 Stock. By 2027/2028, the line is expected to be converted into a full New Tube for London operation.

Current Route
The Piccadilly Line operates via these primary locations. Heathrow Terminals branch Uxbridge branch
 * Cockfosters
 * Oakwood
 * Southgate
 * Arnos Grove
 * Bounds Green
 * Wood Green
 * Turnpike Lane
 * Manor House
 * Finsbury Park
 * Arsenal
 * Holloway Road
 * Caledonian Road
 * King's Cross St Pancras
 * Russell Square
 * Holborn
 * Covent Garden
 * Leicester Square
 * Piccadilly Circus
 * Green Park
 * Hyde Park Corner
 * Knightsbridge
 * South Kensington
 * Gloucester Road
 * Earl's Court
 * Barons Court
 * Hammersmith
 * Turnham Green (Peak hours only)
 * Acton Town
 * South Ealing
 * Northfields
 * Boston Manor
 * Osterley
 * Hounslow East
 * Hounslow Central
 * Hounslow West
 * Hatton Cross
 * Heathrow Terminal 4
 * Heathrow Terminals 1, 2 & 3
 * Heathrow Terminal 5
 * Ealing Common
 * North Ealing
 * Park Royal
 * Alperton
 * Sudbury Town
 * Sudbury Hill
 * South Harrow
 * Rayners Lane
 * Eastcote
 * Ruislip Manor
 * Ruislip
 * Ickenham
 * Hillingdon
 * Uxbridge