The Piccadilly line is a deep-level London Underground line which runs between the west and the north of London with 53 stations on the line. The line serves Heathrow Airport, and some of its stations are near tourist attractions in Central London such as King's Cross, Piccadilly Circus and Buckingham Palace. It has two western branches which split at Acton Town, with the main one towards Heathrow Airport terminals and the other northern branch towards Uxbridge. The District and Metropolitan lines share some sections of track with the Piccadilly line. The line is printed in dark blue (officially "Corporate Blue", Pantone 072) on the Tube map. It is the sixth-busiest line on the Underground network, with nearly 218 million passenger journeys in 2019.
The first section, between Finsbury Park and Hammersmith, was opened in 1906 as the Great Northern, Piccadilly and Brompton Railway (GNP&BR). The station tunnels and buildings were designed by Leslie Green, featuring ox-blood terracotta facades with semi-circular windows on the first floor. When Underground Electric Railways of London (UERL) took over the line, it was renamed the Piccadilly line. Subsequent extensions were made to Cockfosters, Hounslow West and Uxbridge in the early 1930s, when many existing stations on the Uxbridge and Hounslow branches were rebuilt to designs by Charles Holden of the Adams, Holden & Pearson architectural practice. These were generally rectangular, with brick bases and large tiled windows, topped with a concrete slab roof. The western extensions took over certain existing District line services, which were fully withdrawn in 1964.
Stations in central London were rebuilt to cater for a higher volume of passenger traffic. To prepare for the Second World War, some stations were equipped with shelters and basic amenities, and others with blast walls. Construction of the Victoria line, the first section of which opened in 1968, helped to relieve congestion on the Piccadilly line; some sections of the Piccadilly had to be rerouted for cross-platform interchange with the new line. Several plans were made to extend the Piccadilly line to serve Heathrow Airport. The earliest approval was given in 1967, and the Heathrow extension opened in stages between 1975 and 1977. This served only Terminals 2 and 3 and the former Terminal 1. The line was extended again twice, to Terminal 4 via a loop in 1986, and to Terminal 5 directly from the main terminal station in 2008.
This line has two depots, at Northfields and Cockfosters, with a group of sidings at several locations. There are crossovers at a number of locations, some of which allow trains to switch to different lines. The Piccadilly line's electric power was formerly generated at Lots Road Power Station. This was taken out of use in 2003, and the line is now powered from the National Grid network. 1973 Stock trains are used on the line, 78 of which are needed to operate a 24 trains per hour (tph) service (a train every minutes) during peak hours. These trains are due to be replaced by 2024 Stock in 2026.
Route
The Piccadilly line is a long north–west line, with two western branches splitting at Acton Town, serving 53 stations. At the northern end, Cockfosters is a four-platform three-track terminus, and the line runs at surface level to just south of Oakwood. Southgate station is in a tunnel, with tunnel portals to the north and south. Due to the difference in terrain, a viaduct carries the tracks through Arnos Park to Arnos Grove. The line then descends into twin tube tunnels, passing through Wood Green, Finsbury Park and central London. The central area contains stations close to tourist attractions, such as the London Transport Museum, Harrods, Buckingham Palace and Piccadilly Circus. The tunnel ends east of Barons Court, where the line continues west, parallel to the District line, to Acton Town. A flying junction, in use since 10 February 1910, separates trains going to the Heathrow branch from the Uxbridge branch.
The Heathrow branch remains at surface level until the eastern approach to Hounslow West station, where it enters a cut-and-cover tunnel. West of Hatton Cross, the line enters tube tunnels to Heathrow Airport and branches to the Terminal 4 loop or to a terminus at Terminal 5. On the Uxbridge branch, the line shares tracks with the District line between Acton Town and south of North Ealing. Traversing terrain with cuttings and embankments, it continues to Uxbridge, sharing tracks with the Metropolitan line between Rayners Lane and Uxbridge. The distance between Cockfosters and Uxbridge is .
Map
upright=3.0|thumb|center|Geographically accurate path of the Piccadilly line from Heathrow Airport and Uxbridge in the west to Cockfosters in [[north London.|alt=A line map, marked with the location of tube stations showing two parallel branches on the left an upwards vertical section on the right]]
History
The Piccadilly line began as the Great Northern, Piccadilly and 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 the first section of the line opened. It currently runs on tracks built by The GNP&BR, the District Railway (DR) and the Metropolitan Railway (Met), and received major extensions in the 1930s and 1970s.
The GNP&BR was formed from the merger of two earlier, but unbuilt, tube-railway companies taken over in 1901 by Yerkes's 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 and . A section of the DR's scheme for a deep-level tube line between and was also added in order to complete the route. This finalised route, between Finsbury Park and Hammersmith stations, was formally opened on 15 December 1906. On 30 November 1907, the short branch from Holborn to the Strand (later renamed ) opened; it had been planned as the last section of the GN&SR before the amalgamation with the B&PCR.
Initial ridership growth was low due to high use of new electric trams and motor buses. Financial stability was an issue, and as a result the company heavily promoted their railways via a new management team. UERL also agreed with other independent railway companies such as the Central London Railway (CLR, now part of the Central line) to jointly advertise a combined network known as the Underground. On 1 July 1910, the GNP&BR and the other UERL-owned tube railways (the Baker Street and Waterloo Railway and the Charing Cross, Euston and Hampstead Railway) were merged by the London Electric Railway Amalgamation Act 1910 (10 Edw. 7 & 1 Geo. 5. c. xxxii) to become the London Electric Railway Company (LER). The Underground railways still suffered financial issues, and to address this, the London Passenger Transport Board was established on 1 July 1933.
There were significant station layout changes in the 1910s and 1920s. On 4 October 1911, Earl's Court had new escalators installed connecting the District and Piccadilly lines. They were the first to be installed on the Underground. On 10 December 1928, a rebuilt Piccadilly Circus station, designed by Charles Holden, was opened. This included a new booking hall located below ground and eleven escalators, replacing the original lifts.
One of the shafts at Holloway Road station was used as an experiment for spiral escalators, but never used. An experiment to encourage passengers to step on the escalator three at a time at Manor House station was trialled. It failed due to opposition and potential dangers pointed out by the public.
Extension to Cockfosters
thumb|One of the ventilation panels at Wood Green station platforms
While early plans to serve Wood Green (specifically Alexandra Palace) existed since the 1890s as part of the GN&SR, this section to Finsbury Park was later dropped from the GNP&BR proposal in 1902 when the GN&SR was merged with the B&PCR. In 1902, as part of an agreement for taking over the GN&SR, the Great Northern Railway (GNR) imposed a sanction<!--no suitable wikilink available--> on Yerkes to abandon the section north of Finsbury Park and they would construct the terminus below ground. Finsbury Park remained as an overcrowded terminus of the line, and was described as "intolerable". Many passengers arriving at both stations had to change onto buses, trams, and suburban rail services to complete their journeys further north. The GNR attempted to address this issue by considering electrification several times, but to no avail due to shortage of funds. Meanwhile, the LER proposed an extension in 1920 but was overruled by the GNR, which was widely regarded as "unreasonable". In 1923, a petition by the Middlesex Federation of Ratepayers to repeal the 1902 act of Parliament emerged. It was reported that a "fierce exchange of arguments" occurred during a parliamentary session in March 1924 to request this change.