Editing Piccadilly line (section)

===Westward extensions===
The [[Hounslow West tube station|Hounslow West]] (then Hounslow Barracks) extension of the Piccadilly line, together with the [[Uxbridge]] extension, aimed to improve services on the [[District line]] which at the time were serving both branches from [[Acton Town tube station|Acton Town]] (then Mill Hill Park).{{sfn|Horne|2007|p=42}}{{refn|The Hounslow & Metropolitan Railway originally opened a shuttle service between Mill Hill Park and [[Hounslow Town tube station|Hounslow Town]] on 1 May 1883, with a single-track branch to Hounslow Barracks which opened on 21 July 1884. The route to Hounslow Town eventually closed on 2 May 1909. The District Railway took over the branches in 1903.{{sfn|Horne|2007|pp=42,46}}|group=note}} The Uxbridge extension followed along existing routes on the DR and Met. The DR opened a spur from [[Ealing Common tube station|Ealing Common]] to [[South Harrow tube station|South Harrow]] in June 1903. The Met opened its extension to Uxbridge in July 1904.{{sfn|Horne|2007|pp=42–45}} Through trains of the DR were eventually extended to Uxbridge on 1 March 1910, henceforth sharing tracks with the Met between [[Rayners Lane tube station|Rayners Lane]] and Uxbridge.{{sfn|Horne|2007|pp=44–45}}{{refn|The Ealing & South Harrow Railway (E&SHR) was approved in 1894 and completed in 1899 after approximately a two-year construction period. Insufficient funds from the DR delayed its opening. On the other hand, the [[Harrow & Uxbridge Railway]] (H&UR) was proposed in 1896 and authorised a year later.{{sfn|Simpson|2003|p=97}} The Met offered to fund the line, with conditions to take over the Rayners Lane to [[Uxbridge tube station|Uxbridge]] section of the H&UR. Agreement was reached in 1899, with the Met also constructing the connection from South Harrow to Rayners Lane, whilst allowing up to three trains an hour from the DR between South Harrow and Uxbridge.{{sfn|Horne|2003|p=26}} Construction began in 1901, and the Met opened its extension to Uxbridge on 4 July 1904.{{sfn|Horne|2007|pp=42–45}}|group=note}}

The viaduct from Studland Road Junction west of Hammersmith to [[Turnham Green tube station|Turnham Green]] was quadrupled on 3 November 1911. The [[London and South Western Railway]] (L&SWR) used the northern pair of tracks while the District Railway used the southern pair.{{sfn|Horne|2007|pp=46–47}} The LER proposed an extension in November 1912 to [[Richmond station (London)|Richmond]] due to available capacity to the west and the fact that passenger interchanges were large at Hammersmith. It would connect with the L&SWR tracks at Turnham Green.<ref>{{London Gazette |date=22 November 1912|issue=28665|pages=8798–8801}}</ref> It was approved as the [[London Electric Railway Act 1913]] ([[3 & 4 Geo. 5]]. c. xcvii) on 15 August 1913,<ref>{{London Gazette|date=19 August 1913|issue=28747|pages=5929–5931}}</ref> but [[World War I]] resulted in no works done on the extension.{{sfn|Horne|2006|p=56}} A parliamentary report of 1919 recommended through running to Richmond and [[Ealing]].{{sfn|Barker|Robbins|1974|p=252}} The Richmond extension plan was revived in 1922 by [[Albert Stanley, 1st Baron Ashfield|Lord Ashfield]], the Underground's chairman. It was decided that the Piccadilly line extension was favourable over the CLR's as it was cheaper and had more capacity available.{{sfn|Horne|2007|pp=48–49}}{{refn|The CLR also had its Richmond extension proposal passed on the same day as the LER's. Nothing was done either.{{sfn|Horne|2007|p=48}} The L&SWR section ceased operation in 1916 and its ownership was transferred to the [[Southern (Govia Thameslink Railway)|Southern Railway]] in 1923.{{sfn|Horne|2006|p=55}} The CLR, by the 1920s, had capacity constraints due to increased patronage from Ealing and congestion in the central section.{{sfn|Horne|2007|pp=48–49}}|group=note}} By 1925, the [[District line]] was running out of capacity west of Hammersmith, where services were headed to South Harrow, Hounslow Barracks, Richmond and [[Ealing Broadway station|Ealing Broadway]]. Demand was also low on the South Harrow branch because of infrequent services and competition among other rail lines in the vicinity of each station. This prompted the Piccadilly line extension to be an express service between Hammersmith and Acton Town, with the future [[Heathrow Airport]] extension safeguarded in 40 years' time.{{sfn|Horne|2007|p=51}} The Piccadilly line would run on the inner pair of tracks, and the District line on the outer.{{sfn|Barker|Robbins|1974|p=252}} Permission was granted to quadruple tracks to Acton Town in 1926 in conjunction with permit renewal for the extension. The Richmond extension never happened, but provisions allocated would allow this option to be revisited later.{{sfn|Horne|2007|pp=51,52}} Extensions would instead be to Hounslow Barracks and South Harrow, taking over DR services to the latter, with an estimated cost of £2.3&nbsp;million.{{sfn|Horne|2007|pp=50–51,66}}{{refn|The District line instead focused on running trains to Richmond, Ealing Broadway and [[Wimbledon station|Wimbledon]], with the South Harrow to Uxbridge and Acton Town to [[South Acton railway station (England)|South Acton]] shuttles to remain. In October 1930, provision was also made to have rush hour DR services to South Harrow.{{sfn|Horne|2006|pp=52,56}}|group=note}} In 1930, unsuccessful negotiations were made between LER and the Met to extend Piccadilly line trains to Rayners Lane for passengers to change trains.{{sfn|Horne|2007|p=58}}

In 1929, quadrupling was to extend to [[Northfields tube station|Northfields]] for express trains to terminate there. This work was completed on 18 December 1932. Overall works for the extension began in 1931, approximately a year after permission was granted and funded under the Development (Loan Guarantees and Grants) Act 1929 ([[20 & 21 Geo. 5]]. c. 7). The Studland Road Junction area was partially rebuilt, with some of the old viaducts retained to date. The junctions diverging to Richmond were reconfigured at Turnham Green. Reversing facilities were initially designated at the latter, but these were not built.{{sfn|Horne|2007|p=52}} Trial runs of Piccadilly line trains began on 27 June 1932. On 4 July 1932, services were extended to South Harrow, which replaced DR services. Northfields services were introduced on 9 January 1933, and on 13 March, were extended to Hounslow West. On 1 July 1933, the [[London Passenger Transport Board]] (LPTB) was formed, which included the Met, the DR and LER.{{sfn|Wolmar|2005|p=266}} The board decided that there was sufficient demand to run through trains to Uxbridge due to rapidly developing suburbs along the line. The extension of Piccadilly line trains to Uxbridge began on 23 October 1933, but with many trains still reversing at South Harrow. By then, most Piccadilly line trains continued beyond Hammersmith, and District line trains to Hounslow were reduced to off-peak shuttles to Acton Town. An enhanced off-peak Piccadilly line service was introduced on 29 April 1935, cutting off-peak District line services down to the Acton Town–[[South Acton railway station (England)|South Acton]] shuttle.{{sfn|Horne|2006|p=60}} South Harrow short trips proved to be an inconvenience. The solution was to move reversing facilities to Rayners Lane. A new reversing siding was built there in 1935, which allowed some peak hour trains to terminate beginning in May 1936. Regular reversals were fully implemented in October 1943.{{sfn|Horne|2007|pp=54,57–58}} Peak-hour District line trains to Hounslow were fully withdrawn on 9 October 1964.{{sfn|Horne|2006|p=88}}