Editing Piccadilly line (section)

===Signalling and electricity===
[[File:Lots.road.power.station.london.arp.jpg|thumb|[[Lots Road Power Station]], disused and planned to be redeveloped]]
The line from Cockfosters to Heathrow and South Harrow is controlled from a control centre at [[South Kensington tube station|South Kensington]],<ref name=isgaz1950signalpicc>{{cite news |url= https://www.islingtongazette.co.uk/news/piccadilly-line-trains-still-run-by-obsolete-signalling-system-from-the-1950s-1-5517895 |title=Piccadilly line trains still run by obsolete signalling system from the 1950s |work=Islington Gazette |date=15 May 2018 |last=Gelder |first=Sam |access-date=31 August 2020 |url-status=live |archive-date=31 August 2020 |archive-url= https://web.archive.org/web/20200831074109/https://www.islingtongazette.co.uk/news/piccadilly-line-trains-still-run-by-obsolete-signalling-system-from-the-1950s-1-5517895}}</ref> which replaced the old Earl's Court control centre, which was shared with the District line.<ref>{{cite web |last=Signalman |first=Llangollen |url= https://www.flickr.com/photos/llangollen_signalman/albums/72157637392832414 |title=Earls Court Control Room |publisher=Flickr |date=6 November 2013 |access-date=14 July 2017}}</ref> Rayners Lane signal cabin is responsible for signalling the Piccadilly line from just northwest of South Harrow to Uxbridge, as well as the Metropolitan line joining at Rayners Lane.<ref>{{cite web|last=Signalman |first=Llangollen |url=https://www.flickr.com/photos/llangollen_signalman/albums/72157657032080114 |title=Rayners Lane |publisher=Flickr |date=1 October 2015 |access-date=14 July 2017}}</ref> The signalling system is expected to be upgraded in line with the Deep Tube upgrade, which will increase line frequencies up to 33 tph.<ref name=isgaz1950signalpicc/> Trains may also be able to make a permanent additional stop at Turnham Green following this upgrade.<ref>{{cite news |url= https://www.guardian-series.co.uk/news/18213985.tfl-says-piccadilly-tube-upgrade-number-one-priority/ |title=TfL says Piccadilly Tube upgrade is "number one priority" |date=6 February 2020 |access-date=31 August 2020 |last=Mathewson |first=Jessie |work=East London & West Essex Guardian |url-status=live |archive-date=31 August 2020 |archive-url= https://web.archive.org/web/20200831075525/https://www.guardian-series.co.uk/news/18213985.tfl-says-piccadilly-tube-upgrade-number-one-priority/ }}</ref>

When the line was opened from Finsbury Park to Hammersmith, its [[signalling]] system was identical to the Bakerloo and District lines. Small cabins at each location of crossover installed controlled the signals there. Single lamps displayed track clearance in the form of green or red, with variations of yellow at difficult-to-spot locations. This equipment was supplied by [[Westinghouse Rail Systems|Westinghouse]] and operated using compressed air. The exception was between West Kensington and Hammersmith, where it was controlled by District Railway signal boxes, and had semaphore signals instead.{{sfn|Horne|2007|p=27}}{{sfn|Horne|2006|pp=37–40}} The Piccadilly line extensions resulted in resignalling on tracks west of Barons Court. Signal cabins were adjusted and new ones were added at Hammersmith, Acton Town and Northfields. A mixture of [[Railway semaphore signal|semaphore]] and colour-light signals were used on the four-track section. Signalling was redone on the new Uxbridge branch.{{sfn|Horne|2007|p=57}}{{refn|Most of the existing semaphore signals on the District line branch to South Harrow were replaced with coloured light signals between October and December 1932.{{sfn|Horne|2007|p=57}}|group=note}}

Speed control was introduced at several stations to enhance the signalling system after World War II. This enabled a train to proceed slowly into an occupied platform without stopping in front of another before it departed, thus improving headways. The last semaphore signal, at [[Ealing Common tube station|Ealing Common]], was replaced in November 1953.{{sfn|Horne|2007|p=128}} A control room was built at Earl's Court to centralise supervision of most of the line signalling in the 1960s, while Rayners Lane signal cabin was, and still is, the main control centre of the Rayners Lane to Uxbridge portion;{{sfn|Horne|2007|p=126}} shared with the Metropolitan line.<ref name=cartomap /> 1930s automatic signalling equipment was updated in the 1970s and 1980s.{{sfn|Horne|2007|p=127}}

The UERL built a large power station that would be capable of providing power for the District line and the underground lines planned. Work began in 1902 at Lots Road, by [[Counter's Creek|Chelsea Creek]], and in February 1905 Lots Road Power Station began generating electricity at {{nowrap|{{val|11|u=kV}} {{Fraction|33|1|3}} Hz}}, conveyed by high-voltage cables to substations that converted this to approximately {{val|550|u=V|s=&nbsp;DC}}.{{sfn|Horne|2006|p=40}} On the Piccadilly line, electricity was transmitted via underground ducts to Earl's Court, which was then distributed to different substations.{{sfn|Horne|2007|p=27}}{{refn|Direct traction current was also provided from District line substations at Earl's Court and South Kensington.{{sfn|Horne|2007|p=27}}|group=note}} Power supply for the Cockfosters extension was initially generated by the North Metropolitan Electric Power Supply Company at Wood Green.{{sfn|Horne|2007|pp=78–81}} It was later supplied by Lots Road station. The [[National Grid (Great Britain)|National Grid network]] took over the supply on the Ravenscourt Park to Uxbridge and Northfields section. Lots Road was permanently closed on 31 October 2003, being also replaced by power supply from the National Grid Network. Emergency lighting, powered by batteries, is available at every station, with emergency supply from a support power station in [[Greenwich]].{{sfn|Horne|2007|p=127}}