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LogoPiccadilly Line

A Yerkes Tube

[last modified 2014-08-01]

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History
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Dates
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Features
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Services
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Topology
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Layout
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Depots
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Connections
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Rolling stock

History

The original Piccadilly Line - from Finsbury Park to Hammersmith - was formed by merging three separate proposals. From east to west, these were:

The District purchased the B&PCR in 1898. In 1901 the Yerkes Group took over all three companies before any construction had been started and combined the three proposals into the Great Northern, Piccadilly & Brompton Railway (though in day-to-day use this was quickly abbreviated to the Piccadilly Railway or the Piccadilly Tube). The B&PCR route had already been altered by the District at the west end so as to meet the DLD at South Kensington (with a sharp curve), and was now altered at the east end to meet the GN&SR at Holborn. The planned DLD route was extended in the west to emerge at Barons Court and was abandoned east of South Kensington once it became clear that the Piccadilly combined with an electrified District could handle the traffic. The junction in the eastbound tunnel is still visible at the end of the platform; there was also a separate westbound DLD platform, but this seems to have disappeared during a recent reconstruction of the station.

At the eastern end of the line, the GNR considered the territory beyond Finsbury Park their own. Therefore when they agreed to hand over the route to Yerkes, they retained ownership of the tube station (under their main-line one) and demanded a veto over any extension northwards. Thus Finsbury Park became the terminus of the line and, despite increasing congestion of road traffic, the GNR and their successor the LNER refused consent for any extension for many years (they also did the same to the Great Northern & City Railway, described under the Northern Line). Eventually public opinion became strong enough to force the matter, and in the 1930s the line was rapidly extended into the suburbs.

Also in the 1930s, the District Line was suffering congestion on its city section, which was being fed from the west by no less than 5 branches plus the Circle. Therefore the Piccadilly was extended over two of these (to Hounslow and to Uxbridge), giving a second outlet for the traffic. The original layout between the tube mouths (at Barons Court) and Hammersmith had the Piccadilly tracks on the north side of the District; both this section and the tracks westwards to Acton Town were now rearranged, with the Piccadilly Line running between the District tracks. West of Acton Town, both lines continued to serve the Hounslow branch (until 1964), but the Rayners Lane branch was totally taken over. The District service was withdrawn in two stages, firstly to South Harrow and later - after the formation of London Transport - the rest of the way to Uxbridge (the original powers to run beyond South Harrow applied explicitly to the MDR, and the Yerkes group were unwilling to take the legal risk of running any other trains that way).

During World War II, the closed station at Down Street was converted into the headquarters of the Railway Executive - the body that controlled all railways during and immediately after the war. Walls were built along the platform edges, and the resulting space was converted to offices. Access was normally from the surface, but trains could also be stopped to allow people in and out of the driver's cab. Brompton Road was also converted and used for London Anti-Aircraft Control; later it was a Territorial Army training centre and may have been used by the Auxiliary Fire Service.

In the 1970s the Hounslow branch was extended to Heathrow Airport, which at the time consisted of three terminals grouped around a central point. In the 1980s a fourth terminal was added on the south side of the airport and the line was extended in a loop to serve it; the loop was made longer than strictly necessary so as to serve the planned location of the fifth terminal. However Terminal 5 was eventually built much further west and, therefore, the original route was extended directly to it while leaving the loop in place to serve Terminal 4. Because of unstable ground, it was not possible to construct the junction between the loop and the extension while trains were running and so the loop was closed for the duration of the works.

The Aldwych branch

The erstwhile Aldwych branch has always been a curiosity. It was left over from the GN&SR route when the Piccadilly to Holborn section was added, and it remains unclear why it was ever built. Although the GN&SR powers to build north of Finsbury Park were formally abandoned, the same didn't happen here. It is possible that attempts were made but Parliament rejected them; if so, no record has been left. The original plan was to terminate north of the Aldwych, but in 1902 the proposed route was extended to Temple station on the District Line, then amended to run to Waterloo instead. Powers were only ever granted for the section actually built.

The branch is located directly under the Kingsway and its tram subway, which were being constructed at about the same time as the Piccadilly. Tunnelling for the branch had to wait until they were finished, and it opened after the rest of the line. Before construction even started the Yerkes group applied to have it extended to Temple, but they were only allowed to go as far as the south side of the Strand.

Further adding to the mystery is the strange track layout. Though the branch was constructed as double track, it was done in a way that meant it could not be integrated with the rest of the line. The original design had the southbound track diverging from the main line west of Holborn station (with a single southbound platform for both routes) while the northbound tracks each had their own platform, converging east of the station. But as built, the "southbound" track (that is, the eastern of the two south of Holborn) connected to the northbound at Holborn, while the western track terminated in a separate bay between the two through northbound platforms. Furthermore, the two tracks were connected by only a single crossover just south of Holborn and the western track had no signals, being operated on the "one train" principle. The platforms at both stations were also much shorter than those on the rest of the line.

With this layout the only sensible thing to do was to operate the branch as a shuttle between Holborn and Aldwych (during peak hours until 1912 there was one shuttle on each track) and this is how it operated for its entire life; the only exceptions were a few Aldwych to Finsbury Park trains (eastbound only) to serve theatre-goers, withdrawn in 1908. In 1917 the line was singled, using the western of the original tracks for most of its length but the crossover and the eastern one at Holborn.

A number of plans were made to extend the branch to Waterloo, but none came to fruition; it would also have been saved had the Jubilee Line been extended via Fleet Street as originally planned, rather than via Waterloo. The branch was closed during World War II (the eastern tunnel was used to hold valuables from the British Museum and the western as an air-raid shelter, both with the tracks removed or boarded over). From then on all was downhill: after 1958-06-07 trains ran only in the weekday peak hours, apart from a 07:00 to 14:00 Saturday service which survived until 1962-06-16. Final closure came in 1994 as a way to avoid the cost of replacing the lifts at Aldwych.

After being taken out of use by the 1917 modifications, the eastern platform at Aldwych was used for design work, as well as appearing (under many names) in various films, while the bay at Holborn was apparently converted into university accommodation and then laboratories; currently part is a canteen while another part holds an electricity substation.

Dates

The lines from Hounslow West and Uxbridge to Barons Court have a long history before the Piccadilly reached them or took them over. This history is covered on the District and Metropolitan Line pages and is not duplicated here.

Chiswick Park, Stamford Brook, and Ravenscourt Park stations have never been served by the Piccadilly Line in normal service and so they are not counted as stations for the purposes of this section.

key to symbols

1906-12-15 Hammersmith (2) to Barons Court started [Piccadilly]
[15] Barons Court to Finsbury Park opened
1907-01-08 + South Kensington
1907-03-15 + Down Street
1907-04-11 + Covent Garden
1907-11-30 0 Aldwych to Holborn opened
1908-10-03 Through trains from Aldwych to Finsbury Park withdrawn
1926-05-04 - Brompton Road (General Strike)
1926-10-04 + Brompton Road
1932-05-21 - Down Street
1932-07-04 South Harrow to Hammersmith (2) started [Piccadilly]
-= Turnham Green[1]
1932-09-17 - York Road
1932-09-19 4 Finsbury Park to Arnos Grove opened
1933-01-09 Northfields to Acton Town started [Piccadilly]
-= South Ealing
1933-03-13 Hounslow West to Northfields started [Piccadilly]
1933-03-13 1 Arnos Grove to Oakwood opened
1933-07-31 0 Oakwood to Cockfosters opened
1933-10-23 Uxbridge to South Harrow started [Piccadilly]
1934-03-25 = Osterley
1934-07-29 - Brompton Road
1935-04-29 + South Ealing [Piccadilly]
1935-07-05 = South Harrow
1938-12-04 < Uxbridge
1939-08-31 - Knightsbridge, Hyde Park Corner, Green Park, King's Cross St. Pancras, Arsenal
1939-11-17 + King's Cross St. Pancras
1939-12-01 + Knightsbridge, Green Park, Arsenal
1939-12-08 + Hyde Park Corner
1940-09-21 Aldwych to Holborn closed
1940-10-13 Wood Green to Cockfosters closed (bomb at Bounds Green)
1940-10-14 King's Cross St. Pancras to Wood Green closed (bomb at Holloway Road)
1940-12-05 [6] King's Cross St. Pancras to Wood Green reopened
X York Road
1940-12-09 2 Arnos Grove to Cockfosters reopened
1940-12-16 1 Wood Green to Arnos Grove reopened
1944-03-02 South Harrow to Ealing Common closed (bomb near Alperton)
Ealing Common to Acton Town withdrawn (in consequence)
1944-03-07 5 South Harrow to Ealing Common reopened
Ealing Common to Acton Town restored
1946-07-01 0 Aldwych to Holborn reopened
1963-06-23 + Turnham Green[1]
1975-07-14 < Hounslow West
1975-07-19 0 Hatton Cross to Hounslow West opened
1977-12-16 0 Heathrow Terminals 1, 2, 3 to Hatton Cross opened
1985-11-20 Passenger train erroneously sent around Heathrow Terminal 4 loop
1986-04-07 [0] Heathrow Terminal 4 loop opened
1986-04-12 + Heathrow Terminal 4
1987-08-30 - Gloucester Road (lift replacement)
1989-05-21 + Gloucester Road
1992-12-06 = Hillingdon
1994-09-30 Aldwych to Holborn closed
1996-09-28 -= Turnham Green[1]
1997-01-26 + Turnham Green[1]
1997-06-01 - Holborn (escalator problems)
1997-06-30 + Holborn
1997-11-22 - Earl's Court (escalator renewal)
1998-04-06 + Earl's Court
2000-09-15 - Knightsbridge (escalator problems)
2000-09-18 - King's Cross St. Pancras (escalator problems)
2000-10-10 + King's Cross St. Pancras
2000-10-11 + Knightsbridge
2001-11-23 - Earl's Court (escalator renewal)
2002-03-05 + Earl's Court
2002-11-22 - Gloucester Road, Covent Garden, Russell Square, Caledonian Road, Holloway Road (firefighters' strike)
2002-11-30 + Gloucester Road, Covent Garden, Russell Square, Caledonian Road, Holloway Road
2003-03-05 - Russell Square (lift problems)
2003-03-18 + Russell Square
2005-01-02 - Ruislip Manor, eastbound only (reconstruction)
2005-01-06 Heathrow Terminal 4 loop closed (Terminal 5 works)
2005-04-27 - Sudbury Hill, Ealing Common, both eastbound only
2005-05-07 ?+ Sudbury Hill, Ealing Common, both eastbound only
2005-05-08 - Sudbury Hill, Ealing Common, both westbound only
2005-05-21 ?+ Sudbury Hill, Ealing Common, both westbound only
2005-07-07 Hyde Park Corner to Arnos Grove closed (bomb explosion on train between Russell Square and King's Cross St. Pancras)
Uxbridge to Rayners Lane withdrawn (in consequence)
- Ruislip Manor, westbound only (reconstruction)
2005-07-09 -= Ruislip Manor, eastbound only
2005-08-04 Uxbridge to Rayners Lane restored
+ Ruislip Manor, eastbound only
[15] Hyde Park Corner to Arnos Grove reopened
X Down Street, York Road
2005-12-22 + Ruislip Manor, westbound only
2006-07-22 - Arsenal
2006-08-07 ?+ Arsenal
2006-09-17 1 Heathrow Terminal 4 loop reopened
2006-10-01 - Arsenal (eastbound only)
2006-10-07 + Arsenal (eastbound only)
2006-10-08 - Arsenal (westbound only)
2006-10-14 + Arsenal (westbound only)
2007-02-17 - Arsenal
2007-03-03 + Arsenal
2008-03-27 0 Heathrow Terminal 5 to Heathrow Terminals 1, 2, 3 opened
2014-05-23 - Gloucester Road (lift replacement)
2014-07-18 Uxbridge to Rayners Lane closed (track replacement)[2]
2014-08-11 5 Uxbridge to Rayners Lane reopened
2014-12 + Gloucester Road

[1] Turnham Green has never been a regular stop for Piccadilly services. For those periods it is shown as open, trains stopped only in the early morning, late evening, and - at some periods - all day Sunday, presumably to improve connections to and from the District Line Richmond branch.

[2] During this closure, the last train to Rayners Lane on weekdays was extended to Ruislip, returning out of service.

Features

The central section, the Heathrow area from just west of Hatton Cross station, and a short section of track around Southgate station are in tube. From Hounslow West to Hatton Cross is a subsurface tunnel, though there is a small surface section between Hounslow West and Hatton Cross where the line crosses the River Crane. There is also a short tunnel west of Hammersmith station.

The line emerges from tube east of Barons Court, and the Piccadilly tracks run between the District tracks from the tube mouths to Acton Town. There are four tracks from Acton Town to Northfields: two "fast" and two "local". There is now no distinction between these, but for some years the eastbound local was used as a test track and was not in normal service.

The layout at Acton Town is complex:

        To Ealing Common (station and depot)
               EB WB Depot access
                \  \  \
                 \  \  \
                  \  \  \      [--------------\
                   \  \  \                     \
                    \  \  \---------------\     \---*-----*-----------
    Eastbound local  \  \                  \       / ##### \    EB Dist.
    -------------]    \  \--------------*---*-----*  #####  \
    Eastbound fast     \               /           \ #####   \  EB Picc.
    ------------------] \ [---------*-*-------------*---------*-------
    Westbound fast       \     ----*
    --------------------] \ [-------*--------------*----------*-------
    Westbound local        \                      /  #####   /  WB Picc.
    ------------------\     \--*-----------------/   #####  /
                       \        \                    ##### /    WB Dist.
                        \--------*------------------------*-----------

[sidings at the east end of the station omitted]

At Northfields the westbound track dives under Northfields depot access track, after which the line is double track again to Hatton Cross.

The route to Heathrow Terminal 5 is double track, while the Terminal 4 loop is single track with trains running in the clockwise (decreasing kilometrage) direction only. The loop connects only to the westbound at Hatton Cross, while at the Terminals 1,2,3 end it connects to both tracks (though, of course, only the eastbound is normally used). The tube section of the Terminal 4 loop was all built with a diameter of 3.81m (12'6"). The first section of tunnel after it diverges from the main route at Hatton Cross is, unusually, "tube-and-cover" - a large hole was dug into which a prefabricated tube was placed; the hole was then filled in.

The Holborn to Aldwych section was single track, connecting only to the eastbound line at Holborn. The track remains, though unused.

Though the line is described as east/westbound throughout, the section from Cockfosters to Holborn was formerly known as north/southbound, and evidence of this remains in old signs and the platform numbering.

Services

At the eastern end, most trains terminate at Cockfosters and a few at Arnos Grove; some also enter or leave service at Oakwood. At the western end, the situation is more complex. Heathrow gets a service of 12tph throughout the day, running alternately to Terminal 5 and round the Terminal 4 loop. At Terminal 5, trains reverse (empty) in the sidings and then stand for up to 7 minutes in the eastbound platform; trains running round the loop stand at Terminal 4 for 8 minutes so as to slot correctly into the service. (From 1986 to early 2005 and then late 2006 to early 2008, all trains except a few at the start and end of service ran around the loop and the westbound track from Hatton Cross was mostly unused.) In the peaks, the Uxbridge branch also sees 12tph, splitting 2:1 between Uxbridge and Rayners Lane as their terminus; previous timetables also used Ruislip as a third peak terminus with the service splitting equally between the three. Off-peak on weekdays the service is 9tph, while at weekends it is 12tph. At the start and end of service, and for the first hour or two at weekends, trains on the Uxbridge branch terminate at Acton Town, requiring a change to reach stations further east. One early morning train reverses at Wood Green, and on Sundays one early westbound train starts at Hyde Park Corner (where there is a reversing siding).

Until 1991-10-27, a few eastbound trains at the start and end of service hours terminated in the eastbound platform at West Kensington, running from and to Barons Court via the District tracks. Similarly, some trains at start and end of service have run via the District tracks between Hammersmith and Acton Town; this appears to have stopped in the mid-1990s. In emergencies Piccadilly Line trains have been used to provide a District Line service between Acton Town and Ealing Broadway.

It is claimed that on Sunday mornings in the mid-1990s a few early trains ran fast from Hatton Cross to Acton Town, stopping only at Northfields.

Minimum running times from Cockfosters are 94 minutes to Uxbridge, 83 minutes to Heathrow Terminal 4, and 88 minutes to Heathrow Terminal 5; in the other direction they are 97, 91, and 89 minutes respectively. It takes about 12 minutes to run from Hatton Cross round the Terminal 4 loop and back to Hatton Cross but, as described above, nearly all trains have an extended stop at Terminal 4.

Special services

During disruption on the District Line, Piccadilly Line trains have sometimes been used to provide a service to Ealing Broadway, either by diverting some trains bound for Rayners Lane and Uxbridge, or as a shuttle from Acton Town. Trains may also run along the District Line tracks from Hammersmith to Acton Town in order to serve those stations with no platforms on the Piccadilly Line.

Topology

        U---------R--1         <= West    East =>
                   \
                    \
                     \
                   2--L
                       \
     c--*-a---X----N====T~~~~~~~B-------H---------------C
       /     /                         /
       |    /                         A
       \-b-/

= = quadruple track
~ = double track between District tracks
A = Aldwych
B = Barons Court
C = Cockfosters
H = Holborn
L = Hanger Lane Junction
N = Northfields
R = Rayners Lane Junction
T = Acton Town
U = Uxbridge
X = Hatton Cross
a = Heathrow Terminals 1, 2, 3
b = Heathrow Terminal 4
c = Heathrow Terminal 5
1 = Metropolitan Line to Harrow-on-the-Hill
2 = District Line to Ealing Broadway

Layout

key to notation

Locations are listed down the page in the eastbound direction.

69.7 [-] [End of reversing sidings]
050758 69.40 [= ^=^W=E] !%[Z6] Heathrow Terminal 5
063759 67.58 [-] [PiccEx junction]
075758 67.17 [B=B] !%[Z6] Heathrow Terminals 1, 2, 3
65.08 [-] [Terminal 4 loop junction]
096753 64.99 [IP] [Z5/6] Hatton Cross
103757 64.20 [-] [River Crane crossing west portal]
107760 63.60 [-] [River Crane crossing east portal]
122761 62.08 [IP] [Z5] Hounslow West
62.04 [-] [tunnel mouths]
136759 60.64 [IP] [Z4] Hounslow Central
142762 59.90 [OP] ![Z4] Hounslow East
145771 58.93 [OP] [Z4] Osterley
58.63 [OP] ((Osterley & Spring Grove))
163787 56.50 [OP] [Z4] Boston Manor
171792 55.59 [W=WE=E] [Z3] Northfields
175793 55.11 [W=WE=E X] [Z3] South Ealing
194795 52.91 [W=WE=E] [Z3] Acton Town
203787 51.72 [=wWEe=] [Z3] {Chiswick Park}
207788 51.25 [-] [Turnham Green Junction (eastbound)]
212788 50.83 [-] [Turnham Green Junction (westbound)]
213788 50.71 [w=WE=e] [Z2/3] Turnham Green
218788 50.18 [w=WEe=] [Z2] {Stamford Brook}
225787 49.44 [w=WE=e] [Z2] {Ravenscourt Park}
231787 48.84 [-] [Studland Road Junction]
48.81 [-] [tunnel west portal]
48.57 [-] [tunnel east portal]
234785 48.51 [w=WE=e] ![Z2] Hammersmith (2)
241783 47!84 [w=WE=e] [Z2] Barons Court
47.41 [-] [tube mouths]
255785 46.22 [CPX4] !%[Z1/2] Earl's Court
262788 45.42 [CP3] ![Z1] Gloucester Road
268788 44.72 [=W =E +2] %[Z1] South Kensington
271790 44.2 [CP] (Brompton Road)
278796 43.49 [CPX] %[Z1] Knightsbridge
282798 42.97 [CPX] %[Z1] Hyde Park Corner
286800 42.48 [CP] (Down Street)
289802 41.91 [CP] %[Z1] Green Park
296806 41.37 [CPX2] %[Z1] Piccadilly Circus
299808 40.84 [CP] %[Z1] Leicester Square
302810 40.58 [CP] ![Z1] Covent Garden
305815 40.01 [=3Wb5==4E] %[Z1] Holborn
39.89 [-] [Aldwych branch junction]
301821 39.26 [OP] ![Z1] Russell Square
38.42 [-] [King's Cross Loop Junction]
302829 38.34 [CPX4] %[Z1] King's Cross St. Pancras
37.7 [CP] (York Road)
305849 36.38 [CP] ![Z2] Caledonian Road
309854 35.78 [CP] ![Z2] Holloway Road
314861 35.04 [CP] [Z2] Arsenal
313867 34.34 [s==W n==E] [Z2] Finsbury Park
320874 33.30 [CP] %[Z2/3] Manor House
315896 30.98 [CP#] %[Z3] Turnpike Lane
310904 29.99 [CP] %[Z3] Wood Green
300915 28.46 [CP] %[Z3/4] Bounds Green
294918 27.80 [-] [tube mouths]
293925 27.21 [W=2B3=E] [Z4] Arnos Grove
292937 25.91 [-] [tube mouths]
296942 25.26 [CP] %[Z4] Southgate
298944 25.06 [-] [tube mouths]
293959 23.39 [IPX] [Z5] Oakwood
281963 22.04 [V=2V3=V] [Z5] Cockfosters

096753 73=36 [IP] [Z5/6] Hatton Cross
73.27 [-] [Terminal 4 loop junction]
080745 71.53 [=W] [Z6] Heathrow Terminal 4
67.79 [-] [end of single line section]
063759 67.58 [-] [PiccEx junction]
075758 67.17 [B=B] !%[Z6] Heathrow Terminals 1, 2, 3

055841 73.03 [T1=2T2=3T] [Z6] Uxbridge
075850 70.93 [OP] ![Z6] Hillingdon
70.86 [OP] ((Hillingdon Swakeleys))
081858 69.85 [OP] [Z6] Ickenham
086864 69.11 [-] [Ruislip siding entrance]
095869 68.00 [OP] [Z6] Ruislip
101872 67.28 [OP] [Z6] Ruislip Manor
112876 66.14 [OP] [Z5] Eastcote
129875 64.41 [OP] [Z5] Rayners Lane
131874 64.33 [-] [Rayners Lane Junction]
143863 62.57 [OP] [Z5] South Harrow
144862 62.40 [OP] ((South Harrow))
148857 [-] [Proposed junction with GCR]
154855 61.15 [OP] [Z4] Sudbury Hill
168848 59.50 [OP#] [Z4] Sudbury Town
180837 57.93 [OP] [Z4] Alperton
187828 [OP] ((Park Royal & Twyford Abbey))
191822 55.95 [OP] [Z3] Park Royal
189812 54.88 [OP] [Z3] North Ealing
188810 54.56 [-] [Hanger Lane Junction]
189803 53.94 [OP] [Z3] Ealing Common
194795 52.91 [W=WE=E] [Z3] Acton Town

308809 40.61 [= T=] (Aldwych)
40.2 [-] [former crossover]
305815 40.01 [=3sB5==4n] %[Z1] Holborn
39.89 [-] [Aldwych branch junction]

Depots

The line is served by two depots. Cockfosters Depot is on the west side of the line between Cockfosters and Oakwood stations, and can be entered from either end. Northfields Depot is on the south side of the line between Northfields and Boston Manor station; the main entry and exit is at the former, where trains can enter and leave without fouling the running lines, while there is a single track connection westwards just west of Boston Manor station.

Connections

The Piccadilly is the best connected of the tube lines. There are connections to the Victoria and Northern Lines, described under those lines. Between Barons Court and Hammersmith, District Line trains can transfer to the Piccadilly Line and vice versa. Finally, the line shares tracks with the District from Acton Town to Hanger Lane Junction, and with the Metropolitan from Rayners Lane Junction to Uxbridge, where there is a connection to Ruislip Depot and thence the Central Line.

Rolling Stock

The line is operated by 1973 Tube Stock, designed with some luggage space for airport travellers. The trains are made of two 3-car units; single units have only one cab and are restricted to depots. Trains are being refurbished, and unrefurbished and refurbished units may not be coupled together. The refurbished units contain an auxiliary static converter which can interfere with signalling equipment, and this must be isolated before the train can run on any line other than those specially immunized (the Piccadilly Line, the District Line from Gloucester Road to Ealing Common, and the Metropolitan Line from Harrow-on-the-Hill to Uxbridge).

1959 and 1972 Tube Stock may operate on any part of the line. The latter can only enter the sidings at Arnos Grove and platform 1 at Cockfosters as a single 4-car unit without passengers.

1967 Tube Stock (with tripcocks) may run empty. 8-car trains are forbidden to enter Cockfosters station, the sidings at Acton Town, Arnos Grove, Barons Court, Down Street, South Harrow, and Wood Green, or Northfields Depot (other than siding 7). Because of signalling problems only 4-car trains without passengers may run west of Northfields or on the local westbound line from Acton Town.

Subsurface stock may run from the crossovers west of Barons Court to Northfields, and A and C stock may also run to Rayners Lane, though restricted to 15 mph when passing under three specific bridges:
- D4 (between South Harrow and Sudbury Hill)
- D24 (between Park Royal and North Ealing)
- D62 (Acton Town station westbound)
There are restricted clearances in certain parts of Northfields Depot. A stock may run in 4-car units only (and only double-ended units may carry passengers) east of Acton Town, on the westbound local line to Northfields, and in Northfields depot (other than siding 7) and the sidings at Acton Town, Barons Court, and South Harrow.

The Aldwych branch may only be used by 3-car double ended units of 1973 Tube Stock operating under an engineering possession.

Height detectors are mounted a short distance west of Barons Court on the eastbound track, and will prevent a subsurface stock train from being run into the Piccadilly platforms at the station or, more importantly, the tube section. These consist of U-shaped glass tubes silvered on the inside (previously they contained mercury) arranged so that an overheight train will smash them, breaking a circuit. Such tubes are also mounted between Hounslow Central and Hounslow West stations.


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