Лондонская линия Overground: от Уотерфорда до Юстона

London Overground line

The Watford DC line is a suburban line from London Euston to Watford Junction in Watford, Hertfordshire. Its services are operated by London Overground. In February 2024 TfL announced a re branding as the Lioness line. The line runs beside the West Coast Main Line (WCML) for most of its length. The London Underground Bakerloo line shares the section of the line from Queen's Park to Harrow & Wealdstone. The rolling stock used on the line are Class 710 "Aventras" made by Bombardier. The "DC" in the title refers to line being electrified using direct current. This was done in the early twentieth century with conductor rails to be compatible with the four rail system used by the Underground and, at the time, the North London Line; currently, the line uses a third rail system, with a fourth rail available on the section shared with the Bakerloo line. By contrast, the WCML uses overhead alternating current.

Services on this line began when London and North Western Railway (LNWR) completed the Camden to Watford Junction new line in 1912, to provide additional suburban capacity and more outer suburban services running non stop to Euston. It incorporated part of the LNWR Rickmansworth branch (formerly the Watford and Rickmansworth Railway) between Watford Junction and Watford High Street Junction and part of the original slow main line between Queen's Park and South Hampstead stations; two single track tunnels take the line from South Hampstead to Camden, whence the line reaches Euston station by the main line tracks. Prior to 1912, at which time the entire route was finally electrified, services were steam operated. Although the operation of the line is mostly self contained, connections at Watford Junction and Camden allow other trains onto it, a facility used occasionally with trains diverted from the West Coast Main Line should an alternative diversionary route be not available.

The original electrification was on a fourth rail system, similar to that now used by London Underground, which allowed LER trains to use the new line. Power was supplied from the railway's own power station at Stonebridge Park until the 1960s when it was closed, after which it has been obtained from public supplies. As originally installed, there was provision for interconnection of the high voltage section of the power station to adjacent public supplies for output or intake but this ceased when national supplies were standardised at 50 Hz. In the late 1950s, the original electric multiple units built for the line were replaced by new Class 501 rolling stock. These were in turn displaced in the mid 1980s by Class 313 units. The line is now operated by London Overground Class 710 "Aventra" units. In the 1970s, the track and the rolling stock used on this line and the North London Line were changed to use a modified version of the BR standard third rail system, with the fourth rail (now bonded to the running rail used for returning traction current) left in place on the sections of line shared with LU Bakerloo line trains. North of Harrow & Wealdstone, now the limit of LU operation, the fourth rail has in most places been dropped onto the sleepers and remains bonded, thus leaving the resistance of the current return path unaltered. The fourth rail remains in the normal position from Queens Park to Kilburn High Road up platform, where a trailing crossover between those two stations is maintained in use to allow reversal of Bakerloo line trains unable to gain access to London Underground at Queens Park, due to planned work or other reasons. The line is currently electrified (like all shared lines) using the standard compromise voltage of 660 V DC. This falls comfortably within the lower permanent voltage limit for the "Capitalstar" stock (500 V) and the upper permanent voltage limit for the 1972 tube stock (760 V). The line has now been converted to 750 V DC for the new "Aventra". A consequence of converting to third rail with the fourth rail provided only for LU use was that both planned and emergency use of the line by other 3rd rail capable trains was possible. Ignoring recent use of Class 508 trains, this last took place when Class 416 trains were diverted to Willesden Junction Low Level station when part of the North London Line was closed for a number of weeks in the late 1980s. The electricity grid Willesden substation in Acton Lane, Park Royal supplies 11 kV, three phase power to ten substations on the line, located at Camden, South Hampstead, Queens Park, Willesden, Harlesden, Wembley, Kenton, Harrow, Hatch End, Bushey and Watford.

The construction of a curve to link Rickmansworth (Church Street) to the Euston main line was planned. A new line would have then run south to Wembley, then passed under the main line and run on the east side to Euston, terminating in a loop. The loop was dropped on grounds of cost and, instead, services terminated at Euston main platforms or ran on the North London Railway to Broad Street. Pressure from local groups led to the building of a curve near Bushey, diverting the main route for new services over the existing branch line north to Watford Junction instead of south to Rickmansworth. In 1917 LER Bakerloo line services were extended over the new line from Queen's Park station to Watford Junction.

Bakerloo line services were cut back in stages and ceased north of Stonebridge Park station in 1982; in 1984 they were restored as far as Harrow and Wealdstone. The Croxley Green branch fell into disuse in the 1990s, and is now derelict. In the early 2000s the county council proposed to divert the Metropolitan line over the branch and on to Watford Junction (for more information see Croxley Rail Link).

The line was operated by British Rail (from 1986 as Network SouthEast) until privatisation. In the Network SouthEast period, it was briefly rebranded as the Harlequin line, after the stations of Harlesden and Queen's Park. From March 1997 until November 2007, the line was operated by Silverlink. In November 2007 Transport for London (TfL) took full management control of all the intermediate Watford DC line stations as part of the London Overground (LO) service with staffing during opening hours, automatic ticket gates and planned station refurbishment to the standard of the Tube network.

Another proposal to bring London Underground service to Watford Junction was the Croxley Rail Link, which envisaged diverting the Watford branch of the Metropolitan line along a re opened stretch of track to the west of Watford, effectively reinstating the former Croxley Green to Watford Junction service. Underground trains would then join the DC line at Watford High Street, potentially forming an interchange either with London Overground or the Bakerloo line, depending on the outcome of other projects. Funding for this project was agreed during November 2015, however after cost overruns and disagreements over funding sources, work on the project stopped in 2017, and it was confirmed in 2018 that the project would not be going ahead in its current form.

In July 2023 TFL announced that it would be giving each of the six rail lines, including the Watford to Euston route, new names by the end of 2024. In February 2024, it was confirmed that the Watford DC line would be named the Lioness line (to honour the England women's national football team who became European champions at Wembley Stadium in 2022) and would be coloured yellow on the updated network map.