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Four Lines Modernisation

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The Four Lines Modernisation (4LM) is a series of projects by Transport for London (TfL) to modernise and upgrade the sub-surface lines of the London Underground: the Circle, District, Hammersmith & City and Metropolitan lines. The upgrades entail new rolling stock, new signalling and new track and drainage.[1][2]

History

Following the implementation of the London Underground Public Private Partnership (PPP) in 2003, the Metronet consortium became responsible for the infrastructure on the District, Circle, Hammersmith & City and Metropolitan lines.[3] As part of the PPP, Metronet would deliver 190 new trains built by Bombardier Transportation and install new automatic signalling from Westinghouse Rail Systems. The first train was planned to enter service on the Metropolitan line by 2009, with all trains in service by 2015.[3] All the trains would be built to the same design, saving on parts and maintenance costs for Metronet.

In July 2007, Metronet, the private consortium responsible for the infrastructure for the sub-surfaces lines, collapsed due to financial difficulties.[4] TfL subsequently took over the contract for the new trains, and organised a new contract for the replacement of signalling.

In 2011, a £350m contract was awarded to Bombardier to replace the signals on the four lines with their Cityflo 650 system.[5] This work would be completed by 2018.[5] However the contract was terminated by TfL in 2014 due to delays, cost overruns and the complexity of the task.[6][7] The decision by TfL to pay Bombardier £80m to end the contract was subsequently criticised by the London Assembly.[8]

In 2015, the contract was awarded to Thales, with the replacement of signalling now costing £760m.[6][9] It would also be delivered four years later than originally planned, in 2023.[6][10]

Rolling stock

Main article: London Underground S7 and S8 Stock
D78 Stock on its last day in service (right), next to its replacement, an S S7 Stock unit (left).

As part of the upgrade, the entire sub-surface fleet was to be replaced. S7 and S8 Stock manufactured by Bombardier Transportation's Derby Litchurch Lane Works were ordered to replace a variety of rolling stock, these being the A60/62 Stock on the Metropolitan line, the C69/77 Stock on the Circle, District (Edgware Road to Wimbledon section) and Hammersmith & City lines, and the D78 Stock on the District line, which all dated from the 1960s and 1970s.

The order was for a total of 192 trains (1,403 cars), and formed of two types, S7 Stock for the Circle, District and Hammersmith & City lines and S8 Stock for the Metropolitan line. The main differences, aside from the number of cars (S7 having seven cars and the S8 having eight cars), were in the seating arrangements, in which the S7 Stock consisted of a longitudinal-only layout, whereas the S8 Stock had a mixture of longitudinal and transverse seating. New features that were not used on the previous rolling stocks included air-conditioning, low floors to ease accessibility, and open gangways between carriages.[11][12]

The entire fleet was introduced by April 2017.

S Stock Introduction
Line Stock First Unit Introduced Fully Introduced
Circle S7 2 September 2013 11 February 2014
District S7 2 September 2013 21 April 2017
Hammersmith & City S7 6 July 2012 11 February 2014
Metropolitan S8 31 July 2010 26 September 2012

Signalling

Part of the modernisation includes the introduction of Communications-Based Train Control (CBTC) to allow for Automatic Train Operation (ATO) via Thales's SelTrac system.[13] In order to upgrade the signalling, Signal Migration Areas have been created to allow for the gradual installation.[14] Below is a list of the SMAs and their progress:

Signal Migration Areas
SMA From To Line(s) Status Date
0.5 Hammersmith Latimer Road Circle and Hammersmith & City Completed March 2019
1 Latimer Road Paddington Circle and Hammersmith & City Completed September 2019
2 Paddington & Finchley Road Euston Square Circle, District, Hammersmith & City and Metropolitan Completed September 2019
3 Euston Square Monument & Stepney Green Circle, District, Hammersmith & City and Metropolitan Completed March 2021
4 Monument Sloane Square Circle & District Completed April 2021
5 Sloane Square Barons Court, Fulham Broadway,

Olympia & Paddington

Circle and District Completed March 2022
6 Stepney Green Becontree District and Hammersmith & City Completed January 2023
7 Becontree Upminster District Completed March 2023
8 Finchley Road Preston Road Metropolitan Planned 2024+ (TBC)
9 Preston Road
  • West Harrow
  • Moor Park
 Metropolitan Planned 2024+ (TBC)
10* Barons Court
  • Stamford Brook
 District Deferred TBD
11* Stamford Brook Richmond & Ealing Broadway District Deferred Until further notice
12* Fulham Broadway East Putney District Deferred TBD
13 Moor Park
  • Watford
  • Amersham
  • Chesham
 Metropolitan Planned 2025+ (TBC)
14 West Harrow Uxbridge Metropolitan Planned 2025+ (TBC)

As a result of SMA 5 being installed, the Circle line began running entirely under ATO and after the completion of SMA 6 the Hammersmith & City line also now runs completely under ATO.


For various reasons including funding and the technical difficulties with sharing tracks with National Rail & the Piccadilly line, SMAs 10-12 were scaled back until further notice.

Originally the SMAs were planned as follows:[14]

Signal Migration Areas
SMA From To Line(s)
10 Barons Court Richmond & Chiswick Park District
11 Chiswick Park Ealing Broadway District
12 Fulham Broadway Wimbledon District

References

  1. ^ "Four Lines Modernisation". Transport for London. Retrieved 2022-05-11.
  2. ^ "THIRD TIME LUCKY FOR SUB-SURFACE RESIGNALLING". www.modernrailways.com. 1 December 2022. Retrieved 2023-04-30.
  3. ^ a b "Metronet Brochure 2005" (PDF). Metronet (British infrastructure company). 2005. Archived from the original (PDF) on 31 October 2006. Retrieved 7 March 2021.
  4. ^ "Metronet calls in administrators". BBC News. 18 July 2007. Retrieved 7 March 2021.
  5. ^ a b "Bombardier wins major Underground signalling project". Rail News. 15 June 2011. Retrieved 2023-04-30.
  6. ^ a b c "Plans to modernise four London Underground lines 'double' in cost". BBC News. 2015-08-03. Retrieved 2023-04-30.
  7. ^ "Bombardier loses sub-surface lines signalling contract". www.railtechnologymagazine.com. 2 January 2014. Retrieved 2023-04-30.
  8. ^ "Transport for London criticised over £80m payout". BBC News. 2014-10-23. Retrieved 2023-04-30.
  9. ^ "Thales wins one billion euro contract to upgrade London underground lines". Reuters. 2015-08-03. Retrieved 2023-04-30.
  10. ^ "THIRD TIME LUCKY FOR SUB-SURFACE RESIGNALLING". www.modernrailways.com. 1 December 2022. Retrieved 2023-04-30.
  11. ^ "SQUAREWHEELS.org.uk – S stock". www.squarewheels.org.uk. Retrieved 2022-05-11.
  12. ^ "S7/8 stock - Tube History". tube-history.uk. Retrieved 2022-05-11.
  13. ^ Kessell, Clive. "Progress with the Four Lines Modernisation project". RailEngineer. Retrieved 10 January 2024.
  14. ^ a b "Programmes and Investment Committee - Four Lines Modernisation Update" (PDF). Transport for London. 13 October 2017. Retrieved 24 July 2022.
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