The Four Lines Modernisation (4LM) is a series of projects by

Transport for London Transport for London (TfL) is a local government body responsible for most of the transport network in London, United Kingdom. TfL is the successor organization of the London Passenger Transport Board, which was established in 1933, and His ...

(TfL) to modernise and upgrade the sub-surface lines of the

London Underground The London Underground (also known simply as the Underground or as the Tube) is a rapid transit system serving Greater London and some parts of the adjacent home counties of Buckinghamshire, Essex and Hertfordshire in England. The Undergro ...

: the

Circle A circle is a shape consisting of all point (geometry), points in a plane (mathematics), plane that are at a given distance from a given point, the Centre (geometry), centre. The distance between any point of the circle and the centre is cal ...

District A district is a type of administrative division that in some countries is managed by the local government. Across the world, areas known as "districts" vary greatly in size, spanning regions or county, counties, several municipality, municip ...

, Hammersmith & City and Metropolitan lines. The upgrades entail new rolling stock, new automatic signalling and new track and drainage. New trains were delivered between 2010 and 2017, with automatic signalling completed on the Circle line in March 2022 and on the Hammersmith and City line in January 2023.

History

Following the implementation of the London Underground

Public Private Partnership In public relations and communication science, publics are groups of individual people, and the public (a.k.a. the general public) is the totality of such groupings. This is a different concept to the sociological concept of the ''Öffentlichke ...

(PPP) in 2003, the Metronet consortium became responsible for the infrastructure on the District, Circle, Hammersmith & City and Metropolitan lines. As part of the PPP, Metronet would deliver 190 new trains built by

Bombardier Transportation Bombardier Transportation was a Canadian rolling stock and rail transport manufacturer, with headquarters in Toronto and Berlin. It was one of the world's largest companies in the rail vehicle and equipment manufacturing and servicing industry. ...

and install new automatic signalling from

Westinghouse Rail Systems Westinghouse Rail Systems Ltd (formerly ''Westinghouse Signals Ltd'') was a British supplier of railway signalling and control equipment to the rail industry worldwide. Its head office was in Chippenham, Wiltshire, where it manufactured a varie ...

. The first train was planned to enter service on the Metropolitan line by 2009, with all trains in service by 2015. 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. 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. This work would be completed by 2018. However the contract was terminated by TfL in 2014 due to delays, cost overruns and the complexity of the task. The decision by TfL to pay Bombardier £80m to end the contract was subsequently criticised by the

London Assembly The London Assembly is a 25-member elected body, part of the Greater London Authority, that scrutinises the activities of the Mayor of London and has the power, with a two-thirds supermajority, to amend the Mayor's annual budget and to reject t ...

. In 2015, the contract was awarded to

Thales Thales of Miletus ( ; ; ) was an Ancient Greek philosophy, Ancient Greek Pre-Socratic philosophy, pre-Socratic Philosophy, philosopher from Miletus in Ionia, Asia Minor. Thales was one of the Seven Sages of Greece, Seven Sages, founding figure ...

, with the replacement of signalling now costing £760m. It would also be delivered four years later than originally planned, in 2023.

Rolling stock

As part of the upgrade, the entire sub-surface fleet was to be replaced. S7 and S8 Stock manufactured by

Derby Litchurch Lane Works Derby Litchurch Lane Works, formerly Derby Carriage and Wagon Works, is a railway rolling stock factory in Derby, England. It is presently owned by the multinational transportation manufacturer Alstom. Derby works originally commenced productio ...

were ordered to replace the A60/62 Stock on the

Metropolitan line The Metropolitan line, colloquially known as the Met, is a London Underground line between in the City of London and and in Buckinghamshire, with branches to in Hertfordshire and in London Borough of Hillingdon, Hillingdon. Printed in mage ...

, the C69/77 Stock on the

(Edgware Road to Wimbledon section) and Hammersmith & City lines, and the D78 Stock on the rest of the

District line The District line is a London Underground line running from in the east and Edgware Road tube station (Circle, District and Hammersmith & City lines), Edgware Road in the west to in west London, where it splits into multiple branches. One br ...

, all of which dated from the 1950's, 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 are the train lengths and seating arrangements, where the S7 Stock consists of seven cars in a longitudinal-only layout and the S8 Stock has eight cars with a mixture of longitudinal and transverse seating. New features that were not used on the previous rolling stocks include air-conditioning, low floors to ease accessibility, and open gangways between carriages. The entire fleet was introduced by April 2017.

Signalling

Part of the modernisation includes the introduction of

communications-based train control Communications-based train control (CBTC) is a railway signaling system that uses telecommunications between the train and track equipment for traffic management and infrastructure control. CBTC allows a train's position to be known more accura ...

(CBTC) to allow for

automatic train operation Automatic train operation (ATO) is a method of operating trains automatically where the driver is not required or is required for supervision at most. Alternatively, ATO can be defined as a subsystem within the automatic train control, which pe ...

(ATO) via

SelTrac SelTrac is a digital railway signalling technology used to automatically control the movements of rail vehicles. It was the first fully automatic moving-block signalling system to be commercially implemented. SelTrac was originally developed ...

system. The grade of automation is GoA2, similar to other lines on the London Underground. In order to upgrade the signalling, Signal Migration Areas have been created to allow for the gradual installation. Below is a list of the SMAs and their progress: As a result of 5 being installed, the

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 National Rail (NR) is the trading name licensed for use by the Rail Delivery Group, a group representing passenger train operating companies (TOCs) of England, Scotland, and Wales. The TOCs run the passenger services previously provided by ...

& the

Piccadilly line The Piccadilly line is a Deep level underground, deep-level London Underground line running between the west and the north of London. It has two western branches which split at Acton Town tube station, Acton Town and serves 53 stations. The li ...

, SMAs 10-12 were scaled back until further notice. Originally the were planned as follows:

Notes

References

External links

* {{Official website London Underground