Northern Line Extension (NLE)

New stations open to passengers

On Monday, September 20, 2021, the Northern line extension (NLE) between Kennington and Battersea opened to the public. The new extension, which is the first significant Tube extension this century, is already helping to revitalise the Vauxhall, Nine Elms, and Battersea boroughs.

The Northern Line Extension (NLE), which includes 3 kilometres of new tunnels and new stations at Nine Elms and Battersea Power Station, is now fully operational, linking passengers to the Northern Line’s Charing Cross branch at Kennington. The opening marks the end of a six-year building project led by Ferrovial and Laing O’Rourke, which collaborated under the name Flo to plan and build the new link for Transport for London (TfL).

Two Tunnel Boring Machines Launched

FLO employed two 304-tonne tunnel boring machines, named Helen and Amy to excavate and line the tunnels, as well as more than 20,000 precast concrete tunnel lining segments.The utilisation of these tunnel boring machines has been critical to the project’s success. The NLE took a big stride forward in 2017 when tunnelling work to expand the line to Battersea commenced. The two massive tunnel boring machines were dropped 20 metres below the earth in Battersea in February. Helen started her 3.2-kilometre tunnelling expedition in April, while Amy started in May.

The project’s tunnelling went well, including the contraction of the cross-plate junction where the new and old tunnels converge. The construction of the connection was accomplished by drilling a larger diameter tunnel around the existing tunnel while the existing tunnel was in operation- All of the tunnels were dug out of London Clay.

Over 850,000 tonnes of excavated soilwas delivered by river barge from Battersea which was deposited near Tilbury, where it was turned into agricultural land. The river helped to keep 47,000 vehicle movements off the roads and 2,600 tonnes of CO2 out of the atmosphere.

Revolutionary Modular Cable Route Management System (CRMS)

TransforgeUK Ltd was personally involved with the Northern Line Extension’s Cable Route Management System within the new tunnels, offering three different bracket design concepts. The CRMS’s design is groundbreakingas it has never been employed in a TFL tunnel before.The CRMS was welcomed as a bespoke modular system consisting of three separate curved backplates – 13-way, 7 way, and 11 way – to provide support for signalling, communication, HV and LV power and earth cables onto brackets that effectively clipinto the backplate so the system is sustainable and future-proof.

TransforgeUK Ltd created designs for cable capacities and loading capabilities (dead/wind and accidental) that included an innovative element – a one-of-a-kind locking mechanism. Once installed, this keeps the bracket from becoming dislodged as a result of wind pressures created by passing trains.

Fit-Out and Completion

The construction and interior fit-out work necessitated extensive coordination across several work packages, trades, and subcontractors. High-voltage and low-voltage electrical subsystems, tunnel ventilation, mechanical ventilation, and the building control system, fire prevention and control, communications equipment, lifts and escalators, pumping systems and drains, and the integration of the subsystems, as well as other TfL subsystems such as signalling and ticketing, were among the mechanical and electrical works.

With 79 apprentices and 159 formerly jobless individuals working, the initiative has been a source of strength in London and beyond. The team also worked with the local community, including 115 workshops with local schools, reaching over 3,000 youngsters, and contributing 1,629 days of work experience.

Transforge (UK) Ltd

Discover the comprehensive manufacturing component solutions for the tunnel boring industry.

Transforge (UK) Ltdhas become an established manufacturer of bored tunnel components for civil, mechanical and electrical engineers throughout the whole tunnel excavation and underground infrastructure tunnelling and fit-out process.

We’ve designed and manufactured a range of equipment and components for tunnelling projects including:

  • Utility cable and pipe supports
  • Slurry pipe brackets and accessories
  • Ventilation supports
  • Emergency walkway systems and platforms
  • Track, Sleepers and accessories
  • Shaft Steelwork
  • Structural steelwork to BSEN1090 EXC 3. (Execution Class 3)


If you would like to get in touch about a tunnelling project or tunnelling components, please do not hesitate to contact us.

Tel: +44 (0)1733 249260

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