First bore completed for Silvertown Tunnel

TBM Jill finished the 1.1km southbound drive from Newham on February 15, reaching the rotation chamber in Greenwich.

The TBM will now be rotated in pieces within the 40m rotation chamber, before starting its journey back under the River Thames to the Silvertown site in Newham, creating the second tunnel.

The rotation process will involve sections of the TBM being placed on ‘nitrogen skates’ in the chamber. The individual sections of the TBM, including the 1,200T cutterhead, will be spun 180 degrees inside the shaft before being reassembled and reconfigured.

It is expected the second bore will be completed by the end of the summer.

The 82m-long Herrenknecht TBM is the largest ever used in the UK, with a cutterhead diameter of 11.91m. Launched in September last year, it made an average advance of 18m a day.

Last year, less than three weeks after the TBM launch, tunnelling was halted for several weeks after fire damaged half of the conveyor belt.

Riverlinx CJV project director Juan Angel Martinez said the solutions being implemented on the project were pioneering for the UK market. “We continue to be committed to completing the project expertly in the most efficient, sustainable way and to the highest level of safety and quality,” he said.

At the two tunnel portals, piling and concrete pours for the foundations for the cut and cover sections of the tunnel, as well as the portal entrances, are under way.

Once open in 2025, the twin-bore Silvertown Tunnel will link Newham to the Greenwich Peninsula, easing congestion at the Blackwall Tunnel.

The project is being delivered by the Riverlinx CJV, a joint venture contracted by Transport for London (TfL) and Riverlinx comprising BAM Nuttall, Ferrovial Construction and SK ecoplant. The project is being delivered through a design, build, finance, operate and maintain contract (25 years in length). The majority of the funding is from private finance, which has been specifically raised for the scheme.

In its latest estimate, TfL says the Silvertown Tunnel is now running £13m over budget – up from the £1m increase forecast in December. An investment programme report, to be presented to a meeting of TfL’s Programmes and Investment Committee on March 1, says inflationary pressures have increased the estimated final cost to £186m.

The tunnel’s opening date has also been pushed back from April to June 2025 because of shortages of skilled labour and materials supply problems, the report says.