The consortium delivering the design and build of the controversial Silvertown Tunnel has announced the factory acceptance test of what it said is the largest diameter tunnel boring machine (TBM) to be used in the UK.
The Riverlinx Construction Joint Venture (BAM Nuttall, Ferrovial Construction and SK Ecoplant) said the machine that will be delivering the new river crossing’s tunnelling works, built by Herrenknecht, passed the factory acceptance test earlier this month.
The first pieces have already begun to arrive on site ready to be put into action in the spring.
BAM Nuttall said the 11.91-metre diameter of the TBM is the equivalent of almost three double decker buses. This is wider than the TBMs used on the Crossrail project (7.1m), the Northern line extension (6.03m) and Thames Tideway project (8.85m). The machine will also be larger in diameter than those used on the HS2 project.
It is approximately 82 metres long and weighs 1,800 tonnes, two-thirds of which is the shield. BAM Nuttall said the heaviest Crossrail TBM shield weighed in at 526 tonnes, while shields on the Northern Line Extension and Tideway TBMs weighed 310 tonnes and 780 tonnes respectively.
Juan Jose Bregel, project director at Riverlinx CJV, said: ‘It gives me and the delivery team an enormous sense of pride to have reached this important milestone for the Silvertown Tunnel project.’
Helen Wright, head of the Silvertown Tunnel programme at Transport for London, said: ‘Everyone working on the project looks forward to this impressive machine starting tunnelling in Spring 2022, so we can remain on course to have this vital new river crossing open in 2025.’
The Silvertown Tunnel will be a new 1.4km twin-lane road tunnel under the River Thames, linking North Greenwich and Silvertown, the first new road crossing east of Tower Bridge since the Dartford Crossing was built over 30 years ago. It has been widely criticised on air pollution and climate change grounds.
The TBM will set off from the Silvertown launch chamber and will be rotated and relaunched from the Greenwich Peninsula to excavate the second tunnel, completing a total drive of 2,244m.
BAM Nuttall said the ability to turn the machine around is an important feature of its bespoke design, which also addresses the need for it to navigate its way through the stiff clay layers and boulders in this part of London.
It will excavate nearly 600,000 tonnes of material, which will be extracted by barges along the river.
Due to the weight of the components, and the location of the sites, a combination of barge movements along the Thames, as well as lorry movements, are being deployed to transport the pieces of the machine.