First bore of Silvertown Tunnel completes
BAM’s joint venture partnership with Ferrovial and SK ecoplant hits major milestone.
- New public-transport focused tunnel will reduce congestion and improve reliability and resilience at Blackwall Tunnel
- 82m-long TBM now being rotated in sections ahead of tunnelling second bore in coming weeks
London, 24 February 2023 - Jill, the Tunnel Boring Machine (TBM) delivering the Silvertown Tunnel in east London, has reached the rotation chamber in the Greenwich site, completing the tunnelling of the first bore.
The TBM, named in honour of Jill Viner, the first female bus driver in London, completed its 1.1km (1106m) drive on 15 February 2023.
Once open in 2025, the twin-bore 1.4km Silvertown Tunnel will link Newham to the Greenwich Peninsula and provide improved bus links across the Thames. By reducing congestion at the Blackwall Tunnel, providing new cross-river bus links and creating a more reliable river crossing for cars, vans and lorries, it will support economic growth across east and southeast London.
Silvertown Tunnel will also provide better access to new job opportunities and support new housing and business developments across the wider area.
What the work involves
The project is being delivered by the Riverlinx CJV, who are a joint venture contracted by TfL and Riverlinx SPV comprising of three civil engineering and construction companies: BAM Nuttall, Ferrovial Construction and SK ecoplant. The project is being delivered through a design, build, finance, operate and maintain contract, with the vast majority of the funding for the new tunnel is coming from private finance which has been specifically raised for the scheme.
Aside from a small section around the tunnel entrances, which will be built using a ‘cut and cover’ technique, the two bores that make up the Silvertown Tunnel are being built using one 82 metre-long, 11.9 metre-diameter TBM. The TBM averaged around 18 metres a day during the delivery of the first bore as it worked its way under the river from Newham to Greenwich. The conveyor system, built to remove excavated materials, has helped transport around 275,000 tonnes of spoil from the tunnel via barge as well as spoil from the retrieval chamber of the TBM and other civils work within the Newham site.
Rotating the TBM
Having arrived at Greenwich, the TBM will now be rotated around in pieces within a 40m rotation chamber, before beginning its 1.1km journey back under the river to the Silvertown site in Newham in the coming months. The process will involve sections of the TBM being placed on ‘nitrogen skates’ within the rotation chamber and turned around before boring the second tunnel. This is a highly innovative and complex process, where the individual sections of the TBM, including the 1200tn cutting shield, will be spun 180 degrees inside a shaft and then reassembled and reconfigured to facilitate tunnelling the second bore back to Newham.
Once tunnelling recommences, spoil from the second tunnel will be fed back via the conveyor systems installed within the first tunnel to allow it to also be removed by barge from the Newham site. The second bore is expected to be completed by the end of Summer 2023.
Helen Wright, Head of the Silvertown Tunnel programme at Transport for London (TfL), said: ‘The completion of the first bore of the Silvertown Tunnel is a huge milestone for the project. Work is now underway to rotate the TBM within the rotation chamber, which is an innovative and complex process, so tunnelling the second bore can begin in the coming weeks. We are committed to working hard to ensure that this project is delivered with minimal impact to those living, working and visiting the local area and have extensive monitoring in place to ensure than this continues to be the case during and after construction.’
Juan Angel Martinez, Project Director at Riverlinx CJV said: ‘We are extremely proud of the team we have delivering the construction for the Silvertown Tunnel project. The solutions we are implementing are pioneering for the UK market and 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.’
Significant progress has been made on both sides of the river. Work on the two tunnel portals is progressing well, and piling and concrete pores for the foundations for the cut and cover sections of the tunnel, as well as the portal entrances, are also now well underway. Repairs have also been made to the river wall at Newham to ensure they are not affected while tunnelling takes place.
Alongside the construction of the tunnel, TfL and Riverlinx are also actively working on the designs for the walking, cycling and landscaping improvements, which will be delivered around either side of the tunnel entrances.
These will see new dedicated cycleways and footways, as well as 'shared space' and new public realm installed across Tidal Basin Road roundabout, which will link in with wider improvements planned by Newham Council across the Royal Docks area. The proposed landscaping around the tunnel entrances, as well as a green roof on both tunnel portal buildings, will form part of the scheme's commitment to environmental improvements and promote biodiversity across the area.
New bridge over the A102
Construction has also commenced on the new walking and cycling bridge across the A102, which will replace the existing 1960s footbridge with a new, fully accessible bridge built to modern design standards and improved lighting. The new bridge will provide a safe and easily accessible crossing for those walking and cycling, including those using cargo bikes, on the Greenwich Peninsula and has also considered future neighbouring development proposals. The main span of the new bridge will start to be installed later this Spring, and the existing bridge will be kept in use until the new bridge is fully opened.
To follow progress of the TBM as it returns under the Thames, click here.
For more information about the Silvertown Tunnel, please click here.