The 15th February saw Jill, the 11.9m diameter Herrenknecht TBM delivering the Silvertown Tunnel in east London, reach the rotation chamber in the Greenwich site marking the completion of tunnelling on the project’s first 1.1km long bore.
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.
Aside from a small section around the tunnel entrances, which will be built using cut and cover, the two bores that make up the 1.4km long Silvertown Tunnel are being built using the single TBM which averaged around 18m a day during the delivery of the first bore. 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.
The project is being delivered by the Riverlinx CJV, a JV contracted by TfL and Riverlinx comprising: BAM Nuttall, Ferrovial Construction and SK ecoplant. The project is being delivered through a £1bn 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.
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. The Silvertown Tunnel will also provide better access to new job opportunities and support new housing and business developments across the wider area.