Jill, the TBM which is delivering the Silvertown tunnel in east London, has now completed work on the second bore.
The TBM, named in honour of Jill Viner, the first female bus driver in London, completed the 1.1km (1106m) drive from Greenwich to Newham in late July 2023, after completing the first bore in February 2023, meaning that all main tunnelling works were completed in less than a year.
Aside from a small section around the tunnel entrances being built using a cut & cover technique, the two bores that make up the Silvertown Tunnel have been built using a 82 m-long, 11.9 m-diameter TBM. During tunnelling of the second bore, the TBM averaged around 22 m a day as it worked its way under the river from Newham to Greenwich.
The conveyor system transported more than 780,000 t of spoil to barge. The use of river transport to deliver to or from the site has avoided the need for more than 60,000 HGV and other delivery vehicle journeys to date. All TBM bored materials from tunnelling are being transported along the Thames to a former landfill site in Essex as part of a restoration scheme.
The tunnelling of the second bore follows the successful rotation of the TBM in Greenwich, where it was placed on ‘nitrogen skates’ within a rotation chamber and turned around in a highly innovative and complex process. Spoil from the second tunnel was fed back via the conveyor systems installed within the first tunnel to allow it to be removed by barge from the Newham site.
With the main tunnelling work completed, the team is now excavating the eight by-passes between the two tubes using ground-freezing and building the temporary propping into the cross-passage linings. Ducting which will be located underneath the carriageway within the tunnel is also currently being installed, so that by the end of the year the main road surface within the tunnel can start to be installed to allow for testing and final fitout of the tunnel systems to commence.
Work on the cut & cover sections of the Silvertown tunnel, which includes the portal entrances, continue to be delivered, as well as the new road layout into the Tidal Basin roundabout in Newham, and link roads into the A2 south of the Blackwall Tunnel.
The CJV formed by Ferrovial Construction, Bam Nuttall and SK Ecoplant used innovative and pioneering solutions for the UK such as the TBM rotation and frozen cross-passages. Working together with TfL as well as its many local stakeholders, Riverlinx is now focusing on the next stages of construction to successfully deliver this vital piece of infrastructure for London.
For more information, please click here and uk/77 for tunnelbuilder archive. Visit https://www.riverlinx.co.uk and https://tfl.gov.uk/. 32/23.
