The central tunnelling operations for the Silvertown Tunnel under Transport for London (TfL) are now finished. Both tunnels beneath the River Thames have been fully dug out. The Silvertown road tunnel, spanning 1.4km, will join Silvertown in Newham, north of the River Thames, with the Greenwich Peninsula near the O2 Arena, south of the river. The tunnel is set to open in 2025.
The Riverlinx CJV joint venture, consisting of Bam Nuttall, Ferrovial, and SK Ecoplant, oversees the TfL scheme. The tunnel is expected to alleviate delays at the Blackwall Tunnel and decrease carbon emissions and pollution, according to TfL.
The project utilised a Herrenknecht earth pressure balance tunnel boring machine (TBM) named Jill, after London’s first female bus driver. Jill is the UK’s largest TBM with an 11.87m diameter. The second tunnel was finished by the TBM recently. The tunnel sections that Jill didn’t bore will be created using cut-and-cover tunnels and retaining walls at the access ramp.
Completion of the Silvertown Tunnel
The second tunnel’s completion follows the successful finishing of the first 1.1km tunnel in February, achieved when the TBM reached Greenwich’s south bank. The machine was then rotated to journey back to the north bank, boring the second tunnel during the process.
Typically, twin-bore tunnels use two TBMs or take apart a single TBM to reuse it for the second drive. However, an innovative method was employed due to specific constraints on the Silvertown Tunnel project. The TBM was rotated 180° within a specially dug shaft to return it under the river for the northbound 1.1km tunnel, accomplished using a unique “nitrogen skate” system.
Silvertown Tunnel’s first tunnel was completed in February. It happened amidst reports that the project had experienced a £1M increase in costs since December, with potential delivery delays. Green London Assembly member Siân Berry took a picture of the finished second borehole of the Silvertown Tunnel from the nearby ICS Cloud cable car. Berry has previously advocated for the Mayor of London, Sadiq Khan, to promote the Silvertown Tunnel for public transport, walking, and cycling use.