Silvertown Tunnel opening advanced to early 2025 as cut and cover and road realignment progress

The opening of Transport for London’s (TfL’s) Silvertown Tunnel has been brought forward to early 2025 while work on the cut-and-cover sections and road realignment works have hit full steam.

Documents from the February 28 meeting of TfL’s Programmes and Investments Committee reveal that the permit-to-use date of the 1.4km tunnel under the Thames has been brought forward to Q4 of 2024/25 (January-March 2025) where it had previously been Q2 2025/26 (July-September 2025) . This is due to a “series of programme mitigations”, according to TfL.

The papers also reveal that the authorised budget for the project has been increased by £2.7M to £176M to include scope for the provision of bus infrastructure. However, the estimated final cost of the project is currently sitting at £180M due to “additional inflation assumptions being included for land purchase”.

Work to build the connection from the Greenwich Peninsula to west Silvertown by Riverlinx CJV (Bam, Ferrovial, SK Ecoplant) is progressing rapidly.

Greenwich site

Domes being installed on the Greenwich cut and cover section

On the Greenwich site, the contractor reports that the steel framework of the southern portal building is complete and cladding work has commenced. Fit out and highway works continue inside the tunnel.

With main tunnelling having completed last year, Riverlinx is now installing domes over the cut-and-cover section of the tunnel, which runs from the southern end of the bored section to the portal structure. Backfilling will commence in the spring and this will allow the reinstatement of Millennium Way, which runs above the southern approach.

Sheet piling has been completed on the tunnel approach and reinforced concrete works to form the walls and base slabs will continue through to mid-2024. This includes works within the rotation chamber, where the tunnel boring machine (TBM) was rotated using an innovative “nitrogen skate” system before being sent back to bore the northbound tube.

Walls and domes being installed within the rotation chamber

A temporary bridge for traffic has successfully been installed over the Silvertown Tunnel southbound approach. This is to allow excavation work to continue below to create the new road alignment.

Utility reinstatement beneath this bridge has also commenced and is expected to continue within the carriageway until the autumn. Once complete, the temporary bridge will be removed and the carriageway reinstated to its usual layout.

The Blackwall Tunnel, which has its south portal adjacent to the Greenwich site, had to close its northbound tube for five weekends during January and February (although it is southbound traffic that is affected as northbound traffic is diverted via the usual southbound tunnel). This allowed drainage and gantry works to be carried out for Silvertown Tunnel. This is progressing as planned with one more closure to occur this weekend, 24 to 26 February.

TfL has now warned that further closures of the Blackwall Tunnel for southbound traffic will take place on the weekends of 16 to 18 March and 13 to 15 April. This will allow engineers to implement the new road configuration required for Silvertown Tunnel and see gantries for over-height vehicles installed. Road resurfacing will also be part of the configuration works.

Silvertown site

Overview of Silvertown construction site, showing domes installed over cut and cover section prior to concrete pour

As on the Greenwich site, the steel framework of the Silvertown portal building has been completed and cladding is underway.

Cross passage excavation, which utilised ground freezing techniques, has completed. Waterproofing has also concluded, which has finalised the tunnelling.

The dome installation over the cut and cover section, from the end of the bore to the portal building, has been completed. The concrete pour on top has also been successfully finished. Utilities and highways works within this section of the tunnel have commenced.

Utilities and highways works within the cut and cover section of the northbound approach

The unique “peanut shaft”, from which the TBM was launched, is now slowly being filled with slabs and walls. This will close the gap between the cut and cover section and the bored tunnel rings. Within this tunnel approach, the base slab for the road has been completed, while the construction of the walls is ongoing.