The total length of the tunnels will be built by one tunnel boring machine (TBM) which launched in Silvertown in 2022 and completed the first tunnel in February 2023. It will then turn around in Greenwich to complete the second. We will also use a tunnelling methodology called cut and cover for the entrances on either side.
The TBM measures approximately 82 metres in length, weighs 1,800 tons and has a cutter face of almost 12 metres in diameter.
It won’t have an easy job as the geology of this part of London is stiff clay layers and boulders. It will excavate nearly 0.6 million tonnes of material to form the tunnel. This material will be extracted by barges along the river to keep construction traffic to a minimum during the project.
Construction work has now begun and sites are well established on both sides of the river in preparation for the Tunnel Boring Machine (TBM).