After several years of work to prepare the ground, tunnelling has started on the Silvertown road tunnel linking Blackwall and North Greenwich. Due to open in 2025, it aims to reduce road congestion in the approaches to the existing Blackwall Tunnel, but it hasn’t been without controversy over concerns of increased pollution and the cost of the tunnel.
Since construction work on the Silvertown Tunnel project began in 2020, a huge amount of work has been delivered to prepare for the start of tunnelling, including the delivery of the launch chamber for the tunnel boring machine (TBM), a conveyor system built to remove excavated materials and also repairs to the river wall made to ensure it is not affected while tunnelling takes place.
Aside from a small section around the tunnel entrances, which will be built using a ‘cut and cover’ technique, the two bores that make up the Silvertown Tunnel are being built using one 82 metre-long TBM, named ‘Jill’ in honour of Jill Viner, the first female bus driver in London.
In general, road tunnels are much larger than railway tunnels, and this new TBM’s cutter head has a diameter of 11.9 metres, which compares to 10.025 metres for HS2’s tunnels and 7.1 metres for Crossrail’s tunnels. It also has an exceptionally heavy tunnelling shield, needed to cope with tunnelling under the river. It weighs 1,200 tonnes, compared to 526 tonnes for the heaviest Crossrail tunnelling shield.
Now launched, it will progress under the river at around 10 metres every day and once the first tunnel is completed, will then be turned around to head back to Newham and complete the second tunnel.
Around 780 people are working full-time on the project, including a number of local apprentices.
The project will excavate nearly 600,000 tonnes of material to form the tunnel, which will be taken away by barges along the river where it will be reused to landscape contaminated land at Ingrebourne for a wildlife reserve and also at Rainham Marshes.
The project is being delivered by the Riverlinx consortium, through a design, build, finance, operate and maintain contract. The vast majority of the £1.2 billion cost of the tunnel is coming from private finance which has been specifically raised for this scheme.
Alongside the tunnelling, Riverlinx will be shortly commencing work to realign the road network in Newham and Greenwich to link in with the new tunnel. TfL and Riverlinx are also working on the designs for the walking, cycling and landscaping improvements, which will be delivered around either side of the tunnel entrances. These will see new dedicated cycleways and footways, as well as ‘shared space’ and new public realm installed across Tidal Basin Road roundabout, which will link in with wider improvements planned by Newham Council across the Royal Docks area.
Once the Silvertown Tunnel is open, the total number of buses running through both Blackwall and Silvertown Tunnels will increase, with TfL committed to running at least 20 zero-emission buses per hour through the tunnels at peak times. TfL expects the overall provision of buses through the area could further increase to 37 buses per hour over time as new developments, including at the Royal Docks and Greenwich Peninsula, are completed during the next decade.
Helen Wright, Head of the Silvertown Tunnel programme at Transport for London (TfL), said: “The start of tunnelling is a huge step forward for this project and we are committed to working hard to ensure that it is delivered with minimal impact to Londoners. As well as reducing congestion and providing better cross-river bus opportunities, the new tunnel will also help deliver a wide range of local improvements, including dedicated walking and cycling infrastructure and new landscaping.”
When the tunnel opens, both the new Silvertown and the existing Blackwall tunnels will become toll tunnels and drivers will need to pay to use them. The prices haven’t been announced yet, although TfL says a discount will be offered to local low-income residents.