Work is underway on Grain to Tilbury, where we’re building a new tunnel under the Thames and upgrading overhead lines between Grain, Kingsnorth and Tilbury.
What is happening?
A new tunnel beneath the River Thames, replacing the current 1960s cable tunnel between Tilbury and Gravesend, which carries high‑voltage electricity cables and is nearing the end of its operational life. Upgrades to existing overhead lines between Tilbury, Kingsnorth and the Isle of Grain. This will increase capacity so more electricity can be transported across the network.
Why is it happening?
By upgrading the tunnel and overhead lines, more power can be transported from where it is generated to where it is needed. The project forms part of The Great Grid Upgrade, the largest overhaul of the electricity grid in generations. It will enable us to carry more home-grown clean energy, while boosting Britain’s energy security and helping to meet the growing demand for energy.
Latest update
In March, we launched our tunnel boring machine. She’s called Caroline and weighs in at 270 tonnes - equal to a loaded Boeing 777. Caroline will be constructing the entire 2.2km tunnel under the Thames over the next eight months. To create a shaft big enough for Caroline, we used Europe’s biggest ‘vertical shaft machine’. It measures 15m wide and 48m deep and we are now doing the same at Gravesend where the tunnel connects. Our two shafts in Tilbury and Gravesend are now complete and we're well underway with building the tunnel under the Thames.
Meanwhile, our overhead line teams have started a programme of maintenance and upgrades. The works started in mid-April near the Kingsnorth Power Station. Over the next seven months, they’ll make their way along the route making sure the infrastructure is fit for the future.
If you’re interested in reading more about Caroline, the engineering involved, or the works in general, visit our dedicated Our works page.
Building Grain to Tilbury
Watch our short video to find out more about what we need to do to replace the tunnel under the River Thames.
Project timeline
Jan - Apr 2025
Planning applications approved and sites set up in Tilbury and Gravesend
Oct 25 - Mar 26
Tunnel works begin at Tilbury and Gravesend
Apr - Oct 2026
Overhead lines works underway
Nov 2026
Main tunnel drive complete
2028
Works complete
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Contact us:
- Email at [email protected]
- Call us on 020 3398 1599
- Write to us at Freepost Grain to Tilbury project
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The Great Grid Upgrade
The Great Grid Upgrade is the largest overhaul of the electricity grid in generations. Our infrastructure projects across England and Wales are helping to connect more renewable energy to your homes and businesses.