Work to build a new 2.2km high-voltage electricity cable tunnel under the River Thames has passed the halfway mark.
The tunnel, built by the National Grid, will span between Tilbury in Essex and Gravesend in Kent, replacing the ageing Thames Cable Tunnel which has been in use since the late 1960s.
More than 400,000 tonnes of materials have been excavated since work began in May, with upwards of 5,100 pre-cast concrete tunnel segments installed to form the tunnel lining.
The project comes as part of the National Grid’s Grain to Tilbury project and the wider Great Grid Upgrade – the largest overhaul of the electricity grid in generations.
Mark Farmer, Project Director, National Grid, said: “Reaching the halfway point of tunnelling beneath the River Thames is an important moment for the Grain to Tilbury project and is a testament to the expertise and collaboration of teams across National Grid and our partners.
“The progress made so far reflects the dedication of everyone involved and moves us a step closer to delivering infrastructure that will help strengthen the electricity network and support Britain’s future energy needs.”
The National Grid is working with construction and tunneling partners Ferrovial BEMO JV and Herrenknecht.
The tunneling has been made possible thanks to the 464-tonne tunnel boring machine Caroline, named after pioneering electrical engineer Caroline Haslett.
Borja Trashorras, Project Director, Ferrovial BEMO JV, said: “Reaching the halfway point beneath the River Thames reflects the expertise and collaboration of the entire project team.
“Delivering more than 1.1km of tunnel safely through complex ground conditions, while maintaining strong productivity and environmental performance, is a testament to the planning, engineering and innovation at the heart of this project.
“We’re proud of the progress made so far and remain focused on carrying that momentum forward as Caroline continues her journey towards a breakthrough later this year.”
Ulrich Schaffhauser, board member at Herrenknecht AG, added: “National Grid’s Grain to Tilbury project is a benchmark project in every respect.
“It is impressive to see what can be achieved when tailor-made technology and professional project execution come together.
“Congratulations to the dedicated team on site for reaching the halfway milestone, and best wishes for a safe and successful completion of the tunnel works.”
Other work involved in the Grain to Tilbury project include the full refurbishment of the overhead line between Tilbury, Kingsnorth and the Isle of Grain.
The entire project is expected to be completed in Q1 2029.
