National Grid’s giant tunnel boring machine ‘Caroline’ launched by Energy Minister begins journey under the River Thames

A huge 271.5 -tonne tunnel boring machine has begun its journey to construct a 2.2km tunnel beneath the River Thames, marking a major milestone for National Grid’s Grain to Tilbury project.

Weighing the equivalent of a fully loaded Boeing 777 aeroplane, the machine named Caroline was launched today by Energy Minister Michael Shanks. The TBM will excavate the tunnel that forms a critical part of the new infrastructure supporting the electricity network.

The Grain to Tilbury project is vital to ensuring secure, cleaner, home‑grown energy from more affordable sources can continue to flow across the network.

Following a competition involving local schools, the TBM was named after Caroline Haslett, a pioneering electrical engineer and prominent advocate for women in engineering. Haslett was a founding force within the Women’s Engineering Society, and her legacy continues to inspire efforts to broaden participation in engineering and technical careers.

National Grid and its project partners are working with local schools to promote science, technology, engineering and maths (STEM) education and highlight career opportunities within the energy industry. In collaboration with contractors, the project team is developing enterprise and careers hubs, volunteering initiatives and programmes designed to support local skills development and create pathways into employment.  

The project is committed to supporting the local workforce, leaving a lasting skills legacy in the local area. Currently, 76 people from the local area are working on the project, alongside 15 local businesses that are helping to deliver key elements of the work and supporting the wider supply chain.

Training and development opportunities are also being created as part of this commitment. The project plans to support 22 apprenticeships and multiple graduate roles, while students will have the opportunity to take part in three-week work experience placements, giving them practical insight into careers in the energy sector.

Today’s milestone reflects the combined efforts of National Grid, joint venture partner and tunnelling specialist Ferrovial BEMO, and TBM manufacturer Herrenknecht. Together, the teams are delivering this nationally significant infrastructure project with safety as the highest priority.  

Energy Minister Michael Shanks said:

“Since 1969 the Thames Cable Tunnel has transported electricity under the river between Essex and Kent. But after more than half a century, it now needs replacing.

“This major engineering project is part of the biggest upgrade in Great Britain’s electricity network in a generation. Not only will this boost jobs and growth, but it will help get lower cost homegrown clean power to homes and businesses and get us off the rollercoaster of fossil fuel markets.”

Jen Craft, MP for Thurrock, said:

"Today's event was another step forward in this exciting project for the Thames Estuary region.  

"I'm really pleased that Thurrock is at the centre of these vital upgrades to the network, playing our role in the transition to secure, home-grown energy.

"Through strengthening our local electricity network, and providing training and development opportunities for residents, this project is delivering real benefits for my constituents in Thurrock."

Mark Farmer, Project Director, National Grid, said:

“The arrival of the tunnel boring machine is a significant milestone for the Grain to Tilbury project and a major step forward in strengthening the electricity network in this area for years to come. This important project will help ensure secure, cleaner, home‑grown energy can continue to flow across the network as demand increases.

“It was a great privilege to welcome Energy Minister Michael Shanks, along with representatives from Ferrovial BEMO, Herrenknecht and our National Grid colleagues, to mark the launch of TBM Caroline.”

Borja Trashorras, Project Director, Ferrovial BEMO JV, said:

“The launch of TBM Caroline marks a major achievement for our integrated JV, highlighting the strength of our teamwork, technical expertise and our capability to deliver world-class engineering for National Grid.  

“As tunnelling begins, my thanks and congratulations go to everyone whose hard work has achieved this milestone so swiftly with efficiency and excellence.”

Ulrich Schaffhauser, Member of the Board of Management, Herrenknecht AG, said:

“River crossings are key in grid construction, and safety comes first in shaft and tunnel works. In addition to the VSM, which has safely sunk the launch shaft, we are proud to deliver a tailor-made Mixshield TBM for the cable tunnel.

“My best wishes to the team of our partners Ferrovial BEMO JV and National Grid on the launch of the TBM.”

Tim Self, Careers Leader, St John’s Catholic Comprehensive, said:

“We’re really pleased to be working with National Grid and Ferrovial BEMO, and to see such a strong commitment to engaging with our students. The team have provided wonderful support and direction, challenging our students with real-world issues that strengthens their confidence and determination to succeed.

“Opportunities like this help bring learning to life, give young people insight into the world of work, and show them the range of careers that could be open to them in the future. As an educator, it's a delight to see students enthusiastic about the projects they are doing and keen to engage further, and to hear how they reflect on their future pathways through such experiences.”