National Grid Launches 271-Tonne Giant Machine Beneath the River Thames

A critical milestone has been reached on the Grain to Tilbury project, part of the modernisation of the UK’s national electricity grid. The giant 271.5-tonne tunnel boring machine (TBM) has set off to build a 2.2 km tunnel beneath the River Thames.

Caroline: The Giant Machine Going Under the Thames

The machine, which weighs as much as a fully loaded Boeing 777, was ceremonially launched by UK Energy Minister Michael Shanks. The TBM’s name, “Caroline”, honours Caroline Haslett, a pioneering electrical engineer and strong advocate of women in engineering. A co-founder of the Women’s Engineering Society, Haslett’s legacy continues to inspire efforts to widen participation in STEM. The name was chosen through a competition involving local schools.

Why This Project Matters

The Thames Cable Tunnel has carried electricity beneath the river between Essex and Kent since 1969. After more than half a century, renewing the infrastructure had become essential. The Grain to Tilbury project is critical to ensuring the uninterrupted flow into the grid of secure, clean, home-grown energy from more affordable sources.

Energy Minister Shanks commented: “This major engineering project is part of the biggest modernisation of Great Britain’s electricity grid in a generation. It will not only boost jobs and growth but help deliver lower-cost, home-grown clean power to homes and businesses, and free us from the ups and downs of fossil-fuel markets.”

Regional Employment and STEM Commitment

Beyond technical excellence, the project has a strong social dimension. 76 people from the region are currently working on the project, and 15 local businesses support the supply chain. The project will support 22 apprenticeships and numerous graduate positions; students will take their first steps into the energy sector through three-week work-experience placements.

National Grid and its project partners are running an extensive collaboration with local schools to promote STEM education and make career opportunities in the energy sector visible.

International Engineering Collaboration

This milestone is the product of coordinated work by National Grid, the tunnelling specialist Ferrovial BEMO joint venture and TBM manufacturer Herrenknecht. Ferrovial BEMO Project Director Borja Trashorras highlighted the teamwork and technical expertise throughout the process.

Tunnel Construction and Infrastructure Engineering

Power transmission lines passing beneath major waterways such as the Thames require the use of advanced engineering technology, above all tunnel boring machines. Trenchless technologies play a decisive role in such projects: long-distance infrastructure connections can be built without disturbing the river bed and with minimal environmental impact. The Grain to Tilbury project shows once again how strategic this approach is in large-scale energy infrastructure.