Contractors Move Ahead with Lower Thames Crossing Tunnel Boring Machine Despite Funding Uncertainty

Contractors for the Lower Thames Crossing have begun preparations to acquire a tunnel boring machine (TBM) for the project, even as the funding model for the scheme remains unresolved.

Bouygues Travaux Publics Murphy Joint Venture, appointed by National Highways to construct the 4km central tunnel, is currently inviting tenders from suppliers capable of producing the massive TBM. The machine will be 16.4 metres wide, making it one of the largest tunnel boring machines in the world, and will create a tunnel accommodating three lanes of traffic in each direction. At over 4km, it will also become the UK’s longest road tunnel.

Funding for the Lower Thames Crossing remains in flux. Chancellor Rachel Reeves recently confirmed an additional £891m in public funding in her autumn budget to complete the publicly-funded portion of the project. Beyond this, the Treasury plans to engage with private investors next year to secure the bulk of the remaining finance. The government has indicated a preference for the regulated asset base (RAB) model, though officials have stressed that the plan could evolve during the market engagement process.

Project costs have risen in recent months, reportedly climbing from £9bn to £11bn, with roughly £3bn expected to come directly from public funds rather than toll revenues.

Despite these uncertainties, the joint venture anticipates purchasing the TBM in 2026, with excavation set to begin in 2028. Preliminary works at the northern tunnel portal, the machine’s starting point, are scheduled for summer 2026.

Matt Palmer, executive director of the Lower Thames Crossing, said: “The search for our giant tunnel boring machine is now underway. This is a crucial step toward opening the Lower Thames Crossing in the early 2030s, enhancing journeys for millions and supporting jobs, business growth, and trade opportunities.”