Buddug breaks through as Eryri VIP project reaches major tunnelling milestone

Since tunnelling began in May 2025, Buddug has excavated the tunnel between Minffordd and Llandecwyn beneath the Dwyryd Estuary. Along the route, the tunnelling team successfully navigated challenging and varied geology beneath the estuary. Once complete, the tunnel will house the new electricity cables that will replace the section of overhead line and 10 pylons that currently cross the landscape within the Eryri National Park.

The TBM breakthrough is a globally recognised moment in the tunnelling industry, signalling the successful completion of a challenging stage of construction. For the Eryri VIP project team, it represents the culmination of years of planning, engineering and construction activity involving National Grid, its main contractor Hochtief UK, and its delivery partners.

To receive Buddug at the end of her journey, the project team constructed a 57-metre-deep reception shaft at Llandecwyn. The shaft will now be used to remove the TBM from the ground before work begins on the next stage of the project.

Steve Ellison, Senior Project Manager for the Eryri VIP project, said:

“The breakthrough of Buddug is a fantastic achievement and a significant milestone for everyone involved in the project. Completing a 3.4km tunnel beneath the Dwyryd Estuary has required expertise, innovation and teamwork from a wide range of specialists.

“I would like to thank our delivery partners, the tunnelling teams and the local communities who have supported the project throughout this phase of construction. While tunnelling is now complete, there is still important work ahead as we prepare to install the new cables and continue construction of the tunnel headhouses.”

The TBM breakthrough was marked with a series of events for stakeholders, local school pupils and members of the community, providing an opportunity to learn more about the tunnelling operation, geology, view footage from inside the tunnel and celebrate the progress made on the project.

With the tunnel now complete, the project will move into its next construction phase. This includes removing the TBM, installing the new electricity cables within the tunnel and continuing the construction of infrastructure required at either end of the route. 

Once the new connection is operational, the existing overhead line crossing the Dwyryd Estuary and its pylons will be removed, helping to reduce the visual impact of electricity infrastructure within the landscape of the National Park.