A 3.4km tunnel beneath Wales’ Dwyryd Estuary has been completed, clearing the way for new high-voltage electricity cables in Eryri National Park.
Hochtief UK’s tunnel boring machine, Buddug, broke through into a 57-metre-deep reception shaft after excavating between Minffordd and Llandecwyn. The work began in May 2025 and involved tunnelling through varied geological conditions beneath the estuary.
What happens next
The tunnel is part of National Grid’s Eryri Visual Impact Provision project. It will house new 400kV cables, replacing an existing overhead connection supported by 10 pylons across the landscape.
Once the underground link is operational, the pylons and overhead line will be removed. That will reduce the visible impact of electricity infrastructure in the protected national park.
Work now moves on to removing Buddug, installing the cables and completing the headhouses and other infrastructure at either end of the tunnel. Local school pupils and community members were among those invited to learn about the tunnelling operation and mark the breakthrough.
Why it matters for Britain
The project will keep an important electricity connection while helping preserve the visual character of Eryri National Park. It also shows how major infrastructure can be designed around sensitive Welsh landscapes.
