Working in partnership with National Grid, a new scheme is underway to improve the landscape around the Dwyryd Estuary, in Snowdonia, by re-routing power cables underground.
The existing overhead lines are a highly visible and intrusive feature in one of the UK’s most celebrated protected landscapes. National Grid’s flagship Eryri Visual Impact Provision project is addressing this by constructing a 3.4km underground tunnel beneath the estuary between Minffordd and Llandecwyn, allowing the removal of 3km of overhead lines and 10 electricity pylons.
With specialist expertise in railway tunnels, Network Rail’s Asset Protection team is supporting the project by working closely with National Grid and its contractor, Hochtief UK, to provide engineering assurance for works on and near the railway. This collaboration is helping the project to progress safely and efficiently, protecting vital rail infrastructure while minimising impacts on the railway, local communities and the national park environment through careful coordination of access arrangements, construction safety and environmental compliance.
Tunnel construction is underway with Network Rail so far supporting works where the tunnel passes beneath the railway at Minffordd and Penrhyndeudraeth. In March 2026, the Asset Protection team will again work alongside National Grid during further tunnelling activities at Llandecwyn. The pylons and overhead lines are due for removal in 2029.
The section of overhead line, constructed in 1966, is part of the 400kV electricity route connecting the 400kV Pentir substation near Bangor with the former Trawsfynydd Power Station, now a 400kV substation.
The Eryri project is the only VIP scheme underway in Wales, and one of just five across the UK – alongside schemes in the Dorset National Landscape, Peak District National Park, North Wessex Downs National Landscape and the Cotswolds National Landscape.
Wales and Borders Route Director Nick Millington said: “We’re proud to support the Visual Impact Provision project in Eryri, which aligns with our commitment to sustainability, community engagement and protecting the environment.
“Wales and Borders is more than a railway – and the contribution of our specialist engineering teams to this complex work shows how we work with partners to deliver lasting benefits for our beautiful landscape, while keeping passengers and freight moving safely and reliably.”
Located close to the Cambrian Line and key community access points, the project requires tight coordination between National Grid, its contractors and Network Rail to plan safe construction routes, cable delivery operations and overhead line removal – all while keeping disruption to a minimum. The Cambrian Line remains open during the work.
Network Rail has also worked closely with the Eryri National Park Authority and National Grid’s environmental teams to support access planning and mitigate environmental risks. This includes protecting sensitive habitats and to allow well-used walking routes – including the Wales Coast Path – to remain accessible throughout the works, wherever possible.
Steve Ellison, senior project Manager for the Eryri VIP at National Grid, said: “We’re proud to have completed this important and delicate stage of our tunnelling journey without issue. This is testament to the close working relationship we have with Network Rail and the high level of skill and expertise within both teams.”
Image credit: Network Rail
