National Grid and Network Rail Drive Forward Estuary Transformation
A major environmental project is reshaping the landscape around the Dwyryd Estuary in Snowdonia, where National Grid is working to remove a prominent stretch of overhead electricity infrastructure by replacing it with an underground system. The initiative, developed in partnership with Network Rail, aims to restore views across one of Britain’s most treasured protected areas.
At the heart of the Eryri Visual Impact Provision scheme is the construction of a 3.4km underground tunnel between Minffordd and Llandecwyn. Once complete, it will allow National Grid to dismantle 3km of overhead power lines and take down 10 large pylons that have dominated the estuary skyline for decades.
Network Rail’s Asset Protection team is playing a key supporting role, bringing specialist knowledge of railway tunnels to ensure that works close to the Cambrian Line are carried out safely. Working alongside National Grid and principal contractor Hochtief UK, the team is providing engineering oversight to protect rail assets and coordinate construction activities near the line.
Tunnelling work is already progressing beneath the railway at Minffordd and Penrhyndeudraeth, with further activity due at Llandecwyn in March 2026. The full removal of the pylons and overhead lines is scheduled for 2029. The section being replaced dates back to 1966 and forms part of the 400kV connection linking Pentir substation near Bangor with the former Trawsfynydd Power Station.
This is the only VIP scheme taking place in Wales and one of just five across the UK, alongside projects in the Dorset National Landscape, Peak District National Park, North Wessex Downs and the Cotswolds. Its location near the railway and important public access routes requires careful planning to manage construction traffic, cable movements and eventual line removal while keeping disruption to communities and passengers to a minimum. Importantly, the Cambrian Line continues to operate throughout the works.
Network Rail is also collaborating closely with the Eryri National Park Authority and National Grid’s environmental specialists to ensure that sensitive habitats are protected and well-used paths, including the Wales Coast Path, remain open wherever feasible during the project.
Nick Millington, Wales and Borders Route Director, Network Rail, 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.”
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: Network Rail