The incredible new £207m tunnel that will transform UK national park

A £207 million tunnel set for completion in 2029 could transform Snowdonia and “enhance the natural beauty” of the area. 

Hochtief UK was awarded the electricity tunnel project by National Grid to reduce the impact of overhead cables in the Welsh national park, as part of the Visual Impact Provision project. 

Two shafts and a 3.4 km tunnel will carry electricity under the Dwyryd Estuary, replacing 3km of National Grid’s overhead lines between Minffordd and Llandecwyn in Eryri National Park, also known as Snowdonia, in north Wales.

Hochtief UK’s Managing Director Lawrence Jackson said: “We are delighted to contribute with our long-standing expertise in tunnelling works to conserve and enhance the natural beauty and environmental heritage of Snowdonia”.

This seven-year tunnel project which started in 2022 reached a major milestone on 18 November when the first of 27 packages of the tunnel boring machine (TBM) arrived, which will be used to excavate the tunnel for the new electricity cables.

The TBM will be ready to commence tunnelling in early 2025, and once assembled, it will measure 166 metres and weigh 436 tonnes.

It’s expected to reach its destination in Llandecwyn in mid-2026, and the pylons and overhead lines are set to be removed in 2029.

National Grid’s senior project manager for Eryri VIP Steve Ellison said: “These deliveries have been many months in the planning and we work hard to minimise any disruption that deliveries of this kind can cause.

“The movements are occurring at these times to try and minimise disruption to the local road network and we appreciate the cooperation and understanding of the local community.”

The 27 deliveries spanned over a three week period, transported from Germany where it was manufactured to the project site in Minffordd along the A55, A487 and A497. 

This is Hochtief’s second tunnelling project for National Grid, also in joint venture for delivering 32 km of tunnels to supply electricity in London.