The preferred landscape enhancement option involves the replacement of an existing section of overhead line with underground cables. After carrying out engineering and environmental studies to investigate various options for crossing the Dwyryd Estuary our team concluded that an underground tunnel is the best method.

Please click on the link below to see a map of the existing transmission line, the proposed tunnel route and the locations for the tunnel head houses and sealing end compound.

Project area overview map


Local stakeholders and the community have welcomed the decision to remove 3km of overhead line and ten pylons between the existing Garth sealing end compound in the west and Cilfor in the east at a number of public events held in summer 2016, winter 2018 and winter 2019.

At the eastern end of the tunnel, careful design will combine the tunnel head house with the sealing end compound to minimise impact. Sealing end compounds are needed where a section of underground cable connects to an overhead line. A tunnel head house would also be required at the west end of the tunnel.

We carefully selected the locations to reduce the visual impact of this electricity infrastructure and again, we worked with our group of technical stakeholders to identify the best locations and designs.

Feedback from public consultation events held at the end of 2018 provided us with ideas for the design of the tunnel head houses and the types of materials that should be used. A design that complements other buildings in the area was overwhelmingly preferred by local people, while a more bold design was preferred at the eastern end.

It’s always important that we consider the potential impact of other proposed new electricity generation in the area. Up until January 2019, this included the Wylfa Newydd nuclear power station, that was proposed on Anglesey.

In early 2019, Horizon Nuclear Power announced their decision to suspend their UK nuclear projects, including their proposed power station on Anglesey. This also meant that a new National Grid connection to Wylfa Newydd was no longer required.

National Grid has always stated that the VIP project in Snowdonia would proceed either alongside the Horizon project or as a standalone scheme.

Taking all the feedback from stakeholders and local people into account, on 6 March 2020 we submitted the planning application to the Snowdonia National Park Authority and Gwynedd Council.

The proposal also included the construction of the two new tunnel head houses which will give access to the tunnel, along with a sealing end compound at the eastern end, which will connect the cables to the overhead line that will remain.

In July 2020, we received planning permission subject to the discharge of a number of conditions from both the National Park Authority and Gwynedd Council. Both planning committees were unanimous in their approval of the project.