The Route


The preferred landscape enhancement option involves the replacement of an existing section of overhead line with an underground solution. 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 and our current search areas for the tunnel route and the possible locations for the tunnel head houses and sealing end compound.

Project area overview map

Local stakeholders and the community 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 during public events in summer 2016 and winter 2018.

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.

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 that of other buildings in the area was overwhelmingly preferred by local people.

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 includes the construction of 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. For more information on this application click here.