M4 relief road would 'damage historic landscape'
Plans to build an M4 relief road would cause "major" damage to nationally important historical landscapes in Wales, conservationists have said.
The £1.1bn six-lane motorway aims to relieve congestion on the motorway between Magor and Castleton.
But the Campaign for the Protection of Rural Wales (CPRW) has accused the Welsh Government of failing to protect the character of the landscape.
The Welsh Government has set out mitigation works for the scheme.
In evidence to the public inquiry in Newport on Wednesday, CPRW chairman Peter Ogden said the road would cause "irreversible damage" to distinctive landscapes.
The Welsh Government's preferred route - known as the "black route" - cuts across the Gwent Levels and four Sites of Special Scientific Interest (SSSI).
He said the government study given to the inquiry underestimated the impact of the motorway on the "undisturbed character and tranquil nature" of the area.
A combination of lighting, traffic volumes and a proposed bridge crossing the River Usk, would create "unacceptable change" and "clutter" to the Gwent Levels, he said.
The landscapes of Wales were "finite resources" and had been shaped over hundreds, if not thousands of years, he added.
Mr Ogden accused the Welsh Government of breaching its own national policies with the proposals, including the Wellbeing of Future Generations Act.
He said if the preferred route was to be built it would fail the planning sustainability test, which the Welsh Government is legally obliged to fulfil.
The Welsh Government's counsel, Morag Ellis QC, accused Mr Ogden of not reading all the evidence with regards to the proposed route.
She said without having read it, Mr Ogden was not able to come to the conclusion that the "Welsh Government was wrong".
In its rebuttal, the Welsh Government said its environmental statement acknowledged the importance of the Gwent Levels and the "significant" effect the building of the road would have.