The National Roads Authority has given details of plans for the new Slane bypass, which would be built 500m from the World Heritage Site at Newgrange.
While the plan has been welcomed locally, it is expected that there will be controversy.
The bridge and the road through the village of Slane, Co Meath, is one of the most dangerous stretches of roads in Ireland.
Over 20 people have been killed in accidents and locals have long campaigned for a bypass around the village.
The NRA is proposing to build the route down river of the present bridge and to the east of the village.
The proposed bypass will be 500m away from the buffer-zone around the World Heritage Site at Brú na Bóinne, which comprises the ancient megalithic tombs at Newgrange, Knowth and Dowth.
It will also impact on the museum dedicated to Ireland's most famous World War I poet, Francis Ledwidge, who came from Slane.
The Environmental Impact Statement for the project acknowledges that 44 archaeological sites will be within 500m of the roadway and that the potential to uncover much more during work is high.
While there will be a visual impact from the river, the Environmental Impact Statement says there will be negligible impact on the site.