The preferred route for the multi-million pound Western Link, to connect the A47 to the Norwich Northern Distributor Road, has been agreed.
It was done so against a backdrop of protesting by climate change campaigners who gathered outside County Hall.
Norfolk County Council's Conservative-controlled cabinet today agreed to £153m Option C as their favoured route for the road.
That is a 3.9-mile road from the A1067, travelling halfway between Weston Longville and Ringland, and linking to the A47 at a new junction at Wood Lane near Honingham.
It would require a 720-metre-long viaduct over the River Wensum, but the council says discussions with the Environment Agency and Natural England have led them to understand an appropriately designed and built viaduct would be acceptable, even though the River Wensum is a special area of conservation and a site of special scientific interest.
Officers had said Option C stacked up best in terms of environmental impact, value for money, support, transport benefits and impact on local communities.
But Extinction Rebellion, which occupied the council chamber in protest against the road at a previous meeting in February, leading to arrests, urged the council not to back the road.
They staged a demonstration outside County Hall where they created a mocked-up river, complete with pink boat.
They sang protest songs and held placards and banners with slogans such as 'Protect The Wensum Valley', 'Vote Earth' and 'Toads Not Roads'.
Only a handful of protesters were allowed into the meeting, which council leader Andrew Proctor said was due to security procedures.
The route would go through a county wildlife site and would lead to the loss of woodland - a move being opposed by owners of that land.
But the council says it would be mitigating that, planting trees and creating new habitats.
The council says it would aim to achieve biodiversity net gain - so the project would leave habitats in a better condition than before construction.
With barbastelle bats on the new road's route, officers said mitigation, including bat underpasses and bat bridges, would be installed.
Supporters of the road include the Norfolk and Norwich University Hospital, Norfolk Chamber of Commerce, Norwich Airport, Norfolk Constabulary, Norfolk Fire and Rescue, the New Anglia Local Enterprise Partnership, Road Haulage Association, First buses, Konectbus and city and district councils.
Council leader Mr Proctor said: "We all accept whatever decision we make it is not going to please all the people all of the time, but there is strong support for the road itself."
The preferred route was agreed by nine votes, with one abstention.
Bill Borrett, who represents Mattishall, had abstained, saying people in villages such as Hockering, East Tuddenham and Swanton Morley, preferred option D.
In public consultation, that option, nearer to Norwich had proved most popular, but officers had recommended option C.
The road will still need to secure planning permission and funding, but the council hopes construction can start in 2022, with the road open in 2025.
The council also agreed to bring forward around £1.5m of spending on the Norwich Western Link to maintain the project's timetable.
Speaking after the meeting, Amescorr Wilson, from Extinction Rebellion Norwich, said the group would continue to oppose the road.
She said: "We didn't come here expecting to stop it, but to raise awareness and get our message out there.
"From a personal point of view, if it comes to sitting in front of a bulldozer, that's what I will do.
"We have to put our bodies and our safety on the line."
Jenn Parkhouse, from the Wensum Valley Alliance, said: "If, in 2005, the council had to abandon plans for the link road because of the impact on the environment and the cost, 14 years later what has changed to make it viable, given we now face a climate emergency against the backdrop of austerity?"
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