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Broadcasters Stephen Fry and Chris Packham have thrown their support behind the campaign to stop the controversial Norwich Western Link, calling for a rethink on the £198m project.
Packham and Fry, who grew up in Norfolk and is known for his links to the county, are among 23 prominent local figures, climate experts and politicians to have signed an open letter organised by the Stop the Wensum Link group calling for a rethink on the proposed route.
The scheme to build the 3.9-mile road that would connect the Northern Distributor Road (NDR) to the A47 west of Norwich has been beset by problems in the last year, from rising costs to consultation delays.
The £198m project has been put forward by Norfolk County Council, which insists it will tackle existing traffic problems and help cut overall carbon emissions from vehicles.
But the Stop The Wensum Link group is campaigning to halt the project, citing environmental and economic arguments against it, reports the Local Democracy Reporting Service.
Their new letter states: "The county is blighted by the construction of car-dependent homes which in turn fuel the need for more and more road building, a vicious circle which must be broken.
"Norfolk is faced with a once-in-a-generation opportunity to change direction. Let's make sure it is not lost."
As well actor and writer Stephen Fry, other signatories include wildlife broadcaster Chris Packham, writer Richard Mabey, UEA professors Rupert Read, Iain Barr and Catherine Rowett as well as current and former MPs Clive Lewis and Norman Lamb.
Their letter also criticises the Greater Norwich Local Plan (GNLP), a set of blueprints for building more than 50,000 homes across the region over the next two decades.
The group say the GNLP targets are both unrealistic and the lack of sustainable transport options make it outdated.
Road expansion proposals put forward in the local transport plan also drew concern from the group, which it said was "based on massive and environmentally damaging road expansion in Norfolk to 2036, with no link between transport and housing planning."
The group calls on planners to focus on creating opportunities for more physically active and less isolated lives with less traffic.
It said: "There is nothing to stop Norfolk County Council maintaining a healthy local economy, and turning its attention to how this can be gained without having to be led by reliance on fossil-based transport options.
"Attaining a strong economy and ensuring good transport and housing planning are not incompatible, they just need to be linked and have at their heart action on the climate crisis."
On Wednesday, Norwich City Council voted to reject plans for the Norwich Western Link.
At a meeting of the county council on Wednesday, Andrew Proctor, leader of the authority said the road continued to have "wide support" and that there was no evidence it had lost any backing.
"We are in agreement that there are significant traffic congestion issues in communities to the west of Norwich and, with population and job growth in Greater Norwich, they will continue to worsen unless we take action," he said.
Mr Proctor said 2018 assessments had shown alternatives to the road, including additional bus services, would not be as successful at reducing traffic issues.
He insisted the road would cut congestion and speed up emergency services.