The potential routes - and the multi-million pound price tags - for the road which would join the Norwich Northern Distributor Road to the A47 have been revealed.
Four routes have been unveiled by Norfolk County Council for the so-called Western Link, with the costs ranging from £60m to £161m.
And a 30ft high viaduct could be built over the River Wensum and its flood plains through three of the options, while one would also require a second viaduct over the River Tud.
The £205m NDR, now known as the Broadland Northway, currently ends at the A1067 Fakenham Road. But more than a decade ago there were options to join it to the A47 to the east of Norwich.
That was ruled out at the time because of the cost of crossing the Wensum Valley. Parts of the River Wensum are designated as a site of special scientific interest and it is a special area of conservation.
However, the council has always harboured hopes of linking it and made it one of County Hall's priorities two years ago.
They say talks with Natural England and the Environment Agency suggest a solution can be found - although the scheme would depend on securing funding from the government.
And now they have revealed the options for a route to link to the A47, which they will consult on and hope to attract funding for.
What are the options?
Option A: Single carriageway upgrade to A1067 to Lenwade and B1535 to A47 Wood Lane junction at Honingham, using existing bridge at Attlebridge. Length: 7.2 miles. Cost: £60m. Estimated to carry about 10,000 vehicles a day by 2040.
Option B: New dual carriageway and A1067 upgrade. New route to east of Weston Longville linked to A47 at Wood Lane junction. Two alternatives to link to A1067. New junction at Attlebridge, using current bridge or 2,165ft long viaduct over Wensum, joining A1067 east of Attlebridge. Length: 5.2 miles. Cost: £155m. Estimated to carry about 30,000 vehicles a day by 2040.
Option C: New dual carriageway and A1067 upgrade. Link to A47 at Wood Lane. New junction to take route between Weston Longville and Ringland, crossing Wensum on 2,362ft long viaduct. Length: 3.9 miles. Cost: £153m. Estimated to carry about 32,000 vehicles a day by 2040.
Option D: New dual carriageway and A1067 upgrade. New route west of Ringland, linked to A47 at Taverham Road junction, crossing Wensum on 2,165ft viaduct. Second viaduct over Tud. Length: 3.6 miles. Cost: £161m. Estimated to carry about 31,000 vehicles a day by 2040.
The council says the routes have been published after months of work looking at traffic modelling, cost, value for money, environmental and ecological factors.
Martin Wilby, chairman of Norfolk County Council's environment, development and transport committee, said accepted the link would be costly, but said it would be worth it - and he was confident the council would be able to convince the government to contribute towards the cost.
He said: 'We have a good track record of securing money for schemes, such as the third River Crossing at Great Yarmouth and the NDR and we are confident we can do the same again.
'What we have come up with is four good options, which have their benefits and their challenges, but we will be them out for consultation for everyone to consider.
'We are well aware of the environmental issues but we have had constructive talks with Natural England and the Environment Agency and I have said all along there must be a solution.'
The committee will be asked on Friday, November 9 to approve the shortlist and agree public consultation can run between November 26 and January 19.
The council says extra detail on the routes will be provided then, along with information on consultation events and locations.
The Wensum Valley Alliance and the Norfolk branch of the Campaign to Protect Rural England have criticised the potential Western Link. They are worried about its impact on the environment and countryside.
The Norwich Green Party has also been critical, saying it will undermine efforts to cut carbon emissions and say money would be better spent on more sustainable travel.
What happens next?
Following consultation, officers would put a preferred route to councillors in spring next year.
Permission for the road would have to be secured, as would money to build it. The council will look to the government for money, but contributions from developers are also likely to be sought. The council could also borrow money.
Council officers say, if all goes to schedule, they would want to start work around autumn 2022, with a completion date in 2024/25.
Why is the Wensum Valley important?
Nearly 45 miles of the River Wensum upstream of Norwich has been designated as a site of special scientific interest and it is a European Special Area of Conservation.
The river is important for brook lamprey, bullhead, white-clawed crayfish and Desmoulin's whorf snail.
If a viaduct is built over the River Wensum, environmental organisations will be keen to ensure there is no construction on the river banks, which was a key concern previously.
Other issues which have been raised, in the council's conversations with Natural England and the Environment Agency, include:
Highway run-off will need a 'high degree' of treatment to remove pollutants.
There will need to be an assessment of whether salt sprayed up after the road is gritted could have an impact on the River Wensum.
There will need to be consideration of the effects of shade from the viaducts on species.
A tunnel, rather than a viaduct, was previously ruled out.
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