A £160m viaduct could be built to carry the 'missing link' of the Norwich Northern Distributor Road over the Wensum Valley.
Council bosses have even looked into whether a tunnel could be built beneath the valley, which is deemed to be of special scientific interest.
Councillors will next week be asked to agree to spend £1m – at a time when Norfolk County Council is looking to make £125m of savings – to come up with a business case and preferred route.
A long-standing criticism of the NDR, which will stretch from the A47 at Postwick to the A1067 Fakenham Road, is that it does not join the A47 to the west of the city.
Such a link was previously ruled out because of the cost of crossing the Wensum Valley.
But the Conservative administration has made the western link a priority and made more than £400,000 available to explore how it could happen.
A report, which will come before councillors next week, says a viaduct, carrying a dual carriageway over the valley, has been assessed as being 'high value for money'. It has not been ruled out by Natural England and the Environment Agency.
But the tunnel idea has been assessed as being low value for money and concerns over groundwater flow is likely to be a 'showstopper' for that option.
While a notional route, from near the new NDR roundabout at Taverham to Easton, was used to figure out the potential cost, the council stressed there is not yet a preferred route.
And how it would be paid for will also need to be worked out, with borrowing, government cash, New Anglia Local Enterprise Fund money and developer contributions all being considered.
The council says initial traffic modelling shows, unless the link is built, roads to the west of Norwich will see increased queues and delays once the NDR opens.
Martin Wilby, chairman of the council's environment, development and transport committee, said: 'This is an important project for Norfolk with a number of significant benefits.
'Following the completion of the Northern Distributor Road, the Norwich western link will further help to improve journeys into and around the west of the city, support potential housing and jobs growth and provide the infrastructure to manage the additional traffic this will create, and improve quality of life for people living in the area.
'I'm very conscious of the potential environmental impact of this project, and we have objectives that the Norwich Western Link should improve the quality of life for local communities and also protect and enhance the natural environment.
'With this in mind, and with the evidence so far supporting the case for the project, I hope we can continue with the excellent progress we've made to date.'
But Jenn Parkhouse, of the Wensum Valley Alliance, said: 'It was disregarded before because of the environmental impact and the cost, so what's changed? It's still a site of special scientific interest, it's still a special area of conversation.
'And, if anything, austerity means we are in even more dire financial straits than we were before.
'It defies belief. We are still waiting to find out what the final cost of the NDR will be and they are considering spending a massive amount of money on another road scheme. It's like a bottomless pit. It's crazy.'
She said it would make more sense – and cost less money – to make improvements to the B1535, which connects Fakenham Road
to the A47 via Weston Longville.
What do you think? Let us know in the comments below.
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 bridge 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.
A 'significant number' of species surveys are likely to be needed.
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