Highways chiefs and council bosses are locked in a stand-off over how parts of the 'old' A47 will be maintained if proposed dualling goes ahead.
Transport secretary Grant Shapps will have the final say over whether the multi-million pound dualling of sections of the A47 between Blofield and North Burlingham and Easton to North Tuddenham can proceed.
He will also decide whether to approve changes to the Thickthorn junction on the edge of Norwich after a series of hearings to help planning inspectors come up with recommendations.
But Mr Shapps has sent a letter instructing Norfolk County Council and National Highways to explain whether an agreement will be reached over what happens to the current A47 if it is replaced by a new dualled section between Blofield and North Burlingham.
While there is no suggestion the schemes could be scuppered because of the wrangle, the sticking point relates to the passing over of responsibility for around a mile and a half of the 'old' section of the road.
As a major A-road - or 'trunk road' - the A47 is maintained by the government-owned company National Highways. But, if permission for dualling is approved, part of the old road would be 'de-trunked'.
That would see responsibility for it - and the cost of maintenance - pass to Norfolk County Council, as it would become a local road.
And, with the council grappling with a £60m funding gap, the authority is keen to get agreement over what condition any handed over sections of road would be in and to secure money from National Highways to cover the cost of maintaining the de-trunked sections.
Talks have been going on since November 2020, but with no resolution so far - and the impasse has triggered the secretary of state's letter.
In the absence of an agreement, County Hall has lodged what are known as 'protective provisions' with the Planning Inspectorate.
Those would give the council the power to approve detailed plans of some elements of the schemes before they were constructed.
But it would also include a means of establishing how much National Highways would pay the council in a one-off sum to cover future maintenance costs - and an acknowledgement that might have to go for arbitration if no agreement is reached.
The council is seeking those protective provisions to cover roads 'de-trunked' not just by the Blofield to North Burlingham stretch, but also at the Easton to North Tuddenham and Thickthorn schemes.
The council says it has yet to come up with a final figure over how much it might cost to maintain the handed over assets - as that will depend upon the overall extent, size and number handed over, along with their condition.
Should an agreement not be reached, the council hopes Mr Shapps, should he grant permission, would include the council's suggested protective provisions as part of the development consent order.
The letter from the secretary of state gives the council and National Highways until April 27 to respond.
And it stresses: "This letter is without prejudice to the secretary of state’s decision whether to grant development consent for the A47 Blofield and North Burlingham project and nothing in this letter is to be taken to imply what that decision might be."
Grahame Bygrave, director of highways and waste at Norfolk County Council, said: "We are working closely with National Highways on an agreement that would see the county council take on the maintenance of the existing stretch of road, as the new dual carriageway would bypass it.
"This will ensure the responsibilities are clearly set out ahead of the scheme’s completion, and routine maintenance can be carried out.
"These talks will continue as we iron out the details with National Highways and we remain confident that this process will not ultimately affect the delivery of these schemes.”
A spokesman for National Highways said the agency would be responding to Mr Shapps in due course.
The spokesman added: "As standard with all major road projects, we hold discussions with the local authority around the handover of assets, and these conversations are ongoing.
"We will continue to work closely with Norfolk County Council to ensure maximum benefits for all and will provide a further update once a solution has been agreed."
Mr Shapps is due to give his decision over the Blofield to Burlingham scheme by late June.
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