Highways bosses carrying out the three-year project to dual two stretches of the A47 claim there will be "minimal impact" on drivers during the roadworks.
Fresh details have been revealed about work to dual 5.5 miles of the major Norfolk route between Easton and North Tuddenham and 1.5 miles between Blofield and North Burlingham.
work began in earnest in August.
After years of delays, including those triggered by a legal challenge over the government's decisions to allow the schemes,And engineers from National Highways say progress on the section between Easton and North Tuddenham is ahead of schedule and could open months earlier than advertised.
They also revealed the way much of the work is being done - effectively replacing the current A47 with a new, dualled road running alongside it - means disruption to drivers should be kept down during construction.
Matt Stafford, regional director for National Highways - the government company responsible for the schemes - said: "The way we have designed the projects is to have a minimal impact on the current A47.
"Between Easton and North Tuddenham, the main disruption will not come until late 2026 and 2027, when we 'tie' the new road into the current A47.
"That's when there will be traffic management. But up to that point, there's going to be very little impact."
Chris Griffin, A47 project lead for National Highways, said there would be a need for some closures and diversions, but the majority of the work will see the lane capacity kept the same as at present.
National Highways also hope the Easton to North Tuddenham work will be completed sooner than the summer 2027 mentioned on construction signs.
Compounds which will act as hubs for construction traffic have been built.
And Mr Stafford said work on pilings for structures, including a bridge at Norwich Road and at Wood Lane, had been completed before winter, accelerating what can be done during the colder months.
The good progress, he said, could mean the scheme is finished in spring 2027, with the Blofield scheme ready by summer 2026 - if winter weather is favourable.
National Highways says the schemes will improve safety, claiming the Easton to North Tuddenham dualling will mean one fewer fatality a year, while it will speed up journey times by two to three minutes per trip.
Officers said the schemes had been delayed by 20 months due to a legal challenge by climate campaigner Dr Andrew Boswell.
Dr Boswell had argued the government acted unlawfully in giving those schemes, plus a revamp at Thickthorn junction and roundabout changes at Great Yarmouth, permission, because it had not properly considered the cumulative carbon impact of them all.
But judges at the High Court and Court of Appeal rejected his argument and he was denied the opportunity to have it heard at the Supreme Court.
National Highways said that added "tens of millions" to the price tag of the schemes, but Mr Stafford said it was "difficult" to give a more precise figure.
Officers were also reluctant to put figures on the total cost of all the schemes - which, along with two in Cambridgeshire, were awarded £300m by then prime minister David Cameron in 2014.
But the Easton to North Tuddenham section alone is now likely to cost at least £250m, the Blofield to North Burlingham work about £100m and the Thickthorn revamp up to £100m.
Mr Stafford said: "The costs have gone up, but we have also developed different ways of doing this, which have made savings.
"We are still broadly within the cost envelope originally set for the schemes."
While work at Easton to North Tuddenham and Blofield to North Burlingham, where a major gas line is having to be diverted, has begun, the future of the Thickthorn scheme is uncertain.
The reconfiguration of the junction there - where the A47 meets the A11 on the edge of Norwich - is one of several transport schemes which may be axed after Labour ministers said they had found a £22bn black hole in government finances.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereLast Updated:
Report this comment Cancel