Work on the £300m A47 improvements could all take place at the same time, highways chiefs have said, as they announced preferred routes for dualling sections of the road.
But Highways England bosses have said, in the light of concerns from communities, they are considering whether it might make more sense to phase some of the work, due to start in 2020.
Highways England's Peter Davie, the project's leader, said: 'The commitment is to start in 2020 and we can deliver it in that time frame.
'But from the feedback we have had, we need to see if that is the best way to do it, or whether we need to phase some of the work.'
The government organisation, which has been consulting over the details of the project, has confirmed details of improvements to six sections of the road, which runs for 115-miles between Great Yarmouth and Peterborough.
That includes the dualling of a stretch between North Tuddenham and Easton and between Blofield and North Burlingham.
Between North Tuddenham and Easton, the A47 will be dualled mainly along its existing route, with some re-alignment, rather than options which could have seen a new carriageway to the north or south of the current road.
For the Blofield to North Burlingham dualling, a new stretch of dual carriageway will be built south of the existing A47.
On the Thickthorn roundabout, new slip roads will mean some traffic will avoid the roundabout altogether.
Traffic wanting to get from the city-bound A11 onto the eastbound A47 will join a new slip road travelling under the existing roads to join the A47, while traffic leaving the A47 westbound to get onto the southbound A11 will also do so via a new slip road.
In Great Yarmouth, the Vauxhall roundabout will be enlarged, with improvements to the Gapton roundabout. In Cambridgeshire, the A47 will be dualled from Wansford to Sutton and changes made at Guyhirn.
Highways England is now talking to landowners who could be affected by the work.
Mr Davie also confirmed the North Tuddenham/Easton section had been designed with flexibility in mind, given the possibility of a Western Link from the A47 to the Norwich Northern Distributor Road.
Highways England bosses said the consultation was crucial in helping come up with the preferred routes.
The North Tuddenham to Easton section received the most responses, with 530, while the Blofield to North Burlingham schemes garnered 441 comments.
While the £300m scheme has been welcomed, pressure is now mounting for other improvements in the next round of investment from 2020 to 2025.
Nova Fairbank, from Norfolk Chamber of Commerce, said: 'There is still a significant way to go to bring one of Norfolk's main routes up to standard, even with the current planned improvement schemes.
'Norfolk Chamber and its members will be working in partnership with the A47 Alliance, to call on Westminster to provide funding for further improvements, such as the dualling of the Acle Straight and the dualling of the section between Tilney and East Winch.'
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