Work on a £16m improvement scheme at Guyhirn with two lanes feeding into it, could begin by March next year, if not sooner.
The likely start date has been revealed by Graham Hughes, service director for highways and transport at Cambridgeshire County Council.
In a briefing note to council leader Steve Count he revealed that the scheme - first announced in December 2014 and "paused in the summer of 2017" - is now back on track and set for an earlier than expected start date.
"The reason for the pause was because of a change of contractors and to remain in control of the budget for the project," he says.
"At the time of the pause it was expected there would be a delay of a year.
"However, the delay has now been for two years to the summer of 2019. Highways England have brought on a new contractor and are working to get the scheme delivered."
He said: "Their work over the past year has brought forward the construction start date from 2023 to March 2021."
Mr Hughes said environmental constraints had to be assessed before investigation work could be commissioned.
These includes concerns about reedbeds close to the A47, impacts on Spined Loaches, possible run off of pollutants in the water course and the flood risk.
"The environmental surveys have been successful, and the ground investigation works are expected to be completed over a two-week period in October subject to licensing."
Mr Hughes said a three-lane roundabout was ditched in favour of a two-lane roundabout and Highways England were confident of an early start, possibly even before next March.
Building work will take a year.
Cllr Count has told schemes that is concerned about other major dualling projects along the A47 that are due to start in 2025 and finish by 2027.
He said the Guyhirn scheme did not impact on these efforts "however if estimates of half a million pounds of aggregate for climate mitigation are correct for dualling, I can only assume Government will rethink for a while."
Last October Highways England revealed it had signed contracts worth £435 million with Galliford Try to road upgrades that include the Guyhirn bottleneck.
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