Drivers on the A12 are set to be hit by closures while "crucial" works are made.
Contraflow and overnight closures will take place from today (February 19) on the major road, which runs through east London, Essex and Suffolk.
The measures are part of the A12 Margaretting bypass concrete road scheme, said to be 60 per cent complete and at a "crucial" stage.
National Highways, the government-owned company which maintains England's motorways and major roads, said March's overnight closures will run from 8pm until 6am when traffic is at its lowest level.
In February, junction 15 on the A12 (Three Mile Hill/ Webb's Farm Interchange), the southbound entry slip road, will shut from today until Saturday (February 24).
From March 1, the A12 southbound will be shut overnight between junctions 16 and 13. The northbound stretch will also close between junctions 12 and 15 at night.
During this period, two lanes will be kept open in each direction to facilitate traffic flow and provide a safe working area for National Highways staff.
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The A12 northbound will also be closed overnight between junctions 12 and 15 on March 3 and 4.
Nisar Ahmad, National Highways project manager, said: "We would like to thank road users and local communities for their patience during the scheme and can confirm we are now 60pc complete.
"We are doing all we can to minimise disruption – this includes working overnight and at weekends when the road is less busy," he added.
National Highways said it has remade more than seven miles of the A12 carriageway to improve the road surface, reduce noise and extend the road's lifespan by 40 to 50 years.
More than six kilometres of drainage and three kilometres of safety barriers have been installed, it added.
Mr Ahmad said: "The A12 is one of the region's most important roads and carries 80,000 vehicles each day helping to connect London with Essex ports.
"Drivers should allow extra time during their journey and follow the official diversion route signed," he said, referring to when the changes come into effect.
More information can be found on the scheme webpage at: www.nationalhighways.co.uk/A12Margaretting.
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