Alternating closures of the northbound and southbound A1, between Little Ponton and Harlaxton, will be in place from early June until late September.
The night-time closures will be in place from 8pm to 6am, weekday evenings only, starting on Monday 1 June for four months.
The schedule of closures is as follows (subject to change as works progress):
- Southbound A1 closure – Monday 1 June to Tuesday 3 August
- Northbound A1 closure – Wednesday 4 August to Friday 10 September
- Southbound A1 closure – Monday 13 to Friday 17 September
- Northbound A1 closure – Monday 20 to Friday 24 September
The diversion route for the northbound A1 closures will be via the B1174 at Little Ponton through Grantham to Gonerby Moor.
The diversion route for the southbound A1 closures will be via the B1174 at Gonerby Moor through Grantham to Little Ponton.
Cllr Richard Davies, executive member for highways, said: "These closures will allow Galliford Try to safely carry out essential works to the A1 as part of the Grantham Southern Relief Road project.
"The second phase of the scheme, which connects the A1 to the B1174, is set to be finished this autumn.
"Meanwhile, construction of the third, and final, section of Grantham's new relief road is underway now, with the team focusing on earthworks and drainage works ahead of building the new River Witham bridge and tying the road into the A52 at Somerby Hill..
"As a whole, this massive project is coming along well and we're still on track for having the whole relief road opened by the end of 2023."
The Grantham Southern Relief Road project is being led by Lincolnshire County Council and supported by South Kesteven District Council, Greater Lincolnshire LEP, Highways England, Department for Transport, Network Rail, Homes England and local businesses.
For the latest news on the Grantham Southern Relief Road, visit www.lincolnshire.gov.uk/majorprojects.