The A151 and A17 will be closed later this month to allow contractors to carry out work on the Peppermint junction in Holbeach.
A full road closure lasting around six weeks will begin on the A151 from 7am on Monday, July 24.
The signed diversion route will be via the A151 to the A16 to the A17.
A full night-time closure of the A1 between the hours of 7pm to 6am for 10 days will also start on the same day.
During the closure, the signed diversion route for the closure will be via the A1101 to the A47 to the A16.
Both temporary closures will include weekend days and are subject to reasonable weather conditions.
Access to businesses and residences will be maintained throughout the works.
The £5.4 million works will see the current junction replaced with a roundabout connecting the A17 to the A151.
A second roundabout will provide access to housing and commercial development land for a South Lincolnshire Food Enterprise Zone and the proposed Holbeach West housing development.
Councillor Richard Davies, responsible for highways and transportation at Lincolnshire County Council, said: “Contractors are nearly finished carrying out a range of early works, including constructing manholes, extending culverts, carrying out drainage works, digging trenches and diverting overhead power lines. In fact, the team is now ready to start laying tarmac on parts of the new roundabout.
“Due to the nature of the works, there will inevitably be some temporary disruptions, so we ask for your patience as any short-term inconvenience will be greatly outweighed by the long-term benefits this scheme will bring when complete early next year.”