A section of Greetwell Road in Lincoln will close for seven weeks from Monday, October 14.
The closure will be in place just past the mini-roundabout near Wickes, to all traffic, until 6pm on Friday, November 29.
It is subject to weather conditions and includes evenings and weekends.
The diversion route for the closure will be via Outer Circle Road, Bunkers Hill, Hawthorn Road, Croft Lane/Church Lane, Fiskerton Road and Greetwell Road, and vice versa.
Councillor Richard Davies, executive member for highways at Lincolnshire County Council, said: “During the closure, we’ll be carrying out final earthworks, kerbing, street lighting and other essential elements of the new roundabout.
“By the end of the seven weeks, the new Greetwell Road roundabout will be ready for people to drive on, making it the next of four new bypass roundabouts complete.
“I know closures like this aren’t ideal, but they’re a necessary part of building any new major road.
“However, we’ll be doing everything we can to get the road opened back up early, weather permitting.
“We’re making good progress across the rest of the site, including with construction of the new Sleaford Road roundabout and Heighington Road bridge, which are both well underway.
“Once we’ve finished building these major parts of the scheme, the big priorities for 2020 will be building the new Washingborough Road roundabout, completing the new River Witham viaduct and getting the bypass open by the end of spring.”