Washingborough Road will close for at least five months to allow for the construction of the final new Lincoln Eastern Bypass roundabout.
Work will begin on Monday, February 17.
The closure will be from the entrance of the Anglian Water compound in the west to the rail bridge just past the bypass site.
A diversion route will be in place:
The diversion route for HGVs will be via B1188/Lincoln Road to B1202 to B1190, and vice versa.
Washingborough Road is expected to re-open in July, with the completed bypass set to open in the autumn (subject to suitable weather).
Councillor Richard Davies, executive member for highways at Lincolnshire County Council, said: “Starting in February, Washingborough Road will be closed for five months so Galliford Try can make a start lowering the road by approximately 1.5m before carrying out drainage, street lighting and kerbing installation, along with laying road surfacing.
“We’re aware this will be inconvenient for many, so will be doing everything we can to minimise disruption throughout the closure.”
The £120 million bypass project was previously set for a May 2020 competition. This has now been put back to the autumn due to wet weather in recent weeks.
Councillor Richard Davies added: “We’ve experienced extremely wet weather over the past few months which has had an impact on the project’s completion date.
“As a result, we’re now looking at opening the new bypass this autumn.
“I know this isn’t ideal, but the important thing to remember is that the road is being built and we’re months, not years, away from it opening and improving journey times for people travelling in and around Lincoln.
“This scheme has faced challenge after challenge since starting, but the team has continued to make good progress and will continue doing their absolute best to get the bypass open as soon as possible.
“We still expect to deliver the scheme on budget and will continue monitoring spending to ensure this remains the case.”