Highways England will begin around six months of disruptive works to repair the iconic Spaghetti Junction in Birmingham next week.
Work will include renewing the waterproofing of the ageing structure at junction 6 of the M6.
An earlier phase of works at Spaghetti Junction last year caused significant disruption.
Junction 6 of the M6 is the original Spaghetti Junction
The Government-owned company said the new work is unavoidable, but that it has worked closely with Birmingham City Council to plan the roadworks at Spaghetti Junction and on the A38(M) Aston Expressway.
It said it is working to ensure that lane closures and disruption will be minimised where possible and closures of the M6 will be kept to weekends only.
Roadworks will be in place for up to 24 weeks with overnight work from 8pm to 6am and some weekend closures.
However, the company has stressed that engineers can not know the scale of concrete damage until the carriageway is closed and the road surface removed.
Highways England project manager Jess Kenny said: ‘The road was built a considerable number of years ago and has reached the end of its life. We need to work now to ensure this part of Spaghetti Junction is protected for years to come.
‘If we don’t act now, water will cause more and more damage in the structure, corroding the steel reinforcement bars and causing damage to the concrete itself. Leaving it alone is not really an option: and would mean bigger and more disruptive roadworks in future.’
Highways England said summer closures have been timed for when the roads are quietest.
It added that Birmingham City Council has been invited to use the road closures to complete essential maintenance tasks that would otherwise need roadworks in future, and has agreed to pause its roadworks on diversions and alternate routes when the closures are in place.