The Bricklayers Arms flyover will be closed to traffic for six weeks this summer, Transport for London has announced.
The works include the replacement and waterproofing of the bridge deck expansion joints across the flyover as well as the installation of new drainage.
Works began on 18 July and will be completed by the end of September.
Transport for London says that this work will extend the life of the flyover, helping to prevent deterioration of the structure and reduce future maintenance for many years to come.
The main flyover will be closed to traffic from Saturday 23 July until Saturday 3 September.
The closure has been programmed to coincide with the school summer holidays. During this time traffic will be diverted around the Bricklayers Arms roundabout.
TfL says that the work was originally due to last 15 weeks but by using innovative materials and working methods – such as fast-curing concrete – it has been able to reduce the closure programme to six weeks.
"This essential work to refurbish and resurface the Bricklayers Arms flyover is vital to ensure that the structure can remain open to traffic," says Dana Skelley, director of roads at TfL.
"During this work, we will ensure that disruption for road users and local residents is kept to a minimum and will be working to complete these works as quickly as possible."
Both Labour and Liberal Democrat politicians in Southwark would prefer to see the flyover eliminated rather than refurbished. Before last year's elections Cllr Peter John, now leader of the council, told the SE1 website that removing the flyover "will certainly be on our transport agenda".