WORK on the M5 Oldbury viaduct is set to reach a key milestone following the completion of more than 5,000 repairs to the structure.

The project involves concrete repairs and waterproofing along a two-mile section of the ageing stretch of road.

Work on the southbound carriageway, between junctions 1 and 2, is approaching completion and in the coming weeks the entire operation, involving more than 500 workers, transfers to the northbound carriageway.

Already more than 5,000 separate repairs have been carried out on the southbound carriageway, 3,500 more than anticipated.

The majority of work is scheduled to continue until autumn 2018, with other work continuing into spring 2019.

Highways England senior project manager Zbigniew Twarowski said: “The scale of this project is vast and has involved a large number of repairs. On top of that we’ve had one of the harshest winters in years, which has added to the challenges.

”We will not know the full extent of the repairs needed on the northbound carriageway until work there is under way.

“We appreciate the level of disruption this project involves and I’d like to thank motorists, businesses and residents for their patience. Meanwhile, our teams are working as hard as they can to get the job done.”

At more than £100 million, M5 Oldbury is believed to be the largest concrete repair project, by value, ever carried out in Britain, but much of the work takes place underneath the viaduct and so workers cannot always be seen on the surface itself.

To keep the motorway open, a contraflow system is in place with traffic currently using the northbound carriageway with two lanes operating in each direction, along with a 30mph speed limit. Traffic is anticipated to move to the southbound carriageway in June.

Slip roads at junctions 1 and 2 are being kept open to ease effects on the local network. However, as part of the work, a number of closures of the southbound off-slip at junction 2 are planned.

The first closure will start this weekend from 8pm Friday, May 11 to 6am Monday, May 14. The last closure will be on Friday, June 29 to Monday, July 2. During the Spring Bank Holiday weekend, the slip road will close at 10pm on Friday, May 25 and open at 6am on Tuesday, May 25.

Traffic wishing to exit at M5 junction 2 southbound will be diverted to junction 3 and then back to junction 2 where drivers will be able to exit the M5 via the northbound off-slip.