DRIVERS using the M5 must prepare themselves for at least six months more congestion misery after it was confirmed the two-year-long Oldbury Viaduct works will not finish until the autumn.

The works – involving repairs and waterproofing to the viaduct between junctions 1 and 2 – have caused daily delays for Black Country and Worcestershire motorway users since they began in April 2017, reducing the number of lanes.

Highways England last year admitted the works were running six months behind schedule, blaming the severe winter of 2017 and the unusually hot summer of 2018 for the delays.

They hoped to have the 1.8mile section of the M5 back up and running by this spring – but a new Sandwell Borough Council report says the work will not finish until the autumn.

The report says: “The project remains on track for completion in the Autumn of 2019.

“Good progress is being made on the repairs to the northbound carriageway and time is being saved based on the some of the lessons learnt from the southbound deck.”

Work on the southbound carriageway was completed last September.

The latest update on the Highways England website listed the reasons for the delays.

It said: “The scheme is very complex and at times causes a great deal of disruption for motorists, which we regret.

“Unfortunately, the southbound work has taken longer than anticipated to complete as:

• last winter was one of the most severe in years, with freezing temperatures and snow delaying our concrete repair operations and causing issues for workforce safety

• the prolonged heatwave disrupted the operation to lay waterproofing material. This sits directly under the surfacing and is required to protect the repaired deck from deterioration from water and road salt. Waterproofing cannot be applied when the deck temperature exceeds around 30C. The surface temperature on the viaduct had been around 40C, therefore the waterproofing material could only be applied overnight instead of 24/7, considerably reducing production rates.”

The £100m scheme is the largest concrete repair project ever undertaken in the UK.

A Highways England spokesperson said: “The repair work on the M5 Oldbury viaduct is essential and we remain committed to completing this work as quickly and as safely as possible, while doing all we can to reduce disruption to motorists, businesses and residents.

“Due to the complex nature of the scheme there are further repairs that require attention.

“We aim to have made enough progress to remove the contraflow in the next few months, with traffic restrictions removed later this year and we’d like to thank motorists for their continued patience while this essential work takes place.”

They added: “The work we’re doing to repair the M5 Oldbury viaduct is essential if drivers are to continue using it for years to come.

“It is complex and we’re finding further safety critical repairs on the northbound carriageway that require work.

“We’ve completed all the concrete repairs in the hard shoulder and lane 1, between junctions 1 and 2 northbound.

“The southbound carriageway work took longer than anticipated to complete. We were only able to fully assess the condition of the southbound carriageway once the work had started and we had got under the surface of the road.

“We found a higher number of individual repairs were required than we could have anticipated – more than 8,000, which is around 4,500 more than anticipated.

“We’ve found the northbound side of the carriageway to be in a similar condition to the southbound before repair work started there.”