EnterpriseMouchel is overseeing the £5m contract as MAC contractor in the region.

Work started in February on the bridges at junction 9 and was due to be completed in September.

But that date has now been pushed back to January 2014.

Steve Cobb, Highways Agency Structures Manager said: “Work to replace the bridge piers is progressing; however we have found a number of additional tasks are required.

“We have carefully considered how best to complete this extra work, and concluded that the most efficient way for all is to carry on, rather than completing this phase and then returning at a later date.

“As a result, it is currently anticipated that construction work will now be completed by the end of January 2014 instead of September 2013.”

The agency said that as work has progressed the construction team have discovered that the original plans of the piers do not match the situation on the ground, meaning extra work is required to complete the scheme.

Also, detailed assessments of the beams have shown that more extensive repairs than originally anticipated are required.