Unforeseen delays means that improvement work to the Centenary way flyover will now not be completed until the New Year.
Lancashire County Council chiefs admitted that the concrete deck in the structure is much worse than expected, adding eight weeks to the work.
Concrete deck in a much worse condition than predicted...David Leung, Lancashire County Council design and construction manager
The planned completion date has now changed from December 18th to February 12th next year.
David Leung, Lancashire County Council design and construction manager, said: “This major refurbishment of the Centenary Way Viaduct is vital to extend the life of the bridge, which was built in 1967. The A682 is a key route from the M65 and vital to the local economy, particularly as a route for HGVs to a number of development sites.
“The project involves replacing and renewing a number of parts of the structure, including replacing the bearings and joints, repairing and waterproofing the concrete deck, and resurfacing.
“We’re currently working on the northern deck with the majority of the works progressing as planned and according to schedule. However we have found the concrete deck to be in a much worse condition than predicted by investigations carried out during the planning stages before work started.
“This means we’ve had to carry out a significant amount of extra repairs to restore the deck. We expect to finish work on the northern deck, and move over to the southern deck in November.
“We’re sorry for the added inconvenience this will cause, but our priority must be to make sure the repairs made stand the test of time and ensure that it will be many years before work of this scale is needed again.”