Work stopped on a bridge over the River Lune when engineers found a nest of birds.
Blue tits and jackdaws were found under the east cycleway bridge over the Crook O’Lune during restoration and demolition work.
Engineers were back on site on Monday after the nesting birds moved on.
“This has set us back a few weeks but we are looking to find ways to recoup some of the lost time to minimise any inconvenience,” said Kim Whalley, Lancashire County Council’s senior bridge engineer.
The bridge is a listed structure, which links Caton with the River Lune Millennium Park. It was originally closed for safety reasons in March 2011.