The crew used a bucket, stones and moss to make an impromptu nest after taking advice from the council's ecologist.
Jenny Watkins from Gloucestershire Highways told the BBC: "Two hours later the bucket was full of bees, and they seemed to be using it as a new nest."
The bucket has been left near the old nest at Ablington Bridge, near Bibury.
Gary Kennison, ecologist for Gloucestershire County Council, said: "It's definitely a nest of bumble bees but we don't know which species yet.
"We've taken photographs and will send them to the biological records centre near Standish, to confirm what we have found.
"This is important as it could be a scarce species that's not been recorded in the county before, or it might even be the first time such bumble bees have been found in a bridge or structure like it."
Murfreesboro’s Broad St. bridge repair is completeNot drowning but dozing - PHOTO