Thieves have stolen more than £20,000 of plant from a road improvement job in Tewkesbury.
The raiders hit Britannia Construction's site on the High Street where the firm is working on a £250,000 road safety scheme for Gloucestershire County Council.
Two one-tonne mini-dumpers, each worth £10,000, have been stolen and a power pack for a hydraulic breaker, worth £400, has also been swiped.
Vandals have also broken the window of a fork-lift truck.
The county council's local highways manager, Richard Waters, told the Gloucestershire Echo: "It is disappointing that our contractor has suffered these thefts and acts of vandalism, but nevertheless they have been making excellent progress in delivering this scheme."
He added that the work is due to be completed by early May, with the road due to be resurfaced early in June.
The cost of the thefts and vandalism will be covered by the contractor's insurance, so the county council will not be liable.