The Aberdeen Roads consortium has now completed repair works to fix defects to a bridge structure over the River Don, which was holding up the scheme.

This marks the conclusion of physical works on the bypass, which is already 85% open, and the project had been due to finally open at the end of January. But despite this the final unopened section remains closed to traffic.

Michael Matheson explained: “The road can only be fully opened once ministers receive the necessary assurances about the longer term impact of the remedial work and the changed costs of future maintenance.” These assurances, according to Transport Scotland, have not been forthcoming.

It is thought that costs on the project may have risen by up to £350M from the original £745M budget owing to the repair work on the Don Crossing as well as the impact of poor weather conditions.

Transport Scotland said it is not unusual for claims for additional sums to be raised by a contractor on large infrastructure projects “However, not all claims have merit,” the authority added. “It would therefore be wrong to assume the contractor’s total cost, whatever that turns out to be, is automatically borne by the public purse.

“Aberdeen Roads spent two years bidding for the project and went into it with eyes wide open.”

A spokesman for the Aberdeen Roads consortium said that, due to contractual arrangements they are unable to comment on the project.

(Photograph: Transport Scotland)