GUIDED busway contractor BAM Nuttall, which is facing a claim for £60million from Cambridgeshire County Council over the project has lodged a £43m counterclaim.

According to the respected professional magazine New Civil Engineer, documents filed at the Technology and Construction Court show that the contractor blames consultant Atkins, the council’s project manager, for much of the delay to the 25km longest busway in the world – which has proved so successful since it opened last August that principal operator Stagecoach has had to order extra buses.

The county council has spent £152m delivering the busway. Under the terms of the construction contract BAM bid a target price for the works. During construction the contract required the council to pay the actual cost of the work, but at the end of the construction period the difference between the actual cost and the final target cost is split between the parties in accordance with a formula set in the contract.

The county says its share of the cost overrun amounted to no more than £5m, and it wants the rest of the money back.

But NCE says the documents lodged by BAM say that the failings of the project manager were “serious and numerous” and identify a change of project manager as a particular problem.

Bob Menzies, the county council’s head of infrastructure delivery, said: “We are pleased that after a number of delays BAM have provided their defence and counterclaim to the legal claim submitted by Cambridgeshire County Council in August of last year.

“BAM’s documents will now be reviewed in detail by the council’s legal team. The council has obtained extensive advice on the busway contract and remains confident of its position.

“It would be inappropriate for us to make any further comment until we have reviewed BAM’s defence and counterclaim and prepared and provided our formal response, which will be submitted to the court in due course.”

A spokesman for BAM said the company had nothing to add to the documents lodged with the court.

In an unrelated move, Liberal Democrats on the council have accused the authority of failing to act on road safety fears on the Cambridge stretch of the busway.