The way the budget for the Norwich Northern Distributor Road spiralled by £56.5m should be investigated by an external auditor, councillors decided.

Eastern Daily Press: Tom McCabe,, executive director of community and environmental services. Picture by SIMON FINLAY.Tom McCabe,, executive director of community and environmental services. Picture by SIMON FINLAY.

The budget for the 12.5-mile road, also known as the Broadland Northway, went up from the £148.5m estimated in 2013 to the current prediction of £205m.

Norfolk County Council bosses admit lessons need to be learned about the way the contract was awarded and managed.

And the scheme came under the spotlight at a meeting of the council's scrutiny committee on Tuesday.

Readers of this newspaper were invited to suggest questions to be posed at the committee. Issues raised included oversight of the contract, the design of the roundabouts and the loss of trees along the route.

Officers explained how contractor Balfour Beatty had submitted more than 1,300 compensation events - requests for costs above and beyond that of the original contract.

Officers said those, along with issues with Network Rail, diverting utilities, redesigns and poor weather, had pushed up the price of the scheme.

They said they had tried to keep those costs down and negotiated hard.

Tom McCabe, the council's director of community and environmental services, said: "It was a hard, hard, slog trying to keep the cost down right the way up to the last few months. We were just trying to arm wrestle as good a price as we could out of it. The cost took the sheen off it for me, personally."

When asked what profit the contractors had ended up making, Mr McCabe said he did not know.

But he added: "What I will say is that, within the last six months of discussions with my opposite number, I'd like to think they were not happy. It certainly wasn't a question of them slipping away with satchels of silver and then disappearing off."

Mr McCabe was not able to give an answer when asked whether the cost of the road and interest on borrowing for it came to £230m.

Officers said some changes would be made to roundabouts in the months ahead. At the end of the meeting, two recommendations to cabinet were made.

On the casting vote of Labour chairman Steve Morphew after a five/five split, one was to ask an external auditor to investigate.

The other was to back the work to get a Western Link for the NDR.