The cost of the controversial Norwich northern distributor road looks set to soar to �141.5m - after county councillors agreed to push ahead with plans for it to be dualled all the way to the A1067.

And that means Norfolk County Council will have to find an extra �40m to pay for just over four miles of the controversial road, because the government has not agreed to fund the NDR beyond the A140.

The Department for Transport agreed in December to provide �86.5m for the road, but only for the 12.5km section between Postwick on the A47 and the A140 near Norwich International Airport.

However, at a Norfolk County Council meeting yesterday, councillors agreed that the planning application which will be submitted for the road later this year should be for a 19.5km dual carriageway road continuing beyond the A140 to the A1067 Fakenham Road.

And they agreed that, rather than building to the A140 and then looking to extend to the A1067 at a later date, it would make sense to seek planning permission for the whole project at once.

That will add millions of pounds to the cost of the project, with the county council already needing to top up the government funding for the rest of the road by �13.3m.

The council hopes to recoup some of the extra cost through a new 'tax' on housebuilding - known as the community infrastructure levy (CIL).

The Greater Norwich Development Partnership (GNDP) - made up of Norwich, Broadland and South Norfolk councils - has agreed in principle to provide up to �40m towards the road from that levy.

Tim East, the Liberal Democrat spokesman for planning and transportation, said: 'My view is that if we are going to support the NDR, then we should dual it all the way through. It cannot be dualled from Postwick to the airport and then single carriageway to Fakenham Road. That's a crazy idea.'

He pointed to the fact the bypass at Attleborough, originally single carriageway, had undergone costly dualling years after it was built.

Tony Adams, Conservative councillor for Drayton and Horsford, said: 'I think we have learned our lessons when it comes to dualling and if we leave it for 10 years then it will cost us more in the long run. I am proposing that it is a single project and that is a dual carriageway.'

That is the recommendation which will go to cabinet. If cabinet agrees, a planning application will be submitted in the autumn, followed by a series of public exhibitions next year.

The planning application will be considered next spring, which will be followed by a public inquiry next summer.

Pending further approval, work could start on the road in spring 2015, with the road opening two years later.

However, speaking after the meeting, Green county councillor Andrew Boswell, warned: 'Conservative councillors chose the most expensive and risky option of going for the full three quarter NDR now at a cost of �53m on top of government funding.

'The council will have to borrow at least �13m and possibly more if the GNDP councils can't agree to CIL spending priorities. Council taxpayers will be paying interest on this road to nowhere for a long time.'

Meanwhile, Norfolk County Council has organised public information exhibitions this Friday and Saturday to show plans for the �19m improvement of the A47 Postwick junction, seen as the gateway to the NDR.

The exhibitions support the re-advertisement of the draft slip road and side road orders for the scheme.

The county council says the current junction will not be able to cope with future residential and business expansion in the area.

The draft orders are available to view at Norfolk County Council and Broadland District Council offices until Friday, April 13.

The exhibitions will be held at Broadland District Council's office in Yarmouth Road, Thorpe St Andrew.

They will be open to the public on Friday from midday to 7.30pm and on Saturday from 9am to midday.

County council engineers and Highways Agency staff will be available at the exhibitions to help explain the proposals.

dan.grimmer@archant.co.uk