Campaigners are today calling for county councillors not to agree to plug a funding gap for the controversial Norwich Northern Distributor Road - but to only build the road as far as the A140.

A key decision over how to pay for the £178.5m road is to be taken again today – following a legal challenge.

The Wensum Valley Alliance launched legal proceedings over a decision made by the council to pay for the road, which would stretch from the A47 at Postwick to the A1067 Fakenham Road.

Andrew Cawdron, parish councillor in Great and Little Plumstead, launched a bid for a judicial review on behalf of the alliance.

He claims a council meeting – where councillors agreed to put forward £10m towards a £30m funding gap after the cost of the road escalated – was unlawful.

At that meeting, council officers admitted an error had been made in its benchmarking over whether the construction inflation costs were reasonable.

The council is not contesting the legal challenge, but will today make a decision again, with officers saying the full and accurate information is now available.

Officers are recommending that councillors agree to plug the funding gap, with £10.4m from the highways budget. That figure is higher than the £9.9m agreed at the last meeting. Officers say £500,000 more is needed as a contingency in case the delay in starting work has increased construction costs.

But Andrew Boswell, Green county councillor, hopes councillors will instead agree an amendment to the proposal, to save £45m by only building the road from Postwick to the A140 at Norwich International Airport.

He said: 'There is still no convincing reason for the cost increase of £30m when supply chain costs have actually decreased slightly over the same time period. The recent hike exposes the council and the taxpayer to costs of up to £91m. To pay for it, the council will be degrading the highways maintenance until at least 2020, and servicing a loan at around £2.2m annually. The loss of many community infrastructure projects will be collateral damage.'

The Wensum Valley Alliance has written to all 84 county councillors urging them to back Mr Boswell's amendment.

Jenn Parkhouse, from Norwich Friends of the Earth said: 'This council is risking public finances – the cost of up to £91m is too much for Norfolk taxpayers. The Government has never supported building the NDR beyond the airport, and it

is local taxpayers who fund this section entirely.' But council officers, in their report argue that would require a fundamental re-assessment of the scheme's effects and benefits, a fresh public inquiry could be needed and funding could be put at risk.

Officers say, if councillors agree to the funding, then the work will start later this month.

• What do you think of the NDR? Write, giving full contact details, to Letters Editor, Prospect House, Rouen Road, Norwich NR1 1RE or email edpletters@archant.co.uk