The price tag for upgrades to parts of the A47 could rise significantly from earlier estimates, highways bosses have revealed.

More detailed plans to upgrade the trunk road, which are likely to form part of the Department for Transport bid for roads cash from the Chancellor in the Autumn Statement, suggest the cost of dualling the road from North Tuddenham to Easton could be between £100m to £155m, compared to the £75m outlined in a business case drawn up by the A47 Alliance.

The cost of dualling the road from Blofield to Burlingham could be between £54m and £80m, compared to £40m in its original business plan.

The earlier estimates were drawn up by consultants Mouchel, based on what other recently delivered Highways Agency schemes had cost, reflecting what the scheme would have cost in 2010. But the Highways Agency has looked at the likely price of building the road in 2020, also taking into account the risks.

The Department for Transport looks set to put forward a £504m wishlist to the Treasury which will also include:

The duallilng of the A47 between Wansford and Sutton in Cambridgeshire (costing between £66m and £94m)

An upgrade to the A47/A141 Guyhirn Junction (£11m to £16.5m)

An upgrade to the A47/A11 Thickthorn Roundabout (£67m to £103m)

Safety measures for the A47 Acle Straight safety measures

An upgrade to the A47/A12 Vauxhall roundabout junction, Great Yarmouth, (£19.6m to £28.8m)

A package of improvements to A12 junctions, including Gapton Hall (£2.7m to £4m) and Harfreys (£8m to £10m) roundabouts and around James Paget (£382,000 and £566,000).

The new figures were disclosed at a private meeting for 'stakeholders' attended by council officials, MP researchers and rural bodies.

Ian Shepherd, from Norfolk's Campaign to Protect Rural England, said: 'My impression was that all points of view were being listened to and heard by the DfT and Highways Agency who made the presentations. As a member of an environmental NGO in Norfolk, and for that matter as a local resident, this was a welcome change given the experience of the past five years with the progression of the Joint Core Strategy for Greater Norwich, and the Northern Distributor Road.'

He welcomed moves to improve the cost estimates and identify the cost implications of specific problems that might be encountered.

'Costly 'over-runs' affect not only other transport options, but will compete with many other services that are in public demand,' he added.

Toby Coke, Chairman of Norfolk County Council's Environment, Development and Transport Committee, urged the government to commit to funding the schemes in the Autumn Statement and to instruct the Highways Agency to get on with the design work to allow them to be built as soon as possible.

'We desperately need a firm commitment from government on the dualling of the whole A47, so we still have a long way to go before we have the infrastructure the county deserves.'

He has also raised concerns that there is so little 'on offer' around King's Lynn, which he said was one of Norfolk's main centres for growth.

A Department for Transport spokesperson said: 'We are discussing a range of potential options for improving the A47 with interested parties to understand their views. Part of this process involves estimating outline costs for potential options. No investment decisions have been made as this is work in progress and when completed, the study outcomes will inform the Government's 2014 Autumn Statement.'

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