The funding for £40m traffic measures, including a road that would connect the A10 to the A47, was discussed at a hearing into the future of housing development in west Norfolk.
The proposed relief road would link the south of West Winch to the A47 at North Runcton to relieve traffic using the A10 up to the Hardwick Roundabout in King's Lynn.
But it has emerged that part of the funds will need to come from housing developments proposed for West Winch, which have not yet been given the go-ahead.
'There will also be a series of funds from third parties,' David Maddox told the hearing, 'and the local enterprise partnership will also be included.' He was speaking at a session dedicated to the allocation of sites for 1,600 homes in West Winch and represented Zurich Assurance Ltd, the owners of the controversial Gravel Hill site.
Councillors for West Norfolk Council reinstated the Gravel Hill site into future housing plans last week, despite it being previously withdrawn following fierce opposition.
As well as the relief road, traffic calming measures along the A10, improvements to the Hardwick Roundabout, and dualling of the A47 were also discussed.
But the plan which would outline infrastructure development for West Winch and North Runcton was not yet available for participants.
David Hogger, the government-appointed planning inspector overseeing the process, said: 'We need some clarity on the approach [for infrastructure]. It is not quite clear to me how various elements will come together and how they will be done.'
Meanwhile Richard Morrish, who is working on the neighbourhood plan for West Winch, added that clarity was needed in the process of allocating development sites and stressed that localised flooding at Gravel Hill is something residents 'are very concerned about'.
It also emerged that the areas in West Winch and North Runcton could be protected due to mineral safeguarding and they could be of national importance for silica sands.
Richard Drake, from the Mineral Planning Authority at Norfolk County Council, said: 'It is only one of two locations in the county where this grade of mineral is available.'
How has local development affected you? Email louise.hepburn@archant.co.uk
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