Rural Puhoi residents have won the backing of two local authorities in their fight to retain access to the Northern Motorway and proposed extensions.

Plans issued in June by the NZ Transport Agency for consultation provided for a new motorway from the Puhoi tunnels to Wellsford, with ramps for Warkworth and Wellsford but not for Puhoi village and Mahurangi West.

Resident Allan MacDonald said yesterday that local authorities at first went along with the agency's thinking of not having a direct link for Puhoi to a "road of national significance", which is to be built off the line of the existing State Highway 1.

A reason given was that the interchange would serve only a small population of 1500 in a non-growth area on Rodney District Council and Auckland Regional Council planning policy documents.

But he said people had already moved to the area because the Puhoi tunnels brought them State Highway 1 access.

Having persuaded Rodney District Council there was a strong case for a link to the new highway, Puhoi residents went to the ARC transport and urban committee on Wednesday.

"We showed urban development simply cannot happen here because of the hilly topography and unstable land and the ARC recognises the impact on residents of losing motorway access," he said.

"The Transport Agency's reasoning has been found to be incorrect, the local authorities support access and the agency should reconsider its position.

"It is a Government decision whether to pay for access or not."

The ARC transport committee chairwoman, Christine Rose, said the ARC remained unconvinced of the need for an offline motorway from the Puhoi tunnels to Wellsford.

Work to improve safety and reliability of the existing State Highway 1 was the immediate priority.

However, if the agency continued plans for the new motorway, then the ARC strongly supported keeping access to the communities of Puhoi, Mahurangi and the wider Rodney district.

The ARC called on the agency to assess the effect of not giving Puhoi ramps on the wider road network, including in Orewa, which has created a boulevard through the town since the tunnels opened.

Agency regional director Wayne McDonald said it was in the initial phase of consulting on design principles for the highway.

He reassured motorists that emergency services would be able to access the tunnels from North Rodney when the motorway is built.