Work begins on finding best route for $2b highway

Early community consultations are expected on route preferences for a new "road of national significance" costing up to $2 billion between Puhoi and the north of Wellsford.

That follows the Transport Agency's awarding last week of a contract worth to $12 million for route investigation work on a proposed 38km link, entailing a four-lane extension of the Northern Gateway toll motorway to Warkworth and a dual-carriage expressway beyond that.

The investigation, by engineering and environmental specialists Sinclair Knight Mertz, is expected to take 15 months, but agency acting regional director Tommy Parker said he would be "disappointed if we are not talking about [route] options before about the middle of the year".

Mr Parker said $6 million of the investigation contract would be a guaranteed payment, leaving the remaining amount conditional on performance.

He was confident the consultants would "help us deliver a high-quality solution that will help reduce congestion, improve safety and encourage economic growth".

Sinclair Knight Mertz would be responsible for community consultation.

A route roughly following the existing mainly two-lane State Highway One and bypassing Warkworth and Wellsford has been pencilled into a summary statement which the Transport Agency compiled for the project in January as one of the Government's seven designated roads of national significance.

Mr Parker said it followed "the path of least resistance" and, although the final route remained subject to new ideas from the consultants, the geology and topography was extremely challenging.

Transport Minister Steven Joyce said although there appeared to be a good chance of completing the motorway to Warkworth within 10 years, it would be more difficult to finish the expressway to Wellsford in that time.

"However, that remains the Transport Agency's goal," he said.

"The Puhoi to Wellsford corridor has been identified as one of our most essential state highway routes to reduce congestion, improve safety and support economic growth in the Auckland and Northland regions."

That view is not shared by the Auckland Regional Transport Committee, which considers it a low priority.

Auckland Regional Council chairman Mike Lee has derided the proposal as "a holiday highway" for Aucklanders rushing to beach resorts east of Warkworth and the Green Party says estimated economic returns of 80c to $1.10c for every $1 to be spent on it do not stack up.

But the Transport Agency says the figures were calculated by discounting the benefits at a standard 8 per cent each year after the road opens, a rate it sees as more appropriate to short-term projects.

It says if a 4 per cent discount rate could be used to reflect the longevity of the road, the economic returns could rise to $2 for every $1 spent.

Although the Transport Agency ear-marked almost $2.2 billion for the project in its latest 10-year programme, a more recent cost forecast has brought that back to an estimated $1.53 billion to $2.04 billion.