A traffic engineer is questioning whether a planned $1.7billion Puhoi-Wellsford extension on Auckland's Northern Motorway makes economic sense for Northland.

Whangarei's Dean Scanlen, from the firm Engineering Outcomes, has looked at plans to extend the motorway, which currently ends near State Highway One's Puhoi turnoff.

The project is one of the Government's Roads of National Significance and is touted as essential for Northland's future growth, but Mr Scanlen told a Far North District Council meeting on Thursday he was unconvinced. "I'm not necessarily against the project, but I'm concerned that the economics aren't that flash."

He also doubted the NZ Transport Agency had properly considered the alternatives.


Mr Scanlen initially voiced his doubts in a letter to the Advocate. The Whangarei Economic Development Group invited him to make a presentation; Mayor Wayne Brown heard it and asked him to speak at a council meeting.

Mr Scanlen said the motorway to Warkworth was due to be completed by 2019 followed by a four-lane expressway to Te Hana, on Northland's southern border, by 2030. However, the NZTA had not considered options involving less than four lanes.

Northland would benefit more if the money were spent on re-alignments, bypasses, intersection upgrades and passing lanes on its highways. With freight growing faster than car traffic serious consideration should also be given to upgrading rail and building the Marsden Pt link.

Mr Scanlen's suggestions for fixing the slowest sections of SH1 included a tunnel through Schedewys Hill, south of Warkworth; bypasses around Warkworth and Wellsford, and a new route at the Brynderwyns combining a 2km tunnel and 5.4km of new road. A bypass around Kawakawa and Moerewa was another possibility.

Flooding near Kawakawa, Moerewa, Kaeo, Rangiahua, Kaitaia and Te Kao was another problem not addressed by the Government's plans for SH1. The problem might not register from an economic point of view but the NZTA had a "moral obligation" to address it.

Mr Scanlen said the decision to push the Puhoi-to-Wellsford project was political rather than economic, so any challenge had to be mounted at a political level - and would have to be backed up by a rigorous investigation of Northland's transport options.

Mr Brown said he had changed his views on the Government's Roads of National Significance strategy and now saw it made sense.

However, he questioned the logic of building a four-lane motorway to Wellsford when the slowest part of the Auckland-Northland drive was crossing the Brynderwyns. The same amount of money would allow SH1 to be widened to three lanes all the way to the Bay of Islands.


The council will consider funding a more detailed study of transport options, possibly with Northland Inc.