Auckland Mayor Wayne Brown has questioned the multibillion-dollar costs of the Northland Corridor, saying a cheaper alternative is needed sooner.

But Transport Minister Chris Bishop said it was a long-term project with national benefits, while NZ Transport Agency (NZTA) has committed to driving costs down.

The 100km corridor, also known as the Northland Expressway, is made up of three Roads of National Significance (Rons), with work due to start in late 2026 on the first part, from Warkworth to Te Hana.

The NZTA board has approved the investment case for the other two parts: Te Hana to Port Marsden Highway, including an alternative to the Brynderwyn Hills, and Port Marsden Highway to Whangārei.

The Government is funding $187 million for design, consenting, route protection and property acquisition along this 75km stretch, with priority given to the Brynderwyn Hills alternative.

It is expected to cost between $15.3 billion and $18.3b, including contingency, making it one of New Zealand’s most expensive infrastructure projects.

Tolling has already been signalled for the corridor, with NZTA saying there will be consultation on tolls for both building and maintenance.

But Brown, who is also a former Far North mayor, has questioned the high cost, initially asking if it was a mistake.

“Northland needs a much improved and more resilient connection to Auckland, but this seems too expensive,” he said.

“The quoted cost of $15.3b to $18.3b means this road could cost $200m to $240m per kilometre, or $200,000 to $240,000 per metre!

Auckland Mayor Wayne Brown says while a more resilient road is needed over the Brynderwyn Hills, the cost of up to $18.3 billion for Whangārei to Te Hana is too expensive. Photo / Waka Kotahi. Inset / NZME

“This is an extraordinary cost.”

The “ridiculously expensive” Pūhoi to Warkworth highway cost a third of this price, at $73m per kilometre, Brown said.

“We need to look at options that are affordable; the country can’t afford to build transport projects that are this expensive.”

He also criticised the central Government’s $187m funding to design and secure the route, saying it will not build a single metre of road and likely be spent on consultants.

Brown said the NZTA has only approved an investment case, and there was still time to make changes.

“NZTA need to give their designers and engineers a hurry up and tell them to come back with a cheaper option, that can deliver benefits for Northland sooner.”

The Northland Corridor includes three Roads of National Significance.

But Bishop said the Northland Corridor will provide nationally significant benefits while it is built in stages over several years.

“We’ve been upfront about the fact it is a complex project and will take a long time. The Waikato Expressway is still being built more than 20 years after it started.”

The new route will be safer, more resilient and reduce travel times, while unlocking major economic opportunities for Northland, the minister said.

“Regular slips have cut off communities, highlighting the need for this new road.”

An NZIER report in 2024 found the Northland Expressway would benefit Northland’s economy by $2.1b a year and increase national GDP by $1.2b a year.

NZTA said in a statement the $15.3b to $18.3b investment includes design, consent, property acquisition, construction, escalation, contingency and funding risk.

It is a conservative estimate, and NZTA will continue working to find efficiencies and drive costs down.

Transport Minister Chris Bishop says the Northland Corridor will bring national benefits and is part of a long-term infrastructure plan for the country. Photo / NZME

The Northland Corridor benefits include improved travel times and reliability, economic growth, improved safety and a benefit of $1.40 for every dollar spent, NZTA said.

Bishop said tolls are recommended to support both building and maintenance on the Te Hana to Whangārei section.

“NZTA will seek approval from the Minister of Transport, currently me, for public consultation on tolling.”

Bishop also defended the $187m initial costs, saying investigations, property acquisition and consents are needed before building begins.

“Securing land now provides planning certainty and prepares for future construction when funding becomes available.”

The coalition Government is committed to developing a long-term pipeline of transport investment, as asked for by the sector and the public, Bishop said.

This involves route protection, consents and designations, so building can begin quickly as funding becomes available, he said.

Stage one of the Northland Expressway is currently in procurement, with construction set to begin next year, Bishop said.

Denise Piper is a news reporter for the Northern Advocate, focusing on health and business. She has more than 20 years in journalism and is passionate about covering stories that make a difference.