NZTA wants Wellington highway changes in one fell swoop

Monday, 1 December 2025

NZTA has provided this image to indicate what State Highway 1 between downtown Wellington and the airport will look like if a second tunnel under Mt Victoria is built.

Two new Wellington tunnels and massive roading changes ‒ especially around the Basin Reserve ‒ will be done in one big hit while the Petone to Grenada link road will get the same treatment, if NZTA planners get their way.

Waka Kotahi NZ has released its extensively redacted investment case for the road changes it has planned for the capital. Pages headed “key risks”, “cost and contingency” and details about potential road tolling have been hidden though the papers do say tolling is feasible.

It would increase revenue but drop the cost-benefit ratio of the project to mean ‒ even under the best-case scenario ‒ the benefits of the project would only match the cost and could be worse.

The investment case makes a strong case to do the entire project in one hit rather than a series of works. It says a sequential programme prolonged disruption while a concurrent programme minimised “overall” traffic disruption, had better value for money, and reduced uncertainty.

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Transport Minister Chris Bishop said it was up to NZTA how it got the job done “but I am supportive of getting on with the job and seeing it completed”.

The Government supported greater use of road tolling, he said.

“The investment case supported tolling the SH1 Wellington improvements to help fund the construction and maintenance of the road. I expect to receive advice from NZTA on tolling the SH1 Wellington Improvements in due course,” he said.

The papers say a concurrent programme recognised the “specialist nature of the tunnels taking advantage of shared design and construction resources helping to maximise project value outcomes while minimising cost”.

A public-private partnership (PPP) was not desirable, according to the report.

“The project's constrained network size makes it costly and unattractive, and its likely timeline make return on investment less appealing.

“Additionally, the financing and management costs associated with a PPP model do not provide sufficient value.”

A regional road user charge or fuel levy was “worth considering”, they noted.

The project, costing $2.9 billion to $3.8b, is for second Mount Victoria and Terrace tunnels, completely changing roads around the Basin Reserve, making Vivian St three lanes, and big changes in Hataitai including a new overpass.

Rongotai MP and Green transport spokesperson Julie Anne Genter said the investment case seemed sloppy and rushed but, the positive aspect was that work couldn’t start until 2028 or later.

NZTA had not been fully transparent with the public about how disruptive the works would be, she said. The papers noted it had a “high” cost and “low efficiency”.

Wellington mayor Andrew Little said the project would be disruptive whether it was phased or done as one piece of work. “What’s most important is that the design works well.”

It was also important that people gave Waka Kotahi feedback, which ends on December 14.

Labour Wellington Bays candidate Craig Renney was not opposed to the plans but said it needed to be clear the Government was getting value for money. There was a suggestion that some funding could come from Wellington ratepayers, he said.

“It is not clear that the consequence of doing all this at once, in terms of construction [disruption] to Wellington have been fully considered in this analysis,” he said.

The investment case for the 5.5km Petone to Grenada four-lane, median separated highway was released on Friday showing a better benefit-cost ratio than the inner city plans.

“The project links two state highways together and is, therefore, difficult to stage; the full connection delivers the project outcomes,” the papers said. It also warned the road would bring more traffic and delays to Lower Hutt’s roads.

The papers offered a first glimpse of the corresponding Cross-Valley Link, which would connect Seaview and State Highway 2 using Wakefield St and White Line West, joined together by a new bridge over Te Awa Kairangi Hutt River.

However, construction won’t begin on that project until the Petone to Grenada road is built.

Lower Hutt mayor Ken Laban believed the importance of the roads warranted any disruptions. “I’m sure we’ll do our best to mitigate that.”