Transmission Gully faces major summer rebuilds as costs, legal wrangles remain unclear

Thursday, 28 August 2025

A timelapse video of driving the $1.25 billion Transmission Gully from Paekākāriki to Linden on the first day of opening.

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Just three years after its grand opening, the $1.25 billion Transmission Gully motorway is set for major resurfacing and rebuild works – but Waka Kotahi cannot yet say what the repairs will cost, or who will pay.

The transport agency confirmed about 20 lane kilometres of State Highway 1 north of Porirua will undergo resurfacing, drainage upgrades, and rebuilds during the summer maintenance season, from October to March.

Work will affect both lanes near the Kenepuru, Waitangirua and SH58 interchanges, as well as around the Battle Hill area.

The agency said water had seeped into the road base and damaged the pavement, making drainage improvements critical.

“The work programme is still being finalised and the specific times for when and where work will be carried out are still to be confirmed. We will be sharing more information with the public about this over the coming weeks,” Mark Owen, regional manager for Lower North Island/Top of the South, said.

“The current plans are to complete resurfacing work north of the Kenepuru Interchange, as well as road rebuild/drainage/resurfacing work near the Waitangirua Interchange and two sites north of SH58 Interchange (one near the Golf Course and another around the Battle Hill area. This will primarily affect the motorway’s southbound lanes. However, some work may be required for northbound lanes.

“This work programme will help ensure the road pavement is safe, smooth, and long-lasting. This will help reduce on-going maintenance costs and disruption along the motorway.”

Around 20 lane kilometres of State Highway 1 north of Porirua will undergo resurfacing, drainage upgrades, and rebuilds. The transport agency measures the distance over a 1km width of the highway.

He described the works as “part of remaining work not completed by the project’s builder before the project was restructured last year.”

But would not reveal the cost of the remedial programme, saying it was “still to be quantified”. Nor has the agency said where the expense will fall.

The uncertainty leaves open the possibility that New Zealanders will end up paying again for a motorway that was supposed to transfer risk to the private sector.

The lack of detail extends to a legal battle with the road’s builders, which Waka Kotahi settled out of court.

Infrastructure New Zealand Nick Leggett chief executive said it was understandably frustrating for motorists and transport users in the lower North Island.

“While it is sooner than many would have expected for maintenance of this scale to occur, it is vital that the work is undertaken to ensure the motorway continues to perform well for the region,” he said.

“New Zealanders expect infrastructure that stands the test of time. By learning from Transmission Gully and applying those lessons, we can deliver better outcomes in future projects.”

Transmission Gully has been dogged by disputes, delays and cost overruns since construction began.

Although it finally opened in March 2022 after years of setbacks, insiders revealed the motorway failed to meet contract standards, with surfacing and safety barriers among the major concerns.

The Public-Private Partnership (PPP) was set up to build the 27-kilometre motorway in 2017 with Wellington Gateway Partnership (WGP) ‒ a consortium who would design, construct, finance, and then operate and maintain the motorway for 25 years.

The official opening of Transmission Gully with a powhiri by Ngati Toa to welcome dignitaries including Sir Brian Roche, then Waka Kotahi Board Chair, front.

WGP hired construction companies CPB and HEB, to build the road. It would receive quarterly payments from the Government upon completion.

But construction issues, and the 2016 Kaikoura earthquake, dogged the project, adding delays and costs to the project and in 2020 Waka Kotahi agreed to pay nearly $200 million extra.

Then the pandemic hit and the builders used a force majeure event clause in their contract to renegotiate terms, hiking the price.

But then came a dispute over quality, including road surfacing, which needed to be relaid, barriers with insufficient height and other incomplete safety features.

A legal battle between the agency, WGP and the builders ended with a confidential settlement late last year.

It restructured the PPP with Waka Kotahi taking on greater responsibility for finishing the road and ongoing operations and maintenance.

CPB and HEB exited and Australian firm Ventia will operate and maintain the motorway for 25 years, with quarterly repayments to WGP continuing.

At the time, Waka Kotahi said the settlement did not bring increased costs for the taxpayer.

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