Benefits Of Transmission Gully And Kāpiti Expressway Prove Value Of Large-Scale Infrastructure

Transmission Gully and the Kāpiti Expressway are delivering major economic and community benefits for the Wellington region, a new report for Infrastructure New Zealand shows. Together the new expressways are saving millions of hours of travel time, significantly reducing deaths and serious injuries, and providing a combined benefit of $173 million during the last calendar year.

Infrastructure New Zealand Chief Executive Nick Leggett says the findings of the report prepared by Infometrics underline the importance of delivering modern large-scale infrastructure.

“Transmission Gully has not been without challenges, but the benefits are undeniable. This stretch of new road alone is saving travellers nearly 2 million hours a year, making journeys safer, faster and more reliable, and helping unlock growth across the greater Wellington region.”

The report highlights:

• Transmission Gully delivered a $79 million benefit in 2024, driven by travel time savings and improved safety, with no deaths recorded on the road since it opened.
• Across the three new expressway sections – Transmission Gully, Mackays to Peka Peka, and Peka Peka to Ōtaki – the combined benefit was $173 million in 2024, with 3.8 million hours saved for those who used the roads and significantly fewer deaths and serious injuries.
• Porirua has been a major winner, with 74,000 more people now within a 60-minute drive of its CBD. This stronger connectivity is supporting local growth and helping to close the housing price gap with Wellington City, which has narrowed by more than $63,000 since Transmission Gully opened.

“The fact is these three new stretches of expressway are building more prosperous, more connected communities,” Mr Leggett, a former Mayor of Porirua says. “This shouldn’t come as a surprise as these are the outcomes we must expect from major infrastructure projects.”

“Better connections north and south mean more people can consider living further out of Wellington city, providing them more lifestyle options and easing housing affordability across the region. This is exactly why we must focus on delivering the next generation of large-scale transport projects that can transform our cities and regions.”

Kāpiti Mayor Janet Holborow says the benefits from the new roads are already being felt in her community. “We’ve been experiencing directly the benefits of Transmission Gully with easier and faster travel in and out of Wellington and the eastern areas of the region, and it’s great to have this information to back up what we’ve been noticing first-hand. When you add these benefits to what we’ve already measured in terms of economic benefit and visitor numbers it tells a really positive story. The reduction in injuries due to accidents is also extremely welcome news.”

According to Porirua Mayor Anita Baker, “Transmission Gully has been transformative for Porirua. We are now better connected to the entire region, and businesses have responded by choosing to base themselves here. The frustrating crawl through Mana and Pukerua Bay at peak times is a thing of the past, and so too are the frequent sirens that once signalled tragedy on an unsafe road. This highway has delivered real dividends – safer journeys, stronger connections, and new opportunities for our city. The next priority for the region must be Petone to Grenada.”

“When we look at future major projects for New Zealand, a second Mt Victoria tunnel and an additional harbour crossing for Auckland, while expensive, must be considered priorities of national importance,” says Leggett.

“The lessons from Transmission Gully and the Kāpiti Expressways are clear. Despite the well-known difficulties with the projects, they still prove that when we invest boldly, we can gain significant economic and social benefits.”

“The good news is that Wellington’s communities will benefit from these stretches of new road for decades to come.”

The report, Analysis of economic and social benefits of Transmission Gully and Kāpiti Expressway, is available here (https://infrastructure.org.nz/wp-content/uploads/2025/09/INZ-Transmission-Gully-Report_DIGITAL_Final_16.09.25.pdf)

Note:

Infrastructure New Zealand is the nation’s leading infrastructure member association. Our core purpose is to advance best practice development of world-class transport, energy, water, telecommunications, and social infrastructure for all New Zealanders. We do this through research, advocacy, and public and private sector collaboration. Our membership is comprised of over 150 organisations, including central and local government agencies, consultants, contractors, financiers, utilities, and academics – collectively employing approximately 150,000 people in infrastructure-related roles. Together, we are committed to creating a better New Zealand through outstanding infrastructure.

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