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Project introduction

The 27 kilometre four-lane motorway will run from Mackays Crossing to Linden, through Transmission Gully. Four interchanges and two new link roads will connect the route to Mackays, SH58, eastern Porirua and Kenepuru. The Transmission Gully motorway is scheduled to be open for traffic in 2021.

  • Estimated project cost

    $1.25 billion
  • Project type

    Public Private Partnership
  • Project status


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Built to demanding specifications, the design and construction of the Transmission Gully motorway reflects the need for another route between Wellington and the lower and central North Island that will be safer and more reliable for motorists and better able to resist and recover from earthquakes and storms.

The project is highly complex, with difficult and steep terrain requiring large-scale earthworks during construction of the project. Twenty five new structures equating to a total length of more than a kilometre will be constructed along the route. The largest of these, the Cannons Creek Bridge, will stretch 230 metres in length and sit 60 metres above the valley floor.

The $850 million Transmission Gully motorway is being delivered as a Public Private Partnership (PPP) by Wellington Gateway Partnership in partnership with the New Zealand government. A key part of the Wellington Northern Corridor, the project is one of the most significant single pieces of new road construction in the lower North Island.


The Transmission Gully motorway will:

  • significantly reduce the number of fatal and serious injury crashes
  • increase capacity and passing opportunities
  • provide a more reliable and safer journey for motorists and one that is better able to resist and recover from earthquakes and storms
  • provide another route between Wellington and the lower North Island
  • reduce traffic congestion and improve safety within communities like Porirua by significantly reducing through traffic
  • reduce fuel costs and contribute to economic growth.

Project information

  • Partnerships

    In July 2014 the NZ Transport Agency signed a Public Private Partnership (PPP) contract with the Wellington Gateway Partnership (WGP), a private group of financiers and contractors, to design, construct, finance, and then operate and maintain the new motorway for the 25 years following the construction period. The motorway is scheduled to open for traffic in 2020. Read more >