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Transmission Gully

Updated: 30 July 2014

The Transmission Gully project is a Public-Private Partnership (PPP) project to build a 27-km four-lane (two in each direction) motorway from MacKays to Linden (through Transmission Gully). There will be interchanges connecting the route to MacKays, State Highway 58, eastern Porirua and Kenepuru. The link to eastern Porirua will provide connecting roads to Whitby and Waitangirua. The Porirua City Council will be the authority responsible for those connecting roads.

Oblique view of the Transmission Gully Horokiri Stream. Battle Hill Farm Forest Park. Battle Hill artist simulation

PPP contract awarded - Construction phase next

29 July 2014

Initial work will begin in the third quarter of 2014 on the Transmission Gully motorway north of Wellington. This follows today’s announcement by the NZ Transport Agency that the contract has been signed for this project to be delivered as New Zealand’s first Public Private Partnership (PPP) for a state highway.

More information on the construction phase can be accessed on the Wellington Gateway Partnership website for the Transmission Gully project (www.tg.co.nz) or by ringing

  • Freephone: 0800 TG INFO (0800 84 4636),
  • or by emailing info@tg.co.nz

Public-Private Partnership (PPP)

The NZ Transport Agency has, in July 2014, signed a Public Private Partnership (PPP) contract with the Wellington Gateway Partnership.  Under the terms of the PPP contract, the Wellington Gateway Partnership will design, construct, finance, operate and maintain the new Transmission Gully motorway for the 25 years that will follow the expected five-year period to build the motorway. It is aimed to have the motorway open for traffic by 2020.

A Public Private Partnership (PPP) is a long-term contract between the public and private sectors covering the financing, construction and operation of a public infrastructure and services.  Full ownership of the public infrastructure remains with the public sector.

PPPs allow large and complex projects to benefit from private sector innovation and funding which can increase certainty of delivery and drive better value-for-money. There are also savings to be had on all aspects of the project - design, build, maintenance and operational management.

PPPs are typically used for large-scale infrastructure projects where risks can be effectively identified and transferred to the private sector. The NZ Transport Agency aims to use successful ideas and innovations that come out of the Transmission Gully PPP across other highway projects and the wider transport network.

More information on PPPs and the Transmission Gully project can be accessed under frequently asked questions.

Progress to date

July 2014 – The NZ Transport Agency signs a Public Private Partnership contract with the Wellington Gateway Partnership.  Under the terms of the PPP contract, the Wellington Gateway Partnership will design, construct, finance, operate and maintain the new Transmission Gully motorway for the 25 years that will follow the expected five-year period to build the motorway. It is aimed to have the motorway open for traffic by 2020.
http://www.nzta.govt.nz/about/media/releases/3531/news.html

December 2013 – The NZ Transport Agency announces the Wellington Gateway Partnership as the preferred bidder to finance, design, build, operate and maintain the Transmission Gully Public Private Partnership (PPP) motorway. The Transport Agency will now enter into PPP contract negotiations with the Wellington Gateway Partnership. http://www.nzta.govt.nz/about/media/releases/3012/news.html

April 2013 - The NZ Transport Agency announces the two consortiums shortlisted to deliver the Transmission Gully Public Private Partnership (PPP) project. These are the Wellington Gateway Partnership and the Positive Connection consortiums.  A request for proposal (RFP) will be issued to the consortiums and their proposals will undergo a rigorous evaluation process to select the preferred bidder for the project.
http://www.nzta.govt.nz/about/media/releases/2538/news.html

January 2013 – The NZ Transport Agency calls for ‘Expression of Interest’ from consortia (New Zealand and overseas) interested in and capable of delivering the Transmission Gully Public Private Partnership (PPP) project.
http://wwwnzta.govt.nz/projects/transmission-gully/docs/ppp-roi-ad.pdf

November 2012 - The Cabinet gives the NZ Transport Agency approval to finance and build the Transmission Gully motorway using a Public Private Partnership (PPP). The Transport Agency is also given approval to borrow up to the estimated costs of traditional procurement as part of the PPP. Final approval of the borrowing limit will be confirmed by the Cabinet before the Transport Agency awards the PPP contract.
http://www.nzta.govt.nz/about/media/releases/2304/news.html

August 2012 - The Minister of Transport directs the NZ Transport Agency to assess the suitability of using a Public Private Partnership (PPP) procurement model to design and build the Transmission Gully motorway.  Following an extensive business case analysis (using the Treasury’s better business case framework), the Transport Agency determined that the project meets the Treasury’s criteria for a PPP procurement model.
http://www.nzta.govt.nz/projects/transmission-gully/docs/business-case.pdf

June 2012 - The NZ Transport Agency welcomes the release of the Board of Inquiry's final decision to approve the regulatory consents applications lodged by the Transport Agency, Porirua City Council and Transpower for the Transmission Gully project. The Transport Agency says this will now allow for the project to be progressed towards construction.
http://www.nzta.govt.nz/about/media/releases/2026/news.html