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petone to grenada link road banner

Project introduction

This project will significantly reduce congestion on the busiest part of the Wellington Northern Corridor between Grenada and Wellington and help optimise and realise the benefits of the other improvements being made to the Wellington State Highway network.

  • Estimated project cost

    $250-$270 million
  • Project type

    Road management
  • Project status


Project updates

Project Update - August 2018
P2G Project update - October 2016
Project updates, (PDF)
P2G Project update - April 2016
Project updates, (PDF)
P2G Project update - December 2015
Project updates, (PDF)

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We are considering building a new east-west transport link between Tawa/Porirua and the Hutt Valley. The aims of the Link Road are to improve travel on two of Wellington’s main highways, support the region’s economic development and help make the transport network more resilient to major events.

The route will include redesigned interchanges at Petone and Tawa and a new interchange and connection to the Mark Avenue roundabout. The link road will provide better access on and off State Highways 1 and 2 and add future highway capacity north of Tawa within the existing highway footprint between Tawa and Transmission Gully when it is needed.

Objectives of the Petone to Grenada Link Road

Over the course of this project, we have refined our objectives to capture the specific economic and transport-related benefits that we are seeking to achieve.

The objectives for the Petone to Grenada Link Road are to:

  • enhance local, regional and national economic growth and productivity for people and freight
  • improve connectivity between the lower Hutt Valley and Johnsonville and Porirua
  • reduce journey times and improve journey time reliability between the lower Hutt Valley, Ngauranga and Porirua, and on the Wellington state highway network
  • enhance safety of travel on the Wellington state highway network
  • enhance resilience of the Wellington state highway network and
  • manage the immediate and long term social, cultural, land use and other environmental impacts of the Project on the Wellington region and its communities by so far as practicable avoiding, remedying or mitigating any such effects through route and alignment selection, expressway design and conditions

 By developing and constructing a cost efficient new road alignment to expressway standards between SH2 in the lower Hutt Valley and SH1 north of Ngauranga.


The Link Road represents a substantial investment in the region's transport needs. It can benefit all road users, support public transport and could contribute to more walking and cycling opportunities when combined with projects like the Wellington to Hutt Valley Walking and Cycling Link.

Reduced congestion – SH1 and SH2 are reaching capacity during peak periods. SH2 is particularly affected by daily congestion in the peak hours, unreliable journey times, delays and a lengthy detour via State Highway 58 if the road is closed or blocked. The Link Road will reduce journey times and improve journey time reliability between the lower Hutt Valley, Ngauranga and Porirua, and on the Wellington State Highway network.

Economic growth - The link road will support our region’s growth, enhance our ability to get goods and services to market and reduce difficulties for those travelling for work, education, business, health or family needs.

The Link Road will improve freight connections by providing more transport choice between Lower Hutt, Wellington and Porirua as well as Upper Hutt and Kapiti. More choice means companies can access markets more easily, making products more affordable.

Increased resilience - The Petone to Grenada Link Road will be designed to be more resilient to minor slips that close or block the highway as well providing an alternative route in the event of major issues such as a national disaster that could affect thousands, particularly in the Hutt Valley if help can’t get to them.  

Improved safety - Three sharp curves on SH1 will be realigned to address an ongoing risk to travellers. The new route will include modern safety features.

Issues and constraints

In developing our options we have identified the following issues and constraints:

  • ecological impacts (ie issues associated with proposed routes passing through open spaces and parks or crossing the Horokiwi Stream)
  • geotechnical issues associated with the rock structure
  • ecological and consenting issues with earthworks required through contaminated former landfill sites
  • topographical constraints regarding horizontal curves and gradients because of the steep and hilly terrain
  • land acquisition issues
  • visual impacts
  • other social concerns.


The timeline is being reviewed and adjusted. A new timeline will be released in 2018.

Next steps

In mid 2017 we undertook an internal evaluation of the scheme. The evaluation report and executive summary can be found here.

In early 2018 we will collaborate with local councils to:

  • review the project objectives, including the priority to be placed on resilience
  • review the current scheme’s expressway requirement to ensure that the standards are appropriate for the transport solution that the link road is to provide. This may help reduce construction costs, environmental impacts and deliver a more resilient outcome
  • further investigate safety and whole-of-system opportunities, including providing multi-modal choices for customers, technology solutions and demand management
  • re-test alternatives and options to reduce construction costs and provide improved resilience outcomes
  • further investigate the project’s ability to be integrated into the wider transport system (e.g. Hutt City Council’s east-west connections project, Hutt Valley to Wellington Cycleway Project, SH2 Melling Interchange)
  • further develop the managed motorway proposal for the section of the SH1 between the new Transmission Gully interchange and the proposed P2G project Grenada interchange (including the timing of its implementation).

Upon completion of the above work, we expect to be ready to re-engage with the wider community in early to mid-2018.

Preferred alignment

The alignment of the proposed new transport route for the Petone to Grenada Link Road was confirmed in November 2015. The proposed new transport route will:

  • provide a four-lane route between Petone and Tawa, plus crawler lanes on the Petone side
  • run between Petone and Tawa via the Horokiwi Crest (largely avoiding homes in the Hunters Hill area
  • be constructed mostly in-cut through Horokiwi to reduce visibility from Horokiwi and much of the Hutt Valley
  • redesign the Petone and Tawa interchanges and create one new interchange, providing better access on and off State Highways 1 and 2
  • not impact the Belmont Regional Park and
  • provide future highway capacity north of Tawa on SH1 within the existing highway footprint between Tawa and Transmission Gully when it is needed. 
  • 2015 preferred alignment diagram

    View larger Preferred Alignment diagram [PDF, 4.2 MB]

    The process to determine a preferred route has been significant.  The options have been modified to take into account technical expert advice, differing opinions and feedback of landowners, community representatives, stakeholders and the public and to optimise the proposed new transport link.

    The end result is a transport route that addresses critical issues affecting day-to-day travel and future requirements, such as the ability to manage the transport network during major events or making the region a more attractive place to live and do business by improving journeys between Wellington, Porirua and the Hutt Valley.