ACCIONA's first project in New Zealand

Construction of 18.5 kilometres of highway with four lanes between Pūhoi and Warkworth with 100 km design speed.

The project includes the design, construction, financing, operation and maintenance of the SH1 Highway Expansion in northern Auckland.


The public-private partnership (PPP) contract award to build the stretch of the Pūhoi-Warkworth highway is ACCIONA's first project in New Zealand, which consists of the 18.5-kilometre four-lane North Highway extension from Johnstone Hills tunnels to North Warkworth.


This is the first stretch within the Ara Tūhono - Pūhoi to Wellsford passage, which will contribute to the economic growth of the Northland region and provide a more reliable and secure transportation link with the triangle formed by the cities of Auckland, Waikato and Tauranga. Traffic from the Puhoi to Warkworth highway has opened in 2023.



Click here to visit the project website or view a construction update here.


  • Location: Auckland - Warkworth, New Zealand.
  • Contract type: Design, construction, finance, and maintenance for a 25 year period.
  • Infrastructure: Design and construction of 18.5 km highway.
  • Project value: AU $676 million.
  • Year of project completion: 2023


The building of the motorway has involved design and construction of the 18.5km road from Pūhoi to Warkworth, consisting of four lanes from the Johnstone Hills tunnels to the north of Warkworth, which will be the first section of the Ara Tuhono.

  • NX2 proposal complies with NZTA’s design, constructions and operational outcomes.

  • Improved safety for the new highway with our new Operating Speed design, which is designed to ensure on average each vehicle is travelling at its maximum performance, exclusive of stops and traffic. conditions

  • Predictable journey’s will be established through constructing grade-separated infrastructure, while using SIDRA traffic modelling to determine volume caps for traffic movement using micro simulation.

  • The Transport Agency is a primary key Stakeholder, meeting P2Wk’s consenting and regulatory requirements through the Urban and Landscape Design Framework, including the involvement of stakeholders and communities through the Urban Design and Landscape Sector Plan process.

  • Optimized pavement through optioneering by minimal expense on maintenance through pavement resurfacing and rehabilitation which will contribute to a high quality asset.



  • Enhanced safety and motorway resilience.

  • Supports economic and population growth.

  • More reliable travel times through the construction of grade-separated infrastructure.

  • Improved freight connection for Northland to the Upper North Island freight triangle (Auckland, Waikato and Tauranga).

  • The requirements of the Urban and Landscape Design Framework integrates in the sensitive landscape, minimizing the impact on the Kauri forest alongside its native species of flora and fauna.

  • The southern section of heritage significance for Hokai Nuku and this has been considered in the alignment and conception of the Okahu and Pūhoi Viaducts.

Key figures


km of two-lane highway


People working on the project at its peak


lane extension




hectares of vegetation cleared


vehicles per day by 2026


metres of culverts

Awards and recognitions

Technology and innovation

Geometric optimisation

ACCIONA was awarded the project in 2016 by the New Zealand Transport Agency after an 8-month competitive dialogue process where engineering value was considered one of the Client's main criteria. 

Geometric optimisation guided the design throughout the process based on a cost-effective solution using a field-adjusted curvilinear alignment where the operating speed criteria allowed for the best design. A consequence of the terrain-adapted geometry is that the new alignment offered fewer structures and shorter viaducts. The final result was a reduced total length of structures from 2,350 m in the Conceptual Design to approx. 800 m long in the final design.

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