Simpson Grierson, together with Allens, has advised the Northway Consortium, comprised of ACCIONA Construction, ACCIONA Concesiones and Aberdeen Investments, on the Warkworth to Te Hana motorway, New Zealand’s largest roading public-private partnership (PPP), which reached financial close with the NZ Transport Agency Waka Kotahi (NZTA) on 30 July 2026.

The firm acted in two capacities. Simpson Grierson was sole legal adviser to ACCIONA Construction, the party responsible for the design and construction of the road, led by Construction Partner Lisa Curran. Separately, acting alongside Allens, Simpson Grierson acted as New Zealand counsel for the Northway consortium’s equity sponsors, Aberdeen Investments and ACCIONA Concesiones, led by Corporate Partners Catherine Shipton and Edward Norman.

The $3.6 billion project will deliver a 26 kilometre, four-lane motorway between Warkworth and Te Hana, with an interchange at Wellsford and twin tunnels beneath the Dome Valley, forming part of the Ara Tūhono Northland Corridor. It is being delivered by Northway Consortium in partnership with NZTA under a long-term PPP, where Northway is responsible for the design, construction, financing, maintenance and operation of the motorway for a 25-year term. The transaction also includes a partnership with Hōkai Nuku for the Ara Tūhono project.

A milestone for New Zealand’s infrastructure market

Simpson Grierson Construction Partner Lisa Curran, who led the firm’s advice to ACCIONA Construction, says the design and construction mandate reflects the depth of the firm’s construction practice.

“Acting as sole counsel to the design and construction contractor on a project of this scale was a significant undertaking. We worked closely with the talented ACCIONA Construction team on the contract arrangements and project documents at the heart of the PPP model and worked through some complex issues posed by the challenging natural environment the W2TH Road traverses. The culture the Northway consortium built during the bid phase, and the strong leadership shown by key people across all parts of the consortium, was truly inspirational and a career highlight for me. We look forward to working with ACCIONA on this project and others in the future,” says Lisa.

New Zealand’s largest PPP transaction

Corporate Partner Catherine Shipton says the transaction is a significant marker for privately financed infrastructure in New Zealand.

“This is the largest roading PPP New Zealand has undertaken, and reaching financial close on a project of this scale and complexity is a real achievement. It sends a clear signal to international sponsors and financiers that New Zealand can structure and deliver infrastructure of this magnitude.

“Working alongside Allens, we were pleased to bring the New Zealand law perspective to the consortium through a long and demanding process. It is a project that matters for Northland and for the country, and we are proud to have played a part in getting it over the line,” says Catherine.

Transaction detail

Simpson Grierson advised across two workstreams, including:

• Design and construction: as sole legal advisers to ACCIONA Construction, advising on the design and construction contract and other contractual arrangements together with property and planning advice related to delivery.

• Project documents and DD: providing New Zealand law advice on the project documents entered into with NZTA and due diligence on the project.

• Equity and sponsor arrangements: as New Zealand counsel alongside Allens to ACCIONA Concesiones and Aberdeen Investments as equity sponsors, advising on the consortium and equity investment arrangements.

• Financing: New Zealand law aspects of the debt financing and security package supporting the project.

• Regulatory and property: planning, land and regulatory workstreams associated with the corridor.

Simpson Grierson team

Lead Partners:

• Acting for ACCIONA Construction as D&C Sub-contractor: Lisa Curran

• Acting for the Contractor, with Aberdeen Investments and ACCIONA Concesiones as Equity Sponsors: Catherine Shipton, Edward Norman

Team: Greg Allen, James Hawes, Tara Wylie, Sarah Mitchell, Matt Conway, Dominic Toomey, Will Barnes, Dania Alsagoff, Ed Warren, Jade Magrath, Georgia Kellow, Isabel van Tuinen, Briana Lyons, Cody Dalton, Liam Brennan, Sarah Heslin.