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The project officially kicked off on Thursday 8 December 2016 when the first sods were turned

Northern Express Group marks one year of progress on Puhoi to Warkworth

One year in and there is plenty to get excited about on the Puhoi to Warkworth project. This is the second roading PPP in New Zealand, and the Northern Express Group (NX2) is making good progress tackling the task of financing, designing, building, maintaining and operating the motorway for up to 25 years.

The project officially kicked off on Thursday 8 December 2016 when the first sods were turned, signalling the official start of construction. Guests included then Prime Minister John Key, Hokai Nuku chairman Mook Hohneck, NX2 chairman Richard Didsbury and chairman of the NZ Transport Agency board Chris Moller.

The Puhoi to Warkworth project will create an 18.5 km, four-lane motorway starting at the northern end of the Johnstone’s Hill tunnels, and reconnecting with State Highway 1 (SH1) south of Kaipara Flats Road, just north of Warkworth. The new motorway will traverse land to the west of the existing SH1 and bypass Warkworth on the town’s western side.

The new motorway will have two lanes in each direction divided by a central median with a safety barrier. The existing SH1 will remain as an alternative route to the new motorway and will eventually become a local road owned by Auckland Transport. The motorway is scheduled to open to traffic by late 2021.

The project is in its first earthworks season, which includes significant culvert work

International standards

The motorway is being designed to international standards to be one of the safest roads in New Zealand. It will be an enjoyable driving experience, with a smooth OGPA (open-graded porous asphalt) road surface which reduces noise and water spray.

The road will follow the contours of the land as closely as possible and be curved and scenic. It will deliver a safe, resilient and reliable connection to the north for freight, tourists and other motorists, ensuring reliable and easy-to-plan journey times.

The road has also been designed to high environmental standards, including careful design to minimise the impact on kauri and other native forests. A significant ecological restoration and enhancement programme is being adopted.

NX2 is made up of companies with considerable experience in the design, construction, finance, maintenance and management of key infrastructure projects in New Zealand and overseas. The consortium partners funding the project are Accident Compensation Corporation (New Zealand), HRL Morrison & Co Public Infrastructure Partners (Australasian), Acciona Concesiones SL (Australia) and Fletcher Building (Australasian).

NX2 has subcontracted a construction joint venture (CJV) for these works comprising Fletcher Construction Company and Acciona Infrastructure. In turn, the CJV is subcontracting work to other firms, such as Beca and Tonkin & Taylor for design.

The first big job

After starting last January, NX2 has now cleared over 95% of the 164 ha of commercial pine forest and other vegetation. This was a huge job in some very steep and rugged terrain. They felled around 600 trees a day. Logging trucks then transported the logs to Northport in Whangarei and Ports of Auckland for export, or delivered them to local mills for pulping.

At its core, this is an earthworks project. There are 7 million cu m of cuts, 5 million cu m of fill and 1.5 million cu m of rock to be excavated. The project is in its first earthworks season, and this includes significant culvert work. During this first season the aim is to complete 20% of the required earthworks.

Extracting and crushing rock occurs onsite

To reduce transporting materials around the project, extracting and crushing rock occurs onsite. A 54,000 kg Terex rock crusher, affectionately known as ‘T-Rex’, is doing the job, and the project will be able to reduce deliveries of rock from other sources by up to 21,000 truck-and-trailer units over the next four years.


As the project is essentially offline with only a small portion of the project near Puhoi running parallel to the existing state highway, efficient and safe access is a big issue. The project has had to create a number of site access points, or SAPs, to access the project site, the biggest being SAP4, near Perry Road, south of Warkworth.

New rural intersection activated warning signs (or RIAWS) have been installed to alert traffic to reduce speed through the area. These electronic signs will show a 70 km/h reduced speed limit and will activate when SAP4 is in use by construction traffic.

NX2’s CEO Ray Wilson says, “Completion of SAP4 was a huge milestone for the project, and a lot of effort has gone into completing the works ahead of a busy earthworks season. Essential to this has been the traffic management along SH1, ensuring the travelling public and our construction team are kept safe during construction.”

Protecting the environment

The winter was wetter than expected, with 1300 mm of rainfall; a typical cumulative total for the equivalent six months is 837 mm. With such wet weather, managing erosion and sediment runoff has been a high priority for NX2.

Working closely with Auckland Council and adhering to the resource consent conditions saw a commitment to mitigate any potential effects on the freshwater and marine environments of the Mahurangi and Puhoi Rivers and their tributaries. The devices included silt fences, decanting earth bunds and sediment ponds.

Managing erosion and sediment runoff has been a high priority for NX2

One of the tricky jobs for the project has been the capture and release of geckos and other native fauna. The requirement to relocate nationally ‘at risk’ or ‘threatened’ species is part of a suite of resource consent conditions NX2 must comply with to minimise adverse effects on vegetation, animals, birds, fish and other species during the construction of the motorway.

Work began early in the project to identify and assess ecological habitats in the project area and find out what species were living there. Since then, the project team has been working closely with Auckland Council and the Department of Conservation to prepare predator-free sites for relocation.

A year on – in December last year – 36 forest geckos, one rarer Pacific gecko and one copper skink were resettled at a new predator-free site within the wider project area. The geckos had been at Massey University’s reptile facility for several months under the care of an expert team of herpetologists.

Progress report card

The NZ Transport Agency’s senior manager project delivery, Chris Hunt, says he’s pleased with how the first season of earthworks has gone. “The weather has been generally hot and dry through December and January, and that has certainly helped. Overall, the sediment erosion control work is going well, we’re on programme and we’re looking forward to two more productive seasons,” says Mr Hunt.

“Looking ahead, we’ll be making more use of the SAPs which join the busy state highway, so we’ll be working hard to communicate our safety concerns to the local community and other stakeholders. We urge all road users to be patient and vigilant around the SAPs as project vehicles enter or leave the traffic flow.”

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