Prime Minister Chris Hipkins will officially open the $880 million Pūhoi to Warkworth motorway this morning - a project opposed and mocked by Labour as a “holiday highway” and part of National’s “Roads of National Significance” programme.

Hipkins will be accompanied by Associate Transport Minister Kiri Allan at a ceremony to mark the completion of the new section of SH1 and the $62m Te Honohono ki Tai Matakana Link Rd that avoids Warkworth’s infamous Hill St intersection.

The two new roads north of Auckland are due to open to traffic over the next few days, possibly early in the morning to avoid heavy traffic.

Ara Tuhono Puhoi to Warkworth motorway State Highway. Photo / Supplied

The motorway has taken more than six years to build by the NX2 joint venture between Fletcher Building and Spanish construction firm Acciona, who under a private-public partnership will operate and maintain the road for 25 years.

The 18.5km new section of SH1 was initially due to open in the summer of 2021/22 and then at Queen’s Birthday weekend last year, but the impact of Covid pushed out the opening date by a further 12 months.

When the new motorway opens it will chop 11 minutes off the drive north and provide motorists with a safer journey to the windy and mostly single-lane road it replaces.

The drive begins with the impressive Arawhiti ki Ōkahu viaduct after the Johnstones Hill tunnels.

A couple of kilometres up the road at the Pūhoi turnoff spans a second viaduct before the four-lane motorway begins an undulating and curved path following the natural contours of the land as much as possible.

Halfway along the route are a spectacular series of steep cuts of Pakiri sedimentary sandstone and siltstone up to 65m high in thin horizontal layers and brick-like patterns laid over with wire mesh.

At the halfway point sits the steel Moir Hill bridge spanning two of the giant cuts, the steepest stretch of the road with a third, crawler lane each way for trucks and other slow vehicles.

The Puhoi to Warkworth motorway follows an undulating route. Photo / NZME

A prettier picture emerges towards Warkworth at the 75m long Arawhiti Pua Ngahere (Kauri Eco Viaduct) crossing a stream to a kauri forest and other significant native trees, almost within touching distance of vehicles.

When a four-lane motorway between Pūhoi and Wellsford was promoted by the last National Government, Labour’s transport spokesman Phil Twyford derided it as a low-value “holiday highway”.

He said Labour would postpone it and spend a fraction of the cost fixing accident black spots along the route.

Former Labour leader Phil Goff also promised to shelve the project indefinitely at the 2011 election. Goff lost the election to John Key, who went on to turn the first sod of the Pūhoi to Warkworth section in December 2016.

Ahead of today’s ceremony, Kiri Allan called it a “legacy project” and an exciting day for local communities and Northland.

Associate Transport Minister Kiri Allan. Photo / Andrew Warner

“This route is vital for the economy and will provide more predictable, consistent and reliable travel and better access to markets in Northland and to export ports at Auckland and Tauranga. That’s important for businesses to be able to plan their logistics,” she told the Herald yesterday.

Neither Labour nor National has publicly committed to building the next stage of Ara Tūhono from Warkworth to Wellsford any time soon.

Waka Kotahi NZ Transport Agency has the route and resource consents for the Warkworth to the north of Wellsford motorway that bypasses crash-plagued Dome Valley but does not anticipate any works starting on the corridor this decade.

National transport spokesman Simeon Brown said SH1 from Auckland to Whangarei is a critical corridor that needs greater investment, but the phasing and timing of any further work will be outlined in the party’s transport policy for October’s elections.

In 2020, the Labour Government announced it would build a four-lane motorway from Whangarei to Port Marsden costing $692 million, but 18 months later scrapped it for safety improvements only.