Asphalt construction marks key milestone for Te Ahu a Turanga – Manawatū Tararua Highway


Construction of the road surface on Te Ahu a Turanga – Manawatū Tararua Highway is in full swing with the first layers of asphalt now in place.

Since asphalting started in early May, about 5,000 tonnes has been laid on the highway, mostly at the western end of the site. 

NZ Transport Agency Waka Kotahi (NZTA) project spokesperson Grant Kauri says the appearance of the smooth, black asphalt layers is a sign the project is entering a crucial stage.

“The first layers of asphalt have gone down in Fill 9 at the Ashhurst end of the project, which is close to where earthworks began back in January 2021.

“This milestone is the culmination of three and a half years of hard mahi by our teams, which have laid so much of the groundwork for us to get to this point.

“A total of 110,000 tonnes of asphalt will be used on the project – that's about 9,200 truck loads,” says Mr Kauri.

“Two asphalt plants will supply the asphalt volume required, one of which will be established on site from July.”

The road surface (pavement) on Te Ahu a Turanga is made up of several layers, which, all combined, are 790mm thick. 

After earthworks are finished, pavement construction begins with the placing of lower subbase, a 350mm-thick layer of aggregate that’s compacted using rollers. On top of this, the 230mm-thick subbase is constructed using a layer of aggregate mixed with cement to stabilise it. This layer is then chip sealed for stability.

The next layer is 160mm-thick structural asphalt. This formula is very strong, resistant to moisture, and holds up well on steep gradients. A final 50mm asphalt surfacing layer will be laid on top closer to the road’s opening.

A convoy of machinery is needed to apply the asphalt. It starts with a truck, which tips the asphalt into a machine following closely behind. That machine disperses the asphalt evenly along a conveyer belt out the back and into the paver, which has a screen that ensures the asphalt is spread out on the road to the right level. A roller then goes over it to compact the asphalt.

Elsewhere around the project, good progress continues to be made on the major structures, with another significant milestone being reached at the 300-metre-long Parahaki Bridge, across the Manawatū River.

The team has completed the first ‘stitch’ connecting the main bridge deck between Pier 1 and the southern approach or ‘abutment.’

Having poured 26 of 54 segments which comprise the bridge deck, the team is on track to complete all segments by the end of this year.

Over the river at the Eco-Viaduct Bridge, seven of 11 sections of the bridge deck have been poured. The final pier is due to be completed this month, after which the remaining sections of the bridge deck will be poured.

This bridge is also on track for completion by the end of the year.

Working alongside the construction teams are the project’s landscapers, who have already planted more than 55,000 plants since the start of the season in April.

This year they aim to put 560,000 plants in the ground, bringing the project plant total to 1.8 million.

Mr Kauri says the highway is scheduled for completion in mid-2025.

“Our intention is to open the highway as soon as possible, so our focus remains on constructing a robust, resilient road to restore this key transport link for the lower North Island.”

To view the latest flyover video of the construction progress, which this month includes a comparison between January 2021 and May 2024, head to our project page.

Te Ahu a Turanga – Manawatū Tararua Highway