Te Ahu a Turanga: Manawatū Tararua Highway - Completion of earthworks makes way for road construction

With bulk earthworks now completed, attention turns to construction of pavements – the part of the road that traffic goes on.

Grant Kauri - the highway is expected to be completed mid-2025. Photo: RNZ/Jimmy Ellingham

OPINION

Three years after construction began on Te Ahu a Turanga: Manawatū Tararua Highway, bulk earthworks are completed, with more than 6.4 million m3 of earth moved.

This total equates to about 350,000 truckloads of earth. The number is slightly more than the 6 million originally anticipated, which was due to some of the earth moved not being suitable for road building.

“Bulk earthworks” refers to moving large volumes of earth, and while this part of the programme is completed, there are still minor touch-ups to be done. This includes activities like finishing works, which is making sure the top layer of earthworks is smooth and ready for pavement construction.

Overall, 320 people operated earthmoving equipment, with one operator moving a massive 260,000 cubic metres alone.

About 300 different pieces of equipment were used, with 70 per cent of the earthworks being completed using excavators (diggers) and dump trucks, with the remaining 30 per cent using scrapers.

Working closely with the earthworks teams are the drainage teams, who install the systems that keep water running away from the road.

This includes network drainage, which involves pipes under the road that carry water into treatment areas away from the highway, and pavement drainage, which ensures water drains away from the aggregate layers and into the network drainage system.

So far, 12km of pavement drainage and 5km of network drainage have been completed.

As earthworks and drainage are completed in parts of the highway, those sections are handed over to the pavements team to start constructing the road itself. About 6.5km of the alignment is ready for pavement construction.

Pavement construction began in June 2023, with layers of aggregate being laid on a 2km stretch of the highway near the western end.

As our pavement construction continues to make good progress, we are now preparing our layers for the supply and placement of the structural asphalt layers. A temporary asphalt plant is being set up on site to increase asphalt supply to the pavement crews.

New roundabouts at each end of Te Ahu a Turanga are taking shape, with the final earthworks trimming and drainage under way.

Following this, pavement crews will start to put down layers of aggregate over the next few weeks.

Bridges update

While the earthworks teams wrap up their programme, the structures teams continue to make progress on Parahaki Bridge, the 300m-long structure over the Manawatū River.

Using the form traveller from Pier 1, they have now completed 11 of 54 segments of the superstructure (bridge deck) and expect to connect this to the southern abutment by April.

Meanwhile, a second form traveller is being assembled on Pier 2, so more segments can be constructed at the same time.

Over the river at Eco-Viaduct, 224 of 760 deck panels have been placed on the steel girders, with a further hundred expected to go down over the next month. After this, concrete is poured over the panels, on which the road surface will eventually be applied.

At the Woodville end of the project, work continues on the bridge deck of Mangamanaia stream bridge now that all beams for this structure are in place.

More information

If you want to learn more about the project, head to www.nzta.govt.nz/projects/te-ahu-a-turanga/ or visit the Woodville Community Library and Information Centre for the latest flyover, project updates and the Drive the Highway simulator.