Te Ahu a Turanga: Highway construction enters new phase with first layers of asphalt

A convoy of trucks and other machinery work in sequence to put down layers of asphalt on the highway.

By Grant Kauri, owner interface manager, Waka Kotahi NZ Transport Agency

Construction of Te Ahu a Turanga: Manawatū Tararua Highway has reached an exciting new milestone with the first section of asphalt going down on the road.

Asphalt is known for its smooth, black surface that’s relatively quiet to drive on. It’s used on roads that have very high traffic volumes - like urban motorways - and roads that have steep gradients.

Te Ahu a Turanga’s pavement - that part of the road that traffic goes on - is made up of several layers equating to 790mm thick, and asphalt is just one of those. The pavement starts with a 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.

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 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 conveyor 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.

A total of 110,000 tonnes of asphalt will be used on the project - that’s about 9200 truck loads! Two asphalt plants will supply the asphalt volume required, one of which will be established on site from July.

Other updates from around the project

Construction of the bridge deck on Parahaki Bridge has reached the halfway point with 26 of 54 segments now completed.

The “stitch” connecting the span from pier 1 to the southern abutment is due to be completed in May. The form traveller that was operating from pier 1 is being moved to pier 3, where more bridge deck segments will be constructed.

At Eco-Viaduct, 6 of 11 sections of the bridge deck have been poured, with the team currently focusing on pouring the final pier.

After this is completed in June, they will resume laying the remaining 200 deck panels so the rest of the bridge deck can be poured.

The landscaping teams are in full swing, having started their planting season mid-April. They’ve already put 55,000 plants in the ground so far this year and expect to plant 180,000 by mid-July.

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.