State Highway 4 – Auraki Stream
Earthworks project restored a critical section of State Highway 4 at Auraki Stream.
The project began following significant slope instability caused by severe storms in June 2015. High flood levels in the Mangawhero River system eroded the land beneath the northbound carriageway, causing an underslip and the collapse of part of the road.
The remediation involved moving the highway up to 15 metres east of its original alignment and into the surrounding hillside. This required the construction of an entirely new road formation by cutting into and benching down a substantial slope.
Our team cleared more than 14,000 square metres of pine trees. Much of the timber was made available to the local community for firewood.
To make room for the new highway alignment, approximately 97,500 cubic metres of material was excavated and moved from the hillside.
A further 21,000 cubic metres of material was used in a nearby gully. This helped reshape the surrounding landscape, improve drainage and create additional usable land.
In addition to the main earthworks, our team completed a wide range of supporting works:
- Environmental and sediment controls
- Large-scale cut-to-fill earthworks
- New stormwater infrastructure
- Rock placement
- Farm fencing
- Site reinstatement
- Construction of a fish passage
From environmental protection and major earthmoving through to final reinstatement, the State Highway 4 Auraki Stream project was a significant undertaking – and one we are proud to have been part of.