After a series of sub-tropical cyclones pounded the upper North Island in early 2017, the road infrastructure owned by Auckland Transport and managed by Broadspectrum suffered extensive damage. The coastal roads around Kawakawa and Miranda, southeast of Auckland, were the most severely impacted with over twenty dropouts affecting the road to varying degrees. In some instances, the road was completely washed away while in others shoulder loss prevented road usage.
Hiway GeoStabilization was awarded eight dropouts in the Kawakawa area of the network. Issued as design/build tenders, our years of experience in slope remediation allowed us to provide cost-effective, timely repair proposals. The solutions implemented included combinations of walls utilizing Geosynthetically Confined Soil™ (GCS™) services, micropiles, soil nails, and shotcrete. Executed utilizing our SuperNail™ design and installation services, all sites were remediated from the road level. This technique allowed us to implement the solutions while minimising disturbance to the beach and delicate coastal environment below.
The eight sites were completed on time and budget, allowing local residents, tourists, and commercial operators unhindered access to this beautiful part of New Zealand.
The project involved the design and build of 3 retaining walls to remediate slips, and increase the road width, Hiway Geotechnical’s design involved installation of micro piles, construction of a reinforced concrete footing.