Utilising innovative geohazard mitigation techniques, Hiway GeoStabilization (HGS) cut project costs in half on a land slip project on West Coast Rd, in the North Hokianga.
Instead of building a conventional retaining wall, HGS used high tensile wire mesh and steel anchor nails to stabilise the roadside. Far North District Council (FNDC) general manager infrastructure and asset management Andy Finch said the council was always open to exploring innovative and cost-effective methods of maintaining the district’s extensive road network, and this technique had real promise.
“Our geology makes us particularly vulnerable to slips, and these can be expensive and time-consuming to repair, this technique can significantly reduce the time required to complete repairs, and also uses fewer materials. That means costs can potentially be reduced by as much as half, while achieving similar levels of stability as traditional retaining methods,” said Andy Finch.
This was the first time the machinery required for the mesh and anchor technique had been available in the Far North, and the council hoped to be offered the option again by contractors tendering for slip repairs in the future.
After the Kaikoura earthquake in November 2016, the steep coastal slopes above the main State Highway (SH1), and the main trunk rail line, north and south of the town were severely affected by rockfall, landslide, and debris flow issues.