Auckland Transport engaged Hutchinson Consulting Engineers to investigate an underslip on Coatesville-Riverhead Highway that had occurred late December. During the Christmas holiday period and following a period of extended wet weather, the subsidence significantly worsened resulting in complete loss of the roadside shoulder and vertical displacement within the southern side of the road.
Following Hutchinsons initial site investigation and reporting, it was identified that the construction of a 46m long palisade retaining wall was the most practical, long term engineering solution to remediate the site. Hutchinson completed detailed engineering design for the preferred remediation solution.
The palisade wall construction and pavement rehabilitation works were completed between April and July 2023.