Planning underway for West Coast Rd slip bypass

Contractors today began preparing to cut a single lane temporary passage along the edge of a major slip that closed West Coast Road between Panguru and Kohukohu on 19 August.

Northland Transportation Alliance (NTA) says the aim will be to provide limited vehicle access for communities that have been almost completely isolated by damage to local roads resulting from last month’s severe weather event. The cutting will allow restricted, light vehicle access over the slip. However, it will not open until after heavy rains predicted for Monday have passed, the site has been reassessed, and is confirmed safe for vehicle use.

According to MetService, up to 60mm of rain is predicted to fall in the area on Monday afternoon. NTA says this will increase the likelihood of new and sudden movement of the already waterlogged slip and that the delay is necessary to protect commuters and roading staff.

An initial assessment of the site conducted this week has indicated that the slip could be up to 10m deep. That inspection also showed that the slip is still moving, which will significantly complicate repair options. Before any repairs can be planned, bore holes will need to be drilled into the slip to confirm the depth of the unstable ground and to better assess future movement. A contractor with the specialist equipment required to undertake the work will be engaged in coming days.

NTA also plans to liaise with adjacent landowners to explore options of realigning the road away from its current path and installing dewatering infrastructure. However, the viability of these options depends upon results of a survey to establish the outer limits of the slip. Early indications are that unstable ground extends well above the roadway.

Meanwhile, work to repair another slip that reduced West Coast Road to one lane in July may begin soon. It is hoped that work can start rebuilding the road once exploratory test pits have been completed. The aim of the test pits will be to locate a firm base from which the road can be rebuilt. Work on the test pits is due to begin today.