SH31 Kawhia Road repairs

7 March 2023

The under-slip on SH31 Kawhia Road as two gabion walls on each side.

Solution being formed for under-slip site

Work continues to develop the solution to an under-slip which has reduced SH31-Kawhia Road to a single lane.

The under-slip sits between two existing retaining walls, with soil nailing the likely option to reinforce and strengthen the area.

Geotechnical inspections have helped confirm the problem and solution and Waka Kotahi NZ Transport Agency hopes to announce a timeframe for this shortly.

“The good news is the piles under the retaining walls are in good condition and provide stability for the planned work,’’ says Waka Kotahi System Manager for Waikato, Cara Lauder.

Soil nailing strengthens weak and unstable ground. At the under-slip site, a number of 12m-long steel bars will be driven in to strengthen and stabilise the ground. The final result allows a steeper slope to be used in the final repair. Read more about soil nailing here

“We are working on what we need for traffic management, safe working methods, resourcing and programme for a speedy construction start.’’

The under-slip is about 20km west of the corner of SH31 and SH39 at Tihiroa. The site has been operating at one lane with traffic lights and a speed restriction in place since the under-slip was discovered mid-February.

“SH31 is the route in and out of Kawhia – and there are no sealed alternatives. We want to keep this road open but we may need to have full closures at fixed times during the day to get the repairs completed,” Ms Lauder says.

“We will be in touch when we have a confirmed plan including all traffic management needs and impacts of road users.”

About 800 vehicles a day use Kawhia Road and around 13 per cent are trucks.

 An aerial view of the Kawhia site taken on 1 March