Work to fix the slip on SH31 near Kawhia will involve lengthy daytime closures for five weeks. Photo / Waka Kotahi
Work to fix the slip on SH31 near Kawhia will involve lengthy daytime closures for five weeks. Photo / Waka Kotahi
Slip repairs on SH31 Kawhia Rd have started and Waka Kohati NZ Transport Agency warns the work involves lengthy day-time closures for five weeks.
One lane of the road will be open on Anzac Day and on weekends, under stop/go traffic management.
Work to fix the underslip started yesterday. .Waka Kotahi and contractors have been working on a solution since the slip reduced the only sealed road to Kawhia to a single lane in mid-February.
An engineering technique called soil nailing will strengthen the site but because it is very narrow, with a steep drop-off, the road will need to be closed during the work.
The underslip is about 20km west of the corner of SH31 and SH39 at Tihiroa, and west of the Kawhia lookout. Photo / Waka Kotahi.
“The plan is to close the road each weekday at 8am, we will work until 12.30pm then open it for one hour, closing it again from 1.30pm to 5.30pm,” says Waka Kotahi system manager for Waikato, Cara Lauder.
“There will be no weekend work, with the road remaining open at single lane, but these day-time works and closures will be needed for about five weeks.”
The site can be cleared to allow emergency vehicles through.
Access in and out of Kawhia during the closure will be via SH39 to Ngutunui, Pekanui, Okupata and Oparau Rds back onto SH31. The detour has unsealed stretches and takes about 10 minutes longer than SH31.
The site has been operating at one lane with traffic lights and a speed restriction in place since the cracking developed in mid-February. Photo / Waka Kotahi
“I hope most people can get through our worksite while it is open but for those who can’t this alternative route is available for light vehicles and we advise drivers to take care,” Lauder says.
Since the underslip developed, there has been extensive geotechnical work to understand the cause of the problem and design a solution.
“The slip site is between two retaining walls and the piling under those walls we found was in good condition and provides stability for the work ahead,” Lauder says.
Soil nailing strengthens weak and unstable ground. A number of 12 metre-long steel bars will be driven in to strengthen and stabilise the ground.
“With reasonable weather in the past month and some initial work the slip has stabilised and we have been able to keep the road open,” Lauder says.
