NZTA developing plan of attack to clear gorge slip


The NZ Transport Agency says it is developing a plan to stabilise the hillside and clear the massive slip that is blocking SH3 through the Manawatu Gorge as quickly and as safely as possible.

NZTA Palmerston North State Highways Manager David McGonigal says that ongoing safety concerns have prevented the use of heavy machinery for clearing work since the 17 October slip.

Mr McGonigal said the continued instability of the hillside and on-going slips are the key challenges that need to be overcome, and the risks around allowing work crews to operate below the slip face and clear the road were too high for work to resume on-site until the hillside is stablised.

This decision has been made after close consultation with engineers, geologists and geotechnical engineers to determine the best way forward for the gorge.  In the interim, the NZTA is continuing its ongoing programme of work to maintain the alternate routes.

“We know how important this route is to the local economy. We are itching to get the slip cleared as soon as possible so people’s lives can return to normal, but we cannot put people’s lives at risk.

“We know this isn’t what people want to hear and we’re frustrated too, but given the latest massive slip on 17 October, the goalposts have shifted again and we’ve had to adjust our plans.

“Based on the precarious nature of the slip face and the development of the landslide to date, we expect further slips to occur, especially during heavy rainfall or strong earthquake shaking.  Some of these risks may still be significant, and the safety of workers is our top priority right now.”

Mr McGonigal says that to re-open the road, the NZTA will need to stabilise the hillside, then clear the slip material from the road, check the bridge structures and carry out remedial work.

Stabilising the hillside is the biggest challenge and the project team are currently looking at options to achieve this. 

“Every option we’re looking at has its own risks in regards to safety, effectiveness and time, and these all need to be carefully assessed before we go in all guns blazing.” 

Once further exploration of the options has been carried out, the NZTA will make a decision to determine which option is most practical, the safest to execute, and will minimise the length of the ongoing closure. The NZTA expects to announce its final plan of attack in the next two to three weeks.

Mr McGonigal reiterated the NZTA’s ongoing acknowledgement of the massive disruption this closure was having on the region, and thanked motorists and the local community for their continued understanding and patience.