Mangamuka Gorge reopened after slip cleared

State Highway 1 over the Mangamuka Gorge in Northland has been reopened after a slip that blocked the road over the weekend was cleared.

NZ Transport Agency Waka Kotahi [NZTA] said engineers had been on site to carry out assessments prior to the reopening this morning.

There would be temporary speed limits in place and periods of stop/go traffic management while contractors continue to clean-up the highway, a spokesperson said.

NZTA thanked people for their patience during the closure.

“Please be patient, allow additional time for your journeys, and treat our crews with kindness and respect.”

The main highway through the gorge was closed following the slip, which was caused by torrential rain on Saturday night that continued into Sunday.

The slip was in a new area, not part of previous recovery works that closed the highway for two years.

An NZTA spokesperson said on Sunday that contractors had managed to clear a significant amount of slip material.

The site was monitored overnight as trees were still overhanging the road.

Far North Roading Group managing director Manu Burkhardt-Macrae said the latest closure was “disappointing”.

Road crews and arborists work to clear the slip that has blocked SH1 through the Mangamukas.

The Kaitāia-based civil construction company has “a lot of work in Kaikohe” which means taking the SH10 detour, he said.

“When the gorge is closed, we have to go round SH10 or through Herekino and Broadwood which takes an extra 45 minutes to an hour each way.

“It’s disappointing, but some of those things you can’t avoid.

“Over-slips, they can clear quicker than under-slips, so hopefully it’ll be a short-term closure.

“It does make the trip to Kaikohe longer and costs us time and money.”

The Mangamukas reopened in December after a two-year closure because of damage from severe weather.

It cost $204 million to repair the road due to 30 major slips.

Many Kaitāia businesses struggled while SH1 was closed as visitors stayed away, and motorists had to use the longer SH10 detour.

Kaitāia Business Association chairman Josh Kirby said the recent closure was a disruption for the business district.

“Freight movements in and out of Kaitāia are already impacted, putting immediate pressure on local businesses and supply chains.

“We are still trying to understand the full extent of the disruption and are awaiting an urgent update from NZTA.”

Kirby said the Far North had just experienced two weeks of heavy rain and large weather fronts, including former tropical Cyclone Tam.

“There was some expectation of teething issues after the reopening in December,” he said.

“However, repeated closures seriously undermine confidence, not only for visitors considering travel to the Far North, but also for businesses trying to plan ahead.”

Northland MP Grant McCallum said the road closure was “very disappointing”.

“But given the geology of Northland and the amount of rain we’ve had ... slips are a fact of life,” he said.

NZTA was working at pace to clear the slip, McCallum said.

“Geotech workers and arborists are on site this morning to sort it out.”

McCallum said future-proofing the gorge was difficult.

“We’ve just spent $200m fixing up the previous slips, which were devastating.

“We will always look to make the road as stable and safe as possible, but you can’t guarantee everything.

“NZTA has to make sure systems are in place so they can clear slips as fast as possible.”

NZTA said previous recovery work, including slip repairs and drainage improvements, have held up well.

MetService have placed a heavy rain watch on Northland in areas north of Whangārei from 10am until midnight on Tuesday.

Meteorologist John Law said there was a high chance of upgrading the watch to a warning but that would be updated as the forecast became more clear.

Periods of heavy rain with thunderstorms and localised downpours were possible for the region throughout tomorrow.

Law said the ground was already sodden from previous rain, making flooding possible. Rivers were also expected to rise.

Jenny Ling is a senior journalist at the Northern Advocate. She has a special interest in covering human interest stories, along with finance, roading, and animal welfare issues.