A key Far North road closed due to skidding according to a politician, it may not be repairable because of the enormous amount of earth movement.
But even if it slips this year State Highway 1 through Mangamuka Gorge can be repaired, Waka Kotahi NZ Transport Agency and local leaders are now struggling to find a long-term alternative.
The gorge, just south of Kaitāia, is Closed indefinitely since a storm on August 18 and 19where heavy rain fell on top of a record wet winter.
But one storm of one in 500 years in July 2020 The same stretch of road closed for a yearwith slip repairs costing $16.2 million to fix.
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A serious accident on the closed road last week is another example of the dangers of the road.
The problem is not due to: a lack of maintenance but the steep terrain of the Mangamuka Gorge and the “plastic” soil type, which expands when wet and contracts when dry, said Far North deputy mayor Ann Court.
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Large areas of Mangamuka Gorge are affected by slips and not all are visible through native bush, Far North Deputy Mayor Ann Court says.
“It’s like an earthquake — there are those huge ruptures up to 1 meter high, because of the road there are so many, they go on forever,” she said.
“No matter how much money we throw at Mangamuka, that road will fail again. All the experts tell us there is no way to design that road so that it is not vulnerable to this kind of weather.”
Mangamuka Gorge – also called Maungataniwha, which translates to monster mountain – usually carries about 1,300 cars per day.
Randhir Karma, Waka Kotahi’s regional system design manager, said geotechnical surveys at 16 slip sites are now being analyzed but further geotechnical assessments were needed to get a clear picture of the damage.
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A woman who crashed into the sealed-off section of Mangamuka Gorge on Sept. 29 had to wait overnight to be rescued.
The agency cannot estimate the cost or time to reopen the road, but recognizes that Mangamuka Gorge ” faces a long-term problem with resilience,” he said.
Everything from tunnels under the mountain to the permanent closure of the road was brought to the table last week at a Waka Kotahi workshop with about 30 community representatives, Court said.
There were about a dozen alternatives, including: Upgrade SH10 to SH1upgrading an alternate west route through Broadwood and creating a new east-west route, such as through Otangaroa or Takahue Saddle, she said.
Each of these options has its challenges and will have people who don’t want their road turned into a state highway, the court acknowledged.
Vehicle only/delivered
This map of Waka Kotahi shows the diversion routes to and from Kaitāia now that Mangamuka Gorge is closed, with SH10 being the official diversion, but the western route through Broadwood is also used.
Even SH10 floods frequently at Kāeo and passes through townships like Coopers Beach and Taipā, she said.
More details on each option will be presented to Waka Kotahi’s board of directors in November, the court said.
But Kaitaia Business Association president Andrea Panther said people at the meeting told Waka Kotahi that the Mangamuka gorge needed to be repaired.
The canyon is the closest route between Kaitāia and the rest of the country, with other alternatives adding 30 to 40 minutes to a journey what some people do every dayshe said.
LAWRENCE SMITH/Things
Andrea Panther of the Kaitāia Business Association says the community wants the Mangamuka gorge repaired. (File photo)
“I don’t think we can be sure that Waka Kotahi will do the repair option we want until we see the geotech and engineering reports.”
The road closure is causing unrest in Kaitāia for residents and businesses alike, and has added a cloud to plans for the summer, when the area is usually packed with visitors.
“We are all afraid of what will happen in the summer if no one wants to come north because of the congestion” [on SH10]. We have some of the best beaches around and this summer should be a prime time to make up for Covid.”
Meanwhile, police are investigating an accident on the closed-off section of SH1, and people are wondering what the driver was doing in the closed-off area.
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The woman had to be stretched out of the Mangamuka Gorge after the crash, but it is still unclear what she was doing there.
A woman crashed her car on September 29, but waited overnight to be discovered due to lack of traffic on the road.
A police spokesman said the vehicle’s sole occupant was taken to hospital with serious injuries and is recovering from his injuries.
Kaitāia’s deputy fire chief, Ross Beddows, said the car was precariously tied to a tree and firefighters had to secure the vehicle while the ambulance carried the woman outside.
But the car was not badly damaged and the woman may have been injured after getting out of the car, he said.
“We were a little baffled at how she was in the canyon — she was very lucky the two contractors found her when they did.”
A spokesman for Waka Kotahi said it has 24/7 traffic management at Mangamuka Gorge, but access is still required for residents living in the gorge, contractors and emergency services.
“Parts of skid have been leveled where possible to ensure the road at creep speed is usable for these vehicles.”
The agency declined to comment further while the police investigation is ongoing.