Repair job won’t stop SH1 over Mangamukas in Far North reopening by Christmas; snail rehabbed with repairs to shell
Work is progressing on the SH1 repairs over the Mangamukas, with the road still on track to reopen before Christmas, despite some recent urgent repair work.
State Highway 1 over the Mangamukas is still on track to open before Christmas, despite an urgent repair job having to be carried out recently – on a damaged pupurangi/kauri snail that was found crossing the road.
NZ Transport Agency Waka Kotahi (NZTA) said work is entering the final stages of the slip repairs on State Highway 1 through the Mangamuka Gorge.
The work involves complex engineering solutions and large machinery working in narrow spaces to stabilise the road, with the goal to ensure safe travel by enhancing the road with advanced drainage systems and specific construction techniques, all while navigating the challenging landscape.
“We’re on track to reopen SH1 through the gorge by Christmas this year,” NZTA said.
The Waka Kotahi environmental team recently performed first aid on a local resident of the Mangamuka Gorge – a giant carnivorous pupurangi (kauri snail). These giants of the ngāhere (forest) are regular visitors to the Mangamuka Gorge road repair site.
The patient presented with minor damage to its shell, and as snails are known to have a strong ability to heal their own shells, first aid was applied to the shell in the form of applying medical “Steri-strips” to cover the shell crack and protect the snail from infection.
The snail was kept in a large plastic container filled with deep leaf litter and supplemented with worms, invertebrates and empty snail shells for calcium (an important dietary requirement for snails when they need to re-grow their shells). The container was kept in the shade under forest canopy for four days to keep it safe while it was vulnerable during the early stage of shell regrowth. It was then released into suitable habitat near to the capture site.
Protecting the environment while repairs are carried out is super important to NZTA and its partners – this is especially crucial as the Maungataniwha Range is home to a diverse range of native and endangered species.
Some of the special creatures found as work progresses include the pupurangi (kauri snails), copper skinks and the frequently seen tusked wētā. All native species found are moved deeper into the forest where they’ll be safe and will continue to thrive.
This mahi is part of NZTA working closely with New Zealand Environmental Management and hapū to regularly survey any species which may be affected by the repair work, and ensuring all creatures are relocated away from construction sites.
NZTA said despite recent storms, work at the gorge continues at pace, and many of the more than 35 slip sites are in the final stages of repair.
SH1 over the Mangamuka Gorge in the Far North has been closed twice in recent years. The 13km stretch of highway was wiped out by a series of 15 slips in a major storm in August 2022, a year after the highway reopened after a 12-month closure.
Repair work had been under way for less than six months when a storm in April 2023 resulted in another 20 slips – some massive – that covered 1.3km and required repairs.
Then heavy rain on June 19 and 20 that triggered a massive slip down the hill threatened to further delay the opening. Work is going on around the clock to get the job finished as soon as possible. The two-year job to fully fix SH1 over the gorge has been so extensive and complex that an extra $60 million to finish it was allocated in May’s Budget, taking the total cost to $160m.