State Highway 1 north and south of Kaikōura will remain closed until at least the middle of next week after ex-Cyclone Gita brought down 300,000 cubic metres of debris over the road at 60 sites.
Since Tuesday morning, the route has been closed south of Kaikōura, between Peketa and Goose Bay, and north of the town from Mangamaunu to Clarence – the same sections where significant earthquake repairs were carried out following the magnitude-7.8 earthquake in November 2016. Though the rain dislodged less material than what fell during the quake, when over one million cubic metres buried roads and railway lines, the rockfall is still significant.
The biggest slip came down just south of Okiwi Bay, to the north of Kaikōura. About 200,000 cubic metres of rock and dirt fell there. The slips have also closed KiwiRail’s Main North Line, which runs alongside the highway.
NZ Transport Agency earthquake recovery manager Tim Crow said the slips were “very different in nature” to those caused by the quake and mostly came down at new sites. He said they would not require time consuming rock bolting and other slope protection like that needed after the earthquake.
About 95 millimetres of rain fell over Kaikōura in the 48 hours to 9am on Thursday, but it was heavier in the hills to the north and south of the town. MetService meteorologist Josh Griffin said 300mm fell at Rosy Morn, south of Kaikōura, during the ex-cyclone.
State Highway 1 is one of the major arterial routes in the South Island. It reopened only on December 15 after more than a year of repairs and had closed several times since due to weather conditions and ongoing rebuild work. This week’s closure leaves just one way in or out of Kaikōura – the difficult inland route via Waiau. Those travelling between Picton and Christchurch must use the challenging alternative route over the Lewis Pass (SH7).
Crow said crews were focused on getting a single lane of traffic open to reconnect Kaikōura. The reopening date will be reviewed on Monday.