The road connecting Otago to the West Coast was reopening from midday following a substantial moving slip.
The slip at Burke Flat on SH6 south of Haast on Monday afternoon as brought down down trees. Photo: NZTA
The slip was triggered by heavy rain yesterday and blocked both lanes of State Highway 6 south of Haast.
It is the only direct route between the two regions with the alternative requiring drivers to travel hundreds of additional kilometres along the east coast via Arthur's Pass.
Poor weather conditions prevented workers from clearing the slip yesterday.
Waka Kotahi Transport Agency maintenance contract manager Moira Whinham said the slip continued to move yesterday and overnight, and workers cleaned up the damage this morning.
The slip extended 30m-40m and had felled many trees, she said.
"The detour to get round that area is right the way through Canterbury and Otago so it's pretty significant. We're really happy that we could get this slip cleared and the road open in 24 hours so people can continue of their journey," she said.
"Drivers should expect delays as the crew works to fully re-open two lanes and also watch out for high winds which are not abating at this stage."
The agency has alerts for surface flooding between Haast and Hokitika in place due to forecast rain today and tomorrow.
West Coast Regional Council recorded 161.5mm as falling in 24 hours at Roaring Billy, Haast. More than 320mm of rain fell over six days.
Further south, the highway to Milford Sound will remain closed due to snow and a heightened avalanche risk.