A major route linking Nelson and the West Coast will be closed for at least several days after a slip left large rocks blocking the road.
State Highway 6 near Murchison was blocked by a number of large rocks that fell overnight.
The road is a major link between the Nelson region, the West Coast, and the inland route to Christchurch.
Some vehicles were initially trapped by the rockfall but have since been able to get moving.
Due to further risk of further rockfall, the road needs to be closed for several days while safety barriers are installed to protect traffic while the rockface is stabilised.
"You can see from the size of the boulders that came down earlier today there is a genuine risk to road users. Their safety is our priority," said top of the south systems manager Andrew James.
“It’s going to take some time to put these barriers in place. Once they’re in, we can open a lane of the road that is fully protected while contractors work to remove the rockfall danger. That single lane will be in place while the rock face is fixed."
It means there will be no direct link between Nelson and the West Coast via the Buller Gorge or Springs Junction.
Those wanting to drive from Nelson to Christchurch will need to go via State Highway 1.
It comes amid flooding and slips in parts of Canterbury which left a number of communities cut off.