State Highway 73 between Christchurch and the West Coast is unlikely to be re-opened until Saturday while contractors deal with a massive slip.
The highway between Arthur's Pass and Jacksons was closed by the slip early on Thursday morning when a storm hit the South Island, closing a number of roads on the Coast and in Canterbury.
While other roads had re-opened, the New Zealand Transport Agency says SH73 will remain closed on Friday.
More information would be available on Saturday and it was unlikely the highway would re-open before then, the agency said.
Photos showed debris several metres deep had blocked the road and covered the adjacent railway lines.