The New Zealand Transport Agency hopes to re-open today what's become a notoriously volatile stretch of road near Haast.

Heavy rain over the weekend brought more than 20,000 tonnes of rock and gravel down onto State Highway 6 at Diana Falls.

The same area was closed for over a week earlier this month after another massive slip came down, and also where two Canadian tourists are thought to have been hit by a land slide and pushed off the road.

NZTA West Coast Senior Asset Manager Mark Pinner expects contractors will get the road re-opened by this afternoon, but that is very dependent on being no further rain or material falling down.