Work has begun removing slips blocking the Manawatu Gorge, after two came down late on Monday night.
A large, 3500-square-metre slip occurred near Woodville and a smaller one near Ashhurst.
NZTA says State Highway 3 will be cut off for three weeks while excavators and large trucks remove the dirt and rock.
Highway manager Ross I'Anson says work has begun clearing the smaller slip, and that's expected to be finished in the coming days. He says heavy rain in the area caused the slips.
Work will begin on the larger slip once engineers have checked the area is safe.
About 6000 vehicles, including large transport trucks, travel through the gorge each day.
Diversions are in place to the north along Saddle Rd and to the south along Pahiatua Track.