The Manawatu Gorge is likely to be closed for a week after a slip reported to be "bigger than Ben-Hur'' came down last night following heavy rain.
Meanwhile the Desert Road between Waiouru and Turangi, State Highway 1, was reopened after ice had shut it down overnight, but a snow warning was still in place.
A very large slip had blocked the Manawatu Gorge, State Highway 3, between Palmerston North and and debris was still coming down, regional state highways manager David McGonigal said.
"Early indications are that the slip could take a week to clear,'' he said.
The Pahiatua Track and the Saddle Road were alternative routes.
Two trucks crashed overnight near the Makatote Viaduct, about 10km south of National Park, on SH4.
The road was down to one lane but could be closed later today when heavy lifting trucks were brought in to retrieve the trucks.
It was understood there were no injuries in the crash.