State Highway 2, through the Waioeka Gorge, is now re-open after being closed by a large slip six days ago.
The Transport Agency said the gorge would be open to a single lane, from 7.30am to 5pm, under stop and go traffic management while the clean-up continued.
"We know these restrictions are frustrating and we understand the impact on the region of this vital route being closed and restricted.
"We have taken the decision to close at night to ensure the safety of the public and our staff," it said.
It said contractors had removed more than 7000 cubic metres of rock and earth that smothered the road last Sunday.
The agency warned there might still be delays in the area, and variable weather was expected in coming days, which could close the road again at short notice.
Motorists travelling at night will need to use State Highway 5 or 35.
Mayors in the region have been calling for the road to be improved for years.
The Transport Agency said it had been working with local government to try and stabilise the area.