The Waioeka Gorge should be re-opened fully next week after a slip forced its closure last month.
The New Zealand Transport Agency (NZTA) is working to re-open the section of State Highway 2 between Ōpōtiki and Gisborne for 24 hours a day, from Tuesday next week.
Rockfall blocked the East Coast route on June 24 and the road was re-opened on June 30 but limited to daylight hours.
NZTA's regional transport system manager Rob Campbell thanked motorists for their patience.
"Our contractors have worked hard to build new lanes away from the slip to create a buffer zone where all drivers will be able to safely use the one-way section through the gorge site day and night, with the aid of traffic lights."
Campbell said the slip site needed to be monitored for safety reasons but NZTA was committed to keeping the "vital route" open.
"For safety reasons, we will have spotters on site for several weeks monitoring the hillside for any signs of instability, and we're currently looking at technology that can help us monitor the site remotely.
"While our spotters are on site we will continue to have a stop/go operation, which ensures we can very quickly close the road in an emergency and keeps our spotters safe."
He said the cause of the slip was likely to be a combination of heavy rain and ice.
"Once the water gets into the cracks from the hill above it gradually erodes and weakens the rock. When this water freezes the ice expands and lifts rocks which widens existing cracks until they become weak and fall off," he said.
"We want to remind motorists that there is still a chance that the gorge may need to be closed again for a period of time if weather conditions require it for safety reasons.
"We know that large amounts of water will increase the risk of more material coming loose, and we will not compromise on safety."
Since the initial slip came down on June 24, contractors have built a new lane to shift the road further away from the face of the slip site.
Over the next few days, contractors are finishing off the installation of barriers and fences before the road re-opens.
The gorge will continue to be open with reduced hours until Tuesday. It will be open from 6.45am to 4.30pm.