State Highway 85 in Otago has reopened on Friday night after weeks of closure to improve drainage and prevent further slips.
Waka Kotahi maintenance contract manager Jennifer McLean said a section of the highway commonly called the Pigroot, which had suffered slips for many years, had been shut since 29 August so crews could install trench drains.
They would help improve the hillside's stability and divert water away from the slip site, McLean said.
The stretch of highway between Palmerston and Kyeburn is a popular route connecting Central Otago, Dunedin and Oamaru.
But motorists should expect minor delays and changing traffic conditions because the road is not expected to be sealed until next week, if the weather stays dry.
Crews will also reinstate the guardrail and carry out some final drainage works in the nearby paddocks.