Delays are expected on State Highway 1 near Pukerua Bay after a slip closed the southbound lane.
The lane reopened shortly before 6pm.
Contractors and the police were working to clear the road and light traffic was being diverted to Paekakariki Hill Road, while heavy traffic was stopped at Fisherman's Table and let through as possible.
Police said the northbound lane could also need to be closed at Pukerua Bay to clear the slip.
Motorists were warned to delay their travel or take an alternative route.