Lower Buller Gorge drivers should plan for delays of up to 50 minutes every hour from 8.30 am to 5 pm on Friday, 1 September and Saturday, 2 September.
Abseilers will be dislodging rocks near Summit Creek on State Highway 6, between Inangahua and Westport.
Hard granite rocks have been falling intermittently in the last two or three days from the cliffs above the highway.
Drivers will be able to get through at the top of the hour for ten minutes, says Transport Agency Journey Manager, Lee Wright.
Temporary speed restrictions are likely to be posted at this site to enable drivers to take care around this unstable area while the risk is being reduced.
Updates at this site: http://www.journeys.nzta.govt.nz/traffic/roadclosures/182572(external link)
How to stay up to date:
Drivers can also call 0800 4 HIGHWAYS (0800 44 44 49) to speak to the call centre team for traffic and travel information.