The section of State Highway 73 remains closed while the work is undertaken.
During the rockfall, a truck driver was forced to seek refuge under a purpose-built concrete rock shelter.
A truck is trapped inside the rock shelter in the Otira Gorge on State Highway 73 as a rockfall comes down. Photo / Supplied
The truck and trailer was travelling down a steep section of the alpine route when it was forced to come to a stop under the rock shelter, as boulders one metre in size tumbled down, crashing on to the road and blocking traffic.
The driver was able to get out of the truck and was picked up by road crews and taken to Arthur's Pass.