The slip above the highway, near the intersection with State Highway 8B and Deadman's Point bridge, began to move a week ago with traffic reduced to a single lane.
NZ Transport Agency maintenance contract manager Mark Stewart said shipping containers were placed along the base of the slip on Friday, allowing two-way traffic to resume, with speed restrictions.
The (estimated) 9000 cubic metre slip was sluiced last week using two helicopters, removing loose material and enabling geotechnical advisers to get a closer look at the underlying material.
"Over the weekend we continued to monitor the slip closely and there was between 20 and 30cm movement at different points on the site,’’ Mr Stewart said.
"We have now started de-constructing the slip on both the north and south sides.
"On the north side an excavator is completing track cutting and preparatory work to gain access to the northern edge of the slip.’’
From there it would remove some of the larger rocky material at the top and reduce the weight above the lower slope, he said.
"On the south side, abseilers have been placing air-bags in established cracks and unstable rocks are now being dislodged.''
Mr Stewart said the work will continue for several more weeks so road users should continue to build in an extra 10 to 20 minutes just in case traffic is temporarily stopped while rocks are safely being dislodged.
"The slip is moving at different rates in different locations, and the scale and complexity means it will take some time to safely stabilise the site.
"We are constantly monitoring the slip to ensure that the road remains safe for people to use.''
State Highway 8 is the main link between Alexandra and Cromwell, through the Cromwell Gorge, with no convenient detour route.
