The work to fully reinstate the highway was expected to cost up to $11 million and could be completed by mid-2013, he said.
"We have always said that once the slip face is stabilised, we will move to traffic flowing similar to a one-way bridge situation, where one direction has priority and courtesy is required.
"The road will remain a single lane until the permanent works are completed, at which point we will reopen as a two-lane road."
Mr Gliddon said the area was still a construction area and NZTA wanted motorists to treat it as such by driving to the conditions and applying the same rules as they would use when driving through a single lane bridge.
Close to 100,000 cubic metres of earth material has been removed from the road.
NZTA will focus on repairing the highway and putting in permanent measures to minimise the impact of large slips.
"The full reinstatement works will commence shortly and continue over the summer months."
Mr Gliddon says the permanent works involve moving the highway towards the Opatu Stream to provide room for a slip protection structure to be constructed at the base of the slope. The structure will help to confine a volume of material that comes down from the slope and will provide a protection barrier for the road and users.
"The history of this slope tells us that future large-scale slips are always possible and tend to occur every 12 to 14 years. We are never going to prevent these from happening. What we can do is minimise the effect they have on the road."
NZTA encourages all drivers to visit their highway conditions website at www.nzta.govt.nz or call 0800 4HIGHWAYS (0800 4 4449) before planning their journey.