Work to get a temporary road in place around the State Highway 4 slip is progressing with contractors undertaking drainage and revegetation work at the site.
Now NZTA says it expects a temporary road could be in place early next year.
The Parapara road has been closed since early October after it was significantly damaged by a major slip.
Crews moved onsite last week after testing confirmed it was safe for contractors to work on the slip face.
Although the site is still vulnerable to further slippage, especially in heavy rain, recent geotechnical assessments have given NZTA confidence that the construction of a temporary road can begin.
Regional transport systems manager Mark Owen said NZTA was working to restore access as soon as possible.
"We expect that a full temporary road could be completed early next year," he said.
"It is likely that there will be limitations on its use. The road will be under constant observation and should it be deemed unsafe at any time, we will close the road immediately and possibly at short notice.
"Safety is our number one priority so we're constantly monitoring the site for any movement that could make it unsafe for our workers, but we're pleased with how the work is progressing so far."
Many of the contractors working on the slip are staying in the region, with many opting to base themselves in Raetihi.
"We'd like to thank the community for their warm welcome and friendly hospitality," Owen said.
"Since the closure of the road, they have been very patient and understanding.
"While we build the temporary road, we are also exploring a range of long-term options to permanently reinstate SH4.
"We hope to be able to announce a preferred option in the coming months."
The recommended detour is via State Highways 1, 49 and 3, and will add at least one hour to the trip between Raetihi and Whanganui.
Alternative routes via Fields Track and Whanganui River Rd are not suitable for heavy vehicles or large volumes of traffic.