The road through the Manawatu Gorge is likely to reopen at the end of the week, a month after it was first closed.
The state highway initially closed on April 24 following two slips, one at the Ashhurst end of the gorge, the other, a larger and more difficult slip at the Woodville end.
Then another 2000cu m of debris and rock fell overnight on Sunday, May 14, delaying the expected opening date.
Now the New Zealand Transport Agency says most of the slip material has been cleared and the road is expected to be opened at the end of this week, after the repair of damaged guard rails and the installation of concrete barriers to ensure travellers' safety.
The agency's highway manager, Ross I'Anson, said crews worked throughout the weekend to clear the last 2000cu m of slip material, with about 13,000cu m cleared from three slips since the road was closed on April 24 - enough to fill more than five Olympic-size swimming pools.
While the reopening's exact timing would depend on how quickly crews could repair and replace the guard rails and install temporary concrete barriers to protect road users from further rockfalls, Mr I'Anson said everything possible was being done to reopen by week's end, with single-lane access past the slip sites.
"We know how vital this route is for people in the region," he said.
"We are focused 100 per cent on reopening the road as soon as possible, and our crews are working hard to get the job done."
Poor weather and hazardous conditions forced a temporary halt to work last week, but heavy rain later helped bring down rocks and other loose material hanging over the road since the May 14 slip, allowing crews to work on clearing the road at the weekend.