The Milford road, gateway to Milford Sound, is expected to reopen tomorrow to single-lane traffic after a giant slip blocked it for nearly a week.
NZTA area manager Peter Robinson said while over half of the slip had been cleared, heavy rain forecast for today was likely to delay work. Blasting cannot be done in the rain, but removal of material can.
Friday's slip has prevented traffic from passing the site on State Highway 94 and on Monday Mr Robinson predicted the road would be open for single-lane use by today.
Early reports the biggest of the rocks weighed 200 tonnes were "on the conservative side", he said yesterday. The slip, which covered about 200m of road, included rocks as large as 500 tonnes.
He said the largest rockfall had been blasted and cleared using explosives.
Equipment being used to clear the slip included drilling rigs and two large excavators.
Recommendations from geotechnical experts were being followed to ensure the safety of workers.
It could be some time before the cost of the work was known, Mr Robinson said.
