A $2.8 million project to stabilise the cliffs around Nelson's waterfront is expected to be finished in November.
New Zealand Transport Agency regional manager Mark Owen said it was the second phase of a large project to secure Rocks Road and the homes above, since major slips in 2011.
The storm tore away hillsides, destroyed homes throughout the region and damaged many others on Nelson's port hills, including one house on the cliff's edge that has since been removed. The slips also closed Rocks Road - which is part of State Highway 6 - for several days, and a main thoroughfare in and out of Nelson.
The project, which began in April, is being managed by Opus International Consultants, and Downer was awarded the contract to carry out the task. Contractors were now scaling near vertical heights to lay erosion netting, anchor the cliff face with massive bolts and spray shotcrete (super strong concrete) to seal the parts most likely to fail.
Site foreman John Hattersley of contracted firm Ground Anchor Systems, said between 10 to 14 people were working on the cliffs, and all were trained abseilers. Some parts of the cliffs were being anchored by large bolts from five to 12 metres long, drilled into the hillside, he said.
Lately there have been teams working through the night, to avoid too much disruption to the large volume of daily traffic on Rocks Road.
"At the moment we're doing some concrete work and scaling work. We stop the traffic so we can manage the material coming down off the hill," Mr Hattersley said.
Mr Owen said drainage was also being added, which was a critical part of erosion prevention. He said the type of work, which was like "highly technical icing", had been done in other parts of the country, but the rock face they were working with in Nelson was unique.
The $2 million-plus project represented a "significant cost" from the highways budget for a three kilometre stretch of state highway, Mr Owen said.