The New Zealand Transport Agency says work on stabilising rocks above State Highway 6 at the Nevis Bluff near Queenstown is going well and should be finished in a month's time.
The bluff has caused problems for the agency for more than 10 years. A landslip once closed the road for weeks and millions of dollars have been spent removing unstable rocks from the area.
The latest blasting work began in March after investigations showed two areas of unstable rock about 160 metres above the highway.
The agency's spokesperson, John Jarvis, says workers are now bolting sections of rock to the hillside and the job is nearly done.