The Department of Conservation has to spend $320,000 installing an escape tunnel from its underground coal museum at Denniston, in the wake of tighter regulations post-Pike River.
It was revealed almost a year ago that the new tourist attraction, located 170m inside an abandoned mine, may have to install an emergency exit.
The lack of a second escape tunnel was a major focus of the Royal Commission of Inquiry into the Pike River Mine disaster.
Work on enlarging the existing emergency exit tunnel at Denniston is now well under way. Contractors work when visitor tours are not taking place.
Geotech Ground Engineering is carrying out the work and staff are nearly halfway through the 179m-long tunnel.
DOC partnerships ranger Natasha Perry, of Westport, said 80m of the drive was done.
"They are progressing about 5m a day."
When completed, the tunnel will have a minimum height and width of 1.8m. Emergency lighting and fire detection will also be installed.
The underground coal museum opened in 2011 and includes a narrow gauge railway, which carries visitors underground into the old Banbury Mine.
DOC and the high hazards unit agreed in August that the work would be carried out within a year.
- The Greymouth Star