Workers are lining up to join the city's first formal course on the use of explosives in construction, launched to meet demand for such skills for big projects due to start soon.
The Construction Industry Council, which is running the course, expects 300 shot firers will be needed over the next two years.
There are only 58 registered shot firers in the city and most are in their 50s or 60s.
Projects that will require explosives skills include the MTR's Guangzhou-Shenzhen-Hong Kong express rail link, West Island line and South Island line.
The council aims to run at least four classes a year, each with 20 students. The first class started last month and there are 110 people on the waiting list.
Previously shot firers - who control the explosives needed for works such as tunnels and demolitions - were trained on the job.