Australian tunnel safety and disaster expert Arnold Dix has urged rescuers in Nepal not to give up hope of finding survivors inside the tunnels of the Upper Trishuli-3A hydropower project, where scores of workers are feared trapped underground days after a devastating flash flood.
“The operation at Trishuli 3A is proceeding as a rescue, not a recovery,” Dix, who is remotely assisting the operation, wrote on LinkedIn. Footage recorded around the time of the August 26 flood shows around 30 people moving toward and seeking shelter in the power station tunnels, he said.
Dix, who helped advise the 2023 Silkyara tunnel rescue in northern India where all 41 workers trapped after a collapse were brought out alive after 17 days, said tunnels can remain comparatively stable after devastation above ground and may preserve breathable air and survivable spaces. “Silence is not evidence of death. It is only the absence of a signal,” he wrote, citing past rescues in Chile, Thailand, and India where people survived underground for days without contact.
Rescue teams are still trying to reach workers at more than a dozen hydropower sites along the Bhote Koshi-Trishuli corridor. At Trishuli-3A, a 93-member team is working with Chinese tunnel specialists, while teams from India and South Korea are assisting operations at other sites. Dix described the scale of Nepal’s current operation as being like “23 Silkyaras going on at the same time.”
Nepal’s National Disaster Risk Reduction and Management Authority said on Thursday that 1,252 people have died and 4,216 remain missing. Around 900 people working at hydropower projects are among those still unreachable, while 11,993 people have been rescued. More than 21,000 security personnel have been deployed across the affected areas as rescue teams clear mud, rocks, and damaged roads.
The flood swept away settlements near Nepal’s border with China, and the authorities estimate around 20,000 homes will have to be rebuilt in safer locations. The disaster has left communities along the Bhote Koshi-Trishuli corridor traumatised, with rescue efforts hampered by mud, water, and damaged infrastructure. The Nepali Army has been recovering bodies from tunnels in the region, including the Langtang tunnel, as the search continues.
Rescuers have been using rafts and drones to hunt for survivors at the flood-stricken power plant, and voices have reportedly been heard at the site where scores remain trapped. The operation is being treated as a rescue mission rather than a recovery effort, with teams working around the clock to reach those still underground.
The disaster has raised fresh questions about the safety of hydropower infrastructure in Nepal’s mountainous terrain, where flash floods and landslides pose recurring risks. The government has pledged to rebuild homes in safer locations, but the immediate priority remains reaching the hundreds of workers still unaccounted for in the tunnels.