Indian rescue teams crept forward Tuesday in a painstaking dig by hand through rock and rubble towards 41 workers who have been trapped in a collapsed road tunnel for 17 days.
Soldiers and skilled miners are using a so-called "rat-hole" mining technique to clear the final stretch, digging through some two metres (six feet) of rubble to leave only an estimated seven metres (23 feet) to go.
Rajput Rai, a drilling expert, told the Press Trust of India that three-person teams are taking turns working at the rock face inside a metal pipe, just wide enough for someone to squeeze through.
While one worker drills, a second scoops up the rubble by hand, and the third places it on a wheeled trolley to be pulled out, Rai said, according to PTI's Tuesday report.
Rescuers have brought in a superheated plasma cutter to slice through submerged metal rods that have repeatedly impeded progress.
Tunnel expert Chris Cooper, who is advising the rescue teams, said Monday he was optimistic that they would break through.
"It depends on how the ground behaves," he told reporters, adding that they may have to cut through heavy-duty girders that had been meant to hold the collapsed roof up.
"We are confident that we can overcome it."
The 41 construction workers have been trapped since November 12 in a tunnel being constructed between the remote towns of Silkyara and Dandalgaon in the Himalayan state of Uttarakhand.
The more than two-week-long rescue operation has been hit by repeated setbacks.
- 'Last hope' -
Efforts have been complicated by falling debris and repeated breakdowns of drilling machines.
Last week, engineers working to drive a metal pipe horizontally through 57 metres (187 feet) of rock and concrete ran into metal girders and construction vehicles buried in the rubble, snapping a giant earth-boring auger machine.
In a separate effort, a drilling machine was brought up to a forested hill above the tunnel on a specially constructed track.
Vertical drilling from that location is now nearly halfway through the 89 metres (292 feet) needed to reach the stranded men, a risky route in an area that has already suffered a collapse.
Digging, blasting and drilling have also begun from the far side of the road tunnel, a much longer third route estimated to be around 480 metres (1,575 feet).
The workers were seen alive for the first time on Tuesday, peering into the lens of an endoscopic camera sent by rescuers down a thin pipe through which air, food, water and electricity are being delivered.
"Our only source of strength is God, as it is the last hope for us," said mother-of-three Musarrat Jahan, whose husband Mohd Sabah Ahmad is a migrant worker trapped inside.
"We have more faith in God than anything", she told AFP by phone from her home in the eastern state of Bihar, one of India's poorest.
Though trapped, the workers have plenty of space in the tunnel, with the area inside 8.5 metres (28 feet) high and stretching about two kilometres in length.
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