Uttarakhand Tunnel Rescue - What led the rescue team to success ? Hits and Misses
The 17-day effort that culminated on tuesday evening with the rescue of 41 workers trapped in the under-construction Silkyara-Barkot tunnel marked the completion of a mission that had its ups and downs. The 17-day effort that culminated on tuesday evening with the rescue of 41 workers trapped in the under-construction Silkyara-Barkot tunnel marked the completion of a mission that had its ups and downs.
On november 12, authorities from the National Disaster Relief Force (NDRF) began the rescue effort by scooping up the rubble with excavators. The robots had sliced through 21 of the 57m of rubble in a single day. But within a day, a new cave-in knocked off a third of those advances and piled seven meters more rubble to the wall.
On november 14, officials began looking for a new approach amid concerns that the ongoing use of excavators may cause further harm in an already dangerous scenario.
They used auger machines, which look like corkscrews with rotating blades at the front, to drill through the rock and concrete wall.
Authorities continued to place 800-900mm-wide steel pipes that would serve as exits for the trapped men while the machine sliced through the rock. However, after only two yards, the machine snapped against the hard stone.
Then, on november 15, officials switched to a more powerful US-made auger machine, which was brought in from Delhi. It arrived at Uttarkashi the next day and had removed 22m of debris by november 17. But this machine, too, became entangled, its blades damaged by the hard wall.
Despite this, officials continued to use the auger machine while planning alternate routes: drilling vertically in two areas to approach the tunnel from above, via a hill; drilling horizontally from the side of the hill; and digging in from the opposite end of the tunnel.
More agencies were enlisted into the operation at this stage, including ONGC, which specialized in hydel missions.
Meanwhile, rescuers proceeded to push in pipes to provide food, medications, and other necessary supplies to the trapped workers, as well as telephone cables and an endoscopic camera to make video communication. The auger machine dug away, occasionally providing encouraging indicators for the rescue, raising expectations among officials and personnel. At times, the machine appeared to wilt in the data-face of the obstacle.
On november 12, authorities from the National Disaster Relief Force (NDRF) began the rescue effort by scooping up the rubble with excavators. The robots had sliced through 21 of the 57m of rubble in a single day. But within a day, a new cave-in knocked off a third of those advances and piled seven meters more rubble to the wall.
On november 14, officials began looking for a new approach amid concerns that the ongoing use of excavators may cause further harm in an already dangerous scenario.
They used auger machines, which look like corkscrews with rotating blades at the front, to drill through the rock and concrete wall.
Authorities continued to place 800-900mm-wide steel pipes that would serve as exits for the trapped men while the machine sliced through the rock. However, after only two yards, the machine snapped against the hard stone.
Then, on november 15, officials switched to a more powerful US-made auger machine, which was brought in from Delhi. It arrived at Uttarkashi the next day and had removed 22m of debris by november 17. But this machine, too, became entangled, its blades damaged by the hard wall.
Despite this, officials continued to use the auger machine while planning alternate routes: drilling vertically in two areas to approach the tunnel from above, via a hill; drilling horizontally from the side of the hill; and digging in from the opposite end of the tunnel.
More agencies were enlisted into the operation at this stage, including ONGC, which specialized in hydel missions.
Meanwhile, rescuers proceeded to push in pipes to provide food, medications, and other necessary supplies to the trapped workers, as well as telephone cables and an endoscopic camera to make video communication. The auger machine dug away, occasionally providing encouraging indicators for the rescue, raising expectations among officials and personnel. At times, the machine appeared to wilt in the data-face of the obstacle.