The horizontal drilling through the rubble to create an escape passage for the 40 workers trapped inside the collapsed Silkyara tunnel has resumed.
A press release issued in the evening by the Union Ministry of Road Transport and Highways in Delhi said the NHIDCL has resumed the horizontal boring operation from the Silkyara end that involved an auger machine.
The boring had to be stopped after the huge America-made auger machine hit a hard boulder on Friday, triggering vibrations that forced rescuers to put the operation on hold due to safety concerns.
According to Mahmood Ahmed, additional secretary with the Road Transport ministry, the 900-mm steel pipes will be replaced with 800-mm pipes. "Six-metre sections of 900-mm wide steel pipes had been pushed 22 metres through the debris before the work stalled. Now 800-mm pipes will be inserted, making the process easier. When the pipe reaches the 22-metre point, drilling will resume," he said.
"Progress from the 22-metre point to the 45-metre mark will be the most critical. If the drilling goes smoothly, it will take 30 to 40 hours," Mahmood said.
Meanwhile, the vertical drilling to create a shaft on top of the hill will also continue but experts believe horizontal drilling is safer. International tunnelling expert Arnold Dix, who is at the site, said vertical drilling demanded precision. "While drilling from the top, even a small mistake could mean missing the tunnel," he said.
As for vertical drilling, the plan was to bore more than 80 metres vertically from above the tunnel to reach the two-kilometre built-up stretch where the workers are now trapped. Some of the heavy machinery for the purpose had arrived at the disaster site after facing a brief hiccup. The machines were stuck in the narrow road and the passage had to be cleared. A road has also been constructed to haul a 75-tonne machine up the hill.
Meanwhile, all the workers are safe and doing well. They were served veg pulao, matar-paneer, and chapatis slapped with butter for dinner on Tuesday night through a food pipe stuck through the collapsed part of the structure.
The dinner, prepared under the doctor's supervision with less oil and spices to make it easily digestible, was supplied to the workers in 150 packets, cook Sanjit Rana said. Fruits were sent to them earlier in the day, he said.