Rescue work at the collapsed Silkyara tunnel in Uttarakhand was virtually on hold Sunday as the agencies involved in the effort set themselves up for the next stage -- adopting multiple approaches to reach the 41 men trapped inside for a week.

Officials said a road to the top of the hill has been laid in a single day for digging a vertical shaft down into the tunnel.

Also, the Tehri Hydroelectric Development Corporation was set to begin “micro tunneling” Sunday night from the Barkot end of the under-construction tunnel on the Char Dham route, part of which collapsed on November 12.

Boring through the debris of the collapsed 60-metre stretch from the Silkyara end was put on hold Friday afternoon when the American-made heavy-duty auger machine encountered a hard obstacle after about 22 metres.

The setback forced a rethink on Friday. Officials drew up a series of alternative plans to reach the workers trapped inside the under-construction tunnel.

But after a visit to the site Sunday, Union Road Transport Minister Nitin Gadkari said boring horizontally through the debris with the huge auger machine appeared to be the best bet. He anticipated a breakthrough two and a half days.

A media brief issued in Delhi said this drilling would begin again Monday, after safety arrangements for rescue workers are put in place.

By Sunday evening, rescue workers had pushed in a six-inch wide tube up to 39 metres into the rubble. Once it cuts across the collapsed stretch, the trapped workers would be sent food and water through this pipe as well.

A smaller four-inch wide “compressor pipe” already runs through the debris and is being used to send in food, water, oxygen and medicines, officials said.

The stretch in which the workers are trapped is about two kilometres of the built-up portion of the tunnel and is 8.5 metres high. There is electricity and water available, a press release said.

The Rail Vikas Nigam Limited has begun work on a vertical pipeline for supplying essential items after the completion of the approach road to the top of the hill.

"Saving the trapped workers and evacuating them at the earliest is the biggest priority," Gadkari told reporters at Silkyara after a meeting with the experts there. "Preparations are underway to restart the auger machine and resume drilling and pipe-laying at the tunnel," he said.

Gadkari said the auger machine had worked well through the soft soil but there were vibrations in the tunnel when it encountered a hard object. This posed a danger to the safety of the rescue workers.

"Though I am no technical expert, in the given circumstances horizontal digging seems the best option. If the auger machine does not encounter any obstacles it might reach the trapped workers in two and a half days," he said.

Uttarakhand Disaster Management Secretary Ranjit Kumar Sinha said the minister has suggested that there could be space between the top of the debris and the tunnel roof, and this could be explored by robots to see if another pipe for life support could be pushed through.

Road Transport and Highways Secretary Anurag Jain said multivitamins, antidepressants and dry fruit are being provided to the trapped workers.

"Fortunately, there is light inside because the electricity is on. There is a pipeline, and so water is available. There is a four-inch pipe that was used for compression. Through it we are sending food from day 1," he said.

The multiple-pronged approach now being adopted follows a series of setbacks after a portion of the Silkyara-Barkot tunnel collapsed the previous Sunday morning, blocking the way out for the worker who were ending the night shift.

When using earth-moving equipment failed, an auger machine was brought in. When this too didn’t work, the larger American-made drilling machine was airlifted by the IAF from Delhi.

A similar machine was also dispatched from Indore in case a replacement was needed. The vertical drilling equipment arriving next is too big to be hauled by air and will be brought to the site by road, the authorities said.

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