Drilling at the collapsed Silkyara tunnel to evacuate 41 workers trapped inside for 12 days was yet resume Friday evening, a day after it was put on hold following a snag.

Officials said in the afternoon that technical issues have been sorted and the drilling was set to resume in a couple of hours. But till evening there was no announcement that the auger machine had begun drilling through the remaining stretch of about 12 metres.

A ground penetrating radar has indicated that there are no metal hurdles up to five metres ahead of the passage drilled so far, Neeraj Khairwal, the state’s nodal officer for the multi-agency rescue effort said.

Simultaneously, sections of steel pipes were being laid into the drilled passage.

Once this process is over, National Disaster Response Force (NDRF) men would pull out the trapped workers through this escape chute, one by one.

Over the night, officials said, the auger machine’s platform was strengthened with quick-settling cement.

Workers went over 45 metres inside the passage to cut off the damaged 1.2 metre front end of the pipe -– an operation that took several hours. The portion of the pipe had bent after hitting a hurdle.

A damaged portion of the auger’s blade was also repaired.

The machine had drilled up to 48 metres of the estimated 57-metre stretch of the rubble on Thursday, when the operation stalled.

As the rescue workers prepared to resume the drilling, the steel pipe had been pushed through up to 46.8 metres, officials said. Only two more six-metre sections of steel pipe needed to be inserted to reach the trapped workers.

In Delhi, National Disaster Management Authority (NDMA) member Syed Ata Hasnain told reporters that if there are no obstacles, the auger machine should be able to drill about four or five metres in an hour.

It takes additional time to weld sections of the steel pipe together as they are pushed into the drilled passage. The NDRF operation that will begin once the chute is ready is expected to take about three more hours.

Officials warn that unforeseen hurdles can crop up anytime.

Earlier in the morning, former advisor to the Prime Minister's Office Bhaskar Khulbe had said the boring through the rubble with an auger was likely to resume by 11.30 am.

“We have 12-14 metres more to go. And I hope if all goes well we might conclude the operation by Friday evening," he had predicted.

Garhwal range IG KS Nagnyal told PTI that arrangements are in place to take the rescued workers to medical centres under police escort through a “green corridor” Road Transport and Highways Minister V K Singh, who has been camping in Uttarkashi since Thursday, visited the Silkyara site to take stock of the rescue operation.

Chief Minister Pushkar Singh Dhami has been staying at nearby Matli and visited the disaster site again on Friday. Prime Minister Narendra Modi talked to Dhami once again for updates.

The NDRF conducted a mock drill at the site. An NDRF jawan went into the escape passage, pushing a wheeled stretcher tied to a rope. He was then pulled back.

He said there was enough room inside the pipe and he had no difficulty breathing during the exercise.

Forty-one ambulances are stationed outside the tunnel to rush workers after their evacuation to Chinyalisaur community health centre where a separate ward has been set up with 41 oxygen-supported beds for them.

Similar arrangements have also been made at the Uttarkashi district hospital.Trauma and ICU beds have also been readied for them at AIIMS, Rishikesh where they could also be airlifted if required.

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