“Vertical drilling started at around 12 noon. 86 meters of digging is required to reach the trapped workers and make an escape passage. 15 metres have already been drilled,” NDMA officials said.

Multiple agencies have joined the rescue efforts over the past two weeks. The Indian Air Force became part of the team on Sunday as it flew in critical DRDO equipment to Dehradun.

The trapped workers had been ‘hours away’ from rescue on Thursday as the auger machine broke down repeatedly. Rescuers were forced to look for alternatives after the machine’s blades got stuck inside the rubble and a complete disengagement became necessary for work to continue. A plasma cutter has since been flown in from Hyderabad to remove parts of the auger machine stuck in the rubble.

While vertical drilling is considered the second best option available to rescuers, there are risks associated with the process. It can cause vibrations in the already fragile mountain and had previously been tagged as ‘dangerous’ by officials. International tunnelling expert Arnold Dix – who has roped in the rescue project – however said on Sunday that there was no chance of any further collapse in the area where the incident took place.

Rescuers now have to drill through 86 metres of earth and rubble before breaking the tunnel crust that lies underneath. 

The workers had been trapped on November 12 due to a muck fall in a 60-metre stretch on the Silkyara side of the tunnel. The route is being developed to connect Silkyara to Barkot in Uttarakhand. The Barkot end of the tunnel remains closed as work had not yet started on that side.

Officials are executing as many as six plans to rescue the workers. However the best option so far remains horizontal drilling – under which 47 meters of drilling have been completed.

(With inputs from agencies)

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Updated: 26 Nov 2023, 05:59 PM IST