Vertical drilling of 19.2 metres was done on Sunday to create an alternative escape route for the 41 workers trapped inside the collapsed tunnel in Silkyara here for two weeks, an official said.
Drilling to create a vertical pathway from the top of the hill above the collapsed tunnel began on Sunday, a day after an auger machine carrying out horizontal drilling broke down.
Rescuers have to drill down 86 metres from above to reach the trapped workers.
Vertical drilling has gone up to 19.2 metres so far, NHIDCL MD Mahmood Ahmed said at a press briefing in Silkyara on Sunday evening.
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"The exercise is going on smoothly and if it goes like this without facing obstructions, we can hope to finish it in four days by November 30," he said.
On Saturday, the auger machine's blades got stuck inside the rubble, hindering the multi-agency rescue effort that began on November 12 when a portion of the under-construction tunnel on Uttarakhand's Char Dham route collapsed following a landslide, trapping the 41 workers inside.