Silkyara: The rescue operation to take out 41 workers, trapped since November 12 in the 4.5-km collapsed under-construction tunnel in Uttarakhand, will take much longer.

"Auger drilling started at 0045 Hrs on 22.11.2023 was halted due to metallic object (Lattice girder rib) being encountered in front of the pipe and the pipe could not be inserted further," the government said in a statement.

The operation will have to be carried out for an extended period as the rescuers decided to switch to manual boring after the heavy drill deployed to clear the 60 meters of debris was damaged.

"The timelines provided are subject to change due to technical glitches, the challenging Himalayan terrain, and unforeseen emergencies," the Ministry of Road Transport said in a staement on Sunday, highlighting that the operation is likely to deviate from specific timeframes mentioned by officials from time to time.

Five agencies—ONGC, SJVNL, RVNL, NHIDCL, and THDCL—have been assigned specific responsibilities, working collaboratively with occasional task adjustments for operational efficiency, it said.

Following the damage, the last 10-15 meters would have to be broken with hand-held power tools.

Officials assure their safety, providing them with light, oxygen, food, water, and medicines.

A drilling machine, known as an auger, was damaged on Friday while being extracted from the 47-meter pipe intended to rescue the workers, after hitting an obstacle.

The machine drilled a horizontal passage of 46.8 metres into the rubble out of a total estimated length of 60 metres.

On hitting the hurdle, its rotary blades got stuck. A steel chute, assembled in sections, had been bored to the point, where the rotary blades met the obstruction.

Around 20 meters of the auger within the chute has been removed, Dhami told reporters. To deal with the remaining 25 meters, a plasma cutter is being transported by air from Hyderabad.

The labourers have been trapped in a 400-metre buffer zone of the unfinished main tunnel since November 12 when a portion of the 4.5-km tunnel on the Brahmakhal-Yamunotri National Highway collapsed.

The tunnel - meant to join Silkyara and Dandalgaon in Uttarkashi - is a part of the Char Dham project.

The cause of the tunnel collapse has not been revealed by authorities.

Located in the Himalayas, the area is susceptible to landslides, earthquakes, and floods.

However, a member of a panel of experts investigating the incident told Reuters on the conditions of anonymity the tunnel lacked an emergency exit and was constructed on a geological fault.

However, International Tunneling Expert, Arnold Dix told news agency ANI, "It shouldn't have an escape tunnel at this stage because normally you don't expect them to collapse. So, normally around the world, we don't build our tunnels anticipating them to collapse like this. What we do is we put escape tunnels at the end. So, if there is an incident, users can escape. My understanding is that the final design has that but when we are constructing, we normally don't do that..."

On Saturday, Uttarakhand Chief Minister Pushkar Singh Dhami said the damaged drilling machine would be withdrawn by Sunday morning so that manual drilling could start.

Syed Ata Hasnain, a member of the National Disaster Management Authority overseeing the rescue efforts, has indicated that the operation is growing "more complex." He stated that the procedure would slow down in comparison to the initial drilling phase when the auger was employed.