The ongoing operation to rescue 41 workers trapped inside the collapsed Silkyara-Polgaon tunnel in Uttarkashi was stopped on Saturday night as the drilling machine was obstructed by heavy boulders under the debris. New machine brought from Indore is yet to resume drilling.

Officials engaged in rescue operations confirmed that escape passage work was halted in the night for safety reasons as drilling could not move forward beyond 24 meters.

According to the officials, the obstructed machine started shaking the earth around it and the tunnel developed cracks.

Only four 900 mm steel pipes were pushed inside the debris while efforts to connect the fifth pipe failed as the machine could not drill further for obstruction caused most likely by a big boulder or possible machine buried under the debris.

“The drilling work for making an escape passage to reach the workers had to be stopped on Friday night due to safety reasons. Some safety issues cropped up in the night as the drilling machine was unable to move forward due to physical obstructions,” District Magistrate Abhishek Ruhlea told The Statesman.

“It’s difficult to say exactly about the identity of the obstruction. Only investigation can reveal it,” he said, informing that the “second machine airlifted from Indore is being staged to resume the escape passage work again. Other measures are also being weighed to bring out the trapped workers.”

The stranded workers were still more than 40 meters away from the reach of rescue teams when the escape passage work was halted.

Officials said that obstruction was so hard that further drilling with a 1750 horse power auger machine had shaken the earth around it. It also ran the risk of further debris fall.

The second machine airlifted from Indore is being assembled at Silkyara village tunnel collapse site and drilling work will resume after that.

Earlier the machine landed at Dehradun Based Jollygrant Airport on Saturday 1.30 am. It was shifted to the site early in the morning.

Officials present on the ground informed that a team of experts from Hyderabad based National Geophysical Research Institute (NGRI) is also being called to detect the obstacle and hammer out possible measures to overcome the same.

As many as 41 workers have been trapped in the collapsed tunnel for more than six days since the incident took place on November 12.