Rescue personnel renewed their efforts on Thursday to save 40 men trapped inside a partially collapsed under-construction tunnel in Uttarakhand as they used an advanced drilling machine to cut through rocks and debris, reported Reuters.

The tunnel on the Brahmakhal-Yamunotri national highway collapsed in the early hours of Sunday, leaving 40 workers trapped inside. It is part of the Char Dham Road Project to build all-weather roads in Uttarakhand.

On Monday, rescue workers had been able to cut through around 20 metres of debris out of a total of 55 metres to 60 metres. However, soil caved in the area again. This reduced the excavated portion to 14 metres.

Colonel Deepak Patil, who is heading the rescue operation, said on Thursday that “there was a high chance of plan B being successful”, reported The Indian Express.

Rescue personnel were now using “state-of-the-art, American-made horizontal dry drilling equipment”, Patil said. He said that it was just a matter of hours for the operation to be completed, but added that he could give an exact timeline as the speed of the relief work could change.

Union Minister VK Singh said that officials are aiming to finish the operation within two to three days, NDTV reported. “It could happen earlier as well but we are keeping 2-3 days as the outer limit in case any other problems arise,” he said.

Singh said that the government is taking the advice of foreign as well as Indian experts. “I have spoken to the labourers,” he added. “Their morale is high and they know that the government is making efforts to rescue them.”

With about 100 hours of being trapped, the trapped workers on Wednesday said that they were facing health issues, reported The Indian Express.

Doctor BS Pokhriyal, a general physician, spoke to the workers through the pipe that is being used to supply oxygen. After his conversation, Pokhriyal said that the workers complained of vomiting, headache, anxiety and gastritis.

To counter this, medications for vomiting as well as provisions such as dry fruits, puffer rice and chickpeas were sent in. Besides this, other essential medicines, multivitamins, glucose and dry fruits are being delivered.