Rescue operations intensified at the site in Uttarakhand’s Uttarkashi district where an under-construction tunnel collapsed, trapping 41 workers, PTI reported on Wednesday.

A part of an under-construction tunnel on the Brahmakhal-Yamunotri national highway had collapsed in the early hours of November 12, trapping 41 workers. The tunnel is part of the Char Dham Road Project to build all-weather roads in Uttarakhand.

Rescue personnel on Wednesday inserted wide pipes around 45 metres through the rubble, officials said. They will now have to drill through another 12 metres in order to reach the workers.

Authorities are now expecting to get a breakthrough by Wednesday night or early morning on Thursday, according to The Indian Express.

On Tuesday, rescue workers had established visual communication with the workers and had also established an audio communication channel after sending a microphone and speaker to the other end of a 6-inch supply pipe.

“On this side we are using headphones to talk to them,” Uttarakhand Government Secretary Neeraj Khairwal said. “Using this channel our doctors talked to them and asked for their well being. Some of them complained of constipation and medicines were provided.”

The workers were provided with a walkie-talkie to communicate with the team.

Uttarakhand Chief Minister Pushkar Singh Dhami said that rescue efforts were proceeding swiftly and that he was on his way to Uttarkashi to oversee the operation.

A 53-metre-long and six-inch-wide pipeline was pushed through the rubble of the collapsed tunnel on Monday. The pipe was crucial in sending food and other essential items to the workers trapped inside.

So far rescue workers have inserted seven pipes, including four of 900 mm diameter and three of 800 mm diameter, up to 39 metres through the rubble, former Advisor to Prime Minister and Officer on Special Duty (Tourism) Bhaskar Khulbe told The Indian Express.