Rescuers in Himachal Pradesh's Bilaspur district were set to enter a tunnel on Monday to rescue two men who have been trapped more than 40 metres underground for more than a week.
A team from the National Disaster Response Force (NDRF) completed drilling work on the collapsed tunnel on Monday morning, paving the way for rescuers to move inside.
On September 12, three workers of the Himalayan Construction Company were trapped in Tunnel Number 4 being built for the Kiratpur-Nerchowk four-lane project after a cave-in blocked the entrance with tonnes of earth and boulders. The 1.2-kilometre tunnel, a project worth Rs 82 crore, had been dug 275 metres when it collapsed 80 metres from the mouth.
Rescuers first made contact with Satish Tomar and Mani Ram, two of the trapped workers, on September 17 and food and water were dropped during the week after engineers drilled a thin 47-metre (154-foot) shaft down to the roof of the tunnel.
A remote camera and microphone were lowered on Saturday, allowing rescuers to speak to Tomar and Ram, who said they were uninjured. The fate of third worker, Hirday Ram, is uncertain since there has been no contact with him so far.
The National Disaster Response Force (NDRF) has brought advanced sensors to trace Ram.
Using heavy machinery, engineers have spent days trying to dig a wider shaft to allow rescuers to be lowered down into the tunnel, which is part of a highway construction project.
A 50-member team of engineers, technical supervisors, drilling experts and geologists from Sutlej Jal Vidyut Nigam Limited (SJVNL), Border Roads Organisation (BRO), and Himachal Pradesh Power Corporation Limited (HPPCL) is at work to dig a 1.2-metre-wide hole till the tunnel roof to send in an NDRF team that will make a passage beneath through the concrete ceiling and iron ribs.
But efforts have been frustrated by mechanical breakdowns, NDRF commanding officer Jaideep Singh said from the site in Bilaspur district.
The heavy-duty hydraulic rig positioned at the site three days ago had broken down on Friday night first, but the work had resumed on Saturday. Drilling work on the vertical cavity again came to a halt when the machine broke down on Saturday night and could not be repaired till late afternoon, even as a part was shipped from Delhi overnight.
On Sunday, another technical glitch forced the rescue operation to be put off, prolonging the wait for the workers, who are trapped for more than 180 hours now. Continuous rain since early morning and water ingress in the shaft dug to pull out the trapped men added to the difficulty.
"Engineers are trying to sort out the technical problem. The construction company has deployed two more boring machines on the site," said Bilaspur deputy commissioner Mansi Sahay Thakur.
"Rescue will resume as soon as the machine is fixed," she said.
She added rain and water ingress were not a big problem, as the site had adequate drainage and waterproofing and an engine had been deployed to drain out water from the shaft.
A rescue operation through the horizontal route is on simultaneously but slowed down by a wall of more than 60 metres of debris.
NDRF's Singh said completing the shaft was critical to the success of the operation, and once this task was over, his men could reach the survivors.
Along with the rescuers, a team of doctors is also on a standby at the surface.
Dr Arvind Chopra, who is providing medical assistance in the rescue operation, told Hindustan Times that as soon as the workers will be pulled out, the doctors will examine them on the spot depending on their condition.
"We will check their blood pressure, oxygen-carrying capacity of their blood, sugar level, apart from pulse examination. We have also brought blankets, which will be given to them if their body temperature is below normal," said Dr Chopra.
He said living in the dark for so long can have a psychological effect on a person but added since they are acclimatised to such conditions, so there is a rare chance of it.
"We will allow one family member to meet them and they will be taken to the hospital as some more medical examination will be needed," he added.