The workers, who have been stuck in the motorway tunnel in Uttarakhand state since November 12, are safe and being fed through a pipe, authorities said.
Difficulties with a drilling machine that replaced another machine damaged while breaking through rock caused a halt to digging on Sunday.
Rescuers had been drilling horizontally through the debris towards the trapped workers in the 4.5km tunnel.
Authorities have so far drilled 24 metres through the rock, but it would require up to 60 metres to allow the workers to escape, said Devendra Patwal, a disaster management official.
But after that plan failed, families of those stuck underground are growing more angry.
“I am losing my patience,” said Maharaj Singh Negi, whose brother Gabbar Singh is among the trapped workers. “The officials have not even briefed us about the future plans.”
Government spokeswoman Deepa Gaur said a new machine could be used to drill from the top of the hill that the collapsed tunnel runs through, a method that would take an additional four or five days, she said.
Other alternatives include a perpendicular tunnel with two proposed routes and insertion of a pipe 150mm wide as a lifeline, said Reuters, reporting that it had seen a government document containing the plan.
The Indian Prime Minister’s Office has joined rescue efforts.
Officials from various departments met on Sunday to examine options to try to access the trapped workers and to provide them with food and supplies, the government said.
The Air Force is helping airlift the necessary equipment for the operation and the Army is assisting, the government said. India’s Border Roads Organisation is building an access road to the area where a vertical hole will be drilled to help provide supplies to the trapped workers.
Uttarakhand Chief Minister Pushkar Singh Dhami and Union Minister Nitin Gadkari are scheduled to inspect the site Sunday and to receive updates on the relief work.
The cause of the accident has not been determined, although the hillside region is prone to landslides, earthquakes and floods.