International Desk

Ambulances were on standby Thursday morning as Indian rescuers dug through the final metres of debris separating them from 41 workers trapped in a collapsed road tunnel for nearly two weeks.

Rescue teams have specially fitted stretchers with wheels, ready to pull out the exhausted men through 57 metres (187 feet) of steel pipe -- once it is finally driven through the final section of the tonnes of earth, concrete and rubble blocking their freedom.

Emergency vehicles and a field hospital stood ready, AFP journalists at the site said, preparing to receive the men who have been trapped since a portion of the under-construction tunnel in the Himalayan state of Uttarakhand caved in 12 days ago.

"We have done rehearsals on how to get people safely out," National Disaster Response Force chief Atul Karwal told reporters Thursday.

"The boys will go in first," he said. "We have put wheels under the stretchers so that when we go in, we can get the people out one by one on the stretcher -- we are prepared in every way."

'Ready to handle it'

After days of painfully slow progress, engineers with a powerful drilling machine made a sudden rapid advance on Wednesday, before teams had to work through the night to cut through metal rods blocking the route.

Drilling resumed Thursday.

"The 10 to 12 metres (32-39 feet) remaining... we don't know what can come up, but we are ready to handle it," Karwal said.

"If everything is alright, tonight this operation will be over," he said, adding that the trapped men were "keeping up their morale".

Uttarakhand Chief Minister Pushkar Singh Dhami said the work was on a "war footing," with a "team of doctors, ambulances, helicopters and a field hospital" all set up.

Rescuers are hoping for a breakthrough within hours, although the government has also repeatedly warned any timelines were "subject to change due to technical glitches, the challenging Himalayan terrain, and unforeseen emergencies."

Inside the Silkyara tunnel entrance, an AFP journalist said the site was a flurry of activity.

'Happiest day'

Worried relatives have gathered outside the site, where a Hindu shrine has been erected, with a priest holding prayers for the safe rescue of the trapped men.

"The day they will come out of the tunnel, it will be the biggest, happiest day for us," said Chanchal Singh Bisht, 35, whose 24-year-old cousin Pushkar Singh Ary is trapped inside.

Rescue efforts have been hampered by falling debris as well as repeated breakdowns of crucial heavy-drilling machines.

In case the route through the main tunnel entrance does not work, rescuers also started blasting and drilling from the far end of the unfinished tunnel, nearly half a kilometre (over a quarter of a mile) long.

Preparations have also been made for a risky vertical shaft directly above.

The workers were seen alive for the first time on Tuesday, peering into the lens of an endoscopic camera sent by rescuers down a thin pipe through which air, food, water and electricity are being delivered.

Though trapped, they have plenty of space, with the area inside 8.5 metres high and stretching about two kilometres in length.

The tunnel is part of Prime Minister Narendra Modi's infrastructure project aimed at cutting travel times between some of the most popular Hindu sites in the country, as well as improving access to strategic areas bordering rival China.

But experts have warned about the impact of extensive construction in Uttarakhand, large parts of which are prone to landslides.