Rescue workers on Tuesday began the process of inserting wide steel pipes through the rubble of the collapsed under-construction tunnel on the Char Dham route to bring out the 40 labourers trapped inside for two days, officials said.

Drilling to insert the pipes has begun with the help of an 'auger machine', Uttarkashi District Magistrate Abhishek Ruhela told reporters.

"If everything goes as planned, the trapped labourers will be evacuated by Wednesday," he said after visiting the tunnel and taking an update on the operations from officials at the site.

Most of the day went into preparing a platform inside the tunnel to position the auger machine for drilling through the rubble.

The drilling machine and the pipes arrived at the site early on Tuesday.

The plan is to push through both 800- and 900-millimetre diameter sections of mild steel pipes -- one after the other -- into the rubble using drilling equipment and create an escape passage for the workers who, the officials said, are safe and being provided with oxygen, water, food packets and medicines through tubes.

There are eight 900-millimetre diameter pipes with a length of six metres each and five pipes of 800-millimetre diameter of the same length, the State Emergency Operation Centre said.

"According to the latest update, all 40 labourers trapped inside are safe and sound," Superintendent of Police (Uttarkashi) Arpan Yaduvanshi told reporters after a visit to the site.

He said some medicines have been supplied as one of the trapped workers was feeling nauseous.

The son of Gabbar Singh Negi, one of the trapped labourers, was allowed to speak to his father for a few seconds on Tuesday.

"He said they are safe. He asked us not to worry," Akash Singh Negi told PTI.

A local priest was asked to perform a puja for the early and safe evacuation of the trapped workers.

A part of the tunnel being built between Silkyara and Dandalgaon on the Brahmakhal-Yamunotri National Highway caved in on Sunday following a landslide. The 30-metre collapsed section is 270 metres from the mouth of the tunnel from the Silkyara side, the State Emergency Operation Centre in Dehradun said.

Disaster Management Secretary Ranjit Kumar Sinha earlier said the authorities had set a target of rescuing the trapped labourers by Tuesday night or Wednesday.

Navyuga Engineering Company Limited official GL Nath appealed to everyone not to enter the tunnel and disrupt the rescue efforts.

"Only those whose services or help is needed in the ongoing rescue operations should enter the tunnel. Local political leaders are disturbing us a lot by frequenting the tunnel. I appeal to them not to do so. Our priority is to safely evacuate the trapped workers," he said.

An expert team of five engineers from the irrigation department is on the spot to oversee the insertion process of the mild steel pipes through the rubble, the State Emergency Operation Centre said.

A team of 160 rescuers from the National Disaster Response Force, State Disaster Response Force, Indo-Tibetan Border Police, Border Roads Organisation, Rapid Action Force and the health department have been on the spot since Sunday, working to reach the trapped workers.

Contact is being maintained with the trapped labourers and the assurance that a huge rescue operation is being carried out by various agencies to evacuate them has also boosted their morale, National Highways & Infrastructure Development Corporation Limited (NHIDCL) Executive Director Col (Retd) Sandip Sudehra said.

The NHIDCL is the agency engaged in building the tunnel.

Uttarkashi's Chief Medical Officer RCS Panwar said a six-bed temporary hospital has been set up near the tunnel and 10 ambulances with medical teams stationed to provide immediate medical care to the trapped workers after their evacuation.

According to a list of the trapped workers issued by the District Emergency Operation Centre, 15 are from Jharkhand, eight from Uttar Pradesh, five from Odisha, four from Bihar, three from West Bengal, two each from Uttarakhand and Assam, and one from Himachal Pradesh.

A team of experts headed by the Uttarakhand Landslide Minimisation and Management Centre director are examining the affected part of the tunnel and the hill above to ascertain the reasons behind the cave in, an official statement said.

The team also includes scientists and officials from the Uttarakhand State Disaster Management Authority, Geological Survey of India, Central Building Research Institute, IIT-Roorkee and the Wadia Institute of Himalayan Geology.

Chief Minister Pushkar Singh Dhami is constantly taking updates on the progress of rescue operations, the statement said.

He held a meeting with senior officers at his residence and asked them to coordinate with officials present on the spot and provide them with relief materials at the earliest.

The proposed tunnel, which is part of the Char Dham road project, will reduce the journey from Uttarkashi to Yamunotri by 26 kilometres.

Environmental experts have warned that horrific incidents such as this will continue to happen if ecological concerns are not addressed.

Ravi Chopra, who last year resigned as chairman of a Supreme Court-appointed high-powered committee on the Char Dham all-weather road project, said it is necessary to first address the ecological concerns for development in the Himalayas.

"Sustainable development demands approaches that are both geologically and ecologically sound. Unless this balance is achieved, such horrific incidents will continue to happen," Chopra told PTI in Dehradun.

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