While contact has been established with the workers and they are said to be safe, the Union Ministry of Road Transport and?Highways has said it could another day to extract them. Secretary Disaster Management Ranjit Kumar Sinha who visited the tunnel said the trapped labourers could be rescued by Tuesday night or Wednesday.?

As the officials put the plan in motion to rescue the workers, a field hospital has been set up at the site of the accident and an appropriate number of ambulances have been deployed there to transport the workers for medical examination and treatment.?

Son of Gabbar Singh Negi, one of the workers, on Tuesday got a chance to talk to his father. After their brief conversation, he told that the father said they were okay.

On Sunday, a portion of the tunnel under construction between Silkyara and Dandalgaon on the Brahmakhal-Yamunotri National Highway collapsed.?

Here are the latest updates:

Workers to be extracted via pipes, rescue continues

Large 900 mm diameter pipes and drilling machines arrived at the site on Monday night for evacuation of the 40 trapped workers. Rescuers started preparing a platform for auger machine for horizontal drilling to pass the pipes through the debris right up to the trapped workers. Currently, oxygen and other essential supplies are being provided to the workers through a similar method.?

Such a technique, called 'trenchless' technique, would allow the trapped workers to crawl through the pipes. These pipes would pass through the debris which would not be cleared in its entirety.

"In the first two days, the plan to remove debris using heavy excavator machines, and prevent more debris from falling using the 'shotcrete method', has only been partially successful. Under shotcreting, as soon as debris is removed, concrete is shot at high pressure to prevent more from falling," reported The Indian Express, adding that the new 'trenchless' method is being adopted as the debris that kept falling from the upper part of the tunnel under the 'shortcreting' technique hampered the plan.

The new 'trenchless technique' is minimal invasive way of reaching the workers as it would cause minimum destabilisation to the debris and the tunnel.

"The basic principle behind its operation involves a spiral blade rotating and pushing material away from the hole being drilled. Once drilled, the MS [mild steel] pipes can be pushed through the pile of debris, creating a passage wide enough for those inside to crawl through...The 'trenchless' techniques can be valuable in tunnel collapse rescue operations to access and rescue individuals trapped underground without exacerbating the collapse or causing further harm. These methods offer a way to reach trapped individuals without significant excavation, reducing the risk of further structural instability," reported The Express.

Five expert engineers from the state irrigation department have also arrived at the site to oversee the insertion of pipes into the rubble for the rescue, according to a statement shared by PTI.

In all, around 160 personnel from the National Disaster Response Force (NDRF), State Disaster Response Force (SDRF), Indo-Tibetan Border Police (ITBP), Border Roads Organisation (BRO), Rapid Action Force (RAF), and the state health department are on the spot since Sunday and are engaged in the relief and rescue efforts, according to PTI.

Field hospital set up at site, ambulances deployed

To tackle any emergency health situation, a field hospital has been set up at the site of the accident.

Moreover, ambulances have also been deployed to transport the workers for medical exam and treatment after their extraction.

"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," reported PTI.

Uttarakhand govt forms committee to probe accident

A six-member technical committee headed by Uttarakhand Landslide Minimisation and Management Centre has been set up to look?into the circumstances that led to the partial collapse of the tunnel following a landslide.?

The committee has been mandated to prepare a report on the incident and submit the same to the state government.?

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

Environment experts give warning

Meanwhile, environmentalists warned that such horrific incidents?would continue to happen if ecological concerns were not addressed.??

Former advisor to the State Planning Commission, Harshapati Uniyal, said, "These all-weather roads are a tragedy for Uttarakhand, especially because of the wrong techniques being used for their widening. The river valley alignment cannot be considered safe. If you disturb the slopes, disasters like landslides are inevitable."

Social activist Shivanand Chamoli, who has been vocal on these issues, said considering the sensitivity of the Himalayas, development projects should be examined from every aspect before permission is given. ????

The 40 trapped workers include 15 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.