DEHRADUN: Despite a fortnight of arduous efforts by a 200-member strong team of experts and engineers, the 41 workers trapped in a collapsed portion of the Silkyara tunnel in Uttarakhand are yet to see the light of day. Engineers working round the clock to rescue the workers are now mulling the vertical drilling option.
The complexities of the rescue operation that is being carried out on a war footing are constantly challenging the relief team. After the Auger machine was used to drill about 47 metres from the horizontal direction, the pipe-laying operation has been postponed for the time being due to frequent encounters with metallic and hard rock objects inside the tunnel.
However, the National Highways Infrastructure Development Corporation Limited (NHIDCL) is not ruling out the option of horizontal drilling.
"We can't think of switching to vertical drilling before we completely exhaust the option of inserting 800 mm pipes for the rescue," said Colonel Deepak Patil, head of the rescue operation.
According to an official source, "A 1.5-km access road to the top of the tunnel has already been built by the Border Roads Organisation (BRO) as the option of vertical drilling has been on the cards for some time. The platform for launching the drilling machine with markings of drilling points above the tunnel has also been finalised after discussions with GSI, RVNL and ONGC."
"Vertical drilling is a more time-consuming and complicated option that demands more exactitude and caution due to narrower space available on top of the tunnel roof," international tunnelling expert Arnold Dix said.
Rescue authorities have also roped in the THDC, which has started constructing a rescue tunnel from the Barkot end, with four explosions already completed, resulting in a 9.10-metre drift.
Another drill machine is being brought from Hyderabad to further strengthen the rescue operation, Uttarakhand Finance Minister Premchand Agarwal told The New Indian Express.
Minister Agarwal also said, "On the instructions of the government, a BSNL landline facility is being provided near the tunnel so that the families of the workers can talk to them."
Five agencies -- NHIDCL, SJVN Ltd, RVNL, NHAI, and TCIL -- have been assigned specific responsibilities, and are working collaboratively with coordinated efforts for operational efficiency and safe evacuation of stranded labourers.
The 2 km section of the tunnel with completed concrete work, ensuring the safety of the workers, is the focus of the rescue efforts. In this secured portion of the tunnel, electricity and water supply are operational, and provisions, including cooked food and medicines, are being delivered through additional pipelines of 6-inch diameter in addition to an existing 4-inch lifeline.
With the completion of the Silkyara tunnel which is a dream project of Prime Minister Narendra Modi, the distance between the Chardham route will be reduced by 90 minutes and from Dandalgaon to Silkyara on the Yamanotri route by 32 km.
