Atal Tunnel : Prime Minister Narendra Modi is scheduled to inaugurate the Rohtang Tunnel, also known as the Atal tunnel at Rohtang on the morning of Saturday, i.e., October 3. The Rohtang tunnel, named after former Prime Minister late Atal Bihari Vajpayee, was slated to be completed by May 2020, according to an IE report. However, the coronavirus pandemic-induced lockdown caused the project to be delayed by a few months. The tunnel holds strategic importance as it poses an alternative to the Rohtang Pass and reduces the travel time between Manali valley and Lahaul-Spiti Valley significantly, hence providing a boost to the movement of armed forces. Rohtang tunnel or the Atal tunnel is also to be the longest highway tunnel in the world at a height of above 10,171 feet.

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Features of Atal Tunnel

At 9.02 km length, the tunnel will be one of the longest road tunnels in India and is expecting to reduce the distance between Manali and Leh by 46 km. The tunnel is at an elevation of 3,100 metres (10,171 ft) whereas the Rohtang Pass is at an elevation of 3,978 metres (13,051 ft).

Construction Techniques

Operations during the construction of tunnel was dividing into four main phases :-

• Drilling
• Blasting
• Loading
• Transport and Excavating and Landscaping.

All the process are explaining are below :

1. Drilling the tunnel was carring out using computer-controlled drilling jumbos as well as traditional drilling and blasting. To make sure that the tunnel sections met more than 10km into the rock and 1000 metres under the mountain, it was important that the drilling and blasting work were carried out with great precision.
2. Blasting was conducted using approximately 100 holes, 45 – 51mm in diameter and 5.2 metres deep, drilled for each blast.
3. Wheel-mounted loaders were used for loading and transport in the tunnel. The excavated materials were transported out of the tunnel using dump trucks.
4. The disposal of 2.5 million cubic metres of excavated rock from the tunnel was one of the greatest challenges in planning the tunnel.

Another parallel tunnel of 3.3×2.2 metres, an emergency passage of sorts, has been constructed under the Atal Rohtang tunnel with staircases at every 500 metres connecting it to the main tunnel. Three thousand cars and 1,500 trucks can pass through the Atal Tunnel at 80 km per hour.

Challenges Faces During The Construction

• The major challenges during the task is heavy snowfall in Winter.
• Rohtang pass closes during the winter, the north portal was not available during the winter and the excavation done only from the south portal in winters.
• The other most difficult situation is disposing of excavate rocks and sand almost more than 8,00,000 cubic meter.
• Unstable rocks due to slow process of blasting and digging.
• Major incident happen is cloud-burst and flash flood on 8 August 2003. They killed 42 labourers who were building the temporary access road.