Atal Tunnel: Everything you must know about longest highway tunnel

The all-weather Atal tunnel inaugurated by Prime Minister Narendra Modi on Saturday will reduce the distance between Manali and Leh by 46 km and the travel time by four to five hours.

It is the longest highway tunnel in the world. The strategically important tunnel is 9.02 km long and it connects Manali to Lahaul-Spiti valley throughout the year. The valley was earlier cut off for about six months every year due to heavy snowfall.

The tunnel is built with ultra-modern specifications in the Pir Panjal range of Himalayas at an altitude of 3,000 metres (10,000 feet) from the Mean Sea Level.

The south portal of Atal Tunnel is located at a distance of 25 km from Manali at an altitude of 3,060 metres, while the north portal (NP) of the tunnel is located near village Teling, Sissu, in Lahaul Valley at an altitude of 3,071 metres.

It is a horse shoe shaped, single-tube double lane tunnel with a roadway of 8 metres and has an overhead clearance of 5.525 metres, officials said.

The tunnel, built at a cost of about Rs 3,300 crore, is extremely significant from the point of view of the country's defence, they said.

The Border Roads Organisation worked relentlessly to overcome major geological, terrain and weather challenges that included the most difficult stretch of the 587-metre Seri Nalah Fault Zone. The breakthrough from both ends was achieved on October 15, 2017.

Talking about the tunnel, a BRO official said it provides a telephone facility at every 150 metre of its stretch, a fire hydrant every 60 metre, emergency exits every 500 metre, turning cavern every 2.2 km, air quality monitors every 1 km, broadcasting system and automatic incident detection system with CCTV cameras every 250 metre.

The Atal Bihari Vajpayee government had taken the decision to construct the strategic tunnel below the Rohtang Pass on June 3, 2000, and the foundation stone for the access road to the south portal of the tunnel was laid on May 26, 2002.

Vajpayee got the idea for constructing the tunnel on a suggestion from his friend Arjun Gopal of Tashi Dobhe village in Lahaul, Himachal Pradesh Chief Minister Jai Ram Thakur had said.

The Modi government decided to name the Rohtang Tunnel as Atal Tunnel in December 2019 to honour the former prime minister who had passed away the previous year.