NEW DELHI — Indian Prime Minister Narendra Modi inaugurated the Atal Tunnel in Rohtang, the world's longest highway tunnel above 10,000ft, on Saturday. At the inauguration, Modi was accompanied by Defense Minister Rajnath Singh and Chief Of Defense Staff Gen. Bipin Rawat.

Calling the opening of the Atal Tunnel a historic moment, Modi said that it will be a lifeline for people of Leh and Ladakh.

The strategically important all-weather tunnel, built by the Border Roads Organization, reduces the distance between Manali and Leh by 46 km and the travel time by four to five hours.

The 9.02-km tunnel connects Manali to Lahaul-Spiti valley throughout the year, the Prime Minister's Office has said, noting that the valley was earlier cut off for about six months every year due to heavy snowfall.

"Fulfilling Atal Ji's dream of top quality infrastructure. Will be in Himachal Pradesh tomorrow to dedicate the #AtalTunnel in Rohtang to the nation. This is an iconic infrastructure project built at a height of 10,000 feet," Modi tweeted on Friday.

"The #AtalTunnel will solve a major problem of connectivity in the region. It has several salient features and will further 'Ease of Living' for local citizens. Will also join public programmes in Sissu in Lahaul Spiti and at Solang Valley," he said in another tweet.

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

K.P. Purushothaman, chief engineer, Border Roads Organization (BRO) said the hard work by BRO in these many years has paid off and it is a very "proud moment" for everyone.

"This is a very proud moment not only for BRO but for the whole country. The hard work put in by BRO in the last 10 years is reaching the final stage. This tunnel is an example of Atmanirbhar Bharat," Purushothaman told ANI.

The South Portal (SP) of Atal Tunnel is located at a distance of 25 km from Manali at an altitude of 3,060 meters, while the North Portal (NP) of the tunnel is located near village Teling, Sissu, in Lahaul Valley at an altitude of 3,071 meters.

It is horseshoe-shaped, single tube double lane tunnel with a roadway of eight meters. It has an overhead clearance of 5.525 meters. Also, it is 10.5-meter wide and has a 3.6 x 2.25 meters fire-proof emergency egress tunnel built into the main tunnel itself.

"There are 18 egress tunnels where after every 500 meters there is an opening in case of emergency. If any fire incident happens so the first thing is how the people trapped are to be rescued. For that, there is an entry at every 500 meters. The tunnels are clearly marked and one can easily find out where is the egress tunnel," Purushothaman said.

Atal Tunnel has been designed for traffic density of 3,000 cars per day and 1,500 trucks per day with a max speed of 80 km/hr. It has the state of the art electromechanical system including semi transverse ventilation system.

The tunnel has ample safety features built into it including telephone connections at every 150 meters for emergency communication, fire hydrant mechanisms at every 60 meters, auto incident detection system with CCTV cameras at every 250 meters, air quality monitoring at every one km, evacuation lighting/exit signs and broadcasting system throughout the tunnel among others.

Speaking to ANI, S Paramasivan, managing director, AFCONS, which was the main construction company for the tunnel, said it is of very great importance both from the national defense angle and also from the international arena because this is the longest tunnel at this altitude in the world.

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

Officials said the BRO worked relentlessly to overcome major geological, terrain and weather challenges that included the most difficult stretch of the 587-meter Seri Nalah Fault Zone. The breakthrough from both ends was achieved on Oct. 15, 2017.

The Union Cabinet decided in 2019 to name the Rohtang Tunnel as Atal Tunnel to honor the contribution made by the former prime minister. — Agencies