The 9.02 Km long tunnel connects Manali to Lahaul-Spiti valley throughout the year. Earlier, the valley was cut off for about 6 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 3000 Mtrs (10,000 Feet) from the Mean Sea Level (MSL).
The South Portal (SP) of the Atal Tunnel is located at a distance of 25 Km from Manali at an altitude of 3060 Mtrs, while the North Portal (NP) of the tunnel is located near the village Teling, Sissu, in Lahaul Valley at an altitude of 3071 Mtrs.
It is a horseshoe-shaped, single tube double lane tunnel with a roadway of 8 Mtrs. It has an overhead clearance of 5.525 Mtrs. It is 10.5-meter wide and has a 3.6 x 2.25 Mtrs fireproof emergency egress tunnel built into the main tunnel itself.
Atal Tunnel has been designed for a traffic density of 3000 cars per day and 1500 trucks per day with a maximum speed of 80 km/hr. It has a state-of-the-art electromechanical system including semi transverse ventilation system, SCADA controlled firefighting, illumination, and monitoring system.
The historic decision to construct a strategic tunnel below the Rohtang Pass was taken on June 03, 2000, when late 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.
The Border Roads Organisation (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 October 15, 2017.
The Union Cabinet met under the chairmanship of Prime Minister on December 24, 2019 and decided to name the Rohtang Tunnel as Atal Tunnel to honour the contribution made by former PM Atal Bihari Vajpayee.