Atal tunnel, an all weather tunnel built under the Rohtang pass was inaugurated on the Leh-Manali highway. This tunnel is intended to reduce the distance of travel towards Leh by around 46 km and the time by 4-5 hours. Another route to Leh is through Zoji La pass which gets blocked by snow for around four months every year. The Atal tunnel has been touted as one of its kind highway construction in the world at above 10000 feet of altitude and 9.02 km in length. It has been built with ultra-modern specifications in the Pir Panjal range of Himalayas. The Rohtang pass under which the Atal tunnel has been built provides an important divide between the Lahaul and Spiti Valleys with a Buddhist cultural touch and the Kullu valley with a Hindu cultural domain. The pass in which the Atal tunnel is situated lies in the watershed region between the Beas and Chenab river basins.

The newly inaugurated Atal Tunnel is of horse shoe-shape, single tube & double lane format. It has a roadway of 8 metres and an overhead clearance of 5.525 metres. The tunnel has been designed for a traffic density of around 1500 trucks and 3000 cars per day, each of which can travel at a maximum speed of around 80 kmph.

The north portal of the tunnel is at an altitude of 3071 metres near the Teling village in the Lahaul valley. The tunnel’s south portal is located at an altitude of 3060 metres at a distance of 25 km from Manali.  Under the Prime Ministership of Atal Behari Vajpayee, the decision to build a strategic tunnel was taken on June 3, 2000.  Border road organization was the main organization which led the construction project. The Seri Nalah Fault Zone of 587 metres length which was completed on October 15, 2017, was the toughest stretch for completion for the BRO. The foundation stone for the access road to the south portal was laid on May 6, 2002. The first blast in the construction took place in 2010 and the last blast took place in 2017. Drill and blast NATM (New Austria Tunnelling Method) technique was used in constructing this tunnel. In this tunnel, air quality monitoring system has been placed at an interval of every one kilometer. Apart from air quality monitoring system, the tunnel also has telephone connections at every 150 metres, fire hydrant mechanisms at every 60 metres, auto-incident detection system with CCTV mechanism at every 250 metres and evacuation lighting and exit coordination system across the length. The tunnel also has an emergency exit setup at every 500 metres and a turning cavern at every 2.2 km.