On Saturday, Prime Minister Narendra Modi inaugurated the Atal Tunnel, which cuts the travel time from Manali to Leh by four to five hours. Throughout the year, the longest highway tunnel in the world by altitude would connect Manali to the Lahaul-Spiti valley. Due to heavy snowfall, the valley was previously cut off for around six months per year. Back in June 2000, the Atal Bihari Vajpayee-led government took the decision to construct the tunnel. It was formerly known as the Rohtang Tunnel.

In remembrance of the former Prime Minister, Atal Bihari Vajpayee, the Narendra Modi-led government later decided to name it the Atal Tunnel. The 9,02-kilometer-long tunnel is built at an altitude of 3,000 metres from the Mean Sea Level ( MSL) with ultra-modern specifications in the Pir Panjal range of the Himalayas.

The PMO said it is a horse shoe-shaped, single-tube double lane tunnel with an 8-meter roadway and an overhead clearance of 5,525 meters. It was planned for a traffic density of 3000 cars per day and a top speed of 80 km / hr for 1500 trucks per day.

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

It has a state-of-the-art electromechanical system including semi-transverse ventilation, firefighting operated by SCADA, lighting and surveillance system. From the point of view of the country's security, the tunnel, constructed at a cost of about 3,300 crore, is extremely important, the officials said. The 587-metre Seri Nalah Fault Zone was the most challenging stretch. On October 15, 2017, the breakthrough from both ends was accomplished.

Border Roads Organization (BRO) has done the major part of the construction. BRO had to overcome a number of weather, terrain and geological challenges to build the tunnel. Speaking of the tunnel, a BRO official said that it includes a telecommunications service every 150 metres, a fire hydrant every 60 metres, emergency exits every 500 metres, a cavern every 2.2 kilometres, air quality sensors every 1 km, a broadcasting system and an integrated CCTV incident warning system every 250 metres.