India has completed the construction of the all-weather Atal Rohtang Tunnel, which will connect Manali to Lahaul and Spiti valley in the state of Himachal Pradesh (HP).

The Atal Rohtang Tunnel, which will be the world’s longest road tunnel at an altitude of 3,000m above sea level, is ready for vehicular movements and is scheduled to be inaugurated later this month.

Last year, the Union Cabinet renamed the tunnel Atal Tunnel, previously known as Rohtang Tunnel, after the former Prime Minister Atal Bihari Vajpayee.

Once in service, the 8.8km tunnel constructed in the Pir Panjal ranges of HP will connect remote border areas of the state and Ladakh throughout all seasons.

Due to snow, the Manali-Sarchu-Leh road is inaccessible for around six months a year, between November and April.

Atal Rohtang Tunnel will also reduce the road length of the Manali-Rohtang Pass-Sarchu-Leh road by 46km, reducing travel time by 4.5 hours.

The 10.5m-wide single-tube bi-lane tunnel includes a fireproof emergency escape tunnel built into the main tunnel.

In 2002, Vajpayee laid the foundation of the approach road to the tunnel.

Delays in construction escalated the project’s cost from Rs14.5bn ($20m) to Rs25bn ($34m).

In 2009, a contract was awarded to the Strabag-Afcons Joint Venture (SAJV) for the tunnel’s construction.

Afcons Hydro and Underground division director Satish Paretkar was quoted by Hindustan Times as saying: “We have faced multiple avalanches. In 2013, the tunnel collapsed at the north portal. In 2014, we had to evacuate the site in a hurry due to sudden harsh weather conditions… Army helicopters have had to be used to rescue nearly 100-150 workers.”

The tunnel has been constructed to provide access for the country’s forces to the prime military post, Lahaul. Once open, it will also become a key road for resupplying the military garrison to this place.