Why is the world`s highest Atal Tunnel built at 10,000 feet special?

A record 6,400 vehicles passed through the Atal Tunnel, an all-weather road under the 13,058 feet high Rohtang Pass in Himachal Pradesh, on Sunday. A few days after the ban on tourist activities was lifted, there has been a huge increase in the number of tourists. At 9.02 km long, at an altitude of 10,000 feet, it is the longest tunnel in the world.