China has announced the opening of the world's highest highway tunnel, located at an altitude of over 4,750 meters above sea level in southwest China's Tibet Autonomous Region, according to Chinese officials.

The two-lane tunnel, which is over 5.7 km long, is part of a 400-km highway, linking the regional capital of Lhasa with Nyingchi in the southeast of Tibet.

The construction of the tunnel started in 2015 on Mila Mountain and was completed last Monday, April 22, 2019.

The tunnel helps to shorten the 18-km distance over the mountain to 5.7 km.

Over 10 technological breakthroughs have been made during the tunnel's construction, such as improving the survey accuracy of mountain tunnels in extreme cold weather conditions and at high altitudes, Project manager of the Tunnel, Gong Bin, said.

More than 2,000 workers faced the challenges of transporting living and construction materials to the site, coldness, and lack of oxygen, ” Bin added.