The world's highest highway tunnel（公路隧道）, Mila Mountain Tunnel, was open to traffic on April 26, 2019, at an altitude（海拔）of over 4, 750 meters above sea level in Southwest China's Tibet.
The two-way tunnel is over 5. 7 km long, which is a part of the 400-km highway connecting Lhasa with Nyingchi. People started building the tunnel on the 5, 018-meter-high Mila Mountain in 2015. And it was finished in 2019, helping shorten the 18-km distance over the mountain to 5.7 km.
It wasn't easy to build the highest tunnel in China. Terribly cold weather and too little oxygen（氧气） were two main difficulties. Besides, carrying everything to the building site（工地） was a great challenge for over 2, 000 workers.
However, everyone at the site worked hard to finish building the tunnel on time and more than 10 latest techniques were developed while the workers were doing this great project. "We've worked here for several years and lived in simple houses," said Xu Yong, the leader of the project. "Everything was so difficult, but we never feel sorry for ourselves here. It is a great project. "
The highway is an important way to the eastern part of Tibet. It can help to make more people visit Tibet and bring traffic convenience to local people.
