One of the most serious difficulties in building a Tibetan highway tunnel was working in an oxygen-poor environment.
The world's tallest highway, 4750 meters, was delivered to traffic on Friday in China, the autonomous province of Tibet.
The 5.7-kilometer tunnel under the 5018-meter-high Mila Mountain, a key section of a 400-kilometer motorway, shortens the route between Tibetan capital Lhasa and Nyingcsi in the south-east of the province.
During construction, at least 10 "technological breakthroughs" were achieved in working in extreme cold and high altitude (in an oxygen-poor environment), including engineering work, "the contractor said.
The motorway shortens the route between eight and three to four hours between Lhasa and Nyingcsi.
(Source: hvg.hu / photo: pixabay.com)