The highest tunnel in the world

There is a mountain in Ganzi Prefecture, western Sichuan Province, called Quer Mountain, which has the title of "the mountain eagle can't fly over the peak" in the area. This is because its main peak has an altitude of 6168 meters and is deeply covered with snow for eight months every year, so it is also commonly called "the first danger of Sichuan-Tibet". There is a narrow dirt road built 65 years ago on the hillside of the Queli Mountain, which is the northern road from Sichuan into Tibet. Because of the frequent snowfall weather here, the vehicles walking on this road, once a car breaks down, it may cause a days-long traffic jam. This place is called the most dangerous highway in China by the drivers. When the ice and snow is big, there is no way for trailers to go. But now a great project has been built here, it is the highest tunnel in the world - Quer Mountain Tunnel.

The construction of the Quarry Hill Tunnel began in 2012 and was officially opened to traffic in 2017. It cost 1.15 billion yuan and took five years to build, solving the world's most difficult road underground project. It also broke several world records, including the world's highest tunnel in terms of altitude because it was built on a 4,300-meter plateau, and the world's longest tunnel because it was 12 kilometers long. Before this tunnel was built, people had to go around the dangerous mountain road for more than two hours, but after the tunnel was opened, it only takes ten minutes to pass easily.

But behind these achievements is the hard work of the workers. It is important to know that construction on the plateau is not the same as on the plain, where the oxygen in the air is only 48%. Therefore, when workers work inside the cave, they have to inhale oxygen once an hour at most. At the same time, operating at an altitude of 4300 meters above sea level, the mobility of personnel is very high. The plain tunnel could be built by 200 people, but for this tunnel, thousands of people worked for it. The harsh construction environment put every engineering staff under great pressure.