At 10:00 on July 3, with a resounding blast, the Qilian Mountain No. 2 Tunnel on the Mandera–Datong Highway (National Highway 569)—China's first "four-high" tunnel combining high cold, high altitude, high gas, and high hydrogen sulfide—successfully achieved breakthrough on its right tube, laying a solid foundation for full breakthrough and operation of the entire line.

The Qilian Mountain No. 2 Tunnel is located in the Ningchan River Valley of Xianmi Township, Menyuan County, Haibei Tibetan Autonomous Prefecture, Qinghai Province, at an altitude of over 3,500 meters. The left tube is 6,044 meters long and the right tube 5,963 meters. The surrounding rock geology inside the tunnel is extremely complex and highly unstable, making it prone to deformation, collapse, and mud and water inrushes after excavation. Coupled with the high gas and high hydrogen sulfide toxic and harmful gases in the coal-bearing strata, the tunnel has been listed by the Qinghai Provincial Department of Transport as Qinghai's "No. 1 high-risk project" and is currently the most difficult highway tunnel under construction in the province.

The project began construction in September 2015. To safely and smoothly bore through the Qilian Mountains, the project department raised the safety risk level, organized experts to conduct on-site surveys, adjusted the construction plan, and carried out explosion-proof modification and upgrading of all construction equipment. Prudent and meticulous risk response measures and reliable system safeguards built a safety protection wall for the "four-high" tunnel construction.

To carry out construction scientifically and efficiently, Qinghai Transportation Construction Management Co., Ltd. also organized the Mandera–Datong Highway Section 1 project department of China Railway 16th Bureau to establish an innovation studio, producing 13 authorized patents and 6 innovative construction methods. These safeguarded the tunnel's safe passage through the 580-meter shallow-buried accumulation body of gravelly soil, the 1,628-meter high-gas section, and the 400-meter coal and gas outburst section, filling multiple gaps in highway tunnel construction and accumulating rich experience for similar tunnel projects.

The builders of the Mandera–Datong project are known as the "vanguard company" working inside a "gas canister." In the damp, stuffy tunnel, workers must wear gas masks and carry self-rescuers weighing about 3 kilograms, while also enduring the test of high altitude. Dizziness, nausea, eye pain, and difficulty breathing are common, and every few minutes they must stop to gasp for air due to oxygen deficiency. Every day when they emerge from the tunnel, their faces are covered in thick coal dust and grease, so much so that even the facial recognition system cannot identify them.

From the arduous passage through more than 500 meters of soft, water-rich, asymmetrically loaded ground, to successfully tackling a single mud and water inrush of 8,000 cubic meters; from suffering the assault of toxic and harmful gases such as high gas and high hydrogen sulfide after entering the rock, to a coal and gas outburst that ejected 515 tons of coal and 25,000 cubic meters of gas... Over more than 3,000 days and nights of perseverance, the construction team always maintained strict requirements and high standards, never flinching in the face of heavy responsibilities, and finally achieved a major breakthrough.

"The smooth breakthrough of the right tube of the Qilian Mountain No. 2 Tunnel is only a phased breakthrough; the tasks ahead are more arduous and the construction more difficult. Next, I will lead the project team to go all out and organize scientifically to ensure the safe and smooth breakthrough of the left tube," said Wen Jiawei, head of the Mandera–Datong Highway project of the First Company of China Railway 16th Bureau.

It is understood that once the Mandera–Datong Highway (National Highway 569) is fully completed and opened to traffic, it will achieve a short-distance, rapid connection between the Beijing–Tibet Expressway and the Lianyungang–Khorgos Expressway trunk lines in the western region, and open up a fast and convenient corridor between Xining, the capital of Qinghai Province, and Wuwei City in Gansu Province, an intermediate node on the Lianyungang–Khorgos Expressway. The drive time will be shortened from eight hours to two and a half hours, which is of great significance for boosting economic development in the five provinces of Qinghai, Gansu, Inner Mongolia, Ningxia, and Shaanxi and promoting exchanges and cooperation between provinces and cities.