XINING, China, Aug. 31, 2026 /PRNewswire/ -- A Report from Science and Technology Daily

The Qinghai-Xizang Railway, a 1,956-km steel artery traversing the world's highest plateau, has handled 104 million passenger trips and over 824 million tonnes of cargo since its inauguration. Twenty years ago, it ended the assertion that "the railway would never reach Lhasa." Today, a revisit to the route uncovers the technological safeguards behind this "Sky Road."

The line runs from Xining in Qinghai province in the east to Lhasa in Xizang autonomous region in the west. The section between Golmud and Lhasa, with an average elevation of 4,440 meters, opened on July 1, 2006. Since then, it has maintained safe and stable operations while expanding its transport capacity.

Digitally linking 51 unattended stations

The 1,142-km Golmud-Lhasa section has 58 stations, of which 51 are remotely controlled and unattended. The key to the railway's smooth operation over the past two decades lies in the train's control system, says Zhang Huxiong, head of safety and quality inspection at the Golmud Electric Depot of the Qinghai-Xizang Railway.

Originally, the system used satellite-based positioning for trains to operate without ground signals across uninhabited areas. "Wherever the train goes, you can see it from the sky," Zhang said.

To improve operational reliability and reduce maintenance costs, China State Railway Group Co., Ltd. supported research to adapt the domestically developed train monitoring system for plateau conditions. Modifications focused on enhancing the weather resistance of electrical components, such as resistors and capacitors, and improving system stability in low temperatures and low oxygen environments.

After years of intensive research and development, a plateau-adapted version of the system was successfully deployed.

It has proved itself with reduced maintenance costs and the ability to be serviced domestically. Today, trains equipped with the upgraded system run smoothly on the Golmud-Lhasa section.

Safeguarding 550 km of permafrost

Along the 550-km core permafrost section, gray metal rods known as thermosiphons line both sides of the track. This technology originated from a permafrost observation station on Fenghuoshan Mountain, at an elevation of 4,750 meters, built in the 1960s and still operational.

"The success of the Qinghai-Xizang Railway lies in the subgrade, and the success of the subgrade lies in the permafrost," said Li Yongqiang, chief engineer of the Northwest Research Institute Co., Ltd. of China Railway Group.

In 1961, China's first permafrost observation station was established on the northern slope of Fenghuoshan Mountain, where researchers have worked for generations despite extreme cold and low oxygen.

In the late 1980s, researchers developed China's first thermosiphons for civil engineering use. The sealed iron pipes, filled with liquid ammonia, absorb heat during warm seasons, vaporize and rise, then condense and flow back when temperatures drop, continuously extracting heat from the permafrost. During cold seasons, the process automatically stops, requiring no external energy. This wickless gravity-assisted heat pipe technology has safeguarded the railway for two decades.

However, climate change is presenting new challenges. The original design considered an increase of about 1.5°C over 50 years, but the latest projections suggest it could reach 2°C.

To address this, Li's team developed solar-powered thermosiphons, which use the plateau's intense solar radiation and significant day-night temperature differences to achieve cooling, delivering 1.5 times the capacity of ordinary thermosiphons. These have been applied to 117 permafrost sections along the Qinghai-Xizang Railway, reducing settlement by more than 70 percent.

Monitoring data show that over the past 20 years, 96 percent of subgrade settlement on the permafrost sections has been kept within 20 millimeters, way below the 50-mm design limit. While permafrost railways worldwide often face speed restrictions, the Qinghai-Xizang Railway operates steadily at 100 km/h, setting a global benchmark as the highest speed for any permafrost high-altitude train service in the world.