XINING, China -- September 01, 2026 -- The Qinghai-Xizang Railway, a 1,956-kilometer line linking Xining in Qinghai province to Lhasa in the Xizang autonomous region, has carried 104 million passenger trips and moved more than 824 million tonnes of cargo since opening. The Golmud-Lhasa section, which opened on July 1, 2006 at an average elevation of 4,440 meters, has now completed two decades of continuous operation. Science and Technology Daily detailed the engineering systems, developed with support from China State Railway Group Co., Ltd. and China Railway Group's Northwest Research Institute Co., Ltd., that keep trains running through permafrost and low-oxygen terrain.
Fifty-one Unattended Stations Run on Satellite-Linked Control System
The 1,142-km Golmud-Lhasa section operates 58 stations, of which 51 are remotely controlled and unattended, according to Zhang Huxiong, head of safety and quality inspection at the Golmud Electric Depot. The line originally relied on satellite-based positioning to move trains across uninhabited stretches without ground signals. China State Railway Group Co., Ltd. backed research to adapt the domestically built train monitoring system to plateau conditions, reinforcing the weather resistance of resistors and capacitors and stabilizing performance in low temperatures and low oxygen. The upgraded system has since lowered maintenance costs and can be serviced domestically, and it now runs on trains across the Golmud-Lhasa section.
Thermosiphons Have Cooled 550 Kilometers of Permafrost for Two Decades
Gray metal rods called thermosiphons line both sides of the track along the 550-km core permafrost section. The technology traces back to a permafrost observation station on Fenghuoshan Mountain, at 4,750 meters, established in 1961 and still in operation. "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 at China Railway Group's Northwest Research Institute Co., Ltd. Researchers there built China's first thermosiphons for civil engineering use in the late 1980s. The sealed iron pipes, filled with liquid ammonia, absorb heat during warm seasons and release it as temperatures drop, extracting heat from the permafrost without external power.
Rising Temperature Projections Push Engineers Toward Solar-Powered Cooling
The original subgrade design accounted for a temperature rise of about 1.5°C over 50 years, but current climate projections point to an increase of up to 2°C. Li's team responded by developing solar-powered thermosiphons that draw on the plateau's intense solar radiation and wide day-night temperature swings, delivering 1.5 times the cooling capacity of standard units. The upgraded thermosiphons have been installed across 117 permafrost sections along the railway, cutting settlement by more than 70 percent at those sites.
Subgrade Settlement Stays Below 20 Millimeters on 96 Percent of Permafrost Track
Monitoring data collected over the past 20 years show that 96 percent of subgrade settlement on permafrost sections has stayed within 20 millimeters, well under the 50-mm design limit. Permafrost railways elsewhere in the world typically run under speed restrictions, but the Qinghai-Xizang Railway operates at 100 km/h, the highest sustained speed recorded for a permafrost high-altitude train service.