Maintenance crews keep trains safe on Gansu's desert railway bridge

A railway track may look perfectly straight to the naked eye. But on a bridge spanning a shifting desert, even a tiny deviation can pose a safety risk, and spotting it is part of the daily work of railway maintenance crews in Northwest China.

At the Shashangou Railway Bridge in Gansu province, workers inspect track gauge, alignment, and level on a structure rising more than 30 meters above the desert floor. They are, in effect, "specialist doctors" for the railway, diagnosing and correcting problems before they affect train operations.

Stretching 10.6 kilometers across the Kumtag Desert, the bridge is the only major railway bridge in China to cross an active desert. Supported by 324 piers, it carries the Dunhuang-Golmud Railway through a landscape of shifting sands, frequent sandstorms, and extreme temperature fluctuations.

For Wang Shenghu, a 28-year-old maintenance team leader, the work begins with a demanding climb. He and his colleagues carry tools weighing more than 25 kilograms up 151 steps, then walk another one or two kilometers to reach the section requiring repairs.

"When I first climbed up here carrying dozens of kilograms of tools and looked out at the seemingly endless desert, the reality was a far cry from what I had imagined," Wang said.

The 15-member team responsible for the bridge and surrounding railway infrastructure includes 12 workers born in the 1990s or 2000s. Together, they maintain the bridge, 70 kilometers of track, 25 sets of turnouts, and three stations.

Their workplace tests both physical endurance and technical precision. Annual precipitation in the area is just 24 to 38 millimeters. Temperatures can reach 35 C in summer and fall to minus 30 C in winter. Rail temperatures can climb above 50 C under the summer sun, while frost quickly gathers on workers' eyelashes and hat brims in winter.

"These temperature changes cause the bridge structure and tracks to expand and contract. Combined with the repeated impact and bending caused by heavy freight trains, they can lead to frequent changes in track geometry," said Yang Jianping, head of the Dunhuang Railway liaison team at the Jiayuguan Works Section of China Railway Lanzhou Group.

"Even a track that looks perfectly straight may have subtle deviations that affect train safety, so we must inspect and adjust it regularly," Yang said.

The checks follow strict technical standards. The standard track gauge is 1,435 millimeters, and deviations exceeding 6 mm on the wider side or 2 mm on the narrower side are classified as defects. Deviations in track level, elevation, or alignment exceeding 4 mm require timely correction, said Zhang Wenjie, Party chief of the Aksay track maintenance workshop.

Workers must complete repairs within a two-hour maintenance window. They remove track ballast, realign displaced ballast-retaining plates at bridge joints, replenish the ballast, and use specialized equipment to level and tamp the track. Temperature changes and repeated train loads can shift the plates, allowing ballast to fall through and creating potential hazards.

"When I see a train pass smoothly over the bridge, I feel a sense of accomplishment," Wang said.

The bridge became operational in December 2019 as part of the Dunhuang-Golmud Railway, which links Gansu and Qinghai with the Xinjiang and Xizang autonomous regions. By connecting major railway corridors in Northwest China, the line has shortened rail transport distances between Xinjiang and Xizang by about 1,100 kilometers, saving nearly 10 hours.

Zhao Tong and Zhang Xiang contributed to the story.