From top: Railway workers prepare to unload freight at Hotan station in Xinjiang. Workers conduct their daily patrol of green belts in Qiemo, Xinjiang.

With 65 percent of its length located within Taklimakan — the world's second-largest shifting-sand desert in the Xinjiang Uygur autonomous region — sand control became the greatest challenge to construction and maintenance of the Hotan-Ruoqiang railway, workers said.

"We had to come up with innovative solutions to overcome those difficulties and such experiences have become great assets for us to build railways in even harsher natural environments," said Pu Falin, manager of the Hotan-Ruoqiang Railway Company, which is responsible for construction of the railway.

Taklimakan is a shifting desert. It is estimated that low sand dunes can move up to 20 meters each year. Frequent sandstorms have also posed a serious threat to the railway since its construction started in December 2018.

"We decided to build green belts simultaneously with railway construction, which has proved successful in preventing sands reaching the railway since it was put into operation more than a year ago," Pu said, adding that train services have so far been running smoothly.

A total of 50 million square meters of straw grids have been laid and 13 million trees, including red willow and calligonum desert scrub, have been planted along the 825-kilometer line, according to China Railway.

Li Delun, a member of the team maintaining the green belts who is based at Qiemo station in Bayingolin Mongol autonomous prefecture, said the trees have survived and are growing well. "If we had planted them after the railway was built, they wouldn't have been strong enough to protect the railway track," he said.

Wooden sand barriers have also been built while taller trees planted along the outer areas of the green belt to reduce wind speeds. Shrubs have been planted along the inner areas of the railway line to address the sand problem, Li said.

He Baofeng, head of the railway maintenance team at Qiemo station, said the rail track will lose its elasticity if too much sand gets underneath it. "The problem can make the railway unsafe, so sand control measures are crucial for the Hotan-Ruoqiang railway."

In areas where there are bigger sand dunes and stronger winds, five bridges with a total length of 49.7 km have been built to allow the desert to move underneath and keep the elevated track safe.

Instead of making the bridge piers on site, they were prefabricated and later assembled. It was the first time that this technique was used to build railway bridges. A total of 434 such bridge piers were built, Pu said.

"Prefabricating the concrete piers saved the construction team the trouble of transporting water into the remote desert to mix concrete, and also reduced the impact of sandstorms on their construction," Pu said. "We have done many experiments to finalize the procedure, which has now been standardized and can be used in other rail projects."

More than a year on, the sand control measures have helped to ensure the safe operation of the railway and the safety of the passengers, Pu said. "More railways will be built in Xinjiang, and we are now busy preparing for our next project, which can be even tougher. But the Hotan-Ruoqiang railway has made us confident in taking on more challenging tasks."