Builders of China Railway 14th Bureau Group work on the construction site of the Qinghuayuan tunnel on the Beijing-Zhangjiakou high-speed railway line in Zhangjiakou, north China's Hebei Province, May 6, 2019. At present, the Qinghuayuan tunnel on the Beijing-Zhangjiakou high-speed railway line is ready for laying tracks. The 174-km-long railway, connecting China's capital Beijing and Zhangjiakou of north China's Hebei Province, is a major transportation project for the 2022 Winter Olympic Games. (Xinhua/Xing Guangli)