Workers work at a construction site of Datong-Zhangjiakou high-speed railway in Huai'an County, north China's Hebei Province, June 8, 2018. The high-speed railway, connecting Datong City in north China's Shanxi Province and Zhangjiakou in north China's Hebei Province with designed speed at 250 kilometers per hour, is expected to put into use at the end of 2019. (Xinhua/Yang Shiyao)