(190614) -- BEIJING, June 14, 2019 (Xinhua) -- Constructors work on the track of the Beijing-Zhangjiakou High-Speed Railway in a tunnel in Beijing, capital of China, on June 12, 2019. With the last steel rail piece laid Wednesday in a tunnel underground the Tsinghua University in Beijing, the track of the whole length of the Beijing-Zhangjiakou High-Speed Railway has been built. The original railway linking the two cities, known as China's first independently designed and built railway, was put into operation in 1909. With a designed speed of 350 km per hour, the 174-kilometer-long new track will shorten the travel time between the national capital and the city in neighboring Hebei Province to one hour, facilitating the inter-city traffic, crucial for their co-host of the 2022 Beijing Winter Olympics. (Xinhua/Zhang Chenlin)