Workers build the New Badaling tunnel of the Beijing-Zhangjiakou high-speed rail line in Beijing on Dec 13, 2018. (Photo: Xinhua)

BEIJING - 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.