A track recording car runs on the Jinshan Yellow River Bridge on the Datong-Xi'an passenger railway line in Yuncheng, north China's Shanxi province, March 10, 2014. The Datong-Xi'an passenger railway line from Datong of Shanxi province to Xi'an, capital of northwest China's Shaanxi province, has a designed speed of 250 kilometers per hour and will shorten the travel time between the cities from 16 hours to three. The railway's segment from Xi'an to Yongji of northwest China's Shaanxi province is now under debugging. [Photo by Xue Jun/Xinhua]