Passengers sit on a bullet train for Xi'an, capital of northwest China's Shaanxi Province, at the Chongqingbei Railway Station in southwest China's Chongqing Municipality, Dec. 6, 2017. High-speed trains linking Xi'an and Chongqing, began operation on Wednesday, slashing the travel time between the two cities from 9.5 hours to just 5.5. The new route includes a new section of the high-speed rail line linking Xi'an with Chengdu, capital of southwest China's Sichuan Province, which also started operation on Wednesday. (Xinhua/Tang Yi)