Staff members go through luggage for security check on a bullet train on the Lanzhou-Chongqing railway, Jan. 8, 2019. The bullet trains with a speed of 160-km-per-hour on Tuesday were put into service on the Lanzhou-Chongqing railway, which connects Lanzhou City in northwestern province of Gansu with the southwestern metropolis Chongqing. (Xinhua/Chen Bin)