An engineer with China Railway Zhengzhou Group Co., Ltd operates a robot to scan and check a bullet train in Zhengzhou, central China's Henan Province, on Feb. 20, 2019. A growing number of robots are employed in China's railway system to improve efficiency and ensure safety, as railway trips are expected to hit 413 million in total during this year's Spring Festival travel rush, China's largest seasonal migration of people. (Xinhua/Li An)