A technician maintains a train at workshop at Chongqing passenger section of China Railway Chengdu Group Co., Ltd. in Chongqing, southwest China, Jan. 26, 2021. Chongqing passenger section of China Railway Chengdu Group Co., Ltd. carries out maintenance works for the key parts of trains to prepare for the country's annual Spring Festival travel rush. (Xinhua/Tang Yi)

A technician maintains a train at workshop at Chongqing passenger section of China Railway Chengdu Group Co., Ltd. in Chongqing, southwest China, Jan. 26, 2021. Chongqing passenger section of China Railway Chengdu Group Co., Ltd. carries out maintenance works for the key parts of trains to prepare for the country's annual Spring Festival travel rush. (Xinhua/Tang Yi)

Technicians maintain trains at workshop at Chongqing passenger section of China Railway Chengdu Group Co., Ltd. in Chongqing, southwest China, Jan. 26, 2021. Chongqing passenger section of China Railway Chengdu Group Co., Ltd. carries out maintenance works for the key parts of trains to prepare for the country's annual Spring Festival travel rush. (Xinhua/Tang Yi)

A technician maintains a train at workshop at Chongqing passenger section of China Railway Chengdu Group Co., Ltd. in Chongqing, southwest China, Jan. 26, 2021. Chongqing passenger section of China Railway Chengdu Group Co., Ltd. carries out maintenance works for the key parts of trains to prepare for the country's annual Spring Festival travel rush. (Xinhua/Tang Yi)

A technician maintains a train at workshop at Chongqing passenger section of China Railway Chengdu Group Co., Ltd. in Chongqing, southwest China, Jan. 26, 2021. Chongqing passenger section of China Railway Chengdu Group Co., Ltd. carries out maintenance works for the key parts of trains to prepare for the country's annual Spring Festival travel rush. (Xinhua/Tang Yi)

Technicians maintain trains at workshop at Chongqing passenger section of China Railway Chengdu Group Co., Ltd. in Chongqing, southwest China, Jan. 26, 2021. Chongqing passenger section of China Railway Chengdu Group Co., Ltd. carries out maintenance works for the key parts of trains to prepare for the country's annual Spring Festival travel rush. (Xinhua/Tang Yi)