Passengers who made reservations scan their QR codes to enter Shahe station on the Changping Line in Beijing, March 6, 2020.[Photo by Wei Xiaohao/chinadaily.com.cn]

A passenger shows the QR code generated on the phone after successfully making a reservation, which allows the passenger to enter Shahe station via a fast track. [Photo by Zou Hong/chinadaily.com.cn]

Passengers who made reservations scan their QR codes to enter Shahe station on the Changping Line in Beijing, March 6, 2020. [Photo by Zou Hong/chinadaily.com.cn]