All turnstiles at Metro stations in Shanghai will be equipped with scanners for passengers to swipe their phones to board the trains by the end of this year, the operator said on Saturday.

The city's subway network handled a daily record high of 12.23 million passengers on March 9, according to the Shanghai Shentong Metro Group. About 25 percent of the passengers use Metro Daduhui app on their phone to scan their way into the station on weekdays and 20 percent on weekends, said Yu Guangyao, head of the group.

Yet some stations have only two turnstiles that support QR code scanning at each exit, which has slowed down the passenger flow.