A woman displays the QR Code in a metro app on her smartphone. [Photo provided to chinadaily.com.cn]

Passengers in Shanghai can now use the city's dedicated metroapp to embark on metro trains in the neighboring cities of Hangzhou and Ningbo, a fresh step towards deepened integration of the Yangtze River Delta Region.

Beginning Saturday, metro riders can board trains in the three cities using a shared Quick Response Code embedded in their respective metro apps, Shanghai Shentong Metro Group, the local metro operator, said in a press conference.

The boarding process, which takes on average 0.3 seconds, circumvents the hassle of buying physical tickets or swapping mobile apps for entrance among the affluent YRD area, which includes Shanghai and neighboring Jiangsu, Zhejiang and Anhui provinces.

The attempt paves the way for comprehensive coverage of such services across the region's major cities by 2020, said Jin Tao,head of the information center at Shentong.

Wuxi in Jiangsu province is set to become the next city joining by the end of this year, according to Ye Tong, vice-president of Shentong. Also in the pipeline next year are Hefei, capital city of Anhui province, Suzhou and Nanjing in Jiangsu province and Zhejiang province's Wenzhou.

Mobile payment expert Alipay provides technological support to enable the interchangeability among different apps.

To roll out the service, the firm ironed out glitches, including system compatibility, cross-region clearance and payment stability in a poor internet connection, said Liu Xiaojie, general manager of city services at Alipay.

The combined subway route lengths of Shanghai, Hangzhou and Ningbo reached 862.1 kilometers, with daily passenger flow totaling 14.57 million on workdays, according to local transportation authorities.

The percentage of swiping phones to pay for metro fares in Shanghai, Ningbo and Hangzhou hit 23 percent, 25 percent and 50 percent, respectively.

Jin said local transportation authorities are working on the possibility of extending the shared QR code model to cover a wider range of transportation means, such as buses, ferries, taxis, shared bikes, or even inter-city high-speed railways.