Mobile wallets eye public transportation for growth

Mobile wallets backed by various payment technologies are scrambling to grab a slice of China's public transportation market, which could become a multi-billion dollar business by 2020.

From Saturday, passengers in Shanghai can board underground trains by tapping their smart phones, the latest instance of making mobile payment a default way of life.

Through an app called Metro, passengers can choose to link their accounts with all bank cards issued by China's card payment processor UnionPay, or Alipay, the popular third-party payment platform from Ant Financial Services Group, and have the fees deducted every time they take a ride.