Open loop payment pilot starts on metro and bus services in Porto, Portugal July 23, 2021 | Europe News Littlepay has commenced the pilot of the ‘Tap-to-Pay’ open loop payment system on Porto Metro’s airport line and on Sociedade de Transportes Colectivos do Porto’s (STCP’s) bus line 500. The solution h... This content is available to only subscribers. Username or E-mail Password Remember Me Forgot Password