Smart cards , used as transit passes , and integrated ticketing are used by many public transit operators . Card users may also make small purchases using the cards . Some operators offer points for usage , exchanged at retailers or for other benefits . Examples include Singapore 's CEPAS , Ontario 's Presto card , Hong Kong 's Octopus Card , London 's Oyster Card , Ireland 's Leap card , Brussels ' MoBIB , Québec 's OPUS card , San Francisco 's Clipper card , Auckland 's AT Hop , Brisbane 's go card , Perth 's SmartRider , Sydney 's Opal card and Victoria 's myki . However , these present a privacy risk because they allow the mass transit operator ( and the government ) to track an individual 's movement . In Finland , for example , the Data Protection Ombudsman prohibited the transport operator Helsinki Metropolitan Area Council ( YTV ) from collecting such information , despite YTV 's argument that the card owner has the right to a list of trips paid with the card . Earlier , such information was used in the investigation of the Myyrmanni bombing
Myyrmanni bombing
Myyrmanni bombing
Smart card