Google Wallet for Transit has two different solutions that are termed closed loop:
- The emulation of closed loop cards
- The ability to save and convey a token that represents a backend account
In both cases, these transit cards can only be used within the transit agency's network.
Emulation of closed loop cards
Google Wallet for Transit enables the emulation of closed loop cards for public transit agencies with popular protocols such as MIFARE DESFire and MIFARE Plus, CMD2 (ITSO), and others. This solution acts the same way as a physical card, where the phone is the source of truth and the phone simply emulates the behavior of a typical closed loop plastic card.
This lets Public Transit Operators (PTOs) issue virtual cards with the same protocols used by their existing fare validators. This is most suitable for agencies with complex fare rules on the gate terminals who don't plan to enable an account-based system.
For more details, see Prerequisites.
Account-based cards with tokens on the phone
Google Wallet for Transit enables new account-based solutions, where the transit agency maintains a backend account for each user. In this case, the phone only holds an account identifier, and the source of truth is on the transit agency server. This is similar to a typical bank account model.
Google Wallet supports EMVCo-based transit tokens, described here as a Private Label Card (PLC), and acts as the account identifier. This solution uses the same technology as open loop payments for the conveyance to the terminal, but the PLC is usable only within the network of the transit agency.
Public Transit Operators (PTOs) who already support open loop payments can use the same EMVCo-based technology on their fare validators.
For more details, see Prerequisites.
Solution
Transit agencies that integrate with one of the preceding solutions can let users purchase and store a virtual transit card on their mobile device. These cards can have a prepaid balance, passes, or both. The cards show important information, such as available balance, and ticket details like expiry, validity of pass, recent transactions, or travel history.
Users can also top-up their balance or purchase additional tickets directly through Google Wallet or through a transit agency's own app. There is minimal visual UI difference between a closed loop card and an account-based card.