Account-Based Ticketing (ABT) and ID-Based Ticketing (IDBT) are changing the way tickets are issued and stored. The ticket is no longer stored locally on a chip card or in a mobile phone, but in a back-end system. It is linked to an account, an identity or a payment method. When paying by bank card, a so-called token is generated, which links the payment method to the travel authorisation without disclosing sensitive card details.

New sales models require new infrastructure

This works well as long as all parties involved use the same system. However, as soon as transport network boundaries come into play or different transport operators work with different providers, a gap arises: ticket validation devices cannot find a valid authorisation locally because the ticket is stored in a different back-end system. As a result, ticket inspection teams outside a city or transport network boundary cannot validate tickets purchased, for example, by credit card. The ticket would therefore only be valid to a very limited extent – and thus not interoperable.  

The interoperable ticket store closes precisely this gap. It acts as a central hub that aggregates tokenised ticket data from various sales systems and transit payment environments. And this is independent of the data format used: if a ticket inspection device cannot find a valid authorisation locally during a check, it sends a request for the medium presented (such as a credit card) and receives the corresponding ticket in return. System boundaries no longer play a role in this process.

Data
protection thanks to pseudonymised tokens

Technically, the integration is based on a standardised interface compliant with OpenAPI 3.0, which the HUSST consortium developed on behalf of the NRW Centre of Excellence for Digitalisation (KCD). For each bank card, a unique token is generated in the ticket store, which identifies the authorisation without revealing any personal data. The calculation follows two mandatory procedures: the international ISO 24851 standard and our security procedure for (((eTicket Deutschland.

For passengers, this means that a ticket purchased by credit card in Bonn can also be validated in Düsseldorf or Krefeld. The project is funded by the Ministry for the Environment, Nature Conservation and Transport of the State of North Rhine-Westphalia. The interoperable ticket store for North Rhine-Westphalia is due to be operational by the end of 2026. In the long term, it will also be available throughout Germany. 

Transport operators benefit from standardised ticketing processes, the elimination of proprietary solutions, reduced technical complexity and greater reliability. At the same time, this creates a consistent, state-wide foundation on which existing and future digital projects in public transport can be developed in a harmonised manner.
Another practical advantage is that inspection devices do not require their own PCI certification, as they do not handle sensitive payment data directly but work exclusively with token requests.

Transport operators retain the freedom to choose their own systems and providers. Interoperability is achieved not through platform dependency, but through common standards. Validation checks across regional and system boundaries do not incur any additional transaction costs per transaction, and operations remain in the hands of the sector itself.
Looking ahead, we will expand the ticket storage system to include a background fare validation function. Validation devices will then receive not only ticket data but also a validation result directly. The complexity is shifted to the background systems, and ticket checks on board vehicles or on the platform become simpler and faster.