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PTX 2.0: An Open Standard for V2X in Public Transport

hamburg-busAt Herman, we have long believed that the future of public transport relies on open, interoperable, and easily integrable systems. That is why we are proud to be part of the project group that, together with Trapeze, Yunex, IVU, INIT and other partners, developed the PTX protocol — a new communication standard for integrating V2X technologies into public transport vehicles.

PTX introduces, for the first time, a unified and vendor-independent interface between C-ITS onboard units (V2X-OBU) and onboard computers (ITCS). For transport operators, this means greater flexibility, easier integration, and an end to technological dead ends.


Why PTX matters for public transport

Today’s buses and trams must communicate with urban traffic infrastructure — especially (but not only) for managing public transport priority at intersections. For effective priority control, the V2X-OBU needs data from the onboard computer. To make this work across different manufacturers, a shared standard is essential. Moreover, none of the existing protocols could transmit all necessary data (not even IBIS-IP or ITxPT) — until now, with PTX.

PTX defines messages between the OBU and ITCS using MQTT and provides open JSON schemas. The protocol enables key use cases relevant for public transport, corresponding to the C-ROADS terminology: PVD (traffic data collection), TLP (traffic light priority), and GLOSA (recommended speed for intersection approach based on the traffic signal plan).


Benefits for transport operators

PTX creates an environment that we consider the right direction for the entire sector:

  • Independence from individual vendors – no lock-in to a single closed solution with proprietary protocols.
  • Easier integration and lower costs – a unified interface reduces implementation and maintenance time.
  • Flexibility for upgrades – individual components can be modernized without replacing everything.
  • Innovation and healthy competition – openness attracts new companies and accelerates technological development.
  • Sustainability of solutions – the standard will continue to evolve, for example to support new use cases (driver warnings are planned for 2026).


How we contributed to the creation of PTX

We joined the project in 2023 as one of its founding technical partners. The first draft of the standard was created in spring 2023, and in the following years its development expanded to include additional major companies.

In June 2025, we participated in the public demonstration of the PTX protocol at the UITP Summit in Hamburg, attended by public transport experts from around the world. This was the first functional implementation of PTX, and its capabilities are demonstrated in the video available at the following link:


In autumn 2025, based on the experience from Hamburg, we worked with other experts to refine the specification into PTX 2.0, which has been available since December 2025 for use in projects and tenders. Given the very positive feedback from cities and operators so far, we are convinced that the protocol will become a standard part of procurement for OBU units.


Our view on open standards

“The PTX protocol specification represents a key step toward an open and interoperable V2X infrastructure. It allows us to focus on the quality of our OBU units without dealing with proprietary limitations of existing protocols and the permanently missing data they cannot provide. A standard developed by several mutually competing companies gives transport operators confidence that they are investing in a long-term sustainable solution.”
— Ivo Herman, Ph.D., Technical Lead C-ITS

For us, this project is proof that open standards are not just a theoretical principle, but a commitment we actively fulfill. We see the PTX Specification 2.0 as a clear step toward more transparent, interoperable, and long-term sustainable systems.


PTX is open to everyone

The specification is publicly available on GitHub, where developers can find all documents, JSON schemas, and governance rules. The community is open — we welcome comments and suggestions that will help further develop the standard.


Where to find the documentation

All materials — specifications, schemas, and supporting documents — are available on the English PTX GitHub page.
If you have any questions, feel free to contact us anytime — we are happy to help or connect you with the project group.


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