Advanced Interstation Communication


For over 15 years PSA has provided permanent support and adjustments for the client’s wayside control products, helping meet location peculiarities, connectivity requirements, and digital advancements. In order to be utilized on modernized rail lines, the wayside controller required upgrades so that interstation communication could be provided in a fast, reliable, and fail-safe way. Otherwise, they couldn’t guarantee the correct transfer of data about wayside devices' status and train presence between stations’ controllers, which might disrupt signaling operations.


Client Challenge

Maintain top-tier reliability of interstation communication for the advanced signaling systems.

Project Objective

Expand the functionality of wayside controllers to maintain more complex messaging between each other in the field.


For the wayside controllers to transmit and receive more data at one time, it was required to modify the critical communication protocol. This advanced protocol ensures efficient and secure message exchange between wayside controllers, which has to be maintained after updates.

The PSA team provided protocol modifications for all the components involved in the interstation data transfer, namely:

  • Wayside controller’s firmware

  • Web component acting as a reliable gateway

  • Compiler, reverse compiler, and comparison tools for building and adjusting logic applications for the controller

  • Launcher for the tools’ installation

Working with legacy equipment, our team applied an out-of-the-box approach to flash the device, as well as investigated and eliminated an issue that didn’t allow for modernization. As a result, the controller started to support new message types and transfer messages differently.

The provided modernization guarantees reliable messaging for advanced signaling systems, while maintaining integrity, relevance, targeting, and timeliness of the message.

All the implemented changes have been validated using VectorCAST and are about to be implemented onsite.

To explore more technical details click here.

Development Included

  • Requirements definition
  • Software development
  • VectorCAST testing



  • Complex messages support

  • SIL4 enablement

Technology Breakdown

Project size
  • 4 Software Engineers
  • 15 months

Further Cooperation

The PSA team has deeply immersed itself in the client's safety-critical products to seamlessly implement upgrades any time when it’s required. In this way, we helped them to establish Wayside – CTC communication, increase availability for the wayside units, and create a simulator to validate interlocking logic for multiple scenarios. All the modernization activities support the mission-compliant operation of the controllers under CBTC, PTC, and ETCS requirements.

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