For many years, interoperability in the railway sector was understood as the ability to integrate systems from different manufacturers so they could communicate and operate together. The objective was to ensure compatibility between subsystems and guarantee that each fulfilled its role within the train's onboard architecture.

That remains an essential requirement, but the reality of the industry has evolved.

The digitalization of rolling stock, the integration of new onboard systems, and increasing connectivity are transforming the way fleets are designed, operated, and maintained. Today, onboard systems no longer remain unchanged throughout the train's service life. Instead, they continuously evolve through software updates, equipment replacement due to obsolescence, the addition of new functionalities, and adaptation to new operational, regulatory, and cybersecurity requirements.

In this context, interoperability is no longer simply about ensuring that systems work together on the day the train enters service. The real challenge is ensuring they can continue to integrate and evolve over the next thirty years while maintaining the levels of safety, availability, and reliability required for railway operations.

The real challenge begins after commissioning

Most of the rolling stock currently operating on European rail networks will remain in service for several decades. During that time, subsystems from different generations, technologies developed by different manufacturers, and solutions that must continuously adapt to new operational requirements will need to coexist.

It is precisely in this scenario that the real challenge emerges. Updating an onboard system, integrating a new subsystem, replacing obsolete equipment, or complying with new regulatory requirements can affect the balance of the entire onboard architecture if it has not been designed to evolve.

For this reason, interoperability can no longer be understood solely as the ability to exchange information between systems. It must also ensure that this integration can be maintained over time, preserving subsystem compatibility, data integrity and traceability, secure communications, and service availability.

This shift in perspective is driving transformation across the railway industry. Manufacturers, operators, and maintainers are increasingly adopting more modular architectures, improving lifecycle management, and enhancing their ability to integrate new technologies without compromising the stability of existing platforms. At the same time, capabilities such as remote monitoring, condition-based maintenance, secure software updates, and the use of operational data are becoming increasingly important for maximizing fleet availability and reducing maintenance costs.

Designing systems that are ready to evolve

Meeting this challenge requires a different approach to onboard systems integration. It is no longer sufficient to ensure that every subsystem operates correctly during development and commissioning. The platform must also be capable of incorporating new systems, new functionalities, and new requirements throughout its entire service life without compromising overall performance.

To achieve this, the railway industry is moving towards more modular architectures and comprehensive lifecycle management strategies that simplify the modernization of rolling stock. Configuration and version management, secure software updates, remote monitoring, condition-based maintenance, and the intelligent use of operational data all contribute to the same objective: minimizing the impact of technological evolution while ensuring fleet availability for decades.

After more than 25 years participating in railway onboard systems integration and implementation projects, we at Bilerro Solutions have learned that the real challenge is not integrating a system on the day it enters service. The real challenge is ensuring that integration remains valid years later, when operators need to introduce a new subsystem, update a critical application, replace obsolete equipment, or comply with new regulatory requirements.

That experience has shaped the way we work. We design and integrate onboard platforms that are built to evolve, enabling manufacturers, operators, and maintainers to incorporate new capabilities with minimal impact on existing systems. In an industry where rolling stock remains in service for decades, interoperability is no longer measured solely by the ability to connect systems, but by the ability to keep integrating them as technological, operational, and regulatory requirements continue to evolve.