Cloud4Rail: How Virtualisation is Transforming Signalling and Control Technology
In European railway operations, operational orders – particularly those exchanged between signallers and train drivers – are a key safety instrument, especially in situations where signalling systems are insufficient or disrupted. Over the decades, however, numerous national procedures have evolved, making cross-border rail operations highly complex and resource-intensive.
Today, digital railway systems still rely on proprietary specialist hardware and tightly coupled hardware and software architectures. This makes modernisation and maintenance more difficult: hardware has to be supported over decades, modifications are complex, and the large number of different systems increases operational and maintenance costs. Cloud4Rail therefore pursues a new approach: signalling and control technology (SCT) is being virtualised. In future, applications from different suppliers will be able to run on commercial off-the-shelf hardware – similar to modern cloud and data-centre architectures in IT. At the core of this concept is the separation of the actual application (e.g. the interlocking central processing unit) from the hardware through standardised interfaces. This creates a more modular and flexible platform architecture for the digital railway system.
The project builds on the work of the Europe’s Rail Joint Undertaking programme and is testing the new architecture for the first time in technology pilots. In the long term, this is expected to:
- reduce investment and operating costs,
- simplify the integration of centralised services,
- improve the scalability and maintainability of systems,
- reduce supplier dependencies,
- and enable resilient and modern operational control structures.
At the same time, virtualisation consistently advances the future-oriented evolution of historical safety architectures. Functions that have so far been implemented on supplier-specific and physically separated systems can in future operate on shared IT platforms and make efficient use of the available resources of modern industrial servers – without reducing functional safety.
A video (in German) clearly explains the Cloud4Rail approach and demonstrates how the standardised decoupling of railway applications and IT platforms enables signalling and control applications from different suppliers to operate on a consolidated platform.
A recent technical article in SIGNAL+DRAHT (04/2026) explains how safety-critical signalling and control functions up to Safety Integrity Level 4 (SIL 4) can be operated in virtualised environments and which challenges need to be addressed.
The article compares two fundamental architectural approaches:
- safety-certified virtualisation with guaranteed isolation, and
- open, non-certified virtualisation with additional safety mechanisms.
The article demonstrates why the virtualisation of system-critical functions is technologically demanding and highlights the opportunities it offers for a future-proof, more flexible and more efficient railway system.
