Safety-Critical Embedded Systems for Railway

Critical Software

CRITICAL Software supports railway manufacturers in the development, testing and certification of embedded systems, according to CENELEC EN 50126/8/9 standards up to the highest safety integrity level, SIL4.

We have substantial experience working with track-side equipment and rolling-stock control systems, including working with CENELEC standards, as well as real expertise in state-of-the-art technologies such as European Rail Traffic Management System (ERTMS) and communications-based train control (CBTC).

CRITICAL Software also provides turnkey condition-based maintenance solutions that complement our embedded systems capabilities. These solutions supports original equipment manufacturers (OEMs) and operators by adding value to the end-user experience, while enabling more efficient train fleets through improved maintenance management processes.

Independent safety assessments of railway systems

CRITICAL Software performs independent safety assessments (ISA) of railway systems, including:

  • Reliability, availability, maintainability and safety (RAMS) analysis with tasks such as hazard analysis (HA), failure modes effects and criticality analysis (FMECA), fault tree analysis (FTA) and reliability predictions
  • Mean time between failure (MTBF), Mean time to repair (MTTR) and mean down time (MDT) calculations
  • Preparation of safety cases
  • Full support and certification of rolling-stock control systems and track-side signalling systems

Testing, verification and validation projects for railway applications

CRITICAL Software also supports its clients in the development of safety-critical embedded systems by assuming responsibility for the complete verification and validation of systems or components.

We perform:

  • Complete verification and validation projects
  • Validation projects, including test specification, execution and reporting, ensuring compliance with the objectives of the CENELEC standards

Some of the techniques used include hardware-in-the-loop (HIL) testing on target environments, software-in-the-loop testing, nominal and robustness / stress testing, as well as validation through formal methods.

We are also capable of building customised system validation facilities for complete test automation, resulting in a significant reduction of effort required for regression testing.

Embedded software development

CRITICAL Software's embedded software development experience includes production of requirements, architecture, design and coding, as well as verification and validation activities as a whole.

We are able to work on all stages of the V-model, according with the independence principle. We are able to produce safety-critical applications (also using model-based methodologies), board support packages or real-time operating system (RTOS) components compliant with EN 50128, up to the highest criticality level.

In the particular field of refurbishment and evolution of legacy systems, we also have experience in gap analysis, reverse engineering, re-engineering and re-design of obsolete systems.

Condition-based maintenance

Improving the reliability, availability and efficiency of critical assets is crucial for the railway industry in order to increase safety and operational performance, while reducing running costs. Real-time data analysis avoids costly guesswork, ensuring that critical rail assets are as failsafe as possible.

By tracking assets' true condition and relating this information to business and operations records, maintenance schedules and usage forecasts, railway operators are able to maximise the usage of their fleet. With all of the available train information, condition-based maintenance processes can be used to reduce maintenance costs.

CRITICAL Software combines its data engineering, condition algorithms and key system integration capabilities to enable holistic monitoring of entire train fleets. Operators can monitor the status of different subsystems, assess their condition, predict failures and produce optimal maintenance plans.

Our knowledge and experience of the safety principles behind critical embedded systems spans across the railway and aerospace industries, allowing us to transfer cutting-edge technologies, knowledge and best practices from one field to another.

Contact Details

Parque Industrial de Taveiro, lote 49
+351 239 989 100
+351 239 989 119

Available White Papers


ERTMS and CBTC Side By Side: A Comparison of State-of-the-art Rail Traffic Management Systems 04 September 2017 There is a well-defined separation between the systems that are being used in Mass Transit networks and the ones being used for Mainline. However, each of these systems has the necessary maturity to step forward to an integrated solution that comprises the best of both worlds: European Rail Traffic Management System (ERTMS) and Communications-Based Train Control (CBTC) system.


Train Refurbishment Talking Points: Better Communication, New Embedded Systems and Existing Equipment 03 March 2016 Learn about integrating new embedded systems with existing equipment in this new white paper from CRITICAL Software. As the need for improved public transport continues to grow, the refurbishment of older stock is becoming increasingly common. But it can be difficult to merge systems that use older stock with newer technologies while maintaining operations at the same time. Discover how to avoid lengthy delays and unnecessary costs when merging systems, while ensuring safety remains a key priority.


Improving Railway Safety 28 January 2016 In this free white paper from CRITICAL Software, you can learn about the role of human factors in RAMS analysis, according to the specifications outlined in the CENELEC standards.


Advanced Engineering for Railway Rolling Stock: Moving to a New Engineering Dimension 19 March 2015 The liberalisation of rail transportation in Europe, which started in the 1990s, has changed the railway market. The flow of goods is moving quickly over ever greater distances, while the logistics are becoming more complex.


Automatic Train Control: An Overview of Available Systems 09 December 2014 An automatic train control (ATC) system integrates all the vital and non-vital functions that guarantee the safe operation of trains.