The Impact of EN 50716 on Rail Digitalization and Advanced Technologies

Software now drives nearly every critical function in modern rail systems, from signaling and control to predictive maintenance and passenger services.

With the global rail market expected to reach $781 billion by 2030, advanced digitalization of the industry is picking up speed. In Europe, for instance, where some of the world’s most advanced rail networks operate, the bloc is doubling down on maintaining safety and reliability amid rapid rail digitization efforts.

Hence, the European Committee for Electrotechnical Standardization (CENELEC) introduced the functional safety standard EN 50716:2023 titled “Railway applications — Requirements for software development” to replace the legacy standard EN 50128. This marks a major shift in how safety-critical rail software is developed and validated.

Published in November 2023, the new standard updates software safety requirements for railway applications and embraces iterative development, artificial intelligence (AI), and machine learning (ML).

Here’s how the new standard works, plus the role Parasoft’s automated testing platform plays in streamlining its compliance.

Understanding EN 50716 and Modern Rail Development

EN 50716 is a harmonized European standard for railway software development released by CENELEC. The new standard is aimed to replace the legacy EN 50128 (2011) and EN 50657 (2017) frameworks.

The EN 50716 standard specifies the process and technical requirements for developing software in programmable electronic systems within railway applications, including control, command, signaling, and onboard rolling stock systems. It also aligns with evolving technological advancements such as model-based systems engineering (MBSE), Agile methodologies, and AI-driven solutions.

While EN 50716 represents a significant leap in European standards, the core requirements of its predecessors (EN 50128 and EN 50657) are still largely retained. The Railway RAMS standards (EN 50126 and EN 50129) are also not alienated since they are both aligned with the new standard.

One notable improvement to this standard is the extension of the mandatory requirements for formal proof verification techniques to now include lower SIL levels (SIL 1‐2), something not obtainable with the previous standards. This expansion reinforces the importance of high-quality and well-verified software throughout the modern railway system.

Software Quality and Safety Requirements in EN 50716

Critical railway application systems require stringent rules to maintain quality and safety. EN 50716 has a set of rules that ensure the software is designed, implemented, and maintained systematically throughout the railway software development life cycle with little margin for error.

The standard outlines a V-model development life cycle involving the design, coding, testing, and deployment of resources. Each phase must be well-documented, traceable, and aligned with risk assessments.

For example, SIL levels are determined via risk assessment to assign testing rigor. Even non-safety-critical software (SIL 1) must meet baseline quality requirements. To achieve this SIL compliance, developers often use static and dynamic analysis solutions such as those offered by Parasoft to enforce coding standards like MISRA, AUTOSAR C++ 14, and so on. They can also automate unit testing, integration testing, and test coverage, for example, statement, branch, compound condition, data flow, and path.

EN 50716 also integrates documentation and verification into a broader quality management system (QMS). The standard does this by mandating strict role separation, competency tracking, and 47 documented artifacts.

Another thing to note is that EN 50716 accommodates Agile and iterative models by requiring phased validation. Automated testing, formal methods, and simulation tools such as Parasoft’s IDE-integrated solutions may be used to detect defects early.

The standard also requires audits, independent assessments, and change control procedures to ensure modifications do not introduce new risks.

Critical Role of Static Analysis in EN 50716 Compliance

It’s a commonly known truth that fixing bugs during the early stages of development is significantly cheaper than resolving them post-deployment.

Static analysis tools are good at detecting bugs, errors, vulnerabilities, or other issues like coding rule violations, memory leaks that might affect the security or functionality of software in railway systems.

EN 50716 standard underscores the important role of static analysis in ensuring compliance for rail software by enabling early defect detection through shift-left testing.

By integrating static analysis early in the development life cycle, rail developers can identify and resolve coding errors, security vulnerabilities, and deviations from safety standards such as MISRA, AUTOSAR C++14, and High Integrity C++ before they escalate into costly, systemic issues.

This proactive approach aligns with EN 50716’s emphasis on rigorous verification and validation across iterative or Agile workflows, which reduces rework and accelerates time to market.

Static analysis also quantifies code quality through metrics like complexity, readability, testability, and maintainability—all of which are key criteria recommended by the EN 50716 standard to ensure software reliability and safety. These metrics often guide developers and can streamline audits through the provision of traceable evidence of compliance.

Parasoft also helps developers satisfy this compliance rigor by addressing EN 50716’s demand for independently verified toolchains.

Beyond defect detection by way of static analysis, Parasoft’s code coverage analysis and unit testing frameworks can also ensure that teams meet safety, security, and reliability goals.

Comprehensive Testing Solutions for Rail Safety

In modern rail software development, developers often combine static analysis with dynamic testing methods to identify and resolve software defects as early as possible.

This dual approach is essential for meeting the rigorous safety, reliability, and efficiency requirements outlined in standards like EN 50716.

Static analysis is a method of examining source code without executing it. However, the EN 50716 standard also calls for dynamic analysis and that includes lots of test methods performed through code execution. Dynamic testing encompasses a wide range of methods, including:

• Unit testing. Verifying individual components or functions.
• Integration testing. Ensuring different modules work together correctly.
• System testing. Testing the entire application to ensure it meets requirements.
• Regression testing. Confirming that new changes don’t introduce new defects.
• On-target testing. Running tests directly on the hardware where the software will operate.

Traceability is another factor worthy of mention. This is crucial because it’s a mandatory compliance demand defined in EN 50716 for software at integrity levels 3 and 4. It builds stakeholder confidence by demonstrating thorough and focused testing aligned with all specified requirements.

Maintaining these requirement links manually is likely impossible, so automation plays a vital role in keeping traceability precise and up to date.

Solutions like those from Parasoft automate requirements traceability by linking test cases to requirement specifications in ALM tools like DOORS Next, Jama, Polarion, and Codebeamer, then creating bidirectional traceability matrices that verify every requirement is validated and all gaps are addressed.

Parasoft’s code coverage capabilities, including statement, branch, data flow, path, compound condition, MC/DC coverage, provide auditable metrics to meet all EN 50716’s SIL-dependent requirements.

EN 50716 also expands on development life cycle models, particularly in iterative life cycle models where developers repeat certain phases multiple times by breaking the project into smaller chunks. Instead of doing everything in a single, linear process, they do it in cycles. Each cycle, or iteration, refines the software requirements, designs, and tests.

Conclusion

Bridging the gap between legacy safety practices and the demands of a digitized future isn’t an easy task. EN 50716 provides a foundational framework to balance innovation with accountability as worldwide rail networks continue to integrate AI, IoT, and autonomous technologies.

Expanding verification requirements to lower SIL levels, mandating traceability across iterative workflows, and embracing modern methodologies like Agile and MBSE, the EN 50716 standard ensures that software quality and safety remain at the forefront of rail innovation.

For organizations navigating this transition, investing in certified toolchains and automated testing strategies will be key to unlocking the full potential of rail digitalization.