From EN 50128 to EN 50716: A New Software CENELEC Standard in Railway Software Development

The railway industry is evolving with the introduction of EN 50716:2023, the latest standard for software development in railway applications. Replacing EN 50128:2011 and EN 50657:2017, this new standard brings several crucial updates designed to enhance the development process for software used in railway systems.

Implementation Timeline and Major Updates

The withdrawal date for EN 50128:2011 is set for October 30, 2026, with an additional six-month period provided by CENELEC, extending the final deadline to April 30, 2027.

This timeline allows organizations ample time to transition to the new standard while continuing ongoing projects under the existing guidelines.

Key Enhancements in EN 50716:2023

1. Stricter Validator Competencies: The competencies required for validators have been made more stringent, ensuring a higher standard of software validation.
2. Clearer Role Definitions: The distinction between testing and verification roles has been clarified, reducing overlap and potential confusion.
3. Simplified Compliance Tables: Tables A-5 through A-8 have been simplified to facilitate easier compliance and understanding.
4. Flexible Development Models: The standard now allows the use of the V-model and other established software development tools, such as model-based testing, offering greater flexibility.
5. Streamlined Independence Requirements: The independence requirements for various roles have been simplified, improving workflow efficiency.

Rigorous Testing and Validation

One of the standout features of EN 50716 is its robust framework for software testing and validation.

The standard requires detailed Test Specifications and Test Reports, ensuring that software behavior and performance are thoroughly vetted against predefined criteria.

Additionally, the validation process is designed to demonstrate that the software meets all specified requirements and is fit for its intended application, providing an extra layer of assurance.

Better Alignment with Existing Standards

1. EN 50716:2023 aligns more closely with EN 50126-1:2017 and EN 50126-2:2017, ensuring consistency across related standards.
2. Clause 5 has been reworded for better readability,
3. Annex A has been updated to align with life cycle phases.

Formal Methods and Tool Diversity

The standard expands the endorsement of formal methods across all Safety Integrity Levels (SILs)

Addressing Modern Application Design

EN 50716 acknowledges the modern approach to application design, which often involves using configurable software as a basis for various applications. By providing guidelines for the development of User Programmable Integrated Circuits and the use of pre-existing software, the standard ensures flexibility while maintaining rigorous quality and safety standards.

Enhanced Flexibility and Adaptability:

EN 50716:2023 supports the iterative lifecycle approach, which enhances flexibility and adaptability in software development for railway applications. By allowing the use of the V-model and other established development tools, the standard enables continuous feedback and improvement through multiple iterations. This ensures that the software can evolve and adapt to changing requirements and feedback, ultimately leading to a more robust and reliable product.

Additional Recommendations

The standard introduces new clauses in Annex C, offering additional recommendations for life cycle models and software development modeling.

Conclusion

The introduction of EN 50716:2023 signifies a significant advancement in railway software development. By understanding and embracing these changes, organizations can ensure higher standards of safety, efficiency, and clarity. As we transition to this new standard, staying informed and proactive will be crucial for achieving compliance and excellence in railway software development.