Safetyrequirements

Safety requirements are the defined conditions, constraints, and actions intended to prevent harm and reduce risk to an acceptable level in the design, production, operation, and maintenance of a system, product, or process. They translate hazards identified through risk analysis into concrete obligations for hardware, software, personnel, procedures, and environments. Safety requirements form part of the system's safety case and guide decisions throughout the life cycle, from concept to retirement.

In practice, safety requirements are elicited from hazard analysis, risk assessments, standards, and stakeholder needs. They are typically categorized as functional safety requirements—what the system must do to prevent or mitigate hazards—and safety integrity requirements that specify acceptable failure probabilities, diagnostics, and safety-related performance measures. Effective management requires traceability from identified hazards to specific requirements, allocation to subsystems, and rigorous change control.

The development process includes safety analysis methods such as failure mode and effects analysis (FMEA), fault tree analysis (FTA), and hazard and operability study (HAZOP), followed by design, implementation, verification, and validation activities intended to demonstrate that safety requirements are met. Verification and validation produce evidence, ultimately supporting a safety case that argues the system remains acceptably safe under defined operating contexts.

Standards and regulations provide structured frameworks for safety requirements. Well-known examples include ISO 26262 for automotive functional safety, IEC 61508 for general functional safety, ISO 13849 for machinery safety, IEC 61511 for process safety, and ISO 14971 for risk management of medical devices. Ongoing risk management and post-market feedback are important for maintaining safety requirements over time.