The Overall Independent Safety Assessor (O-ISA) is appointed to provide an independent, objective and expert evaluation of the safety-related activities undertaken throughout the entire lifecycle of the railway system from concept and design through to commissioning and revenue services. The O-ISA’s role is to ensure that the system is developed, integrated and operated in accordance with applicable safety standards, regulations and best practices, and that it achieves a demonstrable level of acceptable safety integrity for operations.






