Introduction to the Independent Safety Assessment (ISA) for railway applications

The Independent Safety Assessment (ISA) is a process for evaluating the safety of railway applications, including their subsystems, throughout their entire life cycle. This training unit will cover the basic activities of an Independent Safety Assessor in different phases as described in the CENELEC Standards.

The ISA process is carried out by an Independent Safety Assessor (ISA), who is an individual or organization that is independent of the railway application developer and is responsible for assessing the safety of the application. The ISA evaluates the safety of the application based on its compliance with applicable safety standards, regulations, and best practices.

The ISA process involves several phases, which are defined in the CENELEC Standards. These phases include:

• Hazard identification: In this phase, the ISA identifies potential hazards associated with the railway application and its subsystems.
• Risk assessment: In this phase, the ISA assesses the level of risk associated with each identified hazard. The risk assessment includes the likelihood of occurrence and the severity of consequences.
• Risk reduction: In this phase, the ISA identifies and evaluates safety measures that can be implemented to reduce the level of risk associated with each identified hazard.
• Safety validation: In this phase, the ISA evaluates the safety measures that have been implemented to ensure that they are effective in reducing the level of risk associated with each identified hazard.
• Safety assessment: In this phase, the ISA provides an overall assessment of the safety of the railway application based on the results of the hazard identification, risk assessment, risk reduction, and safety validation phases.

The Independent Safety Assessment process is essential for ensuring the safety of railway applications. It helps to identify potential hazards and assess their associated risks, as well as to identify and evaluate safety measures that can be implemented to reduce those risks. By providing an overall assessment of the safety of the railway application, the ISA process helps to ensure that it meets the required safety standards, regulations, and best practices.