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02. How does SMS differ from system safety?

The key difference between SMS and system safety is how safety is managed under each approach. FTA’s PTASP rule requires transit operators to manage their safety risks through the implementation of SMS. SMS is a top-down, data-driven management system which involves the continuous collection and analysis of information that helps a transit operator become proactive about how it addresses safety risks. In contrast, system safety—a common transit industry approach to safety—is an engineering discipline that incorporates safety into a system during its design and construction. 

System safety assumes that technical compliance with engineered solutions will result in safe operations. The safety plan requirements for rail transit agencies under FTA’s original State Safety Oversight Rule (49 C.F.R. Part 659) implemented system safety through 21 specific requirements for System Safety Program Plans (SSPPs). The major focus of system safety is to integrate risk management into the overall system engineering process rather than addressing hazards as day-to-day operational considerations.

While the system safety approach effectively resolves many hazards, new safety risks may emerge over time with deviations in work practices, performance changes in system equipment or component parts, degraded conditions, aging infrastructure, integration of old and new technologies, and workforce changes. Using methods prescribed in the typical SSPP, it is difficult to identify and assess these new safety risks. By using the principles of SMS, the PTASP promotes the collection and analysis of more information from the frontline, supervisors, automated systems, customers, audits of normal operations, and other activities to help the rail transit agency manage safety risks and regularly monitor the effectiveness of safety risk mitigation. SMS also brings accountability for safety to the top levels of the organization, so the PTASP final rule requires each transit operator to designate an accountable executive who is ultimately responsible for managing safety and allocating resources to improve safety. SMS requires each employee and function within an organization to assume responsibility for safety, not just the safety office. Two other key components of SMS are the safety risk management and safety assurance processes, where data is collected and analyzed, priorities are established, and solutions are introduced then measured against performance, and monitored and evaluated to ensure the solutions are effective.

A rail transit agency may use the safety process and procedures established under its SSPP as a baseline for SMS implementation under its new safety plan. Please refer to FTA’s PTASP website for a crosswalk document that provides guidance on how to transition an SSPP to a safety plan that meets the PTASP rule requirements.

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