RM Studio's Integrated Risk Management framework is expanding into the field of Engineering Hazard and Safety analysis. The new addition is a module designed for the methodology of Systems-Theoretic Process Analysis or STPA for short.
STPA(System-Theoretic Process Analysis) is a hazard analysis technique based on an extended model of accident causation. Component failures, unsafe interactions of non-failing system components, and social-technical systems or the combination of all three can be analyzed as a whole through STPA.
Advantages of STPA over traditional hazard/risk analysis techniques (from STPA handbook):
Very complex systems of both intended and unintended functionality
Can be started in concept and early design
Documentation of system functionality
Easily integrated into model-based system engineering
Supporting your integration of STPA into the systems engineering process.
Using STPA to provide leading indicators of risk, effective safety management system, and cyber security
The STPA module for RM Studio is a stand alone module that can be quickly installed and setup. The module includes a powerful modeling library provided by yWorks that is used in several elements of the module (CS modeling, Hazard - Loss relationship, Loss Scenarios). The STPA tool can be operated by one user or shared by multiple users in different locations to perform STPA.
Control Structure Modeling
Modeling the Control Structure (CS) is one of the first steps to building an STPA. The yWorks diagramming library is easy to use and extremely efficient for modeling the CS. Many hours were spent customizing the diagramming tool to perfectly fit with the requirements of the STPA Control Structure. Features included: drag-n-drop, annotation layer, one click control loop, and multiple diagrams for a single model.
Identifying Losses & Hazards
Another early step in the STPA process is the identification of Losses and the Hazards that lead to the loss. While creating your lists of losses and hazards, you can quickly link hazards-losses, hazards-hazards, and hazards-constraints. As a bonus, you can diagram the relationship between losses, hazards and constraints, providing you with an excellent animated visual representation of the connections between.
Unsafe Control Actions
Formerly know as Step 1, the Unsafe Control Action (UCA) identification is critical step in STPA. All of the Control Actions created in the CS diagramming are populated in the UCA analysis for you. After selecting the UCA categories (keywords) to use in the analysis, you are ready to assess. The hazards and constraints are available in the UCA analysis to link to the identified UCA.
The Loss Scenarios analysis (formerly Step 2) is the last step. The loss scenarios combine several components already created, such as the control loops from the CS, the UCAs identified, and the hazards. A Progress Check is used to ensure completion of and consistency in the Loss Scenarios, UCAs, and CS model.
We have put in a lot of effort over the years to learn and understand how to best apply STPA into any organization.
The research information contained in the case studies, research papers, and presentations is freely available for you to use to better understand how you can use our STPA solution.
Screen grabs of the tools above
You can get a simple view of the STPA solution from these, but we want to provide you with a proper demonstration on how it all works.
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