What is bow tie analysis?

Bow tie analysis takes its name from the shape of the resulting diagram: a central "knot" represents a specific top event (such as a chemical release), with potential causes branching out on the left and potential consequences branching out on the right — visually resembling a bow tie.

How a bow tie diagram is structured

  • Top event — the central hazardous event being analyzed (e.g., loss of containment)
  • Threats — the causes that could lead to the top event, on the left side
  • Consequences — the outcomes if the top event occurs, on the right side
  • Preventive controls — barriers on the threat side that stop the top event from happening
  • Mitigating controls — barriers on the consequence side that limit the impact if it does happen

Why bow tie analysis is useful

Unlike more technical hazard-analysis methods such as HAZOP or FMEA, bow tie diagrams are highly visual and easy to communicate to non-specialists — making them useful for training, incident investigation reviews, and demonstrating to regulators or auditors that specific controls are in place for a given hazard.

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