Improvement Cymru Academy Toolkit Guide: Bowtie safety model (December 2023)

Summary

The Bowtie model is a complex non-linear safety model and visualisation tool that can be used to describe an incident in relation to its initial causes, negative consequences and barriers that can be put into place to prevent or control the named hazard. It is called a Bowtie because when completed the diagram resembles the shape of a bowtie.

Content

The bowtie shape creates a clear differentiation between the proactive and reactive risks. The diagram has key areas that need to be identified:

1. Hazard: The activity, process or state that has the potential to cause harm.
2. Top event: The point chosen in time when control over the hazard is lost.
3. Threats: These are the possible causes for the top event.
4. Consequences: These are defined as the unwanted event caused by the top event.
5. Barriers: These are defined as measures taken to prevent, control or mitigate events
6. Escalation factors: These are defined as a condition that defeats or reduces the effectiveness of a barrier.

There can be one or more threats, consequences, barriers, and escalation factors.