Escalation Factors are a valuable aspect of Bowtie Risk Assessments. They allow you to dig deeper into your organization and really assess the weaknesses of your safety Barriers. However a lot of people struggle to apply Escalation Factors in a useful and meaningful way.
The Theory
Escalation Factors are “conditions that lead to increased risk by defeating or reducing the effectiveness of barriers”, also called Defeating Factor or Barrier Decay Mechanism. In other words, Escalation Factors create the holes in the Swiss Cheese Model of James Reason.
Historical use & misuse
When people apply Escalation Factors in Bowties they often take them too far. As a result, some Bowties contain large amounts of Escalation Factors. Sometimes exceeding more than ten per Barrier. When you picture an average Bowtie with ten Threats on the left, five Consequences on the right and per line (scenario) three or four Barriers, you already have hundreds of Escalation Factors. The end result is an enormous Bowtie that is unreadable and has lost the real power of a Bowtie; visualization and communication of the risk.
Causes for misuse
Bowties can have too many escalation factors because of two main reasons:
Being too specific leads to an exhaustive list of very small factors that might have an impact. This is probably more common if you're used to building fault trees because those go into much more detail than Bowties. If the objective is to include all those factors and create a really detailed assessment this is not a problem. But if you want to manage your risks and use Bowtie as a risk assessment to realize this, it is probably not the best approach
Being too generic: including things like “poor maintenance", “human error” or even “poor safety culture” will not get you anywhere. These factors apply to a lot of barriers and will result in the same escalation factors appearing over and over. Also, generic escalation factors cause you to think of equally generic Barriers to control them, like Competence management, Maintenance management, Auditing, Supervision, etc. These should also be avoided as they’re not describing specific Barriers, but instead whole management systems that support a whole range of Barriers.
Best practice approach
Based on our experience we’ve found that escalation factors work best when they’re used to identify and highlight a limited number of real problems or weaknesses in the organization. This approach leads to Bowties which do not exhaustively describe all the potential ways in which barriers can fail, but instead highlight key areas that need extra attention. Sometimes less is more, and this is certainly true for escalation factors. Use escalation factors as exclamation marks instead of exhaustive lists, and the communicative value of the Bowtie will be increased tremendously.