5 – Preventative barriers
Preventative barriers are the barriers on the left side of the bowties. These barriers make sure the threat does not lead to the top event.
6 – Recovery barriers
Recovery barriers are located on the right side of the top event and take their effect once control over the hazard is lost. The recovery barriers make sure we do not have an accident and recover as fast as possible to normal operations.
Please note that you do not have to do this step by step. Sometimes you get stuck when you are defining the consequences or the threats, and you come to the conclusion that you need to redefine the hazard and top event. This is normal in the process of creating bowties.
Sometimes you need a step 7 and 8. These are the Escalation Factors and Escalation Factor barriers. Escalation factors degrade the effectiveness of the barrier. For example, if we have a seatbelt in the car as a barrier, an escalation factor could be ‘refusing or forgetting to wear the seatbelt’. Of course, we want to prevent this and therefore we add escalation factor barriers. In the seatbelt example, this could be a seatbelt alarm.
Factors to consider when creating your bowtie risk analysis
According to the ISO31000 guideline, you should consider multiple factors during the risk analysis phase. In our next blog post about risk evaluation, we will go deeper into that.