RISK MANAGEMENT
THE BOW-TIE METHOD
AN ELEGANT SOLUTION?
In a previous issue, Risktec discussed the steps of an effective risk management process and highlighted the importance of risk assessment/ analysis within this process. A number of differing techniques are available for assessing or analysing risk (e.g. risk assessment matrices) and in this issue, Risktec focuses upon a powerful and increasingly popular risk assessment technique, the Bow-Tie method.
WHAT IS A BOW-TIE?
The Bow-Tie method, so called because it describes the management of risk in the shape of a bow-tie, is an extremely powerful way of clearly illustrating how risk is being managed within an operation, business etc. It helps ensure that risks are managed rather than just analysed, partly by going beyond the usual risk assessment ‘snapshot’ and highlighting the links between risk controls and management systems.
A bow-tie diagram provides a readily- understood visualisation of the relationships between the causes of business upsets (hazards which, if realised, could compromise business objectives e.g. impact on health, safety, the environment, operations etc.), the
escalation of such events, the controls preventing the event from occurring and the preparedness measures in place to limit the impact (see Figure 1). The power of a bow-tie diagram is that it provides an overview of multiple plausible scenarios in a single picture.
BUILDING THE BOW-TIE
A bow-tie diagram is built by asking a structured set of questions in a logical sequence (see Figure 2). The completed bow-tie illustrates the hazard, its causes and consequences, the controls to minimise the risk, and a list of the critical tasks undertaken to ensure ongoing integrity of these controls.
Bow-ties are best constructed via facilitated workshops involving people who are regularly confronted with the risks. This is proven to be the most effective way of identifying real controls and capturing current practice. Honesty is an essential ingredient during these sessions if any weaknesses in controls are going to be uncovered. To encourage honesty, the workshop needs to be run in an open and engaging fashion, and an independent facilitator can often help to create such an environment.
To provide a practical example of a completed bow-tie, we can again look at our multi-purpose “Tiger in Cage” analogy. In this example, wild animals (i.e. tigers) are the hazard, with the top event (i.e. when control of hazard is lost) being tiger escape from the cage. The threats, consequences, barriers and recovery preparedness measures for this scenario can be easily understood at a glance as illustrated in Figure 3.
Figure 1: The Bow-Tie
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