Bowties - good practice and guidance
Bowties are a type of risk analysis, giving a visual map of risk and are particularly useful at highlighting the effectiveness of risk controls.
The starting point for a bowtie is the top event, which is the point at which an organisation has lost control of the hazard. Causes lead to top event occurring, and consequences potentially result from the top event. When laid out in a diagram, these form the shape of a bowtie.
Risk controls are identified, to prevent the progression, either by preventing the top event from occurring, or by limiting the consequences. Escalation factors may weaken the controls.
Bowties are developed and agreed through workshops comprising relevant industry experts. The workshop participants agree the hazard and top event, and then the causes and consequences. They then discuss and agree the risk controls and the effectiveness of each, along each cause branch. The completed bowtie can be shared so that all concerned can see the risks and their control measures on a single page, can be published so that other industry partners can also use them, and can be used to develop guidance.
Bowties are applicable for cross-industry, sector or duty holder assessment of risks, safety decision making and prioritisation of risk improvement measures. They can be linked to procedures, activities and audit programmes, to incident investigation and to quantified risk analysis. They are easy for staff of all levels to understand and can be shared between industry partners. Risks relating to different duty holders can be shown on the same diagram, facilitating cooperation. They can be used for development of guidance or to drive safety monitoring.
RSSB, together with the rail industry has developed bowties for a number of risk areas including freight derailments, trespass risk and slip, trips and falls.