Bow-Tie Diagrams

An effective way to communicate risks and required responses is to use Bow-Tie diagrams.  Bow-Tie diagrams owe their name to their appearance:



At the heart of a Bow-Tie diagram is an undesirable event. To its left are the possible causes, to its right the possible consequences of the undesirable event.
In UReason software, Bow-Tie diagrams can be used for:



  • Root-cause analysis

  • What-If analysis

  • Containment purposes

When the heart-event of a Bow-Tie diagram is created,  this triggers the software to determine the likelihood of its connected root-causes. The heart-event may have been triggered by another event or alarm triggered by UReason rules, internal source, or by an external alarm or event.  On creation of the heart-event,  the barriers  to further unwanted events are monitored,  so that degradation of such barriers can immediately be reported to the controllers of the process.


A special mode of Bow-Tie diagrams lets your users to question what could happen if the undesired event is triggered. This allows you to train your controllers as to the causes and consequences of undesirable events.


An increasing number of government regulators for major hazard facilities (MHFs) - offshore oil & gas, aviation, etc - welcome safety-case submissions that use diagrammatic representation of risks at their core.  Bow-Tie diagrams are an ideal way to do this.  Using UReason software you can bring your Bow-Tie diagrams alive.