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Helpful resources

This page provides access to additional resources to help practitioners understand and use Tripod Beta.


Tripod Beta: Guidance on using Tripod Beta in the investigation and analysis of incidents, accidents and business losses is the current manual on using the Tripod Beta methodology.

A link to Caused By Leads To document.Annex I: Caused by... Leads to... A method for identifying and classifying the underlying causes of incidents, accidents and business losses.   This resource is a companion to the Tripod Beta manual (Annex I).  It provides 11 tables of common preconditions and underlying causes.  These tables can guide the investigator on possible avenues of investigation, the level of depth expected of preconditions and underlying causes, and as a way to classify underlying causes consistently to enable multi-incident analysis.

Learning from incidents, accidents and events (ISBN: 9780852939277) - drawing upon the experience of 50 experts in investigation and learning from incidents, this is the definitive manual for learning from incidents.


Investigator 3 (external website)

  • Full incident investigation and analysis tool including Tripod Beta.  Ability to auto-create reports.

Incident XP (external website)

  • IncidentXP uses the same software framework as BowTieXP, which makes it possible to link incident analysis results back to the proactive risk assessment diagram. However, IncidentXP can also be used as full-fledged stand-alone incident analysis tool. Includes Tripod Beta.

Tripod Beta tree stencils: PowerPoint presentation (external website)

  • PowerPoint presentation containing blank Tripod Beta tree symbols, to enable you to create Tripod trees without using specialist software. To access, click the 'Tree stencils' tab towards the middle of the page.


Examples of Tripod Beta trees (and frequently made mistakes) in health care (hospitals)

In the medical sector, diagnosis of illness/harm to a patient is often seen as a barrier.  However, technically this is incorrect as a diagnosis in itself it not usually a valid barrier (it fulfills only one of the 'detect, decide, act' functionality of a barrier).  This paper demonstrates some correct ways to deal with issues of using Tripod in the medical sector.

Videos (now playable on both Widows and Apple Macs)

A collection of videos to help you understand the theory behind Tripod:

The Swiss cheese model explained - part 1

The Swiss cheese model explained  - part 2

Movie: Explaining Human behaviour

Movie: Human behaviour theory and Tripod BetaEnglish

Movie: Human behaviour theory and Tripod Beta French

Movie: Barge incident - a Tripod Beta case study

Background reading

UK P&I clubwebsite: Tripod theory (external website)

Contains excellent background to human failure and the Tripod theory. Note it uses older terminology (Hazard and Target rather than Agent and Object).

History of the Swiss cheese model (external website)

Shows how the Swiss cheese model has evolved over time.

Selection of incident investigation methods (external website)

October 2009 Loss Prevention Bulletin paper that describes a number of different incident investigation methodologies.  Note that Tripod Beta is the only method that covers 'what happened', 'how it happened' and 'why it happened'.

Case studies

Examples of Tripod Beta investigations:

Vehicle rollover in remote desert region (external website)

Chemical plant pipe rupture (external website)

Machine operator cuts hand (external website)

Passenger accident at Brentwood station 28 January 2011 (external website)