An Introduction To Tripod Methodology

The following gives a brief introduction to the Tripod methodology.
Tripod was developed after 1988 by Research Teams from the Universities of Leiden and Manchester, working with Shell. Patrick Hudson was the leader of the Tripod Project at Leiden (Netherlands). James Reason was a professor at the University of Manchester, England, who had researched human error for 30 years.

At the time the Tripod research began, safety management was typically concentrating on the area of active failure, that is, the unsafe act/barrier/accident model. The Tripod research established that accidents and the area of active failure around them are but the final chapter of a longer story and that the primary influences of accidents are external factors (pre-conditions), which in turn originate from blunt end failures of the business (latent failures). Pre-conditions are specific to the accident whereas latent failures lie dormant in the system and are associated with specific organisational processes. After observing operators in a number of Shell Operating Companies and studying their accident records, eleven (11) General Failure Types were chosen to represent those workplace and organisational factors most likely to contribute to unsafe acts, thus providing a means of understanding why management inadequacies are occurring.

The General Failure Types are:

Level G.F.T Brief Definition
Senior Management IG Incompatible Goals - Conflicting requirements between safety objectives and individual, group or organisational goals.
CO Communications - Information necessary (or some part of it) does not reach correct recipients in a clear, unambiguous and intelligible form.
OR Organisation - Deficiencies in the structure or way of doing business which allow safety responsibilities and accountabilities to be ill defined and warning signs to be overlooked.
Front Line Management DE Design - Poor design, plant and equipment fundamentally inadequate.
HW Hardware - Deficiencies in quality and availability of tools, plant and equipment.
PR Procedures - Deficiencies in quality, accuracy, relevance, availability and workability of procedures.
TR Training - Deficiencies in knowledge and skills due to deficiencies in the training process.
MM Maintenance Management - Inadequate management of maintenance (not execution of maintenance tasks).
HK Housekeeping - Poor housekeeping usually present in the workplace.
Task Level EC Error Enforcing Conditions - Conditions that lead to errors and violations.
DF Defenses - Inadequate or absent protection against consequence of failure once it has occurred.

When conducting analysis using Tripod, the first step is to identify the breached “defenses”. Tripod expands the area of “defenses” beyond the traditional “ barrier” approach to encompass the following elements:

  • Create awareness and understanding
  • Give guidance on how to operate safety
  • Provide alarms and warnings of danger
  • Restore system to a safe state
  • Interpose barriers between hazards and losses
  • Provide for escape and rescue should containment fail.

Much can be learned by categorising the type of human error involved, particularly as a means of overturning the “blame” and “accidents are the fault of those having them” paradigm.

Human error can be categorised into three (3) main groups:

  • Skill based slips and lapses (Errors) - occur at ‘automatic’ level, where we do it automatically without having to think about it. Unintended, inevitable, unavoidable and exacerbated by fatigue and stress.
  • Mistakes (Errors) - using a set of “rules” (if…. then) from our past experiences (Rule Based) or working from first principles (Knowledge Based) we go through a process of thinking about what we’re going to do.
  • Violations - Deliberate actions, where we corner cut or get into bad habits at automatic level (Routine Violations) or optimise for the thrill of it (Optimising Violation) or because we have to get the job done (Necessary Violation). They occur in groups, within a regulated social context.

As we “practice” necessary and optimising violations we build them into our “automatic” skills and violate without conscious effort. This type of human error is commonly prevalent in our work places.

For those wishing to know more about what has been introduced, James Reasons’ book “Managing the Risks of Organisational Accidents” (ISBN 1 84014 105 0) is recommended.