The main contributing factor in the majority of accidents and incidents in industry, is human error. Human performance is therefore a key factor regarding safety. 

Human reliability may defined as "the ability of a person to carry out an action he has learned, under given circumstances, and for a certain period of time" (Leplat 1985). 

The investigation of the causes of human error in order to improve human reliability requires the study of both the human factor and the working system in the light of their interaction.

Human Reliability Assessment

There are three primary reasons for conducting a Human Reliability Assessment:

  1. error identification,
  2. error quantification and
  3. error reduction.

From such analyses measures can be taken to reduce the likelihood of errors occurring within a system and therefore lead to an improvement in the overall levels of safety.

Ergonomia offers several methods for the assessment of human reliability that fit the needs and characteristics of the full spectrum of work systems, including:

  • Hazard identification techniques (Human HAZOP, Technique for Human Error Assessment, THEA, etc.)
  • Expert judgement techniques (Absolut Probability Judgment, APJ, etc.)
  • BowTie method in Human Reliability Assessment.