Assessment of human factor in critical infrastructures

Methodology for assessing human error probability under emergency conditions, taking into account internal and external factors, the degree of uncertainty, which can influence the reliability of a "man-machine" system, is presented. A model based on the HRA (Human reliability analysis) methodology is used. Probability of a human error is determined, which combines the nominal error and the influence of environmental conditions. The error is compared to the rated (design) permissible critical value dependent on the system state. It enables steadily monitoring the technical state of the system. In case of an unsatisfactory state, correcting actions are performed and probability for a human error is again assessed as well as the extent of the system improvement is tested. The methodology uses reliability criteria taking into account the degree of human involvement into the process of controlling critical infrastructures. The methodology includes efficiency analysis and assessment of the safeguarding system with regard to the human factor. Currently, there is no special documentation setting the procedure of human behavior under emergency conditions by means of quantitative methods. The methodology can serve the purpose of developing a practical manual for people having to make decisions; it can be used in training the personnel for acting in emergency situations. It is useful for assessing the influence of human factor on operation of critical infrastructures used for various purposes.