Barrier & work safety analysis, Event trees, FMEA, Fault trees, HAZOP, Influence diagrams, Management oversight risk tree technique (MORT)
Focuses on the transfer of harmful energy to vulnerable objects (e.g., people), establithsing what barriers should have been in place to prevent the accident, or could be installed to increase safety. Energies are usually electircal, environmental condition, chemical, thermal, biological, radiation, or kinetic. Barriers may be on energy source, between source & target, on taarget itslef, or through separation of source and target in time and space.
In a barrier analysis you create a table with these columns:
Function of barrier, type of barrier (e.g., physical, administrative), Design features and assumptions, potential human errors. Physical barriers are more effective than administrative
Work safety analysis
WSA firstly needs a list of the work steps involved in the job (can be obtained by HTA). For each work (task) step, potential hazards are considered. It is presented in a table format that looks kind of like FMEA. Columns include, work step, hazard, causative factors, risk classification before and after (from 0-5), corrective actions
Originally developed for analysis of system reliability but can be used to study human reliability. This technique can be used to investigate the ways in which sequences of operator actions can develop and identify the possible end points and consequences of these sequences. Typically operator action is depicted as either a success or failure, in which case two paths would lead out of each node. ETs also provide the frameworks for probablistic analyses where probs of various actions r assessed.
What can event trees be combined with?
Fault trees. Whereas ETs work forwards to identify the consequences of errors, FTs work backwards to identify the causes of errors. It can be useful to 'hang' FTs from the various nodes of an event tree.