Glossary of Data Variables for Fatal and accident causation ... - ERSO

Manual For SafetyNet accident causation system (SNACS)
The purpose of doing a SNACS analysis is to find a probable connection among
these factors; a connection that can explain the observed consequences or the
event phenotype. The whole analysis process can be illustrated as in Figure 2:
Common Performance Conditions
(context dependent)
Genotypes
(possible causes)
Man
Phenotypes
(Categorises
dysfunctional
behaviour)
”Sharp
end
failure”
Observable
consequenses
of dysfunctional
behaviour
Vehicle
”Actions
at the
sharp end”
environment
Figure 3: Analysis with SNACS
Splitting the analysis into phenotypes and genotypes makes it possible to keep
the first step of the analysis (the phenotype step) fairly neutral, without jumping
straight to the causation part. This makes it easier for different persons to use
the method in the same way.
Once the cases are analysed, the results can be aggregated in such a way that
patterns among the contributing factors can be detected. The possibility to
aggregate the analysis results is a function of how the SNACS method is
constructed. The reason for developing the method in this way is that even
though every accident in a sense is unique, from a theoretical point of view, it is
reasonable to assume that accident scenarios which include similar
components also will have similar characteristics in terms of causation, and a
systematic approach is needed to uncover these characteristics.
6.5.1 Common performance conditions
The Common Performance Conditions (CPC) are used to describe contextual
conditions at the time and place of the accident. Each of the parameters among
the CPC evaluates the state of a dimension that is always present in some way
or another when driving, and which influences the driver’s performance
possibilities.
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