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

Manual For SafetyNet accident causation system (SNACS)
6.2 Introduction
The analysis method SNACS (SafetyNet Accident Causation System) is a tool
for analysing traffic accidents and incidents through a systematic and balanced
description of the factors that can contribute to the development of an accident
or incident scenario. The goal of the SNACS analysis is to create an
understanding of accident scenarios which can function as a base for accident
preventative work.
SNACS is based on the existing method DREAM 3 . DREAM, in turn, is an
adaptation to the area of vehicle safety of a model called CREAM 4 . The
DREAM method has a Human-Technology-Organisation perspective, which
implies that accidents happen when the dynamic interaction between people,
technologies and organisations fails in one way or another, and that there is a
variety of interacting causes creating the accident. The latter part particularly
stresses one of the most important issues of the WP5.2 project; to be able to
survey the causes of the accidents.
6.3 The Accident model behind SNACS
An accident model is an abstract conceptual representation of the occurrence
and development of an accident. It describes how and why accidents happen, it
defines possible causes and interactions, and it directs data collection and
analysis, as well as the selection of countermeasures. On every occasion where
an accident analysis is carried out, a more or less explicit underlying accident
model can be identified. If the model is inadequate for describing the problems
of the domain, the accident analysis and countermeasure selection will be
inadequate too 5 .
Modern road traffic is a complex, rapidly changing and dynamic environment,
which makes it a good example of a so called socio-technical system. In this
system, the task of the driver is gradually becoming more and more
complicated, while at the same time the demands for a reduction in the number
of accidents are increasing. This leads to certain requirements that need to be
met by an accident model for modern road traffic:
• It needs to provide adequate concepts for describing the factors that can
lead to an accident within the domain. Because of the interdependencies
and the tight structural coupling between the elements of modern road
traffic, the model also needs to describe how the contributing factors
interact with each other.
3 Ljung, M., DREAM – Driving Reliability and Error Analysis Method, Linköping University, 2002
4 Hollnagel, E., CREAM - Cognitive Reliability and Error Analysis Method, Elsevier Science,
Oxford, 1998
5 Huang, Ljung, Hollnagel & Sandin, Accident models for modern road traffic – changing times
creates new demands, IEEE International Conference on Systems, Man & Cybernetics, Hague,
Netherlands, 2004
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