Modeling Industrial Safety: A Sociotechnical Systems Perspective

[attachment=17846]
Abstract - Highly technological systems such as advanced
manufacturing systems, aviation, telecommunications,
nuclear power plants, chemical and petroleum process
industry are increasingly becoming more complex, leading to
new kinds of system failures and accidents. Traditional
safety modeling approaches are not suitable to analyze
accidents that occur in modern sociotechnical systems,
where accident causation is not the result of an individual
component failure or human error. This paper discusses
some traditional safety models and their limitations, and
describes new system-theoretic approaches to the modeling
and analysis of accidents in complex systems. This paper also
discusses emerging research in cognitive systems
engineering, sociological analysis, and resilience engineering
for safety analysis, accident modeling and safety
management of complex industrial systems.


I. INTRODUCTION
The main goals of system safety are to prevent the
occurrence of accidents in engineered systems and to
reduce their consequences if they occur. The IEC 61508
safety standard [1] defines safety as, “freedom from
unacceptable risk of physical injury or of damage to the
health of people, either directly or indirectly as a result of
damage to property or to the environment”.
Highly technological systems such as advanced
manufacturing systems, aviation, telecommunications,
nuclear power plants, chemical and petroleum process
industry are increasingly becoming more complex. Such
complex systems can exhibit potentially disastrous failure
modes [2], [3], [4], [5]. Traditional safety analysis
techniques are inadequate to handle the complexities of
such systems, and new promising approaches to the
modeling and analysis of safety and system accidents are
emerging.


II. TRADITIONAL SAFETY MODELS
A. Sequential Accident Models
Sequential accident models explain accident
causation as the result of a chain of discrete events that
occur in a particular temporal order. One of the earliest
sequential accident models is the Domino theory proposed
by Heinrich [6]. According to this theory there are five
factors in the accident sequence: 1) social environment
(those conditions which make us take or accept risks); 2)
fault of the person; 3) unsafe acts or conditions (poor
planning, unsafe equipment, hazardous environment); 4)
accident; 5) injury.


III. SOCIOTECHNICAL COMPLEXITIES IN
INDUSTRIAL SYSTEMS
In modern complex systems, humans interact with
technology and deliver outcomes as a result of their
collaboration; such outcomes cannot be attained by either
the humans or technology functioning in isolation. Such
systems, composed of human agents and technical
artifacts, are often embedded within complex social
structures such as the organizational goals, policies and
culture, economic, legal, political and environmental
elements. Sociotechnical theory implies that human
agents and social institutions are integral parts of the
technical systems, and that the attainment of
organizational objectives are not met by the optimization
of the technical system, but by the joint optimization of
the technical and social aspects [15].