These notes provide some information on a number of important
theories and concepts developed by researchers in safety science, which
may be of interest to students and practitioners in safety management.
It also provides some descriptions of important historical events that
have changed risk engineering practice.
Rasmussen and practical drift
Pioneering safety researcher Jens Rasmussen described a phenomenon which he called
drift to danger, the
“systemic migration of organizational behavior toward accident under the influence of pressure
toward cost-effectiveness in an aggressive, competing environment”. Rasmussen and practical drift
The Heinrich/Bird accident pyramid
“safety pyramid”, first put forward by H. Heinrich in the 1930s, is a
widely used but misleading model of accident causation.
The Heinrich/Bird accident
The history of insurance
against risk is an ancient concept. Some elements of history, starting
in Babylonian times.
history of insurance
An accident on a flight from Rio de Janiero to
Paris illustrates the phenomenon of deskilling due to automation.
Air France flight 447
An “unsinkable” ship sinks, highlighting
the risks of technological hubris.
Interesting safety posters
Safety posters have long been commissioned by occupational safety agencies worldwide. A selection
of posters with striking graphical design.
Collection of safety posters
Denial and “distancing through differencing” are common after an accident, because we don’t
like to think that something similar could happen to us (we’re more skillful, or more careful,
or use better equipment).
Defence in depth
An ancient concept that dates back to the design of military forts with multiple layers of protection, which had to be
successively breached by attackers.
Defence in depth
A frighteningly hazardous phenomenon that can occur when a vessel containing a pressurized
liquid fails, leading to very rapid vapourization of the liquid in the vessel with a large blast effect.
A catastrophic explosion and fire on a North Sea oil drilling platform kills 167 people and leads to significant changes to regulation of offshore activity.
A shared belief within a workgroup that people are able to speak up without being ridiculed or sanctioned.
Whistleblowers: raising the alarm on safety issues
Reporting things that may constitute a threat to people or the environment, such as the presence of a risk which is not properly managed.
Safety culture: a contentious and confused notion
Safety culture is a nebulous concept related to the links between organizational culture, prevention practices and safety performance.
Farmer’s diagram, or F-N curve
An F-N curve is a graphical representation of the level of societal risk generated by some
activity or project, as well as society’s degree of catastrophe aversion.