Environmental Engineering Reference
In-Depth Information
English potter Josiah Spode (1733-97) who became famous for perfecting the
transfer printing process and for developing fine bone china - but presumably
not without many failed attempts on the way. it provides an explanation or
brings about an understanding of an event such that effective mitigating
actions can be devised. Second, that it can be used with a reasonable
investment of effort - intellectual effort, as well as time and resources. A
model that is cumbersome and costly to use will, from an academic point of
view, from the very start be at a disadvantage, even if it provides a better
explanation. The trick is therefore to find a model that at the same time is so
simple that it can be used without engendering problems or requiring too much
specialized knowledge, yet powerful enough to go beneath the often deceptive
surface descriptions.
The most important models in the past have been the Domino model and
the Swiss cheese model [7]. Both are easy to comprehend and have been
immensely helpful in improving the understanding of accidents. Yet their
simplicity also means that some aspects cannot be easily described - or
described at all, and that explanations in terms of the models therefore may be
incomplete. In one, accidents are likened to a row of dominoes falling, and in
the other, to harmful influences passing through a series of holes aligned.)
In the case of the Domino model, it is clear that the real world has no
domino pieces waiting to fall systems or subsystems that suddenly may change
from a normal to an abnormal state, but that transition is rarely as simple as a
domino falling. Likewise, the linking or coupling between dominoes is never
assemble as the model shows. Similarly, the Swiss cheese model does not
suggest that we should look for slices of cheeses or holes, or measure the size
of holes or movements of slices of cheese. The Swiss cheese model rather
serves to emphasize the importance of latent conditions and illustrate how
these in combination with active failures may lead to accidents.
The Domino and Swiss cheese models are useful to explain the abrupt,
unexpected onset of accidents, but have problems in accounting for the gradual
loss of safety that may also lead to accidents. In order to overcome this
problem, a model of ‗drift to danger' has been used. Although the metaphor of
drift introduces an important dynamic aspect, it should not be taken literally or
as a model, for the following reasons:
Since the boundaries or margins only exist in a metaphorical sense or
perhaps as emergent descriptions [8], there is really no way in which an
organization can ‗sail close' to an area of danger, nor ways in which the
‗distance' can be measured. ‗Drift' then only refers to how a series individual
