th
TECHNICAL
these targets through proper design
and construction planning. However,
absolute confidence in engineering
design and construction planning is
403-569-6986 RSFoundations.ca
mind. A clear and universal definition
of risk is required so all team members
can communicate and assess
what is best for the project consistently.
For engineering purposes, risk
is not simply any unfavourable phenomenon
(threat) that could occur.
There are two angles on this definition
by the International Organization for
Standardization (ISO). First, the risk
is tied to the effect of the threat, not
only the presence of it. Risk is a factor
of hazards and consequences. Hazards
are defined as a probability of a threat
against an element of a project. The
consequence of the threat depends on
the vulnerability of the element at risk
and the value (or utility) of the element.
A simple formula would be:
Risk = Hazard × Consequences
Or
Risk = Hazard × Vulnerability × Value
Therefore, a threat which could
potentially cause $1 million in damages
with the probability of one per cent is less
risky than another threat which could
potentially cause $100,000 in damages
with the probability of 50 per cent.
Understanding this definition of
risk is essential. Sometimes, a threat
can seem more significant than it is,
other times it’s grossly underestimated.
The technical definition of the risk, as
noted above, helps to better understand
and prioritize plans. The ISO definition
of risk also touches on the source of
the risk. Uncertainties are the source
of the risk.
Uncertainties which lead to risk
could be caused by natural variation, lack
of understanding, and insufficient or
inaccurate data. There are several types
of risk to a cost-effective and troublefree
project including geotechnical/
environmental risk, inadequate design,
poor planning, poor construction
practices, third party relations and
other subsurface risks (e.g. utilities).
This article focuses mostly on the
geotechnical risk, as one of the most
significant types.
The geotechnical uncertainties
which are the source of geotechnical
risk can be categorized into: natural
complexity and heterogeneity of the
geological environment; testing uncertainty;
estimation uncertainty; and
approximation of engineering models
unattainable. There will always be a
risk of deviation from the objectives.
So, what is risk? People use the
word “risk” with different meanings in
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