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PRACTICAL WORK №2

ENGINEERING METHOD OF RISK DETERMINATION

1 OUTCOMES
Become familiar with the engineering method of risk determination

2 DURATION OF CLASS
The class duration is two academic hours

3 BASIC THEORY
3.1 Engineering method of risk determination
Risk is the frequency of hazard implementation. The risk is the criterion of
hazard implementation and it is determined by the probability of its manifestation
and the probability of human presence in a dangerous zone.
Engineering method of the risk determination is based on statistics and the
calculation of frequency of hazard manifestation. According to this method the

value of risk R is determined by the ratio of the number of unwanted cases m a
dangerous event A to the total number of possible cases n:
R  P  A  m , (2.1)


  n
where P(A) – probability of the event A.
The formula allows you to calculate the value of total and group risk. When
evaluating the total risk value n specifies the maximum number of all events, and
when evaluating the group risk– the maximum number of events in a particular
group, selected from the total number of a certain feature. In particular, the group
may include people, who belong to the same profession, age, sex, the group may
include vehicles of the same type, one type of business entities etc.
Individual risk informs about the spreading of risk as a possible defeat of a
particular or a typical individual in a certain point in space under a certain impact.
It may be calculated in the manner of multiplying of the frequency of
implementation of hazard with fatal consequence and employment factor showing
in fractions a unit of time of an individual staying in a dangerous zone.
The essence of the concept of a reasonable (acceptable) risk consists in the
desire to establish such a level of safety that a society can let at this stage of its
development, taking into account technical and economic, and social opportunities.
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Nowadays the fixed (acceptable) value risk in the world practice is 10 .
The events can be:
1) compatible and incompatible.
Compatible events are such events, which may occur together,
simultaneously, and incompatible events do not occur together.
Addition theorem for compatible events is:

P A  В  P   PА    PВ   * ВA , (2.2)

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