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Criticality Matrix (Risk Matrix)
Also referred to as a '"risk matrix".

One of a variety of techniques to help prioritize actions.

A two-dimensional matrix that plots the relationship between the probability of failure (PoF) of an asset (or a future event) and the consequence of failure (CoF) of an asset (or group of assets) at a particular point in time.

The matrix is used in the development of
a criticality analysis.



Horizontal Axis (Probability of Failure)
PoF can be expressed in a variety of linguistic or numerical scales relative to a particular year. Listed below are some examples:
  • Impossible (Extremely unlikely)
  • Remote
  • Possible
  • Probable
  • Frequent (Highly likely)
For example:
  • It is highly likely that our roof will need to be replaced within the next two years
  • It is extremely unlikely that we will need to replace our dry type transformer for at least another 20 years.


Vertical Axis (Consequences of Failure)
Consequence of Failure are measured against categories, such as:
  • Network Performance
  • Safety
  • Environmental
  • Financial - opex and capex


The Scale Index
The combined values of the PoF and CoF are measured from the top-right hand corner of the matrix down to the bottom left corner.

Criticality Index is a numerical representation of criticality on a defined scaled of C1 to C4
.

Listed below is an example of a criticality index applied to a group of assets in buildings
  • Roofs        PoF = 23 and CoF = 84
  • Boilers      PoF = 75 and CoF = 78
  • Carpets     CI = 17
  • Fences     CI = 15

Applications of the Criticality Matrix
A criticality index can be used in the following asset management applications:
Combining Health and Criticality to form an Intervention Priority Index.

"The best way to predict the future is to create it" (Lincoln).  Therefore, it is better for owners to control and mitigate the Probability of Failure (PoF)  of their assets (through maintenance) rather than the Consequences of Failure (CoF) of their assets (through projects).
Risk-based decision making is at the heart of asset management and this requires mindful consideration of the relationship between the probability of failure (PoF) and the consequences of failure (CoF). The complexities of these correlations can sometimes be captured on a risk matrix.
Fig. Risk-based decision making is at the heart of asset management and this requires mindful consideration of the relationship between the probability of failure (PoF) and the consequences of failure (CoF). The complexities of these correlations can sometimes be captured on a risk matrix.



The relationship between Consequences of Failure (CoF) represented on the vertical (y-axis) and Probability of Failure (PoF) on the horizontal (x-axis) of a criticality/risk matrix.
Fig. The relationship between the Consequences of Failure (CoF) represented on the vertical (y-axis) and Probability of Failure (PoF) distributed along the horizontal (x-axis) of a criticality/risk matrix.



Relationship between Probability of Failure (PoF) and the horizontal axis of a risk matrix.
Fig. Relationship between Probability of Failure (PoF) and the horizontal axis of a risk matrix.



I. Care is trying to re-align his building’s magnetic north and thereby use his building as a sundial to cast a shadow to identify all the critical assets
Fig.   I. Care is trying to re-align his building’s magnetic north to geodetic true north and thereby use his building as a sundial to cast the right shadow and identify all the critical assets.


Consequences of Failure (CoF) represented on the vertical (y-axis) of a criticality matrix (risk matrix).
Fig. Consequences of Failure (CoF) represented on the vertical (y-axis) of a criticality matrix (risk matrix).


Risk matrix with tiered consequences of failure.
Fig. Risk matrix with tiered consequences of failure.



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Fig. Example of a matrix of the Health Index (HI) against Criticality Index (CI) for various assets.

See also:


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