Ranking Risk

Once all the steps and all the risks have been identified the risks needs to be analyzed in order to establish the priority of future actions as well as the sequence and extent of these actions.

The purpose of analyzing the risk is purely to objectively establish the priority of the actions required in order to reduce identified risks to tolerable levels.

It should be noted that if this part is neglected, the rest of the risk assessment and the decisions made upon it could be totally invalid.

Experience indicates that, if one is not careful, this section can unnecessarily take up the bulk of the time required to conduct risk assessments. This should be avoided at all cost as the calculations per se is not important, it is more important to be consistent than to be absolutely accurate during this phase.

At this stage the team will have a long list of potential problems (risks), each with an individual risk ranking. The facilitator should lead the team through a discussion of all the potential problems that have significant risk rankings, starting with those with the highest rank (i.e. the most serious risks). The actual risk ranking value will vary from mine to mine as differences in the risk analysis methodologies may exist.

Qualitative versus Quantitative Methodologies

The workplace risk assessment is a specific qualitative risk assessment method designed to be applied when an organization wants to understand its risks and clearly identify the priority or highest risks in its operation. It is a method particularly suited to operator-critical and people-intensive workplaces because it reviews operator actions, while other methods may be more process and equipment orientated.

Risk ranking as part of a workplace risk assessment is not a quantitative risk assessment technique in that it utilises qualitative risk assessment methodologies. Qualitative methods of assessing risks do not try to establish numbers and "black and white" tolerability of risk like quantitative risk assessments. Qualitative risk assessment attempts to establish levels of risk only in relation to other risks, or a total system risk. As such, methods such as risk ranking are commonly used to establish relative levels of risk, ranging from a high rank to a low rank.

The Dimensions for Ranking

Traditionally it was considered sufficient to consider the potential severity and frequency of a risk in order to rank it. The introduction of the duty of care into legislation, however, requires that the exposure of the workforce to the risk should also be considered during the evaluation phase.

This implies that the simple risk matrix currently in use by many organizations would be very difficult to use, as three dimensions of the risk should be considered.

It is also important to consider that all the dimensions do not have the same weighting. In most cases it would appear that severity has a higher weighting than frequency and that frequency in turn has a higher weighting than exposure. In addition to this it is clear that the scales used in matrices very seldom have a linear function, with the exception of the exposure that is normally expressed as a percentage and normalized for duration of exposure.

The impact normally results in the consequence. Impact, in general, can refer to the influence or effect of an energy source on an object. In science, however, it can refer to the collision of two objects.

At energy levels that are under control, during a controlled collision, an object struck by another will deform, and this deformation will absorb most, or even all, of the force of the collision. Viewed from the conservation of energy perspective, the kinetic energy of the objects are changed into heat and sound energy, as a result of the deformations and vibrations induced in the struck object. However, these deformations and vibrations can not occur instantaneously. A high energy impact may not provide sufficient time for the energy to be absorbed and will result in a consequence.

The consequences we are interested in are those that result in a negative outcome. This can include physical injuries to people, damage to tools and equipment or any other defined negative consequence. In summary the factors we should consider includes:

The nature of incident, which includes any consequence from multiple fatalities through serious disabling incidents resulting to first aid treatment required.

The nature of property damage to be considered can include a devastating property loss right down to insignificant property loss resulting from the risk being realised.

The analysis of the three dimensions could take place as follows:

First the team should determine the potential severity of the risk on a scale similar to the following:

• Catastrophic

• Critical

• Serious

• Marginal

• Negligible

This scale can be allocated the following values 64, 32, 16, 8 and 4 each value representing one of the points on the scale.

When determining the frequency of occurrence it is important to link the consequence with the specific risk. In other words the team should determine how frequent a specific consequence will result form the risk being assessed.

As this is a qualitative assessment it is unnecessary to put real values to the grading. The key to success is consistency rather than exactness of allocating a frequency.

The second step in this part of the process is to determine the potential frequency of the risk on a scale similar to the following:

• Frequent

• Regular

• Occasional

• Uncommon

• Slender

It should be noted that a frequency as implicated above is a rate of recurrence and is not the same as probability. With probability is meant the statistical possibility of the risk resulting in a consequence. This is a quantitative value that should not be used in a qualitative assessment.

The third step is to determine the potential exposure of the risk on a scale similar to the following:

For safety purposes the following guide should be used to determine the exposure level as follows.

Determine the Percentage of the work force that is exposed to the risk

• Extensive 80% - 100%

• Widespread 60% - 80 %

• Significant 40% - 60%

• Restricted 20% - 40%

• Negligible 1% - 20

The percentage should be normalised for duration of exposure of the workforce. In other words if 60% of the workforce is exposed to a particular risk for four of the eight hour shift, it implies that a 30% ranking is obtained, resulting in the assessor to select a Restricted exposure on the above scale.

There are several approaches which can be used for the measurement of risk.

Once all the values have been identified it is a simple matter of converting the three values to a risk ranking.

The approach to risk measurement does not have to be complex or sophisticated. It should be sufficient to allow good decisions to be made, with confidence, and in a form that can be communicated to employees, inspectors and to other stakeholders to demonstrate competent and responsible management.

One way of determining the risk ranking is to multiply the severity with the frequency with the exposure. To do this each of these factors should be allocated a value. Please note that when using this approach, the higher the risk ranking value obtained, the higher the priority to deal with the risk.

Another way of determining the risk ranking is to make use of a risk matrix.

When using this approach the team should categorize the consequences of the hazard and its frequency separately and then combine these in a matrix to determine the risk ranking. The two-dimensional risk ranking matrix can now be translated into a three-dimensional ranking system by making use of a second matrix where the consequence/frequency index, determined in the first matrix is combined in a second matrix with the exposure of the workforce to the specific risk.

Conclusion to Risk Ranking

On its own the risk ranking numbers are pretty useless. The purpose of conducting the risk assessment is to draw up a risk profile of the workplace. To achieve this all the risk rankings should be reflected on a risk profile chart.

A word of warning, should all the values come out to be very similar (all very high or very low) the team probably did not analyse the risks properly. It is a known fact that not all risks have the same potential consequences.

It is particularly important that the assessment is objectively conducted. For this reason the team approach is very valuable.

An objective evaluation is one which attempts to capture the risk of the hazard being evaluated in a way that is independent of the personal views of the individuals who form part of the team. An objective assessment is, in this sense, impartial, one which could ideally be reached by any team, because it does not draw on any assumptions, prejudices, or values of particular subjects.

On its own the risk ranking numbers are pretty useless. The purpose of conducting the risk assessment is to draw up a risk profile of the workplace. To achieve this all the risk rankings should be reflected on a risk profile chart. This type of chart may have a number of different layouts or designs. One way is to reflect the risk ranking chart in a bar chart style chart.

Another way to display the risk ranking is by making use of colors where red could be the highest and blue the lowest. This is often also combined by a difference in the size of the pie chart.

© 2009 Carl Marx