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Safety and Reliability of Complex Engineered Systems – Podofillini et al. (Eds)© 2015 Taylor & Francis Group, London, ISBN 978-1-138-02879-1

On the appropriateness of using the ALARP principle in safety management

H.B. AbrahamsenDepartment of Research and Development, The Norwegian Air Ambulance Foundation, Drøbak, NorwayDepartment of Anaesthesiology and Intensive Care, Stavanger University Hospital, Stavanger, Norway

E.B. AbrahamsenUniversity of Stavanger, Stavanger, Norway

ABSTRACT: In this paper we discuss the appropriateness of using the ALARP (As Low As Reasonably Practicable) principle in safety management. We show that ALARP can be an appropriate ruling principle in safety management but only if the grossly disproportionate criterion is interpreted differently for differ-ent decision-making contexts. The ALARP principle should be interpreted such that it ranges from one extreme, where decisions are made with reference to expected values in some decision contexts, to another, in which the cautionary principle is adopted with no reference to cost-benefit analyses for others. A static interpretation of the grossly disproportionate criterion is not appropriate.

take into consideration that the resources available for safety investments are scarce? These questions are the starting point for this paper.

We show that the appropriateness of using the ALARP principle in safety management depends on how ALARP and the grossly disproportionate criterion are interpreted. The ALARP principle is considered an appropriate principle in safety management only if the grossly disproportion-ate criterion is interpreted differently for different decision-making contexts, such that the principle ranges from one extreme, where decisions are made with reference to an expected value, to another, in which the cautionary principle is adopted without any reference to cost-benefit (cost-effectiveness) analyses. A static decision-making principle can-not be appropriate as a ruling principle in safety management as different decision-making contexts require different decision-making principles.

The paper is organized as follows. In Section 2 the attention is on how to implement ALARP and the grossly disproportionate criterion. Then, in Section 3 we discuss the appropriateness of using ALARP as a ruling principle in safety management. Finally, in Section 4 we draw some conclusions.

2 On HOW TO ImPLEmEnT ALARP And THE gROSSLy dISPROPORTIOnATE CRITERIOn

One way to implement ALARP and the grossly disproportionate criterion is by adopting a

1 InTROdUCTIOn

The ALARP principle expresses that the risk should be reduced to a level that is As Low As Reasonably Practicable. This means that a risk reducing measure should be implemented pro-vided it cannot be demonstrated that the costs are grossly disproportionate to the benefits obtained; ref. e.g. HSE (2001) and Vinnem et al. (2006). The ALARP principle gives strong weight to the cautionary principle which is a basic principle in safety management expressing that in the face of uncertainty caution should be the ruling principle (Aven & Vinnem 2007).

In contrast to the ALARP principle one may use expected values as a basis for the decision-making. The justification of using expected values is the portfolio theory. This theory states that the value of a portfolio of projects is equal to the expected value of the portfolio plus the systematic risk (uncertainties) caused by events affecting the whole market (Levy & Sarnat 1990). The unsystematic risk which is related to specific project uncertain-ties can be ignored when the number of projects is large. It then follows that no special weight should be given to the cautionary principle.

With reference to the arguments for using expected values in decision-making under uncer-tainty, we will in this paper discuss what the conse-quences are of using the ALARP principle in safety management. does the ALARP principle lead to an inefficient use of resources? And will the ALARP principle contribute to a reduction in safety if we

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cost-benefit (cost-effectiveness) analysis. The costs can then be defined as grossly disproportionate to the benefits obtained if the expected cost is consid-ered as x times higher than the expected benefit. The value of x is defined by the decision-makers and represents the disproportionate factor. differ-ent values of x can be used for different decision-making contexts.

In the literature it has been pointed out that a traditional cost-benefit (cost-effectiveness) analysis is not appropriate as the only tool for verifying ALARP. The main argument is that the cost- benefit analyses are based on expected values which to a large extent ignore uncertainties which is in contrast to the ALARP thinking (Aven & Abrahamsen 2007).

To better take the uncertainties into considera-tion, a layered approach for implementing ALARP has been suggested by Aven (2011); see also Aven & Vinnem (2007). The approach is shown in Figure 1.

The layered approach consists of three differ-ent steps. In the first step a crude analysis is carried out. According to the approach, the safety measure should be implemented in situations with low costs. Otherwise, one needs to carry out more detailed analyses before a decision is made. From the second step of the approach we see that a safety measure should be implemented according to the ALARP principle if such an investment is appropriate from a cost-benefit (cost-effectiveness) analysis point of view. This is intuitively appealing. One can, for example, not conclude that the costs are grossly disproportionate to the benefits obtained if the expected benefit is higher than the expected costs.

One may also decide to implement a safety measure according to the layered approach even

if the cost-benefit (cost-effectiveness) analysis con-cludes upon no investments. High uncertainties among many other issues can justify investments in a safety measure. This is shown in the third step of the approach.

For a full review of the layered approach we refer to Aven (2011). See also nORSOK Z-013 (2010).

3 HOW mUCH WEIgHT SHOULd BE gIVEn TO THE UnCERTAInTIES In SAFETy mAnAgEmEnT?

different perspectives exist on how much weight that should be given to the uncertainties when decisions are made in safety management. One perspective is to use a traditional cost-benefit (cost-effectiveness) analysis. The decisions are then made with reference to an expected value, which means that limited or no weight is given to the uncertainties.

The appropriateness of using expected val-ues in safety management has been discussed in Abrahamsen et al. (2004). See also Aven (2014) and Aven & Renn (2010). It was argued that expected values are not in general appropriate as a basis for decision-making as the uncertainties are not fully covered. more weight should be placed on the cau-tionary principle than that which is made through expected values.

The above conclusion does not mean that the use of expected values cannot be appropriate to adopt as a basis for decision-making. The main message is that expected values cannot be appro-priate to use as a general decision-making principle in safety management. There are, for example, no arguments for not making decisions with respect to expected values in situations with high knowl-edge and low uncertainties. Stronger weight to the cautionary principle than that which is supported by an expected value approach will, for such deci-sion contexts, just lead to an inappropriate use of resources.

In the following we refer to the use of expected values as an extreme economic perspective on how to weight the uncertainties in safety management. It is referred to as an extreme economic perspective as we have to acknowledge that the cost-benefit (cost-effectiveness) analyses we use for computa-tion are far from perfect, and the mechanical appli-cation of the results can give decision-making with a strong element of arbitrariness (Abrahamsen et al. 2011).

Another perspective on how to weight the uncer-tainties in safety management, which is in contrast to the extreme economic perspective, is to give strong weight to the cautionary principle without

Figure 1. Layered approach for implementing ALARP and the gross disproportionate criterion (Aven 2011).

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any references to cost-benefit (cost-effectiveness) analyses. Such a perspective is referred to as an extreme safety perspective in the following.

In situations with extreme risk and/or extreme vulnerability one may consider it appropriate to make decisions with reference to the extreme safety perspective, where no attention is given to costs and benefits. We do not consider the extreme safety perspective an appropriate principle in gen-eral as such a perspective turns out not to be cost-effective.

A third category of perspectives on how to weight the uncertainties lies somewhere between the two extremes.

From the above we have seen that different perspectives exist on how to weight the uncertain-ties. But which is the most appropriate to adopt in safety management?

Well, it depends on the decision-making con-text. One single perspective on how to weight the uncertainties cannot be appropriate to adopt for all decision contexts. different contexts require dif-ferent decision-making principles. Similar conclu-sions are also found in e.g. Wiencke et al. (2006) and Abrahamsen et al. (2015). This means that it cannot be appropriate to use the ALARP principle as a general principle in safety management unless it is interpreted in a dynamic way, meaning that the interpretation of the grossly disproportion-ate criterion ranges from one extreme perspective, where decisions are made with reference to a tradi-tional cost-benefit (cost-effectiveness) analysis, to another, in which the cautionary principle is given strong weight without any reference to cost-benefit (cost-effectiveness) analyses.

A discussion upon the appropriateness of using ALARP as a general principle in safety manage-ment can then not be made without referring to how this principle is implemented.

As described in the previous section, one way to implement ALARP is to define costs as grossly disproportionate to the benefits obtained if the Expected Cost (EC) is considered x times higher than the Expected Benefit (EX), where x repre-sents the grossly disproportionate factor between the costs and benefits. This approach for imple-menting ALARP is considered inappropriate if one value of x is used for all types of decision con-texts, as, in this way, the ALARP principle turns out to be static.

The ALARP principle will be dynamic with the above approach if different values of the grossly disproportionate factor are used for different decision contexts. But, as described in the previ-ous section, such an approach is not considered appropriate, as focusing solely on expected val-ues does not take the uncertainties properly into consideration.

The approach we consider as the most appro-priate for implementing ALARP is the layered approach shown in Figure 1. There are two rea-sons for this. Firstly, the uncertainties are better taken into consideration in the layered approach than for approaches focusing solely on expected values. Secondly, the ALARP principle is dynamic if the layered approach is adopted, which means that different weight is given to the uncertainties for different decision-making contexts. The weight given to the uncertainties is a management task within the layered approach, but support upon this issue is given through a checklist (guideline). This means that the ALARP principle does not neces-sarily range from one extreme perspective on how to weight the uncertainties to another if the lay-ered approach is adopted.

From this point of view we cannot conclude upon the appropriateness of using the ALARP principle as a general decision-making principle in safety management if the layered approach is adopted. We also need to look more closely into how the checklist (guideline) within the approach is formulated.

We consider the ALARP principle to be an appropriate principle to use in safety manage-ment in general if the layered approach is adopted, but only if the checklist (guideline) contributes to the ALARP principle’s ability to range from an extreme economic perspective on how to weight the uncertainties to an extreme safety perspective. The main point is that the extreme perspectives on how to weight the uncertainties are appropriate to use in some decision contexts. Without cover-ing these extremes, the ALARP principle cannot be appropriate to use as a general decision-making principle in safety management.

In Figure 2 we have redrawn the approach from Figure 1 to make it clearer that the ALARP prin-ciple, by the layered approach, can range from one extreme perspective on how to weight the uncer-tainties to another extreme.

The approach for implementing the ALARP principle consists of two main steps, as shown in Figure 2. The first step will not be given further attention as it is equal to the first step in Figure 1. The second step of the approach consists of two different parts. In the first part, the decision con-text is classified with reference to the same issues as assessed in the third step of the layered approach in Figure 1. In the second part, the guideline gives support regarding which perspective is the most appropriate for the various decision contexts.

How the guideline is formulated is a manage-ment task, but the guideline should open up the way for making decisions with respect to both the extreme economic perspective and the extreme safety perspective as argued for above.

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Figure 2. An alternative visualization of the layered approach for implementing the ALARP principle.

The guideline can be carried out such that the ALARP principle turns out to be equal to a tra-ditional cost-benefit (cost-effectiveness) analysis as long as all the issues assessed are considered unproblematic (low uncertainty, best available tech-nology, etc.). This means that, for such contexts, we define the costs as grossly disproportionate to

the benefits obtained if the expected cost is higher than the expected benefit.

In decision contexts where all the issues are considered problematic (high uncertainty, the best available technology is not used, etc.) one may adopt the extreme safety perspective. For all other decision contexts one may adopt a perspective

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which is somewhere between the two extremes. One may also define the guideline such that the extreme economic perspective and the extreme safety perspective can be appropriate to adopt for other contexts than those described above.

In the way the layered approach is presented in Figure 1 it is difficult to see that the ALARP prin-ciple can be as dynamic as shown in Figure 2. To see this more clearly, one may look more closely into situations where all the issues assessed in the third step of the approach are considered unprob-lematic. One may then conclude upon ‘no imple-mentation’ even if the expected cost of the safety measure is just slightly higher than the expected benefit. The decision is then based solely on a tra-ditional cost-benefit analysis. The checklist may also be carried out such that the decision for some decision contexts is to implement the safety meas-ure independent of the result from the second step of the approach, which means that the ALARP principle turns out to be equal to the extreme safety perspective.

4 COnCLUSIOnS

In this paper we have shown that the ALARP prin-ciple is not considered appropriate as a general decision-making principle in safety management unless it is interpreted in a dynamic way, meaning that the interpretation of the grossly dispropor-tionate criterion ranges from one extreme, where decisions are made with reference to expected val-ues, to another extreme, in which the cautionary principle is given special weight with no reference to cost-benefit (cost-effectiveness) analyses.

The main point is that one static decision-making principle cannot be appropriate to use for all decision contexts. different contexts require different decision-making principles. It then follows that it is not appropriate to use the ALARP principle in safety management as a general decision-making principle if the costs are defined as grossly disproportionate to the ben-efits gained independent on the decision-context. Further on, we conclude that it can be appropri-ate to adopt the ALARP principle as a general principle in safety management if the layered approach suggested by Aven (2011) is adopted. This approach is formulated in such a way that the ALARP principle can range from one extreme perspective, where decisions are made with refer-ence to expected values, to another extreme, in which the cautionary principle is given special

weight with no reference to cost-benefit (cost-effectiveness) analyses.

ACKnOWLEdgEmEnTS

The work has been funded by the norwegian Research Council of norway through the Petro-maks 2 programme. The support is gratefully acknowledged.

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