Chapter 5
Cost-Benefit Analysis

5.1 An Introduction to Cost-Benefit Analysis

A cost-benefit analysis (CBA) is an economic evaluation in which all costs and consequences of a certain decision are expressed in the same units, usually money [1]. Such an analysis may be employed in relation to operational safety, to aid normative decisions about safety investments. One should keep in mind, however, that CBAs cannot demonstrate whether one safety investment is intrinsically better than another. Nevertheless, a CBA allows decision-makers to improve their decisions by adding appropriate information on costs and benefits to certain prevention or mitigation investment decisions. As decisions on safety investments involve choices between different possible risk management options, CBAs can be very useful. Moreover, decisions may be straightforward in some cases, but this may not always be true. Especially in the process industries or the nuclear sector, for instance, where there are obviously important type I as well as type II risks that should be managed and controlled, and a variety of both of them, risk management options may be difficult and not at all obvious. Moreover, CBA is not a pure science and sometimes needs to employ debatable concepts, such as the value of human life (see also Chapter 4), the value of body parts, the question of who pays the prevention costs, and who receives the safety benefits.

There are two types of CBA. On the one hand, it is possible to carry out a so-called “ex ante CBA,” in order to verify whether a certain investment is worthwhile. On the other hand, a so-called “ex post CBA” can be carried out at the end of a project to evaluate the financial achievements accompanying the project [2]. Although, in this chapter, we are mainly interested in an ex ante CBA, whereby safety managers may carry out an economic exercise and thus simulate and assess the financial soundness of the implementation of safety and prevention measures, the technique described further in this chapter can also be used to carry out an ex post CBA. There are, however, several reasons why we focus on ex ante analysis in this book. An important reason why companies should consider executing CBAs for the evaluation of prevention investment decisions is that such analyses can help employees to convince managers of the importance of safety measures from an economic point of view. In addition, a CBA can also help managers in the efficient allocation of a safety budget, as some safety measures may turn out to be more efficient than others, when dealing with identical, similar or comparable risks. In any case, it should be borne in mind that the result of any CBA, being a recommendation for a prevention investment decision, is meant merely to assist the decision-maker in the decision process by making costs and benefits more transparent and more objective.

The decision-maker is thus recommended to use this approach with caution, as the available information is subject to varying levels of quality, detail, variability, and uncertainty. Nevertheless, the tool is far from unusable and can provide meaningful information for aiding decision-making, especially if it takes the levels of variability and uncertainty into account and thus avoids misleading results.

From the previous, it is clear that CBAs can be used to determine whether an investment represents an efficient use of resources. A safety investment project represents an allocation of means (money, time, etc.) in the present that will result in a particular stream of non-events, or expected hypothetical benefits, in the future. The role of a CBA is to provide information to the decision-maker, in this case an employee or a manager who will appraise the safety investment project. The main purpose of the analysis is to obtain relevant information about the level and distribution of benefits and costs of the safety investment. Through this information, an investment decision within the company can be guided and made more objective. The role of the analysis is thus to provide the possibility of a more objective evaluation and not to adopt an advocacy position either in favor of or against the safety investment, as there are also many other aspects that should be taken into account when deciding about safety investments, such as, for example, social acceptability and regulatory affairs.

The costs and benefits of a safety investment project within an organization include those affecting the financial position of the company in the broadest sense possible. This means that all claims resulting from damage to society and others are included, but damage to society and others for which there will be no claims whatsoever from the company are excluded. There is no doubt that type II accidents, for example, have wider implications on society, but if these would (theoretically) not affect the firm's financial position in any way, they are omitted from the CBA helping the company's safety decision-making process.

A safety investment project makes a difference, as the future will be different depending on whether the company decides to invest or not, or to invest in an alternative investment option. Thus, in the CBA, two hypothetical worlds are envisaged: one without the safety investment, and another with the safety investment. During a CBA, a monetary value is put on the difference between the two hypothetical worlds. This process is shown in Figure 5.1.

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Figure 5.1 Cost-benefit analysis process for safety investments.

As a safety investment project involves costs in the present and both costs and benefits in the future, the net benefit stream will be negative for a certain period of time and will then become positive at a certain point in time. This should be the case for both type I and type II risks, but the manner in which the calculations are performed differ. Therefore, a distinction between both types of risks is made later in this chapter.

5.2 Economic Concepts Related to Cost-Benefit Analyses

5.2.1 Opportunity Cost

An important concept in economics is the existence of “opportunity costs.” In this book on operational safety economics, this concept dictates that if a budget is spent on a certain safety investment, it is no longer available and thus cannot be spent on another safety investment, or a financial investment for that matter. As the resources will have been used, they are now unavailable for use in other safety tasks, measures or any kind of investment. This implies that any hypothetical benefits arising from the use of other (e.g., safety) investments, besides the one that the company decides to invest in, have to be forgone. This is called the “opportunity cost” of the investment decision. In economic language, an opportunity cost can be defined as “the amount lost by not using the resource (labor or capital) in its best alternative use” [3]. Regarding safety, it is obviously very difficult to measure all the forgone hypothetical benefits in reality, but the concept of opportunity costs offers a useful guide in thinking through decisions to the very end, as it explicitly shows the trade-offs that have to be made when allocating resources in operational safety.

5.2.2 Implicit Value of Safety

One of the trade-offs that have to be made is a budget allocation between prevention of type I risks and prevention of type II risks.

In fact, making a budget allocation choice for type I risks and type II risks unavoidably leads to placing a value on safety, human life or a related parameter. So even if one objects on principle to the valuation of safety, or human life, it is often unavoidable when business decisions have to be made [4].

5.2.3 Consistency and Uniformity of Safety Investment Decisions

A difficulty of safety investment decision-making has to do with establishing consistent safety performance across different plant units or facilities: the implementation of uniform operational safety standards in every case may not lead to an efficient method of resource allocation. In fact, using uniform operational safety standards may give rise to differences in the implicit value of safety within different organizational contexts and could lead to suboptimal safety investments.

In summary, the implementation of uniform operational safety standards for both types of risk in every case may not create an optimal method of resource allocation and safety managers therefore need to calculate optimal budget allocations for type I and type II risks based on organization-specific characteristics.

5.2.4 Decision Rule, Present Values, and Discount Rate

If a company uses a CBA, the recommendation of whether to accept or reject an investment project is based on the following process:

  1. 1. identification of costs and benefits;
  2. 2. calculation of the present values of all costs and benefits;
  3. 3. comparison of the total present value of costs and the total present value of benefits.

In order to compare the total costs and the total benefits, comprising the costs and benefits occurring at different points in time, one needs to take a discount rate into account in the calculation to obtain the present values. Thus, during a CBA, all cash flows, from both costs and benefits in the future, need to be converted to values in the present. This conversion is carried out by discounting the cash flows by a discount rate. The discount rate represents the rate at which people (or companies) are willing to give up consumption in the present in exchange for additional consumption in the future. Another definition is that in a multi-period model, people value future experiences to a lesser degree than present ones, as they are sure about present events and unsure about future events, which are subject to the environment. Thus the higher the discount rate they choose, the lower the present values of the future cash flows [5].

An investment project is recommended when the total net present value (NPV) of all cash flows is positive, and an investment project is usually rejected when the NPV is negative. To calculate the NPV related to project management, all cash flows are determined, and future cash flows are recalculated to today's value of money by discounting them by the discount rate. The formula usually quoted to calculate the NPV is:

where c05-math-0002 represents the cash flow in year c05-math-0003, c05-math-0004 is the time period considered (usually expressed in years), and c05-math-0005 is the discount rate.

Applied to operational safety, the NPV of a project expresses the difference between the total discounted present value of the benefits and the total discounted present value of the costs. A positive NPV for a given safety investment indicates that the project benefits are larger than its costs.

equation

where

  1. If NPV ≥ 0, recommend safety investment;
  2. If NPV < 0, recommend to reject safety investment.

It is evident that the cash flows, i.e., prevention costs and certainly expected hypothetical benefits (due to non-events), may be uncertain. Different approaches can be used in this regard. The cash flows can, for example, be expressed as expected values, taking the uncertainties in the form of probabilities into consideration, and also increasing the discount rate to outweigh the possibilities for unfavorable outcomes. In case of type II risks, it is recommended to use scenario analyses, determining expected cash flows for different scenarios (e.g., worst-case and most credible case) and using a disproportion factor (DF) (see Sections 4.11.2.1, 5.4.2.2, and 8.12).

There can be different categories of costs related to a safety investment, e.g., initial costs, installation costs, operating costs, maintenance costs, inspection costs . These costs are clearly represented by negative cash flows. Some costs (e.g., initial costs and installation costs) occur in the present and thus do not have to be discounted, while other costs (e.g., operating, maintenance, and inspection costs) occur throughout the remaining lifetime of the facility and will thus have to be discounted to the present. There may also be different categories of benefits linked to a safety investment, such as supply chain benefits, damage benefits, legal benefits, insurance benefits, human and environmental benefits, intervention benefits, and reputation benefits, among others. The benefits represent positive cash flows, which all occur throughout the remaining lifetime of the facility and thus will all have to be discounted to the present.

In order to clarify the discount rate principle, all cash flows (for both costs and benefits) are assumed to occur on an arbitrarily chosen date, which can, for example, be chosen to be the last day of the calendar year in which they occur. This assumption converts the continuous cash flows to a discrete range of cash flows, occurring at the end of each year. The cash flows at the end of each year then have to be discounted to a present value, using a discount factor. As stated before, cash flows occurring in the current year do not have to be discounted. Therefore the current year is called “year 0,” and the following years “year 1,” “year 2,”…, “year c05-math-0007.” Costs and benefits occurring in year 1 are discounted back one period, those occurring in year 2 are discounted back two periods, and those occurring in year c05-math-0008 are discounted back c05-math-0009 periods. The implicit assumption is made that the discount rate remains the same throughout the remaining lifetime of the facility [5].

Thus, to calculate the present value of a benefit occurring in year 1, it needs to be discounted for one period to come to a present value in year 0. Similar to the calculation of a benefit occurring in year 1, the present value of benefits occurring in years 2 and 3 are obtained by discounting them two and three periods, respectively. Similar to the previous calculations, the present value (PV) of a benefit occurring in year n is obtained by discounting it over n periods. These calculations can be found in the following range:

equation

Now that the concept and method of discounting future cash flows have been clarified, suppose a safety investment project has a cost in year 0 and then the same level of costs and benefits at the end of each and every subsequent year for the remaining lifetime of the facility. This means that the costs in year c05-math-0011 are the same for all c05-math-0012, i.e., c05-math-0013; likewise, the benefits in year c05-math-0014 are the same for all c05-math-0015, i.e., c05-math-0016. This concept is called an “annuity.” The present value (PV) of such an annuity is given by the following formula, with c05-math-0017 being the remaining lifetime of the facility:

c05-math-0020 and c05-math-0021 are the equal annual costs (cost categories where costs are made in the future) and benefits (all benefits categories), respectively, that occur at the end of each year, and are assumed to remain constant. This assumption is valid as long as inflation is omitted from the calculations and as long as the annual costs are assumed not to increase over time due to aging. These assumptions keep the caluculations simple while explaining the cost-benefit approach. Each term in the formula is formed by multiplying the previous term by c05-math-0022. As the above formulas can become very long, the formula for calculating the present value of annuities can be rewritten, by way of the series solution

equation

as

equation

where c05-math-0025 is the yearly cost or benefit of a cost-benefit category. Note that this general annuity goes to c05-math-0026 as the discount ratio c05-math-0027 goes to zero. The term

of the series solution is called “the annuity (discount) factor” and is applicable whenever the annuity starts from year 1 [5].

Using this model, the benefits and costs in the future are assumed to be constant, and inflation is not included into the future costs and benefits, as already mentioned. Inflation is the process that results in a rise of the nominal prices of goods and services over time. Therefore in this (simplified) model, the real rate of interest1 should be used as the discount rate instead of the money rate of interest.2 As the money rate of interest, m, includes two components, the real rate of interest, r, and the anticipated rate of inflation, i, the anticipated rate of inflation is built into the money rate of interest:

equation

As inflation is not included in the numerator of the formula for calculating the present value of annuities (as the costs and benefits are constant throughout the whole remaining lifetime), it cannot be included into the denominator.

5.2.5 Different Cost-Benefit Ratios

Several approaches are possible for presenting the cost-benefit principle, and different cost-benefit ratios can be calculated. Notice that sometimes benefits are divided by costs, in which case a benefit–cost ratio is obtained, and sometimes costs are divided by benefits, giving a cost-benefit ratio. In the case of a benefit–cost ratio, the ratio should ideally be higher than 1, and as high as possible, while in the case of a cost-benefit ratio, it should ideally be lower than 1, and as low as possible. The following ratios are mentioned by Fuller and Vassie [4]:

  1. Value of an averted loss:
    equation
  2. Value of equivalent life:
    equation
  3. Value of risk reduction:
    equation

5.3 Calculating Costs

The purpose of implementing operational safety measures is to reduce present and future operational risks. By “reducing the risk,” the prevention of accidents is indicated, as well as the mitigation of consequences if an accident were to occur after all. Safety measures can be costly. Before discussing the different cost factors of implementing safety measures, different types of measures are briefly discussed.

5.3.1 Safety Measures

There are four different classifications into which safety measures can be divided. First, risk reduction measures can be classified into protection and prevention measures, depending on their characteristics. Protection measures (including mitigation measures) lower the consequences, while prevention measures decrease the probability of an accident (see also Meyer and Reniers [6]). Second, safety measures can also be classified into active or passive systems according to what is necessary to be able to perform their function. Third, a classification can be made according to their impact on the severity and probability of occurrence; of the many safety measures, only some of them will, for example, play a role in the prevention of catastrophic or disastrous events. There may sometimes be a need, therefore, to focus the efforts and identify priority safety elements. The third classification of safety measures is thus into safety measures and safety-critical measures. Fourth, safety measures can be looked at from three dimensions: people, procedures, and technology. The interplay among people, procedures and technology safety measures defines the observable part of the safety culture in an organization [see also the safety culture egg model (The Egg Aggregated Model) from Chapter 2].

5.3.2 Costs of Safety Measures

As stated earlier, in order to be able to implement new safety measures and upgrade existing safety systems, a company has to reserve substantial funding. In this section, the various costs related to new safety measures that a company may decide to implement are discussed. Table 5.3 provides a clear overview of the different kinds of costs of safety measures.

Table 5.3 Cost categories of safety measures

Type of safety cost Subcategory of safety cost
Initiation (Section 5.3.2.1) Investigation
Selection and design
Material
Training
Changing guidelines and informing
Installation (Section 5.3.2.2) Production loss
Start-up
Equipment
Installation team
Operation (Section 5.3.2.3) Utilities
Maintenance (Section 5.3.2.4) Material
Maintenance team
Production loss
Start-up
Inspection (Section 5.3.2.5) Inspection team
Logistics and transport safety (Section 5.3.2.6) Transport and loading/unloading of hazardous materials
Storage of hazardous materials
Drafting control lists
Safety documents
Contractor safety (Section 5.3.2.7) Contractor selection
Training
Other safety (Section 5.3.2.8) Other prevention measures

For each of the costs mentioned in Table 5.3, formulas are elaborated to calculate every subcategory of costs.

5.3.2.1 Initiation Safety Costs

Under the initiation costs of safety measures, five different kinds of safety costs can be grouped:

  1. 1. Investigation safety costs
  2. 2. Selection and design safety costs
  3. 3. Material safety costs
  4. 4. Training safety costs
  5. 5. Changing guidelines and informing safety costs.

These costs will not have to be discounted to present values, as they will occur in the present (hence in the basic year, year 0). Each of the different types of costs is explained more in depth in the following sections.

Investigation Safety Costs

The investigation, carried out by the so-called “investigation team” studying the potential of a safety project, brings with it costs related to the investigation and audit activities, internally (the health and safety department of the company) or externally, or both. The purpose of this effort is to check whether additional safety measures or upgrades to the existing safety system are possible and necessary. The costs can be estimated and/or calculated by multiplying the hourly wage of an employee by the number of hours the investigation/audit takes, and again by the number of employees participating in the investigation or audit. If, however, employees with significantly varying wage levels participate, the investigation team costs can be calculated separately for each category of employees. Another possibility is to take the average wage level of all employees participating, in order to simplify the work and only have to work with one category.

This calculation is represented by the following formula:

equation

where c05-math-0045 is the number of employee categories.

Selection and Design Safety Costs

If the investigation or audit suggests that upgrades in the safety system are possible or necessary, a prevention and/or mitigation measure will have to be selected and designed. Such a measure is, of course, accompanied by costs, which can be calculated by multiplying the hourly wage of all employees involved by the number of hours they work on the design, and then again multiplying by the number of employees participating. They can also be calculated separately for categories of employees with varying wage levels.

This calculation is represented by the following formula:

equation

where c05-math-0057 is the number of employee categories.

Material Safety Costs

The actual safety measure, and the components that constitute it, also sometimes requires a budget (e.g., in case of a dyke that needs to be built around a storage tank). The material costs and costs related to the creation of the safety measure can be calculated by multiplying the price per unit of the necessary materials by the number of units the company requires to create the safety measure.

This calculation is represented by the following formula:

equation

where c05-math-0067 is the number of different materials.

Training Safety Costs

In order to calculate these safety costs, the assumption is made that the company provides training to its employees working in the facility related to the new safety measure. It is assumed that some employees or external consultants or coaches will be given the task of disseminating the necessary information and explaining how to work with the new safety measure and how to handle it properly in the case of an emergency. The costs arising because of this assignment to some employees or external consultants or coaches can be calculated and estimated by multiplying the hourly wage of an employee by the number of hours this process takes, and again by the number of employees participating in the assignment. If, however, employees with significantly varying wage levels participate, the training costs can also be calculated separately for each category of employees. Another possibility is to estimate the costs by taking the average wage level of all employees participating, so you only have to work with one category.

This calculation is represented by the following formula:

equation

where c05-math-0079 is the number of employee categories.

Changing Guidelines and Informing Safety Costs

In order to calculate the costs resulting from the required changes to guidelines and the necessary disseminating activities, the assumption is made that in addition to training, the company will inform the personnel of the new safety measure through some kind of brochure, newsletter, or guide. This brochure will also contain the altered guidelines and safety instructions. These costs can be calculated by multiplying the price per unit of brochures/guides by the number of them needed. One unit can, in this case, either represent one brochure or a pack of brochures that may contain, for example, 100 brochures. This will depend on which price is used, the price per brochure or the price per batch of brochures (procedures).

This calculation is represented by the following formula:

equation

where c05-math-0089 is the number of different brochures.

5.3.2.2 Installation Safety Costs

The installation safety costs are made up of different sub-costs:

  1. 1. Production loss safety costs
  2. 2. Start-up safety costs
  3. 3. Equipment safety costs
  4. 4. Installation team safety costs.

Similar to the initiation safety costs, the installation safety costs will not have to be discounted to present values, as they will occur only in the present (hence in the basic year, year 0). Each of the different types of costs is explained in more depth in the following sections.

Production Loss Safety Costs

When a safety measure is implemented, in some cases the production has to be stopped temporarily, resulting in a production loss. This production loss is accompanied by costs because of the non-producing status of the facility or installation. Production loss safety costs can be calculated by multiplying the production capacity/rate of the facility by the duration of the stop, and again by the profit per unit sold [7].

This calculation is represented by the following formula.

Start-up Safety Costs

The implementation of a new safety measure can cause a temporary slowdown in production due to the required restart of the facility (because of the required production halt due to safety measure implementation). The costs related to the temporary slowdown in production for safety-related reasons are called start-up safety costs and can be calculated by multiplying the difference in production rate before and after the halt in production by the duration from the time the production line is reactivated after the implementation of the new measure to the time it returns to the initial production rate, and again by the profit per unit sold [7].

This calculation is represented by the following formula.

Note that if the production rate at the time of the start-up is exactly the same as the production rate before the halt in production, the start-up safety costs will be zero.

Equipment Safety Costs

The installation of a new safety measure usually requires equipment (to be bought or rented). Equipment indicates all kinds of working tools, but also, for example, machinery and modes of transportation. These equipment costs can be calculated by multiplying the price per unit of the equipment by the units needed to install the safety measure.

This calculation is represented by the following formula:

equation

where c05-math-0108 is the number of different equipment categories.

Installation Team Safety Costs

The installation team safety costs are related to the employees who are installing the new safety measure in the facility. These can be calculated and estimated by multiplying the hourly wage of the participating employees by the number of hours the installation takes, and again by the number of employees involved. If employees with significantly varying wage levels are involved, the installation team costs can be calculated separately for each category of employees. Another possibility is to take the average wage level of all employees participating, and thus work with just one category.

This calculation is represented by the following formula:

equation

where c05-math-0120 is the number of employee categories.

5.3.2.3 Operation Safety Costs (Utilities)

Utility safety costs will have to be discounted to present values, as they will not only occur in the present (i.e., in the basic year, year 0), but throughout the remaining lifetime of the facility. Active safety systems, for example, need energy sources and other utilities external or internal to the system to perform their function. Without these utilities, the active safety system will not be able to function. Examples of external energy sources include electric power, hydraulic power, manpower, and system pressure. In a CBA, one may choose to calculate the annual utility safety costs by multiplying the price per unit of a utility by the units needed per year.

This calculation is represented by the following formula:

equation

where c05-math-0130 is the number of different utility categories.

The assumption is made that the utility safety costs represent the same level of costs at the end of each year for a specific time interval. As mentioned earlier, the cost stream c05-math-0131, c05-math-0132,…,c05-math-0133, where c05-math-0134 the remaining life span of the facility in years, and c05-math-0135 for all c05-math-0136, is termed an annuity. The total present value is not just the sum of the utilities' costs for each year, such as was calculated in the previous cost sections, because the utilities' costs occur throughout the remaining lifetime of the facility and thus have to be calculated taking into account a discount factor. The total present value is given by the formula in the following box, as discussed in Section 5.2.4, (Eq. (5.4)).

5.3.2.4 Maintenance Safety Costs

  1. 1. Material safety costs
  2. 2. Maintenance team safety costs
  3. 3. Production loss safety costs
  4. 4. Start-up safety costs.

These safety costs will have to be discounted to present values, as they will not only occur in the present (in the basic year, year 0), but throughout the remaining life span of the facility. Each of the different types of safety costs is explained in greater detail in the following sections.

Material Safety Costs

Maintenance of safety measures requires replacements for decrepit materials. The material costs of the replacement materials can be calculated by multiplying the price per unit of the materials by the units needed for the maintenance of the safety measure per year.

This calculation is represented by the following formula:

equation

where c05-math-0150 is the number of different materials.

These costs represent the maintenance material costs of one maintenance period, which is defined as one year. Thus if it is assumed that maintenance occurs on a yearly basis and the yearly cost is always the same, termed c05-math-0151, the total present value of all maintenance materials needed during the lifetime of the safety measure can be calculated by taking into account a discount factor, because the maintenance material costs occur throughout the remaining lifetime of the facility. The total present value is then given by the formula in the following box for annuities, as discussed in Section 5.2.4, (Eq. (5.4)).

Maintenance Team Safety Costs

The maintenance team safety costs are related to the maintenance activities of employees for the installed safety measure(s). These can be calculated and estimated by multiplying the hourly wage of such an employee by the number of hours the maintenance takes, and again by the number of employees participating. If employees with significantly varying wage levels are participating, the maintenance team costs can be calculated separately for each category of employees. Another possibility is to take the average wage level of all employees participating, and thus work with just one category.

This calculation is represented by the following formula:

equation

where c05-math-0167 is the number of employee categories.

These costs represent the maintenance team costs for one maintenance period, which is defined as 1 year. Thus, if we assume that maintenance occurs on a yearly basis and the yearly cost is always the same, termed c05-math-0168, the total present value of all maintenance teams needed during the lifetime of the safety measure can be calculated by taking into account a discount factor, because the maintenance team costs occur throughout the remaining lifetime of the facility. The total present value is given by the formula in the following box for annuities, as discussed in Section 5.2.4, (Eq. (5.4)).

Production Loss Safety Costs

When maintenance is periodically necessary for the optimal functioning of the safety measure, sometimes the production has to be stopped temporarily, resulting in a production loss. This production loss is accompanied by costs arising from the non-producing status of the facility. Production loss costs per maintenance period can be calculated by multiplying the production rate of the factory/refinery by the duration of the stop, and again by the profit per unit sold [7].

This calculation is represented by the following formula.

These safety costs represent the maintenance production loss safety costs of one maintenance period, which is defined as 1 year. Thus, if it is assumed that maintenance occurs on a yearly basis and the yearly cost is always the same, termed c05-math-0178, the total present value of all maintenance production loss during the lifetime of the safety measure can be calculated by taking into account a discount factor, because the maintenance production loss costs occur throughout the remaining lifetime of the facility. The total present value is given by the formula in the following box, (Eq. (5.4)).

Start-up Safety Costs (after Maintenance)

Maintenance of a new safety measure can cause a temporary slowdown in production due to the restart of the facility after halting production for necessary maintenance. The costs arising from the temporary slowdown in production are called start-up costs, and can be calculated by multiplying the difference in production rate before and after the halt in production by the duration from the time the production line is reactivated after the maintenance period of the safety measure to the time it returns to the initial production rate, and again by the profit per unit sold [7].

This calculation is represented by the following formula.

Notice that if the production rate at the time of the start-up is exactly the same as the rate before the halt in production, the start-up costs will be zero.

Also notice that the safety costs above represent the maintenance start-up safety costs of one maintenance period, which is defined as 1 year. Thus, if it is assumed that maintenance occurs on a yearly basis and the yearly cost is always the same, termed c05-math-0189, the total present value of all maintenance start-ups during the lifetime of the safety measure can be calculated by taking into account a discount factor, because the maintenance start-up costs occur throughout the remaining lifetime of the facility. The total present value is given by the formula in the following box, (Eq. (5.4)).

5.3.2.5 Inspection Safety Costs (Inspection Team Costs)

This cost will have to be discounted to a present value, as it will not only occur in the present (in the basic year, year 0), but throughout the remaining life span of the facility.

The inspection team safety costs are related to the periodic inspection and audit activities of the safety department of the company or an external auditing company, to check whether the safety measures are effective [8]. Carrying out periodic risk assessments can also be considered part of these safety costs. These inspection team costs can be calculated and estimated by multiplying the hourly wage of an employee by the number of hours the inspection takes, and again by the number of employees participating. If employees with significantly varying wage levels are involved, the inspection team safety costs can be calculated separately for each category of employees. Another possibility is to take the average wage level of all employees participating, and thus only work with one category.

This calculation is represented by the following formula:

equation

where c05-math-0205 is the number of employee categories.

These costs, however, represent the inspection team's safety costs for one inspection period, which is defined as 1 year. Thus if it is assumed that these costs occur on a yearly basis and the yearly cost is always the same, termed c05-math-0206, the total present value of all teams needed during the lifetime of the safety measure is calculated by considering a discount factor, because the inspection team costs occur throughout the remaining lifetime of the facility. The total present value is given by the formula in the following box, (Eq. (5.4)).

5.3.2.6 Logistics and Transport Safety Costs

Materials need to be transported and stored in a safe way. Control lists as well as safety documents need to be drawn up, filled in, and updated. The sub-categories of this cost category are as follows:

  1. 1. Transport and loading/unloading of hazardous materials safety costs
  2. 2. Storage of hazardous materials safety costs
  3. 3. Drafting control lists safety costs
  4. 4. Safety documents safety costs.
Transport and Loading/Unloading of Hazardous Materials

The transportation of materials and substances, such as the transport of gas cylinders, entails costs due to existing legislation and to extra measures for safety. Transport indeed requires compliance with existing regulations (e.g., ADR18) during transportation and during loading and unloading of goods, and sometimes extra safety measures are needed.

The transport costs of materials can be calculated by multiplying the transport price per material unit or good with the number of units or goods transported, for all materials that need to be transported.

equation

where

  1. c05-math-0212
  2. c05-math-0213
  3. c05-math-0214

These costs represent the transport safety costs of all materials transported during 1 year. Thus, if it is assumed that these costs occur on a yearly basis and the yearly cost is always the same, termed Ctransp, the total present value of all transport costs can be determined by the formula in the following box, (Eq. (5.4)).

Storage of Hazardous Materials Safety Costs

The storage costs can be determined by multiplying the storage price per material unit or good by the number of units or goods stored, for all materials that needs to be stored:

equation

where

  1. c05-math-0217
  2. c05-math-0218
  3. c05-math-0219

These costs represent the storage safety costs of all materials stored during 14 years. Thus, if it is assumed that these costs occur on a yearly basis and the yearly cost is always the same, termed Cstorage, the total present value of all storage costs can be determined by the formula in the following box.

Drafting Control Lists Safety Costs

It is necessary to draft control lists for transportation and storage [9]. The total cost of drafting such lists is obtained by multiplying the hourly wage of persons responsible for the drafting by the number of hours needed to draft the lists per category of person, and summing all categories and persons. This cost only needs to be considered once, as once the lists have been drafted, they can be reused afterwards.

This calculation is represented by the following formula:

equation

where t is the number of employee categories.

Safety Documents Safety Costs

Safety documents periodically need to be filled in by employee(s) [9]. The cost arising from the filling in of safety documents can be determined by multiplying the hourly wage of those employees by the number of hours needed to fill in the documents and again by the number of employees participating. If employees with significantly varying wage levels participate, the safety documents safety costs can be calculated separately for each category of employees. Another possibility is to take the average wage level of all employees participating, and thus work with just one category.

This calculation is represented by the following formula:

equation

where t = number of employee categories.

These costs represent the safety document safety costs of one period, which is defined as, say, 1 year. Thus, if it is assumed that these costs occur on a yearly basis and the yearly cost is always the same, termed CSD, the total present value of all teams needed during the filling in of safety documents is calculated by considering a discount factor, because the safety document costs occur yearly for the remaining lifetime of the facility under consideration. The total present value is given by the formula in the following box.

5.3.2.7 Contractor Safety Costs

If a company works with contractors, they need to be selected, taking safety into account. The selection process, as well as the contractor training aimed at company safety, represents a safety cost. Moreover, a loss of working time as a result of training the contractors should also be considered. Therefore, contractor safety costs include:

  1. 1. Contractor selection safety costs
  2. 2. Training safety costs.
Contractor Selection Safety Costs

Contractor firms need to be chosen with “safety” as one of the most important selection parameters. The selection is conducted by employees of the company, and the costs can thus be determined by taking these employee costs into consideration.

This calculation is represented by the following formula:

equation

where t is the number of employee categories.

These costs represent the contractor selection safety costs for one period, which is defined as, say, 1 year. Thus, if it is assumed that these costs occur on a yearly basis and the yearly cost is always the same, termed CSel, the total present value of all contractor selection procedures is calculated by considering a discount factor, because the contractor selection costs may occur yearly for the remaining lifetime of the facility under consideration. If the contractor selection costs only need to be incurred once, there is evidently no need to use a discount factor and calculate a NPV. If another time period is used for the selection, e.g., a 5-year period, the formula needs to be adjusted for this. The total present value for a 1-year period is given by the formula in the following box.

Contractor Training Safety Costs

Contractor employees, when selected by a company, often need to receive safety training within the company, as well as receiving instructions and guidelines for working at or with certain installations. These extra costs, which are related to safety, should also be taken into consideration.

This calculation is represented by the following formula:

equation

where t is the number of employee categories.

These costs represent the training safety costs of one period, which is defined as, say, 1 year. Thus, if it is assumed that these costs occur on a yearly basis and the yearly cost is always the same, termed CST, the total present value of all safety training needs is calculated by considering a discount factor, because the safety document costs occur yearly for the remaining lifetime of the facility under consideration. The total present value is given by the formula in the following box.

5.3.2.8 Other Safety Costs

Safety costs that cannot be assigned to one of the categories already discussed in the previous sections are listed under “other safety costs” and can/should be mentioned in this category.

5.4 Calculating Benefits (Avoided Accident Costs)

The purpose of implementing safety measures is to reduce present and future risks. By “reducing the risk,” the prevention of accidents is indicated, as well as the mitigation of the consequences of an accident should it occur after all. Thus, the benefits of a safety investment/measure can be regarded as the difference in consequences without and with a safety investment/measure, taking into account the difference in likelihood of an accident occurring. The “consequences without safety measure” can be seen as the potential (hypothetical) consequences of accident scenarios. The “consequences with safety measure” are those consequences that are still possible after taking a specific safety measure for the accident scenario. In this section, the various financial aspects of consequences related to an accident (scenario) will be discussed, as well as the formulas for calculating these aspects.

5.4.1 Distinction between Various Accident Costs

The literature mentions a number of accident cost categories and taxonomies, the most used and well-known accident cost categories being direct and indirect costs, and insured and uninsured costs.

5.4.1.1 Direct and Indirect Accident Costs

Direct accident costs represent costs that are immediately visible and tangible. They can be seen as “logical, common-sense consequences of the accident.” Conversely, indirect costs are those accident costs that are difficult to assess, and they are often intangible and invisible.

The costs of accidents are often much higher than merely the sum of the direct and visible costs. In fact, indirect costs usually represent a multiple of the direct costs and they are therefore a very important factor when analyzing accidents and making decisions on safety investments for dealing with both type I and type II risks. A number of researchers have tried to draft ratios of direct over indirect costs, and a variety of ratios can be found in the literature, depending on the nature of the study (e.g., depending on the industrial sector in which the research was conducted). A well-known and much used ratio for type I accident costs is that of Heinrich, the father of industrial safety discussed in Sections 1.1. Based on a study of 75 000 type I accidents, Heinrich [10] concluded that indirect costs are four times higher than direct costs. But, as already mentioned, other studies have found different ratios.

Gavious et al. [7], for example, define the total cost of an accident as the sum of the direct costs, the indirect costs, the so-called payment costs and the immeasurable costs. In this taxonomy, the direct costs imply all costs due to installation damages, product losses, and equipment detriment. Medical costs, fines and insurance costs are considered to be direct costs by these authors. Indirect costs are caused by production delays and/or halts. Due to production problems and halts, delivery to clients could be problematic and contractual costs could result, as well as having to pay third parties, and so on. Payment costs include having to pay employees despite them being at home due to injury. The immeasurable costs result from reputation decrease and moral or psychological damage to employees, possibly leading to lower quality of life and lower productivity. An overview of the taxonomy of accident costs as proposed by Gavious et al. [7] can be found in Table 5.4.

Table 5.4 Taxonomy of accident costs

Direct costs Damage Damage to installations, products and equipment
Medical Evacuation to hospital, used materials for first aid, hospitalization
Juridical Paying fines
Insurance Insurance premium rise
Indirect costs Capacity losses Production delays/stops, production decrease and problems
Production scheme Planning problems with clients and suppliers
Recruitment Costs of replacement of employees
Wage costs Costs of employees carrying out the accident investigation
Payment costs Wage costs Wage costs of injured employees being at home
Immeasurable costs Moral damages
Reputation decrease

Gavious et al. [7]. Reproduced with permission from Elsevier.

5.4.1.2 Insured and Uninsured Accident Costs

The division of accident costs into insured and uninsured costs was conceptualized by Simmonds [11]. The insured costs comprise employees' wages, insured medical expenses and damage to property. Uninsured costs are composed of uninsured medical costs, wage costs due to lower output of employees upon return, cost of education or training of new employees, and so on. It should be noted that the categorization of insured and uninsured costs depends on the type of accident and the insurance premium. An illustrative scheme of a possible taxonomy is provided by Sun et al. [12] (see Figure 5.2).

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Figure 5.2 Insured and uninsured costs.

(Source: Sun et al. [12]. Reproduced with permission from Taylor & Francis.)

A distinction needs to be made between avoided type I accident costs and avoided type II accident costs. Some costs may apply in both cases, i.e., in both type I and type II accidents, but others might only apply to one type of accident. The next section therefore discusses all kinds of avoided costs (in other words, benefits), but clearly highlights which types of accident the avoided accident costs are applicable to.

5.4.2 Avoided Accident Costs

For each of the avoided accident cost categories mentioned in Table 5.5, formulas were developed that can be used in a CBA and/or a cost-effectiveness analysis exercise or tool in order to calculate the benefits linked to type I and type II risks. The table highlights what types of risk the formulas can be used for. If there are no accurate variables available for use in some of the subcategories, information derived from previously executed projects within the company can be used; another option is to use estimated consequences from an independent partner company. If needed, this information can then eventually be used to determine one or more flat-rate amounts representing one or more of the avoided cost subcategories in Table 5.5.

Table 5.5 Avoided accident cost categories

Type of avoided accident cost Subcategory of avoided accident cost
Supply chain (Section 5.4.2.1) Production-related (type I + type II)
Start-up (type I + type II)
Schedule-related (type I + type II)
Damage (Section 5.4.2.2) Damage to own material/property (type I + type II)
Damage to other companies' material/property (type II)
Damage to surrounding living areas (type II)
Damage to public material property (type II)
Legal (Section 5.4.2.3) Fines (type I + type II)
Interim lawyers (type II)
Specialized lawyers (type II)
Internal research team (type II)
Experts at hearings (type II)
Legislation (type II)
Permit and license (type II)
Insurance (Section 5.4.2.4) Insurance premium (type I + type II)
Human and environmental (Section 5.4.2.5) Compensation victims (type I + type II)
Injured employees (type I + type II)
Recruitment (type I + type II)
Environmental damage (type I + type II)
Personnel (Section 5.4.2.6) Productivity of personnel (type I + type II)
Training of new or temporary employees (type I + type II)
Wages (type I + type II)
Medical (Section 5.4.2.7) Medical treatment at location (type I + type II)
Medical treatment in hospitals and revalidation (type I + type II)
Using medical equipment and devices (type I + type II)
Medical transport (type I + type II)
Intervention (Section 5.4.2.8) Intervention (type I + type II)
Reputation (Section 5.4.2.9) Share price (type II)
Other (Section 5.4.2.10) Accident investigation (type I + type II)
Manager working time (type I + type II)
Clean-up (type I + type II)

As the consequences of an accident only become a reality when the accident actually occurs, the probability of occurrence should be taken into account in the calculation of the expected hypothetical benefits in some way. Therefore the consequences, calculated using either the appropriate formula or a flat-rate amount, will have to be multiplied by the probability of occurrence in order to obtain the expected hypothetical benefits due to an accident scenario. Thus, if the different kinds of hypothetical consequences are considered to be spread out on a yearly basis, and the yearly cost arising from these consequences is considered to be always the same, Ci = C for all i, then the total present value of all hypothetical costs of an accident scenario during the remaining lifetime of the facility can be calculated by taking into account both the remaining lifetime and a discount factor. The total present value of each of the consequence subcategories is given by the formula for annuities, as discussed in Section 5.2.4.

This calculation has to be executed for the cases both with and without the implementation of the safety measure. The difference between the two present values of consequence costs represents the maxmax hypothetical benefit (see also Section 4.2.4) resulting from the implementation of the new safety investment:

equation

This calculation is identical for all of the consequences discussed in the following sections.

If the probabilities of accident scenarios are used, the expected hypothetical benefits can be determined. Indeed, the value that is generated by the various formulas explained further in this section needs to be multiplied by the frequency of occurrence or the probability of the event, in order to obtain the expected annual avoided costs. Afterwards, this annual avoided cost is used in the formula for annuities in order to obtain the present value of the consequences for the remaining lifetime of the facility. This needs to be carried out for both the situations without and with the new safety measure, and the difference between the two present values represents the expected hypothetical benefit with regard to that specific subcategory. This calculation is identical for all defined subcategories of consequences and has to be carried out for every one of them.

5.4.2.1 Supply Chain Avoided Costs

Production-related Avoided Costs (Type I + Type II)

When an accident occurs, it is possible that (a part of) the production will be halted, resulting in a production loss. This production loss is accompanied by costs because of the non-producing status of (a part of) the factory or plant. Production loss costs can be calculated by multiplying the production capacity/rate of the facility by the estimated duration of the halt, and again by the profit per unit sold [7].

This calculation is represented by the following formula.

Start-up Avoided Costs (Type I + Type II)

When the production is re-started after an accident, a temporary slowdown in production due to the restart of the facility can occur. The costs accompanied by the temporary slowdown in production are called start-up costs, and these can be calculated by multiplying the difference in the production rate before and after the halt in production by the duration from the time the production line is reactivated after the accident occurred to the time when the production line returns to the initial production rate, and again by the profit per unit sold [7].

This calculation is represented by the following formula.

Note that if the production rate at the time of the start-up is exactly the same as the that before the halt in production, the start-up costs will be zero.

Schedule-related Avoided Costs (Type I + Type II)

If an accident occurs, this will also affect the production timetable of the factory, which can cause problems with clients. The possibility exists that clients may cancel one or more contracts, or may demand a lower price due to the delay. One solution may be to hire a contractor who can help the company to provide the necessary products to meet the company's time schedule. However, a scheduling problem will not only affect clients and customers, but also partners and suppliers. If the company produces part of a product and a partner company finishes the partly completed product, the partner company will also face supply chain costs, as the company will have to wait longer for the partly completed products to arrive. In the case of suppliers, the problem is that, if the company cannot produce, its inventory stays the same. Because of the latter the company will not need fresh suppliers at the normal rate, and thus the agreements with suppliers will have to be changed/canceled, which will also cause the suppliers some scheduling problems.

The costs arising from these scheduling problems can be arrived at by adding up three aspects. The first is obtained by multiplying the fine for a canceled order/contract by the number of canceled orders/contracts. The second is obtained by multiplying the fine due to delays in deliveries per day by the number of days the orders are late, and again by the number of orders that have a delay. Finally, the third cost is calculated by multiplying the number of units supplied by the contractor, by the difference between the cost per unit charged by the contractor and the in-house cost per unit [7].

This calculation is represented by the following formula.

5.4.2.2 Damage Avoided Costs

Avoided Costs with Respect to Damage to Own Material/Property (Type I + Type II)

An accident may lead to damage to buildings, infrastructure, products, machines, and so on. These costs are labeled as “damage costs” and are usually taken into account in any CBA.

These avoided costs are represented by the following formula.

Avoided Costs with Respect to Damage to Other Companies' Material/Property (Type II)

An type II accident might cause damage to other companies' material and property, in addition to damage to the company's own assets. The company needs to pay for the damage incurred by other companies, as they will probably file claims against the company that caused the damage [8]. These costs are also labeled as damage costs, and should be taken into account in an economic analysis.

These avoided costs are represented by the following formula.

Avoided Costs with Respect to Damage to Surrounding Living Areas (Type II)

An type II accident sometimes causes damage to residential properties. The company will have to pay for this damage, as the inhabitants are likely to file claims against the company that caused the accident. These costs are also labeled as damage costs and should be taken into account in the CBA. For example, in the case of the major accident that occurred in Buncefield in Hertfordshire, UK, in 2005, there was widespread damage to both commercial and residential properties near the site. Some properties close to the depot were destroyed, while others suffered damage. As a consequence, about 2000 people had to be evacuated from their homes, some for long periods of time. In addition, properties as far as 8 km away from the Buncefield site suffered minor damage, such as broken windows [13].

Another example is the Deepwater Horizon disaster that took place in the Gulf of Mexico in 2010. The consequences to the flora and fauna in the Gulf of Mexico and along the Louisiana coastline were truly disastrous and, as a result, the local fishermen's economy simply ceased to exist for a certain period, which led to huge compensation claims.

Such avoided costs can be represented by the following formula.

Avoided Costs with Respect to Damage to Public Material/Property (Type II)

In some cases, a type II accident will cause damage to public material and property. The company needs to pay for that damage as well, as the local government will probably file claims against the company that caused the accident [8]. These costs are also labeled as damage costs.

These avoided costs are represented by the following formula.

5.4.2.3 Legal Consequences Avoided Costs

The different types of legal consequences of an accident are explained in greater detail in this section. The legal aspects turn out to be an important part of the hypothetical benefits, especially in the case of type II risks. One can imagine that whenever an accident occurs, especially a major one, the legal department of a company will be placed under a lot of stress. In the case of a type II accident, a lot of financial resources will have to be spent to handle that pressure by hiring additional staff members and experts to deal with the complexity of such an accident. In addition, the legal environment in which the company operates will change according to the occurrence of catastrophes, and the company will need to make sure that it complies with these changes.

Fines-related Avoided Costs (Type I + Type II)

If an accident occurs, the government and other organizations will try to identify responsible individuals or a responsible group of individuals. In some cases the company as a whole will be held responsible for the accident, while in other cases employees, managers or other persons may be held responsible [14].

Responsible persons or the responsible organization may be exposed to civil liability, administrative liability and/or criminal liability for the major accident. Having both administrative and criminal liability carries with it the obligation of paying fines. The difference between the two types of liability is explained here. Criminal liability arises when someone or some organization has hurt or killed people, or the property has been destroyed on purpose, whereas administrative liability comes into play when one has not operated and behaved according to the law and to prescribed procedures and methods. Thus, if an accident is caused due to violations of safety procedures and/or through breaking the law, the organization may be exposed to fines and claims by the authorities due to the administrative liability [7, 14]. Another difference lies in the importance and weight of the sentence, which are significantly different. On top of the fine, criminal liability will result in a criminal record and there may be serious punishment as a consequence, such as a custodial sentence. This is not the case with administrative liability, which only results in a fine.

Consider, as an example, the major accident that took place at Total's ammonium nitrate warehouse in the AZF fertilizer factory in an industrial zone in Toulouse, France. As a result of this accident, 30 people were killed and about 3000 were injured. Serge Biechlin, the former CEO of the Total subsidiary, Grande Paroisse, received a criminal liability fine of US $58 000 and was sentenced to 1 year in prison. The court decided on a 3-year jail term, 2 years suspended, and a US $58 000 fine for manslaughter. Grande Paroisse also received a criminal liability fine of €225 000, which is the maximum amount possible. The court ruled that Biechlin had contributed to creating the situation that resulted in the damage and did not take steps to avoid it, and had also exposed employees and the surrounding population to a serious risk [15].

However, these fines are usually negligible compared to the compensation one has to pay for being exposed to civil liability after a major accident. Civil liability means compensating for every form of damage that arises as a consequence of the major accident. Thus the responsible party has to compensate for lost lives, injured people, materials, buildings, and so on [14]. In the case of the major accident at AZF, as a result of civil liability, Grande Paroisse has paid out more than €2 billion (US $2.7 billion) in compensation to more than 16 000 victims, according to Total's figures [15].

In former times, governments and other organizations always held individuals responsible for major accidents, and they therefore paid the price for having the criminal, administrative, and civil liability. They did this because organizations and companies could not be held liable for major accidents. This has now changed, and companies can be sentenced and forced to pay fines. Because companies cannot go to jail, managers and other employees are still being pursued over fines and possible jail time [14].

Another example of managers of industrial facilities being held responsible for a major accident is the case of the 1984 gas disaster at Union Carbide's pesticide plant in Bhopal, India. Even 30 years after the accident, India was still pushing the US to extradite Warren Anderson, the former boss of the facility. Right up until he died in 2014, he faced charges of criminal negligence, and thus probably would have been sentenced to prison if the US had agreed to send him to India. Anderson was initially arrested in India after the catastrophe, but then managed to flee the country. From 1984, the US authorities turned down frequent extradition requests for Anderson. Seven local managers who were working at the Union Carbide plant in 1984 were convicted [16].

These avoided costs are represented by the following formula.

Interim Lawyers Avoided Costs (Type II)

If a major accident occurs, the government will assemble a research team to discover what caused the accident and what the consequences are for the country, society, and environment. A company lawyer will also be assigned to help carry out this research and this person will therefore be unavailable in his or her usual company role. Therefore the company will need to hire an interim lawyer for the full duration of the research.

The costs related to the hiring of interim lawyers due to the occurrence of a major accident can be calculated and estimated by multiplying the daily wage of such a lawyer by the number of days he or she will be hired, and again by the number of lawyers that the company wishes to hire. If, however, the company decides to hire both junior and senior interim lawyers, the user may want to calculate the costs separately for both categories of lawyers.

These avoided costs are represented by the following formula.

Specialized Lawyers Avoided Costs (Type II)

In the event of a trial regarding major accidents, companies will hire lawyers who are specialized in these types of disaster. These lawyers will require substantial salaries and are expensive for any organization, even for a large multinational, as trials surrounding major accidents can take several years. However, the costs of specialized lawyers vary widely depending on the country in which the accident occurs or where the trial takes place. Often a deal is made between the two parties or a flat-rate amount is used. In any case, trials and lawsuits surrounding major accidents that take several years can easily cost the company hiring specialized lawyers several millions of euros [14].

The costs related to the hiring of specialized lawyers after a major accident can be calculated and estimated by multiplying the hourly wage of such a lawyer by the number of hours he/she will be hired, and again by the number of lawyers that the company wishes to hire. If, however, the company decides to hire specialized lawyers with widely varying wage levels, the user may want to calculate the avoided costs separately for those categories of lawyers.

This calculation is represented by the following formula:

equation

where t is the number of lawyer categories

Internal Research Team Avoided Costs (Type II)

Independent of the research team assembled by the government and of any investigation carried out by other organizations involved in the major accident, a research team will always also be assembled by the company itself. This research team will mainly consist of health and safety experts and other specialists, and its purpose is to analyze the available information to identify the possible causes of the accident and make recommendations aimed at preventing similar accidents in the company's plants in future [14, 17].

An example of such a team is BP's investigation team after the Deepwater Horizon accident. The team began its work immediately in the aftermath of the incident, working independently of other accident response activities and organizations. When the investigation was being conducted, numerous similar investigations were ongoing. These included investigations by the US Coast Guard, the Bureau of Energy Management, the Regulation and Enforcement Joint Investigation, Transocean, the President of the United States' National Commission, and the Norwegian Institute for Water Research. More than 50 specialists, both internal and external, participated in the investigation of BP itself. The people involved were specialists in safety, drilling, exploration, well control, subsea engineering, and many more related fields. The outcomes of the research done by the government and the company will serve as evidence in determining the liable party [14, 17].

The costs related to the internal team investigating a major accident can be calculated and estimated by multiplying the daily wage of people participating by the number of days they will be hired, and again by the number of people the company wishes to assemble. If employees with significantly varying wage levels participate, the user may want to calculate the internal investigation team costs separately. Another possibility is to take the average wage level of all employees participating, meaning the user of the tool will only have to work with one category.

This calculation is represented by the following formula:

equation

where t is the number of employee categories

Experts at Hearings Avoided Costs (Type II)

In addition, experts in their field will sometimes be invited to testify and state their opinion in court. The party that is held accountable for a type II accident will pay the salary of these experts. The company will also have the possibility of hiring additional experts, to challenge the findings of the initial experts.

The costs related to the hiring of experts due to the occurrence of a major accident can be calculated and estimated by multiplying the hourly wage of experts participating by the number of hours they will be hired, and again by the number of experts that the company wishes to hire. If experts with significantly varying wage levels participate, the user may want to calculate the experts' costs separately. Another possibility is to take the average wage level of all experts participating, meaning the user of the tool will only have to work with one category.

This calculation is represented by the following formula:

equation

where t is the number of expert categories

Avoided Costs Related to Legislation Changes (Type II)

Companies all over the world have invested resources in the field of safety as a response to legislation and directives. For instance, in Europe the major industrial accident prevention legislation is called the Seveso Directive, the first version of which was issued in 1982 as a result of the major accident that occurred in Seveso, Italy, 6 years earlier, in 1976. Vierendeels et al. [18] indicate that there are two drivers for legislation changes: (i) scientific progress and societal changes; and (ii) a shock effect (i.e., major accidents). However, the exact relationship between the occurrence of a major accident and a change in legislation is not unambiguous, and this relationship is discussed here. First, the history of major risk regulation is explained, and the connection between the occurrence of major accidents and legislation is clearly underlined.

At the beginning of the nineteenth century, more specifically the year 1810, the first regulation regarding major risks was born, as a result of an accident in 1794 in Grenelle, France, in which about 1000 people died. Over the following decades, similar catastrophes occurred in Europe, triggering the enactment of similar legislation regarding major industrial risks. In 1982 the first European Directive concerning major risks, Seveso I, was issued as a response to major accidents in Flixborough in the UK (in 1974) and Seveso in Italy (in 1976). The legislation has been changed several times since then, mainly because of subsequent major industrial accidents. For example, the accident that occurred at Bhopal in India in 1984 and the Rhine pollution at Basel in Switzerland in 1986 resulted directly in new amendments in 1987 and 1988. Together with major accidents in Mexico City in 1984 and on the Piper Alpha oil rig in 1987, these accidents resulted in changes in legislation, and in 1996 the Seveso II Directive was approved. However, major accidents continued to happen and mainly because of the shock effects, such as caused by the accidents in Baia Mare in Romania in 2000, Enschede in the Netherlands in the same year, and Toulouse in France in 2001, the legislation was changed and amended again in 2003. On June 1, 2015, a new version of the legislation for major risks, the Seveso III Directive, entered into force in Europe. It is clear, then, that legislation is subject to frequent changes as new accidents and new challenges arise. This is a time-consuming and costly process not only for governments, but also for private companies, as they have to analyze and implement the altered regulations in order to comply [18].

There is, therefore, clearly a correlation between the occurrence of major accidents and legislation changes, and, as already indicated, it is a result of the so-called shock effect. An accident can have a shock effect on regulation if the consequences are severe enough. A study by Vierendeels et al. [18] indicates that an accident causing 20 casualties, or even, in some cases, eight to 10 casualties, can have such a shock effect. The difference in the number of victims that can produce such an effect is explained by the fact that the media and the public, and thus also the politicians, often perceive an event as less significant if the casualties are employees or rescue workers, and more significant if they are civilians from the surrounding community. The number of fatalities, however, is not the only cause of a significant shock effect that can lead to a change in regulation. Others include, for example, a visible and traceable disposal of chemical substances in air, water, or soil that could have long-term health effects as well as the cost of an accident. If the accident costs exceed €1 billion, it is highly probable that the resulting shock effect will be large enough to bring about a change in legislation, even if there are no casualties involved [18].

Future changes in major accident legislation will be accompanied by a large financial, administrative, and operational burden. However, costs related to legislation changes as a result of a major accident are difficult to quantify directly. Nonetheless, they can be calculated indirectly by multiplying the total safety budget of the type of facility under consideration by the estimated increase (in %) of the safety budget (due to the occurrence of an accident scenario that will cause the legislation to change and become more complex).

These costs are represented by the following formula.

Permits and Licenses Avoided Costs (Type II)

It will become harder for a company to obtain the necessary exploitation permits and operating licenses in the country where a major accident involving the company might occur. In general, companies (e.g., those with activities in the fields of petrochemicals, energy, and chemicals) need to be rigorous in obeying the rules for obtaining permits and licenses. They cannot afford to lose operating and exploitation permits through reckless behavior, as this could be a financial disaster for the company. For instance, if a company has had a relatively large number of minor accidents and is close to not obtaining a renewal of its permits and licenses, a major accident might well mean the end of their operating permit.

The costs related to obtaining new permits and licenses due to the occurrence of a major accident are difficult to quantify. However, they can be estimated by multiplying the total costs of having to close down the facility by the likelihood that the company will lose its operating permit due to a major accident.

These avoided costs are represented by the following formula.

Lawsuits Avoided Costs (Type II)

The costs accompanying lawsuits and trials can become substantial and can pose a significant threat to the liquidity of the company. This is primarily caused by the fact that such lawsuits and trials can last a number of years, sometimes more than a decade. Thus, it would be in the best interests of any company to avoid such time- and money-consuming trials. But how can this be achieved? One possible solution is by acting in a proactive way, as Fina did in 1995 after the explosion in Eynatten, Belgium. On the June 18, 1995 an explosion destroyed the Fina-owned road restaurant and gas station next to the E40 highway. This explosion was caused by a gas leak in the kitchen of the restaurant, and it killed 16 people and injured 20 more who had to be transported by helicopter to a hospital in Aken, Germany [19, 20]. Immediately after the explosion, the emergency procedure was set in motion. During this procedure, a helicopter, the police, the fire department of three nearby villages, the Red Cross, and the civil protection unit were present at the explosion site. In total, between 100 and 150 people were present [21]. Instead of acting in the traditional way, whereby a company waits to compensate the victims until it is clear who is liable and responsible for the accident, Fina took the initiative and compensated the injured and the families of the victims straight away. It would become clear later on after investigation which company was liable and thus responsible for the explosion, and once that decision was taken, the compensation that Fina had already paid could be recouped from their insurance company or the insurance company of the responsible party. The most important fact for Fina at that moment was that the people who suffered from this accident received compensation immediately. By acting in this proactive way, Fina possibly reduced the amount of expensive lawsuits and trials and therefore the number of lawyers required. None of the victims sued Fina for injuries or deaths. This approach also reduced the number of times that Fina appeared in the media in a negative way, as they surely would have through numerous trials and continued denial of their responsibility. In addition, this further reduced the negative impact of the explosion on Fina's image and reputation, as they had sent a clear message to the world by compensating other parties immediately, proving that their company takes full responsibility and that they care about others [14].

As noted, the reduction in the number of trials would have had a positive effect on the image and reputation of the company, in turn possibly having a positive effect on its sales, which might have been reduced as a result of the negative media attention. In turn, by acting proactively, the company took care of a possible market-value decrease, represented by a decrease in its share price on the stock market. Companies operating in certain areas, such as, for example, the chemical, oil, and gas industries, should always remember that it takes years to build a good image. By contrast, a good reputation can be destroyed in just one brief moment, which it will take several years to rebuild.

It should be noted that insurance companies will usually not let the company act in such a proactive way (i.e., compensating losses before the court decision), as they will want to keep the amount spent in the aftermath of an accident as low as possible, because they will have to bear the majority of those costs. Instead of taking into account the reduction of the legal costs, they will be more concerned with the possibility that the other party will ask for more money as compensation than they deserve. However, this turns out to be negligible compared with the major legal costs and indirect costs resulting from reputational risk to their client in the case of a major (type II) accident.

5.4.2.4 Insurance Avoided Costs (Type I + Type II)

In order to understand insurance premium increases, insurances as a whole are discussed briefly before discussing the premium. Consider the following definitions of insurance [22]:

  • The pooling of fortuitous losses by transfer of the risks to insurers, who agree to indemnify insured parties for such losses, to provide other pecuniary benefits on their occurrence or to render services connected with the risk. Pooling is the sharing of total losses among a group and is thus the spreading of losses incurred by a few over an entire group.
  • A system to protect persons, groups, or businesses against certain risks of financial loss by transferring the risks to a large group who agree to share the financial losses in exchange for premium payments.
  • A written contract between two parties providing a promise of reimbursement in the case of loss; purchased by people or companies so concerned about hazards that they have made prepayments to an insurance company for such risk treatment.

In summary, insurances arrange the transferring of risks and the sharing of losses. It is always a contract between two parties, the insured party and the insurance company. Table 5.6 lists some important characteristics about insurances. These features are vital to understand how insurances work and how they affect the financial position of a company.

Table 5.6 Insurance characteristics

What do insurances actually do?
  • Insurance aims at restoring/indemnifying/compensating the insured should the risk translate into an incident.
  • It does not put the insured in a better position than they were before the loss (that would invite fraud).
  • It is based on probabilities – the incident(s) may or may not occur.
What are insurances not?
  • The total solution.
  • A guarantee that an incident will not occur.
  • A guarantee that all costs of damages will be repaid.
  • A protection against reputation and market losses or image destruction.
  • An alternative for risk management.
Why does a company need insurances?
  • Because operational risk management cannot eliminate all operational risks.
  • Because it is an acceptable choice to transfer operational risk (as one possible risk treatment option).
  • Because bad luck does exist.
  • To receive financial compensation from a third party for losses companies perhaps cannot bear themselves.
  • Because it contributes to a stable working environment.
  • Because it may be a regulatory or contractual requirement.
  • Because through insurances the long-term future of the company will not be compromised.

Depré [22].

Insurances need an individual approach; they are different according to insurer, facility, and country. Therefore no insurance in any industry is exactly the same. There are all kinds of insurances, such as business interruption insurances and property damage insurances, which all assist the company with the financial burden it would face were an accident to occur. For example, in the process industry, the most important insurances are [23]:

  • Property and physical damage
  • Machinery breakdown
  • Business interruption
  • Liability: public liability, product liability, recall
  • Employers' liability (for accidents in which employees are injured or killed)
  • Environmental insurances: own premises and third liability
  • Transport (marine cargo/goods in transit/storage risks)
  • Project insurances
  • D&O (directors' and officers') insurances.

By paying a yearly insurance premium, companies aim to ensure that the insurance company will take responsibility for (part of) the financial burden if an accident would occur. Many minor accidents or some major accidents will affect the insurance premium that a company has to pay. In order to understand how this premium will change, companies should first understand how premiums are calculated. An insurance company takes into account both the value of the assets that need to be insured and the accidents and damage that have occurred in the past. Because these data are from the past, insurance companies extrapolate them to the future to arrive at the required insurance premium. The premium also depends on the size of a company (e.g., a multinational or a national company), and on the geographical locations of it plants. In addition, the insurance company will add a profit margin to the insurance premium.

In the specific case of type II accidents, one problem is that there is too little information available, what makes it very difficult, if not impossible, to accurately extrapolate into the future. In addition, the intrinsic value of the assets to be insured is very large in some cases (e.g., in the process industry). This results in insurance premiums being very high. The combination of the lack of data and magnitude of insurance premiums means that premiums are usually determined during negotiations between the company and an insurance broker, representing the insurance company. Therefore, there is no formula or rule of thumb for determining the premium increase after a major accident, as this will be discussed during negotiations between the company and the insurance broker. However, because (among other things) all accidents and damage that occurred in the past are taken into account in the calculation of the premium, we know that the premium will definitely increase after the occurrence of a major accident. Notice that in case of a number of minor accidents, it is much easier to determine the rise of the insurance premium, as a lot more information is available in these cases.

In the case of type II major accidents, there is an additional factor that can influence the insurance premium. This additional factor is the reinsurance company, which reinsures the insurance company. If, for example, there have been a larger than expected number of major industrial accidents, the reinsurance company will have a hard time dealing with those claims, resulting in more difficult negotiations between the reinsurance and insurance companies. This, in turn, results in more difficult negotiations between the insurance company and the companies where the major accidents occurred, resulting in larger premium increases [24].

This all means that it is very difficult to predict by what percentage the insurance premium will increase after a number of minor or major accidents, but the insurance broker or people working in the company's insurance department will estimate this percentage increase by looking at the magnitude of the consequences predicted by the health and safety department. Although the insurance premium consequences are hard to predict, they are calculated by multiplying the current total insurance premium cost of the facility by the expected increase in the premium.

The insurance premium avoided costs can thus be represented by the following formula.

5.4.2.5 Human and Environmental Avoided Costs

Compensation Victims Avoided Costs (Type I + Type II)

Whenever an accident causes casualties, the company will have to compensate the families for their losses [8]. These costs are also labeled as compensation victims costs, and should be taken into account in any CBA. These consequences can be calculated by multiplying the VoSL in the specific country or region (see Chapter 4 for a discussion on calculating the VoSL considering the probability of the accident scenario) by the expected number of fatalities.

These costs are then represented by the following formula.

Injured Employees Avoided Costs (Type I + Type II)

Whenever an accident causes injuries, both minor and major injuries, the company will have to compensate the injured people for their injuries [8]. These consequences are calculated by multiplying the cost of lightly and seriously injured workers in that specific region by the expected number of lightly and heavily injured people.

These avoided costs are represented by the following formula.

Avoided Recruitment Costs (Type I + Type II)

As some employees may be injured or killed or leave the company due to an accident, new employees will have to be recruited. The recruiting cost is thus the cost of hiring new workers, which includes the time invested in recruiting and training the new workers. The recruitment consequences are calculated by multiplying the sum of the hiring and training costs by the number of newly recruited employees. Hiring costs include advertising, interviews and assessments, and other costs [7].

These avoided costs are represented by the following formula.

These avoided costs are represented by the following formula:

equation

where t is the number of employee categories.

Avoided Costs with Respect to Environmental Damage (Type I + Type II)

Whenever an accident causes environmental damage, the company will receive claims to compensate for the damage. These consequences are calculated by multiplying the mass of the spill by the expected cost per mass unit spilled.

These avoided costs are represented by the following formula.

5.4.2.6 Personnel-related Avoided Costs

Accidents often result in situations where employees are temporarily unable to carry out their job and daily activities, for short or long periods of time, or sometimes even indefinitely. Alternatively, employees may be obliged to perform activities other than the ones they are used to. Such situations entail avoided accident costs related to personnel and their productivity.

Lowered/Lost Productivity Avoided Costs (Type I + Type II)

Productivity of employees often decreases due to an incident or accident. This productivity loss is not merely the result of the employee who is actively involved in the accident, but can also result from other employees displaying lower productivity patterns. Furthermore, irrespective of the fact that due to an accident an employee can be incapable to work for a certain period of time, when that person returns to work he or she often displays lower productivity. It is sometimes possible that physical problems and restrictions and/or an altered risk perception (the so-called Hawthorne effect, cf. [12, 25]) can lead to different behaviors resulting in lower productivity. If “adapted work” is foreseen for the employee, productivity will most likely be lower as well. If the employee needs to be replaced, productivity levels will also be lower, especially initially, owing to a lack of experience and expertise [11, 26].

Formulas to deal with lost productivity are as follows

and

Training of Temporary Workforce Avoided Costs

Training people who are to replace those employees who suffered an accident also represents a cost. The most important part of this cost is time. The time needed by the trainer having to train the person who replaces the injured employee, as well as the training time of the substitute, needs to be counted. The latter can also be seen as lowered productivity, as, during the training period, the substitute does not attain his/her optimal productivity [11, 26, 27].

Wage Avoided Costs

Accidents always go hand in hand with a lot of loss of time. The “wage cost” represents the amount of time that company employees cannot devote to their regular tasks as a result of an accident. This may be the result of necessary medical treatment at the company's first aid department, in which case the corresponding wage cost may be negligible. However, when the accident leads to a longer period of lost work, the wage cost can be significant [7, 11, 25, 26, 28]. There may also be a wage cost due to employee colleagues having to work extra hours in the event of an accident.

5.4.2.7 Medical-related Avoided Costs

This category of avoided costs only applies to accidents involving one or more injured persons. Medical expenses are often an important part of the total cost of an accident, but they are mostly considered as insured costs. The degree to which such costs are, in fact, insured depends on the insurance policy.

Medical Treatment at Location Avoided Costs (Type I + Type II)

Large companies usually have their own medical service department, so that in the case of occupational accidents, medical personnel of the organization may offer first aid. Sometimes, it is necessary for the medical service to travel to the site of an accident, leading to a possible cost. It should be noted that due to legislation and/or precaution, not all medical services should and/or could be canceled within an organization, even if the number of accidents were zero [11].

Avoided Costs Related to Medical Treatment in Hospitals and Revalidation (Type I + Type II)

Some of the more severe occupational accidents need to be treated in hospitals by specialized personnel. This may also represent a substantial avoided cost:

Avoided Costs Related to Using Medical Equipment and Devices (Type I + Type II)

Avoided costs related to used medical equipment and devices is mainly applicable to companies having their own medical services. Depending on the nature and severity of the accident, employees can be treated in the medical facilities of the organization, and medical equipment, devices, and material can be consumed in such cases. First, well-educated medical personnel need to be present in the case of certain equipment. Such personnel and their training and education represent an avoided cost. Second, medical material may include bandages, painkillers, and so on.

Medical Transport Avoided Costs (Type I + Type II)

If an accident requires employees to be treated in hospital instead of by the organization's medical services, they need to be transported to the hospital. This transportation cost should be taken into consideration in a CBA.

5.4.2.8 Intervention Avoided Costs (Type I + Type II)

Whenever an accident occurs, and certainly in case of a major one, different types of intervention personnel will be needed. Intervention types can range widely and include fire services, police services, ambulance services, and special unit services if toxic material is involved in the accident. The option to include fire and police department costs should at least be considered, as in some cases the company will have to pay an amount of money for their services, although these interventions by the fire and police departments are public services [8]. The intervention avoided costs can be calculated by taking the sum of the avoided costs for the specified intervention types.

5.4.2.9 Reputation Avoided Costs (Type II)

Consequences related to the reputation of the company subject to a major accident are hard to quantify. One possible way to do so is by considering the share price consequences, as share prices display the investors' image of the current performance and future expectations of the company, which can be seen as the “reputation.”

Consider the example of the BP share price drop due to the Deepwater Horizon drilling rig major accident in April 2010. Following the oil rig disaster, the BP share price dropped more than 50% in value. On April 20, the day of the major accident, the share price was £655.40. As information regarding the severity and consequences of the disaster became widely known, the share price plunged, reaching a low of £302.90 on June 29, a decline of 53.78% in comparison to the April 20 share price. From this day on, the share price gradually increased again. The price seems to have stabilized around £450.00, a recovery of some 50% of its loss, although still some 30% below the pre-accident share price and pre-accident market value of about $190 billion.

The share price avoided costs can be calculated by multiplying the current total market value of the company by the expected drop in the share price.

A company can use a rule of thumb for the expected drop in share price and anticipate an expected decrease of share price (expressed as a percentage), depending on the consequences of a disaster scenario.

5.4.2.10 Other Avoided Costs

Accident Investigation Avoided Costs (Type I + Type II)

When an accident occurs, a person or a team is assigned to investigate it (not necessarily related to any legal affairs; see Section 5.4.2.3). Depending on local legislation and the type of accident, organizations are obliged to report it to the authorities through an accident investigation report [12]. Organizations also often want to determine and map the causes of accidents in order to take the necessary preventive measures to avoid future similar incidents. The literature thus mentions a variety of accident investigation approaches, each with pros and cons. The costs of accident analyses arise from the time that employees have to devote to the investigation, and sometimes also from technical studies. In the case of type II accidents, in particular, technical investigations may be an important avoided cost.

The time-related costs are composed of the wages of people carrying out the accident investigation. This cost can be determined by using the wage per employee category involved in the investigation [26]. Sometimes, certain additional employee-related costs are present that should be added to the costs. Such additional costs involve, for instance, the further processing of the accident investigation file, and sending the report to all concerned parties.

Manager Work Time Avoided Costs (Type I + Type II)

Managers of all levels (middle management, higher management and board of directors) will be forced to invest time if an accident occurs. They will have to investigate the accident, guide the employees, possibly deal with press attention and, in certain cases, attend lawsuits and other legal processes [7]. The manager work time consequences can be calculated and estimated by multiplying the total number of hours lost by all managers of a certain manager category by the cost per hour of the lost work time of managers of that category. As the work of managers with significantly varying wage levels will be affected, the manager work time consequences can be calculated separately for each category of managers.

These costs are represented by the following formula:

equation

where n is the number of manager categories.

Clean-up Avoided Costs (Type I + Type II)

An avoided cost that is often forgotten is the clean-up cost resulting from an accident. Before rebuilding and restoring the initial situation, the whole accident area needs to be cleaned up. Besides the employees, an independent cleaning company may sometimes need to be hired to execute this clean-up assignment. The avoided clean-up costs can be calculated and estimated by multiplying the hourly wage of an employee by the number of hours the cleaning will take, and again by the number of employees participating.

5.4.3 Investment Analysis (Economic Concepts Related to Type I Risks)

In the case of type I risks, certain economic concepts exist that are linked to the costs and benefits and help to make an investment analysis to steer a recommendation for the safety investment. The economic concepts are “internal rate of return” (IRR) and “payback period” (PBP).

5.4.3.1 Internal Rate of Return

The IRR can be defined as the discount rate at which the present value of all future cash flows (or monetized expected hypothetical benefits) is equal to the initial investment or, in other words, it is the rate at which an investment breaks even. Generally speaking, the higher an investment's IRR, the more desirable it is to carry on with the investment. As such, the IRR can be used to rank several possible investment options an organization is considering. Assuming all other factors are equal among the various investments, the safety investment with the highest IRR would then be recommended to have priority. Note that the IRR is sometimes referred to as “economic rate of return” (ERR).

An organization should, in theory, undertake all safety investments available with IRRs that exceed a minimum acceptable rate of return pre-determined by the company. Investments may, of course, be limited by availability of funds or safety budget to the company.

Because the IRR is a rate quantity, it is an indicator of the efficiency, quality, or yield of an investment. This is in contrast to the NPV, which is an indicator of the value or magnitude of an investment.

A rate of return for which the NPV, expressed as a function of the rate of return, is zero, is the IRR, r*. This can be expressed as follows, (Eq. (5.1)):

In cases where a first safety investment displays a lower IRR but a higher NPV over a second safety investment, the first investment may be recommended over the second investment. Furthermore, note that the IRR should not be used to compare investments of different duration. For example, the NPV added by an investment with longer duration but lower IRR could be greater than that of an investment of similar size, in terms of total net cash flows, but with shorter duration and higher IRR.

5.4.3.2 Payback Period

The PBP is calculated by counting the time (usually expressed as a number of years) it will take to recover an investment. Hence, a break-even point of investment is determined in terms of time. The PBP of a certain safety investment for type I risks is a possible determinant of whether to go ahead with the safety project or not, as longer PBPs are typically not desirable for some companies. It should be noted that the PBP ignores any benefits that occur after the determined PBP and, therefore, does not measure profitability. Moreover, the time value of money is not taken into account in the concept, and nor is the opportunity cost considered. The PBP may be calculated as the cost of safety investment divided by the annual benefit inflows.

Note that the payback calculation uses cash flows, not net income. The PBP simply computes how fast a company will recover its cash investment.

5.5 The Cost of Carrying Out Cost-Benefit Analyses

Although the demand for CBAs over time is increasing in organizations (as it is in society), it should be clear that it takes many resources (efforts of all kinds, such as time, skill, and money) to carry out a CBA in a good way, certainly also in case of safety investment studies. The reason for these resources for CBA is that, if carried out well, the technique is used to evaluate the ratio between all benefits and all costs of certain investments. Hence, financial terms need to be assigned to all categories of costs and benefits as displayed in the previous sections, to be able to calculate the so-called “cost-benefit ratio” as accurately as possible. If only partial information is used, or inaccurate information, the ratios will be incorrect and safety investment decisions may be influenced. So, carrying out a CBA in itself can be an important part of the expenditure of a safety investment study.

5.6 Cost-Benefit Analysis for Type I Safety Investments

It is possible to determine whether the costs of a safety measure outweighs – or not – its benefits. In general, the idea is simple, as previously explained: compare the costs of the safety measure with its benefits. As seen in the previous sections, the costs of a safety measure are relatively easy to determine, but the benefits are much more difficult to calculate. In the approach explained in this section, the benefits are expressed as the “reduced risk,” taking into account the costs of accidents with and without the safety measure implementation. The following equation may be used for this exercise [29]:

equation

Alternatively, if there is not enough information regarding the initiating events' frequencies to use this equation, the following equation can be used:

equation

where

equation

These formulas show immediately why this approach may only be carried out for (type I) risks where sufficient data are available: if not, the required “statistical frequencies” are unknown, the probabilities may not be known, and rough estimates (more or less informed guesses) will have to be used. If sufficient information is available, the results from these equations for determining the cost-benefit of a safety measure will be reliable.

5.7 Cost-Benefit Analysis for Type II Safety Investments

5.7.1 Introduction

In this section, a systematic approach to analyzing and evaluating safety investments aimed at preventing and mitigating type II risks, and based on the DF, is described and explained .

Type II accidents are related to extremely low frequencies and a high level of uncertainty. To take this into account, the CBA preferably involves a DF (see also Chapter 4 and Section 8.12) in order to reflect an intended bias in favor of safety over costs. This safety mechanism is vital in the calculation to determine the adequate level of investment in prevention measures, as, on the one hand, the probability influences the hypothetical benefits substantially through the number of years over which the total accident costs can be spread out, and on the other, the uncertainty regarding the consequences is high [31].

Usually, CBAs state that the investment is not encouraged if the costs are higher than the benefits. If, however, a DF is included, an investment in safety is reasonably practicable unless its costs are grossly disproportionate to the benefits. If the following equation is true, then the safety measure under consideration is not reasonably practicable, as the costs of the safety measure are disproportionate to its benefits:

In order to give an idea of the size of the DF, some guidelines and rules of thumb are available. They state that DFs are rarely greater than 10, and that the higher the risk, the higher the DF must be in order to stress the magnitude of those risks in the CBA. This means that in cases where the risk is very high, it might be acceptable to use a DF > 10 [31]. Although a value > 10 is allowed, Rushton [31] strongly advises against using a DF > 30.

This increase of the DF according to the risks is shown in Figure 5.3 (from Rushton [31]). This figure again indicates that CBAs should be used to evaluate safety measures for risks in the “as low as reasonably practicable” (ALARP) region. The more the risks leans toward the “intolerable” part of the ALARP region, the larger the DF needs to be.

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Figure 5.3 Disproportion factor (DF). ALARP, as low as reasonably practicable; B.A., broadly acceptable.

(Source: Rushton [31].)

Figure 5.3 highlights the principle that the higher the risk, the higher the DF must be, and that in cases where the risk is very high and tends toward the unacceptable region, it might be acceptable to use high DFs.

In brief, companies can demonstrate to governments and other people that additional measures are not reasonably practicable, based on CBAs taking a DF into account. An advantage of using a DF in the analysis is that the company can claim to be biased in favor of safety above costs. Note that in theory it would also be possible to use the DF for type I risks, if company safety management wished to pursue certain safety investments for this type of risk.

However, operational safety-related investment decisions should indeed be weighted in favor of safety, especially in case of high-impact, low-probability (HILP) risks. The process in practice is preferably not one of simply balancing the costs and benefits of measures, but rather of always implementing the safety measures (due to the high Maxmax hypothetical benefits in case of HILP risks; see Section 4.2.4), except where they are ruled out because they involve so-called “grossly disproportionate” sacrifices. As several factors come into play, there is no simple formula for computing which risks are situated in the “ALARP” region (see Section 4.10.1). Nonetheless, safety-related decisions need to be justified based on some form of economic analysis. Moreover, when comparing the sacrifice (investment cost of safety measure) and the risk reduction (hypothetical benefit of the safety measure), the usual rule applied by a CBA model is that the investment should be made if the benefit outweighs the costs. However, for making decisions in the tolerable part of the ALARP region, the rule is that the safety measure should be implemented unless the sacrifice is “grossly disproportionate” to the risk. By using this successful practice, the investment costs are allowed to outweigh the benefits, and the safety investment is pursued. However, the question remains as to what extent costs can outweigh benefits before being judged “grossly disproportionate.” The answer to this question depends on factors which are summarized by the DF. In Thomas and Jones [32], the concept of maximum justifiable spend (MJS) is introduced as follows:

equation

Maximum justifiable spend is the amount of money it is worth spending, based on the magnitude of the risk, to reduce the risk to zero. It gives a criterion for identifying what additional risk reduction measures are worth considering. We suggest that the measures being more costly than the MJS can be discarded immediately. Those that are lower than the MJS should be implemented in order to reduce the risk and contribute to achieving acceptable ALARP. There is also a gray area where additional assessment efforts are required. The formula can be used to rank and classify alternative safety measures, but it relies on preliminary computations and risk assessments about the level of the DF which should be employed and which can be considered realistic. The approach proposed in this section can be used to evaluate ALARP safety investments embedded within an economic ex ante risk.

In the following sections, a formula is presented to derive the value of the DF which makes the NPV of a safety investment equal to zero. Using the results of such a simulation exercise, it is possible to compare alternative safety measures. Moreover, given the limitations and restricted understanding of the three “How” factors (see Section 4.11.2.2), it is important to judge whether the DF associated with each safety measure “behaves” in a reasonable way.

5.7.2 Quantitative Assessment Using the Disproportion Factor

Three main features are associated with every safety investment, as shown in Table 5.8.

Table 5.8 Features associated with a safety investment to be evaluated

Symbol Description
V Total loss which results from the adverse event
f Financial loss
h Loss of human life
c Factor translating loss of human life into financial terms
p Likelihood that the adverse event will occur
n Time horizon in years
a Risk aversion factor
e Effectiveness of the safety investment expressed as a percentage
M Initial cost of the safety investment, including the installation, expressed in a specific currency
m Yearly recurring cost expressed as a percentage of the initial investment's cost, M

The cost of a safety investment can be divided into M (corresponding to the initial investments, e.g., the purchasing cost of new equipment and materials directly related to the intervention) and m (the yearly recurring costs due to maintenance, energy costs, yearly equipment, depreciation and interest expenses, material and training costs). A safety investment is evaluated considering a time horizon n that should be defined by the investor. More specifically, the time horizon should be compatible with the asset life of the safety measure to be analyzed. Hence, within n years, the safety investment is supposed to maintain its effectiveness, without any significant deterioration of its performance.

In order to assess the financial impact of a safety investment, the NPV equation should be adapted to the evaluation of the cost-effectiveness of a safety measure by explicitly including the DF. More specifically, the investment is represented by the cost of the safety measure to be evaluated (i.e., M). This cost is supposed to be entirely sustained in the initial year (year 0) when the investment needs to be evaluated. Owing to the characteristics of the measure, yearly recurring costs (e.g., due to maintenance activities) might be required over the time horizon in which the investment is evaluated. These recurring costs are needed to maintain the functionality of a safety measure and keep its effectiveness at its initial level. These costs are expressed as a percentage of the measure's initial cost and are assumed to be sustained starting from year 1 until n, where n represents the time horizon in which the investment is evaluated. Therefore the cost value Ct to be considered in the formula of the NPV assumes the following form:

On the other side, consistent with what was previously explained in this chapter, the benefits are quantified as the monetary savings that can be achieved if the disruptions caused by an accident, which might happen with probability p, are avoided or mitigated thanks to the safety investment that has been pursued. To quantify the savings, the basic notion of risk is used, as explained in Section 2.2. As defined by the Center for Chemical Process Safety [33], risk can be seen as an index of potential economic loss, human injury, or environmental damage, which is measured in terms of both the incident probability and the magnitude of the loss, injury, or damage. The risk associated with a specific (unwanted) event is thus expressed as the product of two factors: the likelihood that the event will occur (p) and its consequences (V) considering both financial and human aspects. A risk is therefore an index of the “expected consequence” of the unwanted event. Two types of losses (financial loss f and human loss h) are considered to quantify the value of V (see Talarico et al. [34] for more details):

equation

where c represents a factor translating human loss into financial terms.

Moreover, the risk aversion of a decision-maker toward a high-consequence accident scenario is also considered by using the risk aversion factor a. Together with the DF, the risk aversion factor a can be used as a parameter to balance the risk awareness of the decision-maker as a way to incentivize investments in safety.

Assuming further that a safety investment, whose effectiveness is represented by the letter e, is adopted, the risk of an accident can be decreased. In fact, the probability of an accident that might trigger consequences estimated to be equal to V can be lowered due to the safety investment as in the following formula:

equation

Assuming that no safety investment is pursued to prevent a potential accident, the expected risk is calculated by c05-math-0281. Therefore the profit of having a safety measure can be measured as the marginal savings that can be obtained compared with a case in which no investments in safety are made. More specifically, the marginal savings are represented by the avoided expected losses in the case of accident due to a lower overall risk. In the following equation, the marginal gain is shown:

equation

Finally, assuming that the safety investment allows one to decrease the risk of accidents during a fixed time horizon whose length is n, the total effect of the safety measure on the risk reduction can be estimated by multiplying the probability p by n. As a result, the potential benefits quantified in the year 0 can be assumed to have the following form:

5.7.3 Decision Model

During the risk assessment phase, risk experts analyze the features of a system that might potentially be affected by a HILP accident. Accident types are investigated and possible consequences are calculated. These consequences can also be estimated from a financial point of view, as described earlier. The probabilities of the accident scenarios are also estimated. Using this information, the expected risks associated with accident scenarios are quantified. In Figure 5.4, a decision model is presented that can be followed within an organization to assess, evaluate and decide about a safety investment regarding a type II accident scenario.

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Figure 5.4 General schema of the decision model for evaluating safety investments based on the disproportion factor (DF).

As can be seen in Figure 5.4, this risk assessment approach serves as an input for both a technical and a financial assessment. These phases can be executed in parallel, based on the findings of the previous step. The technical assessment is focused on the definition of the most suitable safety investments, based on the risks that might affect the system. A list of possible safety investments is drafted and for every possible investment some basic features are determined (e.g., installation cost, maintenance, effectiveness, duration). Moreover, some of the available investments might be not compatible, from a technical point of view, with the system that needs to be protected. For this reason, the incompatible measures should be discarded from the following steps of the analysis. Furthermore, the goal of the financial assessment is to define the safety budget, for example, discarding some safety investments as too expensive. Furthermore, some of the parameters required to estimate the benefits of the safety investments need to be defined, such as the discount rate and the time horizon to analyze the investment.

For every feasible safety investment, an evaluation is subsequently performed to analyze its financial impact and to determine the DF to make the safety investment profitable. A specific configuration might be required by the financial and technical assessment phase to evaluate the investment. This configuration provides specific information in terms of the features of the selected safety investment, time horizon, discount rate, and so on, which can be used to evaluate the investment. Moreover, several scenarios can be analyzed by carrying out a sensitivity analysis whereby the consequences and probabilities of accident scenarios are used as test parameters. Therefore, the main goal of the investment assessment is to assess the robustness of the choice under different scenarios and assumptions. More specifically, different configurations might be tested to explore how the DF, which is associated with the safety investment to be evaluated, is affected by changing one of the test parameters. Sometimes, the financial and technical assessments need to be reiterated in order to realign the technical and financial elements included in the decision model. For every possible safety investment, the proposed process can be repeated. In addition, other investments can be analyzed and compared with each other. In some cases, especially for HILP (type II) accident scenarios, where there is no consensus between risk experts, alternative scenarios, presenting, for example, higher or lower accident probabilities (cf. difference among the worst-case scenario, worst-credible scenario, most-credible scenario, etc.), might be considered. Afterwards, the whole decision approach is repeated to assess the impact on the safety investments to be selected.

The final step is represented by the decision-making in which alternative investments are evaluated on the basis of elements such as the DF for which the NPV is equal to zero; substituting Eqs. (5.2) and (5.3) into Eq. (5.6) and going from an inequality to an equality, we obtain the formula for the break-even DF:

9 equation

where Eqs. (5.7) and (5.8) are substituted into Eqs. (5.2) and (5.3), respectively.

The lower the DF, the better the investment from a financial point of view. Different simulations can be carried out, such as comparing safety investments given an accident scenario (consequence and likelihood) and/or configuration, such as the time horizon.

5.7.4 Simulation on Illustrative Case Studies

In this section, some sensitivity analyses are carried out to simulate the decision process of evaluating safety investments in a realistic scenario. Section 5.7.4.1 describes the features of the safety measures and the values of the main technical and financial parameters which are considered in the illustrative case studies, while Section 5.7.4.2 provides some recommendations and explanations for the outcomes of the simulation exercise.

5.7.4.1 Input Information

The decision model described in Section 5.7.3 has been widely tested on realistic data representing some safety measures used in chemical plants to prevent and/or mitigate domino effects (see Janssens et al. [35] for more details). More specifically, the safety measures listed in Table 5.9 have been used to validate the decision model described earlier.

Table 5.9 Features of the safety investments

Safety investment number Description M (€ millions) e (%)
1 Concrete wall surrounding tank of 25 m + sprinkler without additional foam 15 95
2 Automatic sprinkler installation with additional foam 10 93
3 Automatic sprinkler installation without additional foam 8 90
4 Deluge system (water spray system opened as signaled by a fire alarm system) 4 86
5 Fire-resistant coating 2 81

A full factorial experiment has been carried out, testing the effects on the selected safety measures for different scenarios (summarized in Table 5.10) and technical and financial configurations (summarized in Table 5.11).

Table 5.10 Possible scenarios after the risk assessment

Scenario characteristic Value
Types of accident scenario Vapor cloud explosions and fires
BLEVE without chemical reactions
BLEVE with chemical reactions
Maximum estimated damages potentially triggered by the accident scenario (V) €0.5 million, €1 million, €2 million, €5 million, €10 million
Probability of the accident scenario (p) 10−4, 10−5, 10−6, 10−7, 10−8
Risk aversion factor (a) 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6

BLEVE, boiling liquid expanding vapor explosion.

Table 5.11 Technical and financial parameters

Parameter Value
Discount rate (i) 1%, 2%, 3%
Yearly recurrent cost (m) 1%, 3%, 5%, 10%
Time horizon (n) 5, 10, 15, 25 years

5.7.4.2 Results and Recommendations

A sensitivity assessment was performed using both the outcomes of the risk assessment (see Section 5.7.4.1) and the test parameters (including the consequences and the probabilities of a potential accident) to evaluate possible safety investments. The analysis is carried out by fixing some of the parameters decided during the risk, financial, and technical assessments and analyzing the influence of the parameters which are not fixed on the DF. In the remainder of this section, if not explicitly mentioned, the basic parameters summarized in Table 5.12 have been used to generate the graphs.

Table 5.12 Basic parameters setting used in the simulation

Parameter Value
Risk aversion factor (a) 1.45
Yearly recurring cost (m) 3%
Time horizon (n) 25
Discount rate (i) 2%
Probability of accident (p) 10−5

In Figure 5.5, five safety investments are assessed based on the calculated DF whereby the NPV equals zero and considering different scenarios in which three accidents scenarios, and hence three hypothetical benefits (i.e., €2 million, €5 million, and €10 million), are considered during the risk assessment phase. From now on the value of the DF that makes the NPV equal to zero is denoted by DF0 to avoid confusion and simplify the reading. As expected, measure 5 (i.e., “fire resistant coating”; see Table 5.9) presents a lower DF0 because the investment it requires is lower compared with the other measures. Therefore, from the viewpoint of the safety investor, the benefits are more proportionate to the costs. With reference to measure 1, a higher DF0 needs to be used to justify the selection of this measure that nevertheless has a higher effectiveness to prevent and mitigate major accidents. As shown in Figure 5.5, when the potential benefits of preventing major accidents are higher, the DF0 values associated with the different safety investments decrease. This result is justifiable from a decision-maker's perspective because investments are more proportional to potential savings.

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Figure 5.5 DF0 [the disproportion factor (DF) that makes the net present value (NPV) equal to zero] associated with alternative safety investments, while evaluating different accident scenarios.

It should be noted that sometimes low safety investments imply the use of simple safety measures (e.g., measures 4 and 5 in Figure 5.5), which might not be a viable option for major accidents due to technical and safety reasons (e.g., a reduced effectiveness to prevent major accidents). Therefore, these investment options should be discarded during the risk assessment phase, while considering catastrophic accident scenarios.

Impact of Different Accident Scenarios on DF0

After having shortlisted the investments to be analyzed in the decision process, one might consider focusing on a single safety investment to assess its robustness by studying the relationship between its main features and the DF0. In this way, alternative options can be compared more adequately and can be assessed using a multidimensional decision-making approach. For example, in Figure 5.6 a specific investment (investment 3, “Automatic sprinkler installation without additional foam”) with a fixed parameter setting (see Table 5.12) is investigated. Assuming three different accident scenarios (and thus three different values of hypothetical benefits), a simulation on the relationship between the DF0 and the NPV is shown. As expected, the higher the potential benefit, the lower the DF0 required to make the investment profitable. Analyzing Figure 5.6, one can see that the safety investment can be justified from a financial point of view only if the hypothetical benefits are greater than €2 million. In fact, for minor accident scenarios (in this case hypothetical benefits of €2 million or lower), the total costs of the investment can compensate the potential benefits, only when assuming a DF > 30. As values of DF > 30 are generally considered by investors to be very high or even too high, the measure may not represent a reasonable investment from an economic perspective and thus should be ruled out when the accident scenarios that might affect an organization are triggering “minor” consequences. For accidents with a significant impact, triggering damages of, say, €5 million or €10 million, the measure presents a zero NPV for DFs equal to 10.9 and 4.0, respectively. Obviously, these DFs are < 30 and can thus be considered reasonable according to Goose [30], implying that the measure represents a viable safety investment in the case of major accidents.

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Figure 5.6 Net present value (NPV) and disproportion factor (DF) associated with different accident scenarios.

In Figure 5.7, the impact of the probability of a potential accident is assessed. In particular, the higher the probability, the lower the value of the DF0 that is needed to make the investment profitable from a financial point of view. If the probability of the accident is very low, the decision-maker will tend to avoid safety investments, as the hypothetical benefits are more uncertain and more disproportionate than the costs. For this reason, a higher DF is required to stress the importance of safety in the case of HILP accidents.

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Figure 5.7 Relationship between the probability of an accident and the DF0 [the disproportion factor (DF) that makes the net present value equal to zero] associated with different scenarios.

Impact of Technical and Financial Parameters on DF0

Focusing on a specific safety investment, the relationships between financial and/or technical parameters and the DF0 can be explored further. In Figure 5.8 the relationship between the yearly recurring costs and the DF0 is shown for a specific safety investment (measure number 2, “Automatic sprinkler installation with additional foam” in this case), while considering hypothetical benefits of €5 million. The other technical and financial parameters are set to the values reported in Table 5.12. As expected, the greater the yearly recurring costs, the higher the DF0 due to increased sacrifices in safety required by a firm (see Figure 5.8). A simulation also considering different time horizons, in which the safety measure can maintain its effectiveness, has been performed. As shown in Figure 5.9, the longer the time over which the safety investment can maintain its effectiveness before becoming obsolete, the more attractive the investment will be and thus the lower the DF0. In fact, the shorter the time horizon, the higher the DF0 should be to make the investment desirable, due to a shorter time period for the return on investment.

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Figure 5.8 Relationship between DF0 [the disproportion factor (DF) that makes the net present value equal to zero] and the yearly recurring costs for different time horizons.

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Figure 5.9 Relationship between the disproportion factor (DF) and the asset life for different maintenance costs.

Still considering safety investment number 2, the same accident scenario analyzed previously, and using the technical and financial parameters as in Table 5.12, Figure 5.10 illustrates the relationship between the discount factor used to calculate the NPV and the DF0. Figure 5.10(a) shows that the DF0 remains stable for different values of the discount rate given a fixed time horizon. Moreover, the longer the time horizon over which the investment is analyzed, the lower the DF0. As shown in Figure 5.10(b), the DF0 is not significantly affected by a variation in the discount factor as long as it remains under a certain level. However, the DF0 can vary depending on the maintenance cost that is considered. In addition, when the maintenance costs are high, an increase in the discount factor can trigger a decrease in the DF0.

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Figure 5.10 Relationship between DF0 [the disproportion factor (DF) that makes the net present value equal to zero] and the discount factor: (a) for different time horizons; (b) for different yearly recurrent costs.

Impact of the Risk Aversion Factor on the DF0

Finally, the relationship between a decision-maker's risk attitude and the DF0 can be assessed. Figure 5.11 represents the evolution of the DF0 when the risk aversion factor assumes different values for two different safety investments. Moreover, the lower the potential benefit, the lower the DF0 that would be used by the decision-maker to evaluate the investment (see Figure 5.11a,b). As expected, the lower the investment required for a safety measure, the lower the DF0 that is needed to make the investment proportional to the potential benefit. When the value of the risk aversion factor increases, it means that the decision-maker is more risk-averse and will therefore be more inclined toward safety investments. As both the discount factor and the risk aversion factor can be used as a bias in favor of safety, when the value of a increases there is a reduced need to use the DF0 as an incentive for investments in safety.

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Figure 5.11 Relationship between DF0 [the disproportion factor (DF) that makes the net present value equal to zero] and the risk factor for different accident scenarios. (a) Potential benefits equal to €2 million; (b) potential benefits equal to €5 million.

5.7.5 Recommendations with Regard to Using the DF0

A structured approach to carry out a quantitative CBA for safety investments aimed at HILP (type II) risks has been presented. A DF has been used to make safety costs comparable with the hypothetical benefits that such investments might trigger due to accident prevention. A decision model is presented showing a possible approach to assessing and evaluating mid- to long-term safety decisions considering technical, financial and risk management aspects. The goal of the methodology is to define the level of DF that makes the investment profitable from a financial point of view. The approach can be used to classify and rank alternative investments, rather than define ideal levels of DF that make the safety investment profitable. These latter levels may depend on several factors such as the type of industry, the type of accident, the reputation of the organization, the legal framework, and so on. However, to support the decision process and the selection of the ideal safety investment for a certain accident scenario, one should consider that reasonable values of DF might lie in the range 1–30 [30]. In light of this, safety investments with DF0 (i.e., the DF at which the NPV becomes zero) outside of these ranges can be discarded. For this reason the methodology presented here can be used to shortlist and rank alternative options and provide quantitative rationales for decision-makers to justify safety investments.

Similar to other financial indicators and ratios (e.g., NPV, IRR), in which recommendations are provided to support decision-making, here it is suggested that, assuming all safety investments require the same initial investment, the alternative with the lowest DF0 falling in an interval that is considered reasonable would be the best option from a financial point of view.

A simulation has been performed, analyzing the relationships between the main financial and technical parameters and the DF. This information can be used by decision-makers to compare and analyze alternative safety investments that can be effectively adopted to prevent and mitigate specific accident scenarios. To conclude, the quantitative assessment of safety investments using the DF and the NPV is a complex topic. Despite the sensitivity simulation approach proposed in this section being quite flexible and easily adjustable by the decision-maker, it represents a first attempt to introduce this topic in the literature (see also Section 8.12).

5.8 Advantages and Disadvantages of Analyses Based on Costs and Benefits

It should be remembered that the lack of accuracy associated with CBAs can give rise to significantly different outcomes in assessments of the same issues by different people. In addition, it is often much easier to assess all kinds of costs than to identify and evaluate the (hypothetical) benefits and their probabilities.

Cost-benefit analysis can best be used for type I risks, where a sufficient amount of information and data are available to be able to draw sufficiently precise and reliable conclusions. If it is used for type II risks, it risks creating an image of accuracy and precision that is unrealistic. In that case, it is important to take moral factors into account in the calculation, besides the rational information based on the group risk curve. This can be realized by using a so-called adjusted DF (see Section 4.11.2.3) in the case of CBA for type II risks. Furthermore, investigating the DF with respect to several parameters to verify when the NPV becomes zero, and making decisions based on this sensitivity assessment knowledge are also recommended (see also Section 5.7).

In summary, it is often difficult to incorporate realistic calculations of the NPV of future costs and benefits into the analyses. This is a very difficult prediction exercise with a lot of uncertainty involved. Nonetheless, techniques based on costs and benefits that are used to make prevention decisions have one major undeniable strength: if used correctly, they allow limited financial resources to be allocated efficiently and adequately for carrying out safety investments.

5.9 Conclusions

Cost-benefit analyses in case of safety investments constitute much more than calculating the costs of actual accidents, or determining the costs of prevention. Hypothetical benefits, the benefits gained from accidents that have not occurred, should be considered, and type I as well as type II risks should be taken into account when dealing with prevention investment choices. Decisions concerning safety investments make up for a complex decision problem where opportunity costs, perception and human psychology, budget allocation strategies, the choice of cost-benefit ratios, and so on, all play an important role.

The NPV can be defined as the net value on a given date of a payment or series of payments made at other times. If the payments are made in the future, they are discounted to reflect the time value of money and other factors such as investment risk. NPV calculations are widely used in business and economics to provide a means to compare cash flows at different times on a meaningful “like for like” basis. Discounted values reflect the reality that a sum of money is worth more today than the same sum of money at some time in the future. Therefore, in CBAs, prevention costs incurred today should be compared with hypothetical benefits obtained at some time in the future, but equated to today's values.

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