Marvin Rausand - Risk Assessment

8 2.8 In this chapter, reference accident scenario, worst‐case accident scenario, and worst credible accident scenario are defined.(a) What are the differences between these three?(b)b Do you see any challenges in defining these scenarios in a practical case?

9 2.9 What are the differences between the two concepts robustness and vulnerability?

10 2.10 There are numerous definitions of the word “risk” and Section 2.2provides a definition and lists some alternatives. Compare the alternative definitions of risk provided and see how they differ from the definition used in the book.

11 2.11 Search the Internet for the word “risk” to see how this is used in different contexts, e.g. in media, and how the everyday use of the word compares to the formal definition. Some examples to look for are situations where risk is used synonymous with hazard, safety performance, and frequency.

12 2.12 Compare the terms incident and hazardous event and discuss the similarities and differences between these terms. Use practical examples and discuss the terms based on these rather than discussing purely from a theoretical viewpoint.

13 2.13 Assume that a bicycle has a brake system with a handle on the handlebars, a wire running from the handle to the brake pads, and finally brake pads that make contact with the wheel when the handle is pulled. Identify relevant failures, failure modes, and failure mechanisms for the brake system. Classify the failures according to the cause of the failure and the degree of the failure.

14 2.14 Consider the hazardous event “Car hits back of car in front while driving” and describe this event in a bow‐tie. Identify relevant barriers.

15 2.15 Consider the hazardous event “Fire in student flat” and describe this event in a bow‐tie. Identify relevant barriers.

16 2.16 Compare Definitions 2.31and 2.33for safety and security, respectively. Discuss the difference between these two definitions and suggest an alternative definition for security.

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1 1 The tolerability of risk is discussed in Chapter 5.

2 2 The main terms are defined and discussed later in this chapter.

3 3 Human errors are discussed further in Chapter 15.

The terms “risk analysis” and “risk assessment” are used several times in Chapters 1 and 2 without any proper definition. We define the terms as follows:

A systematic study to identify and describe what can go wrong and what the causes, the likelihoods, and the consequences might be.

A risk analysis is, according to Definition 3.1, aimed at providing answers to the three questions used to define risk.

The process of planning, preparing, performing, and reporting a risk analysis, and evaluating the results against risk acceptance criteria.

Figure 3.1Risk assessment as a combination of risk analysis and risk evaluation.