Uncertainty and Risk in Civil Engineering Practice

Basic Considerations

As human beings, ... being alive means seeking opportunities and taking risks. As knowledge professionals living in the 21st century, this means coping with an increasingly complex number of uncertainties for humans living in this environment. We seek to understand better how these uncertainties can be characterized and managed. The essence of this article and the experience for engineers in general and civil engineers in particular is that manageable uncertainty is, by definition, termed risk, and its kindred cousin is termed hazard. This causes us to experience the

" ... human dread of and fascination for risk and the increasingly important role of risk analysis within societies ... " cite note-2 1/23

(Ibid.) and, by extension, civil engineering. McDaniels et al. argue that risk management has been fundamental to our social and governance development for the past 10,000 years. The scale and shape of the uncertainties faced in this period shaped the societies that have developed today. The central thrust of this effort over the centuries has been to reshape and re-frame our understanding and conception of uncertainty from one of complete unknowing and simple acceptance as our fate in life to one of management (cf"Against the Gods" concept in Bernstein's book [21). All the knowledge professions and disciplines have struggled with managing uncertainty for it is impossible to manage unbounded uncertainty. [Note 1] As will be outlined below, the reason why professions such as civil engineering have been successful acting in the face of uncertainty lie in the profession's ability to reduce a broad variety of uncertainties into a series of increasingly smaller and crucially, bounded subsets that can be managed. These are called 'risks. More recently, this process has evolved to the point where individual disciplines such as Civil Engineering (CE) has developed their knowledge and models to perform risk analysis. Risk is also being taught as a distinct discipline and specialty practice within Civil Engineering but it has some unique features that set it apart from other more classical practices within CE. AS such it is one of the first of some very specialized CE practices that use knowledge about civil engineering knowledge, or meta-knowledge. Other examples of civil engineering metaknowledge are project controls and quality controls.

American Association of Cost Engineers (AACE)

AACE defined uncertainty, risk, and other related terms in its Risk Management Dictionary. AACE's overall strategy was to define risk and other terms that stem from base uncertainty. AACE first defined uncertainty as .... "(t)he total range of events that may happen and produce risks (including both threats and opportunities) affecting a project (see opportunities, events, conditions, risk, and threats" where the following sub-definitions apply:

• • Biases--A lack of objectivity based on the individual's position or perspective. Systematic and predictable relationships between a person's opinion or statement and his/her underlying knowledge or circumstances. Note: there may be "system biases" as well as "individual biases."
  • Condition (Uncertain Condition)-Any specific identifiable circumstance (such as the rate of inflation or the quality of labor available) that might affect the outcome of the project
  • Event (Uncertain Condition)-is a specific identifiable action (such as a large government project being started in the same labor area as your project) or an act of nature that might happen and that (if it does happen) could affect the outcome of the project.
  • Opportunities are Uncertain events that could improve the results or improve the probability that the desired outcome will happen
  • Threats are Uncertain events that are potentially negative or reduce the probability that the desired outcome will happen.
    • AACE defines Risk as an "ambiguous term" (sic) that is synonymous with uncertainty or a negative subset such as "threats", or an overall negative impact of all possible uncertainties.

Limitations of the definition

...

Working definition

...

Beneficial outcomes

...

See also

Wiki articles on the project.

Top of current page

Notes

1. See McDaniels et al. 2004 for an extensive discussion and bibliography on the historical development of Risk Analysis and some key milestones in the 20th century.
2. Open item
3. The Merriam-Webster dictionary defines uncertainty:

"the quality or state of being uncertain," which is a circular definition. Likewise, one could define uncertainty as the state of not being certain. Synonyms are distrust, doubt, misgiving, mistrust, reservation, skepticism, and suspicion. Another writer added indefinite, indeterminate, not certain to occur, problematical, unreliable, untrustworthy, unknown beyond doubt, dubious, doubtful, not clearly identified or defined, not constant, variable, and fitful to the list.

Han, Paul KJ, William MP Klein, and Neeraj K. Arora. "Varieties of Uncertainty in Health Care: A Conceptual Taxonomy." Medical Decision Making 31.6, (2011 ): 828-838.

Han, ct. al. noted that any definition of uncertainty encompasses " ... numerous types, sources, and manifestations of uncertainty, and ... (any) ... useful working definition of uncertainty needs to specify the concept underlying these varied meanings of the term." (Ibid.)

4. Implicit in this definition of uncertainty as a "state of' is ...

" ... a conceptualization of uncertainty as a subjective, cognitive experience of people--a state of mind rather than a feature of the objective world. Furthermore, the defining feature of this state appears to be a lack of knowledge about some aspect of reality. Importantly, however, the concept of uncertainty also implies a subjective consciousness or awareness of one's lack of knowledge, without which one could not feel uncertain; uncertainty is a form of "meta-cognition" ... ( or alternatively, its main component, meta-knowledge) ... -a knowing about knowing." (Han, 2011, op. cit., Emphasis added)

5. Cox wanted his system to satisfy the following conditions:

Divisibility and comparability- The plausibility of a statement is a real number and depends on the information we have related to the statement.

Common sense - Plausibilities should vary sensibly with the assessment of plausibilities in the model.

Consistency - If the plausibility of a statement can be derived in many ways, all the results must be equal.

Cox's theorem has come to be used as one of the justifications for the use of Bayesian probability theory. (For example, in Jaynes Jayne, Probability Theory: The Logic of Science, Cambridge University Press (2003). -preprint version (1996) at http://omega.albany.edu:8008/JaynesBook.html; Chapters 1 to 3 of published version at http://bayes.wustl.edu/etj/prob/book.pdf

6. The utility of existing taxonomies of uncertainty in civil engineering and, by extension, "risk" has been unsatisfactory for this very reason. This is particularly true in cases where the source of the uncertainty is conflicting versus incomplete information. See Regan, et. al.,"A taxonomy and treatment of uncertainty for ecology and conservation biology" (2002) for a survey of scientific taxonomies for uncertainty.
7. Regan et al. argue that " ... genuine examples of this kind of uncertainty are hard to find. Even classic cases of random experiments like coin tosses and the throwing of dice are deterministic; it is just that we do not have enough information about the dynamic processes and initial conditions to make any sensible estimates about the outcomes. Such processes are, for all intents and purposes, inherently random, but they are not genuinely inherently random. For similar reasons, complex systems such as ecosystems and weather patterns are unlikely to be inherently random. Similarly, chaotic systems are entirely deterministic. They are unpredictable because the deterministic processes generating them and the relevant initial conditions are hard to fully specify (see Stewart 1989, Sugihara et al. 1990)." (Regan (2002)
8. The CEBoK uses the phrase "uncertainty and risk" twice in reference to scheduling (Section 6.5,2) and cost estimating (Section 7.2,2) as well as reversing the two (Risk and Uncertainty) also in two places in discussing project life cycle (both in Section 2.4.1)