Engineering Ethics: Safety and Risk

• Chapter 5 focuses on engineering ethics, specifically safety, risk assessment, and historical case studies.
• Catastrophic failures show how vulnerable machines and control systems are, especially when human safety is involved.
• Special attention should be be paid to the need for safe exits in engineered systems due to their ever-growing complexity

Safety and Risk

• Safe products and services are demanded
• There is recognition that safety may come at a cost.
• Safety levels are subjective, as different individuals have varying perceptions and predispositions to harm.
• Absolute safety is unattainable because it is impossible to have entirely risk-free activities or products, as well as a degree of safety that satisfies everyone under all conditions.
• An engineer's most important duty is to protect public safety and well-being.
• Safety is being free from hurt, injury, or loss, while risk is the possibility of suffering harm or loss.
• Safety could be defined as:
  • Acceptable risk
  • Absence of risk
  • Risks judged acceptable by a reasonable person given that risks are fully known

Concept of Safety

• William W. Lowrance stated a thing is safe if its risks are judged to be acceptable, thus safety is a value judgment and is influenced by different values.
• One problem with Lowrance's definition is it may not be consistent with a common sense idea of safety.
• There are three issues with Lowrance definition
  • Risk can be underestimated
  • Risk can be overestimated
  • There can be a lack of judgement about risk
• Objective definitions suggest that safety is the absence of risk, but this is not the case in engineering.
• A modification of Lowrance's definition suggests that a thing is safe if the risks were fully known and would be judged acceptable by a reasonable person in light of their settled value principles.
• Risk calculation may be objective, but it's acceptability is subjective.
• Degrees and comparisons can be indicated with qualifiers like fairly, relatively, certainly, mostly, and sometimes.
• Airplane travel exemplifies being described as safer than automobile travel per mile traveled.

Risks

• Risk is the potential for something unwanted and harmful to occur.
• Risk is taken when using or doing something unsafe.
• Risk encompasses bodily harm, economic loss, and environmental degradation.
• Technology's impact on society has increased public concern about risk and safety.
• Education, experience, and media attention are driving visibility of risks.
• Modern construction has caused some risks from natural hazards to diminish, while earthquakes have had elevated risk.

Acceptability Risks

• According to William D Rowe, a risk is acceptable when those affected by it are generally no longer apprehensive about it.
• Apprehension depends on:
  • Voluntarism and control - Risks are less of a concern when exposure is voluntary.
  • Effect of information on risk assessments - altering one's perception of risk through certain types of information
  • Job-related risks - People will typically continue doing risky activities if there are no other options.
  • Magnitude and proximity - The impact of future risk is easily dismissed.

Assessing and Reducing Risk

• Safety improvement in engineering comes with increased cost.
• Product cost = primary cost + secondary cost
• Primary cost includes design, development, testing, manufacturing, and distribution
• Secondary costs include warranty expenses, lawsuits, loss of customer goodwill, and downtime which are also associated with products
• Total cost is the sum of primary and secondary costs.
• The relationship between the two are: low risk/high safety (high primary cost, low secondary cost) and high risk/low safety (low primary cost, high secondary cost) are expensive approaches.
• The lowest total cost comes with a reasonable balance which produces an economically optimum balance between risk and safety.

Safe Design

• Complying with laws, meeting standards, exploring alternative designs, and minimizing risks is neccessary for safe design.
• Designing for safety includes defining the problem with all necessary constraints, generating and analyzing solutions, testing and then selecting the best solution and implementing said solution.

Uncertainties in Design

• Unreliability relates to past experience and data that may often be unreliable when it comes to safety due to problems not being shared unless absolutely necessary and developments in materials making older information less useful.
• Risk often arises from incomplete knowledge.
• Risks must be mitigated through
  • Calculation of Safety factor C/D which measures probability of product being able to do likely task VS product being likely to be assigned. This can be limited as it does not account for every variability that may occur
  • Calculation of margin of safety which measures lowest capability level versus highest duty level, and is a more accurate indication of safety.
• Introducing a "factor of safety" helps Engineers cope with uncertainties about materials or incomplete knowledge.
• A factor of safety protects against stress deviations between loads and the product's design.

Risk-Benefit Analyses

• Risk-benefit analysis helps justify large projects, especially public works, by addressing if a product is worth the risks and what the benefits are.
• A close look at risk-benefit analysis unveils conceptual difficulties as risk and benefits are in the future.
• Calculations of magnitude of the potential loss should be proportionate to the likelihood of the loss with emphasis on the gain.
• It must be known who establishes these values and how.
• If benefits are realized near and risk is far, it should be considered how future discounting may affect the overall values

Risk Factors

• Asking if benefits outweigh risks is essential before proceeding.
• Acceptability relates to:
• The level of risk tolerance for certain gains.
• Conceptual problems that must be included are:
• Multiplying the potential losses and gains by their probabilities.
• If all the values change plans.

Problems with Project Analysis

• Time relates to understanding how to balance short term gains versus long-term risks.
• Distribution is how benefits to one can potentially cause risk to another.
• Commensurability relates to putting varying types of benefits or risk on a scale.
• Creep indicates that a project analysis is not a design comparison.

Personal Risk

• Individuals should decide whether or not to take part in risky activity, given enough information.
• People will have a stronger preference for voluntary risk versus not chosen risk taking.
• Personal risk assessment requires an open and not completely objective procedure to identify variable.

Public Risk and Public Acceptance

• Satisfactory statistical averages can only occur when a population is large.
• Wide assessment studies are easier when individuals are not involved.

Improved Safety can be achieved through:

• Refrigerator door catch which can now be opened from the inside in case of a child getting stuck
• "Dead man handles on power tools, which allow a tool to turn off instantly if the user lets go
• Railroad signals of the 'semaphore' type now use gravity to return to default "STOP" mode and prevent any potential collision if malfunction occurs.

Safe Exits

• Designing for problems is essential and can be achieved through the following
• Making the product fail safely and ensuring proper abandonment so the user can safely escape the product.
• All parties should give valid consent for each product.
• Safe exits include safe disposal, system fail safes, and emergency procedures.
• It must be simple or easy to report hazardous conditions. Emergency procedures must be designed and implemented to create proper environments in crisis.

3 Mile Island incident Summary

• The 3 Mile Island Incident began March 28, 1979 when a malfunction occurred followed by a valve which leaked nuclear reactor coolant.
• There was an untrained staff which caused a loss of control.
• The incident ended after 5 days due to staff evacuating area and taking control of situation.
• 97% capacity was occurring at the reactor
• The accident was caused when attempts were made to fix eight condenser polishing devices as filter devices in water lines had blockages
• The filters prevent mineral build up
• Air pressure was used to solve the problem which caused water to flow into an antenna device.
• This caused pumps and turbines to shut down

Chernobyl Incident Summary

• The Chernobyl disaster began April 26 1986 in Pripyat Ukraine at Reactor No. 4.
• An reactor explosion occurred for many reasons including design flaw
• A reactor process used graphite columns and made for a unstable generator that engineers could not properly fix.
• $3 billion in loss of materials
• 36 deaths and 2000 injuries
• Closed in 2002
• A disaster zone was created
• Over 100,000 Evacuated
• The reactor was quickly covered in concrete but currently concrete has had major cracking and needs to have a protective layer installed.