Chapter 7: Risk, Safety and Liability in Engineering

How should engineers deal with issues of risk and safety?

Engineering necessarily involves risk.

New hazards could be found in products, processes, and chemicals that were once thought to be safe.

Risk

Risk increases because engineers are constantly involved in innovation.

New machines are created and new compounds synthesized always without full knowledge of their long-term effects on humans or the environment.

In this chapter we will go over

The codes and engineering practice regarding risk and safety

Difficulties in estimating risk

Normalizing deviance

Three approaches to acceptable risk: experts, laypersons and government regulators approach to acceptable risk

The Engineers liability for risk

Becoming a responsible engineer regarding risk

The codes and engineering practice regarding risk and safety

All engineering codes say that: “Engineers must hold paramount the safety, health, and welfare of the public.

NSPE:II1b. Engineers shall approve only those engineering documents that are in conformity with applicable standards.III2b. Engineers shall not complete, sign, or seal plans and/or specifications that are not in conformity with applicable engineering standards. If the client or employer insists on such unprofessional conduct, they shall notify the proper authorities and withdraw from further service on the project.

II1a. If engineers' judgment is overruled under circumstances that endanger life or property, they shall notify their employer or client and such other authority as may be appropriate.

Difficulties Estimating RiskDetecting Failure Modes:A failure mode is a way in which astructure, mechanism or process canmultifunction.

Fault-Tree Analysis: a diagram of the possible ways in which a multifunction or accident can occur. Event-Tree Analysis (similar with diff. Appr.)

Fault-Tree Analysis

In a Fault-tree analysis one starts with an undesirable event, and then reasons backward to determine what might have led to the event. (p149)

Fault-Tree Analysis used to discover why a car wont start

F au lt Tree

1. R ust2. C orros ion3. D irt4 . Loose connections

1. lig hts le ft on m otor o ff2 . A g e3. B ad w eather4. D efectiv e ..........

1 . F aulty g round corrections2. Term inals loose or corroded3. B atery w eek

B attery C harg e Insuff ic ientTyp e title here

S tarting S ystem defectiv eTyp e title here

F uel S ystemD efectiv e

ig n ition systemdefectiv e

C ar W ont S tart

Event Tree-Analysis

In event-tree analysis one begins with an initial event and reason forward to the state of system to which the event can lead. (p.150)

These have limitations p.150

Are There Normal Accidents?

Two characteristics of high-risk technologies that make them susceptible to accidents:

Tight Coupling and

Complex Interactions of the parts of technological systems

**These two factors make accidents likely and difficult to predict and control

Processes are TIGHTLY COUPLED if they are connected in such a way that one process is known to affect another and will usually do so within a short time.

Ex: A chemical plat is tightly coupled because the failure in one part of the plant can quickly affect other parts of the plant.

Ex: A university is loosely coupled, why?

Processes are COMPLEXLY INTERACTIVE if the parts of the system can interact in unanticipated ways. Like no one expected that when part B failed it would affect part C.

Examples of complexly interactive and tightly

coupled technical systems: chemical plants, nuclear power plants, space missions, nuclear weapon systems. These can have unexpected failures, and little time to correct the problems. (all system affected)

The answer is:

It may not be possible to make a system both loosely coupled and noncomplex therefore accidents in complex, tightly coupled systems are inevitable and “Normal” (Perrow).

Students should read page 151-152: an example of an accident in a system that was complexly interactive and tightly coupled and that could have been prevented by good engineering.

Normalizing DevianceEngineers increase the risk to the public by allowing increasing numbers of deviances from proper standards of safety and acceptable risk.

This is called normalization of deviance.

Accepting anomalies instead of attempting to correct a design or operating conditions that led to the anomalies make accidents inevitable! (page 153 example from the challenger disaster)

Technology imposes RISK on the public RISKs are often difficult to detect and

eliminate

Three approaches to acceptable risk

The Experts Approach

The Layperson’s Approach

The Government Regulator’s Approach

Experts Approach to Acceptable Risk

Identifying risk:

Utilitarianism and acceptable risk

Risk as maximizing benefit

Identifying risk

concept of risk involves adverse effect or harm. Harm is a limitation of a persons freedom or well being. (physical well being, psychological well being, economical well being)

Risk can be defined as: “a compound measure of the probability and magnitude of adverse effect” (William W. Lowrance)

We can add : “probability of death or injury”

Utilitarianism and Acceptable riskThe experts approach to risk is usually utilitarian. That the answer to any moral question is to be found by determining the course of action that maximizes well being.Cost/benefit technique is often called risk/benefit analysis. Cost is measured in terms of risk of deaths, injuries, or other harms associated with a given course of action. (Ex: page145 and 155: is the risk to the workers from the fumes acceptable? ).

Risk as maximizing benefit

An acceptable risk is one of where , given the options available, the risk of harm is at least equaled by the probability of producing benefit.

Limitations: (that will yield the cost/benefit approach inconclusive)

It might not be possible to anticipate all of the costs and benefits associated with each option

It is not always possible to translate all of the risks and benefits into monetary terms. What is the monetary value of human life?

The method makes no allowances for the distributions of costs and benefits.

The method gives no place for informed consent to the risk imposed by technology.

The Laypersons Approach to Acceptable Risk

Expert and Layperson

Public is sometimes mistaken in estimating the probability of death and injury from various activities of technology. Experts and lay person understand risk differently.

Informed consent and justice: lay person approach follows more closely the ethics of respect of persons than utilitarianism.

Free and informed consent and compensation

Three necessities to give free and informed consent to the risks imposed by technology:

A person must not be coerced

A person must have the relative information

A person must be rational and competent enough to evaluate the information.

Lay criterion of acceptable risk:

An acceptable risk is one in which risk is freely assumed by free and informed consent, or properly compensated, and which is justly distributed.

The Government Regulator’s Approach to Risk

An acceptable risk is one in which protecting the public from harm has been weighted more heavily than benefiting the public.

Three approaches to acceptable risk

Risk Expert: wants to balance risk and benefit in a way that optimizes overall public well-being.

Layperson: wants to protect himself or herself from risk.

The government regulator: wants as much assurance as possible that the public is not being exposed to unexpected harm.

Becoming a Responsible Engineer Regarding Risk

Includes to be aware• that risk is often difficult to estimate• that there are different approaches to

the determination of acceptable risk• of the legal liabilities regarding risk.

(A more general) Principle of Acceptable RiskPeople should be protected from the harmful effects of technology, especially when the harms are not consented to or when they are unjustly distributed, accept that this protection must sometimes be balanced against (1) the need to preserve great and irreplaceable benefits and (2) the limitations on our ability to obtain informed consent. Page 168 some issues (6) that arise in applying the principle.