Fundamental Concepts

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Fundamental Concepts Terms

• IENG 331
• Safety Engineering

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Why Safety?

• Read Chapter 3!
• Humanitarian Reasons
• Regulatory Reasons
• Economic Reasons

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What is an Accident?

• An event that is not expected or intended
• Could cause
• injury
• loss
• Implies chance

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Fundamental Accident Causes

• Unsafe Acts
• Unsafe Conditions
• Both
• Not necessarily a chance event

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Types of Losses

• Injury
• illness
• disease
• death
• damage to property, equipment, materials
• cost of replacement
• legal medical services

• Loss of time, production, sales
• time to complete forms
• recordkeeping
• investigations
• cleanup
• hospitalization, rehab
• public image damage

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Losses Direct vs Indirect Costs

• Direct (Obvious)
• medical expenses, WC, repair or replace damages
• Indirect (Not Obvious)
• 41 Ratio
• Iceberg Theory
• See Table 3-1

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Unsafe Acts vs Unsafe Conditions

• Heinrich analyzed 75,000 accidents
• 88 10 2 ratio
• 88 unsafe acts
• 10 unsafe conditions
• 2 unpreventable causes
• Engineers can attack unsafe conditions
• Must understand human behavior and management
  principles to attack unsafe acts

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Accident - Injury Relationship

• Heinrichs 300 29 1 ratio
• For 330 accidents
• 300 result in no injury
• 29 produce minor injuries
• 1 produces major, lost-time injury
• Opportunities to improve are great
• Many accidents are rehearsed many times

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Accident - Costs Relationship

• Pareto Relationship
• 80 - 20 rule
• 80 of the costs are related to 20 of the
  injuries
• for example, low back lifting injuries represent
  20 of all accidents, but represent 80 of the
  costs
• if you can manage and control that 20 of
  accidents, you can control 80 of the costs
• Figure 3-1 shows 50 of the costs are related to
  2 of the injuries
• the powerful few

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Terms

• Safety being relatively free from harm, danger,
  damage, injury
• Risk measure of both frequency and severity of
  hazards
• Hazard unsafe condition, the potential for an
  activity or condition to produce harm
• Safety Engineering application of engineering
  principles to the recognition and control of
  hazards

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Accident Theories

• Domino Theory
• Energy Theory
• Single Factor Theories
• Multiple Factor Theories

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Domino Theory (Heinrich)

• Injury is caused by
• Accidents which are caused by
• Unsafe acts or conditions which are caused by
• Undesirable traits (e.g., recklessness,
  nervousness, temper, lack of knowledge, unsafe
  practices) which are caused by
• Social environment

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Domino Theory Cont.

• Stop the sequence by removing or controlling
  contributing factors
• Strong emphasis is placed on the middle domino
  unsafe acts or conditions

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Energy Theory (Haddon)

• Accidents Injuries involve the transfer of
  energy, e.g., fires, vehicle accidents,
  projectiles, etc.
• Transfer of energy from a potential to
  kinetic
• Attack problems in parallel rather than serial
  (as is presumed in Domino Theory)

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Energy Theory Cont.10 Strategies to Prevent or
Reduce

• 1. Prevent the marshalling of energy.
• - dont produce the energy
• - dont let kids climb above floor level
• - dont produce gun powder
• 2. Reduce the amount of energy marshalled.
• - keep vehicle speeds down
• - reduce chemical concentrations
• - dont let kids climb above 3

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3. Prevent the release of energy - elevator
brakes 4. Modify the rate at which energy is
released from its source or modify the spatial
distribution of the released energy. - reduce
the slope on roadways 5. Separate in space or
time the energy being released from the structure
that can be damaged or the human who can be
injured. - separate pedestrians from vehicles
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6. Separate the energy being released from a
structure or person that can suffer loss by
interposing a barrier. - safety glasses, highway
median barriers 7. Modify the surfaces of
structures that come into contact with people or
other structure. - rounded corners, larger
surface areas for tool handles 8. Strengthen the
structure or person susceptible to damage. -fire
or earthquake resistant structures, training,
vaccinations
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9. Detect damage quickly and counter its
continuation or extension. - sprinklers that
detect heat - tire tread wear bands 10. During
the period following damage and return to normal
conditions, take measures to restore a stable
condition. - rehab an injured worker - repair a
damaged vehicle
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Single Factor Theories

• Assumes that when one finds a cause, there is
  nothing more to find out.
• Weak theory, there can be so much more to learn!

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Multiple Factor Theories

• Accidents are caused by many factors working
  together
• The theory and the analysis is more complex, but
  more realistic than Single Factor Theory
• Consider the Four Ms
• management, man, media, machine
• And their interactions

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Preventative Strategies

• Proactive vs. Reactive
• Frequency strategies
• Severity strategies
• Cost strategies
• Combinations
• Three Es of Safety engineering, education,
  enforcement

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How Safe is Safe Enough?

• Can absolute safety be achieved?
• Remember the concept of risk.
• What is acceptably safe?

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HW3 Chapter Three

• Review Questions (p. 24-25)
• 2, 5, 8, 11, 14, 17, 20
• 15 points
• Due 9/15 (beginning of class)