Fundamental Concepts & Terms

1
Fundamental Concepts Terms

• IENG 331
• Safety Engineering

2
Why Safety?

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

3
What is an Accident?

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

4
Fundamental Accident Causes

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

5
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

6
Losses Direct vs. Indirect Costs

• Direct (Obvious)
• medical expenses, WC, repair or replace damages
• Indirect (Not Obvious)
• 41 Ratio (Iceberg Theory)
• Injured workers wages, lost supervisory time,
  co-workers lost time during emergency, damaged
  equipment, ruined product, overtime for
  production to catch back up, learning curve for
  replacement worker, clerical costs, payments made
  to injured under benefits program

7
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

8
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

9
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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Pareto Analysis The Vital 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

12
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

14
Domino Theory Cont.

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

15
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
20
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!

21
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

22
Preventative Strategies

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

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Three Lines of Defense

• Engineering Controls
• Administrative Controls
• Personal Protective Equipment

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Safety Factors

• Since there is a chance element in safety, we can
  improve our chances by implementing a safety
  factor
• Scaffolding 41
• Designed to withstand 4 times the intended load
• Overhead crane hoists 51
• Scaffold ropes 61
• Why not use 101 as a standard??
• Beware when using field tables or computer
  programs. Are the safety factors applied or not??

25
Fail-Safe Principles

• General fail-safe principle
• The resulting status of a system, in event of
  failure of one of its components, shall be in a
  safe mode.
• Read Case Studies 3.5 and 3.6
• Fail-safe principle of redundancy
• A critically important function of a system,
  subsystem, or components can be preserved by
  alternative parallel or standby units.
• Principle of worst case
• The design of a system should consider the worst
  situation to which it may be subjected in use.
• Murphys Law If anything can go wrong, it will.

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Engineering Pitfalls

• False sense of security in technology
• Read Case Study 3.7
• Human error is involved heavily
• Recommendation for Reading
• Set Phasers on Stun And Other True Tales of
  Design, Technology, and Human Error. Steven
  Casey. Aegean Publishing Company, Santa Barbara,
  CA. 1993. ISBN 0-9636178-7-7

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How Safe is Safe Enough?

• Can absolute safety be achieved?
• Remember the concept of risk.
• What is acceptably safe?
• Remember the Risk Assessment Matrix Severity vs
  Frequency

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HW3A Chapter Three

• Review Questions (p. 24-25)
• 3, 6, 9, 12, 15, 18, 21
• 15 points
• Due 9/19 (beginning of class)

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HW3B Hazard Awareness Advisor

• Go to www.osha.gov
• Select e-tools
• Go to Expert Advisors
• Select Hazard Awareness and download it to your
  computer
• Run this expert system to evaluate your
  workplace or someplace you have worked (or
  someplace you want to work).
• Write a one page memo that describes what you
  have learned from this exercise. I especially
  want to know if youve learned of some new
  workplace hazards. Do you think this is a useful
  tool for industry?
• 30 points, due asap