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IE 419 Work Design:

Productivity and Safety

Dr. Andris Freivalds

Class #21

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Basics of Accident Prevention(Heinrich, Petersen, Roos – Industrial Accident Prevention)

• Accident Prevention – direct control of workers, machines, environment to prevent accidents

• Safety Management - long range planning, education, training to prevent accidents

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Accident Prevention Process

Identify Problem

Collect Data

Analyze Data

Select Remedy

Apply Remedy

Monitor

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Domino Theory (Identify Problem)

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Ex. #1 - Domino Theory

Sparks from grinder ignite nearby gasoline causing operator to be burned.

• Lack of Control• Basic Causes• Immediate Causes• Accident• Injury

Multiple causation!

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Accident Causation

Unsafe Acts Unsafe Conditions

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Accident “Iceberg”

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3 E’s of Accident Prevention

• Engineering – redesign of job/workplace

• Education – training

• Enforcement – discipline, rules

Accident Causation Models →

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Life Change Unit Theory

• Accident probability is situational

• Overload taxes person’s capacity

• Leads to accidents (or illness)

• >300 → 79% in 2 yrs• >200 → 51% in 2 yrs• >150 → 37% in 2 yrs

Rank Life Event Units

1 Death of spouse

100

2 Divorce 73

4 Jail term 63

6 Injury 53

27 End school 26

41 Vacation 13

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Motivation-Reward Satisfaction Model(Identify Problem)

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Behavioral Based Training

• ABC approach

• A – antecedents

• B – behavior

• C - consequences

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Collect Data – Analyze Data

• Systematic approach

• Who, what, where, when, how, why

• Inspection– Job/methods analysis

– Worksite analysis

– Job Safety Analysis (JSA)

– (Look beyond direct causes!!)

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Job Safety Analysis (JSA)(Job Hazard Analysis, Methods Safety Analysis,

Critical Incident Technique, Failure Mode and Effects Analysis (FMEA), Hazard and Operability Study (HAZOP))

1) Break down job into elements

2) List them in sequential order

3) Examine them critically

4) Focus on:• Worker• Method• Machine• Material

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Ex. #2 - JSAScenario: Two inspectors smashed their toes

when a stack of armor plate (36x24x⅜ in), standing on end against workbench, slid to the floor. They were stacked there because of insufficient room to leave them on delivery pallet, towed from Receiving. Since each piece needed to Rockwell tested, the inspectors stacked the plates on end rather than laying them flat on the floor, which would require later lifting (NIOSH!!). Similar accidents had occurred earlier, but without injuries.

Typical Solution:

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Ex. #2 – JSA con’t (Old Method)

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Ex. #2 – JSA con’t (New Method)

Recommendation: Adjustable, powered transporter (two)

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Advantages of JSA

• Maps out all details

• Quick, simple, objective

• Compares old & new methods

• Examines effects on production

• Analyze safety before accident occurs

• Leads into Fault Tree Analysis

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Select Remedy Decision-Making Tools - Hazard Action Table

Conditions

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Ex. # 3 - Value Engineering

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Value Engineering - Safety

• Define Factors:– Effect on safety– Cost– Morale– Social/environment

• Choose Alternatives – depends • Determine Weights – judgmental• Rate each alternative by factor - relative• Resulting Value (sum of products) selects

proper alternative

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Risk Analysis – Basics

• Basic premise/approach– All risks can not be eliminated– However, can reduce potential loss– Go for max cost effectiveness

• Risk of loss increases with:– ↑ probability that hazard will occur– ↑ exposure to the hazard– ↑ consequences of hazardous event

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Risk Analysis - Procedure

• Assign numerical values to factors

• Multiply factors → overall risk score

• Risk score is a numerical value

• Good for relative comparison (not absolute)

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Likelihood Values

Expected 10

Possible 6

Unusual 3

Remote 1

~ Conceivable 0.5

~ Impossible 0.1

Exposure Values

Continuous 10

Daily 6

Weekly 3

Monthly 2

Few/year 1

Yearly 0.5

Factor Values

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Possible Consequences Value

Catastrophe (many fatalities, $108 damage) 100

Disaster (few fatalities, $107 damage) 40

Very serious (fatality?, $106 damage) 15

Serious (serious injuries, $105 damage) 7

Important (injuries, $104 damage) 3

Noticeable (first aid, $103 damage) 1

Possible Consequences

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Risk Situation Value

Very high risk, discontinue operations 400

High risk, immediate correction 200-400

Substantial risk, correction needed 70-200

Possible risk, attention needed 20-70

Risk?, perhaps acceptable < 20

Risk Score

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Ex. #4 - Risk Calculation

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Ex. #5 - Risk and Cost Effectiveness

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Apply Remedy and Monitor

• Who applies remedy– Safety specialist/engineer– Line supervisors– Workers

• Monitor effectiveness of accident prevention– Close the feedback loop– Variety of statistical

approaches

Identify Problem

Collect Data

Analyze Data

Select Remedy

Apply Remedy

Monitor

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Accident and Injury Statistics

• Incidence (frequency) rate

IR = # incidents x 200,000

# hrs exposure

• Severity rateSR = # days lost x 200,000

# hrs exposure

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Chi-Square Analysis• χ2 = ∑ (Ei – Oi)2/ Ei Ei = HixOT/HT

• M = # areas Ei = expected

• Oi = observed OT = Total observed

• Hi = hours worked in area i

• HT = total hours worked ν = m -1

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Ex. #6 - Chi-Square Analysis

χ2 = ∑ (Ei – Oi)2/ Ei

Dept. # CTD # Hours IR Ei

A 22 900,000

B 4 600,000 1.3 7.4

C 10 1,400,000 1.4 17.4

Total 36 2,900,000 2.5 36

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Red Flagging – Control Chart

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Red Flagging - Monitor