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Mastering the Toolsof the
Ergonomics TradeDavid Alexander, PE, CPE
Auburn Engineers, Inc.
© 2012 w w w . e r g o p a g e . c o m
About Dave Alexander . . . Entrepreneur, Pioneer, Author, Inventor
Auburn Engineers, Inc.• Founder, President• Since 1987• Consultant to industry &
government
Eastman Kodak• 13 years experience• Ergonomics• Management Consulting
Registered Professional Engineer
Certified Professional Ergonomist
Peer Recognition• IIE - Fellow 1990 , Ergonomics
Division Award, 1986• HFES - IE Technical Group
Award, 1993
Texts• Industrial Ergonomics: A
Practitioner’s Guide• The Practice and Management
of Industrial Ergonomics• Industrial Ergonomics: Case
Studies• Ergonomics Design Guidelines• Applied Ergonomics - Case
Studies Volumes 1, 2 & 3
Software & Technology• eTools Shop, eTools Office,
eTools Design
Patent Holder• Pivotable Pommel• Culinary Decorator
Applied Ergonomics Conference Series
• Founder and Chair
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KELLWOOD
THANKS TO OUR CLIENTS…
who permit us to push the envelope of ergonomics around the world.
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Mastering the Tools of theErgonomics Trade
Presentation Objective: To provide an overview of the tools available to an ergonomics practitioner for the evaluation of work
Topics:1. How much is too much?2. What tools are available?3. Using some common tools4. Freeware5. The next generation of tools6. Questions/Answers
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What Is an Ergonomics Job Evaluation?Look at these workers. Will their work result in injury?
Credit: “Grape Pickers”, Lew Keller, US Post Office, St. Helena, CA (Works Project Administration Art Project 1932)
Lifting, carrying, use of hand tools, stooped postures and other issues will result in acute or overuse injuries.
More importantly, can we predict which injuries will occur, how serious they might be, and at what frequency?
Note that there are other safety and health issues as well.
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Tools of the Ergonomics TradeAIHA Ergonomic
Assessment ToolkitACGIH TLVsCTD Risk AssessmentMetabolic RateGM-UAW Ergonomic ChecklistLiberty MutualNIOSH Lifting GuideOccupational Repetitive ActionOSHA Screening/VDT ChecklistsPLIBELRodger’s Muscle Fatigue
AssessmentStrain IndexUtah Back Compressive ForceWashington State Caution &
Hazard Zones, Lifting Calculator
University of South Florida Ergonomics Analysis Methods
AnthropometryReach EnvelopePercentilesStatic Work AnalysisEstimation of Metabolic WorkDynamic Work AnalysisWashington Department of Labor &
IndustriesRapid Upper Limb Assessment RULARapid Entire Body Assessment REBARodger’s Muscle Fatigue AssessmentWhole Body VibrationACGIH TLVsLiberty Mutual Manual Materials
Handling ToolsUtah Back Compressive ForceNIOSH Lifting Guide
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Tools of the Ergonomics Trade
AIHA Ergonomic Assessment Toolkit
http://www.aiha.org/insideaiha/volunteergroups/Ergonomics/Documents/ECToolkit.pdf
University of South Florida Ergonomics Analysis Methods
http://personal.health.usf.edu/tbernard/ergotools/index.html
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Tools of the Ergonomics Trade
• Size• Special
PopulationsAnthropometricAnthropometric
• Force• Repetition• Posture
MusculoskeletalMusculoskeletal
• Fatigue• EndurancePhysiologicalPhysiological
• Light• SoundSensorySensory
• Heat• VibrationEnvironmentalEnvironmental
• Upper Extremities
• Low Back
Shop or Office?
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Some Common Ergonomics Job Evaluation Tools
Borg Scale for Rating of Perceived Exertion
Lifting Index
Energy Expenditure Prediction Program
3D Static Strength Prediction Program
Ovako Working Posture Analysis - OWAS
Rapid Upper Limb Assessment - RULA
Rapid Entire Body Assessment - REBA
ACGIH TLV for Hand Activity
Revised NIOSH Lifting Equation
Liberty Mutual Tables for Lifting, Carrying, Pushing & PullingWISHA Checklists
Qualitative Quantitative
Specialized: single body part
Comprehensive: many risk factors; many body parts
OSHA Checklists
Strain Index
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Practitioner’s Dilemma:What Tool to Use?How Many to Use?
Rapid Upper Limb Assessment RULA
Rapid Entire Body Assessment REBA
Revised NIOSH Lifting Equation
Liberty Mutual Tables for Lifting, Carrying,
Pushing & Pulling
WISHA Checklist
Strain Index
Screening:Qualitative
Analysis:Quantitative
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From the Grape Pickers:What do our ergonomics tools tell us?
Rapid Upper Limb Assessment RULA
Rapid Entire Body Assessment REBA
Revised NIOSH Lifting Equation
Liberty Mutual Tablesfor Lifting, Carrying,
Pushing & Pulling
WISHA Checklist
Strain Index
Screening:Qualitative
Analysis:Quantitative
Investigate
= 32.6
> 7
= 15.7
Hazard
Very High Risk
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Measuring Ergonomics Risk Factors – 2nd Generation Tools
Qualitative ToolsWISHA Screening ToolVisual Observations
Semi-Quantitative ToolsREBA & RULAACGIH TLV for Hand/Arm VibrationLiberty Mutual MMH TablesRogers Muscle Fatigue Assessment
QuantitativeMoore-Garg Strain IndexNIOSH Lifting GuidelineAnthropometry Tables
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(WISHA)Washington Industrial Safety and
Health ActQualitative
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WISHA - Awkward Posture
No
No
No
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WISHA - Awkward Posture
X
X
X
(Not shown in graphic) Picking grapes requires bending knees to pick up box from ground
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WISHA - Hand Force -- Pinch
X
X(Not shown in graphic) Picking grapes requires pinching, often in bent wrist postures
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WISHA - Hand Force -- Grasp
Carrying containers of grapes
X
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WISHA - Highly Repetitive Motion
X
Not applicable
Cutting grape stems
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WISHA - Repeated Impact
Not Applicable
Not Applicable
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WISHA - Lifting Analysis
45
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Rapid Upper Limb Assessment (RULA)
Semi-Quantitative
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RULA
Uses body posture diagrams and three scoring tables to quantify risk factors
ConsidersBody Part Postures• Arm and Wrist• Neck, Trunk & Leg
Muscle UseForce Demands
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RULA - Rapid UpperLimb Assessment
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RULA -- Total Grand ScoreStep 5:a) Cross reference Score C + Score D b) Use Table C to look up Grand Score
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RULA -- Total Grand Score
A
B
Upper arm
Lower arm
Wrist
Wrist twist
Neck
Trunk
Legs
Muscle Force Score C
Muscle Force Score D
Grand ScoreUse Table C
Use Table B Posture Score B
Use Table A Posture Score A
Step 5:a) Cross reference Score C + Score D b) Use Table C to look up Grand Score
2
1
3
1
3
8
5
4
2
0
1
3
3
6
12
7
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RULA -- Action Levels
Level 1 (Score of 1 or 2)• Posture acceptable if not maintained
or repeated for long periodsLevel 2 (Score of 3 or 4)
• Further investigation needed; changes may be required
Level 3 (Score of 5 or 6)• Investigation & changes required soon
Level 4 (Score of ≥7)• Investigation & changes required immediately
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Rapid Entire Body Assessment (REBA)
Semi-Quantitative
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REBA - Rapid Entire Body Assessment
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REBA
Uses body posture diagrams and three scoring tables to quantify risk factors
ConsidersBody Part Postures• Neck, Trunk & Leg• Arm and Wrist
Muscle UseForce Demands
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Activity Score - REBA
A
B
Neck
Trunk
Leg
Upper Arm
Lower Arm
Wrist
Force/Load Score A
Score C
Coupling Score B
Activity
Final REBA Score
Use Table C
Use Table B Posture Score B
Use Table A Posture Score A
Step 1:a) Score Group A: neck, trunk, leg; look up in Table A, add force load to
get score Ab) Score Group B: upper arm, lower arm, wrist; look up in Table B
total in Posture Score B
3
3
37 2 9
1
1
1
1 1 2
29
11
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REBA -- Action Levels
12 or 34 to 7
8 to 10
11+
Negligible riskLow risk, change may be neededMedium risk, further investigation,
change soonHigh risk, investigate and implement
changeVery high risk, implement change
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RULA & REBA -- Summary
Simple surveys that target upper limb and/or entire body MSD risks
Good for screening large numbers of employees quickly
Identifies if further analysis is needed (low thresholds – most tasks are “investigate”)
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Manual Handling Tasks
NIOSH Lifting Guideline (Quantitative)Liberty Mutual MMH Tables (Semi-Quantitative)
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Chosing The Right Model
Biomechanical
Physiological
Psychophysical
Load/Force
Frequency
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NIOSH Lifting Guidelines
THE 1991 NIOSH EQUATION FOR THEDESIGN AND EVALUATION OF
MANUAL LIFTING TASKS
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H = horizontal distance from mid-point between ankles to hands.
V = vertical distance ofhands above floor.
D = vertical travel distance
A = angulardisplacementof load from sagittalplane (i.e. twisting).
F = average number oflifts during 15 min.
C = quality of hand to object coupling.
Weight = 45 lb.
H = 9 inches
V = 30 inches
D = 40 inches
A = 30 degrees
F = 1 lift/5 min.
Dur = 10 hours
C = Fair (small)
35”
9”
+10” when standing
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X X X X X = Lbs.RWL = 51 X
RWLLI =
Object Weight (L)= =
Calculations
RWL = 51 x HM x VM x DM x AM x FM x CM24” 15” 40” 0 ˚ Poor829 lbs 3
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Who Is At Risk?
LI = 1.0 LI = 2.0 LI = 3.0
DESIGN OBJECTIVE
RWLLI = Object Weight
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eLIFThttp://www.ergopage.com/Freeware
(Visitors from 165 countries last year)
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eRULAhttp://www.ergopage.com/Freeware
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eREBAhttp://www.ergopage.com/Freeware
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Summary & Closing
There are many ergonomics job evaluation tools.
Knowledge and skills are required for their use.Interpretation is important. Different tools may
provide conflicting results.Using the wrong tool can provide incorrect
answers.
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A 3rd Generation of Ergonomics Tools Is Emerging
A set of tools that work easily together.Screening and evaluation use similar data.The output is visual: Red, Yellow, GreenAn “non-expert” user can deliver quality
results.Analysis leads directly to targeted, specific
solutions.
An analogy:1st Generation – Bulky satellite telephone2nd Generation – Cellular telephone3rd Generation – Smart phone
© 2012 w w w . e r g o p a g e . c o m
Mastering the Toolsof the
Ergonomics TradeQuestions/Answers
