A Simplified Method for A Simplified Method for Analyzing Variable Lifting JobsAnalyzing Variable Lifting Jobs

Rick Goggins, CPEWashington State Department of Labor and Industries

Overview

Need for simplified analysis method

Proposed data collection and analysis method

Case study–Simplified method (Lifting Calculator)–NIOSH Lifting Equation

NIOSH Lifting Equation

Many limitations15-minute observation suggestedMeasurement errors–Horizontal distance–Frequency–Asymmetry–Coupling

Not well suited for variable (multi-task) lifting jobs

A simpler method would be nice

Simplified method

NIOSH LE Lifting CalculatorDesigned for practitioners“Serious” analysis toolRequires precise measurementsRecommend analyzing 10 to 15 lifts for variable jobs

Designed for layperson

Quick screening tool

Allows estimation

Analyze 3 lifts for variable jobs

Washington State Lifting Calculator

Based on NIOSH LE, but with Lifting Index of 1.5-2.0More discrete categories rather than continuous measurementsDoes not take into account:–Destination of lift–Distance component–Coupling component

Analyzing Multi-Task Jobs

Different weights / different locations

Analyze three lifts:

Worst-case lifts:

1. Heaviest object lifted (posture only) 2. Most awkward lift (posture only)

and

3. Most common type of lift (use frequency and duration of all lifts)

Simplified Method in Use

Data Collection– Interview–Records Review –Observation

Interview

Gain understanding of job as wholeDetermine typical work pace, objects handledDetermine factors that can change load weights, frequency of liftingFind worst case scenarios

Review Records

Sources of Data–Shipping records–Production data–Pick sheets–Work expectations

Review Records

Objective data to determine frequency and duration of lifting

Select typical and worst case lifts

Determine which lifts to observe during next phase

Observation

Representative samples of typical and worst case lifts

Determine work pace, work/rest cycles, multiple lifts

Observe/measure lifting postures

Note constraints, obstructions, storage practices

Case Study Lumberyard Order Picking

Interview Findings

Busiest time in summer

Typical busy day will fill around 25 orders

Customers occasionally help with lifting

Most common lifts are of dimensional lumber

Heaviest objects are timbers, most awkward lifts are from below racks

Lifts to Analyze

What is the most awkward lift you do? (which zone)

Records Review Findings

Handwritten sales slips from typical busy day

Number of each item lifted

Weight of each item

Total = 120 lifts per day (~ 1 hour)

DJ

Lifts to Analyze

Most common and heaviest lift

Yardman lifting distribution

0

24

6

8

1012

14

161820

17.5 18 20 22 24 25 30 32 36 40 44 47 48 50 53 54 56 58 60 65 67 90 103

150

Weight

Num

ber o

f lift

s

70

Observation

Will lift multiple items at one time (50 – 60 pounds per lift)

A lot of storage below knee level

Lifting in short bursts @ 2 to 3 lifts per minute

1 hour per day

Lifts to Analyze

Most common lift:– 47 pounds– Below knees– Mid distance– Twisting < 45

degrees– Frequency = 2 to 3

lifts per minute– Duration = 1 hour

per day

Lifts to Analyze

Heaviest lift:• Below knees• Close distance• 90 pounds• Twisting < 45 degrees

Most awkward lift:• Below knees• Far distance• 70 pounds• Twisting > 45 degrees

Analysis ResultsWash. State Lifting Calculator

Actual weight Weight limit

Most common liftHazard 47 lbs. 45 lbs.

Heaviest liftHazard 90 lbs. 70 lbs.

Most awkward liftHazard 70 lbs. 30 lbs.

Analysis ResultsNIOSH Lifting Equation

HM VM DM FM AM CM

Most common liftRWL = 22 lbs.

LI = 2.2

0.63 0.93 0.97 0.91 0.94

1.0 1.0

0.92

0.901.0

1.0 0.840.50

0.90

Heaviest liftRWL = 38 lbs.

LI = 2.3

0.93 0.90

Most awkward liftRWL = 15 lbs.

LI = 4.6

0.87 0.90

CLI = 4.8

Analysis Results

Lifting Calculator resulted in weight limits about 2x those of NIOSH LEBoth methods identified need for changesBoth methods would result in same priority for changes

Potential Solutions

BetterOK

Better Best

Post Solution Analysis ResultsWash. State Lifting Calculator

Actual weight Weight limit

Most common liftAcceptable 35 lbs.

(per person)70 lbs.

Heaviest liftAcceptable 45 lbs.

(per person)90 lbs.

Most awkward liftAcceptable 70 lbs. 90 lbs.

Post Solution Analysis ResultsNIOSH Lifting Equation

HM VM DM FM AM CM

Most common liftRWL = 39 lbs.

LI = 0.8

1.0 0.93 1.0 0.91 1.0

1.0 1.0

1.0

1.01.0

1.0 1.00.83

0.90

Heaviest liftRWL = 44 lbs.

LI = 1.0

0.96 0.90

Most awkward liftRWL = 38 lbs.

LI = 1.8

1.0 0.90

CLI = 1.9

Conclusions

Simplified method requires pre-screening, less observation

Looking at combination of typical and worst case lifts gives good indication of hazards

NIOSH LE and Lifting Calculator give similar results when goal is analysis for change

Thank You