Ergonomic Control Strategies

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Ergonomic Control Strategies
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Control Strategies
Engineering Controls
Workstation Design Tool Design Process
Modification Mechanical Assist Education
Administrative Controls
Training Job Rotation Pacing Policy Job
Enlargement
Band Aid Solutions ?!?
Splints Braces
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ANTHROPOMETRY
The technology of measuring and quantifying
various human physical traits such as size,
weight, proportion, mobility and strength.
Engineering Anthropometry
The application of anthropometric data to
equipment, workplace and job design to enhance
the efficiency, safety and comfort of the
operator.
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Anthropometry
IS SPECIFICALLY USED TO

• Ensure the work area design is compatible with
  the workers body.
• Safeguard from point of contact hazards.

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Anthropometric Percentiles

• Measurements (percentiles) are provided for both
  the male and female population
• The tables show the 5th, 50th, and 95th
  percentile value for both male and female body
  dimensions

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Anthropometric Design Strategies

• DESIGN FOR THE EXTREME
• Accommodate reach for the short and fit for the
  tall.
• DESIGN FOR THE WORKER POPULATION
• If the worker population does not change, design
  the work areas to be adjustable to accommodate
  those workers
• DESIGN FOR A RANGE/ADJUSTABILITY
• Whenever possible, design a work area to include
  adjustability to accommodate the 95 male and the
  5 female neutral postures
• DONT DESIGN FOR THE AVERAGE

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Anthropometry
Design Strategies

• Design for the extreme
• Accommodate reach for the short and fit for
  the tall
• Design for the worker population
• If the worker population does not change,
  design the work areas to be adjustable

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Anthropometry
Design Strategies

• Design for a range
• Optimum adjustability is from the 5th
  percentile female to the 95th percentile male
• The proper positioning depends on the type of
  work being done
• Factor in the size of parts being worked on

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Anthropometry Exercise
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AnthropometryExercise 2
How high should the visual display be (accounting
for adjustability) to accommodate the 5th and
95th people?
VISUAL DISPLAY
123
HANDCONTROLS
How high should the control panel be (accounting
for adjustability) to accommodate the 5th and
95th people?
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Design Strategies -Work Zone
E
D
B
C
A
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Design Strategies - Lifting Zone

• Locate objects between knuckle and heart levels
• Minimize reach
• Eliminate bending
• Eliminate twisting
• Avoid high speed or acceleration

TARGET ZONE
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Design Strategies -Tool - Target
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In-Line Tool
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Design Strategies -Hand Tool Design
Common Risk Factors

• Awkward or forceful gripping
• Twisting or bending of the wrist
• Static arm postures
• Excessive tool weight
• Excessive vibration
• Repetitive triggering actions
• Heavy trigger pressure
• Mechanical stresses on the hand and fingers
• Exposing the hand and wrist to heat and cold

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Design Strategies - Hand Tool Design
Power Tools Tips Controls

• Use tool balancers
• Reorient work
• Use angled tools
• Use in-line tool for vertical work
• Use Pistol Grip for horizontal work
• Use dyna-swivel
• Use adjustable workstations
• Use 3 or 4 finger triggers
• Handles should be 4-5 long
• Utilize vibration torque dampening features
• Handle diameter 1.25-2
• Control exhaust exit point

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Design Strategies - Hand Tool Design
Triggers

• Minimal 1 long to allow for activation by 2
  fingers,
• 3 or 4 finger triggers should only be used on
  suspended tools,
• Trigger should be activated by index or middle
  finger
• Avoid thumb triggers on highly repetitive
  operations

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Design Strategies - Hand Tool Design
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Design Strategies - Hand Tool Design
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Design Strategies - Hand Tool Design
Torque

• For a pistol grip tool use reaction torque
  limiting device if torque exceeds 24 in-lb.
• For a straight or in-line power tool use
  reaction torque limiting device if torque
  exceeds 14 in-lb.
• For a right angle power tool with torque
  exceeding 442 in-lb. use an articulating arm,
  or some other positive means of reaction torque
  limiting device.

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Design Strategies -Manual Tool Dimensions
A
A
B
C
A gt 4 B (for power grips) 1.5
C 3 to 3.5
(for precision operations) .45
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Padded Handles
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Design Strategies -Manual Tools
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Design Strategies -Sit versus Stand
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Design Strategies -Sit versus Stand
FACTS ABOUT SITTING

• On average, sitting erect places 50 more
  compressive force on the spine than standing in a
  comfortable, erect posture
• Sitting in a poor posture can double the amount
  of compressive force that is placed on the spine
  when standing in a comfortable, erect posture
• Sitting reduces blood flow to back muscles

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Design Strategies -Sit versus Stand
ADVANTAGES OF STANDING

• Encourages movement and changes in posture, which
  promotes blood circulation
• Allows body weight and strength to be used more
  effectively
• Encourages the person to move the feet rather
  than twisting or leaning with the upper body

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Design Strategies -Sit versus Stand

• Work height based on work being performed
• Account for foot clearance
• Avoid Sharp edges
• Provide anti-fatigue matting

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Design Strategies -Sit versus Stand

• Work height based on work being performed
• Avoid mechanical pressure form the front of seat
• Ensure that there is enough room for knees and
  feet
• The seat should have adjustable height and lower
  back support
• Avoid sharp edges
• workstation should be height adjustable

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Footrest
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Design Strategies -Sit versus Stand
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Design Strategies -Sit versus Stand
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Design Strategies -Sit versus Stand
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Design Strategies -Sit versus Stand
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Results (Ergonomic Workstation Design)

• In nine manufacturing locations that
  incorporated ergonomic workstation design, after
  an average follow-up period of 247 days, the
  following results were seen
• The CTD incident rate (incidents per 200,000
  hours) changed from 10.0 to 1.6 an 84
  improvement.
• The days lost due to CTDs improved from 24.9 days
  per 200,000 hours worked to 16.0 a 36
  improvement.

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Results (Ergonomic Workstation Design) cont.

• In nine manufacturing locations that
  incorporated ergonomic workstation design, after
  an average follow-up period of 247 days, the
  following results were seen
• The restricted days due to CTDs improved from
  58.5 days per 200,000 hours worked to 6.4 a 61
  improvement.
• The average risk factor score for 29 affected
  tasks in the nine locations was 29.7 before the
  devices were put into place, and was 17.5
  afterwards a 43 improvement.

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Design Strategies -Push versus Pull
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Design Strategies -Push versus Pull
ADVANTAGES OF PUSHING

• Allows person to get in better alignment to use
  both hands to exert the force
• Allows entire body weight to be used more
  effectively
• Improves stability in case of slipping

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Design Strategies -Push versus Pull
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Design Strategies -Back Issues

• Minimize pushing/pulling
• Minimize load weights
• Slide objects
• Lower loads rather than lift
• Use gravity
• Avoid double handling
• Use suitable containers
• Provide comfortable hand holds
• Remove constraints/obstacles
• Avoid placing loads on the floor

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Design Strategies -Back Issues
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Design Strategies -Back Issues
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Scissor Lift
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Tilt Stand
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Desk Lifter
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Vacuum Lift
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Results (Lifting Aid, Lift Assist Devices, and
Transport Devices)

• In sixty-five manufacturing companies that
  received lift assists, aids, and/or transport
  devices, after an average follow-up period of 214
  days, the following results were seen
• The CTD incident rate (incidents per 200,000
  hours) changed from 9.8 to 4.9 a 50
  improvement.
• The days lost due to CTDs improved from 110 days
  per 200,000 hours worked to 36.2 a 70
  improvement.

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Results (Lifting Aid, Lift Assist Devices, and
Transport Devices)

• The restricted days due to CTDs improved from 102
  days per 200,000 hours worked to 39.5 a 61
  improvement.
• The turnover rate (per 200,000 hours worked)
  changed from 53.2 to 44.5 a 16 improvement.
• The average risk factor score for 120 affected
  tasks in the sixty-five companies was 33 before
  the devices were put into place, and was 19
  afterwards a 42 improvement.

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Lift Gate
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CTD incident and lost days rates in construction
n 30, Incident 32, Lost days 82 improvements
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Design Strategies -Environmental Considerations

• Work space
• Illumination
• Glare
• Temperature
• Walking Surfaces

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Administrative Actions

• Administrative controls reduce the exposure to
  the hazard, but dont usually eliminate it.
• Training
• Job Rotation
• Pacing
• Methods, Policy, Guidelines
• Job Enlargement

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Administrative ActionsTraining

• Awareness Training
• Supervisor Training
• Team Member Training
• Upper Management Training
• Engineering/Maintenance Training

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Administrative ActionsJob Rotation

• Rotate to a job with completely different risk
  factors
• Rotate frequently
• Rotation schedule should be well defined and
  enforced

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Administrative ActionsPacing

• Method of minimizing exposure by re-balancing the
  of production
• Not popular because it usually reduces production

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Administrative ActionsMethods, Policy,Guidelines

• Involves formal definition of task
• Explicitly enforces best practices for the task
• Having everyone trained by select individuals
  helps consistency

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Administrative ActionsMethods, Policy,Guidelines
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Administrative ActionsMethods, Policy,Guidelines
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Administrative ActionsJob Enlargement

• Increase the number of tasks performed by the
  employee
• Causes the employee to perform the high risk
  factor task less frequently

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Controls Exercise
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Elevated Pallet
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Stairclimber
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Ramp
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Spring Loaded Laundry Carts
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Height Adjustable Cart
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Office Workstation
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Pallet Breaker
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Before - After
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Crane
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Conveyors
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Cart Redesign
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Before - After
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Barrel dumper
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Dolly with foot pedal
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Automated bleachers
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Moveable ladder
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Mopping floors
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Ceiling lifts
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MSD Rate by Intervention Type
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Comparison with National data (BLS, 2003)

• BLS back injury incidence rate in nursing homes
  and personal care facilities
• In 1998, 1.84
• In 2002, 1.53
• 17 reduction in 5 years
• Due to staggered start, we cannot make a direct
  comparison.
• Our back injury incidence rate
• Baseline, 3.91
• Follow-up, 2.19
• 44 reduction

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Automatic Feeding
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Height Adjustable Cart
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Counterbalanced staple gun
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Before - After
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Before - After