Home Uncategorized Advanced Ergonomics

Uncategorized

Advanced Ergonomics

This assignment is designed to provide an opportunity to demonstrate your knowledge of the ergonomic assessment process. Specifically, you will be conducting an ergonomic assessment of a videotaped task and identifying opportunities to improve the task using the concepts presented in your Unit III–VII Lessons.

Click

here

to access the video. Please note that this video contains audio.

You are required to develop a three-page written report, which must include each of the following elements:

A task description must address the work environment, work layout, tools, and equipment.
Include identification of musculoskeletal disorder (MSD) risk factors (you must include at least three risk factors) with a brief description of the risk factors, and use one of the evaluation tools (e.g., rapid upper limb assessment [RULA], rapid entire body assessment [REBA], checklist, National Institute of Occupational Safety and Health [NIOSH] lift equation) presented in your Unit VII Lesson to evaluate the task. A copy of your completed assessment tool must be included with your report.
Provide the potential for an MSD injury (quantification of risk). Note that, the exact weight of the logs and the total amount of time devoted to complete the task are unknown. If you have a need to use any information not provided, please make arbitrary choices, and provide the reason why this information might be important for the risk’s assessment.
A brief discussion of potential MSD injuries that could result from exposure to the risk factors must be included.
Recommendations for controlling the risk factors associated with the task using the hierarchy of controls. You must include at least one of each of the controls—engineering control, administrative control, and personal protective equipment (PPE).

You are encouraged to revisit the unit lesson for explanations of the tools, and below are copies of the tools and checklists. You may use one of the provided checklists or research your own. You must include the completed tool within an appendix.

Lifting/Lowering Tasks

Click here to access the Washington Industrial Safety and Health Act (WISHA) Lifting Equation.
Click here to access the NIOSH Lifting Equation.

Upper Body Posture

Click here to access the Rapid Upper Limb Assessment tool.

Entire Body Posture

Click here to access the Rapid Entire Body Assessment tool.
Click here to access the Body Map Questionnaire.
Click here to access the WISHA Caution Zone Checklist.
Click here to access the WISHA Hazard Zone Checklist.

Pushing/Pulling: Snook Tables

Click here to access the Snook tables.

Hand-Arm Vibration

Click here to access the Hand-Arm Vibration Calculator.

Your completed project must include a minimum of two outside sources, one of which must be from the CSU Online Library. The three-page written report length requirement excludes the title and references pages. You must also include your completed assessment tool in an appendix section of your report. You may also include graphics to illustrate your design recommendations.

Acknowledgements
Foreword
Table of Contents
List of Figures
List of Tables
Introduction
1. The Revised Lifting Equation

1.1 Definition of Terms
1.2 Lifting Task Limitations
1.3 The Equation and its Function
1.4 The Lifting Index

2. Procedures for Analyzing Lifting Jobs

2.1 Options
2.2 Collect Data (Step 1)
2.3 Single-Task Assessment (Step 2)
2.4 Multi-Task Procedure

3. Example Problems

3.1 How to Use the Example Problems
3.2 Jobs Performed a Few Times Per Shift
3.3 Single Task, Performed Repetitively
3.4 Repetitive Multi-Task, Short-Duration
3.5 Repetitive Multi-Task, Long Duration

Glossary
References
Appendix I

RULA Employee Assessment Worksheet

Original Worksheet Developed by Dr. Alan Hedge. Based on RULA: a survey method for the investigation of work-related upper limb disorders, McAtamney & Corlett, Applied Ergonomics 1993, 24(2), 91-99

A. Arm and Wrist Analysis

Step 1: Locate Upper Arm Position:

‘

Step 1a: Adjust…
If shoulder is raised: +1
If upper arm is abducted: +1
If arm is supported or person is leaning: -1

Step 2: Locate Lower Arm Position:

Step 2a: Adjust…
If either arm is working across midline or out to side of body:

Add +1

Step 3: Locate Wrist Position:

Step 3a: Adjust…
If wrist is bent from midline: Add +1

Step 4: Wrist Twist:
If wrist is twisted in mid-range: +1
If wrist is at or near end of range: +2

Step 5: Look-up Posture Score in Table A:
Using values from steps 1-4 above, locate score in
Table A

Step 6: Add

Muscle Use Score

If posture mainly static (i.e. held>10 minutes),
Or if action repeated occurs 4X per minute: +1

Step 7: Add Force/Load Score
If load < .4.4 lbs. (intermittent): +0 If load 4.4 to 22 lbs. (intermittent): +1 If load 4.4 to 22 lbs. (static or repeated): +2 If more than 22 lbs. or repeated or shocks: +3

Step 8: Find Row in Table C
Add values from steps 5-7 to obtain
Wrist and Arm Score. Find row in Table C.

B. Neck, Trunk and Leg Analysis

Step 9: Locate Neck Position:

Step 9a: Adjust…
If neck is twisted: +1
If neck is side bending: +1

Step 10: Locate Trunk Position:

Step 10a: Adjust…
If trunk is twisted: +1
If trunk is side bending: +1

Step 11: Legs:
If legs and feet are supported: +1
If not: +2

Step 12: Look-up Posture Score in Table B:
Using values from steps 9-11 above,
locate score in Table B

Step 13: Add Muscle Use Score
If posture mainly static (i.e. held>10 minutes),
Or if action repeated occurs 4X per minute: +1

Step 14: Add Force/Load Score
If load < .4.4 lbs. (intermittent): +0 If load 4.4 to 22 lbs. (intermittent): +1 If load 4.4 to 22 lbs. (static or repeated): +2 If more than 22 lbs. or repeated or shocks: +3

Step 15: Find Column in Table C
Add values from steps 12-14 to obtain
Neck, Trunk and Leg Score. Find Column in Table C.

Upper Arm Score

Lower Arm Score

Wrist ScoreWrist Twist Score

Posture Score A

Muscle Use Score

Force / Load Score

Wrist & Arm Score

Neck Score

Trunk Score

Leg Score

Posture B Score

Muscle Use Score
Force / Load Score

Neck, Trunk, Leg Score

Scores

+
=
+

+Scoring: (final score from Table C)
1-2 = acceptable posture
3-4 = further investigation, change may be needed
5-6 = further investigation, change soon
7 = investigate and implement change

RULA Score

Task Name: Date:

+1 +2 +2

+1
+2 +3

Add +1

+1 +2 +3

+1 +2
+3

CautionZone Checklist Use one sheet for each position evaluated.

Movements or postures that are a regular and
foreseeable part of the job, occurring more
than one day per week, and more frequently
than one week per year.

If done in this
job position

the box

Job Position
evaluated:

Date:

No. of employees
in these jobs?

Awkward Posture

Comments/Observations

1. Working with the hand(s)
above the head, or the elbow(s)
above the shoulders more than
2 hours total per day.

2. Working with the neck or
back bent more than 30
degrees (without support and
without the ability to vary
posture) more than 2 hours
total per day.

3. Squatting more than 2
hours total per day. !

4. Kneeling more than 2 hours
total per day. !

High Hand Force Comments/Observations

5. Pinching an unsupported
object(s) weighing 2 or more
pounds per hand, or pinching
with a force of 4 or more
pounds per hand, more than 2
hours total per day (comparable
to pinching half a ream of
paper).

6. Gripping an unsupported
objects(s) weighing 10 or more
pounds per hand, or gripping
with a force of 10 or more
pounds per hand, more than 2
hours total per day (comparable
to clamping light duty
automotive jumper cables onto
a battery).

Highly Repetitive Motion Comments/Observations
7. Repeating the same motion
with the neck, shoulders,
elbows, wrists, or hands
(excluding keying activities)
with little or no variation every
few seconds, more than 2
hours total per day.

!
8. Performing intensive keying
more than 4 hours total per
day. !

Repeated Impact Comments/Observations
9. Using the hand (heel/base
of palm) or knee as a hammer
more than 10 times per hour,
more than 2 hours total per
day.

!
Heavy, Frequent or Awkward Lifting (A simple scale
can be used to determine the weight of materials) Comments/Observations

10. Lifting object weighing
more than 70 pounds once per
day or more than 55 pounds
more than 10 times per day.

!
11. Lifting objects weighing
more than 10 pounds if done
more than twice per minute,
more than 2 hours total per
day.

!
12. Lifting objects weighing
more than 25 pounds above the
shoulders, below the knees or
at arms length more than 25
times per day.

!
Moderate to High Hand- Arm Vibration
(Closely estimate or obtain the vibration value of the tool in use)

Comments/Observations

13. Using impact wrenches,
carpet strippers, chain saws,
percussive tools (jack
hammers, scalers, riveting or
chipping hammers) or other
tools that typically have high
vibration levels, more than 30
minutes total per day.

14. Using grinders, sanders,
jigsaws or other hand tools that
typically have moderate
vibration levels more than 2
hours total per day.

Manual Handling Guidelines: Using Liberty Mutual Tables

Tables for evaluating lifting, lowering, pushing, pulling, and
carrying tasks.

Since the late 1970s, Liberty Mutual has been analyzing and evaluating lifting, lowering,
pushing, pulling, and carrying tasks using “Psychophysical Tables.” These tables are
research based using psychophysical methodology that includes measurements of
oxygen consumption, heart rate, and anthropometric characteristics. Psychophysical
tables provide important information about capability and limitations of workers and the
design of manual handling tasks to reduce low back disability.
During these studies, research subjects could either control the weight or force variable,
and the experimenter controlled all other task variables such as frequency, size, height,
distance, etc. The subject monitored his or her own feelings of exertion or fatigue,
and adjusted the weight or force of the object accordingly. Details of the experimental
designs are found in the individual papers (Ciriello and Snook 1983, Ciriello et al. 1990,
Ciriello et al. 1993).

Differentiator
The tables used by Liberty Mutual Risk Control are called Liberty Mutual Tables. They
are much different from those used in published literature. Some have referred to those
in the published literature as “Snook Tables” (Snook, 1978) or “Snook and Ciriello
Tables” (Snook and Ciriello, 1991). Liberty Mutual Tables provide the male and female
population percentages able to perform these tasks, while the published tables provided
Maximum Acceptable Weights and Forces for 10, 25, 50, 75, 90 percent of the male and
female population. CompuTask™ is an ergonomic software analysis program based, in
part, on the Liberty Mutual Tables.
Liberty Mutual Tables
The goal of the Liberty Mutual Tables (hereafter called “Tables”) is to help control costs
associated with manual handling operations. These costs can be attributed to high low-
back disability costs and reduced productivity and quality due to poor job design. These
Tables provide the user with an objective assessment of a problematic manual handling
job and the foundation on which to build a solution in the following ways:

■ By helping recognize risk factors associated with manual handling activity and,
■ Helping make good business decisions on implementing cost effective

ergonomic solutions that offer the highest degree of control.
Using these Tables effectively requires basic level training in ergonomics and
manual handling task analysis and evaluation. Users should be knowledgeable of
biomechanical, physiological, and psychophysical workload criteria (Waters, 1994)
and evaluation methods. Training should include developing an analysis strategy
and collection of basic measurements including weights, initial and sustained forces,
distances (lifting, lowering, carrying, hand distance from body) and task frequency.

Using the Tables: Population Percentage Criteria
As a general rule of thumb, designing manual tasks for greater than 75 percent of the
female work population will offer the best protection from manual handling injuries.
Studies have shown that two-thirds of low back claims from low percentage tasks (tasks
capable of being performed by a small percentage of the population) can be prevented
if the tasks are designed to accommodate at least 75 percent of the female work
population (Snook et al., 1978). Tasks having population percentages of less than 10
percent should be prioritized for task redesign.

RC 5812

Risk Control from Liberty Mutual Insurance

With certain industries and jobs, however, it is very difficult to design jobs that can be
performed by 75 percent of the female work population. The Tables can be used to
perform what-if scenarios of various ergonomic interventions to help determine the most
cost effective and practical solution that offers the highest degree of control.
The Tables are self-explanatory and easy to use. The following is an example.
Suppose you want to find the female population percentage for lifting tote pans. Your
measurements show the following:

■ Tote pan weight of 29 lbs.(Object Weight)
■ Hand distance of 7 in. (Hand Distance Away from Body)
■ An initial hand height of 30 in. (Hand Height at Start)
■ A final hand height of 50 in. (Hand Height at End)
■ Pans are lifted once every 5 min. (Task Frequency)

The first step is to find the correct table. Since this is a lifting task ending between
knuckle and shoulder height (≥28” and ≤53”) and you are looking for female population
percentage, go to Table 2F. Using the object weight of 29 lbs. to select the row, and
hand distance of 7 in. to select the column, locate the data in the large cell as shown
below.
Since lifting Distance is 20 in. and frequency is once every 5 minutes, this task is
acceptable to 60% of the female work population.

Since measurements seldom correspond exactly to the data points used in the tables, it
will often be necessary to estimate the population percentage. For example, if the object
weighed 30 lbs., it would fall between the 29 lb. cell as shown above and the 32 lb. cell.
Interpolation gives a population percentage of 55.
Hand Distance
Determining hand distance is one dimension that can be confusing. Hand distance is the
distance from the front of the body to the hands. Note: This is a different measurement
from the one used for the NIOSH model. Hand distance will normally be half the width of
the object that is being handled, unless the object is purposely held away from the body.
Pushing and Pulling Tasks
For pushing and pulling tasks, you will need to obtain a spring scale, a load cell, or other
force measurement device and enter the initial force, in pounds, that is needed to start
the object moving. Take several measurements and enter the highest value particularly
when floor or wheel conditions are poor.
For pushing tasks, if you only have a spring scale device, you can measure the force by
pulling. However, while the effect on the worker may be different between a push and
pull, the measured force will be the same. Also, obtain the sustained force measurement
to keep the object moving. Take all measurements at an acceleration representative of
the task as performed in the actual operating environment.

RC 5812 2

Frequency
We define frequency as the average time between handling individual objects.
Frequency can be confusing when more than one task component is present. For
example, lifting an object, carrying it a distance, and putting it back down. In our
example, if objects are lifted, carried, and lowered within a job cycle time of 30 seconds,
the frequency would be 30 seconds for the lift, 30 seconds for the carry, and 30 seconds
for the lower.

Important Considerations
A word of caution about using the Tables. Do not evaluate tasks based solely on
population percentages. Other important considerations include the following:

■ Injuries: Any job that is producing injuries is a good candidate for redesign.
■ Bending: Any task that begins or ends with the hands below knuckle

height presents some degree of risk. The deeper the bending
motion, the greater is the physical stress on the low back. Frequent
bending, regardless of weight, is not recommended.

■ Twisting: This motion puts uneven forces on the back, thereby, presenting additional
physical stress. The greater the twist, the more physically stressful the task.

■ Reaching: The distance away from the body that a load is held
greatly affects the forces on the back, shoulders, and arms. The
farther the reach, the more physically stressful the task

■ One-Handed Lifts: The Tables cannot be used to evaluate one-
handed tasks. By nature, these tasks place uneven loads on the back
and present a greater physical stress than two-handed lifts

■ Handholds: Inability to get a good grip on the load
presents a greater physical stress.

■ Catching or Throwing Items: The Tables cannot be used to evaluate
these types of tasks. Any task involving catching or throwing items is
physically stressful and, therefore, a good candidate for redesign.

Population Percentages
The population percentages in these Tables are based on weights selected by subjects
in the laboratory working as hard as they could without straining themselves, or without
becoming unusually tired, weakened, overheated, or out of breath. Jobs designed
ergonomically should fit most workers. That is why 75 percent of the female work
population is used as a design starting point.

■ Do not use population percentages in the Tables to determine whether male or
female workers can perform certain jobs and then place workers accordingly.

■ Use the Tables to design manual handling jobs with physical requirements so
that as many workers as possible can perform them without risk of injury.

Training
As previously mentioned, effectively using the Tables requires training in ergonomics
and task evaluation methods. Users of the Tables should be trained in collecting hand
distance, lifting distance, and task frequency measurements. Liberty Mutual Group
workers compensation insured customers may contact their Risk Control Consultant or
the Risk Control Consulting Center for more information.

Resources
Ciriello, V. M. (2001). The effects of box
size, vertical distance, and height on
lowering tasks. International Journal
of Industrial Ergonomics, 28:61-67.

Ciriello, V. M. & Snook, S. H. (1983).
A study of size, distance, height, and
frequency effects on manual handling
tasks. Human Factors, 25:5, 1983.

Ciriello, V. M., Snook, S. H., &
Hughes, G. (1993). Further studies of
psychophysically determined maximum
acceptable weights and forces.
Human Factors, 35:11, 175-186.

Ciriello, V. M., Snook, S. H., Blick,
A. C., & Wilkinson, P. L. (1990).
The effects of task duration on
psychophysically-determined
maximum acceptable weights and
forces. Ergonomics, 33:2, 187-200.

Ciriello, V.M., McGorry, R.W.,
Martin, S., & Bezverkhny, I.B. (1999).
Maximum acceptable forces of
dynamic pushing: comparison of two
techniques. Ergonomics, 42:1, 32-39.

Snook, S.H. (1978). The design
of manual handling tasks.
Ergonomics, 21:12-963-985.

Snook, S. H., & Ciriello, V. M. (1991).
The design of manual handling
tasks: revised tables of maximum
acceptable weights and forces.
Ergonomics, 34:9 1197-1213.

Waters, T.R., Putz-Anderson, V.,
& Garg, A.. (1994). Applications
Manual for the Revised NIOSH Lifting
Equation. U.S. Department of Health
and Human Services, Centers for
Disease Control, Cincinnati, OH,
DHHS (NIOSH) Publication No. 94-110.

libertymutualgroup.com/riskcontrolservices @LibertyB2B

The illustrations, instructions, and principles contained in the material are general in scope and, to the best of our knowledge, current
at the time of publication. Our risk control services are advisory only. We assume no responsibility for: managing or controlling
customer safety activities, implementing any recommended corrective measures, or identifying all potential hazards.
No attempt has been made to interpret any referenced codes, standards, or regulations. Please refer to the appropriate government
authority for interpretation or clarification.
Insurance underwritten by Liberty Mutual Insurance Co. or its affiliates or subsidiaries.
© 2017 Liberty Mutual Insurance, 175 Berkeley Street, Boston, MA 02116. RC 5812 07/17

http://www.libertymutualgroup.com/riskcontrolservices

HAZARD ZONE JOBS CHECKLIST
For each “caution zone job” find any physical risk factors that apply. If a hazard exists, it must be reduced
below the hazard level or to the degree technologically and economically feasible.

Movements or postures that are a regular and forseeable
part of the job, occurring more than one day per week, and
more frequently than one week per year.

Hazard
Exists

Job Position evaluated:

Date:

No. of
employees in
these jobs?

Awkward Posture Comments/Observations

1. Working with the hand(s)
above the head, or the
elbows above the shoulders

More than
4 hours

total per

day



2. Repeatedly raising the
hand(s) above the head, or
the elbow(s) above the
shouder(s) more than once
per minute