Civil Engineering Reference
In-Depth Information
The tool does not account for some workplace factors that may increase the likelihood of MSDs,
namely sustained non-neutral postures, contact stresses, low temperatures, and vibration exposure.
If these factors are present, then professional judgment should be used to determine if exposure is
above the TLV. Also, the TLV is not meant to apply to work conditions that include multiple tasks.
The TLV does, however, provide a useful tool to quickly assess mono-tasks. It can be quick, easy to
use, and easy to interpret. It also allows the user flexibility to be more accurate with an additional invest-
ment of time and expertise. Appropriate uses of the TLV include identifying potential jobs as candidates
for ergonomic interventions and for setting priorities for resource allocation. The TLV can also be used as
a metric to determine if interventions have had the desired effect by performing an assessment before and
after implementation and comparing the results.
34.4.3 Entire Body Assessment Tools
34.4.3.1 Rapid Upper Limb Assessment
McAtamney and Corlett (1993) developed a survey method to quickly screen a working population for
the risk of work-related upper extremity MSDs. The method, called Rapid Upper Limb Assessment
(RULA) was developed so that the screening could be performed without the need for specialized equip-
ment. Despite its name, RULA also accounts for posture, force, and repetition of the neck, trunk,
and legs.
Some MSD risk factors that can be assessed with the RULA are numbers of movements, static muscle
work, force, work postures determined by equipment and furniture, and time worked without a break. To
determine the final RULA score, the analyst categorizes the posture of different body parts into prede-
termined categories. (Up until the final score is calculated, the wrist and arm values and the neck,
trunk, and leg values are calculated separately.) Charts are then used to combine the postures to
obtain the general posture scores. These general posture scores are then combined with muscle use
scores and force
load scores. Finally, the wrist and arm score and the neck, trunk, and leg score are com-
bined with a table to determine the final score.
The authors reported an assessment of the validity of RULA based upon 16 computer operators, and
they found significant relationships between individual RULA body part scores and the development of
pain or discomfort for the neck and lower arm, but not for the trunk, upper arm or risk. A reliability test
was performed by having over 120 professionals who had been trained on the use of RULA score video-
taped examples of work tasks. The authors state that there was a “high consistency of scoring amongst
subjects,” but there are no statistics to support this claim. So, further validity and reliability studies of this
assessment tool are warranted.
The main benefits of RULA for the practitioner is its low cost, its ease and quickness of use, and the
simplicity of the results — the final score is represented as a single number. So, the tool is suited be used
by ergonomics teams to make recommendations to management. McAtamney and Corlett (1993) state
that in their experience, “Managers were quick to recognize and remember the grand scores and their
associated action levels.” They also indicated that the tools lend themselves well to reevaluating
changes in musculoskeletal loading after changes were made. They recommend the tool be used as a
screening method or incorporated into a wider group of assessment tools.
/
34.4.3.2 Job Safety Analysis
The Job Safety Analysis (JSA), an analysis tool that has been commonly used in industry for years to
identify and rectify safety hazards in the workplace, also can be used to identify MSD risk factors and
potential intervention strategies (Peterson, 2003). The JSA process involves breaking a task into individ-
ual steps. For each step, potential hazards (including MSD risk factors) are identified and then work prac-
tices, procedures, or engineering controls are listed to ameliorate the hazards.
The process used when completing the JSA is critical to its success. It is imperative that workers doing
the job are involved to ensure that the actual job steps are included and that recommendations are feas-
ible. Worker involvement also increases acceptance of recommendations. Furthermore, solutions should
Search WWH ::
Custom Search