Acknowledgments
8.3 Procedure
REBA has six steps:
1. Observe the task.
2. Select the postures for assessment.
3. Score the postures.
4. Process the scores.
5. Establish the REBA score.
6. Confirm the action level with respect to the urgency for control measures.
8.3.1 Observe the Task
Observe the task to formulate a general ergonomic workplace assessment, including the impact of the work layout and environment, use of equipment, and behavior of the worker with respect to risk taking.
If possible, record data using photographs or a video camera. However, as with any observational tool, multiple views are recommended to control for parallax errors.
8.3.2 Select Postures for Assessment
Decide which postures to analyze from the observations in step one. The following criteria can be used:
• Most frequently repeated posture
• Longest maintained posture
• Posture requiring the most muscular activity or the greatest forces
• Posture known to cause discomfort
• Extreme, unstable, or awkward posture, especially where a force is exerted
• Posture most likely to be improved by interventions, control measures, or other changes The decision can be based on one or more of the above criteria. The criteria for deciding which postures to analyze should be reported with the results/recommendations.
8.3.3 Score the Postures
Use the scoring sheet (Figure 8.1) and body-part scores (Table 8.4 and Table 8.5) to score the posture.
The initial scoring is by group:
• Group A: trunk, neck, legs (Figure 8.2)
• Group B: upper arms, lower arms, wrists (Figure 8.3)
Group B postures are scored separately for the left and right sides, as indicated on the scoring sheet (Figure 8.1). Note that additional points can be added or subtracted, depending on the position. For example, in Group B, the upper arm can be supported in its position, and so 1 point is deducted from
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its score. The load/force score (Table 8.1), the coupling score (Table 8.2), and the activity score (Table 8.3) are allocated at this stage. This process can be repeated for each side of the body and for other postures.
8.3.4 Process the Scores
Use Table A (Table 8.4) to generate a single score from the trunk, neck, and legs scores. This is recorded in the box on the scoring sheet (Figure 8.1) and added to the load/force score (Table 8.1) to provide score A. Similarly the upper arms, lower arms, and wrist scores are used to generate the single score using Table B (Table 8.5). This is repeated if the musculoskeletal risk (and therefore the scores for the left and right arms) is different. The score is then added to the coupling score (Table 8.2) to produce score B.
Scores A and B are entered into Table C (Table 8.6), and a single score is read off. This is score C.
8.3.5 Calculate REBA Score
The type of muscle activity being performed is then represented by an activity score (Table 8.3), which is added to give the final REBA score.
8.3.6 Confirm the Action Level
The REBA score is then checked against the action levels (Table 8.7). These are bands of scores corre- sponding to increasing urgency for the need to make changes.
FIGURE 8.1 REBA scoring sheet.
L R
L R
L R Use Table A Use Table B
REBA Score Activity
Score +
+ +
Load/Force Coupling
Group A Group B
Use Table C
Score C
Score B Score A
REBA - Scoring Sheet
U A L A W T
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8-4 Handbook of Human Factors and Ergonomics Methods
FIGURE 8.2 Group A scoring.
Trunk
Movement Score
Upright 1
0°-20° flexion 0°-20° extension
2
20°-60° flexion
> 20° extension
3
> 60° flexion 4
Change score:
+1 if twisting or side flexed
Neck
Movement Score
0°-20° flexion 1
> 20° flexion or extension
2
Change score:
+1 if twisting or side flexed
Legs
Position Score Bilateral weight bearing,
walking or sitting
1 Unilateral weight-bearing, feather weight-bearing, or an
unstable posture
2
Change score:
+1 if knee(s) between 30° and 60° flexion +2 if knee(s) >60° flexion
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Rapid Entire Body Assessment 8-5
FIGURE 8.3 Group B scoring.
TABLE 8.1 Load/Force Score
0 1 2 +1
<5 kg 5–10 kg >10 kg Shock or rapid buildup of force Upper arms
Position Score 20° extenion to
20° flexion
1
> 20° extension 20° - 45° flexion
2
45°-90° flexion 3
> 90° flexion 4
Change score:
+1 if arm is:
• abducted
• rotated +1 if shoulder is raised -1 of leaning, supporting weight of arm or
if posture is gravity assisted
Movement Score
60°-100° flexion 1
<60° flexion
> 100° flexion
2
Movement Score
0°-15° flexion/extension 1
>15° flexion/extension 2
Change score:
+1 if wrist is deviated or twisted
Lower arms
Wrists
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TABLE 8.2 Load Coupling Score
0 (Good) 1 (Fair) 2 (Poor) 3 (Unacceptable)
Well-fitting handle and a midrange power grip
Handhold acceptable but not ideal
or
Coupling is acceptable via another part of the body
Handhold not acceptable, although possible
Awkward, unsafe grip; no handles
or
Coupling is unacceptable using other parts of the body
TABLE 8.3 Activity Score
Score Description
+1 If one or more body parts are static, e.g., held for longer than 1 min +1 If repeated small-range actions occur, e.g., repeated more than 4 times per
minute (not including walking)
+1 If the action causes rapid large-range changes in postures or an unstable base
TABLE 8.4 Table A: Scoring for Body Parts A (Trunk, Neck, Legs) Neck
1 2 3
Legs 1 2 3 4 1 2 3 4 1 2 3 4
Trunk
1 1 2 3 4 1 2 3 4 3 3 5 6
2 2 3 4 5 3 4 5 6 4 5 6 7
3 2 4 5 6 4 5 6 7 5 6 7 8
4 3 5 6 7 5 6 7 8 6 7 8 9
5 4 6 7 8 6 7 8 9 7 8 9 9
TABLE 8.5 Table B: Scoring for Body Parts B (Upper Arms, Lower Arms, Wrists) Lower Arm
1 2
Wrist 1 2 3 1 2 3
Upper Arm
1 1 2 2 1 2 3
2 1 2 3 2 3 4
3 3 4 5 4 5 5
4 4 5 5 5 6 7
5 6 7 8 7 8 8
6 7 8 8 8 9 9
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8.3.7 Subsequent Reassessment
If or when the task changes due to interventions or control measures, the process can be repeated, and the new REBA score can be compared with the previous one to monitor the effectiveness of the changes.