Macroergonomic Methods
Appendix 6.4 Table of Exposure Scores
7.4 Example
Ergonomics takes high priority in the design and development of pallets for Jaguar Cars Ltd., U.K., and RULA has become one of the key criteria used by them and the suppliers.
7.4.1 RULA Used in Design and Development Process
Jaguar uses RULA in its standards documentation for pallet/box manufacture to enable the company and its suppliers to assess and improve the ergonomics of their pallets before production commences, thereby avoiding disruption and risk of injury during steady-state production. As part of the development process, all suppliers complete a full RULA risk assessment on the use of each pallet prototype, and they make any necessary changes to eliminate any risk to the operators. The engineers and physiotherapist at Jaguar have found that this process minimizes bending, stretching, or twisting.
When materials for the X200 series were supplied, RULA was used to assess the unpacking task. The initial unpacking task forced the operator to reach into the box, as seen in Figure 7.2. The musculoskeletal risk increased as the box was emptied. The RULA scoring of the posture depicted in Figure 7.2 is presented in Table 7.2 along with relevant comments on the scoring. It is useful to follow the score sheet and body part diagrams (Figure 7.1) while reading Table 7.2.
TF1539_book.fm Page 3 Wednesday, July 28, 2004 10:36 AM
7-4 Handbook of Human Factors and Ergonomics Methods
FIGURE 7.1ARULA software assessment form.
RAPID UPPER LIMB ASSESSMENT Client:Date/time:Assessor:
Right Side:
Right UpperArm
Shoulder is raised Upper arm is abducted Leaning or supporting the weight of the arm
Right Lower Arm Working across the midline of the body or out to the side
Right Wrist Wrist is bent away from midline
Right Wrist Twist
Force & Load for the Right Handside
SELECT ONLY ONE OF THESE: No resistance Less than 2 kg intermittent load or force 2–10 kg intermittent load or force 2–10 kg static load 2–10 kg repeated loads or forces 10 kg or more intermittent load or force 10 kg static load 10 kg repeated loads or forces Shock or forces with rapid buildup Muscle Use Posture is mainly static, e.g., held for longer than 1 min or repeated more than 4 times per minute TF1539_book.fm Page 4 Wednesday, July 28, 2004 10:36 AM
Rapid Upper Limb Assessment (RULA) 7-5
FIGURE 7.1BRULA software assessment form.
Left Side:
Left UpperArm
Shoulder is raised Upper arm is abducted Leaning or supporting the weight of the arm
Left Lower Arm Working across the midline of the body or out to the side
Left Wrist Wrist is bent away from midline
Left Wrist Twist
Force & Load for the Right Handside
SELECT ONLY ONE OF THESE: No resistance Less than 2 kg intermittent load or force 2–10 kg intermittent load or force 2–10 kg static load 2–10 kg repeated loads or forces 10 kg or more intermittent load or force 10 kg static load 10 kg repeated loads or forces Shock or forces with rapid buildup Muscle Use Posture is mainly static, e.g., held for longer than 1 min or repeated more than 4 times per minute TF1539_book.fm Page 5 Wednesday, July 28, 2004 10:36 AM
7-6 Handbook of Human Factors and Ergonomics Methods
FIGURE 7.1C RULA software assessment form.
TABLE 7.1 RULA Action Levels
Action level 1 Score of 1 or 2 indicates that the posture is acceptable if it is not maintained or repeated for long periods
Action level 2 Score of 3 or 4 indicates that further investigation is needed, and changes may be required
Action level 3 Score of 5 or 6 indicates that investigation and changes are required soon Action level 4 Score of 7 indicates that investigation and changes are required
immediately
© 2001
NeckNeck TwistNeck Side-bendTrunkTrunk TwistTrunk Side-bendLegs
Legs and feet are well supported and in an evenly balanced posture.
Legs and feet are NOT evenly balanced and supported.
Force & Load for the Neck, Trunk, and Legs
SELECT ONLY ONE OF THESE:
No resistance Less than 2 kg intermittent load or force 2–10 kg intermittent load or force
2–10 kg static load 2–10 kg repeated loads or forces 10 kg or more intermittent load or force 10 kg static load 10 kg repeated loads or forces Shock or forces with rapid buildup Muscle Use Posture is mainly static, e.g., held for longer than 1 min or repeated more than 4 times per minute TF1539_book.fm Page 6 Wednesday, July 28, 2004 10:36 AM
Rapid Upper Limb Assessment (RULA) 7-7
It is clear from the RULA assessment of Figure 7.2 that ergonomic risks were present that required modification. The body parts at risk were the back and neck postures, with overreaching causing risk to the upper arms. Figure 7.3 illustrates the solution, a hydraulic tilter controlled by the operator to allow the height and angle of the pallet to be adjusted. This device provided a RULA score of 1 to 4, depending on the position of the item in the box.
7.4.2 RULA Used in Early Intervention and Risk Assessment Related to Musculoskeletal Strains and Sprains
As part of production operations, Jaguar has introduced RULA assessments as one of its procedures when:
1. There has been a work-related strain/sprain reported 2. The risk assessment identifies that an assessment is required 3. There has been a change to a process
4. There is an operator concern
Figure 7.4 provides an outline of the processes in place to find practical solutions to any of the above criteria. If a change cannot be made in the short term, then containment measures are introduced, such as increasing recovery time or increasing job rotation. RULA assessments are made accessible to the personnel carrying out the task by keeping them in the immediate vicinity.
The process outlined in Figure 7.4 offers a participatory systematic approach to problem solving using skills and knowledge from relevant personnel in the company. In this process, RULA provides an objective measure around which changes can be suggested and investigated, with the ultimate goal of implementing the best-practice solution.