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Posted by Sadia Waseem
One of the most important tasks an industrial engineer has is to make sure that the factory floor is safe for workers. In manufacturing safety not only refers to avoiding incidents that make the headline, but also making sure that the environment is optimized in such a way that workers experience less fatigue and discomfort, can focus better and work more efficiently.
There are various methods for evaluating workplace safety ranging from complex analyses to simple methods such as Rapid Upper Limb Assessment (RULA), which doesn’t require expensive equipment and can be done with a single worksheet.
In this article, we will discuss all you need to know about RULA and how you can conduct it in an easier way with the help of AI faster, more efficient and error-free results.
RULA Rapid Upper Limb Assessment was developed by Dr. Lynn Mc. Atamney and Professor E. Nigel Corlett, ergonomists from the University of Nottingham in England. RULA assessment was designed to assess the risk factors associated with upper limbs among workers. The assessment considers the biomechanical and postural load requirement of the job on the neck, trunk, and upper body limbs and gives a quick and systematic assessment of postural risks.
A single worksheet is used to evaluate body postures, loads, and frequency of work, based on which scores are assigned to different body parts based. Scores are directly proportional to MSD risk.
RULA was developed to:
While there are various other ergonomics assessment tools, RULA is used for specific reasons. Here are some benefits of using RULA:
RULA assessment uses a series of illustrations of different body postures, and a numerical score is allocated to the most observed posture. Body parts are divided into two groups: group A and group B. Group A consists of the upper arm, lower arm, and wrist, and Group B consists of the neck, trunk, and legs.
Scores are assigned to upper arms based on the following factors:
Body Position | Score |
0° -20° of flexion of arm | 1 |
20°-45° of flexion | 2 |
45°-90° of flexion | 3 |
<90° of extension | 4 |
Additional Consideration | |
Arms abducted | 1+ |
Shoulders elevated | 1+ |
No support to the arm | 1+ |
Support to the arm | 1- |
The scores for lower arms are assigned based on:
Body Position | Score |
60° -100° of flexion of upper arm | 1 |
>60° or <100° of flexion | 2 |
Additional Consideration | |
Twisting of forearm | 1+ |
The wrist scores range from 1-3 and based on following movement of wrist:
Body Position | Score |
0° of flexion of wrist | 1 |
15° of flexion | 2 |
>15° of flexion | 3 |
Additional Consideration | |
Wrist bend away from the middle | 1+ |
Twisting of wrist in mid-range | 1+ |
Twisting near the end of range | 2+ |
Neck is assessed in the following way:
Body Position | Score |
0° -10° of flexion of neck | 1 |
10°-20° of flexion | 2 |
<20° of flexion | 3 |
In extension | 4 |
Additional Consideration | |
Twisting of neck | 1+ |
Side-bending of neck | 1+ |
Scores are assigned based on different position of trunk:
Body Position | Score |
0° of flexion and if trunk is well-supported | 1 |
0° -20° of flexion | 2 |
20° -60° of flexion | 3 |
<60° of flexion | 4 |
Additional Consideration | |
Twisting of trunk | 1+ |
Side-bending of trunk | 1+ |
Scores are assigned based on the following postures of legs:
Body Position | Score |
Feet are well-supported, and weight is evenly distributed | 1 |
Legs are not stable and weight is not evenly distributed | 2 |
In RULA, force analysis involves assigning a score based on the exertion required to perform a job. The score considers the weight of the load and its impact on muscles. Scores are assigned on the following basis:
Force/Load | Score |
Load<4.4 Lbs. | 0 |
4.4-22 Lbs. of intermittent load | 1+ |
4.4-22 Lbs. of static or repeated load | 2+ |
Load>22 Lbs. | 3+ |
Muscle analysis in RULA involves evaluating the duration of a task and the frequency of muscular activities during that task. It helps in highlighting the potential risk of muscle fatigue and the probability of MSDS. Scores are assigned based on muscle use in the following way:
Muscular Movement | Score |
Posture static i.e. held for 10 minute | 1+ |
Action repeated 4 times per minute | 1+ |
The scores are then combined from different body parts, force/load analysis, and muscle use analysis to calculate the final score and assess the risk of musculoskeletal disorders. The following steps are required to calculate the final scores:
The final scores range from 1-7 and are interpreted as:
Even though it requires a simple worksheet, conducting RULA assessment manually can be prone to errors and it is subjective as well. The alternative is to use an AI-powered software that uses advanced AI algorithms and computer vision to conduct various ergonomics assessments such as REBA assessment, RULA assessment, Snook Table, NIOSH lifting equation, etc.
The working of the RULA assessment in Kaizen Copilot is quite simple. You only need a smartphone to record the video of your process and upload it to Kaizen Copilot. The software then assesses the posture of a worker and generates RULA scores based on it.
Here is how RULA Assessment works in Kaizen Copilot:
RULA Score: Final RULA scores are assigned based on the posture analysis. Low scores indicate minimal risk situation while as the score increase risk of the injury increases.
Posture Analysis: It illustrates the skeleton of the body graphically in addition to color-coded images that indicate each limb’s high, medium, and low risks. High risk is indicated by red, medium risk by yellow, and risk-free zones by green. For every posture, you can find high RULA score regions that increase the risk of MSDs in workers.
Time-Based Analysis: A time-based analysis evaluates the video as a whole. Green on the cycle assessment bar denotes a satisfactory job, while red usually denotes a high-risk area that requires quick attention. In addition, it indicates the portion of the body that is riskier and the overall proportion of the body that is not in a safe position.
Body Segment Analysis: The risk of occurrence for various body segments over the entire duration is displayed on the line chart in the body segment analysis. You can select the body part for which you would like more in-depth information.
The analytics display the likelihood of risk occurrence for the specific body type as well as the overall amount of time a worker will be exposed to these dangers. Recovery time shows the average amount of time between each risky activity, and average length represents the risk time for each activity. Activities below the line are safe, but those beyond the line are dangerous, as indicated by the red dotted lines.
Interpreting the Results
The Final RULA scores range from 1 to 7. Understanding these scores is crucial to implementing appropriate modifications in the process. Here’s a breakdown of the scores and the suggestions based on the scores:
Interpretation: The posture is generally acceptable and not risky if not repeated for long periods.
Action: Generally, no action is required for these postures. Conduct periodic workstation checks to ensure ergonomic principles are maintained.
Example: Implement a monthly ergonomic review process.
Interpretation: Investigate the posture and implement changes where necessary.
Action: Implement control measures to reduce risk. This may include introducing more frequent breaks, improving work postures, or making minor workstation adjustments.
Example: Provide ergonomic training to employees and introduce breaks every hour or change the worker’s duty.
Interpretation: Actions and changes are required soon.
Action: Implement control measures such as redesigning a workstation, modifying job tasks, or introducing job rotation to reduce repetitive strain.
Example: Re-design the workstation to improve arm positioning and invest in equipment which is ergonomically safe.
Interpretation: Immediate actions and changes are required.
Action: Take urgent action to address high-risk factors. You may have to make significant changes to the work environment, tools, or job design.
Example: Immediately modify the current work process and conduct RULA assessment again to analyze the effect of these changes.
Despite its limitations, RULA Assessment is still an effective tool for identifying and eliminating ergonomic hazards. Through systematic evaluation of upper limb postures, force requirements, and repeated motions, RULA offers vital insights into potential muscular disorders.
Today, AI is making ergonomics easier. With Kaizen Copilot, you can eliminate manual calculations and streamline the evaluation process by rapidly analyzing workplace operations and producing precise RULA scores. In addition to saving time, Kaizen Copilot’s automation and accuracy allow for more regular and consistent evaluations, which empowers manufacturers to proactively address ergonomic concerns.
Ready to transform your workplace ergonomics? Book a free demo today!
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