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The RULA grid is a method of evaluating work postures. It highlights the risk of postures related to the observed work cycle and to issue a “rating” on this risk.

Introduction

The RULA grid, Rapid Upper Limb Assessment, was created in 1993 by McAtamney and Corlett1 of the University of Nottingham, England. It allows to assess the risk level of MSD regarding the postures, repetitive movements, forces required…

The principle of the method is based on the observation of the person’s work cycle and then on the evaluation of the postures adopted during these cycles. At the end of the evaluation, the RULA grid indicates the level of risk of the work sequence and it is inferred whether or not improvement actions are necessary and the level of urgency of implementation of these actions.

The method

The method is based on an evaluation in various stages described below. To follow it and make it in good conditions, you can help yourself with photos or videos of the different postures observed. Also, the method adapts well to the fact that one can evaluate at the same time the left side and the right side.

The method divides the body into two segments. Group A represents the upper part of the body (shoulder, elbow, handle). Group B is part of the lower body (leg, neck, trunk). Each part is recorded individually and is translated via a table into one note per group. Finally, a global score is assigned according to the notes of groups A and B and the necessary effort.

The process is as follows:

  1. Determine the work cycle to be observed.
  2. Select the posture to be evaluated.
  3. Decide which side of the body is going to be rated or so difficult, evaluate both sides at the same time.
  4. Determine the score for each side of the body.
  5. Get the overall score and the level of risk associated with it.
  6. Review the scoring of each part of the body to determine where the actions are needed.
  7. Redesign the workstation and introduce improvements towards the measured ergonomic risks.
  8. Once the changes are made, re-evaluate with the RULA grid to validate the results.

Group A Evaluation

This is to evaluate the upper body posture on which we will affix an adjustment variable. We will identify a note for:

  • The shoulders: The score depends on the position of the arms as well as an adjustment variable (seated position…).
  • Elbows: The score simply depends on the angle that the forearm makes with the upper arm.
  • wrists: The score depends on the position of the wrist in terms of bending but also of rotation.

Once the scores have been identified for these 3 parts of the body, we identify the overall score of the posture of Group A in the corresponding table.

Then, we adjust this score by adding the following factors:

  • Muscular activity: posture maintained static or not, repeated action…
  • Frequency and Effort: We take into account the level of effort and load according to a specific grid.

Global Score Group A

Finally, by summing all the previous factors, we get the overall score of group A.

Group B Evaluation

This is to evaluate the posture of the lower body on which, we will affix an adjustment variable. We will identify a note for:

  • the neck: The score depends on the position of the neck (flexion or extension) as well as an adjustment variable (rotation…).
  • the trunk: same as for the neck, the score depends on the position of the trunk in relation to the adjusted legs of the trunk rotation.
  • Legs: The score depends on the level of stability of the support or if one works in an unbalanced way, adjusted from the knee bends angle.

Once the scores are identified for these 3 parts of the body, the overall score of the posture of group B is identified in the corresponding table.

Then, we adjust this score by adding the following factors:

  • Muscular activity: posture maintained static or not, repeated action…
  • Frequency and Effort: We take into account the level of effort and load according to a specific grid.

Group B Global Score

Finally, by summing all the factors, we obtain the overall score of group B.

Final Score

Obtaining the final score is done in 2 times by looking for the value corresponding to the crossover of our posture score of group A and B.

Interpretation of the score

 

Method limit

This very powerful method does not allow to accurately evaluate tasks related to small manipulations of objects with hands.

It does not allow to evaluate tasks requiring long travel2 or very varied and unpredictable tasks.

It also lacks precision to analyze the frequency of efforts.

The method can be used to evaluate most of the tasks for which the worker mainly uses the upper limbs in a situation where he is seated or standing without making a lot of moves while he is working: working at The computer, in the manufacture, the sale3

Source

1 – L. Y. Mc Atamney, E. N. Corlett (1993) – RULA: A Survey method for the investigation of work-related upper limb disorders

2 – OHSCO (2008) – MSD Prevention Toolbox

3 – T. James (2010) – Ergonomic Evaluation tools

G. Laporte, S. Sellers (2010) – Common Tools for assessing ergonomics risk factors

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