Repeatability of a Checklist for Evaluating Cab Design Characteristics of Heavy Mobile Equipment

Abstract

Risk factors associated with the development of musculoskeletal discomfort and disorders during the operation of heavy mobile equipment include whole-body vibration and awkward and sustained joint postures of the shoulders, neck, and trunk. Cab design may influence awkward postures of the joints, and task duration may influence duration of exposure to awkward and static postures and whole-body vibration. To reduce exposure to risk factors related to the interface between cab design and task, it may be necessary for manufacturers to address cab design. This study assessed the repeatability of a cab design checklist developed to evaluate various design characteristics that can influence exposure to risk factors for musculoskeletal discomfort. The ability of the cab design checklist to identify posture-related deficiencies of design was also assessed. The checklist was used by two administrators across 10 pieces of heavy construction equipment. Video analysis was performed to quantify postures of the neck, shoulder, and trunk; correlation analysis was used to determine whether specific questions from the checklist were associated with the identification of awkward postures. The repeatability assessment resulted in kappa coefficients ranging from 0.52 to 1.0 (good-to-excellent reproducibility) across each piece of equipment, and an overall kappa coefficient of 0.77 (excellent reproducibility) when considering all equipment together. Results from the correlation analysis showed that shoulder flexion posture was correlated with scores from the cab design checklist. However, results of the cab design checklist were not significantly correlated with shoulder abduction or awkward postures of the neck and trunk. Results suggest that the cab design checklist may be useful for identifying cab design characteristics that need further improvement and for identifying design characteristics that increase shoulder flexion. The strength of the repeatability assessment suggests that outcomes of the cab design checklist administered by different individuals may be consistent, independent of the type of equipment being assessed.

Keywords:

• awkward postures
• construction
• operating engineers
• postural analysis
• whole-body vibration

ACKNOWLEDGMENTS

This study was funded by the National Institute for Occupational Safety and Health, Spokane Research Lab (NIOSH-SRL). The authors are grateful for the participation of the members of International Union of Operating Engineers (IUOE) Training Center at Ellensburg, Washington.

The authors would also like to thank researchers from NIOSH-SRL: Richard E. Miller, Grant W. King, and Muthukaruppan Viswanathan (contractor) for collecting field data for this study. The authors appreciate the support of IUOE Headquarters in performing this study.

The findings and conclusions in this article are those of the authors and do not necessarily represent the views of National Institute for Occupational Safety and Health (NIOSH). Mention of specific manufacturers does not imply endorsement by NIOSH.