The Characterization of Whole-Body Vibration Exposures in Forklift Operators

Abstract

Prolonged and/or frequent exposures to whole-body vibration (WBV) are known factors for musculoskeletal disorders. Although forklift operators are heavily exposed to WBV, there is still a lack of studies that systematically evaluate different interventions for mitigating WBV exposures. The present dissertation objectives were: 1) to characterize forklift operators' exposure to WBV, and 2) to evaluate the effects of three different potential interventions (i.e., forklift vibration damping systems, tire selection, and driver seat suspensions) in reducing the forklift operators' exposures to WBV. To achieve these objectives, three field-based studies were conducted with professional forklift operators to measure and analyze WBV exposures per International Organization for Standardization (ISO) 2631-1 WBV standards, and self-reported musculoskeletal pain during half of the regular shifts (approximately 4 hours). The results of the first study showed that the operators of the forklift with the mast-based vibration damping system experienced lower WBV exposures and lower self-reported musculoskeletal pain compared to the other forklift operators without the mast-based vibration damping system. A second study found that the operators of the forklifts equipped with solid-tires experienced lower WBV exposures and lower self-reported pain than the operators of the forklifts equipped with pneumatic-tires. These results followed a dose-response relationship in those lower WBV exposures corresponded to lower self-reported musculoskeletal pain levels. Lastly, a third study revealed that the seat suspension of the forklift driver seat attenuated the majority (approximately 46 %) of the forklift's floor-measured vibration; however, the amount of vibration attenuated by either the seat suspension and/or the seat cushion vibration was weight dependent.