The objective of this study was to evaluate three seats amongst a population of metropolitan bus drivers as they drove a standardized test route including city streets, old and new freeways, and a street segment containing ten large speed humps. Three comparisons were made: 1) comparing seats made by different manufactures (Seat 1 and Seat 2), 2) comparing seats with a standard foam (Seat 2) and silicone foam (Seat 3) seat pans, and 3) comparing WBV exposures based on road types. Whole body vibration (WBV) exposures were measured using a tri-axial seat pan accelerometer and the attenuation capabilities of each seat were evaluated by comparing the vibrations measured at the floor and seat-of the bus. There were significant WBV exposure differences between the various street types, which were shown across all seat types. The city street and older freeway segments had the highest WBV exposures with both segments producing WBV exposures slightly above the action limit for Vibration Dose Value (VDV(8)). Relative to Seat 2, Seat 1 performed better at attenuating impulsive and shock related WBV exposures, however, neither seat performed significantly better when Average Vibration (Aw(8)) and VDV(8) WBV exposures were compared. In addition, no performance differences were seen between the standard foam (Seat 2) and silicone foam (Seat 3) seat pans. This study provided a unique opportunity to explore WBV exposures among bus drivers and potential ergonomic interventions in the way of seat options to reduce WBV exposures and potentially reduce workplace injuries.
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