Abstract
An ergonomic analysis aiming at the identification of the main reasons for urban bus drivers' early retirement included the characterisation of the vibrations transmitted through their seat. The assessment was accomplished in terms of vibration magnitude, dominating frequencies and the most risky stimuli's direction. Due to the importance of vehicle-terrain interactions on the vibration transmission process, the road surface role was also investigated. This preliminary study involved a single brand of buses and is being extended to the entire bus fleet.
The first results revealed vertical solicitations to be the most intense, reaching acceleration values of 0.5 m s-2, and significant frequencies were located below 16 Hz, where the human's vulnerability to vibrations is high.
Apparently, horizontal vibrations may be neglected in comparison to the vertical ones and the seat pan is the principal vibration-transferring surface. The driving speed seems to have taken advantage over the road's roughness on the vibration level control.
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