The assessment of whole body vibration: A case study for bus drivers in the urban context of Rome

It is generally recognized that bus drivers are potentially being exposed to daily vibration levels higher than recommended by the international guidelines, especially on certain road types in the urban context. The literature shows up that the whole body vibrations exposure may contribute to low back pain and produce negative effects on the human health. The principal issue about the relationship between exposure and biodynamic response has not been clarified yet. The purpose of this paper is to determine the levels of vibration for bus drivers using A(8) and VDV(8) methods defined by ISO 2631-1 (1997) standard and highlight such as road condition influence on the WBV exposure. The measurements have been realized on different buses for fourteen drivers during their service route driving along urban routes in Rome with different driver's seat type. In addition, a test was realized on a new test route in order to highlight as the road type had a significant effect on all the whole body vibration exposure parameters. The vibration measurements were realized at the driver’s seat according to the recommendations of ISO 2631-1 (97). This guideline suggests measuring the vibration signal along the three translational axes on the seat pan but only the axis with the most severe vibration has been used in order to assess the driver's daily exposure. The data obtained show that the z-axis is the more stressed direction in all measurements with each surface road type. Furthermore, the results show that the type of seat employed reduces the vibration levels in a frequency range starting from 4 Hz up to 32.5 Hz. Finally this study points out as the severity of the whole-body vibration exposures in many work environments can be lessened by improvements of seating driving dynamics and road surface conditions.