Exposure of bus drivers to vibration

Status:

completed 08/2005

Aims:

The Directive 2002/44/EC governing vibration requires a risk assessment to be conducted of individual workplaces. For this purpose, measurements of vibration exposure were performed under representative conditions in order to assess the hazard posed to bus drivers by whole-body vibration. The results of the measurements were used for prevention purposes. They can also be used for hazard assessment during investigations into vertebral spinal injury, a formally recognized occupational disease. A better driver's seat may yield an improvement in working conditions. Knowledge of the vibration excitation spectrum is required for this purpose.

Activities/Methods:

The exposure experienced by drivers was measured on 64 buses, comprising 48 service buses, 13 tour coaches, and three service coaches. The studies were conducted on representative routes, where applicable with stops. The frequency-weighted acceleration at the vibration transmission points at the chassis/seat mounting point and driver's seat/driver interfaces were measured in the three axes of vibration, viz. x (back-chest), y (shoulder-shoulder) and z (spine). The frequency-related vibration excitation (spectrum) at the seat mounting point was also measured.

Results:

For the buses studied, the frequency-weighted acceleration values on the seat for the vertical (z) axis of vibration (axis of the driver's spine) lie between 0.20 and 0.72 m/s². On all buses, the z axis is the axis with the highest vibration impact. No driving time limit need generally be imposed for the usual shift duration in order to prevent the incidence of long-term health hazards in the form of vertebral spinal injury. If, for reasons of prevention, the weighted acceleration value over an eight-hour period is not to exceed 0.63 m/s², then of the buses studied, two service buses manufactured in 1974 and 1992 and one double-decker bus manufactured in 1956 should be driven less than eight hours each day without improved seats. On two coaches manufactured in 1983 and 1987, the daily duration of vibration exposure should not reach ten hours. Very good seats are available which can be used in place of less suitable models on a case-by-case basis.

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