Assessment of vibration levels associated with hand-held roadbreakers

The hand-held roadbreaker plays a vital role in enabling the British gas distribution workforce to install gas supply pipework. Hence, any potential problem which could lead to a restriction of the use of this equipment would present pipework installation departments with serious operational problems. A test program was therefore set up to enable risks to operators to be quantified. The vibration levels measured exceeded proposed limits laid down in current guidelines for vibration exposure. If these limits were realistic, a high prevalence of vibration-induced white finger (VWF) would have been expected. However, a survey of the workforce using the roadbreakers indicated a VWF prevalence of 20 times less than that predicted by the guidelines. It was concluded that a possible explanation could be that the current frequency-weighting factors used in the guidelines are inappropriate for application to this type of equipment with dominant frequencies below 25 Hz. The application of the current weighting factors to the test data produced during the program led to high weighted acceleration values and unrealistic dose-response relationships. It is proposed that the application of the various guidelines to the use of this equipment be reconsidered.