Affiliations: School of Kinesiology, University of Western Ontario,
London, Ontario, Canada | Rehab Science Program, University of Western Ontario,
London, Ontario, Canada
Note: [] Address for correspondence: Alan Salmoni, School of Kinesiology,
University of Western Ontario, London, Ontario, Canada N6A 3K7. E-mail: asalmoni@uwo.ca
Abstract: Background: It is often difficult to access a large sample of
vehicles in various work environments to evaluate worker exposure to vibration
such as in construction and mining. Thus the main purpose of the present
research was to test vibration exposure in a relatively large number of earth
scrapers. The second aim was to assess vibration exposure values on seat
transmissibility. Study Design: 33earth scrapers were assessed for both
exposure to whole-body vibration and seat transmissibility. Method: Two
triaxial accelerometers, one placed on the seat and one on the floor directly
below the seat, were used to gather whole-body vibration values (a_{w}). Each
machine was tested for a minimum of three complete work cycles: idling,
scraping, travelling full, dumping, travelling empty back to the scrape site. Results: Results showed that idling and scraping produced low levels of
vibration when compared to travelling and dumping. Second, when the a_{w}
values were compared to the EU safety standards [12] for an eight hour
work day, the data (z axis) exceeded the exposure action value (0.5 m/s^{2}<FORMULA>)
in all machines, and the exposure limit value (1.15 m/s<FORMULA>^{2}) in some.
Implications; Operators of the scrapers were being exposed to unsafe levels of
whole-body vibration. When the seats were assessed to see whether they were
attenuating operator exposure to vibration, many of the seat effective
amplitude transmissibility (SEAT) values exceeded 1.0. This meant that some of
the seats were actually amplifying the vibration present at the floor,
particularly in the y axis. Conclusion: Travelways should be kept smooth,
operating speeds reduced, and new seats, effective in all three axes, designed.
