Vehicle Design Influences Whole Body Vibration Exposures: Effect of the Location of the Front Axle Relative to the Cab

Abstract

Using a repeated measure design, this study compared differences in whole body vibration (WBV) exposures among 13 drivers who drove a truck with the cab over the front axle (cab-over design) and a truck with the cab situated behind the front axle (non-cab-over design). The drivers drove both trucks over a standardized route that comprised three distinct segments: a freeway segment, a city street segment with stop-and-go driving (traffic lights), and a city street segment without traffic lights. A portable WBV data acquisition system collected tri-axial time-weighted and raw WBV data per ISO 2631-1 and 2631-5 standards. Simultaneous global positioning system (GPS) data were also collected to compare vehicle speeds. The GPS data indicated that there were no speed differences between the two vehicles. However, average and impulsive z-axis vibration levels were significantly higher for the cab-over design than for the non-cab-over design. In addition, significant WBV exposure differences between road types were found, with the freeway segments having the lowest exposures and the city street segments without traffic lights having the highest exposures. Vehicle type and the associated WBV exposures should be considered when purchasing vehicles to be used by full-time professional vehicle operators.

Keywords:

• driving injuries
• ergonomics
• low back pain
• transportation industry

ACKNOWLEDGMENTS

This research was supported by the Washington State Medical Aid and Accident Fund, administered by the Department of Environmental and Occupational Health Sciences at the University of Washington. The authors would like to thank the drivers and staff (Gabrielle Toutonghi, Michael Harrell, and Dave Jager) of King County Metro Transit, Seattle, Washington, for participating in this research study and for their proactive approach to workplace safety and the advancement of the field of transportation-related ergonomics. King County Metro allowed access to out-of-service trucks for testing purposes and compensated their drivers for their participation time.