Reducing whole body vibration to improve the safety and health of bus drivers

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By by Peter W. Johnson, PhD, MS; Steven D. Hudock, PhD, CSP; Thomas McDowell, PhD; and Elizabeth Dalsey, MA.

On the road every day, transportation workers are responsible for the safe delivery of passengers, materials and goods across the United States. Bus drivers ensure our kids and family members arrive safely. Bus drivers are vital to our economy, but their job can put them at increased risk for health problems. In 2014, musculoskeletal disorders accounted for 23% (n=3,400) of all injuries and illnesses resulting in days away from work for bus drivers.¹

Bus drivers are vulnerable to health risks as their job requires long hours sitting while absorbing vehicle vibrations from the roads and highways. Whole body vibration occurs as a vehicle travels over roads and the vibrations are transferred through the floor of the vehicle or seat into the driver’s legs and spine. Vehicle design, type of driver seat including suspension and seat cushions can affect exposure to whole body vibration. The major impact of whole body vibration is the development of musculoskeletal disorders, most commonly lower back pain, although upper extremity disorders such aches and pains and weakness in the arm, shoulder, or the neck can occur as well.² Research has also shown that whole body vibration contributes to other negative health effects including cardiovascular, gastrointestinal, nervous and urological disorders.³ It is important to understand how to minimize exposure to whole body vibration to reduce negative health effects on bus drivers.

The Study

To address whole body vibration exposure, researchers set out to determine the contribution of bus type on whole body vibration.⁴ Two different buses, a high-floor bus mainly used for longer commuter routes and a low-floor bus often used as intercity buses with easy entry and exit for passengers, were driven to compare whether performance differences existed. Both buses were driven on a standardized route which included four road types to represent typical terrain for bus drivers: newer smooth freeway, rough older freeway, city streets and roads with speed bumps. Different drivers drove each bus with 12 professional bus drivers operating the high-floor bus and 15 professional bus drivers operating the low-floor bus. The buses used the same brand new, air-suspension seat, and no passengers were onboard. Whole body vibration exposures were evaluated using two international standards, ISO 2631-1 (1997) and ISO 2631-5 (2004) to assess human exposure and multiple shocks.