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Exploring the Association between Truck Seat Ride and Driver Fatigue

Author(s): Wang, Davies, Johnson, Du, Viventi

Slidedeck Presentation Only (no paper submitted):

3B - Wang

Abstract:

It is believed that exposure to whole-body vibration (WBV) is associated with several adverse health outcomes and may increase truck driver fatigue, and driver fatigue may contribute to vehicular accidents. Previous studies have focused on musculoskeletal disorders associated with truck-induced WBV exposures, whereas the effects of WBV on truck drivers cognitive fatigue have been less rigorously studied. The aim of this study, using a group of truck drivers performing their actual work, was to determine whether truck-induced WBV had any effects on truck driver fatigue. Two seats, with very different ride characteristics (smooth vs rough) were compared to determine if there were any difference in the fatigue the truck drivers experienced after using the smooth- and rough-riding seats. A truck seat that reduces driver fatigue may decrease the chances of fatigue-related accidents. Twenty-five regional, line-haul truck drivers were recruited (mean age 43.2). Drivers used two different truck seats on two separate days, and the two seats had very different ride characteristics (smoother vs rougher ride). During each shift, the drivers drove on the same 280 km route for 11 hours. The two seats included the trucks' original-fitted seat, air-suspension seat and an aftermarket active suspension seat (a truck seat with electronics and a suspension which cancels vibration very similar to the way noise-cancelling headphones reduce unwanted noise). The active suspension seat has been shown to reduce the truck drivers' average vibration exposures by up to 55%. Seat and floor WBV exposures were measured according to international standards. With each seat, drivers were asked to perform a 5-minute Psychomotor Vigilance Task (PVT) on a tablet to assess their reaction times immediately before and after their shift. Three reaction time outcomes were compared between the two seats including: mean reaction times, the fastest reaction times, and lapses in reactions (the percentage of reaction times longer than 0.5 seconds). There were large differences in the seat-measured WBV exposures between the two seats with the active-suspension seat providing a much smoother ride compared to the original-fitted seat (50% reduction in seat-measured vibration, 0.27 m/s2 vs 0.54 m/s2). The fastest (p = 0.002) and mean (p=0.062) reaction times were slower and the risk of lapses increased (p = 0.015) after operating the truck with the original-fitted seat. The results showed that compared to the original-fitted, air suspension seat; the active suspension seat substantially improved the ride quality for the truck driver and reduced the seat measured WBV exposures by 50%. This improvement in ride quality also appears to affect driver cognitive fatigue by reducing the rate of fatigue experienced over the course of a shift. These study results indicate that: 1) exposure to WBV does appear to influence and affect truck driver fatigue, 2) smoother riding truck seats may reduce truck driver fatigue and 3) these smoother riding seats may ultimately contribute to a reduction in fatigue-related accidents, injuries and their associated costs.