Whole body vibration exposures and seat effective amplitude transmissibilities of air suspension seat in different bus designs

Details

• Personal Author:
  Blood RP ; Johnson PW ; Lewis C ; Rynell PW ; Thamsuwan O
• Description:
  Introduction: Low back pain (LBP) is a prevalent work-related musculoskeletal disorder among professional drivers worldwide. LBP among drivers results in increased medical costs, decreased worker productivity, and missed work days. Whole body vibration (WBV) exposure is one of the risk factors contributing to the onset and development of LBP. Air suspension bus driver seats, which are now common in most city buses, perform well on rougher road types; however, these seats may not perform as well on smooth roads. The purpose of this study was to determine whether differences existed in WBV exposures when an air suspension seat was used in three common types of urban commuter buses: a high-floor coach bus, a low-floor bus, and a low-floor articulating bus. Methods: Using a standardized test route which included four road types: a smooth freeway, a rough freeway, a city street segment, and a road segment containing speed humps; eleven experienced bus drivers (average weight of 92.6 (SD 34.1) kg) drove a high-floor coach bus across the standardized test route and a different group of thirteen bus drivers (average weight of 95.3 (SD 13.8) kg) drove a low-floor bus and a low-floor articulating bus across the same route. The weights of the two groups of drivers were not significantly different (p-value = 0.80). All buses were equipped with the same air suspension seat (Model Q91; USSC Group; Exton, Pennsylvania, USA) and WBV exposures were collected using tri-axial accelerometers (Model 356B40; PCB Piezotronics; Depew, New York, USA) mounted at the seat and at the floor of the buses. Simultaneously, a Global Positioning System (GPS) collected the speed and position of the buses. The root mean square (r.m.s.) average WBV exposures were extrapolated to 8-hour daily values (A(8)) and evaluated per the European Union (EU) action limit for acceptable exposure levels (0.5 m/s2)5. Seat effective amplitude transmissibility (SEAT), which is the percentage of WBV exposures at seat compared to WBV exposures at floor of a vehicle, were calculated over the whole route and compared across the three buses. The A(8) exposures and SEAT values were analyzed using ANOVA methods to determine whether there were WBV exposure differences across the three buses. Differences were considered to be significant when p-values were less than 0.05. Results: As can be seen in Table 1, A(8) WBV exposures were significantly different across the buses. When the A(8) WBV exposures were compared by axis, the high-floor coach bus had the highest fore-aft (x) exposures, the low-floor articulating bus the highest side-to-side (y) exposures and the non-articulating low-floor bus the highest up-and-down (z) exposures. The A(8) WBV exposures in all buses did not exceed the EU's action limit. Based on the calculated SEAT values, the air suspension seat's performance was dependent on the bus type. Over the whole test route, the air suspension seat reduced the floor transmitted vibration by 8% on the high-floor coach bus, by 12% on the low-floor bus, and by 24% on the low-floor articulating bus. Discussion: Bus type influenced WBV exposures; therefore, a potential administrative control could be to rotate drivers across different buses so that they will not be exposed to a certain axis of WBV exposures for a long period of time. Since the air suspension seat did not perform that well on the high-floor coach and the non-articulating low-floor bus, a conventional static seat may be more effective on these buses and will be evaluated in future studies. [Description provided by NIOSH]
• Subjects:
  Automobiles Men Musculoskeletal Diseases Musculoskeletal System Occupational Health Risk Assessment Risk Factors Safety Vibration Women
• Keywords:
  Bus-drivers Drivers Equipment-design Exposure-levels Humans Motor-vehicles Musculoskeletal-system Musculoskeletal-system-disorders Risk-factors Vibration-effects Vibration-exposure Worker-health Workers

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• Publisher:
  University of Connecticut Health Center
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Abstract or Summary
• Place as Subject:
  OSHA Region 10 ; Washington
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  100-101
• NIOSHTIC Number:
  nn:20047082
• Citation:
  Proceedings of the 4th American Conference on Human Vibration: Fostering Collaborative Academic, Clinical, and Industrial Research in Vibration Exposure and Control, June 13-15, 2012, Hartford, Connecticut. Peterson DR, Asaki T, eds. Farmington, CT: University of Connecticut Health Center, 2012 Jun; :100-101
• Editor(s):
  Peterson DR; Asaki T
• Federal Fiscal Year:
  2012
• NORA Priority Area:
  Transportation, Warehousing and Utilities
• Performing Organization:
  University of Washington
• Peer Reviewed:
  False
• Start Date:
  20080901
• Source Full Name:
  Proceedings of the 4th American Conference on Human Vibration: Fostering Collaborative Academic, Clinical, and Industrial Research in Vibration Exposure and Control, June 13-15, 2012, Hartford, Connecticut
• End Date:
  20130831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:6f73e15500ef761b4e623a70ccf8ffe116a5595a8ad8babc8a9e92cf8a5c875df6cedd8c78aa6f7016ce113409a7e5ef1e60458d6ec4521b6d75734033968ff4
• Download URL:
  https://stacks.cdc.gov/view/cdc/202287/cdc_202287_DS1.pdf
• File Type:
  [PDF - 997.74 KB ]