Effects of High Levels of Obesity on Driver Seat Belt Fit

Obesity has been shown to increase the risks to motor vehicle occupants of some types of injury in crashes. The effects of obesity on injuries are not well understood and current prevention efforts do not effectively address the vulnerability associated with the high body mass index (BMI) cohort. Previous studies demonstrated that obesity effectively introduces slack in the seat belt restraint system by routing the belt further away from the underlying skeletal structures. These studies, however, have not measured individuals with a BMI ≥ 40 kg/m². Because approximately 5% of US adults have BMI exceeding this threshold, this study extends the previous research on the relationships between body habitus and belt fit with data from 52 male and female licensed drivers with BMI from 31 to 59 kg/m² (median 38 kg/m²). Consistent with previous research, higher BMI was associated with a lap belt position further forward and higher relative to the pelvis. On average, a person with a BMI of 40 places the belt 118 mm above and 68 mm forward of the anterior-superior iliac spine landmarks on the pelvis. Previous studies have shown mean values of 31 mm and 33 mm, respectively, for individuals with BMI 25. The data suggest a continued focus on improving restraint systems for individuals with high BMI is needed.

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  • Supplemental Notes:
    • This document was sponsored by the U.S. Department of Transportation, University Transportation Centers Program.
  • Corporate Authors:

    University of Michigan Transportation Research Institute

    2901 Baxter Road
    Ann Arbor, MI  United States  48109-2150

    Center for Advancing Transportation Leadership and Safety (ATLAS Center)

    University of Michigan
    2901 Baxter Road
    Ann Arbor, MI  United States  48109

    Office of the Assistant Secretary for Research and Technology

    University Transportation Centers Program
    Department of Transportation
    Washington, DC  United States  20590
  • Authors:
    • Jones, Monica L H
    • Ebert, Sheila M
    • Reed, Matthew P
  • Publication Date: 2016-8-18


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 85p

Subject/Index Terms

Filing Info

  • Accession Number: 01616912
  • Record Type: Publication
  • Report/Paper Numbers: ATLAS-2016-15
  • Contract Numbers: DTRT13-G-UTC54
  • Created Date: Nov 21 2016 1:26PM