Impact of Worn Shoes on Slipping

Details

• Personal Author:
  Beschorner K ; Haight J ; Moyer B ; Redfern M
• Description:
  Slip and fall accidents are a major source of occupational injuries. Heavy wear of shoes is associated with reduced coefficient of friction (COF) increased slipping risk. Worn tread loses the capacity to drain fluid from beneath the shoe, which causes the fluid to become pressurized and the friction to decrease. We have generated new knowledge on the impact of shoe wear on tread friction performance and slipping risk. Experiments were conducted to determine the contribution of footwear design to the shoe's friction response to wear (Aim 1), thresholds for when worn shoes should be replaced (Aim 2), physics-based models that explain wear progression and its impact on friction (Aim 3), validated the wear progression findings of Aims 1 and 3 using a prospective study on natural shoe wear (Aim 4), and validate the thresholds of Aim 2 using human slip data (Aim 5). Aim 1: Using controlled wear experiments in the lab, we characterized the friction response of shoes to progressive wear. Shoes experienced an initial increase followed by a steady decrease in friction performance. The decrease in friction aligned with an increase in fluid pressures, which indicate that a lack of fluid drainage explains this change in performance. Tread design influenced the shoe's response to wear and drainage capacity. In particular, shoes with increased tread coverage in the heel and with smaller tread lugs were associated with improved performance. Aim 2: The size of the worn region emerged as a critical factor for predicting the loss in friction performance for slip-resistant shoes. The study identified a size threshold (the base of a AAA or AA battery) that was associated with a reduced friction performance. This provides a basis for inspecting and monitoring shoes. Aim 3: Physics-based models were used to predict tread geometric changes of the tread in response to wear and the effect of wear on under-shoe fluid drainage. Both of these models demonstrated strong agreement with experimental results. Aim 4: Shoes were prospectively tracked in the workplace to monitor their change in friction performance due to natural wear. The wear progression trends observed in Aim 1 and modeled in Aim 3 were similarly observed for naturally worn shoes in workplaces. The model of under-shoe fluid drainage (Aim 3) predicted the friction progression of naturally worn shoes. Aim 5: Participants were exposed to a slippery contaminant, while wearing shoes of varying level of worn condition. The mechanistic model developed in Aims 2 and 3 was validated using this data. The developed battery test for inspecting shoes (Aim 2) was found to predict slipping risk. This study led to numerous outputs and outcomes. The work was disseminated by 12 published peer-reviewed papers and over 30 presentations that targeted the scientific, footwear industry, and safety professional communities. A direct translational product (intermediate outcome) resulting from the study was a quick and useful method to evaluate tread wear, termed the battery test. This test formed the basis for a NORA poster to communicate the test to restaurant and hospital employees. [Description provided by NIOSH]
• Subjects:
  Accidental Falls Accidents Biomechanical Phenomena Occupational Health Safety
• Keywords:
  Biomechanical Modeling Biomechanics Foot Protection Footwear Injuries Models Slips, Trips, And Falls STF
• Series:
  Grant Final Reports
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Final Grant Report
• Place as Subject:
  OSHA Region 3 ; Pennsylvania
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  OEP - Office of Extramural Programs
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-80
• NIOSHTIC Number:
  nn:20063125
• Citation:
  Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R01-OH-010940, 2020 Dec; :1-80
• Contact Point Address:
  Kurt E. Beschorner, Ph.D., University of Pittsburgh, Swanson School of Engineering, 4420 Bayard St #306, Pittsburgh, PA 15213
• Email:
  beschorn@pitt.edu
• Federal Fiscal Year:
  2021
• NORA Priority Area:
  Manufacturing ; Wholesale and Retail Trade
• Performing Organization:
  University of Pittsburgh
• Peer Reviewed:
  False
• Start Date:
  20150930
• Source Full Name:
  National Institute for Occupational Safety and Health
• End Date:
  20190929
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:a1ac9f1f16c8870de10925fe5ab2698a4f5e380334a29413534f37b7a4ce908d946545d14bb662ffbdce5c220a6263c98485daaf1787a30bd5a494a9cf6da4be
• Download URL:
  https://stacks.cdc.gov/view/cdc/219067/cdc_219067_DS1.pdf
• File Type:
  [PDF - 2.62 MB ]