Predicting slips based on the STM 603 whole-footwear tribometer under different coefficient of friction testing conditions

Abstract

Assessing footwear slip-resistance is critical to preventing slip and fall accidents. The STM 603 (SATRA Technology) is commonly used to assess footwear friction but its ability to predict human slips while walking is unclear. This study assessed this apparatus’ ability to predict slips across footwear designs and to determine if modifying the test parameters alters predictions. The available coefficient of friction (ACOF) was measured with the device for nine different footwear designs using 12 testing conditions with varying vertical force, speed and shoe angle. The occurrence of slipping and the required coefficient of friction was quantified from human gait data including 124 exposures to liquid contaminants. ACOF values varied across the test conditions leading to different slip prediction models. Generally, a steeper shoe angle (13°) and higher vertical forces (400 or 500 N) modestly improved predictions of slipping. This study can potentially guide improvements in predictive test conditions for this device.

Practitioner Summary: Frictional measures by the STM603 (SATRA Technology) were able to predict human slips under liquid contaminant conditions. Test parameters did have an influence on the measurements. An increased shoe-floor testing angle resulted in better slip predictions than test methods specified in the ASTM F2913 standard.

Keywords:

• Coefficient of friction
• required coefficient of friction
• slip-resistance
• slips
• trips and falls
• footwear testing

Acknowledgements

Some custom footwear was provided by Timberland^®.

Additional information

Funding

This work was supported by the National Institute for Occupational Safety and Health under grants [R01 OH007592, R01 OH008986, and R01 OH010940]; by the National Institute on Aging under grant [R44AR064111]; by the National Center for Research Resources under grant NCRR [S10RR027102], and by the Saf-Gard Safety Shoe Company^® under grant [0049178].