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Nelson & Associates :: Premises :: Coefficient of Friction Testing

The Causes and Prevention of Slip-Type Falls

Select Definition of Terms Pertaining to the Measurement of Coefficient of Friction

On wet surfaces, the slipperiness (slip index) of a walking surface is a function of the ability of the surface asperities to penetrate the hydrodynamic squeeze film. That is, the potential for heel-slid that produces the most common disabling fall on smooth surfaces is controlled by installing a walking surface having asperities sufficient to penetrate the hydrodynamic squeeze film and arrest the sliding tendency by engaging the shoe bottom. The sharpness of the asperities is the primary factor in slip resistance.


n., pl. asperities

Source: The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2000 by Houghton Mifflin Company.

Hydrodynamic squeeze film

Adhesion and Sticktion

Static Coefficient of Friction (SCOF)

Dynamic Coefficient of Friction (DCOF)

Slip Resistance

Slip Index


Reference: Unless otherwise indicated, the above material is cited from English, William, Pedestrian Slip Resistance – How to Measure It and How to Improve It, 2nd Edition, 2003.

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