There are several commonly used devices and techniques for measuring the slip resistance of floors. However, some methods or techniques used with these devices may provide misleading information that does not represent actual conditions. This paper demonstrates why measuring in the direction of travel is critical when evaluating the slip resistance of floors, particularly when applied to slip/fall litigation.
This paper also explores how normal surface wear on vinyl tiles affects slip resistance measurements. Statistical comparisons were made between wet and dry tiles both with and against the direction of travel. Tiles included new, unused tiles that were tested in a laboratory environment and actual in-use tiles. Normal wear and tear can produce highly directional scratching on flooring surfaces, particularly in long halls that have few corridors or doorways present. There are statistically significant differences in coefficient of friction measurements given the direction in which slip measurements are made. Interestingly, the coefficient of friction is higher against the typical direction of travel when conditions are dry, but lower against the typical direction of travel when conditions are wet. Therefore, when evaluating the slip resistance of floors, particularly when recreating an accident scenario, it becomes very important to know the direction the person was traveling when they fell in addition to whether or not the floor surface was wet and/or covered with other contaminants.
The device, techniques, and evaluation methods used can fundamentally bias the determination of surface slip-resistance values. This may result not only in courtroom bias, but serve as an impediment to improving slip/fall safety in a facility.
Each year, more than one million people are injured in slip, trip, and fall injuries each year and over 16,000 people die from falls (National Safety Council, 2000). Many consider falls in the workplace to be the number one preventable loss type (DiPilla, 2001). In order to take effective action to minimize slip and fall accidents both in the workplace and in public venues, the actual slip-resistance of these surfaces must be characterized.
Slip resistance is not the same as the static coefficient of friction, which is a measure of the friction force necessary to initiate a motion between two stationary objects. The contact surfaces (shoe and floor) are moving with respect to one another and not initially static. Actual slip resistance is a function of the walking surface, footwear, and the presence of contaminants. Slip resistance measurement, therefore, is a function of both the surface tested and the system used to test the surface. The individual's gait dynamics (how they walk) plays a role as well. When approaching a known slippery surface, a pedestrian can alter their gait to safely negotiate a slippery surface. For example, it is possible to "walk" across an ice rink. However, an unexpectedly slippery surface, even if just slightly different from the preceding surface, may result in a slip, fall, or injury. For example, walking across a freshly mowed lawn and encountering an "over-watered," slippery section.
