Slip Fall and Floor Slip Resistance Testing -

Slips and Falls: The Complex Dynamics Behind Simple Accidents

Falls are consistently the leading cause of injury-producing accidents. They account for more than 1 million injuries each year in Canada and the United States.
Why are there so many falls?
In part, it is because we fail to understand the complexity of same-surface slip-and-fall accidents.
We assume that people fall because the floor is slick, because they are clumsy or careless, or because they step on a foreign object. These assumptions lead to investigations that are one-dimensional and to repeated accidents at the same location.
To understand causality and to determine responsibility for an accident, the investigator usually eliminates many possible causes.
The American Society for Testing and Materials and the National Bureau of Standards have studied the reliability of test devices for measuring the floor surfaces and the effect of cleaning materials on walking safety. We can now predict how a floor-care product will behave when applied according to a manufacturer's recommendations.
Floor characteristics are now measured in terms of the static or dynamic coefficient-of-friction(COF). Most common machines measure the coefficient-of-friction of a surface by dragging, pushing, or striking a floor area with a shoe material having a known surface characteristic. This coefficient can be determined by taking the drag necessary to first move the object and dividing it by the weight of the object being pulled. a floor with a COF of .5 or less is considered slippery; a floor with a COF of more than .5 is considered safe. 
The accuracy of the testing equipment has been validated by the National Bureau of Standards and other testing agencies. They provide the safety investigator a standard with which to compare a floor surface.
Routine Testing 
Modern materials and floor-care products are now considered safe and consistent, so builders and service companies no longer test each batch of a product. But this confidence can lead to problems.
A new shopping center in a tropical city, for example, used glazed ceramic tile in its walkway. A woman slipped on the tile and was hurt. The architect had specified an eight-inch strip of ceramic tile with a decorative pattern, and the builder presented the owner with samples. No one knows if the tile manufacturer had recommended the use of this tile on outside walkways, but it was a poor choice. When it rains, as it often does in this tropical city, the sidewalk becomes hazardous.
The static coefficient-of-friction has been measured at .30 on a wet day. In this case, a small number of tiles could have been tested under conditions similar to those in its expected use. The cost would have been minimal. But now the tile must be completely removed from the shopping center or temporarily fixed by applying an external finish. The removal will cost thousands of dollars.
Types of Floors 
The slip-resistance of floor materials has received considerable attention from safety investigators. There is a large body of knowledge about material characteristics. Each material has benefits and disadvantages, and each must be properly installed and maintained to produce a safe walking surface. 
As a rule, the slip-resistance of a floor material is directly proportional to the number of microscopic points that project from its surface. Concrete, for example, is a relatively safe surface, but if it is improperly cured when poured, it becomes a very slippery surface. 
Asphalt tile and vinyl tiles are relatively safe if the surface treatment chosen is correct. Marble and terrazzo surfaces are inherently slippery and should be treated with a sealer containing a high percentage of solids to increase slip-resistance. Floor tile can be very safe or very dangerous, depending on its factory finish and its maintenance.
Floor Finishes and Cleaning Methods 
A custodian's locker is a good place to start an investigation of slip-and-fall accidents.
The investigator should determine what products are being used and how they are being combined. Are the mops dirty? Does the staff use the same mop for cleaning and disinfecting? How often is the floor finish removed, and what is used to remove it?
A floor finish is a product that is put on top of the raw floor material to protect it, to beautify it, or to change its surface characteristics. A floor finish can be used to make an unsafe floor less slippery or can inadvertently be used to make a safe floor dangerous. Finishes can be either synthetic or organic.
Improper cleaning methods can complicate matters further. The National Safety Council reports that may slip accidents are caused by improper cleaning methods and recommends that floors be cleaned only with clean water. If soap or commercial strippers are used on a floor, care must be taken that no residue remains when the floor dries.
A final finish is sometimes applied to the floor by the pedestrian, who can pick up fertilizer and other chemicals on shoes and bring dangerous adherents into a building.