Slip Testing

Slip testing of surfaces is utilized when a slip and fall accident is investigated.  For this purpose, we utilize a variable incident tribometer, the English XL, to determine the traction provided by a walking surface.  This tribometer mimics the action of the human heel striking the ground while walking, and can be equipped with different testing feet/soles, including actual pieces of the footwear worn by those involved in the slip and fall incident.  The tester is highly mobile and can be taken to the actual location of the slip and fall where other environmental conditions can be reproduced and tested as well.  Examples of common contaminants in slip and fall incidents are liquid spills in retail facilities, and particularly water or grease spills in restaurants, to name but a few. 

With respect to the slip tester, it is crucial that the slip testing is performed with a machine such as a variable incident tribometer, where the traction on the surface is tested in a dynamic way.  Most traction testers employed today are essentially "drag sled" testers, where a piece of sample material of footwear is applied to the bottom of the machine and placed on the surface, a load is applied to the side of the sample, and a friction value is recorded based on the force required for the sample to begin sliding along the surface.   This method of testing has been shown to be highly inaccurate on anything other than dry substrates, due to "sticktion" created by water and other possible liquid contaminants.  Sticktion is a result of the tension between the water, the surface and the tested material, and will actually increase the resistance of the tester to sliding, hence giving false high traction values!  Clearly, a wet surface at almost all times has lower traction (in other words making it more slippery) than a dry surface, not less, as is often the inaccurate result of drag sled tests.

Refer to our Slip and Fall Incidents page for more info on these issues.

Case Study

FDi was recently retained to use the tester in a pro-active investigation a public pool, where the tile flooring around the pool deck area and in the bathrooms was elevated, and found to be notably slippery even to bare feet.  Numerous alternative solutions were tested before a satisfactory grooving technology was accepted, which has since proven to be an effective anti-slip treatment.