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TESTING SYNTHETIC TURF SURFACES By Arthur Eddy, ASLA, LEED AP
As
we approach the fall season, athletics is gearing up for the long fall season, so this is a good time to start to discuss testing synthetic turf surfaces. Testing gives a field manager an understanding of how the surface is performing and what maintenance procedures should take place to ensure a field is performing and safe. Both safety and performance are equally important and should be part of an annual routine. In this article we will focus on some safety tests that will help to limit the exposure of a facility and keep athletes safe: GMax: The most common field test on a synthetic surface is GMax. GMax is the measurement of the hardness of the surface or the impact an athlete’s head will have with the surface. The harder the surface or the higher the GMax, the more critical the impact can be on the athlete. The softer the surface or the lower the GMax can reduce the impact. Reducing the GMax can reduce a player’s probability of a head injury, but care should be given to not make a field too soft which will impact other tests outlined below. GMax of a natural grass field is typically 75-115 G’s. The NFL has instilled a concussion protocol limit for critical injury of 165 G’s and the American Society of Testing Materials (ASTM) F1936-19 has a limit of 200 G’s. Head Injury Criteria (HIC): Similar to GMax, Head Injury Criteria is an effective way to measure the probability of a head injury to a player. The difference between GMax and HIC is the means in which the test is conducted. A spherical apparatus is dropped on the surface that mimics the form of a human head. Measurements are based on critical fall heights that measure hardness and softness of the surface and at which height there would be a critical injury to the athlete. The World Rugby association has a critical fall height of greater than 1.34 meters.
Ball Drop Testing Photo credit: Sportlab USA
Rotational Resistance Testing Photo credit: Sportlab USA
12 • New England BLADE • September 2021
