With regard to new playground safety surfacing and synthetic turf fields, we are often asked: “What should the Gmax and HIC levels be at installation?”
Guidelines for ensuring a safe surface is installed:
1 – Your specification must address validation testing after the installation is complete, regardless of the performance you require. We have seen several Poured In Place pads fail because they were poured 1/4″ to 1/2″ thinner than specified.
2 – Provide some buffer between your required performance at the time of installation and the maximum allowable performance during the life of the product. Gmax/HIC examples that we have seen include 160/700, and 175/850.
“The surface will be tested 14-45 days following the installation. This shall be considered part of the bid amount. The results of the test shall yield a Gmax less than 160/175/200, and a HIC less than 700/850/1000. “
We advise communities and architects to set the allowable Gmax and HIC levels of their new surface below the maximum allowed levels of 200 and 1000. We feel this is sensible given that surfaces change over time and that there are known errors associated with measuring Gmax and HIC. Each community and their architect must determine what they consider the appropriate level for a newly installed surface.
Note: At the time of writing this (Jan 2017), ASTM has been in the process of debating the merits of greatly reducing the allowed Gmax and HIC levels throughout much of 2014 and 2015. Proposals have been as large as lowering GMax to 125 and the HIC level 700.