A Longitudinal Study of Playground Surfaces to Evaluate Accessibility - Final Report

Poured in Place Rubber

Nine were surfaced entirely with poured in place rubber (PIP), while five sites were combined with engineered wood fiber (EWF).  The surface cost for PIP ranged from $6.59/sq. ft. to $19.80/sq. ft.  The wide range of cost per sq. ft. can be attributed to the fact that PIP is often sold on a sliding scale, the more material purchased, the cheaper the unit cost.  The cost for PIP has also been dramatically affected over the last five years due to volatility in the petroleum market.

Within the first 12 months of installation, the sites surfaced with PIP did not have any recorded locations where the surface samples exceeded the accessibility standards for slope, cross slope, changes in level or openings.  The mean for the surface firmness and stability was well under .50 inches.  From the “looks” of the surface locations, they appeared to be very accessible within a 12 month period from installation.  However, a major concern was discovered at one of the test locations where the playground owner opted to also have the surface tested for impact attenuation and compliance with ASTM F1292‒99/04.  Various locations on site were tested using the TRIAX to record GMAX and HIC.  The maximum values allowable by the standard are 200 for GMAX and 1,000 for HIC.  Drop heights from composite equipment up to 8 ft. high passed the field test.  But it was the PIP surface at two swing bays that was found in non-compliance with HIC scores well over the 1,000 HIC allowable under the standard.  The playground owner used the terms of the warranty and purchase order as a binding agreement requiring the manufacturer, at its own expense, to return to the site and repair the surface installation.  Approximately 2,000 sq. ft. at the swing bays was resurfaced to add more depth to the PIP.  When the surface area was retested with the TRIAX, the HIC ranged from 650‒750 at the swings, well under the 1,000 maximum allowable by the standard.  Had the playground owner not discovered the non-compliant surface area until after the warranty had expired, it would have cost the agency in excess of $35,000 to correct the surface area serving four swings.  During the course of the longitudinal study, at least two additional playgrounds surfaced with PIP were found in non-compliance with ASTM F1292‒99/04.  In each case, the playground owners required the installers to return to the site to make corrective actions.

Between 24‒36 months, locations surfaced with PIP began to show signs of cracking and instances where the top layer of surface had worn off under the swings, slides, or other equipment with rapid motion.  At one such site, the top granular layer of PIP began flaking off in 1‒4 inch sections throughout the surface area, not just high traffic or rapid motion areas.  As it turns out, the surface material at this site was not installed per the manufacturer’s recommendations.  The installation occurred in the late fall when the temperature was 40 degrees Fahrenheit and falling.  The manufacturer installation instructions show the preferred atmospheric temperature for installation to be 40 degrees Fahrenheit and rising.  The error in installation is attributed to the contractor and pressure to stay on schedule as the construction season came to a close for the winter.  The playground owner insisted upon corrective measures.  Another contractor was brought in to apply a top binding coat.  This cost was absorbed by the sales representative.

As previously noted, two sites were installed as one layer comprised of bonded large particle rubber shreds.  This type of installation is a break from the traditional product known as PIP and consisting of two layers, a wear layer with larger rubber particles and a custom top layer with granular particles.  These two sites were assessed with locations throughout the playground where the large particles had separated from the bonded layer in chunks.  This was notable in areas such as the swings and teeter totters.  Particles were also separated from the bonded layer by the turning movement of the wheel on the Rotational Penetrometer during the site assessments.  Under the terms of the product warranty, the playground owner required corrective action where the damaged sections were cut out and patched with new material.