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

Hybrid Surface Systems

There were a total of four sites with three different hybrid (HYB) surface systems evaluated in the study.  All three systems have been purposefully designed and marketed to provide an impact attenuating and accessible surface to accommodate both safety and accessibility.  One site used an outdoor carpet (HYB-A) over engineered carpet padding infilled with silicone sand.  Two sites used a system where the base consisted of 2 ft. x 2 ft. pillows filled with shredded rubber and covered by 5 ft. wide rubber top mats (HYB-B), resembling melted spaghetti, affixed at the seams similar to how carpet is seamed together.  The last site used an artificial turf grass system (HYB-C), similar to that used on football fields. The HYB surface systems ranged in cost from $7.50/sq. ft. to $12.65/sq. ft.

As tested within 12 months of installation, all three HYB surface systems were observed to have minimal deficiencies, comparable to the SDS with PIP.  The means for firmness, stability and the standard deviation were also comparable to the other unitary surfaces, PIP and TIL. 

The outdoor carpet (HYB-A) was installed by a professional contractor approved by the manufacturer.  The top layer outdoor carpet is laid over an engineered carpet pad. Silicone sand is filled in over the top carpet layer to contribute to its ability for impact attenuation.  The outdoor carpet installation comes in a variety of primary colors.  The surface system was purposefully selected by the owner as a pilot site to observe how the product would perform over time.  If it was deemed successful, the playground owner intended to use the product at other sites.  After 12 months of installation, the top layer carpet began to shrink and separate at the seams creating openings and changes in level greater than ½ inch.  Under the terms of the product warranty, the manufacturer returned to the site to make spot repairs where carpet remnants were inlaid at the widest gaps between the seams.  Through the fifth year of installation, the carpet layers have continued to shrink and separate at the seams.  Field testing for ASTM 1292‒99/04 was also conducted annually at the request of the playground owner.  Between years two and five, the HIC value at an 8 ft drop height went from 688 to 922.  By year five, one location was within compliance for ASTM 1292‒99/04 by less than 80 HIC.  The manufacturer has since gone out of business and the owner has been left with a product warranty that is now useless.

The rubber top mat system (HYB-B) was installed at one site entirely by the manufacturer.  Another playground owner chose to have its site installed by a combined crew of the manufacturer and park maintenance personnel.  There were no observable differences from the two installations within the first 12 months.  It was not until years three and four that the site installed entirely by the manufacturer started to show instances of separation at the seams.  The playground owner attributed this to the park maintenance personnel’s lack of knowledge for maintaining the surface system since they were not involved in the installation and did not have any other playground sites utilizing this surface system.  During year four, the playground owner requested training from the manufacturer on the specific methods to mend seams and patch sections.  By year five, the site showed improved attention to maintenance.  The site installed by the combined crew did not show any issues of surface deficiencies.  At this site, the originally planned surface was PIP.  Because of construction changes on site, the playground owner grew concerned at the increased cost for the PIP and decided to try the HYB-B as a pilot installation.  The park maintenance crew worked alongside the manufacturer to learn the process to install the surface base and top mat.  The playground owner was purposeful in this decision in order to avoid long term costs to bring the manufacturer to the site for repairs or instances where equipment might be added or moved.  The playground owner reports that maintenance personnel have grown in their knowledge working with the product and recently installed another playground utilizing the same surface system.

The artificial grass surface system (HYB-C) was installed by the manufacturer.  The two locations each have a different base.  The first site has an engineered carpet pad base and the top turf layer is filled in with rubber granules.  The second site has a base comprised of packed shredded rubber.  Neither site showed any measurable deficiencies during the first year of installation.  During year two, the second site began to show signs of traffic patterns.  These areas were not measurable with the digital level, however they should continue to be assessed over the life of the playground.  Heavy pedestrian traffic can cause the artificial grass to fall flat.  Both playground owners have planned for the manufacturer suggested maintenance.  The first playground owner purchased mechanical equipment to rake and fluff the grass.  The other playground owner brings a contractor back seasonally to do the same thing.  One issue this playground owner had not planned for was the build-up of static electricity.  During the second year site visit, the assessment team was unable to touch any of the metal playground support posts in a section of the playground without receiving a static charge.  The playground owner met the assessment team on site and reported the problem emerged at the end of the first season of use.  The playground owner contacted the manufacturer and was given a solution to apply to the surface to minimize the static electricity.  The playground owner reports at least three applications of the solution were required at the beginning of the season in order for the static electricity to dissipate.  The playground owner also reports disappointment with the manufacturer as this information was not shared with the owner during the time the system was being considered for purchase.

The playground owners for both HYB-C sites had included the requirement for third party testing for ASTM 1292‒99/04 as part of their purchase agreements.  As such, both sites were tested for impact attenuation by independent consultants following installation.  While both sites were found in compliance for ASTM 1292‒99/04, both playground owners have reported concerns for the HIC values at 8 ft drop heights and plan to closely monitor those locations.

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