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

IV. Discussion of Findings and Implications

The most valuable lesson to be learned from this longitudinal study, it is that there is no perfect playground surface.  Even within 12 months of installation, each type of surface had some type of issue or series of issues that affected the product’s performance and contribute to the necessity and frequency of surface maintenance to assure accessibility and safety for use by children on a daily basis.  A playground surface with poured-in-place rubber had a use zone found in non-compliance with the ASTM standard for impact attenuation.  Playgrounds surfaced with tiles were observed with puncture holes, buckling and separating seams that created openings and changes in level on the accessible route.  Inaccessible routes with undulating surface material were identified at playgrounds with engineered wood fiber.  A build-up of static electricity was found at one of the hybrid surface locations.  Each occurrence and event was weighed and balanced with the product’s feature advantages and drawbacks. 

Findings

The evaluation of the 35 playground sites in this study has provided some important information on the design, installation, and maintenance of playground surface material for the accessible route in the use zone.  The information can serve as guidance to both future playground planning and priorities for future research.  The following are the predominant findings from this study:

• No single type of surface material/system was found to be the most accessible surface or better than others when comparing its ability to meet the accessibility standards with issues related to installation and maintenance.
• Within 12 months of installation, playground sites in the sample with the loose fill EWF were found to have the greatest number of deficiencies, such as excessive running slope, cross slope, and change in level, affecting the accessible route to play components.
• Within 12 months of installation, playground sites in the sample with loose fill EWF were found to have the highest values for firmness and stability, indicating greater work force needed to move across the surface, while playground sites with the unitary surfaces TIL and PIP were found to have the lowest values for firmness and stability– indicating less work force necessary to move across the surface.
• Deficiencies, such as excessive running slope, cross slope, changes in level, and openings for PIP, TIL and HYB began to emerge 24‒36 months after installation.
• Occurrences were identified in the sample where the surface material installation did not parallel either the manufacturer’s installation instructions or the procedural instructions on the laboratory test sample for ASTM F1951‒99.
• A playground surface with fewer accessibility deficiencies and a lower measurement for firmness and stability did not necessarily meet the safety standards for impact attenuation.Surface cost for material cannot serve as an indicator or predictor of performance.

There were also findings related to the design of the playground sites and with the selection of the specific playground surface materials or systems.  There were instances where the accessibility standards were not properly applied to the playground design.  For example, there may be swings designed to be on an accessible route and connected by the unitary surface.  However, the design may not have allocated for the 30 x 48 inch clear floor space to transfer at the swing or the required 60 inch diameter turning space adjacent to the swing.  While the design itself may be the problem in some cases, failure to collect enough information about the site was also identified as a likely contributor to installation of accessible routes not fully compliant with the standards.  Some playground designers and manufacturers do not necessarily consider the completion of a site survey as essential to the design and construction of the playground.  The lack of site surveys for at least three playgrounds in the study created installation errors along the accessible routes.  Each of the three sites were deemed “relatively flat” by their planning teams.  When it came time to install the surface, the lack of planning for the accessible routes caused the contractors to improvise for surfaces to meet up with composite structures and points of egress resulting in routes that exceed the maximum allowable running and cross slopes.  Lack of site surveys to plan effective drainage could also be considered as contributors to standing water, washed out sub-base stone, mold and vegetation growth.  Construction changes on site also negatively affected the accessible route affecting running and cross slopes, transfer heights and required clear floor space.

Installation

Surface materials/systems were installed by both contractors and the playground owners’ maintenance staff.  PIP was exclusively installed by contractors specializing in the surface material.  Participating playground owners believed the intensive installation requirements for PIP, from mixing the binder to troweling the material level, were best completed by contractors experienced with the surface material.  The intensive installation requirements also made it necessary for the contractor to return to sites for repairs due to vandalism or patches at locations where equipment may have been removed. The costs for return repairs or patches were dependent upon whether the project was covered under the warranty.  The most notable installation concerns were raised at sites where the PIP appeared in good condition, but when tested with the TRIAX did not meet the ASTM standard for impact attenuation.  The PIP surface at two swing bays for a new installation was found in non-compliance with HIC scores well over the 1,000 HIC allowable under the standard.  Had the playground owner decided not to utilize the field test for impact attenuation, they likely would not have learned of the product failure at the swings until well after the warranty had expired.  This example further illustrates the critical need for field testing immediately following installation and throughout the life cycle of the playground.

Other deficiencies for PIP were cited in areas where the granules from the top layer began flaking off within the first three years of installation.  This flaking condition has been linked to either inadequate ratio of bonding agent to granules when mixed on site; and/or failure of the bonding agent to properly cure when installed at 40 degrees Fahrenheit and falling.  The manufacturer installation instructions show the preferred atmospheric temperature for installation to be 40 degrees Fahrenheit and rising.  Left unattended over time, areas where the top granular layer has flaked away can lead to non-compliant clear ground space at play equipment such as swings, transfer systems and the egress of slides.  Deficiencies related to installation methods may not become evident for months or even years.  Thus, it is necessary for the playground owner to prepare for these situations prior to purchase through the terms of the warranty and/or specified funds for maintenance.

HYB-A (outdoor carpet) and HYB-C (artificial grass) were installed by contractors representing the manufacturers.  These surface systems required installers experienced with laying the sub-surface, adjoining seams, and affixing the surface material to the border.  Separation at the seams appeared to be the most prevalent concern following installation.  Repairs to seams must be made by the contractor and costs are dependent upon the terms of the product warranty.

Three playground owners selected TIL and HYB-B (rubber top mat system) based on perceptions that the surface systems would be easy for park crews to install and maintain, thus producing cost savings for the agencies.  The learning curve for installation of the TIL proved to be most challenging.  The first installation of the TIL was perceived as so difficult for the park maintenance crew that any cost savings was mitigated by the lengthy learning process.  By the time the playground owner had installed its fourth playground with TIL, the agency had decided to transition to a different surface. On the contrary, another playground owner that contracted the TIL installation to a preferred manufacturer’s installer was very pleased. They cited the ease for their park maintenance crew to replace a tile here or there as a primary reason to continue use of the TIL.  The playground owners using HYB-B reported the surface system was easy to install and maintain once their park maintenance crews received sufficient training from the manufacturer.  One of the playground owners using HYB-B had gone on to install their second playground site with no issues or complaints.

EWF was most frequently installed by park maintenance crews and perceived as relatively easy compared to other surface materials.  Sites installed with EWF were found to have the highest SDS within the first year of installation including deficiencies with excessive running slope, cross slope and change in level.  Upon further inquiry with the playground owners, it was found that none of the owners were aware of EWF manufacturers’ recommendations for installing the material in layers, applying water and compacting each layer.  The lack of EWF particle compaction and layered installation is considered the major contributing factor leading to undulation within the surface area at the participating playground sites. Since this information has been shared with the playground owners, many have begun to rethink their approach to EWF installation.  One of the playground owners transitioned to installation where the EWF is delivered by truck and blown into the sites by a contractor as opposed to traditionally dumped, shoveled and raked by their maintenance crew.  The playground owner believed there to be better control of the depth and reach of the blown EWF.  However, they did not consider it to be a cost savings.  The park maintenance crew was still required to level and compact surface areas where they believed the EWF delivery crew had not done a satisfactory job of achieving an accessible route and level transitions between the EWF and PIP.  Other playground owners are considering the installation of EWF as an opportunity to use volunteers to assist in compaction by running drum roller teams across the surface area.

Maintenance

Maintenance is one of the greatest factors affecting the accessibility of the surfaces in the sample.  There was a lack of installation/maintenance information provided by the manufacturer to the playground owner prior to purchase and there was a steep learning curves related to working with various surface systems. Each of the 16 participating municipalities had maintenance personnel trained through the either the National Playground Safety Institute (NPSI) or the Illinois Park District Risk Management Association (PDRMA).  The participating agencies recognized maintenance as a critical need in order to provide a safe environment for the public to recreate.  All of the municipalities had “playground crews” responsible for visiting each playground site, making visual inspection of the area, collecting trash, and completing repairs as needed.  The playground crews ranged in number from 1‒3 staff, usually with one full-time employee and 2‒3 seasonal staff during the summer months.  At least 30 minutes was spent on site.  However, the frequency of visits to each site varied among the different agencies.  Large playgrounds at regional parks and sites where programming occurred were most often visited.  Some were visited daily during peak summer months.  Smaller neighborhood parks may have been visited 1‒3 times per week or two times per month.

Surface deficiencies were found to exist at each site regardless of the frequency of visits by the playground crew.  Any correlation between the frequency of maintenance and the SDS was inconclusive.  However, over the course of the longitudinal study, the research team found that where the playground crews became more engaged in the study, the maintenance specific to accessibility began to improve.  This finding was most evident at sites visited in 2012, the final season of data collection.  A marked improvement in SDS was noted at sites where playground owners had become more fully engaged in the study.  They participated in two conference calls for study updates, made inquiries, and/or participated during research team site visits to gain greater understanding of the assessment process. At least three EWF sites had improved SDS where the surface material was observed as more level and better compacted than previous site visits.  One site utilizing PIP as the primary access route and EWF as the secondary access route was assessed with less than 1 percent slope at the transition between the two surface materials.  This was observed as the most improved and maintained transition between surface materials of the sample.

PIP was recorded as the surface material requiring the least instances of maintenance.  Maintenance areas were noted where the surface had cracks, buckles, openings or a granular layer had worn away under high traffic areas like swings, transfer steps and the egress at slides.  While PIP had the least instances requiring maintenance, it is still notable because the surface repairs can be extensive.  Repairs must be done by either the original installer or professional certified by the manufacturer resulting in added costs.  The patch repairs also necessitate cutting away a larger section of surfacing in order to fill and level the deficient area. 

A greater number of TIL sites were recorded in need of maintenance than originally hypothesized.  TIL deficiencies included punctures holes ranging from .50 inches to more than 2 inches in diameter; and instances where the seams had started to shift or buckle creating openings and changes in level along the accessible route.  The playground owners reported mixed opinions on continued use of the TIL systems.  The playground owner that had invested the most, both in material and staff training, had the highest number of surface deficiencies requiring maintenance.  After five years of use, the playground owner decided to go with a different unitary surface system.  Yet, a neighboring playground owner who had the surface installed by a contractor, only had to replace one tile during the study.  The playground crew reported the replacement of the tile took two people less than an hour and it was relatively easy. The contrasting experiences of the two agencies could be as simple as products supplied by two different manufacturers.

EWF sites were recorded in need of maintenance most frequently and earliest in the study.  As has been mentioned previously, maintenance issues were most needed to correct accessible routes and clear ground spaces where the running slope and cross slope exceeded the accessibility standards.

Findings from the study illustrate the critical need for maintenance, regardless of the type of surface material used for the accessible route.  It is essential for ongoing maintenance from visual site inspections to patch repairs or material replenishment be planned at the conception of the new playground project.  Further, the maintenance crew should be trained in both playground safety and the accessibility requirements to ensure ongoing compliance with the standards.

Implications

The qualitative data from the on-site inspections support the perceived advantages and disadvantages of the unitary and loose fill materials as described in the literature review.  The initiation of the surface deficiency score can quantify where the surface samples fail to comply with the standards for slope, cross slope, vertical change in level, or openings in the surface.  Further, the measurement of firmness and stability can serve as an indicator of the variable characteristic of the surface sample. 

Lack of playground sites with shredded rubber for participation in the study prohibited collection of quantitative and qualitative data regarding the accessibility of this loose fill surface material.  The recycled shredded rubber industry, over the last five to eight years, has positioned itself as the provider of a “green,” environmentally friendly product that is safe and accessible.  As such, there is a marked absence of public data as to how this particular type of surface material would compare to PIP, TIL, EWF and HYB.  Comparison of shredded rubber with the only other loose fill surface material in the study, EWF, could not be made.  There are no data to show how the two surface materials compare to one another or how the two surface materials in the category of loose fill would compare to the category of unitary surface material. Without descriptive statistical analysis of the firmness and stability of shredded rubber as a playground surface, playground operators do not know how the material will perform over time in the field.

Proper installation in accordance to the manufacturer’s instructions, per the standards, and by experienced personnel is critical.  Sites where the various surface materials have been installed by park personnel with limited experience on the installation procedures, ASTM specifications, and accessibility standards were reported with deficiencies within 12 months of installation.  It is critical for the installation crew to fully understand and adhere to the manufacturer’s instructions, less the terms of the warranty be rendered null and void.

Visual inspection alone cannot determine if the playground surface is accessible and impact attenuating in accordance with the ASTM standards.  The discovery of areas in the sample where the surface was found in non-compliance for ASTM F1292‒99/04 impact attenuation was alarming for both the research team and the playground owner based on the beautiful appearance of the newly installed surface, the cost for the surface and the assumption that it was installed with the specific intent of minimizing injury for children using the play equipment.  A playground surface may have few to no identifiable deficiencies specific to the accessibility of the route, however, this does not have any relation to whether the surface has the ability to absorb the impact from a child’s fall per the safety standards.  Field tests for compliance with ASTM F1292‒99/04 must be conducted following installation and be part of an ongoing maintenance routine to ensure the integrity of the safety resilient surface system. 

There needs to be a portable field instrument to determine compliance for ASTM F1951‒99.  The current test protocol is designed for a laboratory environment and the cost for the equipment to measure the work force of the manual wheelchair moving across the surface is upward of $20,000.  The cost is prohibitive to playground owners and contractors that need to confirm the surface material has been properly installed and maintained to the same specifications the sample was tested and certified to ASTM 1951‒99 in the lab.  For the purpose of this study, the Rotational Penetrometer was used as the field instrument to measure firmness and stability in lieu of the costly equipment for ASTM F1951‒99.  Documented research has shown the Rotational Penetrometer to have a high degree of repeatability and reproducibility (ASTM, May 27, 2005; ASTM, September 2010). ¹

PIP and EWF represent the most diverse characteristics of each category in this study.  Findings from this study provide expanded knowledge on the objective measurement of firmness and stability along with the variability of the material characteristics contributing to the accessibility of the surface.  The measured values for firmness and stability, standard deviation and the sum of the values illustrate the variability of the material characteristics and composition.  If manufacturers reported the average values for firmness and stability, similar to the ASTM requirement to provide laboratory test results for the critical fall heights of the surface sample, playground owners could gain a better understanding of the variability of the surface material and select a surface material more appropriate to their agency resources for installation and long-term maintenance.  However, again, to ensure consistency, repeatability and reproducibility, an ASTM field test protocol is critical.  Published information on the correlation between the surface material’s firmness and stability in relation to the frequency of non-compliance with the accessibility standards for running slope, cross slope, changes in level and openings, could create a greater awareness among playground owners and positively influence their purchasing decisions and maintenance practices.  If the playground owner had a better understanding of the values measured with the Rotational Penetrometer, they might also be better equipped to establish an installation baseline and maintenance targets for the surface material.

Data on the performance of the hybrid surface systems may be promising enough to lead to further research and product development as the next generation of accessible protective playground surfacing.  Although, much more research needs to be conducted among all three brands of hybrid surfaces in this study to evaluate the longevity for impact attenuation, durability for high public use, resistance to vandalism, and ability to withstand various outdoor climates.  Product development in this category of hybrid surface systems, where there is some type of loose fill base covered by a unitary mat, could eventually provide a more middle ground in terms of costs and overall performance if the data on longevity and durability are made available up front for the playground owner prior to the decision to purchase.

¹ Results of interlab studies determining the repeatability and reproducibility of the Rotational Penetrometer were reported through work items of the ASTM F08.63 Subcommittee on Playground Surfaces.  For more information, contact ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA, 19428-2959.

Conclusion

Preliminary results from this study indicate that there is no perfect playground surface.  Even within 12 months of installation, each type of surface had some type of issue or series of issues that may affect the product’s performance and contribute to the necessity and frequency of surface maintenance to assure accessibility and safety for use by children on a daily basis.  The public playground has the potential to provide immeasurable opportunities supporting the development of children of all abilities.  The design, installation and maintenance of play equipment and the surface material is critical to achieving an inclusive environment that facilitates child development and enables children with disabilities to fully participate with their non-disabled peers.  Failure to recognize the significant role of the surface material is to design for segregation.  Where the playground surface material fails to comply with safety standards for impact attenuation, children are put at risk of injury.  Where the playground surface fails to comply with the minimum accessibility standards, children with mobility impairments may be regulated to the sidelines only to look on. 

Playground owners need to become educated on, not only the minimum safety and accessibility standards, but the practical application of the standards to the newly installed playground surface in order to inspect the surface and ensure it is compliant.  To fully benefit from the product’s marketed advantages and costs-savings, decision-makers should request much more information from the manufacturer including specific instructions for installation and maintenance along with results of laboratory tests and surface preparation for the lab tests that are consistent with the installation instructions.  Decision-makers should dialogue with the surface supplier regarding realistic, objective measurements to evaluate surface performance and maintain the surface material over the life span of the playground. The communication gap between the manufacturer’s literature and the owner’s perception of installation and maintenance must be bridged if the owner is to fully benefit from the available products on the market today.