SHOCK ABSORBING, WHEELCHAIR ACCESSIBLE, RECREATIONAL SURFACE AREA AND METHOD OF CONSTRUCTING SAME

Abstract

A recreational play area meeting a fall height requirement and being constructed essentially of one or more layers of shock absorbing synthetic material such as dimpled polystyrene, running to a perimeter structure consisting of nailer boards and collector drain. The shock absorbing layer is overlaid with polyethylene synthetic turf filled with a sand/rubber mixture for added shock attenuation.

Description

FIELD OF THE INVENTION

This invention relates to recreational play areas and more particularly to a recreational play area with shock-absorbing qualities for fall-caused injury protection constructed by laying one or more layers of shock-absorbing material over a base such as asphalt, concrete or dirt. The shock absorbing layer or layers are then overlaid with synthetic turf to provide a natural appearance, as well as high durability and low maintenance requirement. The surface is also wheelchair accessible in that it provides a surface which is uniform and low-friction.

BACKGROUND OF THE INVENTION

Recreational areas, such as playgrounds and/or playscapes, have traditionally been characterized by dirt or turf surfaces which provide only minimal protection against injury due to falls. More recently, it has become popular to spread shredded rubber on the recreational surface area, around and under swings, slides, climbing bars and other recreational equipment. The principal purpose of such shredded lubber is to provide shock absorption to reduce the risk of injury associated with unintended falls.

These are significant disadvantages associated with the use of loosely spread particulate or shredded rubber. For one, the material is almost totally lacking in aesthetic value. It is also difficult to travel in wheelchairs, scooters and similar devices for the handicapped due, in large part to its irregularity and high resistance to wheel travel. In addition, it provides relatively poor traction. Further, the shredded rubber tends to get moved around; i.e., the area at the base of a slide or an area immediately under a swing is repeatedly contacted by children's feet and the shredded rubber is pushed away until there is little or no shock absorbing material in a critical area. In other areas, it gets piled up. The shredded rubber can be redistributed by raking but this requires regular maintenance, particularly after days or even hours of heavy use.

In my co-pending application Ser. No. 11/732,298 filed Apr. 3, 2007 and assigned to The Shane Group, I describe a fall-safe play surface using poured-in-place technology, the depth of the poured material being selected to meet a fall-safe requirement or standard. The poured layer is covered with synthetic turf.

SUMMARY OF THE INVENTION

In accordance with one aspect of my invention, a shock absorbing, fall safe, uniform recreational play surface area is provided by laying one or more pre-fabricated layers of sheet-like shock-absorbing material over a base; i.e., the desired fall height safety function is met by selecting the number of layers of material rather than by pouring. This greatly simplifies the installation procedure and eliminates the need for mixing and pouring materials. The shock attenuating material layers are usually sold in rolls which are relatively easily transported and which may be joined to one another by taping seams. The area is defined by a base which may be natural or constructed of concrete or asphalt. Because of the uniformity of the surface, it is easily wheelchair accessible and low in maintenance.

In accordance with a preferred embodiment of the invention, a collector drain is created around at least part of the periphery of the play area. At least one ply or layer of thin impervious polymeric material is then placed over the base so as to extend to the collector drain, the area preferably being sloped or grated toward the collector drain. The impervious layer is then overlaid with at least one layer of shock attenuating material which is then topped with a synthetic turf of wear-resistant polyethylene or the like. The turf may be filled with a mixture of sand and rubber to provide additional shock protection.

According to a second aspect of the invention, a method of constructing a recreation surface area over a base is provided. In accordance with the method, the base area is leveled or graded slightly toward a perimeter for drainage purposes. At least part of the perimeter may be defined by the construction of a collector drain filled, for example, with stone and containing a run of perforated drain pipe. The defined area is then optionally overlaid with a thin sheet of impervious; i.e., waterproof, polymeric material to promote drainage to the collector drain. Thereafter one or more layers of shock attenuating material are laid over the area and the seams, if any, are taped. Additional layers may be used where higher equipment is to be installed. The total thickness of material may be selected to meet a standard such as ASTM 1292-04. Thereafter, a layer of synthetic turf is placed over the impervious layer or layers. The turf may be partially filled with a granular mixture of sand and rubber.

BRIEF SUMMARY OF THE DRAWINGS

The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views and wherein:

FIG. 1 is a perspective view of a recreational play area which is constructed in accordance of the invention and on which typical playground equipment is installed; and

FIG. 2 is a sectional view of an illustrative construction illustrating a collector drain.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT

Referring to FIG. 1, there is shown a recreational or playground surface area 10 having a perimeter 12 which is essentially rectangular with right angle intersections; only a portion of the perimeter 12 is shown. Outside of the perimeter 12, the recreational area 10 is surrounded by natural turf 14; within the recreational area 10, the topmost surface is a partially filled synthetic turf 16 as hereinafter described in detail. The rectangular shape of area 10 is merely illustrative as virtually any shape may be created.

As is typical, playground equipment including a slide 18 and a spring-mounted children's riding creature 20 are installed. The slide 18 may have a height from about 3 to about 7 feet, the higher height slides recommending requiring a higher fall height safety factor than would be associated with the lower mounted children's riding creature 20.

Referring to FIG. 2, a vertical sectional view along perimeter 12 illustrates in detail the vertical structure of the recreational area 10 and the manner in which it meets the adjacent area of natural turf 14.

The first step in the construction method is to define the area and to prepare a substantially level surface on a suitable base which may be dirt, asphalt, concrete or other stable material. The base surface is preferably prepared in such as way as to be nearly flat but graded with a slope of between 0.5 and 1.0% toward the perimeter 12 for drainage purposes from the interior area 10 toward the perimeter. A very large area with only natural perimeter boundaries may be graded from the center outward. Other areas may be graded in only one or two directions, particularly is they are located on a sloped section of ground and/or abut a natural boundary such as a wall or sidewalk.

The next step is to define at least a partial perimeter. The first step, which is sometimes optional, is to build a collector drain 26 which involves trenching below grade. More detail is provided below. An accompanying step is to lay into the base 22 a nailer strip 24 which, in this case, comprises a line of pressure treated 2 inch by 6 inch nailer boards laid end-to-end along and immediately within the interior side of the perimeter 12. A flat, continuous surface must be prepared for the boards. The use of these nailer boards naturally suggests a play area shape defined by straight lines but which may have jogs or corners as is necessary to accommodate other natural or manmade features in the play area. In addition, the perimeter constructed in accordance with this specification may be only partial and may be integrated with other natural perimeter features such as walls, buildings, waterways or sidewalks. Plastic nailer strips may also be used. In any event, the perimeter is flush with adjacent turf and presents no obstacle to wheelchairs and the like.

The collector drain 26 is approximately 20 inches deep and is lined with a filter fabric of woven polypropylene filaments forming a stable and durable network. This material is readily permeable to water, non-biodegradable and resistant to soil chemicals, acids and alkalis. It is commercially available in rolls.

The drain trench 26 is filled with natural or crushed stone 32 and contains perforated pipe 30 to convey water to a storm sewer or an adjacent waterway or a so-called French drain or simply a reservoir or ditch. The collector drain is then filled with washed natural and/or crushed stone with an average size of approximately ¾ inch.

The perimeter-defining nailer boards 24 are then placed along the side of the collector drain around as much of the perimeter 12 of the recreational surface as is required. While wood boards are satisfactory, other materials such as plastic may be used.

The next step is to place over the base a continuous layer 34 of impervious, thin polymeric material, typically referred to as a “geomembrane” which is approximately 20 mils in thickness. This layer 34 comes in rolls and is laid over the entirety of the surface area and spliced by tape as necessary. It runs over the nailer board 24 and is secured thereto by nails 46 which also runs through a restraint strip 48 for purposes hereinafter described. The strip 48 may be plastic and has an L-shaped cross-section. The geomembrane 34 is optional.

The next step is to overlay the impervious layer 34 with one or more layers of shock absorbing, synthetic material layers 36, 38, 40, 42, the bottommost layer 36 extending partially over the collector drain 26 as shown and fully over the nailer board 24. A spike 44 or similar fastener is used to secure the lowermost layer 36 to the nailer board 24. In this case, four layers of shock absorbing/attenuating material are shown giving a fall height safety factor of over 8 feet. Each layer is approximately ¾ inch thick and, although it may be of varying construction, is preferably itself a multilayer structure of which the center core is 42 mil polystyrene with conical dimples numbering approximately 325 per square foot. The dimples are ⅜ inch in diameter at the based and 5/16 inch in diameter at the top and the tops of the dimples are flat. The outer layers which sandwich the polystyrene sheet are nonwoven, polypropylene fabric glued to the tops of the dimples as well as to the bottom surface of the center core. These materials, along with the impervious layer 34 also help to convey water horizontally from the play area up the field to and beyond the collector drain 24. The layers 38, 40, 42 edge immediately up to and are held in place by the edge restraint strip 48 as shown.

Next, the entirety of the topmost layer 42 is overlaid with synthetic turf 16 which is preferably partially filled with a sand/rubber particulate material 49 to act as a ballast layer and also contribute to the shock absorbing character of the overall structure. A preferred synthetic turf is Radicci 69 oz. polyethylene and SF1 polypropylene with a pile height of about 1¾ inch and a weight of about 10 lbs. per linear foot in a 15 foot width. Seams are taped during installation.

As shown in FIG. 2, a surrounding area of natural turf 14 is graded to be essentially flush with the fill of the synthetic turf 16 at the perimeter 12 so as to create a natural integration or flow from the synthetic turf 16 to the natural turf 14.

In accordance with the invention, the number of layers of shock absorbing material may vary from one to four or more as required by the fall height requirements or standards or recommendations associated with the equipment on the recreational surface 10. The base surface may, as described above, be of any of a number of suitable materials or combinations thereof. The grading may be accomplished by scraping a natural surface area down to a base layer or by simply flattening or preparing a base layer and grading the surrounding area of natural turf 14 up to it. The entire base may slope in one direction toward a collector drain or may be highest in the center and slope in all directions toward a surrounding perimeter 12. All synthetic materials used in the surface are completely recyclable. These and other variations will be apparent to those skilled in the art.

Claims

1. A method of constructing a recreational surface area over a stable base comprising the steps of:

defining a perimeter of the area;

overlaying the area with one or more layers of shock absorbing synthetic sheet material to a thickness providing a fall height safety factor for the area; and

overlaying the shock absorbing material with synthetic turf.

2. The method defined in claim 1 wherein the step of defining the perimeter includes the installation over the base of a nailer strip and overlaying the area with a thin impervious membrane.

3. The method defined in claim 2 including the further step of securing the impervious membrane to the nailer board strip.

4. The method of claim 1 further including the step of building a collector drain in the base along at least part of the perimeter.

5. The method defined in claim 4 wherein the step of building a collector drain includes forming a trench, placing a perforated drain pipe in the trench and substantially filling the trench with stone.

6. The method of claim 2 including the further step of securing an edge restraint to the nailer strip immediately adjacent the outer edges of the shock absorbing material.

7. The method of claim 4 wherein the shock absorbing material comprises multiple layers and the bottommost of said multiple shock absorbing layers partially overlies the collector drain.

8. The method bf claim 1 wherein the base is graded toward the perimeter.

9. The method of claim 1 including the further step of filling the artificial turn With a granular mixture made up of sand and rubber.

10. The method of claim 1 further including the step of grading the area around and outside of the perimeter with top soil and natural turf to be essentially flush with the synthetic turf overlying the area.

11. A shock absorbing recreational surface constructed over a stable, substantially flat base layer comprising:

a base;

at least one layer of shock absorbing synthetic prefabricated sheet material overlying the base; and

a layer of synthetic turf overlying the layer of shock absorbing synthetic sheet material.

12. A recreational surface area as defined in claim 11 wherein at least part of the area perimeter is defined by a collector drain.

13. A recreational surface as defined in claim 11 further including a nailer strip installed on the base restrainingly adjacent said layer of shock absorbing material, and an impervious sheet underlying the shock absorbing layer and secured to said nailer strip.

14. A recreational area as defined in claim 11 wherein the synthetic turf is filled.

15. A resilient recreational area having a perimeter and comprising:

a surface;

a layer of structurally bound resilient material placed over the foundation surface and having a thickness adequate to provide a predetermined degree of injury protection;

a layer of synthetic turf placed over the resilient material layer; and

a drain structure located adjacent at least a portion of the perimeter.

16. A resilient recreational area as defined in claim 15 further including an impervious drain blanket placed over the foundation but under the resilient material layer and partially overlying the drain structure.