METHOD FOR PRODUCING DETECTABLE WARNINGS ON SURFACES

AND PRODUCTS THEREOF

FIELD OF THE INVENTION The present invention relates to the field of surface treatment, and more specifically to the creation of detectable warnings that protrude from a target surface.

BACKGROUND OF THE INVENTION

With increasing public awareness regarding persons with disabilities, many local and regional laws, regulations, and ordinances have been passed that require modifications to existing structures and consideration of the disabled when undertaking new construction. Perhaps the most significant new legislation has been the enactment of the Americans with Disabilities Act (ADA). This Act sets forth numerous requirements regarding access to and use of facilities by the disabled.

One of the more widely recognized disabilities is impaired vision. While previously the incorporation of tactile indicia and detectable warnings was discretionary, under the ADA, suitable tactile indicia and detectable warnings must be provided in many situations. Moreover, the types of acceptable detectable warnings are now regulated.

Specifically, the ADA now requires detectable warnings on the walking surface of curb ramps or on a walking surface prior to the surface or ramp crossing or adjoining a vehicular way not otherwise separated by curbs, railings, or other such elements.

Similarly, if there are no curbs, railings, or the like between a walking surface and perhaps, for example, a reflecting pool, detectable warnings must be used.

Detectable warnings have been defined as "a standardized integral surface feature built in or applied to walking surfaces or other elements to warn individuals with visual impairments of hazards on a circulation path." The technical specifications of the ADA require that detectable warnings on walking surfaces have a specific truncated dome pattern. This unique pattern is intended to provide a consistent and uniform surface that is distinctive from other materials and, therefore, recognizable as a warning to pedestrians that they are approaching a potentially dangerous area. The detectable warnings must contrast visually with adjoining surfaces, and material used to provide contrast must be an integral part of the walking surface. Though not required, a 70% contrast ratio is recommended.

When discussing detectable warnings for pedestrians, three traditional techniques of achieving such warnings have been used: surface forming, etching, and deposition. In surface forming, a desired pattern is created in the surface during its formation stage. For example, when a concrete walk is being formed, the detectable warning pattern is created therein usually by stamping the surface or by applying a prefabricated surface treatment. Etching, if done during the formation of the surface, provides a low cost method for treating a traveled surface to have the required detectable warning. However, if etching is desired on an existing surface, a material removal process must usually be used which often incorporates the use of abrasives or the like. With both of these means, however, there is little ability to incorporate visual contrast or other required or desirable aspects identified in the ADA.

Deposition techniques are usually carried out after the surface formation process has been completed. Thus, such techniques are suitable for both new and old work. A significant problem associated with many other deposition techniques is that the resulting detectable warnings may be abrupt so as to engender the tripping of a person using that surface. In addition, many surfaces having detectable warnings are slippery and/or lack contrast when compared to the base surface. Moreover, it is desirable to have detectable warnings that are uniform in appearance—a quality that some deposition techniques fail to provide. SUMMARY OF THE INVENTION

One embodiment of a method for producing detectable warnings on surfaces includes providing a mat with a top surface and a bottom surface. The mat has a pattern of truncated dome-shaped cavities with a dome upper surface and a dome lower surface. The mat also has at least one aperture, wherein the aperture passes from the dome upper surface to the top surface of the mat. The method further includes securing the bottom surface of the mat to a substrate surface. The method also includes preparing a viscous substance having the ability to cure into a solid, injecting the viscous substance into each aperture of the mat to fill the truncated dome-shaped cavity, permitting the viscous substance to substantially cure, and removing the mat to expose raised detectable warnings on the substrate surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to

the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a perspective view of detectable warnings formed on a target, substrate surface. FIGURE 2 is a cross-sectional view of a detectable warning formed on a target surface as shown in FIGURE 1.

FIGURE 3 is a bottom perspective view of a mat used to form the detectable warnings, wherein dome-shaped sections have been formed on the bottom surface of the mat. FIGURE 4 is a top perspective view of the mat depicted in FIGURE 3.

FIGURE 5 is a cross-section of the mat depicted in FIGURES 3 and 4, wherein the mat has been secured to a target surface such that a blended material may be injected into the dome-shaped cavities in the mat to form the detectable warnings depicted in FIGURE 1. FIGURE 6 is a cross-sectional view of the mat depicted in FIGURES 3 and 4 being removed from the target surface to reveal the detectable warnings depicted in FIGURE 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGURE 1, a substrate or target surface 14 having a pattern of detectable warnings in the form of truncated domes 16 formed thereon is shown. The truncated domes are illustrated as arranged in an "in-line" or "square" pattern as shown in

FIGURE 1. The rows of truncated domes may instead be rotated (for example at

45 degrees) in relation to the substrate surface 14 to produce an offset pattern.

Preferably, the truncated domes are spaced at least 1.6" from the center of one truncated dome to the center of the adjacent truncated dome, and no more than 2.4" apart for both the in-line pattern and the offset pattern. In addition, a multiple sinusoidal pattern in a stacked relationship, as shown in U.S. Patent No. 5,385,770, may instead be used to provide a greater likelihood that an object, in constant contact with surface 14, will encounter a truncated dome 16 in the least distance. For ease of illustration and clarity, only the in-line pattern is shown.

A cross section of a truncated dome 16 bonded to substrate 14 is shown in FIGURE 2. Inclined peripheral surfaces 20 may have curved upper and lower transitions 22 and 24 with upper surface 26 and substrate 14, respectively, so that an

object such as a cane, shoe, or foot, as well as an implement such as a shovel or squeegee, will not jam or lodge in the otherwise sharp corners or edges created at these interfaces. Beneficially, these curved transitions 22 and 24 increase the truncated dome's resistance to dislodgment from lateral impacts by permitting a certain degree of impact redirection. The truncated domes 16 are preferably at least .9" in diameter along the bottom of the truncated dome 16, and no more than 1.4" in diameter. Along the top of the truncated dome, the diameter is preferably at least .45" and no more than .6". The truncated domes 16 are preferably approximately .2" in height. However, other truncated dome shapes and sizes may also be used. For instance, as shown in U.S. Patent No. 5,385,770, additional designs may include an elongated elliptical design, a diamond shaped design, an asymmetrical elongated elliptical design, or a dumbbell design. Regardless of the form of truncated dome 16, each truncated dome is characterized as having an inclined peripheral surface and somewhat rounded or curved transitions between both the lower substrate 14 and the upper surface of the truncated dome 16. Referring to FIGURE 3, a mat 30 or similar element may be used to create the afore-described detectable warnings or truncated domes 16 on a substrate surface 14. The mat 30 may consist of either a rigid, flexible, or semi-flexible material, where the mat 30 may be preferably formed using a molding technique, such as injection molding. The mat mold may also be designed to produce dome-shaped cavities 34 in the mat 30 during the molding process. The mold may include an upper and lower portion, and each portion of the mat mold may contain a portion of a mold cavity. The mold may also include inwardly extending projections that generally conform to the shape of a truncated dome 16 to form the dome-shaped cavities 34 during the molding process.

During the molding process, the upper and lower portions of the mat mold are coupled together to define the mold cavity therebetween. At least one inlet channel may be included in the mold to allow the inflow of material through the inlet channel and into the mold cavity. An injection nozzle may inject material through the inlet channel and into the mold cavity. The injected material may fill the mold cavity to form the mat 30. After the material injected into the mold cavity has cured, the mold portions may be separated and the mat 30, with dome-shaped cavities 34, may be removed from the mold. Each dome-shaped cavity 34 formed during the molding process represents a mold for forming the desired truncated domes 16 on the substrate surface 14. Thus, the material of the mat 30 defining each dome-shaped cavity 34 is in roughly complimentary

relationship to the desired physical dimensions of the truncated dome 16. The dome- shaped cavities 34 may be formed during the molding process on the bottom surface of the mat 36, such that the bottom of the dome-shaped cavities 34 align the bottom surface of the mat 36. The dome-shaped cavities 34 may be arranged in a desired pattern to enhance the detectability of the target surface.

Referring to FIGURES 3 and 4, an aperture 40 may be formed in the top of each dome-shaped cavity 34, where the aperture 40 passes from the upper surface 28 of the dome-shaped cavity 34 to the upper surface of the mat 38. The apertures 40 may be formed during the molding process at the same time the dome-shaped cavities 34 are formed. The mat mold may include inwardly extending cylindrical projections that extend from the top of the dome-shaped projections. These inwardly extending cylindrical projections will form an aperture that passes from the upper surface 28 of the dome-shaped cavity 34 to the upper surface of the mat 38 when the mold cavity is injected with material. Referring to FIGURE 5, the truncated domes 16 may be formed by first placing the mat 30 on a substrate surface 14. The mat 30 may include a sealant or adhesive surface 42 that covers the bottom surface of the mat 30. Thus, the mat 30 may be placed on the substrate surface 14 such that the bottom surface of the mat 30 may adhere to the substrate surface 14 by means of the adhesive surface 42. After the mat 30 is placed upon the substrate surface 14, a material 32 may be injected into each aperture 40 to fill the dome-shaped cavities 34. The material 32 may be used to fill the dome-shaped cavities 34 by using a manually operated squirt bottle or other manually operated or powered device with a nozzle sufficiently small to inject the material 32 into the aperture 40. After the material 32 has completely, or at least substantially, cured in stasis, the mat 30 may be removed to reveal the truncated domes 16, as shown in FIGURE 6. Once the mat 30 has been removed, a final coat of viscous catalyzed material may be applied to the substrate surface 14 and the truncated domes 16 to smoothen any abnormalities or blemishes and help ensure an even appearance.

The truncated domes 16 of the present invention may be formed from material 32, which may comprise a methacrylate monomer blended with binders, pigments, and an abrasive. Ideally, the blended material has good abrasion resistance, chemical resistance, and longevity. In one form of the present invention, the composition of the detectable warnings may be a methacrylate monomer blend having glass fiber binders, pigments,

and reflective material. The use of a methacrylate monomer helps engender strong bond characteristics with normally encountered substrate surfaces such as asphalt, concrete, and wood. The use of glass fibers enhances structural properties of the detectable warnings and reduces the amount of resin mixture needed for any given application. The percentage pigment chosen provides adequate color contrast under the provisions of the ADA. The use of reflective material such as glass spheres or beads enhances low light detection of the detectable warnings and further decreases the amount of monomer needed. Finally, the percentage abrasive not only increases the potential coefficient of friction of the warnings, but also provides additional strength as an aggregate and decreases the overall amount of resin needed for a given application.

While a preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.