BACKGROUND OF THE INVENTION
The present invention relates to municipal/construction castings and more particularly to detectable warning plates.
Detectable warning plates are widely used as a tactile warning for the blind in sidewalks, walkways and other similar structures. Typically, detectable warning plates are embedded in the sidewalk and have an upper surface with an arrangement of regularly-spaced protrusions in the shape of truncated domes. The size, shape and arrangements of protrusions are specified in the ADA Accessibility Guidelines for Detectable Warnings. These specifications are intended to provide uniform warnings that can be readily detected by the blind. In some applications, the prescribed pattern of protrusions is formed directly in the concrete. Unfortunately, it can be difficult to manufacture protrusions in concrete that are uniform and of consistently high quality. Further concrete protrusions are highly susceptible to wear and other damage.
Accordingly, a variety of detectable warning products have been developed to be embedded in concrete and provide the prescribed pattern of protrusions. Detectable warning plates are manufactured from materials ranging from plastic to iron. Experience has revealed that detectable warning products manufactured from plastics, composites and other relatively light materials are more susceptible to wear and more prone to damage from snow plows and other maintenance equipment. Further, conventional detectable warning products of essentially all types can be susceptible to separation from the concrete in which they are embedded. For example, external forces, such as a snow plow, may break the detectable warning plate away from the concrete. Further, the expansion and contraction associated with temperature changes can also cause a detectable warning plate to separate from the concrete. Conventional detectable warning plates have been provided with interlocking structures on their undersurface. It can, however, be difficult to get the concrete to adequately flow around the interlocking structure and these conventional efforts have met with only limited success.
Accordingly, there remains a long felt and unmet need for a detectable warning product that is durable, easily installed, remains embedded and does not warp during installation or use.
SUMMARY OF THE INVENTION
The aforementioned problems are overcome by the present invention wherein a detectable warning plate is provided with integral locking lugs. In one embodiment, the plate includes two lugs arranged in a regular pattern on the bottom of the plate. In this embodiment, each lug may extend downwardly from the undersurface of the plate and may be somewhat C-shaped. The lugs are spaced a sufficient distance from the undersurface of the plate to readily permit the flow of concrete around the lug. The plate may be cast from iron and may include lugs that are formed integral with the plate during casting.
In one embodiment, the plate may define a vent hole extending vertically through the plate above each lug. The vent holes permit air to escape from beneath the plate during installation as concrete flows in around the lugs.
In another embodiment, the plate includes support ribs to strengthen the plate and, among other things, reduce the possibility of warping or other deformation during manufacture. In one embodiment, the support ribs extend from the undersurface of the plate and extend around the plate near its periphery. In another embodiment, the support ribs are arranged in an X-shaped configuration with its intersection located at the approximate center of the plate. In these embodiments, the lugs may be extensions of the support rib.
If desired, the upper surface of the detectable warning plate may be textured to improve traction. The design and configuration of the texture may vary from application to application. For example, this texture may extend over all or a portion of each truncated dome-like protrusion, and/or over the surfaces between the protrusions.
The present invention provides a detectable warning plate that is durable and easy to install. The lugs provide an integral structure that can be embedded within concrete to provide a durable and lasting attachment. The broad spacing of the lugs permits wet concrete to easily flow around the lugs to interlock the plate and the concrete. The vent holes facilitate installation by permitting air trapped within the lugs to escape as the wet concrete flows around the lugs. Otherwise, air pockets trapped under the plate might have a significant adverse impact on the interlock between the plate and the concrete. The integral support ribs dramatically reduce the risk of warping during manufacture and may provide additional structure for the lugs.
These and other objects, advantages, and features of the invention will be readily understood and appreciated by reference to the detailed description of the current embodiment and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top perspective view of a detectable warning plate according to an embodiment of the invention.
FIG. 2 is a bottom perspective view of the detectable warning plate.
FIG. 3 is a perspective view showing the detectable warning plate embedded in a sidewalk.
FIG. 4 is a right side elevational view of the detectable warning plate.
FIG. 5 is an enlarged perspective view of a portion of the detectable warning plate showing a single protrusion.
FIG. 6 is a bottom plan view of the detectable warning plate.
FIG. 7 is a sectional view showing the detectable warning plate shortly after being embedded in wet concrete.
FIG. 8 is a sectional view similar to FIG. 7 showing the detectable warning plate after the wet concrete has filled in around the lugs.
FIG. 9 is a perspective view of a first alternative detectable warning plate.
FIG. 10 is a top plan view of the first alternative detectable warning plate.
FIG. 11 is a bottom plan view of the first alternative detectable warning plate.
FIG. 12 is a sectional view of the first alternative detectable warning plate taken along line 12-12 of FIG. 10.
FIG. 13 is a top view showing a plurality of the first alternative detectable warning plates installed at a curb.
FIG. 14 is a bottom perspective view of a second alternative detectable warning plate.
FIG. 15 is a bottom perspective view of a third alternative detectable warning plate.
DESCRIPTION OF THE CURRENT EMBODIMENT
A detectable warning plate in accordance with an embodiment of the present invention is shown in FIGS. 1 and 2, and is generally designated 10. The detectable warning plate 10 generally includes a main body 12 and a plurality of lugs 14a-d that extend from the undersurface of the plate 10. As perhaps best shown in FIG. 3, the detectable warning plate 10 may be installed in sidewalks S, walkways and other similar structures to signal the end of the sidewalk to the blind. During installation, the lugs 14a-d are embedded in wet concrete to lock the plate 10 in place within the concrete. If desired, a plurality of detectable warning plates 10 may be installed adjacent to each other to provide a warning area of the desired size.
Referring now to FIGS. 1, 2 and 4, the detectable warning plate 10 generally includes a main body 12 and a plurality of lugs 14a-d. In the illustrated embodiment, the main body 12 is a generally rectangular plate. However, its shape may vary from application to application as desired. For example, the main body 12 may be round, oval, square or irregular in shape. The dimensions of the plate 10 may also vary from application to application depending largely on the structural requirements and the environment in which the plate 10 is to be installed. The main body 12 generally includes an upper surface 16 and a lower surface 18. In the illustrated embodiment, an arrangement of protrusions 30 extend upwardly from the upper surface 16 of the main body 12 in compliance with applicable ADA Accessibility Guidelines for Detectable Warnings. FIG. 5 is an enlarged view of a portion of the plate 10 showing a single protrusion 30. As shown, each protrusion 30 is shaped as a truncated spherical dome having a planar top surface 32. The upper surface 16 of the plate 10 may alternatively include protrusions of other sizes, shapes and arrangements. The upper surface 16 may optionally be textured to provide improved traction. Given the practical difficulties of showing the texture in all Figs., the texture is shown only in FIG. 5. In the illustrated embodiment, the planar portions of the upper surface 16 of the plate 10 and the planar top surface 32 of each protrusion 30 may be textured (See FIG. 5). As shown in FIG. 5, the curved surfaces of protrusions 30 in the illustrated embodiment are not textured. The plate 10 may include essentially any pattern of texturing, but in the illustrated embodiment, the texturing includes a plurality of regularly spaced diamond-shaped elements 31.
The plate 10 may optionally include support ribs. In the illustrated embodiment, support ribs 20a-b extend from the lower surface 18 of the main body 12 (See FIGS. 2 and 6). The support ribs 20a-b of this embodiment are arranged in a generally X-shaped configuration. As shown, the support ribs 20a-b may extend along imaginary lines interconnecting opposite comers of the rectangular shaped main body 12. In this embodiment, the two support ribs 20a-b intersect at the approximate center of the main body 12. The precise size of the support ribs 20a-b may vary from application to application depending in large part on the specific characteristics of the main body 12. For example, the depth and width of the support ribs 20a-b will typically be selected to provide sufficient strength to prevent warping of the plate 10 during manufacture. The number, size, shape and configuration of the support ribs may vary from application to application, as desired.
As noted above, the plate 10 includes lugs 14a-d that extend from the undersurface of the main body 12. The lugs 14a-d may be integrally formed with the plate 10 or may be separately manufactured and attached to the plate 10. In the illustrated embodiment, the plate 10 includes four lugs 14a-d extending from and in alignment with the support ribs 20a-b. The lugs 14a-d may alternatively be separate from the support ribs 20a-b. As shown, the lugs 14a-d of this embodiment are generally C-shaped, each having an interlock section 34 and opposite end sections 36 and 38. The end sections 36 and 38 are joined to the lower surface 18 of the main body 12. The interlock section 34 of each lug 14a-d is spaced a sufficient distance away from the main body 12 to allow the free flow of concrete around the lugs 14a-d during installation in wet concrete. In the illustrated embodiment, each lug is spaced approximately 33 mm from the lower surface 18. The number, size, shape, arrangement and configuration of the lugs may vary from application to application depending in large part on the characteristics of the main body 12, the characteristics of the concrete (or other foundation in which the plate 10 is to be embedded) and the desired strength of the bond between the plate 10 and the foundation.
The main body 12 may define a plurality of vent holes 40a-d that permit air to vent from beneath the plate 10 during installation as concrete flows around the lugs 14a-d. In the illustrated embodiment, a single vent hole 40a-d is defined vertically through the main body 12 in alignment with the approximate center of each lug 14a-d. As a result, the illustrated embodiment includes four vent holes 40a-d. The number, size, shape and location of the vent holes 40a-d may vary from application to application as desired. For example, two or more vent holes may be defined at each lug. By increasing the number of vent holes, the size of each vent hole may be decreased.
The detectable warning plate 10 may be installed in wet concrete using conventional techniques and apparatus. For example, the plate 10 may be placed in wet concrete as the sidewalk or other infrastructure is being formed. The plate 10 is placed in the concrete after the concrete has been poured and before the concrete has cured to the point where it has lost the ability to flow. The plate 10 will typically be installed so that the planar upper surface 16 of the plate 10 is aligned with the top surface of the surrounding concrete. The plate 10 is positioned with the lugs 14a-d pushed down into the wet concrete. When placed in wet concrete, the inherent flowing nature of the wet concrete will cause the concrete to flow around the lugs 14a-d (See FIG. 7). As the concrete flows around the lugs, air trapped under the plate 10 is free to vent from beneath the plate 10 through the vent holes 40a-d. In this way, the vent holes 40a-d prevent air from being trapped beneath the plate 10, thereby permitting the concrete to completely entrapment of the lugs within the concrete (See FIG. 8).
The present invention may be manufactured using any of a variety of conventional manufacturing techniques. For example, the detectable warning plate 10 may be manufactured using conventional cast iron manufacturing techniques and apparatus. In the illustrated embodiment, the plate 10 is cast as a one-piece component having integral support ribs 20 and integral lugs 12a-d. Although plate 10 is manufactured from iron, it may alternatively be manufactured from other materials as appropriate for the specific application.
A detectable warning plate 110 in accordance with another embodiment of the present invention is shown in FIGS. 9-13. In this embodiment, the plate 110 includes a slight taper and a slight curve so that a plurality of plates may be positioned adjacent to one another to form a curved warning zone. For example, FIG. 13 shows four detectable warning plates 110 mounted adjacent to one another in an exemplary sidewalk application. The amount of taper or curve in each plate may vary from application to application as desired. However, in the illustrated embodiment, the wider curved edge 111 of the plate follows an 18⅞ inch radius of curvature and it takes 20 plates to complete a full 90 degree turn. As shown in FIGS. 9 and 11, the plate 110 includes a main body 112 having an upper surface 116 and a lower surface 18. A plurality of protrusions 130 extend from the upper surface 116 in a regular pattern. In this case, the protrusions 130 are truncated spherical domes as described above in connection with plate 10. A plurality of lugs 114a-b extend from the undersurface of the plate 110. In the embodiment of FIGS. 9-13, the plate 11—includes two lugs 114a and 114b located adjacent opposite longitudinal edges of the plate 110. The number, size, location and configuration of the lugs 114a-b may vary from application to application as desired. The plate 110 also includes a support rib with segments 120a-d that extend from the lower surface 18 of the plate 110 (See FIG. 12). In this embodiment, the support rib segments 120a-d extend around the plate 110 adjacent to the periphery of the plate 110. As perhaps best shown in FIG. 12, the lugs 114a-b are integral with the support rib segments 120a-d. The number, size, shape and configuration of the support rib and support rib segments 120a-d may vary from application to application. The plate 110 defines a plurality of vent holes 140a-b—one vent hole 140a or 140b in alignment with each lug 114a-b. The vent holes 140a-b are of sufficient size to permit air to escape from beneath the plate 110 as concrete flows into the space between the lower surface 118 and the lugs 114a-b. The plate 110 may also include one or more additional vent holes that permit air to vent from beneath the plate 110 during installation. For example, plate 110 includes a vent hole 141 that facilitates venting of air from within the boundary of the support rib segments 120a-d.
Detectable warning plates 210, 310 and 410 in accordance with three additional alternative embodiments of the present invention are shown in FIGS. 14, 15 and 16, respectively. These three alternative embodiments illustrated different plate shapes and lug configurations. FIG. 14 illustrates a generally square plate 210 having a peripheral support rib with segments 220a-d and two lugs 214a-b. The lugs 214a-b are integral with the support ribs segments 220a-d. The plate 210 defines a first pair of vent holes 240a-b in alignment with the lugs 214a-b and a second pair of vent holes 241a-b disposed inside the boundary of the support rib segments 220a-d. Although not shown, the upper surface of the plate 210 may include a plurality of protrusions, such as the truncated spherical domes described above. FIG. 15 illustrates a rectangular plate 310 having a peripheral support ribs with segments 320a-d and two lugs 314a-b. The lugs 314a-b are integral with the support rib segments 320a-d, and are disposed toward opposite ends of the plate 310. The plate 310 defines a first pair of vent holes 340a-b in alignment with the lugs 314a-b and a second pair of vent holes 341a-b disposed inside the boundary of the support rib segments 320a-d. Although not shown, the upper surface of the plate 310 may include a plurality of protrusions, such as the truncated spherical domes described above. Finally, FIG. 16 illustrates a rectangular plate 410 that is quite similar to plate 310. Plate 410 includes a peripheral support rib with segments 420a-d and two lugs 414a-b. The lugs 414a-b are integral with the support rib segments 420a-d, and are disposed toward opposite ends of the plate 410. The plate 410 defines a first pair of vent holes 440a-b in alignment with the lugs 414a-b and a second pair of vent holes 441a-b disposed inside the boundary of the support rib segments 420a-d. Although not shown, the upper surface of the plate 410 may include a plurality of protrusions, such as the truncated spherical domes described above. The embodiments of FIGS. 14-16 are illustrated to provide examples of alternative embodiments of the present invention, and not to provide limitations on the scope of the invention. Each of these embodiments may include any of the variations described above in connection with plate 10 and plate 110.
The above description is that of the current embodiment of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.
Patent Application
20070201949
