The present invention relates to a tactile marker.

BACKGROUND OF THE INVENTION

Tactile markers may be positioned on walkway surfaces so as to assist pedestrians in identifying transitions, for example at pedestrian lights, at the foot or head of an escalator or stairway, and along the edge of a railway platform.

Tactile markers are commonly formed from metal or plastics materials. A tactile surface of such markers, being a surface that pedestrians interact with for example by walking on, will therefore often have a relatively smooth surface. It is however desirable to provide a tactile surface that is not overly smooth so as to reduce the occurrence of pedestrian slippage as they walk on the tactile marker. Some tactile markers are formed from metal and a non-slip sticker is then applied to the tactile surface. Applying the sticker is labour intensive and relatively expensive and the bonding of the sticker to the marker is often unsatisfactory.

Stems of tactile markers are secured in holes that are drilled into a walkway, which may for example be composed of asphalt. However, water penetrating into the holes often damages the asphalt . SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention there is provided a tactile marker comprising:

a head portion arranged to sit on a walkway surface; the head portion having a tactile surface and comprising a first material that has a recess at the tactile surface, the head portion further comprising a second material disposed in the recess and the second material comprising a frictional component forming at least a portion of the tactile surface; and

a depending stem arranged to be located as a press fit within a hole in the walkway, the depending stem comprising at least one barb having a generally annular land and a generally conical portion and further

comprising at least one sealing ring arranged to seal the hole in the walkway when the depending stem is located therein.

The sealing ring typically is| an annular projection having substantially parallel upper and lower lands. The sealing ring and the dependent step typically are integrally formed .

The barb typically is one of a plurality of barbs, such as 3 - 6 barbs .

One barb typically is positioned between the sealing ring and the head portion. The sealing ring may also be

positioned directly between the head portion and the barbs. In another example more than one of the barbs are positioned between the sealing ring and the head portion. Embodiments of the present invention have significant practical advantages. The sealing ring (and also the barbs) may have a diameter that slightly exceeds a

diameter of a hole in the walkway, which may for example be composed of asphalt. The sealing ring typically is shaped such that the sealing ring bends slightly upwards when the sealing ring is positioned into the hole in the walkway. The barbs have conical portions and typically are more solid than the sealing ring. Consequently, the barbs may predominantly shave along a wall of the hole when the stem is inserted into the hole and typically bend less than the sealing ring or do not bend at all. Especially the upwardly bent sealing ring contributes to sealing the hole and reduces likelihood that damaging water penetrates into the hole.

Further, the tactile marker typically is convenient to manufacture, for example using a moulding process, and provides a tactile surface that may reduce slippage. In addition, the recess typically allows a relatively strong bond to be formed between the frictional component and the head portion, which makes the frictional component less prone to being removed from wear. In one embodiment, the stem and head portions comprise the first material and are formed by injection moulding. The second material typically comprises a bonding component that couples the frictional component to the head portion. The bonding component of the second material may be disposed such that the bonding component is between the frictional component and the head portion. Alternatively, the frictional component may be dispersed within the bonding component wherein and a portion of the frictional component is exposed at the tactile surface. The

frictional component may cover the entire tactile surface.

In another embodiment, the second material is the

frictional component.

The first material may comprise a polymeric material such as a thermosetting polymeric material that is suitable for injection moulding. Especially in embodiments in which the bonding component couples the frictional component to the head portion, the bonding component may comprise an adhesive. The adhesive may be any suitable polymeric material such as polyurethane . In specific examples, the adhesive may be a two-part polyurethane adhesive.

The frictional component may comprise a granular material and at least some of the grains may be exposed at the tactile surface. The size of the granular material may be any appropriate size. For example, the granular material may have a grain size in the range of 1mm to 0.01mm, 0.5mm to 0.025mm or 0.1mm to 0.05mm. In specific embodiments, the frictional component comprises silicon carbide, but may alternatively comprise any other suitable component. The recess may comprise at least one recession below a surface of the recess and/or a projection. The at least one recession and/or projection may have a substantially dovetailed cross sectional shape. The at least one recession typically provides the

significant advantage of providing a stronger bond between the second material and the head portion. Consequently, the frictional component is more firmly held at the tactile surface.

It will be appreciated that the stem and the head portion may also be formed from other materials, such as a

metallic material.

In accordance with a second aspect of the present

invention there is provided a method of manufacturing a tactile marker comprising:

forming a head portion and a depending stem, the head portion being arranged to sit on a walkway surface, the depending stem being arranged to be located as a press fit within a hole in the walkway, the head portion having a tactile surface, the head portion and head portions comprising a first material and having a recess in the head portion at the tactile surface; and

disposing a second material into the recess, the second material comprising a frictional component forming at least a portion of the tactile surface.

In one embodiment the stem and the head portion are formed by injection moulded. The step of forming the head portion typically comprises forming at least one recession below a surface of the recess and/or a projection in the recess. The at least one recession may be formed so as to have a substantially dovetailed cross sectional shape.

Disposing the second material in the recess may comprise disposing a liquid second material into the head portion, coupling the frictional component to the head portion via the liquid second material, and hardening the liquid second material. Disposing the second material in the recess may also comprise dispersing the frictional

component in a liquid second material, and hardening the liquid second material with the dispersed frictional component in the recess of the head portion.

For example, disposing the second material in the recess may comprise poring a liquid second material into the recess and into at least one recession below the recess. The first material may comprise a polymeric material such as a thermosetting polymeric material that is suitable for injection moulding. In specific embodiments, the first material comprises polyurethane , but may alternatively comprise any other polymeric material that is suitable for injection moulding.

Coupling the frictional component to the head portion may comprise adhering the frictional component to the head portion via the bonding component . The bonding component may be an adhesive. The adhesive may be any suitable polymeric material such as polyurethane. In specific examples, the adhesive may be a two-part polyurethane adhesive . The frictional component may comprise a granular material. The granular material may have any appropriate grain size so as to achieve a frictional resistance of the tactile surface. For example, the granular material may have a grain size in the range of 1mm to 0.01mm, 0.5mm to 0.025mm or 0.1mm to 0.05mm. In specific embodiments, the

frictional component comprises any one of silicon carbide, but may alternatively comprise any other suitable

component . It will be appreciated that alternatively the stem and the head portion comprising the first material may be formed from other materials, such as a metallic material. The present invention provides in a third aspect a tactile marker comprising:

a head portion arranged to sit on a walkway surface and having a tactile surface, the head portion comprising a first material and having a recess in the first material at the tactile surface, the head portion further

comprising a second material disposed in the recess and the second material comprising a frictional component forming at least a portion of the tactile surface; and

a depending stem arranged to be located as a press fit within a hole in the walkway, the depending stem comprising barbs, each barb having a generally annular land and a generally conical portion.

The present invention provides in a fourth aspect a tactile marker comprising:

a head portion arranged to sit on a walkway surface ,- and

a depending stem arranged to be located as a press fit within a hole in the walkway, the depending stem comprising at least one barb having a generally annular land and a generally conical portion, the depending stem further comprising at least one sealing ring integrally formed with other portions of the depending stems and arranged to seal the hole in the walkway when the

depending stem is located therein.

The invention will be more fully understood from the following description of specific embodiments of the invention. The description is provided with reference to the accompanying drawings .

Brief Description of the Drawings

Figure 1 shows a perspective view of a tactile marker in accordance with an embodiment of the present invention;

Figure 2 shows a side view of the tactile marker of Figure 1;

Figure 3 shows a front elevation view of a head portion of a tactile marker in accordance with a further embodiment of the present invention and illustrating a recess of the head portion;

Figure 4 shows a perspective view of the tactile marker of Figure 1 having a second material disposed in the recess;

Figure 5 shows a perspective view of the tactile marker of Figure 1 having a second material comprising a frictional component disposed in the recess; and

Figure 6 shows a flow chart outlining a method of forming the tactile marker of Figure 5.

Detailed Description of Specific Embodiments

Embodiments of the present invention generally relate to a tactile marker comprising a head portion and a depending stem for positioning in a hole drilled into a walkway, such as a walkway composed of asphalt.

The tactile marker has a head portion that has a tactile surface. The stem and head portions comprise a first material and the head portion has a recess at a tactile surface. The head portion further comprises a second material that is disposed in the recess and the second material comprises a frictional component that forms at least a portion of the tactile surface. The tactile marker also comprises a sealing ring at the stem and that is arranged to seal the hole in the walkway.

Referring initially to Figures 1 and 2 there is shown the tactile marker 10 comprising a generally frusto-conical head portion 12 having a beveled surround 14 that extends to a marginal rim 16 and an integrally moulded stem 18 projecting downwardly from an underside of the head portion 12. The head portion 12 comprises a recess 20 which is filled with the second material that comprises a frictional component (the second material will be

described later with reference to Figures 4 and 5) .

In one embodiment, the head portion 12 and the stem 18 are formed from a suitable thermosetting polymeric material such as polyurethane . It will be appreciated however that the head portion 12 and the stem 18 may be formed from any appropriate material. In use, the head portion 12 is arranged to sit on the walkway surface such that the underside of the head portion 12 is substantially flush with the walkway surface and with the depending stem 18 located as a press fit within the drilled hole in the walkway. In this embodiment the stem 18 is formed along its length with five axially spaced barbs 22, the lowermost one of which comprises a generally conical end portion of the stem 18. The tactile marker also comprises a sealing ring 19 that is integrally formed with the stem 18. The sealing ring 19 comprises parallel upper and lower lands 21 and 23, respectively. The sealing ring 19 is annular and the diameter of a hole in which the stem 18 in use is

positioned typically is chosen to be slightly smaller than the diameter of the sealing ring 19. Consequently, the sealing ring 19 slightly bends upwards when the stem 18 is positioned into the hole in the walkway and thereby seals the hole.

In this embodiment the sealing ring 19 is positioned below two barbs 22 and above three barbs 22. It is to be

appreciated that in a variation of this embodiment the sealing ring 19 may not necessarily be positioned at a different height level of the stem 18. For example, one or three of the barbs 22 may be positioned above the sealing ring 19 and between the sealing ring 19 and the head portion 12.

Each of the barbs 22 comprises a generally annular land 34 having an outer periphery margin 36 and, formed integrally with the land 34, a generally conical portion 38. The conical portion 38 associated with each of the lands 34 is, as shown, located below the land 34 and has a major diameter that is the same as (or approximately equal to) that of the land 34, and the conical portion 38 has a cross-section that reduces in diameter in a direction away from the head portion 12.

Figure 3 shows a cross sectional view of the head portion 12 revealing the recess 20 having a plurality of dovetail shaped recessions 42. The recessions 42 may have any appropriate shape and orientation and typically are shaped to facilitate bonding a material, such as a polymeric material to the head portion 12. Figure 4 shows a variation of the tactile marker 40, which in this example does not comprise the sealing ring 19. An adhesive 44 has been pored into the recess 20 and the recessions 42. The liquid adhesive is arranged to harden and then provides a relatively strong bond. The bonding strength is facilitated by the anchoring function of the recessions 42. In this example the adhesive is a two-part polyurethane adhesive. However it will be appreciated that the adhesive may be any suitable adhesive. Figure 5 shows the tactile marker 40 after the frictional component 46 has been applied to the adhesive 44 so as to form at least a part of a tactile surface 48. The

frictional component 46 is in this example a granular material . The granular material may have any appropriate grain size so as to achieve a frictional resistance of the tactile surf ce. For example, the granular material may have a grain size in the range of 1mm to 0.01mm, 0.5mm to 0.025mm or 0.1mm to 0.05mm. In this specific example, the frictional component 46 comprises silicon carbide having a grain size in the range of 0.5mm to 0.025mm. Grains of the frictional component 46 are exposed at the tactile surface 48. In one embodiment the adhesive 44 is disposed between the frictional

component 46 and the head portion 12 such that the

adhesive 44 is substantially covered by the frictional component 46. Alternatively, the frictional component 46 may be arranged at the tactile surface 48 such that a substantial amount of the adhesive 44 is present at the tactile surface 48. In a further alternative, the

frictional component 46 is dispersed in the adhesive 44 wherein at least a portion of the frictional component is exposed at the tactile surface 48.

In light of the above, the tactile markers 10 and 40 therefore are convenient to manufacture and provide a tactile surface for substantially reducing slippage when the marker is in use walked on by pedestrians.

The dimensions of the various parts of the tactile marker 10 will be determined by particular application to which the marker might be put. However, in one embodiment of the marker the barbs 22 and the sealing ring 19 may have an outside diameter of 9.5 mm and the depending stem 18 will in use be pressed or otherwise forced into a drilled hole having a diameter within the range 8.0 to 8.5 mm. With such an interference fit, when, in use, the depending stem 18 is pressed into the hole will cause a tensile stress to be induced and the stem 18 will be held captive against longitudinal displacement from the hole by the barbs 22 and the sealing ring 19. Further, the stem 18 will be held captive against rotation within the hole by the splines 32 and the sealing ring 19 will seal the hole, which reduces likelihood that water penetrates into the hole. The splined region of the stem has the same effective diameter as the barbs 22 and the sealing ring 19 and, thus, also engages with an interference fit in the hole.

Further, in order to enhance retention of the stem 18 in the hole, an adhesive may in some circumstances be

inserted into the hole before the stem is inserted. Then, in order that the adhesive, when used, might flow along the full length of the stem and provide for maximum anchorage, the land 34 of each of the barbs 22 is formed with two diametrically disposed flat chordal regions 40, and the chordal regions 40 are displaced by substantially 90° on successive adjacent barbs 22.

Referring now to Figure 6 there is illustrated a method 50 of manufacturing a tactile marker, such as the tactile marker 10 or 40.

The method comprises moulding the head portion and

depending stem from first material (step 52) . This step typically comprises injection moulding. The stem and head portion of the tactile marker 10 or 40 are integrally from the same material, such as polyurethane , which can assist in convenient manufacturing.

The step of disposing 54 the second material in the recess may further comprise coupling the frictional component to the head portion using a bonding component.

The step of disposing 54 may be done as part of a

production line so as to further assist in the convenient manufacture of a tactile marker in accordance with the present embodiments .

Coupling the frictional component to the head portion comprises in this example disposing the bonding component such that the bonding component is between the frictional material and the head portion. In an alternative

embodiment, coupling the frictional component to the head portion may comprise dispersing the frictional material within the bonding component such that at least a portion of the frictional material is exposed at the tactile surface . When the bonding component is an adhesive, coupling the frictional component to the head portion comprises adhering the frictional component to the head portion.

Adhering the frictional component to the head portion using the bonding component may comprise disposing the bonding component in the recess in a liquid form and disposing the frictional component onto the bonding component prior to the bonding component hardening . In one embodiment, forming the head portion comprises forming at least one recession and/or projection in the recess wherein the at least one recession and/or

projection in the recess is formed so as to have a

substantially dovetailed cross sectional shape.

Although the invention has been described with reference to particular examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. For example, in the embodiment described in the Figures, the recess has a circular shape when viewed from the top. However, the recess may have any desired shape such as an annular shape. Further, although the stem and head portion are described as being formed by injection moulding, it will be appreciated that the stem and head portion may be formed from a metallic material, or any other suitable material.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.