GB2082233A - Road stud - Google Patents

Abstract

A cast iron road stud has a solid body 10 of which the undersurface 16 lies flush with the road surface. A depending root or boss 26 is anchored in a hole drilled in the road surface. A dovetailed reflective insert 18 fits in an undercut recess 14, being inserted from underneath the stud in the direction of arrow A. <IMAGE>

Description

SPECIFICATION Road stud This invention relates to studs of the type which are set into the surface of a road to give an indication to motorists of the edge of the road, or to mark a centre line or provide lane or other markings on the road surface.

Such road studs are commonly cast from metal, and one problem is then to secure thereto a reflective insert, e.g. one moulded from rubber or plastic and provided with reflective glass or plastic beads. It is known to secure these inserts in a recess in the body of the stud, e.g. using adhesive, and pushing the insert into the recess from the front. It is also known for the recess to be slightly undercut and the insert somewhat resilient so that it can be pushed in from the front and retained behind the undercut edges, thereby improving the security above that which can be provided by adhesive alone. However, in either case the insert must be permanently secured, so if the insert is damaged it is difficult to re-use the expensive cast body of the stud.

One aspect of this invention provides a road stud comprising a body having an undersurface for attachment to the road, and a recess in an exposed upper or lateral surface for receiving a mating reflective insert, wherein the recess extends through the body to the undersurface and is undercut so that the mating insert can pass into the recess from the underside. The insert can then be made so it will not pass out of the exposed side of the recess, so it does not require securing with adhesive.

Another problem with such road studs is to ensure that they do not become dislodged in time.

With existing studs, sometimes the mere weight of heavy traffic continually pounding over them causes the studs to become insecure. In other cases, water can enter beneath the underside of the stud on the road surface and in frosty weather this can lift the stud.

Another aspect of this invention provides a road stud comprising a body with an undersurface for attachment to the road, and having one or more downwardly opening hollowed-out recesses.

Two road studs according to the invention will now be described by way of example with reference to the accompanying drawings, wherein: Fig. 1 is a partly sectional side view of the first stud, together with a reflective insert, Fig. 2 is a view on the line Il-Il in Fig. 1, without the reflective insert, Fig. 3 is a front elevation of the insert, in the direction of arrow Ill in Fig. 1, Fig. 4 is a section on the line lV-IV in Fig. 1, and Fig. 5 is a view corresponding to Fig. 2, but showing the second stud.

Referring to Figs. 1 to 4, the first stud is of cast iron and is generally mushroom-shaped. It has a solid body 10 which is oval in plan and has sloping sides 11 giving a domed upper surface. The very top 12 of the dome is flattened and its shape gives the stud a low profile when in use so that it presents as little obstruction as possible to vehicle wheels. The undersurface 16 of the body 10 will in use lie flush with the road surface.

The body 10 includes a recess 14 at one end of the oval, extending from the exposed, upwardly and laterally facing side surface 11 to the undersurface 1 6 of the body 1 0. This recess forms an opening in the bottom peripheral edge of the body 10 between the sloping side 11 and the undersurface 1 6. The opening of the recess 14 into the undersurface 16 is larger than that into the side 11, and is trapezoidal, the largest side of the trapezium being away from the edge of the body 10 (see Fig. 2). This gives the recess 1 4 a dovetailed shape, and from the point of view of the opening into the exposed side 11 the recess is undercut both in a horizontal plane (as best seen in Fig. 2) and in a vertical plane (Fig. 1).

Fig. 3 shows an insert which has a complementary shape for fitting in the recess 14.

The body 1 8 of the insert is of rubber, plastics material, or the like, and is moulded around two clear or coloured glass beads 20. As shown in Fig. 1, the beads 20 project slightly from the front face 22 of the insert, so that in use they are cleaned by the tyres of passing vehicles. The rear faces 24 of the beads 20, and possibly the side faces, are given a silvered coating, so that the beads reflect the light of vehicle headlamps. More or less beads 20 could be provided if desired, and they could be made of transparent plastics material.

The insert 1 8 is inserted into the recess 14 from the underside, in the direction of arrow A in Fig. 1. Although the insert 18 is somewhat resilient, because of the undercut shape of the recess and the dovetail shape of the insert, it cannot pass out of the recess through the exposed side 11 of the stud. Once the undersurface 1 6 of the body 10 is installed flush with a road surface, therefore, the insert is held captive, and no permanent securing with adhesive or the like is necessary. This means that if the stud is ever removed from the road, the insert can be replaced as necessary and the stud re-used. Furthermore, it is not necessary for the beads 20 to be removable from the insert in case of damage (because the entire insert can be replaced) and so the insert can be manufactured more cheaply than at present.

From the undersurface 16, there is a depending boss or root 26. This is slightly offset from the centre of the body, to allow for the recess 14.

Although the upper portion 26a of the boss or root 26 is solid and of circular cross-section, this merges into the lower portion 26b which is hexagonal and has an internal bore 28 (see Fig. 4) which is open at the lower end 30 of the boss or root 26. Furthermore, between the portions 26a and 26b there is a waisted portion 26c or lesser diameter. In the underside 1 6 of the body 1 0, surrounding the central boss 18, there is an annular, hollowed-out recess 30.

In use, with the stud upside down, the hollow central bore 28 is filled with hot bitumen. A hole is then bored in the tarmac of the road surface to accept the boss 26. When the bitumen has started to harden so that it does not run out of the bore 28, more bitumen is placed in the hole bored in the road surface and the stud is placed in position with the boss 26 in the hole. This of course causes the bitumen in the hole to overflow, and it is forced into the recess 30, which leads it to flow out under the peripheral edge region 32 of the undersurface 1 6 to form a seal between that region and the road surface. Any excess bitumen is then removed, and the bitumen is allowed to harden to secure the stud in place.

The bitumen in the hole in the road surface will when solidified be integral with the bitumen in the central bore 28, and the fact that this bitumen is solid within the bore 28 and the recess 30 and around the waisted portion 26c serves under normal conditions to key the road stud securely to - the road surface. The non-circular portion 26b prevents rotation. In very hot weather, of course, the bitumen will soften, and in this case the road stud is prevented from being dislodged because if it were a vacuum would tend to form within the bore 28 and the recess 30. Moreover, because the recess 30 causes a seal to be formed around the peripheral edge region 32, it is not possible for moisture to enter underneath the stud so that the stud does not tend to be lifted by frost.

It will be appreciated that a further benefit of the bore 28 and recess 32 is in reducing the amount of metal required for the casting. The stud is thus lighter and cheaper.

Other metals such as cast aluminium could be used in place of cast iron, or the stud could be made from a hard plastics or mastic material if desired.

The embodiment described above, having only one recess 14 to receive a reflective insert, is particularly suitable for verge or hard shoulder markers on motorways and dual carriageways.

Fig. 5 shows the underside of a stud which is somewhat squarer in plan view and has two recesses 14, at opposite sides of the stud. The form of these recesses is exactly as described above, so that the insert of Fig. 3 will fit either stud. In place of the hollowed-out recesses 30, the underside 16 of the stud in Fig. 5 has a number of crescent-shaped recesses 34, 36. (Although two types 34, 36 of such recesses are shown, in practice only one or the other type will be provided, on both sides of the central boss 26.) These recesses 34, 36 serve the same function as the recess 30 in Figs. 1 and 2. The other features of the stud of Fig. 5 are similar to those described above, and so will not be described further.

The stud of Fig. 5 is useful for more minor roads, where bi-directional reflective indication is required.

Claims (20)

1. A road stud comprising a body having an undersurface for attachment to the road, and a recess in an exposed upper or lateral surface for receiving a mating reflective insert, wherein the recess extends through the body to the undersurface and is undercut so that the mating insert can pass into the recess from the underside'

2. A road stud according to claim 1 wherein the recess is in a sloping, upwardly facing lateral surface.

3. A road stud according to claim 1 or claim 2 wherein the recess is undercut both when viewed in vertical section and when viewed in horizontal section.

4. A road stud according to any one of the preceding claims having two said recesses, facing in different lateral directions.

5. A road stud according to any one of the preceding claims together with a reflective insert of complementary shape to the recess, the insert being inserted in the recess.

6. A road stud according to claim 5 wherein the insert comprises one or more reflective beads in a moulded surround.

7. A road stud according to any one of the preceding claims having a boss or root depending from the undersurface.

8. A road stud according to claim 7 wherein at least part of the boss or root is of non-circular cross-section.

9. A road stud according to claim 7 or claim 8 wherein the boss or root has a waisted shape.

10. A road stud according to claims 7, 8 or 9 wherein the boss or root is hollowed out, opening at the bottom.

11. A road stud according to any one of the preceding claims wherein the undersurface of the body has one or more further recesses hollowed out of the body.

12. A road stud substantially as described herein with reference to the accompanying drawings.

13. A reflective insert for a road stud according to any one of the preceding claims, comprising a body with a reflective surface, the body being formed so as to fit in a said undercut recess of the stud with the reflective surface facing outwardly and so as not to be removable from the recess in the outward direction.

14. An insert according to claim 13 wherein the reflective surface is provided by one or more reflective beads in the surface of the insert body.

1 5. An insert according to claim 14 wherein the body is moulded around the beads from rubber or plastics.

1 6. A road stud comprising a body with an undersurface for attachment to the road, and having one or more downwardly opening hollowed-out recesses.

17. A road stud according to claim 16 having a' boss or root depending downwardly from the undersurface, the boss or root being hollowed out' and open at the bottom to provide a said recess.

1 8. A road stud according to claim 1 7 wherein the boss or root is of non-circular cross-section.

19. A road stud according to claim 17 or claim 1 8 wherein the boss or root has a waisted shape.

20. A road stud according to any one of claims 16 to 19 wherein the undersurface of the body has one or more said recesses.