GB2212194A - Traffic cone with self erecting base flange - Google Patents

Abstract

A traffic cone comprises an upstanding member 2 and a flange 4. The flange 4 is made from an elastomeric material and is relatively thin. The parameters of the cone are selected so that tipping of the cone stresses the material of the flange so that a restoring force is generated to return the cone to the upright position. <IMAGE>

Description

HIGHWAY MARKERS This invention relates to highway markers.

Highway markers such as traffic cones and cylindrical posts are commonly used to control and delineate traffic flows. They are often used in positions where traffic passes very close to them, and consequently there is the danger that they will be knocked over, either by vehicle slipstreams or by the vehicles themselves. Once knocked over, of course, they no longer perform their intended function, but they also tend to roll about on the highway causing danger and inconvenience to drivers.

Proposals have been made for highway markers which have some self-righting capability. For example, GB2077332 discloses a marker having an upstanding member and a flexible flange which can right itself after being tilted away from the upright position.

When the marker is tilted, the part of the flange which remains in contact with the ground is flexed to provide a resilient force tending to return the marker to the upright position. At the same time, the part of the flange which is lifted from the ground flops in a direction away from the top of the marker to counterbalance the weight of the upstanding member.

However, this marker is not capable of righting itself if the marker is tipped so far that the upstanding member comes into contact with the ground.

Furthermore, it cannot be guaranteed that the uppermost part of the flange will flop in the correct direction; it may flop towards the upstanding member, in which case it will assist tipping of the marker.

US3705566 also discloses self-righting markers having upstanding members and flexible flanges, in which the problem caused by the upper part of the flange of the tipped marker is avoided. In one embodiment, the upstanding member is positioned towards one end of a rectangular flange so that there is a large area of flange projecting to one side of the upstanding member. If the marker is tipped towards this side, the short part of the flange on the opposite side hardly flexes at all, and so has a negligible effect on the position of the centre of gravity of the marker as a whole. Thus, the marker is moved upwards from the tilted position solely by the resilience of the flange. However, the disadvantage is that the marker is self-righting only if tipped in one direction; if tipped away from the extended part of the flange, or to either side, it will not right itself.

In alternative embodiments, the upstanding member is disposed centrally on the flange, but, as in GB2077332, self-righting is assisted by the upper region of the flange of the marker which, when the marker is tilted, flops away from the upstanding member. The flange is specially formed in order to flop preferentially in the desired direction. The flanges of the embodiments disclosed in US3705566 comprise complex mouldings which make the marker uneconomic to produce in practice.

We have found that, by careful control of the configuration of a highway marker, and of the properties of the materials from which it is made, it is possible to produce a marker in an economical manner, which is capable of self-righting even from the fully tipped position (i.e. with the upstanding member in contact with the ground).

According to the present invention there is provided a highway marker comprising an upstanding member and a flange fitted to the lower end of the upstanding member, the flange comprising a sheet of elastomeric material which is of substantially constant thickness throughout, and the upstanding member extending substantially centrally from the flange, the construction being such that, when the flange stands on a level surface and the upstanding member is tipped into contact with the surface, a portion of the flange remains flat on the surface and the centre of gravity of the remainder of the marker is situated directly over the said portion, the tipping moment exerted by the centre of gravity about the line at which the flange meets the surface being less than the restoring moment exerted by the resilience of the flange, whereby the marker is self-righting from the tipped position.

The upstanding member may be of any desired configuration, for example it may be conical or cylindrical, and it is preferably made from a lightweight material such as low-density polyethylene. The properties of the flange are, of course, very important, but satisfactory results have been achieved using elastomeric material, such as natural or synthetic rubber, having a Shore A Hardness between 55 and 85 (more preferably between 60 and 70), and with a rebound resilience of 40% to 90% (preferably between 40% and 80%). The thickness of the flange will depend, to some extent, on the properties of the material used, but may, for example, be between 5 and 15mm, for example 1Omm. This is much thinner than the bases of conventional traffic cones, and has the beneficial result that the marker is less prone to being dislodged or turned over by vehicles running over the flange.

British Standards for highway markers require the base of a marker to lie wholly within a circle having a diameter which is 75% of the height of the marker.

Thus, for a traffic cone with a height of im, the base must lie within a circle having a diameter of 750mm.

In an embodiment in accordance with the present invention, the flange is in the form of a regular hexagon, with a distance between opposite apices of 750mm for a 1m cone. Thus this embodiment will comply with the British standard, even if the word "base" is interpreted as covering the flange.

The upstanding member of the marker preferably has, at its lower end, a circumferential groove in which the flange is fitted. The lower wall of the groove preferably slopes downward and outwardly in order to lead the material of the flange towards the surface on which the marker stands. Consequently, the material of the flange will lie flat against the surface over as large an area as possible. This provides two added benefits. Firstly, the large contact area between the flange and the surface on which the marker stands increases the resistance of the marker skidding or sliding across the surface, for example under the influence of the slipstream of vehicles. Secondly, the flange acts in the manner of a suction pad, and will thus cling to the surface under the effect of suction generated within the cone if an attempt is made to lift it or to tip it over. Thus, the marker is not only self-righting, but is more difficult than are conventicnal markers to tip over in the first place. In order to prevent this suction effect from causing problems when the marker is to be moved deliberately, a vent hole, for example at the top of the marker, may be provided in order to release the suction if the marker is to be lifted from the surface.

In the event of sudden impact with the cone, however, flow of air through the vent hole will, in many cases, be too slow to allow the marker to be detached from the surface.

For a better understanding of the present invention, and to show how it may be. carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which Figure 1 is a diagrammatic sectional side view of a traffic cone; Figure 2 shows the traffic cone of Figure 1 in a tipped postion; and Figure 3 is a plan view of the upright cone of Figure 1.

The traffic cone comprises an upstanding conical member 2 and a flange 4. The conical member 2 is a rotationally moulded component made from a low density plastics material, such as polyethylene. It terminates at an end wall 6 at its top end, this wall 6 having a central hole 8. Although not shown in the drawings, the hole 8 may receive, for example a closure or a handgrip. At its lower end, the member 2 has a circumferential groove 10 defined between a rib 12 and a lower lip 14. The lower end of the member 2 is open.

The flange 4 comprises a sheet of elastomeric material of relatively high density. The flange 4 may be made by cutting a larger sheet to shape, but it is preferred to make the flange 4 by moulding, in order to reduce wastage of material. While the flange 4 may be moulded flat, it may alternatively be slightly domed in order to increase the stiffness in the stressed condition. As shown in Figure 3, the flange 4 is in the form of a regular hexagon, with a central hole.

The member 2 extends through the hole, and the flange is received within the groove 10.

The upper surface of the lip 14, which forms the lower wall of the groove 10, is inclined downwardly in the radially outwards direction so as to lead the flange 4 on to the surface 16 (which would normally be a highway) on which the marker is placed.

Figure 2 shows the cone tipped over so as to bring the top end of the member 2 into contact with the surface 16. The flange 4 is flexed at 18 leaving a region 20 of the flange flat against the surface 16.

The upper portion 22 of the flange 4 extends upwardly.

It will be appreciated from Figure 2 that, when the marker is tipped right over, the lower edge of the member 2 is not vertical, but slopes, from bottom to top, towards the top end of the member 2.

Consequently, the region 22 of the flange 4 will tend to deflect slightly towards the top end of the member 2, as shown in Figure 2. However, the flange 4 is sufficiently rigid to minimize this deflection of the region 22, with the result that the region of the flange 4 above the flexed region 18 lies substantially in a single plane.

In Figure 2, the centre of gravity CG of the marker, excluding the region 20 of the flange, lies directly over the region 20.

The thickness of the base 4, and the properties of the material from which it is made, are selected so that the energy recoverable from the flexing of the material at 18 is greater than the energy required to raise the marker from the position shown in Figure 2 to a position in which the centre of gravity CG lies to the left of the line 24 at which the flange.4 meets the surface 16. Once this condition is reached, the weight of the marker acting through the centre of gravity CG will exert a righting moment about the line 24, and this moment will then supplement the resilience of the flange 4 in tending to right the marker.

It will be appreciated that various combinations of parameters will provide the self-righting effect.

However, two specific examples are given in the Table below.

Cone A Cone B Height 1 metre 750 mm Flange dimension (apex to apex) 750 mm 750 mm Flange thickness 9.5 mm 9.5 mm Shore A Hardness of flange material (ISO/R868) 66 63 Rebound resilience of flange material (BS903 Part A8 Method A) 45.8% 74.3%.

It will be appreciated that the flange dimension of cone B falls outside the limit set for the base in the relevant British Standard. However, cone B was assembled using an existing upstanding member 2, to which a flange 4 of the required size was fitted in order to produce the self-righting characteristic. If a smaller flange were used with the same upstanding member 2, the centre of gravity CG would be outside the periphery of the region 20 of the flange when the cone was tipped. A self-righting cone with a height of 750 mm and a flange within the British Standard requirements for the bases of traffic lines (i.e. with an apex to apex dimension of not more than 562 mm) could be produced by modifying cone B to move the centre of gravity CG further to the left, as shown in Figure 2.This could be done, for example, by altering the weight distribution of the member 2, or by increasing the weight of the flange 4.

Furthermore, it is not certain that the flange is correctly identified with the "base" referred to in the British Standard, since it is a separate component, of small thickness, fitted to the main body of the cone.

It will be appreciated from Figure 1 that the base 4, owing to its flexibility, makes intimate contact with the surface 16. In fact, the base 4 substantially prevents the flow of air into and out of the member 2 through the bottom of the member 2. Consequently, if an attempt is made to lift the marker from the surface 16, or to tip the marker over, suction is generated within the member 2 which tends to prevent the base 4 from being lifted. The suction is relieved by the flow of air into the member 2 through the opening 8, but this takes some time. Thus, while the marker can be lifted from the surface 16 by pulling it upwards, the marker will be able to withstand minor impacts without being dislodged or tipped over.

Claims (17)

1. A highway marker comprising an upstanding member and a flange fitted to the lower end of the upstanding member, the flange comprising a sheet of elastomeric material which is of substantially constant thickness throughout, and the upstanding member extending substantially centrally from the flange, the construction being such that, when the flange stands on a level surface and the upstanding member is tipped into contact with the surface, a portion of the flange remains flat on the surface and the centre of gravity of the remainder of the marker is situated directly over the said portion, the tipping moment exerted by the centre of gravity about the line at which the flange meets the surface being less than the restoring moment exerted by the resilience of the flange, whereby the marker is self-righting from the tipped position.

2. A highway marker as claimed in claim 1, in which the upstanding member is conical.

3. A highway marker as claimed in claim 1, in which the upstanding member is cylindrical.

4. A highway marker as claimed in any one of the preceding claims, in which the upstanding member is made from a lightweight material.

5. A highway marker as claimed in claim 4, in which the upstanding member is made from low-density polyethylene.

6. A highway marker as claimed in any one of the preceding claims, in which the flange is made from natural or synthetic rubber.

7. A highway marker as claimed in claim 6, in which the rubber has a Shore A Hardness between 55 and 85.

8. A highway marker as claimed in claim 7, in which the rubber has a Shore A Hardness between 60 and 70.

9. A highway marker as claimed in any one of the preceding claims, in which the material of the flange has a rebound resilience of 40% to 90%.

10. A highway marker as claimed in claim 9, in which the material of the flange has a rebound resilience of 40% to 80%.

11. A highway marker as claimed in any one of the preceding claims, in which the thickness of the flange is between 5 and 15mm.

12. A highway marker as claimed in any one of the preceding claims, in which the flange is in the form of a regular hexagon.

13. A highway marker as claimed in claim 12, in which the distance between opposite apices of the hexagon is 750mm and in which the height of the upstanding member is 1 metre.

14. A highway marker as claimed in any one of the preceding claims, in which the upstanding member of the marker preferably has, at its lower end, a circumferential groove in which the flange is fitted, the lower wall of the groove sloping downwardly and outwardly in order to lead the material of the flange towards the surface on which the marker stands.

15. A highway marker as claimed in any one of the preceding claims, in which the flange is adapted to act in the manner of a suction pad.

16. A highway marker as claimed in claim 15, in which a vent hole is provided in order to release the suction during deliberate lifting of the marker.

17. A highway marker substantially as described herein with reference to, and as shown in, the accompanying drawings.