GB2451283A - Rigid plastic insert for road stud base unit - Google Patents

Abstract

The rigid plastic insert comprises a substantially flat base 960, a mounting portion substantially perpendicular to the base for supporting one or more reflectors 970 facing towards the front and/or rear of the insert, and two opposing winged portions 980A,980B, one each side of the mounting portion, that are substantially flat, perpendicular to both the base and the mounting portion and which extend further towards the front and rear of the insert than the base. The wing portions are preferably identical to one another and slope downwards from the top 966 of the insert to a point where each wing is furthest from the centre of the insert before sloping back in towards the base of the insert such that the front and rear ends of the winged portions are substantially triangular in shape. The slope of the insert is designed to be the same as the slope of the surrounding base unit within which the insert is placed.

Description

ROAD STUD

Field of the Invention

The present invention relates to road studs, and in particular to a plastic reflector insert for a road stud.

Background of the Invention

Road studs are in widespread use to provide visible guidance and warnings to motorists and other road users.

Such road studs typically include one or more reflectors made out of glass or plastic to reflect light from vehicle headlights The road studs help a motorist to determine his or her position on the road during hours of darkness.

There are two main types of road stud in use in the UK. The first is generally known as a "stick on", and is normally formed from a plastic unit incorporating one or more plastic reflectors. Plastic stick-on reflectors are placed on top of the surface of the road and are attached to the road by adhesive. They are relatively cheap but also have a relatively short life-time. For example, they may become detached from the road surface by passing traffic, and/or the visibility of the reflector may become reduced, for example by dirt being deposited onto the surface of the reflector.

The other main type of road stud in use in the UK is a depressible (also sometimes referred to as a "cat's eye"). This comprises a base unit, normally made of cast iron, which holds a resilient insert. The insert is typically made of rubber, and carries one or more glass or plastic reflectors. This type of road stud is installed by drilling a hole in the road, and then bonding the road stud into location using bitumen or some other road grout. The inserts for depressible road studs are generally provided with one or more wiper blades. When the insert is compressed, for example because a lorry has driven over the road stud, these blades are designed to wipe across the reflectors. This helps to keep the surface of the reflectors free from dirt, and hence helps to maintain high visibility. One example of a depressible road stud is described in GB 2263298 B. A road stud generally in accordance with this patent is sold commercially under the "Light Dome" trademark by Industrial Rubber plc, of Fareham, Hampshire.

The typical weight of a conventional base unit made of cast iron is approximately 5 kg. Although the large weight of the base unit assists in retaining the stud in the road, it does mean that the base units are relatively expensive to transport around the country since they are so heavy. In addition, it is difficult to machine lay such heavy road studs. Rather, the road studs are generally laid by manual workers by hand. However, the weight of the stud may cause some safety concerns, for example a base unit might cause injury if dropped onto the foot of a worker GB 2280922 A suggests a base unit formed of a plastic material such as nylon rather than metal. The use of a plastic base is also suggested in GB 2121463 A and GB 2229470 A, as well as in PCT/GBO6/00l883. Such a plastic base unit is very lightweight compared to existing cast iron base units. For example, the plastic base unit of PCTIGBO6/00 1883 has a weight of approximately 500g. This reduced weight helps with transportation and road installation of the base unit -e.g. a plastic base unit might be dispensed by machine from a cassette of base units, thereby offering faster, safer, and more controlled, installation. There is interest in improving road studs that use plastic base units.

Summary of the Invention

One embodiment of the invention provides a rigid plastic insert for a road stud base unit. The rigid insert comprises a substantially flat base, a mounting portion substantially perpendicular to the base for supporting one or more reflectors facing towards the front and/or rear of the insert, and two opposing winged portions, one on each side of the mounting portion. The winged portions are substantially flat and perpendicular to both the base and the IS mounting portion. The two winged portions extend further towards the front and/or rear of the insert than the base.

Having the extended winged portions provides an earlier, and hence lower, point of contact between the reflector insert and the wheel of a passing vehicle, which helps to reduce the strength of the impact on the reflector insert.

In general, the two opposing winged portions have the same size and shape as one another. This ensures a generally symmetrical effect of a passing vehicle on the reflector insert (thereby avoiding any tendency to twist the reflector Insert).

The two opposing winged portions may overhang the base by 6mm or more at the front of the insert. For example, in one embodiment, the two opposing winged portions overhang the base by approximately 1 1mm at the front of the insert.

In one embodiment, the top surface of each winged portion slopes down from the top of the mounting portion to the point of the wing that is furthest to the front or to the back of the insert. This slope then helps to form a ramp for an oncoming vehicle wheel to pass over the reflector insert (and road stud). The angle of the slope is generally configured to match the base unit in which the insert is to be located, so that they can then share the load of the passing vehicle. The angle of the slope to the horizontal is generally between 1 5 and 50 degrees, more conveniently between 25 and 30 degrees.

In one embodiment, the front and rear ends of the two winged portions are substantially triangular in shape.

The bottom surface of each winged portion slopes inwards and downwards from the point of the wing that is furthest to the front or to the back of the insert towards the base. The top surface of each winged portion is level with the top surface of the mounting portion. The winged portions therefore extend approximately the full height of the insert. I,

The wing portions generally have a thickness in the range ito 10mm, most commonly in the range 3 to 5mm. This thickness is generally large enough to provide support for a passing vehicle wheel, but low enough so as not to significantly obscure the reflector on the insert.

The present invention also provides a road stud comprising a base unit and a rigid plastic insert such as described above.

Brief Description of the Drawings

Various embodiments of the invention will now be described in detail by way of example only with reference to the following drawings: Figure 1 is a plan view of a plastic base unit for a road stud in accordance with one embodiment of the invention; Figure 2 depicts a transverse section through the base unit of Figure I along line C-D looking towards B (the rear of the base unit), in accordance with one embodiment of the invention; Figure 3 is a front view of the base unit of Figure 1 (from letter A) in accordance with one embodiment of the invention; Figure 4 is a longitudinal section through the base unit of Figure I along line A-B looking towards C, in accordance with one embodiment of the invention; Figure 5 is a longitudinal section through the base unit of Figure 1, parallel to the section of Figure 4 but along a hne closer to D (but still looking towards C), in accordance with one embodiment of the invention; Figure 6 is an underneath plan view of the base unit of Figure I in accordance with one embodiment of the invention; Figure 7 is an underneath perspective view of the base unit of Figure I (without the base inserts) in accordance with one embodiment of the invention; Figures 8 and 9 are two perspective views of the base unit of Figure 1 (without the base inserts) in accordance with one embodiment of the invention; Figure 10 is a plan view of a plastic base unit for a road stud in accordance with another embodiment of the invention; Figure Ills a longitudinal section through the base unit of Figure 10 along line A-B looking towards C, in accordance with one embodiment of the invention; Figure 12 is a longitudinal section through the base unit of Figure 10, parallel to the section of Figure II but along a line closer to D (but still looking towards C), in accordance with one embodiment of the invention; Figure 13 is a side view of the base unit of Figure 10 (from letter D) in accordance with one embodiment of the invention; Figure 14 is a transverse section through the base unit of Figure 10 along line C-D looking towards A (the front of the base unit), in accordance with one embodiment of the invention; Figure 15 is a transverse section through the base unit of Figure 10, parallel to the section of Figure 14 but along a line closer to B (but still looking towards A), in accordance with one embodiment of the invention; Figure 16 is a rear view of the base unit of Figure 10 (from letter 13) in accordance with one embodiment of the invention; Figure 17 is an underneath plan view of the base unit of Figure 10 in accordance with one embodiment of the invention; Figure 18 is an underneath perspective view of the base unit of Figure 10 in accordance with one embodiment of the invention; Figures 19 and 20 are two perspective views of the base unit of Figure lO in accordance with one ID embodiment of the invention; Figures 21 and 22 are a front and a side view respectively of an example of a plastic reflector for use with the base unit of Figure 10; Figures 23 and 24 are top and bottom isometric views respectively of another example of a plastic reflector insert for use with the base unit of Figure 10 in accordance with one embodiment of the invention; IS Figures 25 and 26 are front and side views respectively of the plastic reflector insert of Figures 23 and 24; and Figure 27 is an off-centre longitudinal section through the reflector insert of Figures 23 to 26.

Detailed Description

Figures 1-9 illustrate a base unit 100 for a road stud in accordance with one embodiment of the invention.

The base unit is designed to receive a depressible insert having one or more reflectors. The base unit 100 is compatible with existing base units and inserts, such as described in GB 2263298 -in other words, base unit lOO accepts inserts made for existing base units. However, base unit 100 is made of a plastic material such as nylon, polycarbonate, or any other suitable material, for example by injection moulding, in contrast to the cast iron base unit of existing road studs The plastic base unit 100 is substannally lighter than existing cast iron base units.

Figure 1 shows a plan view of the base unit 100. For convenience of explanation, the front of the base unit (as perceived by an oncoming motorist) is indicated by the location of letter A, the rear of the base unit by the letter B, and the sides by the letters C and D. It will be appreciated nevertheless that the base unit of Figure I is symmetric, in that B could alternatively be considered as the front and A as the rear. This symmetry supports bi-directional operations, for example if the road stud is to be fitted down a central line of a single carriage-way, in which case the insert can incorporate reflectors for both directions (forwards and backwards). In other locations, such as to demarcate lanes within one carriage-way of a motorway, the insert only needs to be provided with reflectors (or a reflector) facing in the forwards direction, i.e. towards oncoming traffic.

As can be seen in Figure 1, base unit 100 is generally circular, in contrast to existing cast iron base units, which are generally rectangular. It will be appreciated that it is generally easier to make a circular hole in the road than a rectangular hole (drills naturally make circular holes).

The main body of the base unit 100 includes side walls 101 and 102, front portion 106 and rear portion 107.

The base unit further includes a recess 110 defined between side walls 101 and 102 and between front portion 106 and rear portion 107. This recess 110 is used to receive and accommodate the depressible insert. Each side wall includes a pairofprojections l2lA, l2lB, and l22A, l22B that extend into recess 110. The projections 121, 122 are used to retain the resilient insert within recess 110. The insert is sized so that when held in recess 110, it protrudes slightly above the top surface of the base unit 100. As a result, the insert is compressed by any vehicle wheel that passes directly over the road stud, thereby activating the wiper blades within the insert to clean the reflectors (as described in GB 2263298).

The front portion 106 of the base unit 100 is formed with a pair of channels 116 that slope down towards recess 110. The channels 116 help to provide a clear line of sight to the reflectors located on the insert within recess (base unit 110 may be used with an insert having one or more reflectors facing forwards and/or one or more reflectors facing backwards). In addition, the channels 116 also help rainwater to run into recess 110, where it can collect for use in cleaning and lubricating the reflector(s) (as described in GB 2263298). The two channels 116 are separated by ridge 126, which helps to direct rainwater to corresponding ducts in the insert that communicate with the bottom of recess 110, where rainwater can accumulate (such ducts are also described in GB 2263298). The rear portion 107 of the base unit is shaped in the same manner as the front portion 106. In particular, rear portion includes a pair of channels 117, which are separated by ridge 127 The top surface of base unit 100 is provided with an anti-skid or anti-slip pattern 120. The anti-skid pattern 120 helps to ensure that when a vehicle wheel crosses the top surface of base unit 100 protruding from the road, the wheel does not suddenly lose traction or start to skid. The skilled person will appreciate that any suitable anti-skid configuration or texture could be used for this top surface.

As shown in Figure 2, the floor 160 of recess 110 comprises two openings or apertures 161, 162. Aperture 161 extends from side wall 101 towards the centre of recess 110, while aperture 162 extends from side wall 102 towards the centre of recess 110. The size of each aperture is sufficiently large to encompass the projections formed on the corresponding side wall. In other words, opening 161 extends at least as far into recess 110 as projections l2lA and 121B, while opening 162 extends at least as far into recess 110 as projections l22A and 1228.

Base unit 100 may be manufactured using injection moulding (the injection point would typically be in the centre of floor 160). In such a process, apertures 161 and 162 allow base unit 100 to be withdrawn from the mould.

In particular, apertures 161 and 162 avoid the mould becoming in effect locked between the floor 160 of the recess and projections 121, 122.

Prior to use of base unit 100, apertures 161, 162 are closed by respective inserts, so that floor 160 in effect extends the full width of recess 110, from side waIl 101 to side wall 102. This then ensures that recess 110 can retain rainwater for cleaning and lubrication purposes. In addition, closing apertures 161 and 162 also prevents any material from the underlying road, for example grit or bitumen, from entering recess 110 from below the base unit (any such material would then contaminate the rainwater, and so degrade the cleansing action of the insert wiper blades).

In general the inserts can be formed from the same plastic material as the rest of base unit 100, although in some embodiments a different material may be used. The number of inserts to be used corresponds to the number of openings, For example, the embodiment of Figure 1 has two inserts, but other embodiments may use a different number of inserts. The insert(s) can be fixed into the corresponding opening(s) by any suitable technique, for example adhesive bonding, acoustic welding, some form of snap or press fit, an interference fit, and so on.

The skilled person will appreciate that other configurations may be used for the aperture or apertures placed in the floor of recess 160, dependent in part upon the number and location of projections 121, 122 (which may not necessarily be the same as shown in Figure I). For example, one possibility would be to define a separate opening for each projection. This would then lead to four openings for the four projections shown in Figure I, with each of openings 161, 162 in effect being split in half. Another possibility is that the base unit contains only a single aperture that extends across the width of the base unit from side wall 101 to side wall 102. In this embodiment, the single aperture encompasses all the projections (four in Figure I), again permitting removal from an injection mould (Such an embodiment may use front portion 106 and rear portion 107 as twin injection points).

As shown in Figures 4 and 5, the undersides of front portion 106 and rear portion 107 are at least partly excavated. Thus hollow 146 is provided under the front portion 106, and hollow 147 is provided under the rear portion 107. These hollows 146, 147 help to reduce the weight of the base unit and also assist with the moulding process Plastic base unit 100 has to withstand not only fracture but also flexure, otherwise the weight of a vehicle passing over base unit 100 may distort the shape of the base unit. Accordingly, the underside of the front portion 106 of base unit 100 is provided with longitudinal ribbing 216 (see Figures 6 and 7). This ribbing helps to prevent distortion of the base unit 100, and may act in compression or tension, depending upon the type of distortion involved. The same pattern of ribbing 217 is also provided in the excavated region underneath the rear surface 107 of the base unit. It will be appreciated that the precise pattern and configuration of ribbing to protect against distortion may vary from one embodiment to another.

Ribbing 216 and 217 extends from the top of the base unit dowit to the bottom of the base unit -i.e. substantially flush with floor 160. Ribbing 216, 217 provides greater contact of the base unit with the road grout at the bottom of the base unit during installation, thereby helping to hold the base unit in position.

One particular advantage of ribbing 216, 217 is in relation to frogging. Frogging is a process whereby conventional metal base units have the cavities underneath the front and back portions filled with road grout prior to installation. Frogging in this manner ensures that after installation, the front and back portions can transfer weight from passing vehicles through the road grout in the cavities to the ground. In contrast, in the absence of frogging, the cavities would be full of air, and so could not transfer weight in this manner. This would then concentrate any passing weight onto the nm of the base unit, with potential consequential damage for the bedding of the base unit in the road and/or the rim of the base unit itself. However, frogging is a relatively time-consuming and therefore expensive operation.

Ribbing 216, 217 is configured to avoid frogging. In particular, since the ribbing 216, 217 extends down to IS the floor of the base unit from the top surface of the front and rear portions, this ribbing can transfer weight from the top of the base unit to the ground. The ribbing helps to distribute such transferred weight widely across the underneath of the base unit, and so reduces the risk of damage to the bedding of the road stud in the road (or to the road stud itself). Frogging may also be avoided with other patterns of ribbing that extend to the floor of base unit 100.

Projections 121, 122 have an overall shape that is generally similar to the projections on existing cast iron base units (see Figures 8 and 9). However, the projections on existing cast iron base units are solid, whereas projections 121, 122 have a box or hollowed configuration. The use of a box configuration lightens the projections, and helps manufacturing by reducing the rime required for the injection moulding to set (a long setting time may lead to distortion and/or weakness). At the same time, the box profile for projections 121, 122 helps to ensure that the projections are strong enough to retain the resilient insert within the base unit.

In one embodiment, each projection comprises two side walls attached to a floor, where both side walls and the floor extend perpendicularly from the side wall 101, 102 of the base unit, The portion of the projection furthest from the side wall 101, 102 is tapered to reduce the height of the projection. This tapering helps the projection to mate with a corresponding hole in the resilient insert. The top surface of the projection is open. Although Figures 1- 9 depict one particular shape for projections 121, 122, it will be appreciated that many other different shapes or configurations might be used instead The base unit is provided with a lower rim 155 that extends around the circumference or perimeter of base unit 100. Above the lower rim is wall 156, which also extends around the circumference or perimeter of base unit 100. Note that when the base unit 100 is installed into the road, it is sunk at least to the top of wall 156.

The region of waIl 156 corresponding to front portion 106 is provided with four apertures 150 (see Figures 3 and 8). These apertures provide openings or channels from outside the base unit into the cavity 146 underneath the front portion 106. The channels then extend out from the bottom of the base unit via the holes or spaces 166 between ribbing 216 (see Figure 7). Similarly, the region of wall 156 corresponding to rear portion 107 is also provided with four apertures ISO (see Figure 9), which provide openings or channels from outside the base unit into the cavity 147 underneath the rear portion 107 and Out through the bottom of the base unit via spaces 167 between ribbing 217.

Note that the walls of ribbing 216, 217 are aligned so as to alternate with holes 150, thereby separating the holes 150 from one another. As a result, each hole is flanked by a pair of walls, one on each side of the hole. These walls define the charmel from hole 150 out through the opening 166, 167 at the bottom of the base unit. This channel is fully enclosed, in that the input hole ISO is separated from the output hole 166 by rim 155, which is continuous around the base unit. These holes/channels can be moulded by using extraction cores or some other suitable technique. l5

The provision of holes ISO helps to bond base unit 100 to the road. In particular, when the base unit is inserted into a hole with road grout such as molten bitumen, the road grout flows through holes 150 and/or openings 166/167. The road grout fills the corresponding channel, thereby forming a continuous loop around the portion of the rim 155 that separates hole 150 from opening 166/167. These loops in effect lock the base unit to the road; the base unit can only be removed by breaking the loops of road grout, thereby providing a secure attachment of the base unit to the road.

It will be appreciated that there are many possible variations on the arrangement of the holes. For example, rather than just having holes at the front and back of the base unit, such holes can be provided alternatively or additionally on the sides of the base unit, thereby interconnecting with the openings 211, 212 located between ribbing 201, 202. However, since base unit receives most impacts from the front, i.e. from oncoming traffic, the provision of holes 150 on the front and rear portions 106, 107, such as shown in Figures 8 and 9, may be of particular benefit.

Although the base unit 100 shown in Figures 8 and 9 has four holes 150 front and back, other base units may have more or fewer holes. For example, in another embodiment, there are 16 holes evenly distributed around the circumference of the base unit. One factor in the number of holes concerns the size of the individual holes 150 (given that the overall size of the base unit 100 may be relatively fixed by the intended application). The holes must be sufficiently small so as not to weaken unduly the overall structure of the base unit, but also sufficiently large to allow the formation of loops of road grout of reasonable size and strength to help retain the base unit in the road In one embodiment, the holes 150 have dimensions in the range 5-40mm, for example, approximately a I Ox 15mm rectangle.

However, other embodiments may have holes with a different size and/or a different shape -e.g. circular, square or elliptical. Furthermore, one base unit may be provided with multiple holes of differing size and/or shape. in addition, although the base unit 100 has all the holes at the same height above the bottom of the base unit (as defined by rim 155), the height of the holes may vary in some embodiments.

Although ribbing 216, 217 helps to define the channels from holes 150 out through the bottom of the base unit, in other embodiments, such ribbing may be partly or completely omitted (especially if it is not required for strengthening or anti-frogging purposes). For example, if ribbing 216, 217 is completely omitted, the holes 150 in the front portion 106 of the base unit communicate with (shared) cavity 146 underneath base unit, and from there directly with the underside of the base unit. This still permits the formation of channels or tubes of road grout to secure the base unit into the road, albeit with a somewhat different shape or topology. Thus instead of an individual tube of road grout from the side wall to the underside of the base unit for each hole 150, the individual tubes instead pass just through corresponding holes 150 into cavity 146, where they then merge into a single tube or channel opening underneath the base unit.

Figures 10-22 illustrate an alternative embodiment of the invention in which a road stud comprises a plastic IS base unit 500 for receiving a plastic reflector (rather than a depressible). Like plastic base unit 100 of Figure I, plastic base unit 500 comprises side walls 101, 102 which define a recess 110 between front and rear portions 106, 107 for receiving a reflector. The surfaces of front and rear portions 106, 107 of base unit 500 slope in towards recess (analogous to the slope of channels 116 and 117 in base unit 100), thereby providing good visibility of a plastic reflector in recess 110. The tops of side walls 101, 102 are textured to provide an anti-skid or anti-slip surface 120, analogous to the anti-skid surface 120 of base unit 100. As discussed above, this anti-skid surface can have any appropriate shape or texture, and may extend over all or just part of the tops of side walls 101, 102.

As with base unit 100, base unit 500 has holes 150 in the outer rim 156, above lower rim 155. These holes provide channels through to the underneath (cavity) portion of the base unit. When the base unit is installed, road grout can flow through holes 150 to link up with road grout underneath the base unit, thereby holding the base unit securely in the road. In the embodiment of base unit 500 shown in Figures 10-20, there are four holes 150 on each side of the base unit 500 (in contrast to the holes in base unit 100, which are located front and back). The holes 150 of base unit 500 are generally similar in size and shape to the holes 150 in base unit 100. It will be appreciated that the number, size, shape and location of the holes ISO may vary from one embodiment to another. For example, in another embodiment, there are 16 holes evenly distributed around the circumference of the base unit.

Looking at the underside of base unit 500 (see Figures 17 and 18), base unit 500 includes an inner rim 555 which extends to the bottom of the base unit. The floor 160 of recess 110 is connected to the outer rim 155 by radial ribbing, e.g. 616, 617, that extends through the inner rim 555. The inner rim 555 provides support for the front portion 106, the rear portion 107, as well as side walls 101 and 102, and can also provide an anti-frogging function as discussed above (in conjunction with the radial ribbing).

L

Holes 150 communicate with the cavity between the outer rim 155 and the inner rim 555. For example, as shown in Figure 15, hole 150 communicat es with cavity 622 in side wall 102 and cavity 621 in side wall 101, where cavity 622 is cut off from the main cavity 612 under side wall 102 by inner rim 555, and cavity 621 is likewise cutoff from the main cavity 611 under side wall 101 by inner rim 555 However, in other embodiments, the channels formed by holes 150 may extend through the inner rim.

The internal faces of side walls 101 and 102 (i.e. the faces that form opposing walls for recess 110) are profiled to contain an indented portion. In particular, the internal face of wall 101 is provided with a ledge or overhang 501 above recessed or indented portion 57 IA, while the internal face of wall 102 is provided with a ledge or overhang 502 above recessed portion 571B (see Figures 15 and 16) The lines of overhang 501, 502 slope downwards from the back portion of the base unit to the front portion. Thus the region 574A of the indented portion 571A towards the front of the base unit has a low height compared to the depth of the recess 110. Conversely, the height of the Indented portion 571 A rises towards the rear of the base unit so as to clear slope 527. Similarly, the region 574B of the indented portion 571 B towards the front of the base unit has a low height compared to the depth of the recess 110, while the height of the indented portion 571 B rises towards the rear of the base unit so as to clear slope 527. The angle of overhang lines 501, 502 is such that they are approximately parallel to slope 527, thereby defining channel 578A on side wall 101 and channel 578B on side wall 102. Channel 578A communicates with indented portion 57lA at one end, and runs Out from recess 110 to the rear of the base unit 500 at the other end.

Channel 578B communicates with indented portion 571 B at one end, and runs out from recess 110 to the rear of the base unit 500 at the other end.

Recessed portions 57 IA, 571B are used to retain a plastic reflector insert 900, such as shown in Figures 21 and 22, within the base unit 500. The reflector insert comprises a base 910 and a reflector 920 mounted on an upright support portion 915 attached to the base 910. The reflector 920 may comprise any suitable form of retlector, such as tape, plastic retroreflector, and so on. The base 910 is slightly wider than the upright support portion 915 (as shown in Figure 21).

The plastic reflector insert 900 is inserted into base unit 500 by slotting the side edges of base 910 into opposing channels 578A, 578B from the rear of the base unit 500. The reflector base 910 is then moved forwards, approximately parallel to slope 527 along channels 578A, 578B, until the rear (trailing) portion of the base 910 reaches recess 110, i.e. clears slope 527. The reflector insert 900 can now fall (rotate) so that its base 910 lies flat on the floor 160 of recess 110.

The reflector insert 900 can be readily removed from base unit 500 by performing the opposite action to that used to insert the reflector into the base unit. In particular, the rear portion of the reflector insert 900 is rotated upwards until the base 910 is generally parallel with channels 578A, 578B. The reflector insert 900 can now be removed from the base unit by sliding the reflector insert out along channels 578A, 578B to the rear of base unit 500. l0

Note that in this embodiment, insertion and removal of the reflector insert does not involve any deformation of the insert However, such deformation may potentially be invotved in other embodiments (in addition to the rotation and translation).

On the other hand, contact between a vehicle wheel and the reflector insert 900 is extremely unlikely to remove the reflector insert 900 from base unit 500. Thus if a vehicle hits base unit 500 and reflector insert 900 from the front, i.e. from direction A, this will tend to lift the front portion of the reflector insert base. However, such movement of the reflector base 910 is rapidly resisted by the lowest regions 574A, 574B of indentations 57 IA, SuB.

Alternatively, if the reflector unit is hit from the rear, i.e. from direction B, this may rotate the reflector base 910 so that its rearedge is lifted or rotated from the floorofthe recess 160 until it reaches overhang 501, 502. In this configuration, the reflector insert base 910 is now parallel with channels 578A, 578B, as it would be for manual removal such as described above. However, it will be appreciated that in this situation, the vehicle passing over the base unit will tend to urge the reflector insert 900 towards the front of the base unit 500 -i.e. in the opposite direction to the force needed to remove the reflector insert 900 by sliding it out along channels 578A, 578B. It can therefore be seen that the configuration and combination of recessed portions 57 IA, 57 lB and channels 578A, 578B provides a secure housing for the reflector insert 910 within base unit 500. Thus base unit 500 prevents the reflector insert 900 from being accidentally removed by passing traffic, while still allowing for removal of the reflector for service or maintenance purposes.

Although base unit 500 has just a single channel (on each side wall) for receiving reflector insert 900, it will be appreciated that more complicated profiles could be used instead for side wall 101 and/or side wall 102. For example, one or both side walls might be profiled with multiple channels, ridges etc. Such a profile pattern could be used to provide more secure engagement and positioning of a reflector insert, and/or to be able to accommodate multiple different designs, heights and/or positions of reflector insert.

In one embodiment, base unit 500 is approximately 150 mm in diameter and approximately 39 mm high.

Recess 110 is approximately 50.5 mm long (front-to-back), 57 mm wide, and IS mm deep (from floor 160 to the lowest edge of front and rear slopes 526, 527. The overhang along lines 501, 502 is approximately 4.5 mm, and the height of channels 578A, 578B is approximately 3.5 mm. However, it will be appreciated that these dimensions are provided by way of example only, and many other dimensions (and shapes) might be used for base unit 500 In one embodiment, base unit 500 is made in two halves via injection moulding. One half forms the left side of the base unit, the other half forms the right side (when viewed by approaching traffic). These two halves can then be bonded together down a vertical plane containing the longitudinal axis of the base unit (by any suitable bonding technique).

II )

It will be appreciated that the exact choice of plastic material for the base unit (of any of the described embodiments) is dependent upon considerations such as impact resistance, wear resistance, and environmental resistance (e.g. in respect of sunlight and rain). This may lead to different plastic materials being used in different locations. For example, the geographical location of a road stud affects the amount of rain, sunshine, temperature, and other environmental factors experienced by the road stud. Similarly, the positioning of a road stud within the road and the pattern of traffic using the road affects the amount of wear experienced by the road stud. Consequently, it may be appropriate to use different plastic materials having different wear, impact and environmental resistance to provide the most durable road stud for any given location.

Ii is also possible to add a colourant to the plastic material for the base unit of any of the described embodiments in order to make a coloured base unit. Thus for existing road studs, some of the reflectors are coloured.

For example, it is common to use white reflectors to indicate the internal lanes of a motorway, green reflectors to indicate a slip road leaving the motorway, red reflectors to indicate a slip road joining a motorway (thereby warning a motorist not to turn at this junction), and amber reflectors to indicate the sides of the motorway carriage-way.

By adding a colourant to the plastic material for the base unit, the colour of the base unit can be made to match the colour of the reflector(s) -e.g. a white, amber, red, or green base unit, as appropriate. With this approach, the colour of the base unit, which has a relatively large exposed surface area, would primarily be visible during daylight, and the colour of the reflector primarily visible at night-time. One advantage of using a colourant to incorporate colour into the material of the base unit (rather than just applying the colour to the base unit as a surface coating, such as by painting), is that the base unit retains the colour even if the exposed surface of the base unit suffers wear due to passing traffic.

In some embodiments, a luminescent colourant or dopant is added to the plastic so that the base unit luminesces (e.g. fluoresces or phosphoresces), for example in response to passing car headlights. This would then allow the base units themselves to be visible at night-time, which would be especially helpful for improving the visibility of road studs outside a direct headlight beam, such as on corners or for cyclists.

A further possibility is to colour the resilient insert of a road stud to match the reflector and/or the base unit.

Existing depressible inserts are generally white, but these could be coloured as appropriate, using some suitable material or surface treatment for the insert. It will also be appreciated that rather than providing matching colours for the reflectors, base unit and/or insert, contrasting colours could be used instead. This contrast may help with the visibility and noticeability of the road stud in appropriate circumstances.

Figures 23 to 27 depict a reflector insert 950 for inserting into the base unit 500 of Figures 10 to 20 in accordance with one embodiment of the invention (in other words, reflector insert 950 is an alternative to using the reflector insert of Figures 21 and 22). The reflector insert 950 comprises a substantially flat base 960, which is fitted into base unit 500 in the same way as described above for reflector insert 900.

An upright portion 965 rises up from base 960 and is used to support plastic reflector(s) 970 (analogous to the plastic reflector 920 used with the reflector insert 900). Reflector insert 950 may be provided with one or two plastic reflectors 970, depending upon whether bi-directional (front and back) or just uni-directional (front only) operation is required. The reflector insert 950 is otherwise symmetrical front/back and also from side to side.

The upright portion 965 of insert 950 is substantially longer (in the front-back direction) compared to the upright portion 915 of the base unit 900 of Figures 21 and 22. This results in a longer top surface 966 for the reflector insert 950.

As can be seen in Figure 24, the underside of the reflector insert 950 is excavated to provide two holes, 967A and 967B. These holes help to lighten the reflector insert 950 and also assist with the moulding process as the IS plastic solidifies.

The reflector insert 950 is flanked by winged portions 980A, 980B, one on each side of the upright portion 965. Each winged portion is substantially flat (in a vertical plane) and approximately hexagonal in shape. The top surface of each winged portion lies along the top surface 966 of the upright portion, while the bottom surface of each winged portion lies along the base 960.

The front of each winged portion comprises an apex 985 (see Figure 26) formed by a first surface 983 running downwards and forwards from the top surface 966 of the reflector insert and a second surface 982 running upwards and forwards from the base 960. The back of each winged portion has a corresponding (symmetrical) shape.

Note that apex 985 overhangs the most forward point 961 of base 960. In other words, the winged portions 980A and 980B extend further forwards than the base 960. Similarly, the winged portions 980A and 980B also extend further backwards than the base 960.

The angle of slope 983 on the winged portions 980A, 980B is arranged to match the slope on the raised portion of base unit 500 (in particular slope 589 as indicated in Figure II). The profile of the reflector insert 950 (as per Figure 26) generally matches the profile of the base unit 500 (as per Figure Il), so that the top of the reflector insert 950, including top surface 966 and sloping surface 983, is generally level with the corresponding portion of base unit 500. Note that since the winged portions therefore generally track and are close to the internal walls of the base unit 500, and because the winged portions are also comparatively thin, their presence has relatively little impact on the angle of visibility of the plastic reflector 970. 1)

The provision of winged portions 980A, 980B for the reflector insert 950 increases the stability and robustness of the reflector insert. This can be understood by first considering what happens when the tyre of a passing vehicle makes contact with the reflector insert 900 shown in Figures 21 and 22. In particular, the top portion 915 of the reflector insert 900 is pushed forwards, which tends to rotate the reflector insert 900 forwards. This forwards movement is resisted by the action of the side walls 501, 502 on the base 910 of the reflector insert 900 (as previously described). However, this causes stress at the join between the upright portion 915 of the reflector insert 900 and the base, since these two components are being pushed in different directions.

In contrast, when a tyre reaches the reflector insert 950 of Figures 23 to 27, the tyre firstly engages the slanting surfaces 983 of the two opposing winged portions 980A, 980B. The position of this contact relative to the centre of mass of the reflector insert 950 reduces the rotational force exerted on the reflector insert 950 (compared to contact with the reflector insert 900). In particular, the point of contact is lower and further forward for reflector insert 950 than for reflector insert 900.

Furthermore, the slanting surfaces 983 of the winged portions 980A, 980B also experience a downward pressure from the passing tyre, which helps to retain the reflector insert within the base unit 500. The internal forces experienced by reflector insert 950 as a result of a vehicle wheel passing over the insert are therefore significantly decreased compared to the situation with reflector insert 900. This helps to improve the longevity of reflector insert 950 in the base unit.

In one embodiment, the overhang of apex 985 (the forwardmost and rearmost points on the winged portions 980A, 980B) compared to the point 961 of the base 960 of the reflector insert 950 is approximately 11mm. It can be seen that this overhang helps to bring forward (and therefore also lower) the first point of contact between the reflector insert and a passing vehicle wheel. This in turn reduces the internal forces experienced by the reflector insert 950 for the reasons given above. However, this is achieved without increasing the footprint of the base 960 (which would otherwise require a larger base unit 500, and therefore a larger hole to be drilled in the road, thereby complicating the installation process).

In one embodiment, the downwards slope 983 on the winged portions 980A, 980B is in the range 25-30 degrees (to the horizontal). As previously indicated, this angle is arranged to match the slope on the base unit 500, and accordingly other embodiments may have slopes at a different angle (depending in part on the base unit for which they are intended).

In conclusion, although a variety of embodiments have been described herein, these are provided by way of example only, and there are many further possible combinations of the features of the different embodiments or additions thereto. For example, although the reflector insert described herein has bi-directional winged portions (for ease of use), the main benefit of the winged portions is obtained from section of the wing facing forwards (i.e. Th towards incoming vehicles); hence the winged portions may not extend towards the back of the insert. Many such variations and modifications on the described embodiments will be apparent to the skilled person and fall within the scope of the present invention, which is defined by the appended claims and their equivalents.

Claims (16)

1. Claims I. A rigid plastic insert for a road stud base unit, the rigid insert comprising: a substantially flat base; S a mounting portion substantially perpendicular to the base for supporting one or more reflectors facing towards the front and/or rear of the insert; two opposing winged portions, one on each side of the mounting portion, said winged portions being substantially flat and perpendicular to both the base and the mounting portion, wherein the two winged portions extend further towards the front and/or rear of the insert than said base.
2. 2. The insert of claim 1, wherein the two opposing winged portions have the same size and shape as one another.
3. 3. The insert of claim I or 2, wherein the two opposing winged portions overhang the base by 6mm or more at the front of the insert.
4. 4. The insert of claim 3, wherein the two opposing winged portions overhang the base by approximately 11mm at the front of the insert.
5. 5. The insert of any preceding claim, wherein the top surface of each winged portion slopes down from the top of the mounting portion to the point of the wing that is furthest from the centre of the insert.
6. 6. The insert of claim 5, wherem the angle of said slope is between IS and 50 degrees.
7. 7. The insert of claim 6, wherein the angle of said slope is between 25 and 30 degrees.
8. 8. The insert of claim 5, wherein the angle of said slope is configured to match a base unit in which the insert is to be located.
9. 9. The insert of any preceding claim, wherein the bottom surface of each winged portion slopes inwards and downwards from the point of the wing that is furthest from the centre of the insert towards the base.
10. 10. The insert of any preceding claim, wherein the top surface of each winged portion is level with the top surface of the mounting portion.
11. II, The insert of claim 10, wherein the winged portions extend substantially the full height of the insert.
12. 12. The insert of any preceding claim, wherein the wing portions have a thickness in the range Ito 10mm.
13. 13. The insert of claim 12, wherein the wing portions have a thickness in the range 3 to 5mm.
14. 14. The insert of any preceding claim, wherein the front and rear ends of the two winged portions are substantially triangular in shape.
15. 15. A road stud comprising a base unit and a rigid plastic insert according to any preceding claim.
16. 16. A reflector insert for a road stud substantially as described herein with reference to the accompanying drawings.