GB2448490A

GB2448490A - Road marking device

Info

Publication number: GB2448490A
Application number: GB0707258A
Authority: GB
Inventors: Ian Durant
Original assignee: Prismo Road Markings Ltd
Current assignee: Prismo Road Markings Ltd
Priority date: 2007-04-16
Filing date: 2007-04-16
Publication date: 2008-10-22
Also published as: GB0707258D0; WO2008125886A1

Abstract

The marking device, primarily for forming road markings, comprises an agglomeration of retroreflective pieces 36 held together by an adhesive 38 which is gray. The adhesive preferably includes reflective elements which may be metallic flakes, e.g. formed from aluminium. The reflective elements are preferably less than 2 microns in length. Also claimed is a marking arrangement, a method of marking and a method of using a road marking arrangement.

Description

MARKING

The present invention relates to a marking device, marking arrangements, a method of marking and a method of using road marking.

It is known to lay a red or green coloured layer on to a road to indicate, for instance, that there is a bus lane or a cycle lane. During both night and day this difference is apparent. it is also known to add evenly distributed retroreflective devices into such coloured layers to empl-iasjse the bus or central hatchings at night.

However the information imparted to the driver is the same and is required to be the same regardless of the time of day.

Us 3 254 563; 4 609 587, 6 398 369; 3 043 196; 5 942 280, DE 1952 1947; EP 0 322 671 and GB 2 164 762 all disclose retroreflective articles. The applicants own earlier publication numbers GB 2 389 615, GB 2 402 694 and GB 2 425 557 also disclose retroreflectjve devices and methods of applying such devices to road surfaces and the content of these applications is hereby incorporated into the present application.

It is an object of the present invention to attempt to overcome at least some of the above or other problems.

According to one aspect of the present invention a marking device including an agglomeration of retroreflective pieces, each agglomeration being held together by adhesive is characterised by the adhesive including gray.

The adhesive may be a gray adhesive.

Where the term "gray" is used in this specification it may include any shade between white and black as well as black itself. The term may also include any Pantone colour of 400 or more or 400 to 440 or 400 to 454 and/or any Pantone Black such as Black or Process Black or Black 2 or Black 4 and/or any Pantone Gray such as Cool or Warm Gray and/or any Cool Gray such as Cool Gray 2 to Gray 9 and/or any Warm Gray such as any of Warm Grays 2 to 9.

For the RGB colour scale the term "gray" may also include Gray 0 to Gray 100 or Gray 0 to Gray 50 or Gray 0 to Gray 30. The term also includes any shade that will cause light of a different appearance to that of the adhesive to be reflected such as predominantly white light including solely white light being reflected from retroreflectjve pieces.

Where the terms "like" or "in keeping with" are used herein to include shades that resemble each other or that fit in with each other or that are not too dissimilar from each other or that are similar to each other as well as identical shades.

The metallic bits assist in the reflection and the greater their lustre or surface integrity, the more the light is reflected.

The adhesive may include reflective bits which may be less than 2 or less than 1 or less than 0.5 or more than 0.5 or more than 0.1 or in the region of 0.2 in the direction of their maximum extent. The bits may be spherical.

The bits may be covered pieces such as mica which may be coated with metal.

That ratio of the maximum extent of a retroreflectjve piece to the maximum extent of a retroflectjve bit may be more than 50:0.0001 or more than 80:0.0001 or more than 100:0.0001.

The present invention also includes a marking arrangement including a plurality of agglomerations as herein referred to. The agglormerations may be spaced from each other. The ratio of the distance between each agglomeration and its nearest neighbour and the maximum extent of an agglomeration may be less than 50:1 or less than 30:1 or less than 20:1 or less than 10:1 or more than 1:1 or more than 2:1 or in the region of 3:1.

The agglomerations may be arranged to impart information to a road user such as by highlighting an area of the road or, alternatively or additionally, by varying the information imparted to a road user when the road user receives light reflected from agglomerations as compared to when no light is reflected from the agglomerations, for instance to narrow a section of the road or to vary the speed limit.

The agglomerations may be arranged to reflect back white light.

The present invention can be carried into practice in various ways but one embodiment will now be described, by way of example and with reference to the accompanying drawings, in which:-Figure 1 is a plan view of a layer 10 for use in a road surface; Figure 2 is a sectional side view of Figure 1 showing the layer 10 alongside a conventional road surface layer 20; Figure 3 is a cross-section through a retroreflectjve device used in the layer 10; Figure 4 is a detailed view of part of a retroreflective device showing the reflection of a light beam; and Figures 5, 6 and 7 are schematic views of road layouts using the layer 10.

As shown in Figures 1 to 3, the layer 10 includes retroreflective devices or clusters 30 spaced from each other. Aggregate 32 also forms part of the surface. The layer 10 is formed by first spreading a resin 34 such as an epoxy resin, with a squeegee or doctor blade, over the surface of a road, then adding the devices 30 such that part of the devices 30 are trapped by the resin with part of the devices protruding from the resin. Then the aggregate 32 is added. The resin then sets and the excess aggregate is swept off the surface.

The devices 30 may be formed as described in our co-pending GB publication numbers 2 389 615 and 2 425 557, the contents of which are hereby incorporated.

As shown in Figure 3, a retroreflectjve device 30 is manufactured by binding a plurality of spherical glass beads 36 of a desired size with an adhesive 38 so as to form a spherical or ovoid agglomeration or cluster 30, preferably 2 to 4 or 6 mm in diameter (although other sizes may be useful according to the application). The size of the glass beads 32 is preferably selected to be within one of the following ranges: from 100 microns to 300 microns, from 200 microns to 400 microns, or from 400 microns to 700 microns, although larger beads may also be used to form agglomerations where appropriate. In this example, two different sizes of glass beads are used, however, in many instances it will be preferably to use glass beads of a single uniform size.

The adhesive 34 may, for example, be epoxy resin, acrylic, polyurethane or hot melt adhesive.

The cluster 30 of beads 36 so formed has retroreflective properties as its surface is made up of a number of glass spheres in close packed formation throughout the cluster presenting a large number of reflecting elements. Light entering a bead 36 is reflected internally of the bead or internally from the resin and re-emitted in the direction of the source.

The light returning to the source (e.g. the vehicle) can be modified in colour by using a pigmented adhesive to bind the beads together. The pigmented adhesive forms a coloured backing to the glass beads. Light entering the glass beads 36 is subject to internal reflection and allows some diffusion into the pigmented adhesive. By this means the light colour may be modified by the effect of the pigmented adhesive and is thus modified before it returns in the direction of the source. The adhesive material 38 may be pigmented with white, red, yellow or green, to produce a reflected colour as required.

Alternatively, the glass may itself be coloured to modify the light, either by the chemical composition of the glass or by a suitable coating treatment. By this means the bead clusters 30 may be used in road markings and other road surfacing to produce a coloured appearance as an aid to driver safety and to provide information about road layout and possibly hazardous situations. Alternatively the adhesive may be gray, which includes black, in shade.

The colour or shade of the adhesive may correspond generally to the colour of the adjacent surface 20.

The properties of the glass used to make the beads 36, such as its chemical formulation, may be varied to achieve a greater degree of reflectivity. In particular, glass of different refractive index, for example values of 1.5, 1.9 2.1 and 2.3, may be used, since glass beads 36 manufactured from higher refractive index glasses return more light and therefore improve the retroreflective performance. Additionally, a mixture of glass beads of different refractive indices may be used.

At night the exposed part of the bead clusters 30 can become illuminated with light from head lamps of vehicles and reflect light back to the driver. The bead clusters embedded into the surface are firmly held by the resin, the surface structure of each cluster 30 being textured by the presence of glass beads 36 so that the resin is absorbed into the textured surface of the cluster 30, this keying effect increasing retention and strength of adhesion of the bead cluster 30.

As mentioned above, the size of the cluster 30 is usefully in the range from 2mm to 4mm diameter; however, larger or smaller clusters 30 may be used in accordance with the thickness of the resin or coating for which they are intended and the degree of embedment. Thus a road marking paint line nominally 500.im in thickness could use clusters 30 in the size range 1mm to 2mm diameter, whereas a thicker line such as a thermoplastic or cold setting resin nominally 1mm in depth would require clusters 30 of 4mm to 6mm diameter to be effective.

An alternative use of the retroreflective devices 30 would be in a road surface dressing, coloured road surfaces for hazard warning, or on vertical surfaces, for example safety barriers, road signs (vertical), etc. These applications would require a relatively low thickness of binder material to allow a large exposed area of reflective material. Such usage requires a particularly strong and durable binder to hold the clusters 30 to the substrate, for example (but no exclusively) two component materials epoxy resin, acrylic and polyurethane.

Rather than being applied on a surface, the retroreflective devices 30 can also be advantageously used in premixed additives to a road marking material, in a quantity proportional to the thickness of the coating to be applied, the devices becoming exposed as the road marking material wears away.

The resin 38 has aluminium leafs or flat flakes or non-leafing aluminium 38 distributed throughout which may be of 0.2 micron in diameter. As shown in Figure 4, a light beam 40 from a car headlight enters the bead 36 and is refracted through the surface. Part of the light then is refracted into the resin 38 and part is then reflected by the bead and by the aluminium back through the bead in the direction of the line 42. The lines 40 and 42 are almost parallel. In this way the driver of the car emitting the beam receives light back from the layer 10.

The layer 10 includes clusters 30 of approximately 6 mm in diameter and approximately half of the cluster is embedded in the resin with half standing proud. The clusters are spaced from each other by between 15 mm to 30 mm, that distance being measured from the periphery of adjacent clusters. The aggregate that is used may be bauxite granite or other types of aggregate suitable for high friction surfacing. The bauxite is not spherical and can have sharp edges. Thus an excellent grip is provided.

The bauxite may have a maximum extent in any one direction of 1.5 mm.

The light reflected back to a driver from gray or black resin is not gray or black but is white. That is because the wavelengths in the visible spectrum are reflected rather than absorbed. Thus, the light appears much brighter than the light reflected from exactly the same layer but with a coloured resin. In a test with a red resin and a gray resin the gray resin was found to reflect between 4 to 5 or more times the amount of white light. That test was performed on an LTL 2000 Retroreflectometer made by Delta in Denmark. The machine was first calibrated using a standard plate. This gave a reading of 151. Then the gray layer was tested at various locations over the layer giving readings of 1391 and 1602 mini candelas/m2/lux. The readings given for the red resin layer were 246 and 263. LTL 2000 Retroreflectometer simulates the retroreflective light at a distance of 30 m.

The layer 10 with the gray resin, when located alongside a like coloured layer 20 or when in keeping with the layer 20 or when of exactly the same colour as the layer 20 results in a driver being unaware during the day of any visual difference or any significant visual difference between the layers 10 and 20. At night though, or when the driver has the lights of the vehicle turned on, a very bright white light will be reflected from the clusters 30 thus dramatically marking the difference. A similar difference will be apparent when a red to resin layer 10 is located alongside a layer 20 of a like or in keeping with or of an identical red layer, although the difference between the layers when reflecting light will not be nearly as dramatic.

Various uses of the layer 10 will now be described with the resin being of gray colour and with the road surface being of the same or a like shade or in keeping with the adjacent surface such that, during the day, the presence of the layer 10 will not be immediately apparent.

Referring first to Figure 5, a motorway 50 is shown having three lanes 52. A slip road 54 is shown from which traffic joins the motorway. In daylight, and in keeping with traditional junctions, white line chevrons 56 are painted at the join to indicate to drivers on the motorway that traffic may be joining from the left and, to indicate to traffic joining, the boundary from which they can join the inner lane 52. Layers 10 according to the present invention are applied between the chevrons 56.

During the day, the road layout and the visual information imparted to drivers remains substantially unchanged. At night though the clusters 30 reflect bright, white light back to drivers both joining the lane as well as those already on the motorway. The required intensity of reflection is 100 millicandelas in the dry, and this level must be reflected after a period of two years. To achieve this level of reflection, the reflective properties of traditional layers must start at -250 milljcandelas With the layer 10 in place, the white light reflected after two years will, it is anticipated, be 500 millicandelas.

Referring now to Figure 6, a road 60 is shown with one lane 62 running in each direction. No overtaking is allowed and so parallel spaced white lines 64 divide the lanes. A layer 10 is applied between the white lines.

During the day the appearance of the road layout will be substantially if not completely conventional. at night though the presence of the white lines will be highlighted through the high intensity white light that will be reflected. If desired, the layer 10 could alternatively or additionally be applied alongside the white lines in the lane that the vehicle is driving along.

Figure 7 shows a curve 70. A lane 72 runs along the outside of the bend 70 and the other lane 74 travels along the inside of the opposite direction. Traditionally, the lanes have been divided by a white line with raised reflective studs dividing the lanes. These studs can be less skid resistant than the normal road surface.

Motorcyles in particular tend to cut the corner and travel over the studs thus resulting in sideways slip. The present invention will maintain the traditional white line 76 and, during the day, the road will present, visually, the same or substantially the same visual appearance.

However, at night, the bend 70 will be radically transformed by reflected light (which reflected light is visible from all directions) . This information is effected as follows: First, a layer bA (which is the same as the layer 10) is applied in a crescent shape on the inside of the white line. This will assist in drivers being further separated from each other at night as drivers travelling in each direction will receive the reflected bright white light.

The layer lOA will also enhance the grip at that part of the road.

Secondly, a layer lOB (the same as the layer 10) is applied in a band on the outside of the bend. This will effectively narrow the width of the outer lane 72 and will encourage speed reduction at night.

Third, the numerals "30" are applied on the approach of each lane 72, 74 to the bend with those numerals having the same composition as the layer 10. Thus, during the day the speed limit may be 60 kmph but at night the speed limit will be 30 kmph. The numerals 30 may first be painted onto the road in resin with the clusters and then the aggregate being applied subsequently. Alternatively a circle, for instance, of resin may be applied with the clusters then being added in the shape of the numerals and with the aggregate then being applied to the whole of the circle of resin.

Consequently traffic can flow at a relatively fast rate during daytime when visibility is good but at a slower rate, encouraged by the width reduction of the outer lane, at night when visibility is poor or in wet conditions at night.

Further, during both day and night, grip in the dangerous middle area of the road is enhanced by the presence of the aggregate.

The markings described are only a selection of some of many different possible markings.

Whilst the distance between clusters 30 has been given, those distances may be greater or smaller.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification

(including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features

disclosed in this specification (including any

accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A marking device comprising an agglomeration of retroreflective pieces, each agglomeration being held together by adhesive characterised in that that adhesive includes gray.

2. A device as claimed in Claim 1 in which the adhesive is gray.

3. A device as claimed in Claim 1 or 2 in which the adhesive includes reflective bits.

4. A device as claimed in Claim 3 in which the bits are metallic.

5. A device as claimed in Claim 3 or 4 in which the bits are flakes.

6. A device as claimed in Claim 4 or 5 in which the bits are aluminium.

7. A device as claimed in any of Claims 3 to 6 in which the bits are less than 2 microns in the direction of their maximum extent.

8. A device as claimed in any of Claims 3 to 7 in which the ratio of the maximum extent of a retroreflective piece to the maximum extent of a reflective bit is more than 50:0.0001.

9. A marking arrangement including a plurality of agglomerations of retroreflective pieces as claimed in any preceding claim.

10. A marking arrangement comprising a plurality of agglomerations of retroreflective pieces, each agglomeration being held together by adhesive, located over a first area with a second area having fewer such agglomerations characterjsed in that the shade of the second area and the shade of the adhesive are like shades.

11. A marking arrangement as claimed in Claim 10 in which the second area is absent of any agglomerations of retroreflective pieces.

12. A marking arrangement as claimed in Claim 10 or 11 in which shades include gray.

13. A marking arrangement as claimed in Claim 12 in which the shades are gray.

14. A marking arrangement as claimed in any of Claims 9 to 13 in which the agglomerations are spaced from each other.

15. A marking arrangement as claimed in Claim 14 in which the ratio of the distance between each agglomeration and its nearest neighbours and the maximum extent of an agglomeration is less than 50:1.

16. A marking arrangement as claimed in Claim 14 or 15 in which the ratio of the distance between each agglomerajn and its newest neighbour and the maximum extent of an agglomeraio is more than 1:1.

17. A marking arrangement as claimed in any of Claims 9 to 16 in which the retroreflective pieces are secured in position using a binder that includes gray.

18. A marking arrangement as claimed in Claim 17 in which the binder is gray.

19. A marking arrangement as claimed in any of Claims 9 to 18 including aggregate that includes gray.

20. A marking arrangement as claimed in Claim 19 in which the aggregate is gray.

21. A marking arrangement as claimed in any of Claims 9 to comprising a road marking arrangement.

22. A marking arrangement as claimed in Claim 21 in which the marking arrangement forms part of a road surface.

23. A marking arrangement as claimed in Claim 21 or 22 in which the agglomerations are arranged in a formation to impart information to a road user.

24. A method of marking comprising locating a plurality of agglomerations of retroreflective pieces held together by adhesive over a first area with a second area having fewer agglomerations characterised in that the shades of the second area and the shade of the adhesive are like shades.

25. A method as claimed in Claim 24 comprising omitting any agglomerations from the second area.

26. A method as claimed in Claim 24 or 25 comprising laying agglomerations that include gray adhesive.

27. A method of marking as claimed in any of Claims 24 to 26 when forming a marking arrangement as claimed in any of Claims 9 to 23.

28. A method of using a road marking arrangement when the marking arrangement is as claimed in any of Claims 9 to 23 or, alternatively or additionally, when the mark has been made by a method as claimed in any of Claims 24 to 27 comprising a road user receiving certain information about the road in daylight and different information when receiving light reflected back from the agglomerations.

29. A method as claimed in Claim 28 in which the reflected light that is received includes white light.

30. A method as claimed in Claim 29 in which the reflected light is white.