Field

[0001 ] The present invention relates to a method and apparatus for applying road surface markings.

[0002] More particularly but not exclusively, the present invention relates to a method and apparatus for applying reflective road surface markings.

Background

[0003] Markings are applied onto the surfaces of roads, pathways and other thoroughfares for a variety of reasons, including to convey official information, warnings, guidance and to delineate reserved and designated areas.

[0004] Road markings are made by firstly applying a marking medium onto the road surface such as, for example, by spraying a water-based paint onto the surface using a pressurised painting gun. Other types of marking medium that are used include hot and cold- applied plastics. Hot plastics are typically heated using a gas-flame to melt the plastic before being applied. Cold-applied plastics are normally pre-mixed with chemicals to trigger a chemical reaction in the material before being trowelled within a pre-laid frame or border.

[0005] Once a marking has been initially applied, retro-reflective glass beads are then commonly dispensed onto the marking so that they embed into the wet paint or plastics material as it dries or cures on the surface. The glass beads enable the road marking to reflect the light from the headlamps of cars and other vehicles during use, significantly improving the visibility and effectiveness of the marking.

[0006] Advances in road marking technology have significantly improved the accuracy, speed and efficiency at which markings can be painted onto road surfaces. As a consequence of this, large sections of freshly painted markings are often left in a vulnerable undried or uncured state for longer periods of time. Markings can easily become damaged or defaced before they have had an opportunity to dry or cure sufficiently, for example due to vehicle 'run-throughs', where paint is picked up by the tyres of vehicles. Wet road markings may also cause damage to the wheels or the underside of a vehicle. [0007] In an effort to solve these problems, additives may be added to the paint or marking medium before it is applied onto the road surface in order to chemically alter its composition and reduce its drying or curing time. These chemical additives are, however, expensive and only lead to a modest improvement in drying times, especially in cold or humid climates. The additives also require additional machinery for mixing the paint and additives together prior to their application onto the road surface which is both expensive and cumbersome to operate. In other attempts to improve the trafficability of road markings in cold climates, thermoplastics have been applied instead of paint. However, it is an expensive alternative, requires additional machinery to heat the thermoplastic up to around 200°C for application, and thermoplastic markings are easily damaged by machinery, such as snowploughs.

[0008] In this context, there is a need for economical and effective methods and apparatus for applying road markings that address the aforementioned disadvantages of conventional methods and apparatus.

Summary

[0009] This application claims priority to Australian Provisional Application No. 2016902541 , filed 28 June 2016, which is incorporated by reference herein in its entirety.

[0010] According to the present invention, there is provided apparatus for applying reflective markings to a surface comprising:

a heating device for heating a plurality of reflective granules;

a mixing device configured to tumble the plurality of reflective granules by rotation of the mixing device;

a dispensing device for dispensing the heated and tumbled solid granules onto a layer of uncured paint or polymer.

[001 1 ] The apparatus may further comprise a paint dispensing device for dispensing the layer of paint or polymer before the reflective granules are dispensed.

[0012] The apparatus may be installed on a vehicle.

[0013] The apparatus may be retro-fitted to a road surface marking vehicle.

[0014] The apparatus may be used for post-processing of the reflective granules after manufacture of the reflective granules.

[0015] The mixing device may be incorporated into the heating device. [0016] The mixing device may comprise a cylindrical tank, wherein a cylindrical axis of the cylindrical tank is aligned horizontally, and wherein the cylindrical tank is rotatable about its cylindrical axis to tumble the plurality of reflective granules.

[0017] The mixing device may comprise at least one internal mixing fin in a tank, wherein rotation of the mixing device comprises rotating the tank and/or the internal fin.

[0018] The internal mixing fin of the mixing device may comprise a corkscrew auger and the axis of the corkscrew may be aligned with a symmetrical axis of the tank.

[0019] The apparatus may further comprise a drive motor for driving rotation of the mixing device in either direction about an axis of symmetry of the mixing device.

[0020] The drive motor may be remotely controllable to control one or both of the direction of rotation and speed of rotation of the mixing device.

[0021 ] The apparatus may further comprise at least one temperature sensor configured to measure one or both of an average temperature of the plurality of reflective granules in the mixing device and an average temperature of the plurality of reflective granules exiting the dispensing device, wherein the temperature measurement(s) is/are used to control one or more of the direction of rotation of the mixing device, the speed of rotation of the mixing device and the heat output of the heating device.

[0022] The apparatus may further comprise a suction device for reclaiming surplus reflective granules from the surface.

[0023] The heating device may comprise a gas furnace positioned outside the mixing device.

[0024] The reflective granules may comprise retro-reflective glass beads.

[0025] The apparatus may be configured to process a mixture of reflective granules and non-reflective granules.

[0026] The dispensing rate of the heated and tumbled reflective granules may be about 200 g/m ² to about 600 g/m ² .

[0027] The dispensing device may comprise an insulated and/or heated feed pipe.

[0028] The present invention also provides a method of applying reflective markings to a surface using the apparatus described, comprising: heating and tumbling a plurality of reflective granules by rotation of the mixing device;

dispensing the heated and tumbled reflective granules onto a layer of uncured paint or polymer on the surface.

[0029] The reflective granules may be heated to an average temperature of about 100°C to about 700°C prior to dispensing.

[0030] The reflective granules may be heated to an average temperature of about 100°C to about 300°C prior to dispensing.

[0031 ] An average temperature of the reflective granules during dispensing onto paint or polymer may be about 80°C to about 250°C.

[0032] The method may further comprise controlling one or more of direction of rotation of the mixing device, speed of rotation of the mixing device, and temperature of the heating device, according to an average temperature of the reflective granules.

[0033] The reflective granules may be dispensed onto the layer of uncured paint or polymer on the surface at a rate of about 200 g/m ² to about 600 g/m ² .

[0034] The step of heating and tumbling the reflective granules may be performed during or after manufacture of the reflective granules, and wherein the granules are dispensed at ambient temperature onto the paint or polymer.

[0035] The present invention further provides a system for applying reflective markings to a surface, the system comprising:

a paint dispensing device for dispensing a layer of paint or polymer onto the surface;

a heating device for heating a plurality of reflective granules;

a mixing device configured to tumble the plurality of reflective granules by rotation of the mixing device;

a dispensing device for dispensing the heated and tumbled solid granules onto the layer of uncured paint or polymer.

[0036] The system may further comprise a reclaiming device for reclaiming surplus reflective granules from the surface. Brief Description of Drawings

[0037] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

Figure 1 is a side elevation view of an apparatus for painting a road, pathway or thoroughfare marking according to one embodiment of the present invention;

Figure 2 is a perspective view of a mixing and heating chamber of the apparatus according to one embodiment;

Figure 3 illustrates the apparatus according to one embodiment installed on a road marking vehicle;

Figure 4 shows test results comparing reflectivity of a mark applied conventionally (left), a retro-reflective raised pavement marker (middle), and a mark applied using an embodiment of the present method;

Figure 5 is a table listing process parameters and results of a trial of the present method;

Figure 6 is a graph illustrating the results of Figure 5;

Figure 7 is a functional specification illustrating control functionality of the apparatus according to an embodiment;

Figure 8 illustrates the temperature sensor of the apparatus according to one embodiment; and

Figure 9 is a perspective view of a mixing and heating chamber of the apparatus according to another embodiment.

Description of Embodiments

[0038] Referring to Figure 1 , there is shown an apparatus for applying a marking on a surface of a road, pathway or thoroughfare, referred to generally by reference numeral 10. The apparatus 10 comprises a first storage container 12 configured to receive a quantity of paint 14. The paint 14 comprises a paint product to be used to paint road surface markings and, preferably, comprises a water-based paint. Alternatively, the paint 14 comprises a hot or cold-applied polymer-based paint product such as, for example, a methyl methacrylate (MMA) acrylic polymer-based paint.

[0039] The apparatus 10 also comprises a device or means for dispensing the paint 14 onto a surface of a road, pathway or similar thoroughfare 20. In the preferred embodiment illustrated in Figure 1 , the device comprises a first feed pipe 16 and nozzle 18 arranged in fluid communication with the first storage container 12. The first feed pipe 16 and nozzle 18 are adapted to dispense the paint 14, eg in the form of spray, onto the surface 20 in a controlled, controllable or continuous manner resulting in an initial marking 22 on the surface 20.

[0040] The apparatus 10 also comprises a second storage container 30 configured to receive a plurality of individual solid granules. Preferably, the solid granules 32 comprise reflective beads such as, for example, retro-reflective glass beads. Examples of retro-reflective glass beads include B-Type (Drop On) beads, C-type (Intermix) beads, D- type (Large Diameter) beads, HR (high reflective) beads, etc. The granules 32 may comprise a mixture of reflective and non-reflective granules. In the illustrated embodiment, this storage container 30 is configured to use an internal gravity feed channel 34 and a second feed pipe 38 arranged in fluid communication with a heating device 41 that contains a third storage container 44. Storage container 44 also acts as a heating and/or mixing chamber.

[0041 ] A control mechanism 36 may be used to adjust the flow rate of the granules 32 from storage container 30 into storage and heating chamber 44.

[0042] Storage and heating chamber 44 is configured to heat the granules contained therein 56. The heating device 41 comprises a heater, eg an induction heater, a gas furnace rail 52 as shown in Figure 1 , or may utilise alternative apparatus for transferring heat energy via gas-flame, radiation, conduction or otherwise, into storage and heating chamber 44, to heat the granules 56 that are contained within the chamber 44. The heating device 41 is preferably configured to be able to heat the contents of chamber 44 up to about 800°C. In preferred embodiments, the contents of the chamber 44 may be heated to an average temperature of about 100°C to about 700°C.

[0043] The heating device 41 may comprise a start button 48 to start the heating of granules 56 located in storage and heating chamber 44. Alternatively, the heating device may be controlled remotely, eg from the driver's cab of a vehicle fitted with the apparatus 10. In embodiments where a gas fired heating furnace is used, starting the heating device may involve igniting the gas provided through gas furnace rail 52, which in turn begins to heat the storage and heating chamber 44 and transfer heat into the granules 56 that are contained within the storage and heating chamber 44.

[0044] The apparatus 10 also comprises a drive motor 58 connected to the storage and heating chamber 44 to rotate the chamber 44 on bearing mounts 46 and 47. In one embodiment as illustrated in Figure 2, the chamber 44 is a tank such as a cylindrical tank, positioned with its cylindrical axis approximately horizontal relative to the ground. The chamber 44 may be rotated about its longitudinal/cylindrical/symmetrical axis through a controllable drive system of gears 60 and 62 which are connected via chain 61 to motor 58 for the agitation and mixing of the granules 56 in either direction (ie clockwise or anticlockwise about the longitudinal/cylindrical/symmetrical axis). That is, as the chamber 44 is rotated, the granules are driven substantially horizontally while being tossed and tumbled due to the internal fins 54 as described in more detail below. Speed and/or direction of rotation of the drive motor 58, and thereby the heating chamber 44, may be remotely controlled, eg from the driver's cab of a vehicle fitted with the apparatus 10. In one example, the drive motor 58 is a 12V 30W high torque reversible gear reduced DC motor, that is capable of rotating a heating chamber of about 0.5m long (cylindrical/longitudinal axis) and about 0.4m in diameter. The drive motor 58 may be controlled, for example, by a pulse width modulation (PWM) motor speed controller.

[0045] Figure 3 illustrates the apparatus 10 installed on a standard road-marking vehicle according to one embodiment. As will be appreciated, the compact size of the apparatus 10 according to preferred embodiments allows the apparatus to be easily installed or retrofitted onto standard road-marking vehicles. The apparatus 10 may easily be scaled up for large or continuous works such as longitudinal highway markings.

[0046] Storage and heating chamber 44 may contain internal fins 54 that are mounted (eg welded) to the inside of the walls of the chamber 44. The fins 54 may be configured in a corkscrew pattern, with the axis of the corkscrew aligned with the symmetrical/longitudinal axis of the heating chamber 44 and the corkscrew tapering toward an exit port 45, defined at the centre of the bearing mount 46 of chamber 44. This example embodiment is shown more clearly in Figure 2. It will be appreciated that alternative configurations of internal fins 54 may be provided, for example, separate discrete fins instead of a continuous corkscrew auger, or inwardly extending paddles fixed to the wall of the chamber 44, etc. Further, alternative embodiments may comprise a rotatable auger within a stationary chamber 44.

[0047] Accordingly, by rotating the heating chamber 44 and/or the internal fins 54 about the longitudinal axis in one direction, the solid granules 56 may be evenly and thoroughly heated, mixed, agitated, rotated and driven across the blades of the internal fins 54 and across the length of the chamber 44. By rotating the heating chamber 44 in the opposite direction, the granules 56 can be driven in the opposite direction to exit via the exit port

45. The rotation of the chamber 44 about a substantially horizontal axis as illustrated in the embodiment of Figures 1 and 2, and the resulting horizontally rotating movement of the granules 56, ensures that the granules may be retained within the chamber until sufficiently heated and agitated (ie, the granules are not driven through and out of the chamber solely by gravity). Further, the illustrated embodiment also allows the direction of the rotation of the chamber 44 to be changed abruptly or mid-cycle, to further jolt the granules and improve mixing and heating of the granules 56.

[0048] In other embodiments, the heating chamber may be installed in a vertical/gravity- fed configuration on stabilising mounts 76, for example as illustrated in Figure 9. The chamber 44 may comprise rotating fin(s), such as a rotating auger 54 within the stationary chamber 44. As granules are fed into the top of the tank via inlet 170, the granules fall downwards by gravity through interstitial space 73, and are then scooped/driven upwards on the rotating flight of augur 54 (or alternative internal mixing fins), thereby tumbling, mixing and rolling the granules over each other. The augur 54 may comprise flight lip 184 to contain the granules as they are being raised on the flight. The chamber 44 may be heated by gas furnace rails 52 positioned adjacent or around the chamber, eg adjacent the interstitial space 73, to heat the granules as they are driven and rotated through the chamber. Outflow of granules through exit port 45 may be controlled or controllable to ensure sufficient heating and tumbling of the granules prior to dispensing via the port 45. In some embodiments, the chamber 44 may additionally be controllably pressurised (eg via pressure inlet coupling 180 and pressure release valve 182) to assist with transport and/or distribution of the beads. The inlet 170 and outlet port 45 may be sealable in order to pressurise the chamber.

[0049] The apparatus 10 may further comprise one or more temperature sensors 96 located within a shroud 40 of the heating device 41 , or within the chamber 44, as illustrated in Figure 8. For example, the temperature sensor 96 may comprise a K-type thermocouple probe mounted via sensor mount 98 at an inlet or outlet port of the heating chamber, and extending into the heating chamber to measure the temperature of its contents. In one embodiment as illustrated in Figure 8, the temperature sensor 98 may be mounted adjacent a top of the inlet and within the inner cavity of the corkscrew auger such that incoming granules do not contact the temperature sensor and the sensor does not rotate with the heating chamber 44.

[0050] The apparatus may further comprise control electronics (not shown) for controlling operation of the drive motor 58 and/or gas furnace rail 52 to control the temperature of the granules within the chamber 44. Figure 7 is a functional specification illustrating control functionality according to one embodiment. For example, speed of rotation of the chamber 44, direction of rotation of the chamber 44, and/or temperature of the heating device 41

(eg by controlling gas furnace rail 52) may be controlled based on temperature measurements such as the average temperature of the granules within the chamber 44. In some embodiments, the apparatus 10 may comprise one or more displays and/or one or more alarms (eg a visual or audio alarm) to indicate to the user if the temperature of the beads within the heating device 41 is above or below predetermined temperature thresholds. In some embodiments, the temperature measurements may be input to a logic controller to automatically adjust one or more of the above operation parameters of the apparatus 10 accordingly.

[0051 ] The shroud 40 of the heating device 41 protects the heating chamber 44, and insulates the chamber 44 to maintain consistent heat during operation. The shroud 40 also acts as safety insulation to prevent burning if heating device 41 is accidentally touched. Shroud 40 may comprise vents 42 that may be adjustable to allow for the controlled release of heated air for adjusting the temperature of the heating chamber 44 and/or to facilitate cooling-down of the device. Vents 42 may also be connected to a flue (not shown) to direct heated air away from within shroud 40. Shroud 40 may further comprise vents 49 that may be adjustable to allow for air intake into shroud 40 where a gas-flame or similar is used as the heat source for heating chamber 44.

[0052] The heating device 41 also comprises a device or means for dispensing the heated reflective beads 56 onto the painted surface 22 (before the paint has dried or cured) which results in a road marking 24 comprising a heated layer of reflective beads embedded within the painted surface. In the illustrated embodiments, the dispensing device comprises a third feed pipe 64 and dispensing nozzle 72, which are arranged in fluid communication with the storage and heating chamber 44. The third feed pipe 64 may be insulated and/or heated to substantially maintain the temperature of the heated beads 56 until the beads are dispensed from the nozzle 72 onto the painted surface. In some embodiments, the third feed pipe 64 is flexible or adjustable in position, to allow for the feed pipe to be aligned with the paint nozzle 18.

[0053] In some embodiments, a control device 66 is provided to adjust the rate of flow of granules through the feed pipe 64 and dispensing nozzle 72. The control device 66 may comprise a pressurised air connection or calibrated gravity feed device or other appropriate flow control apparatus in order to ensure that the deposition rate of the heated granules may be controlled, for example in response to environmental conditions or the varying speed of a vehicle fitted with the apparatus 10 relative to the road surface 20. This may help to ensure adequate heated bead 74 coverage over the painted surface 22, without excessive deposition that can lead to wastage of surplus granules. In some embodiments, the dispensing nozzle 72 may comprise a chute with adjustable flanges to vary the spread and angle of bead dispersion from the nozzle 72.

[0054] In some embodiments, the apparatus 10 may comprise a fourth storage container 80 in which surplus granules 88 that are reclaimed from completed road markings 24 can be recovered and stored. Storage container 80 may contain an internal sorting mesh 82 which captures non-granule debris such as rocks and moves them into a fifth storage container 84 via exit connection 86. Reclaimed granules 88 are able to pass through mesh 82 and pass into reclaimed storage container 80. This embodiment affords several advantages over prior art marker painting apparatuses and methods, such as the immediate reclamation of surplus granules.

[0055] In some embodiments, a suction head 92 is connected to storage container 80 via a fourth feed pipe 90 to retrieve surplus granules. Suction head 92 may be configured to travel above the road surface 20 (so as not to damage undried road markings 24) via wheels 94 that may be driven adjacent the road marking 24.

[0056] In use, paint 14 is sprayed onto the surface 20 via the first nozzle 18 while the apparatus 10 is conveyed along the surface 20 to form the initial road marking 22. In the meantime, granules 56 are heated, mixed and tumbled within heating chamber 44. Heated granules 74 are then dispensed onto uncured paint 22 via the dispensing nozzle 72. Importantly, the heated reflective beads 74 are applied to the paint 14 promptly after the paint 14 has come into contact with the surface 20 and while the paint 14 is still wet or uncured. The paint 14 then dries or cures with the reflective beads 74 embedded within the paint to form road marking 24. Surplus reflective beads that are extraneous to the road marking may then be suctioned through pipe 90 and stored within storage container 80, resulting in road marking 26. In some embodiments, the method steps may be repeated in order to obtain a sufficiently thick marking for high-build applications. For example, an initial layer of paint 14 may be deposited, the heated granules 74 applied, a second layer of paint 14 may be applied on top of the initial layer and a second layer of heated granules 74 applied. It will be appreciated that the present apparatus and methods provide improvements in efficiency for such high-build applications.

[0057] Heating the granules 56 affords several significant advantages over prior art marker painting apparatuses and methods. Firstly, when the heated beads 74 come into contact with the undried or uncured paint 22 on the surface 20, the beads 74 transfer their heat energy to the paint 22, thereby raising the temperature of the paint 22 and substantially reducing the required drying/curing time of the paint. [0058] Further, heating the granules 56 also ensures that any moisture surrounding or coating the granules is evaporated before the heated granules 56 come into contact with the paint 14. Removing any moisture from the granules also prevents clogging of the granules that can commonly occur when wet or moist granules pass through the feed pipe 64 and exit port 45. Tumbling, mixing and agitating the granules within the chamber 44 and causing the granules to roll over each other may also remove other unnecessary surface coatings or contaminants coating the granules. This ensures that the granules adhere to the paint 14 in the best possible manner and are more uniformly distributed over the surface 20. This, in turn, improves the reflectivity and durability of the road marking.

[0059] Further, the process of heating and agitating the granules 56 within the heating chamber 44 has been shown to improve the reflectivity of the road marking 24. Without subscribing to any particular theory, it is believed that heating the glass beads may evaporate the moisture trapped within the beads (due to the hydrophilic property of glass), thereby increasing the reflectivity of the glass beads by reducing or eliminating the refractive effects of water. Tumbling and rolling the beads over each other within the rotating chamber 44 may also help to polish the glass beads, by removing microcracks and surface imperfections, and improving sphericity and thereby reflectivity of the beads. The rotating kinetic energy of the chamber 44 is transferred to the beads, causing them to roll and fold over each other as they are driven across the length of the chamber, increasing the polishing effect. Further, it has been found that the process of heating and/or tumbling the glass beads may also improve the clarity of the beads, such that when applied to a white paint strip, for example, the effect of the bead layer on the whiteness of the paint is minimal or negligible, compared to conventional unheated bead applications.

[0060] The process of heating and agitating the glass beads has further been found to improve the reflectivity of the beads even when applied cold to paint. That is, embodiments of the present invention provide for a manufacturing process of glass beads that comprises a post-processing treatment of heating and tumbling the glass beads. The post-processing step may be applied using a heating and mixing apparatus similar to chamber 44 to produce glass beads having higher clarity, resulting in higher reflectivity of road markings. In a similar manner, glass beads reclaimed from the completed road markings, via eg suction apparatus 92 as described above, after having undergone the heating and agitating process, may exhibit improved clarity and may be advantageously re-used.

[0061 ] In some embodiments, the granules 56 are heated so that they are at a temperature of about 80°C to about 500°C when they come into contact with uncured paint

22 on the surface 20. Preferably, the granules 56 are not heated to or above their softening point. Preferably, the granules 56 are not heated to or above safety thresholds of the paint, such as the auto-ignition and decomposition temperature levels.

[0062] In some embodiments, the granules 56 are heated so that they are at a temperature of about 150°C to about 300°C when they come into contact with uncured paint 22 on the surface 20.

[0063] Selecting a suitable heating temperature for the granules is important to ensure improved trafficability while also maintaining proper embedment of the granules. Conventionally, for optimal bead reflectivity and bead retainment, approximately 60% of the spherical glass bead should be embedded into the paint layer. If the granules are too hot, for example, too much of the bead may be exposed, resulting in poor embedment upon contact with the paint layer. Accordingly, suitable heating temperature of the granules 56 is generally dependant on operating conditions, such as ambient temperature, humidity and air movement, as well as the type of paint used. For example, under colder conditions the bead temperature may be increased, eg for cold night time applications below 5°C, the beads may be suitably heated to about 260°C, whilst in hotter conditions it has been found that a reduced bead temperature may be more suitable, eg about 100°C in 40°C conditions.

[0064] To ensure that the granules 56 are heated to the correct temperature, or within the correct temperature range, the apparatus 10 may comprise a temperature sensor 70 at or near the exit point of the heated granules from the apparatus 10, and control electronics (not shown) that operate in conjunction with the heating device 41 and/or drive motor 58 to control the temperature of the granules deposited from the apparatus 10. For example, the sensed temperature may be fed back to the controller to automatically adjust the temperature within the heating chamber 44, the speed of rotation of the chamber 44, and/or direction of rotation of the chamber 44.

[0065] In some embodiments, the outflow rate of the granules through the exit port of the chamber 44 may be controllable, eg by controlling the size of the exit port. Embodiments of the present apparatus and method provide a bead application rate of about 200 grams per square meter (g/m ² ) to about 600 g/m ² , depending on the size of the granules, preferably around 400 g/m ² , which is the typical industry standard rate for high volume applications such as on highways and main roads.

[0066] It will be appreciated that, in addition to or as an alternative to glass beads, the granules 32 may comprise crushed glass particles or other particulate material. Whilst the granules are preferably retro-reflective, the granules may comprise a non-reflective particulate material, such as sand.

[0067] The present apparatus and method may be used to paint a wide variety of surface markings, including longitudinal and transverse markings, on roads, pathways, car parks, airports and other substrates and thoroughfares.

[0068] It has been found that the present apparatus and method substantially reduces the required paint drying and curing time and improves the reflective quality and durability of the completed road marking. This increases productivity and reduces the risk of vehicle run-throughs and other defacing that can commonly occur to newly created road markings. In particular, it has been found that the present apparatus and method substantially improves trafficability in cold or humid climates where expensive prior art chemical-based paint accelerating additives have a negligible benefit only. Accordingly, the present apparatus and method may eliminate or reduce the need for chemical accelerating additives in paint products.

[0069] The faster trafficable time provided by embodiments of the present invention resists wheel tracking and water washouts, protecting the integrity of the road marking and the distribution of glass beads that are critical to night time retro-reflectivity. Bead applications using the present method have shown excellent durability over both asphalt and concrete road surfaces in a variety of climates. Even greater durability and longer life can be achieved with high-build applications based on 'layering' of heated beads and paint, as discussed above.

[0070] It has been found that the present apparatus and method may be used with thermoplastic marks, with the heated and tumbled beads acting to activate thermoplastic adhesion to the road surface. This method advantageously reduces discoloration of the thermoplastic which is a common consequence of using a gas-flame to melt and activate the thermoplastic in conventional systems.

[0071 ] The present apparatus and method can be used with a higher temperature range onto hot-applied thermoplastics to both increase the embedment of the granules and also to improve the traction of the surface of the finished product.

[0072] Conventional road marking methods commonly leave behind a surplus of unused glass beads on the roadway on either side of the road marking after the glass beads have been applied to paint 20. These surplus glass beads are typically left on the roadway to disperse, over time, into the environment. Glass beads may contain a component of lead and surplus beads are typically undesirably moved by passing traffic off the road surface and into the environment. Embodiments of the present method and apparatus have the ability to reduce the wastage and negative environmental effects of existing road marking processes, by reclaiming the surplus glass beads from the road surface. Through the present process of applying beads that have been sufficiently heated onto the uncured road marking paint, and the resultant improvement in the trafficability and bead embedment of the road marking that this process yields, it is possible to reclaim surplus beads by suction applied almost immediately after the mark has been applied. The suction does not dislodge the beads that have already been applied to the freshly applied road marking as they are now embedded within, and sufficiently adhered to, paint 14 due to the heating and application process of the invention. Accordingly, the reclaiming apparatus 80-94 may be installed on the same vehicle and operated at the same time as the road marking apparatus, enabling operators to quickly and conveniently clean up as they go.

Example 1

[0073] In one in-situ trial illustrated in Figure 3, the apparatus 10 was mounted on a standard road marking vehicle. Conventional paint guns on the vehicle were used to dispense paint onto the road.

[0074] A control mark and a test mark were applied adjacent each other on the road surface. For the control, a paint layer of approximately 500 μηι thick (wet film thickness) was applied and retro-reflective B-Type (Drop On) glass beads at ambient temperature (approximately 12°C) were deposited onto a 12°C road surface. The application rate was approximately 350 - 400 g/m ² . The test mark was applied with the same conditions (ie 350 - 400 g/m ² of B-Type beads onto 500 μηι wet film thickness paint layer on 12°C road surface), but with the heated beads according to the present method.

[0075] Specifically, the granules 56 were heated from ambient temperature to about 220°C in five or fewer rotations of the heating chamber 44, which took about 8 seconds or less. The speed of rotation of the heating chamber 44 was 26 RPM. The temperature of the heated granules when deposited on the road was about 180°C.

[0076] The trafficability of the control mark was about 42 minutes. In contrast, the heated bead test mark was trafficable within 2 minutes. That is, it was found that the test mark was substantially immediately trafficable when a vehicle was driven across the test mark within 2 minutes after the application, and no paint was picked up by the vehicle's tyres (ie no run-through). [0077] Further, a calibrated reflectometer (Zehntner GmbH) measurement of the test mark by a qualified Main Roads representative indicated approximately 50% average increase in the expected reflectance of the mark across the length and width of the mark.

Example 2

[0078] An indoor trial of the present method was performed with the apparatus 10 mounted on a standard road marking vehicle. A silicon mat was painted using conventional paint guns on the vehicle, to deposit a layer of about 500 μηι thick (wet film thickness) for each test mark. The ambient temperature indoors was between 28 to 30°C. Results of the test are shown in Figures 5 and 6.

[0079] The control mark (Test BH1 .0) was obtained from the in-situ trial described in Example 1 above, ie retro-reflective B-Type (Drop On) glass beads at approximately 12°C were deposited onto the paint. The trafficability was measured at about 42 minutes.

[0080] Test mark BH2.0 was also obtained from the in-situ trial described in Example 1 above and was completed immediately after the control mark (Test BH1 .0) was applied. Retro-reflective B-Type glass beads at approximately 200°C were deposited onto the paint. The trafficability was measured at 1 minute and thirty five seconds, clearly demonstrating substantial time savings compared to the cold glass beads.

[0081 ] Various other test marks (Tests BH3.0 to BH7.0) were applied using B-Type glass beads at different bead temperatures, as detailed in the table of Figure 5. It was found that heating the beads up to between approximately 180°C (Test BH4.0) and 220°C (Test BH5.0) provided the best trade-off in trafficability time and effective embedment of beads. The tests BH4.0 and BH5.0 resulted in trafficability of 45 seconds and 36 seconds respectively, clearly demonstrating substantial time savings compared to the control mark.

Example 3

[0082] The photograph of Figure 4 shows a visual comparison of reflectivity of a test mark applied using the present apparatus 10 (right), an industry standard mark on a test plate (left) and a reflective raised pavement marker (middle). The industry standard mark was applied using the standard rate of 350 g/sqm of glass beads and illustrates typical reflectivity of approximately 320 millicandela. The retro-reflective raised pavement marker has a typical reflectivity of approximately 1000 millicandela. From visual comparison, it is clear that the reflectivity of the test mark applied using the apparatus and method of the present invention is substantially comparable to the high reflectance level of the retro- reflective raised pavement marker.

[0083] Embodiments of the present invention provide methods and apparatus that are useful for economically and effectively applying road markings.

[0084] For the purpose of this specification, the word "comprising" means "including but not limited to", and the word "comprises" has a corresponding meaning.

[0085] The above embodiments have been described by way of example only and modifications are possible within the scope of the claims that follow.