ROAD MARKING METHOD - THE APPLICATION OF RIB PADS

Abstract: The invention concerns a machine for putting down plastic strips or pads (40) in spaced array along a demarcation line of a road or motorway surface to provide a "rumble" strip for traffic. The machine also has a presser (34) for pressing the pads to the road surface to achieve good adhesion in that the pads are either applied to a newly laid white line whilst it is still soft, a previously laid white line on the road surface which has either been softened by heat or to which adhesive or soft plastics bonding material has been applied.

Description: Road Marking Method - The Application of Rib Pads This invention relates to a method of applying road markings to motorways, trunk roads and the like. Specifically the invention is concerned with the application of rib pads to a road surface, such that the rib pads protrude above the road surface and are applied at spaced intervals along a road. The application of the said pads is performed by mechanical means such that the application can be accurately performed. The purpose of such rib pads is, in combination, to cause a vibratory effect on a vehicle upon the vehicle wheels passing over the said rib pads. The rib pads protrude above the road surface and as such, in general terms, shall be evident above road surface water. At present rib pads are applied to the road surface by means of a complicated and expensive vehicle which is required to lay down fluent and molten material to form a base strip on the surface as the vehicle travels along the surface with the rib pad itself being formed of a similar material to that of the base strip. During the application, the strip pads are formed by a mechanical shutter mechanism which allows a blob of material to form on the strip. In this form the equipment for the application of the rib comprises a hopper for the material and a heating means. The molten material is applied to the road surface in the form of a base strip and a series of blobs. As a result of the formation of the ribs from the same material as the base strip and the simultaneous application of the base strip and the ribs, the machinery so described has the disadvantage of requiring the rib application to be performed at the same time as the base strip is laid. This has the effect of slowing down the application process when the time allowed for the process is frequently limited by traffic flow constraints ie in the form of limitation of traffic congestion. Furthermore, if failure occurs in the operation of any part of the application machine, then it is difficult to continue the road marking operation until a replacement machine is available. In addition the simultaneous application of base strip and ribs requires that the consistency of the material forming the strip and ribs be the same. This is wasteful as the composition of the ribs is normally required to be harder wearing than that of the base strip as it is the rib pads with which vehicle wheels are most in contact. Furthermore the vibration effect of a rumble strip is best achieved when the sides of the ribs are vertical. The present method is unable to achieve this as the hot material slumps causing the ribs to lose their definition. The present invention aims in one aspect at the application of rib pads to a surface to form a rumble strip or demarcation strip wherein the pads are applied to a base strip in a molten state or to a road surface independently of a base strip and by an integrated reciprocal or rotary application method comprising placing and securing operations for the application of each rib pad. A further aim is to provide for the manufacture of rib pads such that they need not be manufactured from the same material as is the base strip and said rib pads need not be manufactured simultaneously with the base strip. According to the present invention there is provided a rib pad formed of thermoplastic material wherein said rib pad can be applied to a road surface or base line to form a demarcation line or rumble strip. In accordance with one aspect of the invention there is provided a means for forming a rumble strip on a road surface wherein said rumble strip comprises a base line of paint or thermoplastic and a series of raised protrusions, each of said protrusions being provided by the application of a rib pad to the base line. In one embodiment, the base line will be previously applied and will be heated to a molten state to allow the rib pad to be applied thereto. Typically upon application the rib pad will be secured by pressing the rib pad into the molten surface by a third operation. Preferably the operation so described will be performed from one rib pad laying unit. The said rib pads will be stored on the rib pad laying road unit by means of a magazine mounted thereon such that the rib pad to be laid is removed from the bottom thereof. In a further embodiment the pads will be preformed on the rib pad laying road unit from, in one embodiment, roll mounted on the said rib pad laying road unit wherein the rib pads to be laid are punched out therefrom prior to being laid by the placing mechanism. The three operations of heating, placing and securing of the rib pads so described shall be performed by the rib pad laying road unit in sequence such that the direction and speed of movement of the unit shall be continuous. In the invention the rib pad laying road unit will be capable of applying the rib pads at regular spaced intervals and said spaced intervals will be adjustable to suit the required spacing intervals. The rib pads shall be transported by the rib pad laying road unit which will be capable of applying pads of varying dimensions to the required surface. The machine for the application of the pads will heat the surface to which the rib pads are to be applied by applying heat produced from gas burners mounted in close proximity to the said surface to a state of fluidity sufficient to accept therein the rib pads. The securing operation of the pad laying unit will be performed by either a wheel which upon passing over the pad serves to press the pad into position. In another embodiment, particularly suited for when the pads may lie at an angle after placing, the wheel will be replaced by a heating head which will heat the pad sufficiently that it will, in effect, form as one with the molten base surface. The invention provides an application method wherein the rib pads are applied from a powered road unit capable of variable speed and which can be steered to follow a set path in which the pads are to be laid. The storage of rib pads, gas canisters for the burners and associated equipment can be transported on the application unit. As an alternative to the powered road unit the rib pad will be laid by the means of a manually controlled rib pad laying unit wherein the said unit is manually controlled by an operator and the laying operations are controlled by means of mechanical actuation, as the said unit is pushed along. In another aspect of the invention the rib pads will be applied to a base strip when said strip is still in a molten state and said rib pads will be secured therein prior to the molten base strip hardening. Typically said rib pads will be applied immediately after the said base strip laying operation. Preferably said molten base strip will be applied from the rib pad laying road unit. In a third embodiment of the invention the rib pads will be applied to a road surface to form a demarcation line wherein said rib pad will be applied to a blob of material in a molten state applied to the road surface prior to the application of the rib pad; Preferably said rib pad will be applied to the blob of material and said rib pads and blobs of material will be oversprayed or painted with a largely continuous line of material to form a rumble strip. Typically the application of said largely continuous line will be followed by the spraying thereon of reflective beads which, when part of the line, render the line reflective. Typically said blob of material will be molten plastic. In a fourth embodiment, said rib pad will have a layer of adhesive applied to the bottom thereof such that when said rib pad is applied it will adhere to the road surface or base line to which it is applied. Preferably said rib pad after application will be oversprayed with paint to form a rumble strip. Typically said adhesive will be applied to the rib pad prior to mounting in the rib pad laying unit and said rib pads will be held on backing material and laid on to the road surface. In a further aspect of the invention said rib pads will be manufactured from a plastics material remote from the laying of the rib pads. In the invention there is provided a rumble strip rib pad of thermoplastics material having a ligh reflective top surface provided by light reflective spheres embedded in the plastics. Preferably there will be incorporated into the said manufacturing process the capability to apply reflective beads to the rib pads such that the reflective quality of the rib pads is enhanced thereby. Preferably the said beads will be applied to the rib pads by the means of a spray of the said beads. The pads may be further reflectorised by the attachment of reflective devices to the rib pads and preferably along the longitudinal edges of same. Typically said rib pads will have reflective strips attached to the vertical edges of said strips. Thermoplastic material of varied colours may be used in the manufacture of the said rib pads to suit the statutory road marking colours required. Preferably the rib pad dimensions will be such that they can be laid on the base strip by the Rib Pad Laying Unit so described. Preferably the rib pads as manufactured will be of 4.5cm width and either 20cm, 15cm or 10cm in length. In one embodiment the rib pads will be manufactured by the extrusion of lengths of thermoplastic material, the said lengths being subsequently cut to form the said rib pads of required dimension. As an alternative to cutting the said lengths of thermoplastic material it will be possible to control the flow of the extrusion of the thermoplastic material such that the material can be extruded in controlled lengths. This embodiment will provide means whereby a shutter mechanism will control the length of the rib pad to be produced, by controlling the length of each extruded part to match. Preferably the extruded material shall be laid in a molten state onto polypropylene film to protect the conveying system from damage. The extruded material shall be cooled as quickly as possible from the molten form by means of a blast freezer or by the treating of said material with water. In a further aspect of the invention there is shown the method of using rib pads with a soft bonding layer applied to the underside of the rib pads to compensate for irregularities in the road surface to which rib pads are to be applied. There may be provided in a further aspect of the invention the use of rib pads with a soft bonding layer applied to the road surface to compensate for irregularities in the road surface. Typically the bonding layer for use on the underside of the rib pads will be provided by the softening, with heat for example, of the underside of the pads. In another aspect of the invention the bonding on the underside of the rib pads shall be provided by the application of extra bonding to the underside of said rib pads. In a further aspect there shall be provided the application of base material to the road surfce prior to application of rib pads to fill in any pot holes or irregularities which may exist in the road surface. Furthermore in another aspect the application of rib pads to the road surface can be followed by the laying thereon of a line and thirdly the spraying thereon of beads. Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, wherein.- Figure 1 is a plan view of one embodiment of a rib pad laying road unit; Figure 2 is a rear end elevation of the road unit shown in Figure 1; Figure 3 shows a perspective view of the rib pad depositing assembly and the rib pad roller; Figure 4 is a plan of the central column of the rib pad depositing assembly shown in Figure 3; Figure 5 shows another embodiment of a rib pad depositing assembly; Figure 6 shows a rib pad laying unit of a further embodiment; Figure 7 is a plan view of one embodiment of the rib pad manufcturing plant; and Figure 8 is a elevation of another embodiment of the rib pad manufacturing plant. With reference to the drawings and in the first instance to Figures 1 and 2 there is shown a road unit 2 from which the rib pad laying operation is performed. The unit 2 is a four vehicle having four wheels 4 and comprises a driver seating area 6, a fuel tank 8, gas canisters storage area 10, a tool box 12, work table 14, work platform 16 and a rib pad storage area 18. On one 22 of the edges 20 and 22 running longitudinally of the road unit 2 there is mounted the rib pad laying equipment 24. The rib pad laying equipment 24 comprises a burner section 26 which consists of a series of gas burners 28. A depositing assembly 32 is mounted behind the burner section 26 in relation to the direction of travel 30 of the road unit 2 and is followed by a presser roller 34 for applied rib pads. To increase the visibility and safety of the road unit 2 the rear of the road unit 2 is equipped with flasher lights 36 and has the capability of having hazard signs 38 fitted thereon. The depositing assembly 32 is shown in greater detail in Figures 3 and 4 and comprises a central column 42 in which the rib pads 40 are contained. Column 42 formed of two U- sectioned bars 44 and 46. To accomodate different sized rib pads 40 spacers 48 (as shown in Fig 4) can be placed inside the column along with the said pads when loading the central column 42. At the bottom 50 of the central column 42 a slot 52 therein allows one rib pad 40 at a time to be pushed by a mechanism 54 in the direction 56 onto a spring flap 58 held normally in a horizontal position by spring 60. In the order to lay the rib pads 40 the unit 2 is driven at a speed, approximately 1 mile per hour, and on a path such that the road laying equipment 24 is positioned above that line on road on which the rib pads 40 are to be laid. With the road unit 2 driven in the direction 30 shown, the burner section 26 supplied by gas from tanks 10 serves to melt the road surface immediately below the burners so that the surface melts which allows the rib pad 40 subsequently to be pressed therein. The rib pads are deposited by depositing assembly 32 Each rib pad is deposited by means of the pad having been pushed by mechanism 54 to reach a position 62 on the spring flap 58 and the holding force of the spring 60 is overcome by the returning action of the mechanism 54 which is connected to the said flap.This causes the flap to lower into the position shown by the broken lines 64 and allows the rib pad 40 to slide into position on the molten surface. The frequency of depositing the rib pads 40 on the surface is dependant on the frequency of reciprocation of the mechanism 54. The reciprocatory movement is controlled by a linkage geared to the engine of the road unit 2. The spacing of the rib pads 40 along the road is dependent upon the speed of the unit 2 and the frequency of reciprocation of the mechanism 54. When in postion on the surface, each rib pad 40 is pressed into the soft, heated road surface by the pad roller 34. Roller 34 passes over the said pad as the road unit 2 continues in direction 30. Instead of a pressing roller 34, a pressing spider wheel may be used comprising radial arms each with a pressing bar on its extremity. The spider wheel rotates in synchranism with the laying of the pads so that each presser bar in turn comes down onto and presses a previously applied pad. The pad laying process of heating, placing and pressing is repeatedly and continuously performed as the said road unit continues in the direction 30, with the depositing assembly 32 being refilled with rib pads 40 when required by an operative on the road unit 2. Instead of the burners 28, column 32 and the presser being on a dedicated machine it may be connected to a conventional vehicle such as a lorry. In another embodiment as shown in Fig 5 the depositing assembly 32 consists of the mechanism 54 and the central column 42 as described previously. The spring flap 58 and spring 60 are omitted. The rib pads 40 are held in the central column 42 which as before has a slot 52 formed therein. The central column 32 is mounted at such an angle that the rib pads 40 are held in position so that the bottom rib pad 40 will not leave the central column 52 until pushed by mechanism 54 and when it is so pushed, it falls freely and predictably to the ground. In a further embodiment,the rib pad roller 34 may be removed and replaced by a heater head. In this embodiment once the rib pad 40 has been placed in position by the depositing assembly 32, it is heated by the heater head such that the rib pad melts sufficiently to allow a bond to be formed with the heated surface upon which it is laid. This prevents the pad from cracking due to the pad roller 34 passing over and especially when applied to uneven surfaces. Instead of the pads being displaced from the magazine 32 by a reciprocating mechanism, they may be fed to a feed wheel having peripheral notches into which the pads are placed one by one, and as the process proceeds the wheel is rotated and carries the pads round the wheel one by one and presents them to the road surface. This can be used in any embodiment. In further embodiments (not shown) the rib pad laying unit will be provided with means whereby a base strip can be laid onto the road surface prior to the rib pad application process. Typically this will involve the removal of the burner section 26 and replacement with a base line point application means. Figure 6 illustrates a rib pad laying unit wherein the burner section 26 and the roller 34 have been removed. The roller 34 has been replaced by a bead spraying mechanism 66 thereby illustrating the adaptability of the rib pad laying unit. Referring now to Figure 7 and 8 there is provided a manufacturing line 68 for the manufacture of rib pads 40 to be applied to a base strip on a road surface. To produce the said rib pads 40 there is provided at one end of the manufacturing line 68, a hopper 70 in which the raw thermoplastic material 72 is placed. Adjacent the hopper 70 there are boilers 74 and leading therefrom is an extruder 76 of a worm screw variety 78. Directly below the extruder 76 there is a first conveyor system 80 and laid thereon is a polypropylene film 82. Adjacent the extruder 76 there is mounted a pressurised bead pot 84 which is connected to a bead spray arm 86 mounted above the said conveyor. At the end of the first conveyor system 80 there is mounted a vertical cutter 88. A second conveyor system 90 leads from the said cutter at the end of which there may be provided a collecting hopper (not shown) . The manufacturing procedure commences with the transferral of the said thermoplastic raw material 72 from the hopper 70 into the boilers 74 wherein the material is transformed by heating into a molten state. Exits 92 from the boilers 74 release the molten material into the extruder 76 which feeds the molten material onto the polypropylene film 82 on the first conveyor system 80. The material is extruded in a thin strip of width such that the required length of rib pad will be so formed. The material in molten state is conveyed in direction 94 where it passes under the bead spray arm 86 from which the beads are impact sprayed such that they bond with the said molten material. As the material is conveyed it is quickly cooled and as it passes to the cutter 88 it is an almost solid state. The cutter 88 reciprocally cuts the material to form rib pads 96 as shown. The said rib pads are further cooled on the second conveyor system, are removed from the said polypropylene film and are collected prior to being shipped for the subsequent application to base strips, or road surfaces. There may also be provided as part of the manufacturing line at least one blast freezer or water cooling system to increase the rate of cooling of the extruded material such that the material properties are as desired for the remaining spraying and cutting operations. It may also be desired that the application of the reflective beads may be applied after the rib pads have been cut to shape such that the edges of the said rib pads may also be coated with the said beads. The pads can be further reflectorised by reflective devices such as for example reflective tape or plastic reflectors, being placed, stuck or embedded into the longitudinal edges of the pads. The said reflective devices may be protected by a layer of hard wearing plastic film. Coloured thermoplastic material may be used for or with the pad. Thus the pad may be formed wholly of the coloured thermoplastic material or may have a strip of the said material bonded thereto. The coloured edges can thus be placed facing towards the motorist for maximum reflectivity and warning. Shown in Figure 8 is an alternative pad making plant wherein the cutter 88 is omitted and there is provided a shutter mechanism 98 fitted to the extruder 76. The shutter mechanism can be controlled to produce extruded lengths to match required width or length of rib pads thereby alleviating the need for the cutter 88. The three operations of heating, placing and securing may be performed by the means of a manually controlled and propelled rib pad laying road unit. Integral to this unit in one embodiment will be a means for heating the base strip and a manually controlled lever application mechanism whereby the rib pad can be laid on the road surface as the road unit is propelled along the road surface. The effect of the said three operations are similar to that provided by the powered road unit. The manually controlled road unit may be especially suited to operations which require increased manouevrability or involve only small stretches of rib pad laying. The mechanism for dispensing the pads can be attached to existing screed, spray and extruding machinery so that pads can be laid directly on to newly applied base lines whilst the material is still molten, thus alleviating the need for heating up of the base line. This unit has the advantage of providing, in one integral unit, a method of laying the said rib pads wherein the operations of heating, laying and pressing are part of one linked system with a comparatively high degree of automation which ensures that the rib pads 40 are laid in a systematic and efficient manner without the requirement for a simultaneously laid base strip. The rib pad laying road unit allows rib pads 40 of varying sizes to be laid independently of the laying of any base strip as is required by existing methods. This will allow the said rib pad laying to be performed more quickly and traffic congestion will be minimised and thus greater flexibility in the planning of a rib pad laying process is provided. The safety of the operatives is greatly increased by this rib pad laying unit as it allows the operatives to operate from the vehicle itself which is equipped with hazard signs and affords the said operators a degree of protection against collision with any other vehicle. Furthermore, the ability to lay the rib pads to the road surface and then overspray allows the rib pads to be located as an integral part of a rumble strip whilst maintaining the flexibility of the rib pad laying mechanism. The ability to provide preformed, reflectorised rib pads, manufactured remote from the point of application to the road surface or base line provides a pad which is adaptable and flexible in use to form a demarcation line or rumble strip. The apparatus and method according to the invention in its various embodiments can be used for the creation of rumble strips in various circumstances as follows. Firstly, when the line of the road along which the pads are to be provided has no existing white line and none is to be provided before the pads are applied, the pads may be applied by heating and softening the road surface as described followed by application of the pads to he heated surface. The pads will mainly be of the rigid type described, but could be portions of molten material which subsequently hardens. Alternatively the pads may stick to the road surface with adhesive, such as pressure sensitive adhesive on the underside of the pads. After the pads have been applied, a strip of molten white lining material may be applied over the pads so that a rumble strip continuous white line is formed. Where the road surface along the line where the rumble strip has to be formed already has a white line, this may be softened by heat and the pads applied to the softened material before it re-hardens. Again, the pads may be rigid components or may be applied as molten portions. Another possibility is that the pads (rigid) can be stuck to the white line using adhesive. Where there is no white line, but one is to be provided, this may be applied as described herein by applying the molten material to the road surface to form the strip, followed by the application of the pads (rigid) whilst the strip is still warm and soft. Again it is possible to apply a further strip of white lining over the applied pads. In all cases where rigid pads are used, they are preferably pressed downwards onto the receiving surface after application. Any feature of any rib pad laying apparatus described herein can where appropriate be used in combination with any other feature of that apparatus or any other such apparatus described herein.

Claims: CLAIMS 1. A rib pad formed of thermoplastic material wherein said rib pad can be applied to a road surface or base line to form a demarcation line or rumble strip. 2. A means for forming a rumble strip on a road surface wherein said rumble strip comprises a base line of paint or thermoplastic and a series of raised protrusions, each of said protrusions provided by the application of a rib pad to the base line. 3. A means for forming a rumble strip according to Claim 2 wherein the base line will be previously applied and will be heated to a molten state to allow the rib pad to be applied thereto. 4. A method for producing a rumble strip according to Claim 2 wherein said rib pads are applied to a base strip when base strip is in a molten state and said rib pads secured therein prior to base strip hardening. 5. A method for producing a rumble strip according to Claims 2 and 4 wherein said rib pads are applied to the abuse strip immediately after the base strip has been laid. 6. A method of producing a demarcation line wherein rib pads of thermoplastic material are applied to a road surface at spaced intervals. 7. A method of producing a demarcation line according to Claim 6 wherein said rib pads are adhered to the road surface by means of adhesive layer on the bottom of said rib pads. 8. A method of producing a demarcation line according to Claim 6 wherein a blob of molten plastics material is applied to the road surface and the rib pad applied to said blob of material. 9. A demarcation line as in Claims 6-8 wherein said line is oversprayed or painted to form a rumble strip. 10. A rib pad as in Claim 1 wherein said rib pad is provided with a reflective coating of ballatini beads. 11. A rib pad as in Claim 1 wherein said rib pad has provided along the vertical edges thereof reflective strips of material. 12. A rib pad as in Claim 1 wherein said rib pad can be produced in colours according to transport and road regulations. 13. Apparatus for laying a rumble strip or demarcation line wherein said apparatus comprises a means for placing rib pads at spaced intervals onto a base strip or road surface and a means for pressing said rib pad into position. 14. Apparatus for laying a rumble strip as in Claim 13 wherein said apparatus includes a burner unit to render a previously applied base strip or road surface into a molten state prior to application of the rib pads. 15. Apparatus for laying a rumble strip according to Claim 13 wherein said apparatus includes a base strip application means whereby the rumble strip base strip is applied prior to application of rib pads. 16. Apparatus for laying a rumble strip according to Claim 13 wherein said apparatus includes means for spraying of reflective beads on to said rumble strip to provide reflective effect. 17. Apparatus for laying a rumble strip according to Claim 13 wherein said rib pads are held in a magazine such that one rib pad is placed at a time from each magazine. 18. Apparatus for laying a rumble strip according to Claim 13 and 17 wherein there is provided a plurality of said magazines. 19. Apparatus for laying a demarcation line according to Claim 13 wherein said apparatus includes a means for applying blobs of molten plastics material to the road surface, and the placing and pressing of rib pads therein. 20. Apparatus for laying a demarcation line according to Claim 13 wherein said apparatus includes a means for applying an adhesive layer to the bottom surface of said rib pads. 21. Apparatus for laying a rumble strip or demarcation line according to any of Claims 13 to 20 wherein said apparatus is a road laying unit, said unit is powered and the rumble strip or demarcation line forming apparatus are part of an integrated reciprocal application process linked to the speed of movement of the vehicle and the distance required between each rib pad. 22. Apparatus for laying a rumble strip or demarcation line according to any of Claims 13 to 20 wherein said means for placing comprises a feed wheel having peripheral pockets to receive the pads and deliver same, by rotation of the wheel, to the road suface. 23. Apparatus as in Claim 21 or 22 wherein the rib pad laying unit is capable of being driven by an operator and the application of said rumble strip or demarcation line controlled thereby. 24. Apparatus for the operations described in Claims 13 to 23 wherein said apparatus is manually powered and said operations of placing and pressing of the rib pads are controlled by mechanical actuation. 25. Apparatus for the manufacture of rib pads for use in forming rumble strips or demarcation lines wherein said rib pads are formed from thermoplastics material remote from the point of application of the rib pads to the road surface or base strip. 26. Apparatus according to any of Claims 13 to 24 wherein said presser means comprises a spider wheel having radial arms with pressing means at the end thereof.

Inventors: PACEY BARRY DAVID, PACEY, BARRY, DAVID
Applicants: PACEY BARRY DAVID, PACEY, BARRY, DAVID
Application year: 1992
Main classification: E01F9
IPC codes: E01C23, E01F9