CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. provisional patent application 63/171,495, filed April 6, 2021. This application is hereby incorporated by reference.

FIELD

[0002] This application relates in general to the field of road marking products. In particular, it relates to reflective stripe markings for visibility in dark conditions.

BACKGROUND

[0003] Retroreflective traffic stripes, also known as, or in the form of, road markers or delineators are illuminated at night by the headlights of vehicles and return light back to a driver’s eyes to delineate lanes of traffic. Traffic stripes are applied to surfaces of roadways at the lateral edge of and between lanes and perpendicular to the lanes at crosswalks and intersections. These products are typically glass bead filled paints or extruded polymer. The spherical beads at the surface receive light and retroreflect the light back to the direction of the headlights with some divergence so it can be seen by the driver. The current glass bead and ceramic bead products have low reflectivity and visibility especially during wet night conditions. In addition, these products deteriorate over time and become even less reflective.

[0004] Other alternatives include raised reflective pavement markers made primarily of polymeric materials and employing cube corner prisms for retroreflection. These are more reflective than tape or paint but, are subject to intense wear since they protrude from the surface. [0005] The average age of drivers is increasing. This also implies that there are more drivers with poorer eyesight and slower reaction time on the road. In addition, there is an increasing demand for autonomous vehicles, which require brighter and more reliable signals. This has caused the US Department of Transportation and safety advocates in other countries to seek brighter, longer lifetime road marking alternatives.

SUMMARY

[0006] In an embodiment disclosed herein is a novel retroreflective traffic stripe comprising a micro cube-comer retroreflective film (See Fig. 14), also called prismatic film that is attached directly to a structure formed in the road surface. The structure may be in the form of a series of protrusions, the series running laterally to the road lane, i.e., at the edge of the lanes, and running perpendicular to the length of the road lane. (The length of the road lane being its longest dimension including a direction in which traffic flows.) In contrast to paint or glass bead-filled compositions, this returns more light to oncoming vehicles and drivers. The product disclosed herein is designed to provide greater visibility over longer time periods compared to current products. Current products have significantly lower visibility which deteriorates quickly in two to three years.

[0007] In an embodiment, a novel method of pre-grooving the pavement in such a way that it positions the prismatic film for optimum visibility is presented. The groove is also intended to protect the prismatic film from substantial direct tire impact and plow blade contact. Earlier attempts to position and protect glass-bead or ceramic-bead composites in grooves required discrete patterns, such as the 3M 380 Tape that placed the glass-bead or ceramic-bead composites at the protruding feature edges for maximum retroreflectivity. Even so, the total retroreflective area is low and the glass-bead or ceramic-bead composites are inherently less efficient than prismatic reflective film.

[0008] A recent patent, U.S. 10,794,021, disclosed a method to extract and redirect light from prismatic film to the driver using another layer of light turning features. The features that extract and turn the light toward the driver are very small (0.36cm wide) (0.072 cm above the base surface) and may be easily damaged by tires and clogged by debris on the roadway.

[0009] In an embodiment disclosed herein, the corner cube retroreflective substrate is utilized without the disadvantage of exposed TIR (total internal reflection) light turning surfaces which are susceptible to damage.

[0010] In addition, an embodiment disclosed herein significantly reduces the material cost compared to glass-bead or ceramic-bead tape products as well as the light-turning comer cube product since layers required by the prior art that support the optic features are eliminated.

[0011] As disclosed herein, glass-bead or ceramic -bead tape products as well as light-turning comer cube tape products can be recessed below the road surface (see Fig. 1) to minimize tire impact and damage from plow blades. In an embodiment, the product disclosed herein can be installed by grooving the surface of the road and positioning the cube corner prismatic film in the groove and below the road surface at an angle facing diagonally up and facing traffic. This provides better protection for improved durability because concrete and asphalt have higher abrasion resistance than any of the alternative tape or paint products. In another embodiment discussed below, a flat groove running laterally on a top face of the road surface and along the length of the road has disposed within it a strip of polymeric material with protrusions including retroreflective film configured to face traffic in a same or similar geometry to the grooves covered with retroreflective film. Reflective mini-marker protrusions as disclosed herein can be utilized and applied to pavement in a rolled system or placed by a pick and place machine, or even manually onto a polymer-based layer.

[0012] Corner cube retroreflective films are an order of magnitude brighter than glass-bead or ceramic -bead tape products as well as light turning concepts with reduced area. Most retroreflective film substrates used for traffic signs are made of polymethyl methacrylate (PMMA), which has good outdoor stability and light transmission, but does not have good abrasion or impact resistance. In an embodiment disclosed herein aliphatic thermoplastic urethane (TPU) is utilized for the film because it has good UV stability, high light transmission and abrasion resistance, as well as high impact resistance.

[0013] In an embodiment, a road lane marking system running laterally to the road lane on pavement includes a series of protrusions running laterally to the road lane, the protrusions being spaced apart. The protrusions have an angled traffic-facing surface that is configured to reflect light to oncoming traffic in the road lane. The protrusions have a flat top part and a reflective material is coupled to the angled traffic-facing surface. The reflective material has a height of greater than 1 mm. In an embodiment, the cube comer angles will be different from that of road signs to account for their angled arrangement.

[0014] In an embodiment, a method for making a road lane marking system includes removing road surface material from a lane marking area to form a series of protrusions with traffic-facing angled surfaces; applying an adhesive to at least the traffic facing angled surface; and adhering a reflective material to the traffic-facing angled surface.

[0015] In another embodiment, a rolled road lane marking system includes a series of mini markers with reflective material bonded to an angled surface and regularly spaced on a release film, the release film being adhered to a top flat portion of the mini-markers. The longest dimension of the mini-markers is approximately perpendicular to the longest dimension of the release film.

BRIEF DESCRIPTION OF THE DRAWINGS [0016] Figs 1-3 are perspective views of road marking stripes and rumble strips. [0017] Figs. 4A-4D are cross-sectional views of alternative rumble strips.

[0018] Fig. 5 is a perspective view of an embodiment of a road marking system.

[0019] Fig. 6 is a cross-sectional view of an embodiment of a road marking system.

[0020] Fig. 7 is an overhead view of an embodiment of a road marking system.

[0021] Figs 8 is a cross-sectional view of an embodiment of a road marking system.

[0022] Fig. 9 is a cross-sectional view of an embodiment of a road marking system.

[0023] Fig. 10 is a cross-sectional view of an embodiment of a reflective mini-marker.

[0024] Fig. 11 is a perspective view of an embodiment of a rolled road marking system.

[0025] Fig. 12 is a perspective view of an embodiment of a road marking system.

DETAILED DESCRIPTION

[0026] The embodiments disclosed herein provide a method of recessing a product into a roadway surface and a new product that can be recessed into the roadway surface. A new roadway surface with a reflective marking product is therefore provided.

[0027] Methods to groove pavement to recess lane marking paint are available as shown in the depiction of a road groove 10 in Fig. 1. The road groove 10 has a base surface 11, which in this case is fairly smooth, that is recessed from the road top surface 12. Other methods and equipment are available to provide milled coarse rumble strips as shown in Fig. 2, or fine rumble strips as shown in Fig. 3 and Figs. 4A-4D.

[0028] This equipment includes micro-milling machines that are self-propelled machines that contain one or more rotating drums with diamond or carbide tip teeth. As the drums turn, the teeth come into contact with and remove asphalt or concrete pavement. Milling machines can be used to grind a depression or groove where pavement markings are designated. This allows the pavement marking paint or tape to be recessed and protected from traffic wear and snowplows scraping off the pavement markings. Typically, the recessed grooves are about 5 mm (0.200 inches) deep but that can be changed as required depending on the thickness of road marking to be protected. More effort and resources (diamond and carbide tipped teeth) are required for deeper grooves.

[0029] In an embodiment, protrusions can be formed by polymer or some other material and fitted with reflective material and bonded to the flat groove in the pavement with intermittent spacing. In another embodiment, mini-markers with the reflective material applied can be manufactured as discreet functional protrusions and attached to a carrier film at the proper spacing. In another embodiment, grooves are formed in the pavement perpendicularly to the length of the road (direction of traffic), thereby forming a protrusion with the remaining uncut pavement, and reflective material can be bonded to a traffic facing side of the protrusion. This embodiment, eliminates some materials and material costs, but is more labor intensive.

[0030] One alternative to the concept of applying the microprismatic reflective film directly to a milled pavement structure, is to have similar ridged structures pre-formed in a flexible polymer that is strong, abrasion resistant and has high impact strength such as high-impact, abrasion resistant polyurethane. One example of this is 3M 380 ceramic bead tape product. Polyurethane resin can be cast onto a mold and cured, e.g. in a continuous operation to produce rolls of the design selected for particular applications. The protrusions for attaching the reflective film can be molded into the strip of material at the intervals mentioned above and can have the same geometry as disclosed above for the pavement protrusions. The rolls of cured polyurethane can be white, yellow or any other color that may be required. The microprismatic reflective film then attached to the positioning features would be of the same color.

[0031] The microprismatic reflective film could be attached using a pressure sensitive adhesive or by any of the other methods described previously and also over-coated with clear polyurethane or any other suitable protective coating. This product could be formed in rolls similar to the way glass bead or ceramic bead products are sold and attached to the pavement using a pressure sensitive adhesive similar to those being used for other reflective tape products. In this regard, the preformed polymer with attached film would then be inserted into a full length groove running parallel to the road direction machined into the pavement surface.

[0032] Figs. 5 and 6 show an example of protrusions with reflective material for highway markings. Four protrusions 25 are shown in Figs. 5 and 6. Each protrusion 25 has a base surface 29 that may be the bottom surface of a groove cut in the road.

[0033] The flat-bottomed base surfaces 29 space out the protrusions so they are visible from a distance, i.e. not completely blocked by the protrusion in front of them. See Fig. 5 and 6, base surface 29. The protrusions may be spaced apart, e.g., by 250 mm to 30 mm, such as 40 to 125 mm, or 50 to 100 mm. In an embodiment, the protrusions are spaced closely enough to prevent a standard sized, e.g. 17 inch tire from touching the bottom of the groove. [0034] These protrusions 25 have an upward angled traffic-facing surface (See Figs. 5 and 6, angled surface 27) that faces the direction of oncoming traffic in the lane it is associated with and is configured to reflect light back to oncoming traffic in the road lane. This angle (See Fig. 8 angle 109) can be 0 to 60 degrees from vertical (straight up and down), such as, for example 30 to 55 degrees, or 35 to 50 degrees. (See Fig. 8.) The angled surface 27 may have some curvature, such as, at the bottom or top of the protrusion. In the case of a curved surface, the angle would be measured by the line that is tangent to the inflection point.

[0035] The protrusions have a flat (i.e., flat as in level with the road surface) top portion 26 that protects the reflector surface on the traffic-facing surface and distributes the weight of a tire that might roll over it. See Fig. 6, flat top portion 26. The flat top portion may be, for example, 5 mm to 50 mm in length in the direction of traffic flow, such as, for example, 8 mm to 30 mm, or about 10 mm.

[0036] The protrusions also have a sloping back surface (See Fig. 5 and 6 back surface 30), which may be angled down at about a 35 to 85 degree slope, such as 45 to 75 degrees, or 50 to 70 degrees. (See Fig. 8, angle 107.)

[0037] Referring to FIG. 6, in an embodiment, if the protrusion 25 positions the retroreflective film that is 10 mm wide at the flat top 26, and has a 3 mm high face 27, then the distance between the top of each reflective area will be 125 mm for vehicles that are 30 meters away. These are example dimensions and can be varied, e.g., by plus or minus 100%, 50% or 25%. For example, the face 27 (i.e. the face of the reflective material) may have a height of at least 1 mm, such as 1.5 mm to 24 mm, 2.25 mm to 6 mm, or 2.5 mm to 4.5 mm. Height being measured by the height of the retroreflective film face 27 top to bottom, not a distance from the base surface. [0038] Fig. 7 shows an overhead view of the protrusions 125 with some measurements. In an embodiment, a recessed road groove 110 is shown with protrusions 125 spaced evenly along it. Alternatively, in accordance with the other embodiment, item 131 here, could also be a flat polymeric ribbon 131, with protrusions 125 spaced evenly along it. The groove width 141 can be 151.8 mm or about 6 inches; and the protrusion width 143 can be 101 mm or about 6 inches.

A section length 145 is also shown, which includes 4 protrusions 125 and base surfaces 129 in between and at the ends. The base surfaces 129 at the ends are half the length of a base surface 129 shown between protrusions 125. This section length can be 500 mm or about 19.7 inches. These are example dimensions and can be varied, e.g., by plus or minus 100%, 50% or 25%. [0039] Fig. 8 is a zoomed-in cross-section of a single protrusion 125 for showing certain angles as discussed above. This figure shows a single reflective face, and would be used for vehicles viewing the markers from one direction such as a divided roadway, where all the lanes on one side have traffic movement in one direction and all the lanes on the other side have traffic movement in the other direction. This embodiment, can be used for an edge strip on either side of an outside lane, regardless of whether the highway is divided or not.

[0040] In an embodiment for a roadway with lanes with traffic moving in opposing directions, the center line separating the opposing direction lanes would have similar protrusions but be double-sided, with a reflector and the associated angle of incline for the protrusion on each side. In this embodiment, drivers from both opposing lanes viewing the center line from their direction of travel will see a reflector.

[0041] In accordance with embodiments disclosed herein, milling techniques can be modified to provide a series of small, parallel ribs with geometric profiles. By milling grooves in the pavement with a geometric profile as shown and described herein it will provide the positioning surfaces for the microprismatic reflective film or tape. In certain embodiments disclosed herein, a flat base surface is milled with protrusions running perpendicularly to the direction of traffic just below the road surface, e.g., in a recessed groove 5 mm below the road surface. This protects the reflective material from plow blades and other road-going hazards.

[0042] Methods for making a microprismatic delineator on a road surface by milling grooves or otherwise removing pavement are disclosed. This can be made by known road work machinery, in some cases with modifications, and utilized in a manner to at least create a diagonal traffic facing surface (i.e., the traffic facing surface is sloping from a bottom of the groove up and away in the direction of traffic) that is lower than the plane of the road. Typically, the groove will be outside the edge of a traffic lane, though it could be used for markers inside the lane boundary. [0043] In an embodiment, grooves could be formed in a generally sinusoidal formation as shown in Figs. 4A-4E. These figures show a profile cross-sectional view of rumble strip alternative geometries. The y-axis represents the depth of the rumble strips with zero being the top of the pavement. Fig. 4A shows a traditional truncated sine-wave configuration for rumble strips.

Figs 4B to 4D show non-truncated sinusoidal alternatives: Fig. 4B shows an alternative sinusoidal 24” wavelength; Fig. 4C shows an alternative sinusoidal 18” wavelength; and Fig. 4D shows an alternative sinusoidal 12” wavelength. In an embodiment, the reflective material would be placed on the traffic-facing side of a groove. The reflective material could be bonded only to select grooves, such as by skipping every 1 to 10 grooves, e.g., 2 to 8, or 3 to 6 grooves. Generally, the spacing of reflective material and protrusion dimensions disclosed herein could be the same in this embodiment.

[0044] Instead of protrusions placed on a flat groove or a ribbon laid down in groove, in an embodiment, a road surface can be milled with the same or similar profile protrusions in the pavement as could be manufactured with polymeric materials and bonded to flat groove. In this embodiment, a line may be painted over the protrusions and grooves that is white or yellow and then microprismatic reflective film can be bonded to the traffic-facing surfaces of the protrusion formed by milled grooves.

[0045] The machinery and technique could be modified to match the geometry shown in Figs. 5 and 6. The modification of the groove geometry primarily is to add a gap separating the raised portions, such that the diagonal traffic-facing portions are more visible from a car at a distance down the road. In an embodiment, sinusoidal configurations as in Figs. 4A-D can be utilized, in another embodiment they are excluded. In an embodiment, the grooves still function as a rumble strip to create noise alerting the driver to an out-of-lane condition.

[0046] In an embodiment, the area for the marking stripe (typically running in a stripe lateral to (beside) the road lane) is coated with a durable paint stripe material, such as a polyurea. The road surface should be free of particles before applying the polyurea or any adhesive. This can be accomplished with air flow sufficient to blow away particulates. The polyurea stripe can also be colored with pigment, e.g., white or yellow as required by local laws. This material can also be function as an adhesive before it cures. Before curing completely, a corner-cube retroreflective film is placed onto the diagonal traffic-facing surface of the groove. The retroreflective film can have an adhesive backing as well. After curing the retroreflector will be durably bonded to the surface. If the marking stripe is not used, an adhesive on the back of the retroreflective film can be used alone.

[0047] In one example, the microprismatic retroreflective film, which may comprise aliphatic thermoplastic urethane can be attached to the milled ridge protrusion formed in the pavement by coating a white polyurea stripe over the milled ridges that will remain tacky for several minutes. The tacky surface will allow the sections of microprismatic film to adhere and permanently bond after the polyurea cures. [0048] The cure time of the polyurea can be adjusted depending on the installation time required for the microprismatic film. The underlying colored polyurea stripe could be applied 101 mm or 153 mm (4 inches or 6 inches) wide as typical lane markings, or values in between, and will provide an additional white background for daytime visibility. Polyurea paint has been extensively used for road marking paints and found to be very durable and abrasion resistant. [0049] In either case of the embodiment of Figs. 5-7 or the grooved pavement alternative, the prismatic film will retroreflect light to the drivers’ eyes with higher intensity than glass bead or ceramic bead products and is better protected from tire abrasion by the flat top surface in the pavement. In one example, the traffic positioning surfaces for the microprismatic reflective film are located at the bottom of the 5 mm (0.200 inches) milled groove typically used to protect other road markings such as paint or tape from traffic wear and snowplows. In other embodiments the reflective film is placed above the bottom of the groove, but not extending above the groove. [0050] In an embodiment, the below grade reflective marker has the maximum possible retroreflectivity per the allowable surface area but is protected to a greater degree from tire impact and plow blades. The traffic stripe disclosed herein (comprising the protrusions or mini markers) may have a coefficient of Retroreflected Luminance [mcd/m ² /lux] of at least 1,000, such as 1,100 to 5,000, or 1,200 to 2,000, at an entrance angle of 88.76° and an observation angle of 1.05°. This 88.76° angle is measured between the incident light and the normal to a stripe, that is, the normal to the road. In contrast to the angled devices and system disclosed herein, no smooth flat retroreflective sheeting can cope with 88.76° entrance angle. If the backslope angle of the devices disclosed herein is 45°, the vertical entrance angle component to the reflective sheeting on the protrusions is 43.76° in the CEN geometry, and the horizontal component is 0°. [0051] In embodiments, a different type of reflector can be used for the retroreflective film. For example, the retroreflective material disclosed in U.S. 4,895,428 with cube-comer prisms. This prior patent is incorporated herein by reference.

[0052] In an embodiment, the microprismatic retroreflective film will be bonded to a protective backing film to provide an air gap behind the prisms so they can function by total internal reflection (TIR). The protective backing film will hermetically seal the reflective film to protect it from dirt and moisture. The sealing method may be any of those commonly used to manufacture microprismatic reflective sheeting for traffic signs, such as by ultrasonic bonding of the two layers as shown in U.S. 5,930,041 incorporated herein by reference. In an embodiment, the backing material is polyurethane and top layer is also polyurethane, and can be the same polyurethane. In an alternative construction, the film is bonded by forming cell walls using a water-based acrylic urethane with the prisms being protected by fumed hydrophobic silica as described in U.S. 4,672,089, incorporated herein by reference.

[0053] Reflective embossed cube-corner thin film on the order of 0.006 inches (150-microns), can be sandwiched between polymeric (e.g., TPU) layers. The film can also be from 0.001 inch to 0.5 inch in thickness, such as, for example, 0.01 to 0.1 inches in thickness. The film may have on the order of 22,000 cube-comer elements per square inch (3,400 per square cm), or, for example, 5,500 to 44,000 elements per square inch, or 12,000 to 33,000 elements per square inch. The backing film can also be an acrylic copolymer on the order of 0.002 inch (0.05 mm) thick, such as 0.0005 to 0.004 inches, or 0.001 to 0.003 inches. In an embodiment, an ultrasonic bond or a water base acrylic urethane holds the layers together, and enclosed cells provide an air gap for the internal retroreflectivity. These can be hermetically sealed with air or hydrophobic silica.

[0054] The geometric retroreflective elements, or precision microstmctures, are defined by some or all of the following characteristics: precise depths; flat surfaces with precise angular orientation; fine surface smoothness; sharp angular features with a very small radius of curvature; and precise dimensions of the elements and/or precise separation of the elements, within the plane of the film. The retroreflective elements may be cube-corner elements comprising three mutually perpendicular faces which serve to receive incident light and retroreflect the light through 180° approximately parallel to its incident path and back to its source. The cube-corner element may have a structure of three mutually perpendicular faces without regard to the size or shape of each face or the optical axis of the element so provided. [0055] As used in the present application, "precision microstmctured" material generally refers to a resinous polymeric material having a precise geometric pattern of very small elements or shapes, such as 0.5 mm to 100 nm, 0.1 mm to 1 micrometer, or 0.05 to 10 micrometers in at least one dimension, such as the largest diameter, height, or width, and in which the precision of the formation contributes to the functionality of the product. In an embodiment, the precision of the panel is a function of both the precise geometry of the product, the capability of the forming tool, and the process and apparatus to conserve the geometric integrity from tool to article formed in the panel (on one or both sides thereof), and may include one or more characteristics mentioned in U.S. 4,895,428 or U.S. 6,015,214, incorporated herein by reference. In an embodiment, the precision shapes in this application may be even smaller than disclosed in those earlier patents, e.g. by 100% or less, 50% or less, or 10% or less, as determined by longest dimension. Smaller features may provide advantages in having more rows of retroreflective features.

[0056] In certain embodiments of precision microprismatic film, discrete elements and/or arrays of elements may be defined as formed recessed regions, or formed raised regions, or combinations of recessed and raised regions, relative to the unformed regions of the panel. In other embodiments, all or portions of the precision microstmctured panel may be continuously formed with patterns of varying depths comprising elements with some of the characteristics described above. Typically, the discrete elements or arrays of elements are arranged in a repetitive pattern; but the product may also have non-repetitive arrays of precision microstmctured shapes. Exemplary types of precision microstmctured panels, and their characteristics of precision, include retroreflective materials for road reflectors or signage (but the angles of internal reflection should be different than typical road signs). Cube-comer type reflectors, to retain their functionality of reflecting light back generally to its source, have three reflective faces of the cube maintained flat and at some chosen minutes difference from 90° relative to each other. The chosen deviations from 90 degrees determines the observation angularity of the retroreflector. Human factor studies recommend visibility distances which can be accommodated by dihedral angle variations among the prisms, in accordance with U.S. 7,370,981 incorporated herein by reference.

[0057] Prior patents, U.S. 4,895,428 or U.S. 6,015,214, incorporated herein by reference, also disclose details on geometrical shapes and patterns that may be used.

[0058] Roadsign retroflective sheetings are intended for incident light arriving at modest angles off normal. They generally have their retroreflective elements symmetrically arranged, so for each element that is good at retroreflecting light arriving with a particular incidence, there is another nearby element that is good at retroreflecting light arriving with the opposite incidence, relative to the normal. Classical, triangular cube-comer sign sheeting achieves such symmetry in its mling method. Newer, rectangular and hexagonal cube corner sign sheetings achieve the symmetry by piecewise assemblies. For the system and devices disclosed herein, however, while the retroreflective film retroreflects incident light arriving in a modest range of horizontal (left- to-right) entrance angles, the vertical component entrance angles can be very large, while their range is tiny, no more than about 2 deg. Vertical and horizontal components of the entrance angle are determined as follows. A normal line (i.e., a line that is perpendicular to the tangent line at the point of tangency) to the reflective sheeting is erected at the point where incident light strikes a center point of the reflective sheeting. The angle formed between the incident light and the normal is called the "entrance angle". Viewing the entrance angle from above, or equivalently projecting it onto a horizontal plane is the "horizontal component of the entrance angle". Viewing the entrance angle from the roadside, or equivalently projecting it onto a vertical plane aligned with the road direction is the "vertical component of the entrance angle". When a vehicle is very far (mathematically considering it infinitely far) from the reflective sheeting on the protrusions, the vertical component of the sheeting entrance angle is exactly equal to the backslope of the face. As the vehicle gets closer, the vertical component must shrink simply because the headlamp has some height above the road. If a typical car has its headlight 0.65 m above the road, then at a quite far distance of 200 m, the vertical component of the entrance angle has shrunk by 0.23°, and at a quite close distance of 20 m, the vertical component of the entrance angle shrinks by an additional 2.12°. This tiny range is independent of the backslope.

[0059] For road sign reflective sheetings, entrance angle demands are in a range from 0° to some maximum, e.g. 30°. In contrast, for tilted road markers laying on the road surface as disclosed herein, the entrance angle demand does not include 0°. There is a horizontal component range from 0° to some maximum, like 20°, and there is a vertical component range from backslope to backslope of less 2°. In an embodiment, this range is to one side of normal, and the reflective sheeting functions asymmetrically, e.g., it performs with the 43.76° entrance angle with orientation angle 0° and not with orientation angle 180°.

[0060] Moreover, in an embodiment, the vertical incidences are all situated to one side of the normal, toward the road, without symmetry. The maximum vertical entrance angle can be, for example, 30 deg. 45 deg, or 60 deg, depending directly on the backtilt angle of the traffic facing surface. The choice of the backtilt angle may be governed by the mechanics of wear due to traffic, and this depends on the mentioned material and dimensional variations used in the devices and systems.

[0061] To produce a highly effective system and device, depending on the backtilt angle of the protrusions on the traffic-facing side, cube comer retroreflective films should be employed that are highly reflective to the corresponding vertical entrance angle. For example, the cube corner geometries described in U.S. 4,895,428, incorporated herein by reference, can be utilized for vertical entrance angles greater than about 15 degrees. The similar cube corners described in U.S. 6,015,214, incorporated herein by reference, offer additional advantages for the horizontal entrance angle range, if desired. If the backtilt angle is less than about 20 degrees the cube comer geometries appropriate to roadsign sheetings can be considered for the systems and devices disclosed herein.

[0062] In an embodiment, a segment of a microprismatic type reflective thermoplastic web can be used in forming the laminate of the retroreflective film. The rear surface of a portion of flexible retroreflective film fashioned from transparent thermoplastic material in web form which has formed thereon, such as by embossing, may be a retroreflective and repeating pattern of microprismatic reflector elements characterized by cube faces. The film can be formed from a thermoplastic urethane, which prior to embossing, had parallel front and back surfaces and was initially on the order of about 0.15 mm (0.006 inches) thick. One such material is known as CLC60D-V Estane TPU sold by Lubrizol Advanced Materials, Inc. This material is particularly for the prism layer in the tape product embodiment, whereas polyurethane is used for the main material of the tape product, i.e., the non-reflective part consisting of the protrusions and flat layer therebetween.

[0063] The microprismatic pattern formed on sheeting is formed in an optically precise finely detailed pattern as known in the art. In particular, see Fig. 15 from U.S. 4,895,428 and accompanying text, and also Fig. 16 from U.S. 6,015,214 and accompanying text, each of these incorporated by reference herein.

[0064] Retroreflectivity is achieved by microprismatic type reflector elements primarily through the principle of total internal reflection. In order to facilitate this, it is known in the art to provide an air gap between the prism apices and any substrate to which the film is attached, such as, for example, as shown in U.S. 5,930,041, which is incorporated herein by reference.

[0065] Fig. 9 shows the layer structure of an embodiment of the road marking system as a cross- section running laterally and parallel to the road. The pavement 205 is the bottom layer and forms a protrusion 225. On top of the pavement 205, lateral to the road surface on which traffic travels is a polymer-based marking stripe 210, e.g., polyurea. This is typically colored, e.g., white or yellow and runs a length of the road over several protrusions without interruption. The tape or adhesive layer 215 is to couple the top reflective layer 220 to the polymer-based marking stripe 210. Alternatively, the tape or adhesive layer 215 can be omitted, if the polymer-based material is sufficient to adhere the reflector to the pavement 205 alone. This may be accomplished by applying the reflective material 220 prior to full curing of the polymer-based material.

[0066] If further protection of the microprismatic reflective film is desired, an additional layer of clear polyurea or other polymeric material can be applied to minimize damage to the microprismatic reflective film.

[0067] As alternatives to polyurea there are several other suitable coatings that can be used to bond or protect the microprismatic reflective film such as epoxy or water base paints from various sources. The clear protective coating can be any clear liquid that does not dissolve or interfere with the function of the reflective film that provides adhesion to the milled ridge protrusion and protects the surface of the reflective film from chipping or scratches.

[0068] As another example, the microprismatic retroreflective film can be attached to the milled ridge protrusion that was formed in the pavement by a pressure sensitive adhesive such as those used for other reflective tape products such as the 3M 380 road stripe tape. Yet another example of providing a retroreflective surface is to array the reflective film into small pieces or strips and then apply them to the milled positioning surfaces by any of the methods described previously. [0069] Another example is to ultrasonically bond the reflective film to a protective backing film similar to what is done during the manufacture of reflective sheeting for traffic signs but in this case use the sonic-sealing process to also cut out the hermetically sealed discrete pieces that can be applied to the milled positioning surfaces by the methods described previously. Ultrasonic bonding of the layers can be done as shown in U.S. 5,930,041, incorporated herein by reference. At least one additional advantage of this construction is providing a variety of discrete pieces that localize damage. In an embodiment, corner cubes geometry is varied to cause the reflected light to be distributed over larger observation angles. Certain variations in geometry are disclosed in U.S. 4,895,428 or U.S. 6,015,214, incorporated herein by reference respectively. [0070] Another example is to ultrasonically bond two layers of reflective film so that both sides are reflective and use the ultrasonic-sealing process to cut out small hermetically sealed discrete pieces that look like confetti having reflectivity on both sides. The hermetically sealed discrete pieces can typically range from 2 mm square to 10 mm square, such as 3 to 8 mm square, or 4 to 7 mm square, and can be various shapes as desired such as round or hexagonal as well as square. The embodiment can be dropped on to polyurea while it is still wet as a means to provide a microprismatic surface over the face of the protrusions. This method manufacture would approach the ease of application of glass beads over wet paint. As an additional protective measure, a clear protective coating can be applied over the reflective confetti. This simplified method will be comparably as easy to apply as glass beads over paint but with advantages of microprism film such as higher reflectivity, the ability to adjust the reflectivity to provide the best signal for the driver, a clear protective coating, and the ability to maintain reflectivity even under water.

[0071] Regarding the position of the microprismatic reflective film on the protrusion face, the desired location the ASTM E1710 specification for road markings is based on the "CEN 30 meter geometry", which is founded on a simplified car 30 meters away from the road stripe. By using a 125 mm pitch between the top areas of the microprismatic reflective film, cars closer than 30 meters will shine a small portion of their light in front of the retroreflectors, and not be reflected. However, if the pitch is less than 125 mm, cars closer than 30 meters would see more reflectivity. If dirt accumulation near the bottom of the retroreflector is a concern, then a pitch less than 125 mm, whereby the 30 meter car (and ASTM E1710 testing) illuminates just an upper part of each retroreflector, is advantageous. If wear near the top of the retroreflector is a concern, then a pitch of less than 125 mm (e.g. 115 mm to 50 mm, or 100 to 75 mm), whereby the 30 meter car (and ASTM E1710 testing) illuminates just an upper portion of each retroreflector, is a possible option.

[0072] Additionally, to distribute the retroreflected light, custom microprismatic designs can be arrayed into each 3mm wide reflective face to achieve different degrees of divergence angle performance. The arrayed designs can be stripes, squares or any arrangement that provides the range of reflectivity required at specific incident angles or divergence angles. These dimensions and angles can be varied by, e.g., plus or minus 100%, such as, e.g. plus or minus 50% or 25%. [0073] By varying the angles of divergence, this embodiment would allow improved visibility for high seated vehicles such as trucks, since the ASTM standard is based on relatively low- seated cars. In an embodiment, there are at least two different angles of divergence, e.g., one in accordance with ASTM E1710 and one configured for semi-trucks. In an embodiment, three or more, e.g., 5 to 20, or 8 to 15 different angles of reflectivity are provided on the microprismatic strips to better reflect light at a range of automobile seat/viewing heights. Alternatively, two or more different reflective strips could be used and alternated, one for cars and one for semi- trucks. The ASTM E1710 test for the U.S. is based on a 1.24 degree observation angle. In other embodiments, the divergence angle could be configured to reflect light at 0.2°, 0.5°, 1.0°, and 2.0° observation angles. In an embodiment, the varied angles of divergence could be 0.1° to 2.0°, or 0.1° to 0.20°, or 0.2° to 5°.

[0074] Fig. 10 shows another embodiment of a protrusion with reflective markings, in this case, referred to herein as a mini-marker 325. A method of providing this mini-marker 325 is to extrude, mold, or otherwise produce and shape a thermoplastic substrate used for road marking. This can be done while it is hot (e.g., above its glass transition temperature) and in a shape disclosed in Fig. 10 or as otherwise disclosed herein. Then reflective material 320, such as a film strip can be applied to the mini-marker followed by a protective overcoat (not shown). The reflective material 320 can be applied in a recess 363 in the mini-marker 325 as shown, or not in a recess, but on the upward-angled surface of the mini-marker 325. The reflective material 320 can be on both sides, as shown, or just one, i.e., at least one side facing forward traffic flow. In an embodiment, the reflective material 320 comprises ultra-sonicahy sealed cells with air gaps. The reflective material 320 may have a single row of rectangular cells. Each cell in the single row may be hermetically sealed, such that ah cells are sealed from water incursion.

[0075] The mini-marker 325 is attached to a road groove 310 with a polymer-based layer 308, which can also include pigment and act as a paint as disclosed herein. The mini-marker 325 also includes an undercut 365 below the upward-angled surface on one or both sides which aids in anchoring the mini-markers 325. The top of the polymer-based layer 308 rests above the undercut and below the reflective material 320. A bottom edge 367 is jagged or otherwise non smooth. This promotes bonding to the road groove 310 surface.

[0076] In an embodiment, an uncured polymer-based layer 308 is laid down into the road groove 310, and the mini-marker 325 is dropped into the polymer-based layer 308 and pushed down to road groove 310. The polymeric material cures securing the mini-marker 325 to the road groove 310.

[0077] Yet another method to provide a mini-marker 325 is to manufacture mini-markers under controlled condition, including the reflective film and the protective overcoat. The mini-markers 325 could be attached to a roll of polymeric film (optionally tinted with coloring for a road marking stripe) with the proper spacing between mini-markers 325, then rolled on to the pavement with pressure to locate them to the bottom of the paint or thermoplastic while it is still wet. In another embodiment, the polymeric film is held to the pavement with polymeric adhesive, and the mini-markers 325 are held by their attachment to the polymeric film.

[0078] An embodiment of the mini-markers 325 can be applied to Epoplex LS90 polyurea liquid pavement marking system while it is still wet or a thermoplastic substrate while it is still hot. The design shown will lock the mini-marker to the surface after the substrates have hardened. One embodiment would use an Epoplex LS90 polyurea liquid pavement marking system at a thickness of 20 mils ± 10, 5, or 2 mils.

[0079] In an embodiment a rolled road lane marking system 475 for applying the protrusions (or mini-markers) 425 comprises a series of mini-markers 425 regularly spaced on a release film 470. Protrusions as described are referred to as mini-markers 425 in this embodiment. The mini-markers 425 (i.e., the longest dimension of the mini-markers 425) run approximately perpendicular to the longest dimension of the release film 470. (Approximately perpendicular here is within 15 degrees of perpendicular.) The release film 470 is lightly bonded with an adhesive to a flat top portion 426 of each mini-marker 425. The system 475 can be rolled up for storage and unrolled to apply the mini-markers 425 to the pavement 412. In an embodiment, the mini-markers 425 are unrolled onto a wet or uncured, colored, polymer-based layer 408, (e.g., a polyurea-based paint strip) that is disposed in a groove 410 running laterally with the length of the road. The polymer-based layer 408 then dries/cures and firmly bonds to the mini-markers 425. After a few minutes, e.g., 2 to 20, or 3 to 10, or 4 to 8 minutes, even before full cure, the release film 470 can be removed without dislodging the mini-markers 425.

[0080] In an embodiment, a large roller can be run along over the application system pushing the mini-markers 425 firmly to the pavement so they bottom out at the correct and consistent height on the pavement. The roller can roll over the release film 470 with the mini-markers 425 underneath. In an embodiment, the mini-markers 425 are disposed into a recessed strip, where the roller can contact both sides of the raised pavement around the recessed strip and only the top portion of the mini-markers 425 that extends out of the recessed strip, so as not to disturb the not-fully-cured polymer-based layer 408. In another embodiment, the circumference of the roller is large enough so that it does not contact the paint, and only contacts the tops of the mini markers 425. [0081] In another embodiment, a pick-and-place machine can be used to place the mini-markers 425 onto the pavement. For example, this may be a vacuum-equipped robotic arm that can move along the length of the road surface along with a supply of mini-markers 425.

[0082] What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable modification and alteration of the above devices or methodologies for purposes of describing the aforementioned aspects, but one of ordinary skill in the art can recognize that many further modifications and permutations of various aspects are possible. Accordingly, the described aspects are intended to embrace all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term “includes” is used in either the details description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim. The term “consisting essentially” as used herein means the specified materials or steps and those that do not materially affect the basic and novel characteristics of the material or method. All percentages and averages are by weight unless the context indicates otherwise. If not specified above, the properties mentioned herein may be determined by applicable ASTM standards, or if an ASTM standard does not exist for the property, the most commonly used standard known by those of skill in the art may be used. The articles “a,” “an,” and “the,” should be interpreted to mean “one or more” unless the context indicates the contrary.