US 2666373 A
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Description (OCR text may contain errors)
E. c. MATTSON TRAFFIC MARKER Jan. 19, 1954 2 Sheets-Sheet 1 Filed June 29, 1950 Ill/Ill, E/berzf G Mofi on I ATTOPNEYS 'Jan. 19, 1954 E. c. MATTSON 2,666,373
TRAFFIC MARKER Filed June 29, 1950 2 Sheets-Sheet 2 mu -m IN V EN TOR.
A TTOPN ZTXS of the marker a multiplicity of concentrically arranged segmentary recesses or cells 29 which are separated circumferentially from each other by main radial bars or ribs 22 and intersecting circumferential bars or ribs 24. It will be observed that in the outer four concentric rings there is disposed auxiliary radial bars 25 between the main radial bars which further circumferentially divide the concentric recesses into additional segments.
At the center of the disc there is provided a conical recessed bore 30 in the upper surface, for receiving a screw or a pin 32 as shown in Figure 5, to assist in anchoring the marker to the pavement. It will be seen in Figure that the marker, as installed, comprises in combination the disc i0 illustrated in Figures 2, 3 and 4 and a coating or film 34 of light reflecting material on the walls of the recesses.
The structural characteristics and the manner of installation of the marker are seen to advantage in the greatly enlarged fragmentary section view, Figure 6. The marker is cemented to the pavement 38 by means of cementitious or mastic material 40, described hereinafter, which enters the recesses for at least a part of their depth, and may, depending on the quantity used and the method of application, completely fill the recesses. The under side of the marker,
with reference to the walls of the recesses, has
been coated with a layer 34 of material to provide a light reflecting surface. Various materials may be used, for example; various paints provide a high quality, light-reflecting surface; powdered metal may be applied as a spray, or as a pigment in a vehicle; metal may be deposited by a plating process; quick silver may be employed as in a silvering process to provide a mirror surface; thin, flexible films may be impressed into the recesses to conform to the walls.
The light reflecting characteristics of the marker, with the light reflecting coating on the recess walls, are shown in general by the schematic representations of light rays in Figure 6. It will be observed that the light rays 42 from a source (not shown) impinge upon the curved upper surface M of the marker, are bent by the lens effect of the curved upper surface and the index of refraction of the transparent material at 44 and then fall upon the mirror-like reflectihg surface provided by the coating 34 on the recess wall, and are reflected back at a slight angle of reflection in the general direction of the light source. In this connection, it is desirable to coordinate the angle of disposition of the outer (toward the peripheral edge of the marker) walls of the recess with reference to the light transmitting characteristics due to the physical shape of the upper surface of the marker, the index of refraction of the transparent material, and
the general direction or angle of incidence of the normal impinging light rays to which the marker is designed to respond as a traffic guide, so that the angle of incidence will be approximately normal (perpendicular) to the outer wall surface of the recess.
A preferred light reflecting material for the coating 34 is that shown (greatly enlarged) in Figure '7. It will be seen to comprise a laminated film 50 having a flexible, elastic backing 52 and a surface layer 54 of minute glass beads of substantially uniform diameter adhesively secured to the backing material by being imbedded in a film or stratum of suitable cement 56. Such a material is that manufactured by the Minnesota Mining 8: Manufacturing Co. of St. Paul, Minnesota, under the trade name Scotchlite. The glass beads are so minute that they are scarcely visible as such to the naked eye, and can be seen only under a microscope. Their relative size is indicated by the fact that Figure 7 is drawn to about thirty magnifications. The laminated fllm has a thickness of only about ten to fifteen thousandths of an inch. This film, by virtue of the discontinuity of the reflecting surface provided by the glass beads, has the property of reflecting light rays back in substantially the same direction as the direction of incidence, as illustrated by the schematic representation of light rays 58, thereby becoming luminous as distinguished from being merely illuminated. The closeness of the angle of reflection to the angle of incidence of the light reflecting characteristics of this material are ably demonstrated by the fact that the reflected light can be seen only substantially in the vicinityof the source of illumination.
When Scotchlite or other prepared film of light reflecting materia1 is used, it is impressed into the recess by suitable means, and made to conform to the walls of the recesses.
As previously pointed .out, the marker is attached to the concrete 38 or other pavement surface by the bonding action of a mastic substance 40 and pin 32, as shown in Figure 5. The mastic provides the necessary bond of the marker to the pavement, but the marker might otherwise slide a considerable distance in the course of a year under the impacts of traffic, all the while retaining its bonding grip on the pavement. Hence, the pin 32 is used to prevent sliding of the marker.
The recesses 25 perform an auxiliary function in connection with bonding the marker to the road surface. The area of the marker for making bonding contact with the mastic is greatly increased by reason of the additional surface provided by the walls of the recesses. Not only 1 is the area of surface contact with the marker greater, but as the mastic is received in the recesses it forms columns which are resistant to the shearing action of forces applied laterally to the marker button. The bonding effect may also be promoted by the vacuum principle if the recesses are completely filled with the mastic be fore applying the disc to the pavement, so that a suction effect is created between the disc and the pavement surface.
In Figures 2, 3, 5 and 6 it will be observed that the intersecting ribs or bars 22, 24 and 26 have flat bases which are narrower than the cells 20 and narrower than the height of the substantially vertical side surfaces of the bars. Thus, the cells extend upwardly considerably more than halfway through the button, leaving a relatively thin top Wall covering the top ends of the cells. It will also be observed that there are a large number of the bars and recesses whereby the area of said side surfaces in the aggregate greatly increases the available surface engagement with the mastic 40, relative to the projected circular area of the button which is available in a smooth bottom type of button. In the Figure 2 embodiment there are 132 small'cells forming a reticulated bottom face to receive the mastic and provide spaces to accommodate lateral distortion of the ribs or bars under heavy compression loads. The ribs or bars which serve as compression members under load are sufficiently numerous to provide good stress distribution and sufliciently 5.. narrow andsufficientl-y spaced to distort into the cell spaces under excess loading without cracking the marker. a
Asphalt, tar, pitch, or other adhesive substance, which has the capacity to adhere to both the substance of the road pavement and the plastic substance of the marker button, may be used. Other desired characteristics of the binder are that it be capable of maintaining its bonding properties through year round conditions of summer heat and winter cold. In other words, it must not become too plastic in summer or too brittle winter. it have found a mixture of rubber and bituminous asphalt to provide the above named characteristics and to be particu larly satisfactory for the purpose. Such a mixture is that sold by Philip Carey Mfg.- Co. of Lockland, Qhio, under the trade name of Gareylastic.
Still another function performed by the recesses in the under side of the marker is in the prevention of warping or cupping of the marker. Traflic markers are used, obviously, undera great range of weather conditions and temperatures. It is well known that pavements absorb the suns heat and are frequently very hot relative to the atmosphere. Experience has shown-that when markers are -made of plastic materials, and solid, with both the upper and under surfaces smooth, the heat absorbed in the pavement causes the marker to expand along its bottom surface, causing it to turn up or cup at the edges, muchthe manner of aboard which warps due to absorption of a greater percentage of moisture on its bottom side than on its upper side. When the marker turns up or cups at its edges in the manner mentioned, it then becomes vulnerable to trafiic impacts, and is quickly cracked, chipped, and broken.
The provision of the recesses 20 in the under surface of the plastic marker has been found to overcome the above-described fault. Warping of. the marker due to excessive expansion of the under side is prevented by the fact that the recesses 20' in the under side constitute a plurality of spaced grooves with alternating ribs interrupting the under surface of the marker and rendering the same discontinuous. The grooves are of such spacing and frequency, and ofa depth such that any expansion forces developed i'n'the body of the marker, or within the rib projections delineated between the grooves 'and' which constitute the under surface, cannot be combined so as to be transmitted from one to the other. In other words, the number of the grooves and their depth'rel'ative to the body of the marker is sufiicient tov prevent accumulation in the underside of the marker of stresses normally arising from shrinking and expansion.
In addition to thefunctions performed bythe recesses, already mentioned, it is desired to point out that a marker having a plurality of interiorly disposed, outwardly presenting facets, as results from the provision of the recesses in a transparent body, has the distinct advantage of presenting. a broken or discontinuous light-refleeting surface, as wilbappear from the showing of. the facets in thepartof-Figure 5 in elevation. This isparticularly eifective in'pr'ovidin'g greater conspicuousness at. night.
While the number offacets and their disposition. is. variable, it isipreferable that they be arranged in. concentric ringsor'rows', with the height of. each facet 'in one rew being greater than the height of the facet invthe next outer row, so that the top portion ofthe nextinwardl y disposed facet is visible over the next adjacent outwardly disposed facet through an arc of ap proximately QO degrees. .In this manner, the facets will be illuminated and visible to the eye by light rays falling thereon through the angle from horizontal to vertical. n
Figures 8 and 9 illustrate modified forms of the invention wherein the marker button is made of two parts, a convex-concave cover member with an internally presenting lip, and a body member designed to conform to the concave side of the cover member and to be received within the cover member in a press or snap fit similarto the manner of a snap fastener. This embodiment of the invention is particularly designed to receive between the cover member and the body member a film of Scotchlitef or otherlight reflecting material. Of course, the under surface of the cover member, or the upper surface of the body member, may be coated with light reflecting material, as previously shown in connection with the embodiment shown in Figures 2 to 5.
Referring more particularly to Figures 8 and 10, the concavo-convex cover member is designated by the numeral 60, and is provided with an internally presenting lip 62 at the inner, bottom edge. The lip 62 causes to be formed an annular recess 64 around the inner-edge of the cover member. The cover member is provided with a conical bore 66' at its center for receiving the head of the pin for anchoring the marker assembly, as in the embodiment shown in Figures 2 to 5.
The body member 68 is provided with a convex upper surface corresponding in contour to the concave under surface of the cover member, and has its peripheral edges lll designed to be re-' ceived in close fittingrelation within the recess 64 formed by the inwardly presenting lip 62 of the cover member. The bottom of the body member is fiat, but provided witha plurality of recesses 69 formed by a grid pattern of intersecting radial ribs and circumferential ribs, in a manner similar to the under side of the marker illustrated in Figure 2.' Ifhe overlap of the peripheral edge 10' of the body member till as rece'ived within the confines of the lip 62 of the cover member is delineated by the dotted line shown in Figure 10. Afilm of "Scotchlite 12 is interposed between the cover member and body member, as illustrated The Scotchlite is preferably cut ina disc of a diameter such that its edges do not extend into the recess 64 but stop at approximately the point 74 as illustrated in the drawings v While the cover member 60 is illustrated in Figure 8 as beingprovided with an aperture 66 at its center, it willbe understood that only the body member 68 need be provided with a conical bore for receiving the pin, and, if the bore is sufficientlyrecessed in the body member to com-- pletely receive the pin head, then the cover may be made completely continuous without the eeri tral opening. In such case the marker button is installed by first securing the body member to the concrete or other pavement surface, next positioning the film of Scotchlite, and then snapping the cover' member over the body member ,as installed. Installation of the body member'as a separateunit, or the combin'a'tion of the body member and the cover member when'as- "tsembled 'u t. accomplished in the same manner as previously described for the embodiment in Figure 5.
Advantages of this embodiment are that the Scotchlite may be used and inserted as a flat film without the necessity of pressing it into recesses in the under side of the button, as previously disclosed in connection with the embodiment described in Figures 2 to 5; and only the cover member 60 need be made of transparent plastic material having a high, Wear-resistant quality, which material is usually more expensive than other plastic materials. The body member, since it is not subject to wear or spalling, may then be made of less durable, cheaper plastic materials, or of wood, metal or other suitable material. Road maintenance of the tramc marker button, as made of two parts, is cheaper because only the cover member needs to be replaced should it become worn or broken.
The embodiment of the invention illustrated in Figure 9 is a two piece trafiic marker comprising a cover member 88 and a body member 8|. The cover member 88 is provided with an inwardly presenting lip 82 at its inner, bottom edge, which causes to be formed an annular recess 84 around the inner edge of the cover member. It will be seen that the construction in this respect is identical to that illustrated in Figure 8. However, the cover member 80 diiiers from the cover member 68, illustrated in Figure 8, in that the cover member 80 is provided with a series of concentric, stepped annular channels 85, or series of other circumferentially arranged deformations on its under side. These channels may be arcuate, as illustrated in the drawing, or they may take an angular form, as desired. Each concentric ring need not necessarily be continuous, but may be discontinuous, comprising a series of arcuate segments or series of other circumferentially arranged deformations. The body member 8! is then constructed with its upper surface provided with a series of corresponding, complemental concentric ribs or projections 86 to conform in contour to the under surface of the cover member. A film 8'! of Scotchlite, or of other light reflecting material, is disposed be- I tween the two members.
Another variation in the construction illus-,
trated in Figure 9 from that illustrated in Figure 8 is in the matter of depth of the recesses 88 pro vided in the bottom of the body member 8|. While the arrangement and disposition of the recesses is the same as in Figure 8, and, therefore; the bottom plan view for both Figures 8 and 9,
is identical, and is as disclosed in Figure 10, the recesses 88 in the under surface of the body member of Figure 9 are not constructed as deep as those in Figure 8. It will also be appreciated that the recesses may be entirely omitted, if desired, although then the bonding action of the mastic used to cement the marker to the pavement will be reduced.
An advantage of the embodiment illustrated in Figure 9 over that shown in Figure 8 is that the exterior of the marker will present to the ob server a series of concentric rings, or facets if the under surface of the cover member 80 is constructed with recesses as above described, which thereby make it more conspicuous to the observer.
Figure 11 illustrates a variation in the grid pattern of the recesses with which the bottom of the body member may be constructed. In lieu of the intersecting radial and circumferentially extending ribs, the bottom surface is provided 8 with uniformly arranged square recesses 89, resembling a wafiie iron. It will be appreciated that this design for the bottom surface may be used on any of the embodiments illustrating the invention, including the single piece body member illustrated in Figures 2 to 5.
Figure 12 illustrates still another grid pattern for the bottom surface of either the body member or for a single piece marker button.
Figure 13 illustrates still another embodiment of a two piece marker button comprising a cover member 88 and a flat disc-like plate I08 adapted to be received within the recess 98 provided in the under side of the cover member. The member 98 may be provided with a plurality of recesses as in its under side similar to the recesses illustrated in Figures 2-5. The periphery 94 of the cover member 88 is shaped to form an inwardly presenting lip 86 and recess 98 as described in connection with Figures 8 and 9. The relatively thin flat plate member I88 is received within the recess 98 in close fitting, snap, or detent-like action to thereby complete the bottom surface for the marker button. A film I82 of Scotchlite or other light reflecting material is disposed between the member 98 and the bottom plate I in a manner similar to the disclosure of Figure 8.
Figure 1% represents still another modification oi the invention. The marker button in this embodiment is constructed quite similarly to the marker buttons of Figures 2 to 5, except that a relatively deep endless recess, illustrated in Figure 1% as an annular channel H0, is provided in the bottom of the button, between the center and peripheral edge of the button. A cylinder l l2 of Scctchlite or other light reflecting film is then inserted in the annular channel, and light rays ii i falling on the marker button are then reflected from the Scotchlite in the manner shown in the drawing. It will be appreciated that the channel, recess, or groove for receiving the film of light reflecting material is preferably constructed of a width just suflicient to receive the film. The recesses H8 in the bottom side of the marker are not constructed as deep as in the case of Figures 2 to 5, so that the cylinder of light reflecting material will be clearly visible. In other respects, the construction of the marker button is similar to that of Figures 2 to 5.
It will be understood that various further modifications will occur to persons skilled in the art, and that various combinations of the features and embodiments disclosed herein may be made within the contemplation of the invention. For instance, the design pattern of the recesses is probably infinitely variable. The marker button may be made from a single piece of material, or may be of divided construction with a transparent outer shell or cover member. Different arrangements and designs may be provided for positioning the light reflecting material within or under the marker button so as to be visible through the transparent material of the marker button itself. The bottom surface of the marker may or may not include recesses, but recesses are preferred for the increased bonding action they provide, even if alternative means are provided for positioning the light reflecting material Within the marker body. The body member, or bottom-seal member IUD of Figure 13, in the twopiece embodiments of the invention, need not necessarily be secured Within the cover member in the manner herein illustrated and described, but may be secured in any other appropriate manner, as by press fit, screwing, crimping, pinning, etc.
Having thus described the invention, what is desired to be secured by Letters Patent is:
1. A non-warping traific marker adapted for bonding to the trafilc surface of a pavement, made of molded plastic which has a coeflicient of linear expansion more than five times that of steel and consequently having a tendency to curl when subject to extreme heat on ahot road surface, the marker having a reflective convex upper surface to reflect heat and a fiat lower face, and a large number of independent cellsin said lower face, said cells being separated by a plurality of intersecting bars, the wall of said cells as defined by said bars presenting a large substantially vertical surface area to a bonding material for securing said marker to a pavement surface, and the reduced surface contact of the bars with the pavement interrupting said lower face to reduce transfer of heat from the pavement and relieve expansion strains thereby reducing the curling tendency of the marker, said bars supporting the marker and being distortable to sustain heavy loads without damage to the marker.
2. A trafiic marker as defined in claim 1 in the shape of a relatively thin circular-button having a hollow central supporting boss adapted to receive a metal anchor pin.
3. A traffic marker as defined in claim 2 wherein said intersecting bars comprise radially spaced circular ribs concentric with said central boss, and arcuately spaced radial ribs radiating outwardly from said central boss.
4. A non-warping traffic marker adapted for bonding to the traffic surface of a pavement, comprising a relatively thin circular button of molded plastic material which has a relatively high coefiicient of expansion, said button having a smooth, reflective convexly curved top surface and a fiat reticulated bottom face to receive a mastic material for securing the marker to said trafiic surfac of a pavement, no portion of said plastic button projecting below said bottom face, said bottom face comprising a large number of closely spaced intersecting flat bottom supporting bars, substantially vertical side surfaces on said bars extending down to said bottom face and defining a large number of small closely spaced cells, said cells extending upwardly more. than halfway through the thickness of the marker, th flat bottoms of said bars being narrower than said cells and narrower than the height of said side surfaces, and the length of said bars in the aggregate being sufficiently great that said side surfaces of the bars present a large mastic bonding area, the reduced surface contact of the bars with the pavement interrupting said lower face to reduce transfer of heat from the pavement and relieve expansion strains, thereby reducing the curling tendency of the marker, said bars supporting the marker and being distortable into said cells to sustain heavy loads without damage to the marker.
5. A tramc marker as defined in claim 4 wherein said circular button has a hollow central integral supporting boss adapted to receive a removable metal anchor pin, and wherein said intersecting bars comprise radially spaced circular ribs concentric with said central boss and arcuately spaced radial ribs radiating outwardly from said central boss.
ELBERT C. MATTSON.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,685,449 Durand Sept. 25, 1928 ,746,312 Lee Feb. 11, 1930 1,963,748 Woolums et al Apr. 11, 1933 1,920,502 Myers Aug. 1, 1933 1,952,471 Stern Mar. 27, 1934 1,981,206 Strauss Nov. 20, 934 1,986,097 Arey Jan. 1, 1935 2,021,759 White NOV. 19, 1935 2,256,636 AbbOtt Sept. 23, 1941 2,321,476 Foster June 8, 1943 2,328,407 Becker Aug. 3 1943 2,354,857 Gits Aug. 1, 1944 2,489,499 Pellar NOV. 29, 1949 FOREIGN PATENTS Number Country Date 360,761 Great Britain Nov. 12, 931 823,963 France Oct. 25, 1937 OTHER REFERENCES Modern Plastics, article on pag 159, vol. 27, No. 5, January 1950. Publ. by Modern Plastics, Inc., New York city.