Road marker system and method of installation

A road marker having a stiff but resilient body including a cavity formed therein to receive a suitable adhesive material for securing the marker to the road surface, and adaptable for the inclusion of one or more apertures in said body to receive one or more hermetically sealed lens and retro-reflector elements prior to adhesion of the road marker to the roadway. The body of the road marker is formed with a continuous edge portion and a frusto-conical central portion configured so as to limit contact between vehicle tires and the outer lens surface which may be disposed therein, thereby limiting abrasion and extending the useful life of the road marker. The body of the road marker also includes an aperture to receive a nail in order to facilitate installation of the road marker on the road surface.

FIELD OF THE INVENTION 
The invention relates generally to road marker devices, and relates more 
specifically to a system of resilient-bodied road marker devices adapted 
to receive hermeticallly sealed lens and retro-reflector elements, and to 
a method of installation of the road marker devices on the roadway. 
BACKGROUND OF THE INVENTION 
It has for some time been common practice to employ both reflective and 
non-reflective roadway markers adhered to the roadway surface to delineate 
traffic lanes and other traffic flow patterns. Because such road markers 
are disposed directly upon the road surface they are subjected to frequent 
direct impacts from the tires of vehicular traffic, necessitating that 
such road markers be constructed of high strength, impact resistance 
material. This criteria has been typically met by utilizing road marker 
bodies of ceramic or rigid plastic construction, often filled with epoxy 
resins or similar materials. Such an approach to road marker construction 
is exemplified by U.S. Pat. No. 3,392,639. Such rigid road marker bodies 
have had several disadvantages, most notably a tendency to fracture upon 
repeated impact by vehicular traffic. Such road marker bodies may fracture 
into several pieces and lose adhesion to the road surface, creating a risk 
of serious damage or injury if such pieces are thrown by the wheels of 
passing vehicles. 
Another approach which has been attempted in the prior art has been 
construction of road marker bodies of a soft rubber or rubber-like 
material, as exemplified by U.S. Pat. No. 3,693,511, in an effort to 
alleviate the disadvantages associated with hard, rigid road marker 
bodies. While such an approach is effective in avoiding the problems of 
road marker body fracture, soft rubber or rubber-like road marker bodies 
are themselves subject to certain disadvantages. Excessively soft and 
flexible read marker bodies are subject to deformation leading to release 
of retroreflector elements from such bodies, with corresponding loss of 
road marker function. In addition, such materials may suffer accelerated 
deterioration when exposed to the effects of intense sunlight and of wide 
ranges of cyclic variation in ambient temperature. 
In order to provide a retroreflextive road marker readily visible during 
periods of darkness it has been common practice to incorporate one or more 
reflective elements and glass or plastic lenses into the road marker body. 
Both separated reflective elements and lenses and unitary reflector-lens 
combinations have been used in the prior art, as illustrated by U.S. Pat. 
No. 3,971,623 and U.S. Pat. No. 3,392,639, respectively. In many 
situations it is common to utilize reflective elements of different 
colors, and in some instances to utilize different colors on opposite 
sides of the same road marker. It has also been common to utilize road 
marker bodies of differing colors. Most road markers in the prior art have 
the retroreflective elements incorporated into the road marker body during 
construction, requiring the maintenance of relatively large inventories of 
road markers of the various combinations used. 
In addition to this disadvantage, road markers in common use have enjoyed 
relative short effective life spans due to either failure of the road 
marker body or, more typically, deterioration of reflective qualities 
resulting from incursion of water and other contaminants, the effects of 
sunlight, and abrasion of the outer lens surface from vehicular impact. 
These problems have necessitated frequent removal of deteriorated road 
markers and their replacement with new road markers, an expensive and 
labor intensive process. 
From the foregoing, it will be apparent that there has been a need for a 
road marker system which alleviates the problems and disadvantages of 
maintenance of large inventories of road markers of differing types, of 
short effective life span, and of the labor intensive nature of road 
marker installation. 
SUMMARY OF THE INVENTION 
The present invention overcomes the major disadvantages of the prior art by 
providing a stiff by resilient road marker body adapted to receive 
interchangeable hermetically sealed retroreflector and lens elements, of 
such design that the exposed lens surface, when inserted in the road 
marker body, is substantially protected from direct vehicular impact. The 
present invention further provides a method of road marker installation 
which results in the bonding of the retroreflector and lens element with 
the body of the road marker and facilitates the adhesion of the road 
marker to the road surface. 
The road marker generally comprises a resilient body having cavities 
therein, including a continuous peripheral rim, a planar peripheral 
surface, and a frusto-conical central portion, all mutually concentric 
about the central axis of the body. The road marker body further includes 
a shallow inner base cavity of modified torroidal shape, open at its 
bottom surface. The frusto-conical portion of the road marker body 
includes apertures on opposing sides thereof, extending into the body of 
the road marker and connecting with the shallow base cavity in the 
interior of the body. A plurality of cylindrical cavities extend into the 
frusto-conical portion of the body from the upper surface of the shallow 
base cavity in a direction parallel to the central axis of the road marker 
body. The body is further penetrated by a central aperture coaxially 
aligned with the central axis of the body, to receive a nail which will 
extend into the road surface upon which the road marker is to be 
installed. 
The road marker of this invention further comprises retroreflector and lens 
elements to be received in the apertures formed in the frusto-conical 
portion of the road marker body. Such elements include a shell-like body 
having a rear wall, two side walls, a top wall, a curved and angled front 
wall, and a dividing wall intermediate the rear wall and the front wall. 
Retroreflective means is disposed in the front chamber of the element body 
and attached to the inner surface of the front wall of that body. The 
front chamber is filled with a suitable potting compound to fully seal 
that chamber and prevent incursion of contaminants. Element bodies are 
then inserted into the apertures in the frusto-conical portion of the road 
marker body until the outer surface of the front wall of each element body 
is flush with the outer surface of that frusto-conical portion. 
The insertion of such element bodies into the road marker body may be 
performed immediately prior to installation of the road marker on the road 
surface, allowing use of a generic road marker body with various 
combinations of retroreflector color. After insertion of the 
retroreflector and lens elements into the body of the road marker, the 
road marker is inverted and the cavities therein, including the rear 
chambers of the retroreflector and lens elements, are filled with a 
suitable adhesive compound. The road marker is then placed with its base 
and the contained adhesive in contact with the road surface and affixed 
thereto by driving a nail through the central aperture in the road marker 
body and into the road surface. 
These and other features and advantages of the present invention will now 
be disclosed in greater detail with reference to the accompanying drawing 
figures, wherein

DETAILED DESCRIPTION OF THE INVENTION 
With reference to FIG. 1, it will be seen that the preferred embodiment of 
the road marker system of this invention generally comprises road marker 
body 10, retroreflector and lens elements 40, and nail 60 as its major 
components. Each component will be described, followed by a description of 
the method of use and installation of such road marker system on the 
roadway. 
Referring principally now to FIG. 1 through FIG. 4, road marker body 10 is 
preferably molded of a stiff by resilient material as a unitary or one 
piece construction. Body 10 includes continuous peripheral rim 12, planar 
peripheral surface 14, and frusto-conical central portion 16, all mutually 
concentric about the central axis of body 10. The relation between the 
width of planar peripheral surface 14 and the height of frusto-conical 
central portion 16 above such surface is such that a plane intersecting 
the outer edge of the upper surface of frusto-conical portion 16 and the 
outer edge of peripheral planar surface 14 does not intersect any portion 
of the inclined surface of such frusto-conical portion. By virtue of this 
design element, the impact of vehicle tires upon road marker body 10 will 
be largely confined to such edges and impact upon the inclined surface of 
such frusto-conical portion of the road marker body will be reduced or 
eliminated. As hereinafter described, the lens surfaces of retroreflector 
and lens elements 40 will be disposed flush with such inclined surface. 
The minimization or elimination of tire impact thereon results in a 
substantial reduction in lens surface abrasion with a corresponding 
increase in useful road marker life span. 
Body 10 is formed to provide an inner base cavity comprising two portions; 
an outer torroidal portion 18 bordered on its outer edge by the lower 
inner surface of continuous peripheral rim 12 and on its top by surface 20 
and a continuous inner torroidal portion 22 which extends farther into the 
interior of body 10 and surrounds inner support 24. 
Frusto-conical portion 16 of body 10 includes apertures 26 extending 
laterally into body 10 in opposing relationship about a common 
longitudinal axis perpendicular to the central axis of body 10. Apertures 
26 receive retroreflector and lens elements 40 and are configured to 
receive such elements in close mating relationship. Apertures 26 extend 
downward a short distance into the planar peripheral portion 14 of body 10 
to provide retroreflector and lens element support surfaces 28 and 
retaining lips 30. The parts of such apertures 26 inward from the inner 
edges of element support surfaces 28 are contiguous to and coextensive 
with inner portion 18 of the inner base cavity of body 10. Additional 
apertures 32 extend into body 10 from the upper surface of the inner 
portion 18 of the base cavity of body 10 toward the top surface of 
frusto-conical portion 16. The longitudinal axes of apertures 32 are 
parallel to the central axis of body 10 and are contained in a plane 
perpendicular to the longitudinal axis of apertures 26. Body 10 is fully 
penetrated by central aperture 34, coxially aligned with the central axis 
of body 10, which will receive nail 60 during installation of the road 
marker on the road surface. 
Road marker body 10 is preferably molded as a one-piece construction of 
thermoplastic elastomer material of sufficient strength and durability to 
withstand repeated vehicular impacts without destruction or loss of 
integrity. The material of construction should also be sufficiently 
resilient to cushion or absorb the force produced by vehicular impact with 
sufficient stiffness to avoid excessive deformation detrimental to 
maintenance of the structural integrity of road marker components and the 
adhesive bond among such components and between the road marker and the 
roadway upon which it is installed. The material of construction should 
still further be capable of maintaining the desireable characteristics of 
resilience, strength, and durability though the range of variation of 
ambient temperatures to which the installed road marker may be subjected. 
It has been found that a polyester elastomer, such as that produced under 
the trade name Hytrel, having a Shore hardness of 90A or 55D provides 
suitable characteristics within such criteria. Road marker body 10 may be 
colored to meet usage criteria, preferably by full integration of a color 
additive into the construction material prior to molding, providing full 
color penetration. 
Referring now to FIG. 5 and FIG. 6, retroreflector and lens elements 40 
will be seen to each comprise a shell-like body 42, having a top wall 44, 
side walls 46, rear wall 48, and lens 50 as the front wall. Element body 
42 is open at its bottom wall and is divided into front chamber 52 and 
rear chamber 54 by dividing wall 56, disposed intermediate rear wall 48 
and lens 50 and parallel to rear wall 48. The outer surface of lens 50 
will lie flush with the outer inclined surface of frusto-conical portion 
16 of road marker body 10, and is of the same inclined convex curvature. 
Lens 50 is preferably thinner in cross-section than walls 44, 46, 48, and 
56, so as to maximize transmission of both incident and retroflected light 
while maintaining the structural integrity of element body 42. Element 
body 42 is preferably of molded one piece construction from a rigid, 
abrasion resistant transparent material. In the preferred embodiment, 
element body 42 is constructed of Lexan (TM) polycarbonate, but any other 
material of suitable characteristics may be used. The outer surface of 
lens 50 is preferably coated with an abrasion resistant silicone material. 
Such coating may be applied in liquid form, and subsequently cured to a 
hard solid state. 
Retroreflector and lens element 40 further includes retroreflector means 56 
disposed in front chamber 50 with its front or outer surface in full 
mating relationship with the inner surface of lens 50. In the preferred 
embodiment retroreflector means 56 comprises a colored metalic tape and is 
attached to the inner surface of lens 50 with a transparent ultra violet 
radiation absorbing adhesive compound. Use of an ultra violet radiation 
compound is preferred in order to minimize the deteriorating effects of 
sunlight on retroreflector means 56 and extend its useful life span. 
However, alternate embodiments of a retroreflector means known in the 
prior art may be effectively utilized, such as a molded array of prismatic 
reflector units. 
The remainder of front chamber 52 is filled with a suitable potting 
compound which cures to a hard, rigid material, providing a hermetic seal 
against incursion of water and other contaminants in order to prevent 
fogging and chemical deterioration of lens 50 and retroreflector means 56, 
as well as increasing the strength of retroreflector and lens element 40. 
Nail 60, the third major component of the road marker system, will be seen 
from FIG. 7 to comprise head 62, transition zone 64, shaft 66 and point 
68. Shaft 66 has a diameter essentially equal to the diameter of central 
aperture 34 in road marker body 10, and is of sufficient length to fully 
penetrate body 10 through central aperture 34 and extend into the road 
surface a sufficient distance to firmly anchor the road marker thereto. 
The length of shaft 66 may be varied to accomodate anchoring in different 
types of road surfaces. Head 62 is of sufficiently larger diameter than 
shaft 66 and central aperture 34 as to retain road marker body 10 in firm 
contact with the road surface. Transition zone 64, an inverted 
frusto-conical section, is designed to penetrate into the upper segment of 
central aperture 34, thus increasing the frictional resistance against 
movement of road marker body 10 relative to nail 60, and providing a 
larger effective retention surface area. Shaft 66 tapes smoothly to point 
68 in order to facilitate penetration of nail 60 into the road surface. 
The method of use of the road marker system of the present invention 
comprises the general steps of inserting retroreflector and lens elements 
40 into road marker body 10; inverting the thus completed road marker and 
filling rear segments 54 of elements 40, apertures 32 and portions 18 and 
22 of the inner base cavity with a suitable adhesive compound; reinverting 
the adhesive filled road marker and placing it in the desired location on 
the road surface; introducing nail 60 into central aperture 34; and 
driving nail 60 through such aperture and into the road surface until the 
lower surface of head 62 is in firm contact with the upper surface of 
frusto-conical portion 16 of the road marker and the road marker base is 
in firm contact with the road surface. As the adhesive compound cures an 
internal interlock is formed between road marker body 10 and 
retroreflector and lens elements 40 by virtue of the internal 
communication between road marker body internal cavities and rear chambers 
54 of the retroreflector and lens elements. In similar fashion, the 
extension of adhesive compound into apertures 32 of the road marker body 
serves to increase adhesion between road marker and road surface. Use of 
nail 60 to attach the road marker to the road surface provides initial 
stabilization of the road marker on the road surface during curing of the 
adhesive compound; maintains pressure between road marker, adhesive, and 
road surface during curing of the adhesive compound; and serves as an 
additional attachment means during the life of the road marker, minimizing 
the possibility of dislocation. It will, however, be understood that use 
of nail 60, while facilitating installation of the combined road marker 
body and retroreflector and lens elements, may be omitted without 
departing from the scope and spirit of the invention. 
It will be apparent that retroreflector means of various colors may be 
utilized in the construction of retroreflector and lens elements 40 in 
order to achieve reflection of light of a selected color in order to meet 
use criteria. Because road marker body 10 and retroreflector and lens 
elements 40 are designed to be separately formed and then combined to 
produce a completed road marker, it will also be apparent that a wide 
variety of completed road marker configurations can be achieved from a 
limited variety of individual components. For example, an inventory of 
road marker bodies in two colors and of retroreflector and lens elements 
in three colors allows combination of these elements into twelve distinct 
completed road marker configurations. 
The road marker system of the present invention may be readily adapted to 
provide a unidirectional retroreflective road marker or a non-reflective 
road marker by omitting one or both of apertures 26, respectively, in the 
forming of road marker body 10, and the corollary omission of one or both 
of retroreflector and lens elements 40 from the completed road marker. 
Alternatively, a unidirectional retroreflective road marker or 
non-reflective road marker may be provided by forming body 10 as 
previously described and replacing one or both of retroreflector and lens 
elements 40 in the completed road marker with suitably colored 
non-reflective inserts of the same gross configuration and size as the 
retroreflector and lens elements 40 previously described. Such inserts may 
be constructed by omission of retrorelfective means 56 from elements 40 
and filling of front chamber 52 with a suitably colored potting compound, 
or by monolithically forming such inserts from the same material utilized 
for construction of the road marker body. 
It is apparent that the present invention is well adapted to obtain the 
advantages and features set forth, together with other advantages which 
will become obvious to one skilled in the relevant art. The foregoing 
disclosure of the invention is only illustrative and explanatory, and the 
invention admits of changes in size, shape, and composition of its 
components without departing from the scope and spirit thereof.