The present invention relates generally to guardrails and more particularly to a pultruded composite guardrail.
Guardrails are commonly installed along roadways and other areas to control the direction of traffic flow and to prevent vehicles from leaving the roadway. The most common type of guardrail is a steel, W-beam guardrail (i.e., guardrails which typically have a w-shaped cross-section). The steel may be galvanized to help the guardrail resist corrosion.
Typically, metal or wooden posts are driven into the ground along the edges of a roadway and the guardrails are bolted to the posts to form a continuous barrier running parallel to the roadway. A space block may be inserted between a guardrail and a post to space the guardrail away from the post and to mitigate contact between the post and the wheels of an impacting vehicle. The ends of each guardrail may be formed so that adjacent guardrails may overlap and nest with each other. Alternatively, the ends of two adjacent guardrails may be butted together and held in place by a connecting member. Steel guardrails have several inherent drawbacks. For example, due to their weight, steel guardrails are difficult to transport, install, repair, and remove. Thus, high labor costs are associated with the transportation, installation, repair, and removal of steel guardrails.
Another inherent problem related to steel guardrails is that even a minor collision may necessitate the replacement of the guardrail. For example, a minor collision may cause the guardrail to deform, thereby reducing its ability to absorb a subsequent collision. Also, a minor collision may cause the galvanized coating to be damaged, thereby increasing the susceptibility of the guardrail to corrosion and decreasing its lifespan.
Yet another inherent problem with steel galvanized guardrails is that due to environmental conditions, such as rain, sleet, snow, fog, etc., the zinc galvanized coating may leach into the ground contaminating the soil or the water table near the guardrail.
Another inherent disadvantage for steel guardrails is a lack of aesthetic appeal. Typically, steel guardrails are silver in color and are incapable of blending into the natural surroundings. Although steel guardrails can be painted, this increases the overall cost of the steel guardrail.
Plastic and composite guardrails have been proposed as an alternative to steel guardrails. For example, U.S. Pat. No. 4,681,302 to Thompson illustrates a hollow plastic guardrail section, two or more of which may be joined end-to-end and which may be filled with water to enhance energy dissipation. U.S. Pat. No. 3,540,699 to Guzzardella describes a guardrail having similar operation. U.S. Pat. No. 4,307,973 to Glaesener illustrates a guardrail having a sheet-metal shell filled with synthetic resin foam. U.S. Pat. No. 4,138,095 to Humphrey illustrates a guardrail having a hollow plastic base which may be filled with ballast and draped with baglike impact shields filled with sand or other granular material.
Additionally, U.S. Pat. No. 6,149,134 to Bank et al. is directed to a guardrail system including a rail and rail connectors wherein the rail is formed of several elongated tubes which are integrally molded at the tube sidewalls. The tubes preferably have polygonal cross-sections with sidewalls situated in horizontal and vertical planes, with the vertical sidewalls of the various tubes staggered at different depths within the rail. Connections between rails may be achieved by internal connectors which fit within the tubes of adjacent rails, and/or by use of external connectors which receive the ends of adjacent rails. Such internal and external connectors may also be used to reinforce damaged rails to restore their performance characteristics. All of the above-identified United States patents are incorporated herein by reference.
The guardrail systems disclosed by the prior art, however, are difficult to install. For example, the guardrail system disclosed by Bank requires the installation of complicated rail connecters to join adjacent guardrails. Additionally, the guardrail systems disclosed by the prior art are more difficult to manufacture. For example, a complicated pultrusion die or mold must be created to form the guardrail and connection components.
Thus, there exists a need for a pultruded composite guardrail that resists corrosion, is easy to manufacture, install, and repair, and that overcomes these and other limitations of prior art guardrails. There is also a need for a guardrail that is friendly to the environment, soil and ground water in the vicinity of the guardrail installation.
One aspect of the present invention relates to a pultruded composite beam or guardrail for a guardrail system, including one or more layered reinforcement materials and a resin permeating the one or more layered reinforcement materials, the one or more layered reinforcement materials and resin forming a solid shaped guardrail member when the resin is cured.
Another aspect of the present invention relates to a one-piece, unitary and formed or shaped guardrail (or guardrail beam) constructed of pultruded composite material including one or more reinforcement materials set in a plastic resin, such as polyester or poly-urethane resin.
Another aspect of the present invention relates to a guardrail system having one or more posts and one or more pultruded composite guardrails secured to the posts. The guardrail system may further include at least one spacer block attached to each of the posts, the spacer block for carrying one or more of the pultruded composite guardrails, an anchor attached to at least one of the posts, a splice plate coupling a plurality of the pultruded composite guardrails together, and a plurality of fasteners for joining together the components of the guardrail system.
Another aspect of the present invention relates to a method of manufacturing a pultruded composite guardrail comprising pre-forming one or more reinforcement materials, saturating the pre-formed reinforcement materials with a resin, pulling the resin-saturated reinforcements through a pultrusion die, heating the resin saturated reinforcement in the pultrusion die to solidify the resin, and cutting the pultruded composite guardrail to length.
To enable the present invention to be easily understood and readily practiced, the present invention will now be described for purposes of illustration and not limitation, in connection with the following figures wherein:
Referring to
The pultruded composite guardrail beam 10 is of unitary construction, but can be viewed as a series of interconnected face plates and angled legs to provide the desired functional performance characteristics of longitudinal tensile loading capacity in the face places and transverse stiffness in the legs. The dimensions of the face plates and legs can be chosen to achieve the desired beam height and depth (or width). In one embodiment, the pultruded composite beam includes three sections: a top section 16, a middle section 18, and a bottom section 20. Each section 16, 18, 20 is comprised of two legs and a face, such that the top section 16 includes a face 16b and two legs 16a, 16c, the middle section 18 includes a face 18b and two legs 18a, 18c, while the bottom section 20 includes a face 20b and two legs 20a, 20b. The top and bottom sections 16, 20 are connected to the middle section 18 by a top back member 17a and a bottom back member 17b, respectively.
The top section 16 and bottom section 20 are shown, in one embodiment, having the same or substantially same dimensions with the legs 16a, 16c, 20a and 20c measuring 4.25 inches (10.79 cm) and the faces 16b, 20b measuring 2.026 inches (5.146 cm). In the embodiment shown, the dimension of the face 18b of the middle section 18 is greater than the top and bottom faces 16b, 20b of the top and bottom sections 16, 20. The face 18b is shown measuring approximately 3.95 inches (10.04 cm) high. The top and bottom back members 17a, 17b are approximately 1.518 inches (3.856 cm) high. In other embodiments, the legs 16a, 16c, 20a, 20c measure between about 4 and 6 inches and the faces 16b, 20b measure between about 1.5 and 4 inches, the face 18b may measure between 1.5 and 6 inches, and the top and bottom back members 17a, 17b measure between 1 and 3 inches. In yet another embodiment, the dimension of the face 18b is less than the top and bottom faces. Other dimensions may be used.
As illustrated in
It should be apparent to one skilled in the art that the dimensions used are provided for exemplary purposes only and are in no way intended to limit the scope of the present invention.
Returning to
The faces 16b, 18b, 20b are substantially flat and are positioned to lie in a substantially same plane. Further, the faces 16b, 18b, 20b are positioned such that when the guardrail 10 is installed, the faces 16b, 18b, 20b (front portion) face a roadway 100 and are designed to be positioned substantially vertical to the plane of the roadway and run (along the length of the guardrail 10) substantially parallel to the roadway (see
In one embodiment, the composite pultruded guardrail 10 has a multitude of holes or apertures 22a formed in the guardrail 10 at various locations. The holes or apertures 22a are operable for receiving fasteners for coupling one guardrail to another guardrail and/or for coupling to a splice plate. In the embodiment shown, the holes 22a are positioned on the first top section leg 16a, the second top section leg 16c, the first bottom section leg 20a, and the second bottom section leg 20c. Optional holes or apertures 22a (not shown) may be included on the first middle section 18a and the second middle section leg 18c. The holes 22a may be located such that they align with corresponding holes in an adjacent guardrail 10 (i.e., in the case where one guardrail is nested with an adjacent guardrail) or with the corresponding holes in a separate splice plate (not shown in
A fastener (e.g., a nut and bolt, screw, pin etc.), passing through the holes 22a, 24a may be used to secure nested guardrails 10 to each other, to secure the guardrail(s) 10 and a splice plate (shown in
In the embodiment shown, the guardrail 10 has a corrugated geometry with a single and solid wall (i.e., no internal chambers or voids). Further, the thickness of the wall at any point in a particular cross-section of the guardrail 10 (and for substantially all cross-sectional points along the guardrail's length) is less than one inch, and in another embodiment is less than 0.5 inches, and in the embodiment shown is about 0.25 inches (See,
Referring now to
Referring now to
The above-described fiber layers or materials and the like are commercially available and are provided as examples of those fibers that may be utilized. Other types and compositions of fiber reinforcements may be used, as known to those skilled in the art, including carbon, Kevlar, etc. and the like. Fewer or more layers, as well as different compositions, of fiber reinforcements may be used. In different embodiments, the fiber reinforcement composition of the guardrail is in the range of 40-65 percent by volume, in the range of 50-60 percent by volume, and in one embodiment is about 55 percent by volume.
It should be apparent to one skilled in the art that the reinforcement layers discussed above in conjunction with
The plastic or resin materials(s) may be vinylester, epoxy, polyester, other polymer(s) and plastics and the like, or others known to persons skilled in the art. In one embodiment, urethane is utilized. Urethane may provide improved impact resistance/toughness over some others.
It should be noted that the guardrail 10 of the present invention has been certified as meeting or passing the tests, criteria or procedures set forth in the National Cooperative Highway Research Program (“NCHRP”) Report 350, by the Transportation Research Board, National Research Council, 1993, which is incorporated herein by reference. More particularly, the guardrail beam 10 of the present invention is approved for use on the National Highway System as an NCHRP Report 350 TL-3 longitudinal barrier.
Now referring to
In one embodiment, the plate or connector 50 is constructed of the same or similar pultruded composite material and manufactured in the same or similar manner as the guardrail 10. In other embodiments, the plate or connector 50 may be constructed of any suitable plastic or polymer material, such as urethane (e.g., polyurethane), vinylester, or other plastic or polymer material(s), and may include fiber reinforcing materials, and may be manufactured by any pultrusion, extrusion or injection molding, resin transfer molding or other suitable process. In yet other embodiments, the plate or connector 50 may be constructed of metal or other material.
The splice plate 50 includes a front face (i.e., facing traffic or roadway side) that substantially conforms to the shape of the back face (post side) of the guardrail(s) 10. This will allow nesting or mating of the splice plate 50 and the guardrail 10. In this manner, the splice plate 50 is placed on the back side (post side) of the guardrail(s) 10. The shape of the back face (post side) of the splice plate 50 may be different to improve performance. In another embodiment, the splice plate 50 is placed on the front side (traffic or roadway side) of the guardrail(s) 10 and therefore, the back face (i.e., facing post side) of the splice plate 50 substantially conforms to the shape of the front face of the guardrail(s) 10.
The splice plate 50 may have a plurality of holes or apertures 22b formed therein to align with corresponding holes 22a in the guardrail 10. Additionally, the splice plate 50 may have a plurality of holes or apertures 24b formed therein to align with corresponding holes 24a in the guardrails 10. In the one embodiment shown, the holes 24b are elongated (i.e., slotted) to permit slight horizontal adjustment of the splice plate 50 relative to the guardrails 10. The holes 22b and 24b may be formed by drilling or some other suitable method.
Now referring to
The posts 52, as illustrated in
As illustrated in
Now referring to
In operation 72, the reinforcement materials are combined and positioned in a pre-forming shaper or guide. In the current embodiment, the mattings and rovings are supplied in bulk on large rolls. The end of the mattings and rovings are pulled through a series of gates (or plates) each having a slot cut therein that is generally the same shape as the cross-sectional shape of the guardrail 10.
After the reinforcement materials are combined and pre-shaped in operation 72, the pre-formed materials are drawn through a resin bath and/or impregnated with a resin in operation 74, or, if a direct die injected method is utilized, operation 74 may be optional. In the current embodiment, a poly-urethane thermosetting resin is employed.
After the reinforcement materials are drawn through the resin bath and/or impregnated with the resin in operation 74, the resin-saturated reinforcements enter a heated pultrusion die in operation 76. If utilizing a direct die injection process, the resin is injected under pressure into the die. The dimensions and shape of the heated pultrusion die define the dimensions and shape of the pultruded composite guardrail 10. In the current embodiment, the amount of heat is controlled within the tolerances needed to activate the curing or polymerization of the poly-urethane resin. The applied heat causes the poly-urethane resin (and thus the guardrail) to start solidifying.
After the guardrail 10 exits the pultrusion die, the composite guardrail 10 begins to cool and solidifies even further. In operation 78, the solidified composite pultruded guardrail 10 is cut to the desired length and finished as desired. For example, the guardrail may be cut into twenty-foot lengths and holes may be formed/drilled through the guardrail such that the guardrail can be secured to a post 52 and/or coupled to another guardrail by a splice plate 50. Operational process 70 may be terminated after the guardrail is cut to length and finished in operation 78.
It should be recognized that the above-described embodiments of the invention are intended to be illustrative only. Numerous alternative embodiments may be devised by those skilled in the art without departing from the scope of the following claims.
This application claims priority under 35 USC 119(e) to U.S. provisional Application Ser. No. 60/614,355, filed on Sep. 29, 2004, and which is incorporated herein by reference.
This invention was made with government support under DOT Contract No. DTRS57-01-C-10054. The government may have certain rights in this invention.
Number | Date | Country | |
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60614355 | Sep 2004 | US |