Cable guardrail system and hanger

A hanger for a cable guardrail system is disclosed including a first portion with first and second seats on opposite sides of a post each seat capable of supporting a cable, and a second portion capable of engaging the end of the post. Also disclosed is a cable guardrail system including a plurality of posts, a plurality of hangers attached to at least a portion of the plurality of posts, and at least two cables supported by the seats on opposite sides of the post. The cable guardrail system may redirect an impacting vehicle and dissipate a portion of the impacting vehicle's energy.

BACKGROUND AND SUMMARY OF THE DISCLOSURE

The present invention is related to roadway barriers and safety systems, and more particularly, to cable guardrail systems.

Along many roadways it may be hazardous for a vehicle to leave the roadway. As a result, safety barriers, including guardrail systems, are used along roadways. The guardrail systems may act to contain and redirect an errant vehicle along such roadways. Such guardrail systems may dissipate some of the vehicle's energy. One such guardrail system is a cable guardrail system. Cable guardrail systems may reduce the damage caused to impacting vehicles and the injury to vehicle passengers. Compared with W-beam and three beam guardrail systems, cable guardrail systems are often more aesthetically appealing and may increase motorist sight distance. Cable guardrail systems also may reduce snow accumulation on adjacent highways and roadways.

A cable guardrail system in the past may have included a plurality of cables secured to a plurality of support posts. Various types of cables and wire ropes have been satisfactorily used for cable guardrail systems. Support posts have been made of wood, metal, or a combination of both. Additionally, cable guardrail systems have included cable anchors that fixed the end of the cables to the ground to maintain tension in the cables. Various types of anchor systems have been used including releasable anchors as described in U.S. Pat. No. 6,065,738 to Pearce.

The number of cables in prior cable guardrail systems has varied depending on factors such as the types of vehicles using the roadway and the types of hazards requiring the guardrail system. Cables have been attached to support posts using various attachment mechanisms. Some attachment mechanisms, such as hook-bolts, were used to attach a single cable to a support post. Another prior attachment mechanism attached three cables to one side of a support post as shown in U.S. Pat. Nos. 7,398,960 and 7,364,137 to Neusch. Other cable guardrail systems positioned cables on opposite sides of the support posts in order to protect against impact from either side such as might occur when the system was installed in a highway median.

The state of the art in cable guardrail systems has been documented and applied through specifications used by the industry. The United States Department of Transportation Federal Highway Administration provides “Standard Specifications for Construction of Roads and Bridges on Federal Highway Projects,” including a section for cable guardrail systems and attachment mechanisms. Industry groups such as the American Association of State Highway and Transportation Officials (AASHTO), the Associated General Contractors (AGC) of America, and the American Road & Transportation Builders Association (ARTBA) have developed “A Guide to Standardized Highway Barrier Hardware” that included specifications for cable guardrails and posts. These specifications teach a cable guardrail system having a cable attached by hook-bolts and nuts to one side of a flanged-channel post. Additionally, agencies in both the United States and Europe have established guidelines for impact testing of safety barrier systems.

Prior cable guardrail systems had several drawbacks. Some cable attachments were difficult or costly to manufacture and install. Installation of cable guardrail systems exposes installation personnel to risks associated with working on or near active highways and roadways. Cable guardrail systems have been developed that reduce installation time thereby reducing the risk faced by installation personnel. There continues to be a need, however, for cable guardrail systems that reduce installation time and cost, and reduce risk to personnel.

A hanger for a cable guardrail system capable of supporting at least two cables traverse a post is presently disclosed to dissipate a portion of an impacting vehicle's energy and enable an impacting vehicle to be redirected by the system. The cable guardrail system may be installed adjacent a roadway, such as along median strips, roadway shoulders, or any other path that is likely to encounter vehicular traffic.

The disclosed hanger comprises a first portion having first and second seats each capable of supporting a cable, with the first and second seats on opposite sides of a post, and a second portion capable of engaging the end of the post.

Additionally, the disclosed cable guardrail system may comprise a plurality of posts capable of supporting at least two cables traverse the posts, a plurality of hangers attached to at least a portion of the plurality of posts, and at least two cables supported by the first and second seats on opposite sides of the posts.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring generally toFIGS. 1 through 15, a hanger20is disclosed for a cable guardrail system10operable to dissipate a portion of an impacting vehicle's energy and redirect the vehicle. The cable guardrail system10may be installed adjacent a roadway along median strips, roadway shoulders, or at other locations likely to encounter vehicular traffic. As shown inFIG. 1, the cable guardrail system10may comprise a plurality of posts30, a plurality of hangers20attached to at least a portion of the plurality of posts30, and at least two cables11on opposite sides of the posts. As shown inFIG. 2, each hanger20may have a first portion21having first and second retaining seats22each capable of supporting a cable. Each hanger may also have a second portion25capable of engaging the end31of the post.

When the cable guardrail system10is installed along the side of a roadway, the system is capable of dissipating a portion of an impacting vehicle's energy and redirecting the impacting vehicle along the general direction of the roadway. As the vehicle impacts the cable guardrail system10, the cables11and support posts30may deflect from the installed position. The deflection of the cables11and the support posts30may dissipate a portion of the vehicle's impact energy. Additionally, forces from the vehicle impacting against the cables may cause the hanger20to move relative to the support post30. As a result, the cables11may maintain contact with the impacting vehicle dampening yaw, pitch, and roll of the impacting vehicle.

The cables11may be a 3×7 wire rope, as shown inFIG. 10. The wire rope may consist of three cords each consisting of seven strands wound together to form the cable. The diameter of each strand may be approximately three millimeters, and the diameter of the cable may be approximately nineteen millimeters. Alternately, other types of cable designs may be used. The cable11may also be pre-stressed.

The hanger20shown inFIG. 2has the first portion21and the second portion25. The first portion has first and second seats22each capable of supporting a cable adjacent a post30. When installed on the post30the first and second seats are provided on opposite sides of the post30capable of engaging cables. As shown inFIG. 2, the seats22may be formed as a rounded loop. Alternatively, the seats22may be formed as hooks, rings, or other appropriate shapes capable of supporting a cable. The seats22may fully or partially encircle the cable11. The seats22may also comprise features to secure the cable to the seat such as a latch, clasp, or similar mechanism. As shown inFIG. 2, the first portion may include a lead-in23having a shape for receiving the cable11. The lead-in23may include a friction area24providing resistance to the cable11backing out of the seat22.

The seats22may be formed in multiple ways. The seats22may be formed as an integral part of the first portion21. Alternatively, the seats22may be formed as separate pieces and attached to the first portion21, such as, but not limited to, by welding, crimping, fastening, interlocking, or another suitable attachment technique.

The second portion25of the hanger is capable of engaging the end of the post30. The second portion25may be generally U-shaped as shown inFIG. 2, so that the second portion25may slideably engage the end of the post30in a top-down installation. The U-shaped second portion25may have opposing sides or legs26, connected by an arcuate connecting portion. Other forms of the second portion25are also contemplated. For example, the second portion25may have straight or tapered sides26that are substantially parallel or angular. The sides26may taper toward each other such that the sides provide a clamping force on the end of the post. In another example, the second portion25may be shaped such that one side is substantially straight while the other side is bent, curved, or angular such as shown inFIG. 5. Various configurations of the second portion25are contemplated to adapt to various post configurations such as U-channel, I-beam, box, and other post geometries. Additionally, the length of the sides26may be selected to position the cables at the proper height relative to the top of the post30. The second portion25may include friction enhancing surface characteristics in at least a portion of the area contacting the post30such as shown inFIG. 4. Such surface characteristics may also enhance the system's ability to dissipate energy and redirect an impacting vehicle. The friction enhancing surface characteristics may include virtually all types of surface patterns, such as but not limited to a grit blast texture, scored surface, serrated surface, grit-carrying coating, or other friction enhancing surface or coating.

The first portion21and the second portion25may be formed together out of one piece of material, such as shown inFIG. 2. Alternately, the first portion21and the second portion25may be separate pieces joined together, such as, but not limited to, by welding, crimping, fastening, interlocking, or other techniques. As separate pieces, the first portion21and second portion25may be of different materials as desired.

The hanger20may be formed from steel, in the form of sheet, bar stock, tube stock, or wire stock. Alternatively, the hanger20may be formed from other metal or non-metal materials of suitable strength. The hanger may be formed from steel of spring and/or other suitable specifications. Additionally, the hanger20may have a coating to provide durability and protection against rusting in addition to engagement enhancement. The hanger20may be hot-dip coated with zinc, aluminum, zinc-aluminum alloy or other coating to provide protection against the elements. Alternately, the hanger20may be coated with a polymer or other paint coating for a protection against the environment.

Other hanger configurations are also contemplated. As shown inFIG. 6, the seats22may be positioned such that the first seat is closer to the end of the post30than the second seat. In this configuration, the sides26of the second portion25may be of different lengths. This configuration may allow the cables to be positioned at different heights relative to the ground. Alternatively, if the cable guardrail system10is installed on sloped ground the hanger ofFIG. 6may permit the cables11on opposite sides of the post30to remain at approximately the same height relative to the ground. Another hanger is shown inFIG. 7in which the first seat is laterally offset from the post30. This configuration may be useful to provide greater separation between the post and the cables.

A further alternative hanger is depicted inFIG. 8which shows a hanger20with a third seat in addition to the first and second seats. This configuration permits one cable11to be supported on one side of the post30, while two cables11are supported on the opposite side of the post. This hanger20may be useful when the cable guardrail system10is installed between hazards of different size or height, or when greater protection is required on one side of the guardrail system. Additionally, this configuration may permit cables to be placed at an appropriate height relative to the ground when the guardrail system is installed on sloped ground. A further alternative hanger is depicted inFIG. 9which shows a hanger20with a fourth seat on positioned on the opposite side of the post from the third seat. Combinations and alterations of the above hanger configurations are also contemplated that may allow a hanger20to be adapted to various posts and installation environments.

During installation or maintenance of a cable guardrail system10, the second portion25of the hanger20may slideably engage the end of the post30in a top-down installation. A first cable and a second cable may then be attached to the hanger20on opposite sides of the post. Such an installation may be faster and more efficient than installation of prior cable attachment mechanisms. Faster installations are less costly and reduce the time that installation personnel are exposed to the hazards associated with working alongside roadways. Further, maintenance of a cable guardrail system10may be improved because the hanger20may be removed and reattached.

Alternatively, a hanger20may be attached to a first cable and a second cable, then attached to a post30. The second portion25of the hanger20may then slideably engage the end of the post30in a top-down installation. By first attaching the hanger to the cables, the cables may assist in installing the hanger20over the end of the post.

As shown inFIGS. 14 and 15, a clip50may be slideably attached to the post30. The clip50may assist in securing the hanger20to the post30during installation. The clip50may also assist in preventing the hanger20from separating from the post30after installation, during maintenance, or during a vehicle impact.

The clip50may be formed from steel, in the form of sheet, bar stock, tube stock, or wire stock. Alternatively, the clip50may be formed from other metal or non-metal materials of suitable strength. The clip may be formed from steel of spring and/or other suitable specifications. Additionally, the clip50may have a coating to provide durability and protection against rusting and other environment conditions. The clip50may be hot-dip coated with zinc, aluminum, zinc-aluminum alloy or other coating to provide protection against the elements. Alternately, the clip50may be coated with a polymer or other paint coating.

As shown inFIG. 15, the clip50may be installed over the end of the post30after the hanger20has been installed. The clip50may contact the one side26of the second portion25of the hanger20. The clip50may also contact the other side26of the second portion25, or alternatively, the clip may also contact the post30. In one example, the clip50may contact both the dextral flange33and sinistral flange34of a U-channel post.

The cable guardrail system10, as shown inFIG. 1, is operable to dissipate a portion of the energy of an impacting vehicle and redirect the vehicle along the direction of the roadway. A cable guardrail system10may comprise a plurality of posts30, a plurality of hangers20attached to at least a portion of the plurality of posts30, and at least two cables11positioned on opposite sides of the posts. Additionally, a cable guardrail system10may comprise more than two cables11. Additional cables11may be supported by seats in a hanger20such as that illustrated inFIG. 8. Alternatively, additionally cables1may be supported by another cable attachment mechanism such as a hook-bolt40as shown inFIGS. 1 and 11. One embodiment may include a first hook-bolt capable of supporting a middle cable and a second hook-bolt capable of supporting a lower cable, and alternative embodiments may include some posts where all cables are supported by hook-bolts or other attachment mechanisms. The middle and lower cables may be on the same side or on opposite sides of the post30depending upon the hazards requiring installation of the cable guardrail system10.

When an errant vehicle impacts the cable guardrail system10, the post30and cables11at the point of impact may deflect from the installed position. As the defection increases, the hanger20may release from the post30so that the cables11may remain in substantial contact with the errant vehicle. Friction enhancing surfaces on the second portion25of the hanger20or on the post30may increase the energy dissipated as the hanger20separates from the post30. As the cables11release from the posts30, the overall deflection may increase. The spacing of posts30and cable anchors (not shown) may be adjusted to maintain the desired deflection of the cable guardrail system10during a vehicle impact.

As shown inFIG. 12, the post30may be generally defined as a U-channel post having a central web32and formed with a dextral flange33and a sinistral flange34such that the post30has a flanged, generally U-shaped cross-section. The post30may be of a design similar to the U-channel metal posts currently offered by Nucor Marion Steel under the RIB-BAK® trademark. For example, the U-channel post may be about 2 inches (about 51 millimeters) deep and about 3½ inches (about 89 millimeters) wide. The weight of the U-channel post may be about 5 pounds per foot (about 7.44 kilograms per meter). Although the post30may be shown as having a U-shaped cross-section, other configurations may be used as desired for a particular installation.

The support post30may be constructed of plain carbon steel having carbon content between about 0.4% and 1.0% by weight. Alternately, the plain carbon steel of the support post30may have carbon content in a range between about 0.69% and 0.75% by weight. The support post material may have yield strength between about 60,000 lbs/in2and about 100,000 lbs/in2, and a tensile strength greater than about 80,000 lbs/in2. Alternately, the support post30may have a yield strength greater than about 60,000 lbs/in2and a tensile strength greater than about 90,000 lbs/in2. The yield strength may allow the support post30to provide sufficient support to resist the vehicle impact forces associated with an impact, and may then fracture to allow more energy to be absorbed.

The support post30may have a weight between about 2 and 7 pounds per foot of post length (between about 2.9 and 10.4 kilograms per meter). Alternatively, the weight of the support post30may be about 5 pounds per foot of post length (about 7.4 kilograms per meter). Prior steel support posts typically featured a weight of 8 pounds per foot of post length (about 11.9 kilograms per meter) or greater. Although these heavier support posts may be used, the support post30of the present disclosure may reduce the weight of the support posts and the accompanying cost of the posts.

By way of example, and not limitation, the support post30may be formed from U.S. new-billet steel, rail steel, or other types of steel alloys or other materials with the desired strength for the cable guardrail system10. Further, the support post30may have a coating of polyester to provide durability and protection against rusting. Alternatively, the support post30may be hot-dip coated with zinc, aluminum, chromate, zinc-aluminum alloy or other coating to provide protection against the elements.

Installation of the support posts30may be completed using various techniques which are well known in the art. The particular technique used may depend upon the type of soil conditions and other factors associated with the roadway, and the type of road and other hazards involved in installation of the cable guardrail system10. The support posts30may be installed with or without the use of metal foundation tubes or a concrete foundation.

While the invention has been described with detailed reference to one or more embodiments, the disclosure is to be considered as illustrative and not restrictive. Modifications and alterations will occur to those skilled in the art upon a reading and understanding of this specification. It is intended to include all such modifications and alterations in so far as they come within the scope of the claims, or the equivalents thereof.