Abstract:
A collapsible crash barrier for use as and end treatment for a commonly known “Jersey Barrier” provides a frame assembly having a tubular construction and circular guides to control axial collapse of the barrier. A saddle is provided to rest upon and end section of a “Jersey Barrier” and slides along the top of a barrier when axially impacted by a vehicle in order to further control the collapse of the barrier.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation-in-part of U.S. patent application Ser. No. 09/123,309, filed Jul. 28, 1998, which issued as U.S. Pat. No. 6,082,926 on Jul. 4, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to crash cushions of the type used to arrest or slow vehicle impacts. 
     2. Description of the Related Art 
     There are some crash cushion systems that are designed to cushion vehicular impacts with the ends of portable concrete median barriers, or roadway dividers, as well as similar fixed objects. These systems include the REACT, ADIEM, Quad Guard and self-restoring Quad Guard systems. Portable concrete median dividers are placed temporarily in construction areas and the like to divide traffic. Occasionally, the dividers are left in place for an extended period of time. Unfortunately, the ends of the dividers present a deadly serious roadway hazard to vehicles which impact them. 
     If any crash protection is provided at all, it is typically provided by setting a group of plastic barrels out around the end of the divider. Sometimes the barrels are grouped together with metal banding. 
     Barrel-type barriers do not provide optimum cushioning. First, the number of barrels used is sometimes varied. As a result, too few barrels may be used to provide an effective cushion. Further, no matter how many barrels are used, this type of barrier does not provide a significant resilient redirective force against glancing impacts by vehicles. 
     Further, there continues to be a need for a low cost, reliable crash cushion which can be easily constructed from readily-available materials. Further, it is desirable to have a crash cushion which uses readily replaceable crushable portions so that the cushion can be quickly rebuilt following a collision. 
     SUMMARY OF THE INVENTION 
     A collapsible divider end treatment or crash cushion is described herein. The crash cushion is formed by a pipe rack frame that retains a number of axially disposed barrels, each of which contains crushable modules. The frame further features a slidable guide or guides which constrain the barrels and provide additional strength to the end treatment during an impact that does not proceed directly along the longitudinal axis of the barrels This allows the end treatment to substantially redirect impacting vehicles in a desirable manner. 
     In a preferred embodiment, the crash cushion employs barrels containing an energy-absorbent module that is useful for absorbing energy during a vehicular crash. The energy absorbent module provides a relatively constant and predictable level of crush resistance which makes it particularly suitable for such applications as an insert for a concrete divider or guardrail end treatment or other crash barrier. 
     The pipe rack crash cushion of the present invention provides a low cost alternative to conventional crash cushion. In addition, the pipe rack crash cushion allows the deceleration force provided by the crash cushion to be easily adjusted. Therefore, if a crash cushion is needed in special situations where the crash resistance force must be greater or lesser than that afforded by a conventional cushion, the adjustment may be easily made. The pipe rack of the present invention is also advantageous in that it can be rebuilt easily and inexpensively following a collision. 
     Thus, the present invention comprises a combination of features and advantages that enable it to overcome various problems of prior devices. The various characteristics described above, as well as other features, will be readily apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments of the invention, and by referring to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more detailed description of the preferred embodiment of the present invention, reference will now be made to the accompanying drawings, wherein: 
     FIG. 1 is a side view of an exemplary collapsible crash cushion constructed in accordance with the present invention. 
     FIG. 2 is a side view of the crash cushion depicted in FIG.  1 . 
     FIG. 3 is an isometric view of the upstream portion of the frame for the collapsible crash cushion of FIG.  1 . 
     FIG. 4 is a cutaway view of the crash cushion depicted in FIG.  1 . 
     FIG. 5 is a detail of portions of the frame and rollers of the crash cushion depicted in FIG.  1 . 
     FIG. 6 is a detail depicting an alternative roller arrangement that is useful with the frame shown in FIG.  1 . 
     FIG. 7 depicts a vehicular impact at the upstream end of the crash cushion. 
     FIGS. 8 and 9 depict exemplary barrels and crush-resistant modules that are useful in the exemplary crash cushion described herein. 
     FIGS. 10 and 11 illustrate precrushing of an end portion of a module. 
     FIGS. 12 and 13 depict a module that has been crushed along substantially all of its useful length. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 and 2 depict an exemplary end treatment  10  for a concrete divider, guardrail or other highway crash barrier. The end treatment  10  is made up of a tubular frame  12  and several axially disposed barrels  14  which are placed therein. The end treatment  10  is an exemplary device which might incorporate the crushable module as described in the present invention. The end treatment  10  is shown in FIG. 1 to be affixed to or located adjacent a concrete roadway divider  16  of a type which is well known and in place along most roadways. The treatment  10  is placed at the “upstream” end of the divider  16 . The term “upstream,” as used herein, means the general direction from which traffic, and thus impacts, are expected to approach. Conversely, the term “downstream” refers to opposite general direction. A vehicle  25  is shown in FIG. 1 approaching the end treatment  10  from an upstream end. 
     The frame  12  is preferably formed of steel or metal components which are welded to one another, although other means of affixing the components may be used. The end treatment  10  is adapted to collapse in a controlled manner when impacted from the upstream end, thus dissipating the impact energy of such an impact. A relatively uniform dissipation of energy during collapse is desirable to prevent injury to the passengers of the vehicle. 
     Construction of the frame  12  is shown in greater detail in FIGS. 3-6. The frame  12  includes a flanged runner  18  that is affixed to the ground  20 . The runner  18  has an I-beam cross section, as best shown in FIGS. 4 and 5, made up of a central web  22  and upper and lower flanges  24 ,  26  which are perpendicularly oriented to the central web  22 . The runner  18  is secured to the ground  20  using plates  28  which overlap portions of the lower flange  26  and are affixed by bolts  30  or other connectors to the ground  20 . 
     The frame  12  also includes a pipe frame rack  32  that retains barrels  14  within the frame  12 . In general, the rack  32  includes an upper longitudinal bracket assembly  34  and a lower longitudinal bracket assembly  36 . As best shown in FIG. 4, the barrels  14  are retained within the frame  12  by the upper bracket assembly  34  above and by the lower bracket assembly  36  below. 
     The rack  32  also includes a plurality of slider assemblies  38 , which slide along the length of the crash cushion  10  during an end-on impact to assist in causing a uniform crushing of the barrels  14 . The slider assemblies  38  also ensure that the bracket assemblies  32 ,  34  of the rack  32  remain disposed a relatively uniform height above the ground  20  along their length. As will be described in furter detail below, the slider assemblies  38  also assist in redirecting vehicles which impact the crash cushion  10  from a lateral side. 
     Construction of the slider assemblies  38  can be appreciated best with reference to FIGS. 3 and 4. The slider assemblies  38  are preferably constructed from pipe segments which are welded together. A central H-shaped pipe support  40  provides laterally protruding arms  42  having circular guides  44  at their ends which are shaped and sized to surround and guide portions of the upper and lower bracket assemblies  32 ,  34 , as shown in FIG.  4 . Two legs  46  extend downwardly from the central support  40 . At the lower end of each of the legs  46 , a ground-engaging skid plate  48  is affixed. The downstream side of the skid plate  48  includes an upwardly-directed flange  50 . 
     The rack  32  is affixed in sliding relation to the runner  18  by means of an assembly of rollers  52  which are designed to engage the upper flange  24  of the runner  18  in a rolling and sliding relation as the slider assemblies  38  are moved axially along the runner  18  during a vehicular impact with the end treatment  10  from the upstream direction. FIGS. 4 and 5 depict one exemplary construction for the rollers  52 . Three rollers  52  are shown. Two of the rollers engage the lower side of the upper flange  24 . The third roller  52  engages the upper side of the upper flange  24 . The rollers  52  are slidingly positioned upon sections of supporting pipe  54  and rotate about these sections. FIG. 6 shows an alternative construction for a roller  52 . In this construction, the roller  52  is rotatably secured to a hub  56  that is affixed within a supporting pipe  54 . 
     The upper and lower bracket assemblies  34 ,  36  are constructed of nested sections  58 ,  60  which permits the brackets  34 ,  36  to be collapsed in a telescoping manner. This nesting relationship is shown most clearly in FIG. 3 where it can be seen that the upstream bracket sections  58  are cross-sectionally smaller than the downstream brackets  60 . 
     A substantially U-shaped saddle  62  covers the upper portion of the concrete divider  16  and is capable of sliding along the length of the divider  16 . The downstream brackets  60  of the assemblies  34 ,  36  are welded or otherwise firmly affixed to the saddle  62 . 
     FIGS. 8-13 show an exemplary crushable module  64 , constructed in accordance with the present invention, which is used within one or more of the barrels  14  shown in FIGS. 1,  2  and  4 . Module  64  is shown constructed from a pair of materials: a stronger, structural material, such as a sheet of metal of a strength and thickness to produce a desired crush force; and a weaker, non-structural spacer material, such as polyethylene foam. The module  64  is generally cylindrical in shape and has two axial ends  66 ,  68 . The module should be appropriately sized to fit within the confines of the barrel  14 . The module  64  is formed by adjacently locating a spacing layer  70  alongside a sheet of structural material  72 . In a preferred embodiment, the spacing layer  70  comprises an air gap which is illustrated in FIGS. 8 and 9. 
     In an alternative embodiment, the layer  70  comprises a plurality of STYROFOAM® peanuts or another crushable filler. The sheet of structural material  72  comprises a metal sheet which is preferably 0.03″ 0  to 0.01″ thick aluminum or 22 to 30 gauge galvanized steel. It is pointed out that the particular thicknesses mentioned have been currently determined to be preferable thicknesses. However, the invention is not intended to be limited in this regard. 
     The layer  70  and the structural sheet  72  are wound into a cylinder in such a manner that the layer and sheet  70 ,  72  form the spiral-shaped cross-section depicted in FIG.  9 . As shown there, the winds or folds of the structural sheet  72  are separated by the spacer layer  70 . 
     Once the rolling operation is completed, a binder may be applied to maintain the module  64  in its cylindrical shape. A currently preferred binder is an adhesive bonding material or glue  73  which is applied to one end  68  of the cylinder  64  and permitted to harden, thus ensuring that the layers of the structural sheet  72  remain in a spaced relation from one another. One method of applying the glue  73  to the end  68  is to place it within the barrel  14  so that once the cylinder  64  is disposed therewithin the glue  73  will adhere to the end  68 . 
     Another currently preferred binder is a galvanized steel wire  74  of suitable thickness, such as 18 to 12 gauge. The wire  74  is attached to one axial end  66  of the module  64  and then wound in a spiral fashion around the module  64  along its length to the opposite axial end  68 . The wire  74  is affixed to the ends  66 ,  68  by securing it through small holes (not shown) which are placed into the sheet metal. This affixation is normally done prior to the precrush step explained below. Other suitable binders may be used to secure or maintain the module  64  in a generally cylindrical shape including straps and so forth. It is pointed out that the use of a wire binder may also be omitted, if desired. 
     One axial end  66  of the module  64  is precrushed to create an initial weakness in the structure of the module  64  at a desired position. FIG. 10 illustrates one method of creating the precrushed portion of the axial end  66 . As depicted in FIG. 10, the module  64  is placed into a press and an impacting member  76  is lowered onto the axial end  66  so that a precrushing load (P L ) is applied to the end  66  crushing a portion of it. If desired, portions of the end  66  may be crimped using a crimper prior to precrushing so that only the desired portion of the module  64  is crushed during the precrushing step. It is preferred that approximately one inch or so of the module  64  be precrushed in this manner. During axial precrushing or axial crushing of the module  64 , the structural sheet  72  deforms along the length of the module  64  such that the initial length (“L 1 ”) of the module  64  is reduced to a precrushed length (“L 2 ”). Following a vehicular impact, the impact force (“I F ”) causes the module  64  to be crushed to a crushed length (“L 3 ”). The presence of the spacer layer  70  provides effective voids into which the structural sheet  72  can deform, as shown in FIG.  13 . 
     It is noted that a typical module constructed in accordance with the present invention will provide crush resistance along 70-75% of its length. The crush resistance ranges from 4,000 to 30,000 pounds or more. The resistance provided by a module can be adjusted by altering the thickness of the sheet metal, the type of metal and/or the distance between the winds or folds. 
     In operation, the crash cushion, or end treatment  10 , may be impacted in a predominantly end-on fashion by a vehicle  25  approaching from the upstream direction. The upstream end of the frame brackets  32 ,  34  are contacted by the impacting vehicle as illustrated in FIG.  7 . The impact causes the upstream bracket segments  58  to be telescopically moved into the cross-sectionally larger downstream bracket segments  60 . As this occurs, the barrels  14  are crushed providing resistance to the impacting vehicle  25  and assisting in slowing and stopping it. 
     In addition to the crushing of the barrels  14 , the saddle  62  may also be slid along the length of the divider  16  during the progress of the collision. Friction between the saddle  62  and the divider  16  further resists the collision forces, also assisting in slowing and stopping the vehicle  25 . 
     The slider assemblies  38  provide for increased redirection in response to side impacts wherein the cushion is impacted in a glancing manner predominantly from a lateral side of the crash cushion  10  rather than from a predominantly end-on direction. Referring to FIG. 2, a lateral approach for a vehicle is illustrated by the arrows  80  in FIG.  2 . The sliders  38  provide cross-bracing for the pipe frame rack  32  that will stiffen it and help it withstand the collision. 
     One advantage provided by the inventive crash cushion is the adjustability of the crash resistance which results from the crushable modules used. A particular desired crush resistance can be provided by changing the crush resistance provided by the insert modules  64 . Crush resistance can be changed by, for example, using a stronger material for the structural sheet  72  or creating a tighter winding of the spiral shape for the cylinder of the module  64 . 
     Although the crash cushion  10  is shown being used for the end of a concrete divider, it should be understood that the cushion  10  would also be useful for cushioning impacts at the end of a corrugated metal guardrail or another linear median or traffic barrier. Further, the crash cushion  10  may also be modified for cushioning vehicle impacts which may occur at non-linear type obstacles such as bridge abutments, concrete underpass supports and other traffic hazards. 
     It is noted that the crash cushion of the present invention can be constructed at a lower cost and maintained at a lower cost than alternative conventional crash cushions. Currently, the market price for a system of the type described herein is expected to be around $6,000 to $8,000. In contrast, the market price for a comparable ADIEM system is around $10,000. The market price for the REACT and Quad Guard systems is around $15,000 while the self-restoring Quad Guard system cost is around $25,000. 
     While preferred embodiments of the invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit or teaching of this invention. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the system and apparatus are possible and are within the scope of the invention. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims which follow, the scope of which shall include all equivalents of the subject matter of the claims.