Abstract:
An apparatus for preventing a collision between a vehicle and an end of a Metal Beam Guide Fence. A transition device is attached to a modified section of the Metal Beam Guide Fence. The transition device and modified section are configured to allow passage of cables of a High Tension Cable Barrier through the Metal Beam Guide Fence and the transition device. The High Tension Cable Barrier redirects the colliding vehicle away from the end of the Metal Beam Guide Fence. The transition device and modified section are also configured to interact with the cables of the High Tension Cable Barrier to transfer and spread the collision load from the high tension cables to the Metal Beam Guide Fence.

Description:
PRIORITY CLAIMS 
   This application claims the benefit of priority to U.S. Provisional Application No. 60/676,926, filed on May 2, 2005, entitled “HIGH TENSION CABLE TO W-BEAM TRANSITION”, invented by John Williams, which is hereby incorporated by reference in its entirety. 
   This application also claims the benefit of priority to U.S. Provisional Application No. 60/718,886, filed on Nov. 17, 2005, entitled “HTCB-MBGF TRANSITION”, invented by John Williams, which is hereby incorporated by reference in its entirety. 

   FIELD OF THE INVENTION 
   The present invention relates to the field of protecting vehicles from roadside hazards, and more particularly to an apparatus for providing a transition from a High Tension Cable Barrier to a Metal Beam Guide Fence. 
   DESCRIPTION OF THE RELATED ART 
   A Metal Beam Guide Fence attached to a bridge abutment is designed to prevent a collision between a vehicle and the bridge abutment. A vehicle exiting a driving lane near the bridge abutment may first contact the Metal Beam Guide Fence. The Metal Beam Guide Fence then absorbs at least a portion of the energy of the impact of the vehicle and/or redirects the vehicle past the bridge abutment and back into the driving lane. In some accidents, the vehicle may impact the end of the Metal Beam Guide Fence and extensively damage the vehicle and the people within the vehicle may be injured. In other accidents, the vehicle may pass behind the Metal Beam Guide Fence with other possibly severe consequences. 
   Low tension cable barriers have been positioned prior to Metal Beam Guide Fences in an attempt to prevent vehicles from impacting the end of the Metal Beam Guide Fence. The deflections of the low tension cable barriers are large and allowed for a more gentle ridedown in areas where larger deflections can be accommodated. 
   A High Tension Cable Barrier is typically installed in a median between driving lanes to prevent vehicles from crossing the median and colliding with other oncoming vehicles. A High Tension Cable Barrier is typically not used at a bridge abutment, however, because the deflection of the High Tension Cable Barrier by an impacting vehicle may be too large and may allow the vehicle to impact off-road obstructions. In these areas, Metal Beam Guide Fence is commonly used. 
   An apparatus is desired that could be used in addition to the Metal Beam Guide Fence that would extend the protection to vehicles exiting a driving lane. 
   SUMMARY OF THE INVENTION 
   The present invention comprises a transition device attached to a modified guardrail section of a Metal Beam Guide Fence for transferring a collision load from a High Tension Cable Barrier to the Metal Beam Guide Fence. The Metal Beam Guide Fence may be attached to a roadside hazard, such as a bridge abutment. A vehicle exiting a driving lane near the roadside hazard may first contact and deflect the cables of the High Tension Cable Barrier. The High Tension Cable Barrier may redirect the vehicle away from the end of the Metal Beam Guide Fence and may transfer the vehicle and the collision load to other portions of the Metal Beam Guide Fence. A transition device attached to the Metal Beam Guide Fence may interact with the high-tension cables of the High Tension Cable Barrier to transfer the impact tension of the high-tension cables to the Metal Beam Guide Fence. In this manner, the combination of a High Tension Cable Barrier interacting with a Metal Beam Guide Fence may not only prevent a collision between the vehicle and an off-road obstruction, but may also prevent a collision between the vehicle and the end portion of the Metal Beam Guide Fence, and may prevent the vehicle from passing behind the Metal Beam Guide Fence. 
   In some embodiments of the present invention, the High Tension Cable Barrier may be in-line with a portion of the Metal Beam Guide Fence that is situated in front of an off-road obstruction. In other embodiments of the present invention, the High Tension Cable Barrier may be offset from the portion of the Metal Beam Guide Fence that is situated in front of an off-road obstruction, and instead interacts with an angled portion of the Metal Beam Guide Fence. 
   In some embodiments, the transition device comprises a plate and one or more tubes. Each of the one or more tubes may be attached to the plate. In other embodiments, the transition device further comprises one or more support members. Each of the one or more support members may be positioned between a corresponding tube and the plate and may be attached to both the corresponding tube and the plate. The attachment method may be welding. 
   The transition device may be attached to the modified guardrail section by bolts or other fasteners. The transition device may also be attached to the modified guardrail section by welding. 
   The plate may be formed into a shape to conform to the shape of a modified guardrail section such as the shape of a W-beam panel. The shape of the plate may allow the transition device to nest against the modified guardrail section. The plate may have attachment holes for bolting to the modified guardrail section and cable slots to allow passage of cables through the plate. 
   The inner diameter of the tubes may be selected to enable one or more cables of the High Tension Cable Barrier to be inserted through the tubes. The tubes may be modified with an angled cut so that the ends of cables passing through the tubes may be angled away from the modified guardrail section. The angled cut of each of the tubes may also increase the strength of the attachment of each tube to the plate. The support members may also be attached to the tubes and the plate. 
   In another embodiment, the transition device may be attached to an angled end of a guardrail section. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A better understanding of the present invention can be obtained when the following detailed description of the preferred embodiment is considered in conjunction with the following drawings, in which: 
       FIG. 1A  is a perspective illustration of a set of embodiments of an in-line transition of a High Tension Cable Barrier to a Metal Beam Guide Fence; 
       FIG. 1B  is an overhead view of the in-line transition of a High Tension Cable Barrier to a Metal Beam Guide Fence shown in  FIG. 1A ; 
       FIG. 1C  is a more detailed illustration of the in-line transition portion of the High Tension Cable Barrier to the Metal Beam Guide Fence shown in  FIG. 1B ; 
       FIG. 2A  is an overhead view of an embodiment of a transition of a High Tension Cable Barrier to a Metal Beam Guide Fence where the transition is offset; 
       FIG. 2B  is a more detailed illustration of the offset transition portion of the High Tension Cable Barrier to the Metal Beam Guide Fence shown in  FIG. 2A ; 
       FIG. 2C  is an overhead view of another embodiment of the transition of a High Tension Cable Barrier to the Metal Beam Guide Fence where the transition is offset; 
       FIG. 3A  is an illustration of an embodiment of a transition device  200 B for transferring a tension load from a High Tension Cable Barrier to a Metal Beam Guide Fence; 
       FIG. 3B  is an end view of transition device  200 B; 
       FIG. 3C  is a perspective view of transition device  200 B; and 
       FIG. 4  is another embodiment of a transition device  201  for an in-line transition of a High Tension Cable Barrier to a Metal Beam Guide Fence. 
   

   While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. 
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A High Tension Cable Barrier Coupled to a Metal Beam Guide Fence 
   In some embodiments, a High Tension Cable Barrier may be coupled to a Metal Beam Guide Fence, which may be substantially parallel to an adjacent road  199  and include a guardrail panel  197  supported by posts (e.g., support post  195 ), as shown in  FIG. 1A .  FIGS. 1A-2C  show various views of a set of embodiments of a transition device  200 A attached to a modified guardrail section  100 , of the Metal Beam Guide Fence that may transfer an impact tension load from cables  150 A-F of the High Tension Cable Barrier to the Metal Beam Guide Fence.  FIGS. 3A-C  show various views of a transition device  200 C. A typical installation of a High Tension Cable Barrier may have three cables (e.g., cables  150 A-C,  150 D-F,  150 G-I, or  150 J-L), however, a number of cables other than three is possible and contemplated. 
     FIG. 1A  is a perspective illustration of a set of embodiments of an in-line transition of a High Tension Cable Barrier to a Metal Beam Guide Fence.  FIG. 1A  shows the cables  150 A-C passing through slots  209 A-C of a modified guardrail section  100  of the Metal Beam Guide Fence. One example of a modified guardrail section  100  may be a W-beam panel modified with cable slots (such as slots  209 A-C) and mounting holes (not shown in  FIG. 1A ) for attaching the transition device  200 A. The transition device  200 A may be attached to the modified guardrail section  100  by bolts or other fasteners. In some embodiments, the transition device  200  may also be attached to the modified guardrail section  100  by welding  500 . The Metal Beam Guide Fence may be attached to a roadside hazard such as a bridge abutment (not shown in  FIG. 1A ) that would be located at the left side of  FIG. 1A . W-beam panels are produced in a variety of lengths, and any length may be selected for modification as modified guardrail section  100 . 
   A vehicle exiting a driving lane near the bridge abutment may first collide with the tensioned cables  150 A-C of the High Tension Cable Barrier. The High Tension Cable Barrier may then reduce the vehicle&#39;s speed and may transfer the impact tension load in the cables to the Metal Beam Guide Fence. In this manner, the combination of a High Tension Cable Barrier interacting with a Metal Beam Guide Fence may reduce the severity of a collision between the vehicle and a bridge abutment, but may also prevent the vehicle from passing behind the Metal Beam Guide Fence. 
   The High Tension Cable Barrier may utilize three 3×7 steel cables  150 A-C with static tension of up to 5,600 lbs. (25 KN). The cables  150 A-C of the High Tension Cable Barrier may be anchored at one or both ends into end terminals that may be restrained by end terminal posts (such as the end terminal post  120  as shown in  FIG. 2A , or  120 A,B as shown in FIGS.  2 B,C). Each of the three cables may be separately terminated at an end terminal post or a plurality of cables may be terminated at one end terminal post. 
     FIG. 1B  is an overhead view of the in-line transition of a High Tension Cable Barrier to a Metal Beam Guide Fence as shown in  FIG. 1A .  FIG. 1B  shows a transition device  200 A attached to the back of the modified guardrail section  100  of the Metal Beam Guide Fence. In some embodiments, the transition device  200 A may be attached to the modified guardrail section  100  by bolts or other fasteners. In other embodiments, the transition device  200  may be attached to the modified guardrail section  100  by welding  500 . The cables  150 A-C pass through the modified guardrail section  100  and the transition device  200 A and in some embodiments may be terminated in a cable end termination  250 B. Cables  150 A,C may also have end terminations (not shown in  FIG. 1B  since they are primarily hidden by the formed edges of the modified guardrail section  100  in this view). The static tension in cable  150 B may press the cable end termination  250 B tight against portion  210 B of the transition device  200 A. Similarly the end terminations for cables  150 A,C may also be pressed tight against the transition device  200 A. Guardrail section  105 A may overlap the modified guardrail section  100 . The portion of guardrail section  105 A that does overlap may be a straight section or a formed section. 
     FIG. 1C  is a more detailed illustration of the in-line transition portion of the High Tension Cable Barrier to a Metal Beam Guide Fence shown in  FIG. 1B . Guardrail section  105 A may also be a curved section (such as section  105 D, as shown in  FIG. 2C ). 
     FIG. 2A  is an overhead view of a set of embodiments of a transition of a High Tension Cable Barrier to a Metal Beam Guide Fence in which the High Tension Cable Barrier is not in-line with the Metal Beam Guide Fence. In these embodiments, the High Tension Cable Barrier may be offset and the cables  150 D-F may couple to the angled portion of the Metal Beam Guide Fence. Each of the cables  150 D-F of the High Tension Cable Barrier may pass through a modified guardrail section  105 C and an attached transition device  200 B and then be anchored into an end terminal (such as end terminal  250 B) restrained by an end terminal post  120 . In these embodiments, tension in the cables may transfer to the modified guardrail section  105 C due to forces on the attached transition device  200 B from the cables  150 D-F. In this manner, an impact by a vehicle against the cables of the High Tension Cable Barrier may transfer a force load to the Metal Beam Guide Fence. 
   The angle “theta 2” may be selected so that the end of the Metal Beam Guide Fence may be separated from the High Tension Cable Barrier by approximately 4′ 6″ or more. This separation may avoid a vehicle contacting the end of the Metal Beam Guide Fence as a result of deflections of the High Tension Cable Barrier. 
     FIG. 2B  is a more detailed illustration of the offset transition portion of the High Tension Cable Barrier to a Metal Beam Guide Fence shown in  FIG. 2A . Cable  150 D and  150 F may terminate at the end terminal post  120 A. Cable  150 E may terminate at the end terminal post  120 B. Cable  150 F may also terminate at a separate end terminal post (not shown in  FIG. 2B ). In these embodiments, the distance “x 1 ” may define the amount of offset of the High Tension Cable Barrier. The amount of offset may be defined as the distance between the position the cables  150 D-F may couple to the angled portion of the Metal Beam Guide Fence and the bend in the Metal Beam Guide Fence. 
     FIG. 2C  is an overhead view of another embodiment of an offset transition of a High Tension Cable Barrier to a Metal Beam Guide Fence. In this embodiment, the modified guardrail section  105 D is shown as a curved section. A transition device  200 C may be similarly curved to match the radius of the curve of modified guardrail section  105 D in such an embodiment. 
   Transition Device 
     FIGS. 3A-C  show various views of an embodiment of a transition device  200 B that may be effective in transferring an impact tension load in high tension cables from a High Tension Cable Barrier to a Metal Beam Guide Fence.  FIG. 3A  shows an edge view of the transition device  200 B comprising a plate  206  and one or more tubes  202 A-C. The one or more tubes  202 A-C may be attached to the plate  206 . In some embodiments, transition device  200 B may further comprise one or more support members  204 A-C. In these embodiments, the one or more tubes  202 A-C may be attached to both a corresponding support member and the plate  206 . The attachment method may be welding. However, a variety of other attachment methods may be used as well. 
   The plate  206  (also referred to as a nesting plate) may be a sheet of 3/16 inch thick steel, although other materials and thicknesses are contemplated. The plate  206  may be formed into a shape to conform to the shape of a modified guardrail section  100 . The shape of plate  206  may be the shape of a W-beam panel as shown in  FIG. 3B  (an end view of transition device  200 B). The shape of plate  206  may allow transition device  200 B to nest against the modified guardrail section  100 . In some embodiments, the transition device  200 B may be attached to the modified guardrail section  100  by bolts or other fasteners. In other embodiments, the transition device  200 B may be attached to the modified guardrail section  100  by welding. The plate  206  may have mounting holes  220  for bolting to the modified guardrail section  100  and cable slots  208 A-C as shown in  FIG. 3C . 
   The tubes  202 A-C may be modified sections of steel pipe. The ID of the pipe may be selected to enable a high tension cable of the High Tension Cable Barrier to be inserted through the tubes  202 A-C. A 1″ OD steel pipe may be selected. Tubes of other materials and dimensions are contemplated. The tubes  202 A-C may be modified with an angled cut from the center of one end to the side of each of the tubes  202 A-C as shown in  FIG. 3A . The angled cut may enable the tubes to be welded to the plate along the outside edge of the angled cut to increase the strength of the attachment of the tube to the plate  206 . In some embodiments, the angle of the cut may be selected so that the surface of the tube at the angled cut may contact the plate  206  when the tube is supported by a corresponding one of the support members  204 A-C. Each of the tubes  202 A-C may also be welded to a corresponding one of the support members  204 A-C in the configuration shown in  FIGS. 3A-B . 
   The support members  204 A-C (also referred to as gusset plates) may be ¼ inch thick steel plate. In some embodiments, the support members  204 A-C may be made from U shaped channels. The support members  204 A-C may be welded to the plate  206  and the tubes  202 A-C. 
     FIG. 4  shows another embodiment of a transition device  201  that may enable transfer of impact tension from cables of a High Tension Cable Barrier to a Metal Beam Guide Fence. In this embodiment, the transition device  201  may be fabricated by attaching transition device  200 A to a first end of a modified guardrail section. The guardrail section is modified with an angled cut at the first end. The angle of the cut is selected to provide a specified angle between the transition device  200 A and the modified guardrail section. In an alternate embodiment, transition device  200 A is also modified with an angled cut at the attaching end, and the angle of each cut is selected to provide a specified angle between the transition device  200 A and the modified guardrail section. The method of attachment may be by welding, however, other methods are possible and contemplated. 
   In still another embodiment of a transition device  201 , plate  206  may be replaced by a modified guardrail section with a formed end portion and one or more tubes and corresponding support members attached to the formed end portion. The formed end may have a length equivalent to the length of the plate  206 . The guardrail section may be modified with cable slots and attachment holes to bolt transition device  201  to a modified guardrail section  100 . Guardrail section  100  may be modified with cable slots and attachment holes. 
   Although the embodiments above have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.