Vehicle impact attenuator

Abstract

A vehicle impact attenuator includes a rail and at least one guide member moveable along the rail. At least a portion of the guide member is rotatable relative to the rail about a vertical axis by at least ±10° without binding the guide member against the rail. At least one energy absorbing element is located adjacent said guide member. A method of attenuating the impact of a vehicle is also provided.

1. A vehicle impact attenuator comprising:
 a rail comprising a side; 
 a plurality of transverse elements guided for sliding movement along the rail in a longitudinal direction, each transverse element loosely fitted to the rail such that each transverse element is free to twist about a vertical axis by at least ±10° without binding against the rail, and wherein each transverse element cooperates with said side of said rail such that each transverse element is restrained by said rail from being translated a substantial amount in a lateral direction relative thereto; and 
 a plurality of energy absorbing elements disposed between the transverse elements. 
 
     
     
       2. The invention of  claim 1  wherein each transverse element is free to twist about the vertical axis by at least ±20° without binding against the rail. 
     
     
       3. The invention of  claim 2  wherein each transverse element is free to twist about the vertical axis by at least ±25° without binding against the rail. 
     
     
       4. A vehicle impact attenuator comprising:
 a rail comprising a side; 
 at least one guide member moveable along said rail in a longitudinal direction between at least a first position and a second position, wherein at least a portion of said guide member is rotatable relative to said rail about a vertical axis by at least ±10° without binding said guide member against said rail as said guide member is moved between at least said first and second positions, and wherein said at least one guide member cooperates with said side of said rail such that said at least one guide member is restrained from translating a substantial amount in a lateral direction relative thereto; and 
 at least one energy absorbing element located adjacent said guide member. 
 
     
     
       5. The invention of  claim 4  wherein said at least one guide member comprises at least a pair of guide members spaced apart along said rail, wherein said at least one energy absorbing element is positioned between said spaced apart guide members. 
     
     
       6. The invention of  claim 4  wherein said at least one guide member comprises a transverse element coupled to said at least one energy absorbing element. 
     
     
       7. The invention of  claim 4  wherein said rail comprises opposite sides, wherein said at least one guide member comprises a pair of engagement members positioned on said opposite sides of said rail, each of said engagement members having an innermost end spaced apart from one of said opposite sides of said rail respectively such that said guide member can rotate relative to said rail. 
     
     
       8. The invention of  claim 7  wherein said rail comprises a vertically oriented central rib defining said opposite sides and a pair of horizontal flanges extending from said opposite sides of said central rib, wherein said engagement members are positioned on said opposite sides of said central rib and below said horizontal flanges, with said innermost ends of said engagement members spaced apart from said opposite sides of said central rib, and wherein said engagement members are engageable with said horizontal flanges to prevent said at least one guide member from dislodging from said rail. 
     
     
       9. The invention of  claim 4  wherein said at least one guide member is rotatable relative to said rail about said vertical axis by at least ±20° without binding against said rail. 
     
     
       10. The invention of  claim 4  wherein said at least one guide member is rotatable relative to said rail about said vertical axis by at least ±25° without binding against said rail. 
     
     
       11. The invention of  claim 4  wherein said at least one guide member extends transversely from said side of said rail. 
     
     
       12. The invention of  claim 4  wherein said at least one energy absorbing element comprises a resilient, self-restoring tube. 
     
     
       13. The invention of  claim 4  wherein said rail comprises opposite sides, wherein said at least one guide member comprises a pair of engagement members positioned on said opposite sides of said rail, each of said engagement members having an end portion facing one of said opposite sides of said rail respectively, wherein said end portions are shaped to permit rotation of said at least one guide member relative to said rail. 
     
     
       14. The invention of  claim 13  wherein said end portions each comprise a curved portion. 
     
     
       15. The invention of  claim 13  wherein said end portions each comprises at least one chamfered corner. 
     
     
       16. A method of attenuating the impact of a vehicle comprising:
 providing an impact attenuator comprising a rail having a side, at least one guide member moveably coupled to said rail, and at least one energy absorbing element located adjacent said guide member; 
 impacting said impact attenuator with said vehicle; 
 moving said guide member along said rail in a longitudinal direction in response to said impacting said impact attenuator with said vehicle; and 
 rotating at least a portion of said guide member relative to said rail about a vertical axis by at least 10° without binding said guide member against said rail as said guide member is moved along said rail in said longitudinal direction; and 
 engaging said side of said rail with said at least one guide member and thereby preventing said guide member from translating a substantial amount in a lateral direction relative to said rail. 
 
     
     
       17. The method of  claim 16  wherein said at least one guide member comprises at least a pair of guide members spaced apart along said rail, and wherein said at least one energy absorbing element is positioned between said spaced apart guide members. 
     
     
       18. The method of  claim 16  wherein said at least one guide member comprises a transverse element coupled to said at least one energy absorbing element. 
     
     
       19. The method of  claim 16  wherein said guide member comprises a pair of engagement members positioned on opposite sides of said rail, each of said engagement members having an innermost end spaced apart from said rail, wherein said rotating said guide member relative to said rail comprises moving said innermost ends toward said rail. 
     
     
       20. The method of  claim 19  wherein said rail comprises a vertically oriented central rib and a pair of horizontal flanges extending from opposite sides of said central rib, wherein said engagement members are positioned on opposite sides of said central rib and below said horizontal flanges, with said innermost ends of said engagement members spaced apart from said central rib, and wherein said engagement members are engageable with said horizontal flanges to prevent said guide member from dislodging from said rail. 
     
     
       21. The method of  claim 16  wherein said rotating said at least said portion of said guide member relative to said rail about said vertical axis comprises rotating said at least said portion of said guide member relative to said rail about said vertical axis by at least 20° without binding against said rail. 
     
     
       22. The method of  claim 16  wherein said rotating said at least said portion of said guide member relative to said rail about said vertical axis comprises rotating said at least said portion of said guide member relative to said rail about said vertical axis by at least 25° without binding against said rail. 
     
     
       23. The method of  claim 16  wherein said guide member extends transversely from opposite sides of said rail. 
     
     
       24. The method of  claim 16  wherein said at least one energy absorbing element comprises a resilient, self-restoring tube. 
     
     
       25. The method of  claim 16  wherein said impacting said impact attenuator with said vehicle comprises impacting said energy absorbing element with said vehicle. 
     
     
       26. The invention of  claim 1  wherein said side is substantially vertical. 
     
     
       27. The invention of  claim 4  wherein said side is substantially vertical. 
     
     
       28. The invention of  claim 16  wherein said side is substantially vertical. 
     
     
       29. A roadway crash cushion, comprising:
 an array of collapsible cells, each cell having an arch in at least opposite portions of the cell;   a plurality of guides disposed between the collapsible cells and coupled to the arches on the opposite portions of the cells, wherein the cells extend laterally outwardly from the guides coupled thereto such that the cells are positioned to transfer a lateral impact load applied by a vehicle to the guides; and   wherein each guide is guided for sliding along a longitudinal rail member extending along a center longitudinal axis of the crash cushion as the collapsible cells collapse, and wherein each guide cooperates with a side of the rail member such that the guide is restrained by the rail member from being translated in a lateral direction relative thereto.    
     
     
       30. The roadway crash cushion of claim 29, wherein the cells comprise an elastomeric material.  
     
     
       31. The roadway crash cushion of claim 29, wherein the cells comprise a polyethylene material.  
     
     
       32. A roadway crash cushion, comprising:
 a pair of diaphragms each extending transversely relative to a longitudinal axis along which the roadway crash cushion collapses, the pair of diaphragms moveable relative to each other during an axial impact along the longitudinal axis;   a pair of energy absorbing elements disposed between the pair of diaphragms, each of the energy absorbing elements having an arch, wherein the pair of energy absorbing elements extend laterally outwardly from the pair of diaphragms; and   wherein each diaphragm is guided for sliding along a longitudinal rail member extending along a center longitudinal axis of the crash cushion as the collapsible energy absorbing elements collapse, and wherein each diaphragm cooperates with a side of the rail member such that the diaphragm is restrained by the rail member from being translated in a lateral direction relative thereto.    
     
     
       33. The roadway crash cushion of claim 32 wherein the diaphragms each comprise a rectangular member.  
     
     
       34. The roadway crash cushion of claim 32 wherein the energy absorbing elements each comprise an elastomeric material.  
     
     
       35. The roadway crash cushion of claim 32, wherein the energy absorbing elements each comprise a polyethylene material.  
     
     
       36. The roadway crash cushion of claim 32, wherein the energy absorbing elements flatten along the longitudinal axis when collapsing.  
     
     
       37. A roadway crash cushion, comprising:
 a collapsible, substantially self-restoring portion comprising a plurality of energy absorbing elements each comprising a camber and formed substantially of a resilient polymeric material;   a plurality of guides, each of said guides disposed between, and secured to the cambers of, an adjacent pair of energy absorbing elements, wherein the adjacent pairs of energy absorbing elements extend laterally outwardly from the respective guides such that the energy absorbing elements are positioned to transfer a lateral impact load applied by a vehicle to the guides; and   a longitudinal, ground-mounted rail member extending along a center axis of the crash cushion and having a side, wherein the guides cooperate with the side of the rail such that the guides are restrained by the rail from being translated in a lateral direction relative thereto.    
     
     
       38. The roadway crash cushion of claim 37, wherein the resilient polymeric material comprises polyethylene.  
     
     
       39. The roadway crash cushion of claim 37, wherein the camber provides for the energy absorbing element to become elongated transverse to a longitudinal axis and flattened along the longitudinal axis.  
     
     
       40. The roadway crash cushion of claim 37, wherein the guide comprises a laterally extending plate member disposed under an elevated surface of the rail.  
     
     
       41. The roadway crash cushion of claim 37 wherein the guides are secured to the energy absorbing elements with bolts passing through holes in the energy absorbing elements.