Energy absorbing deceleration barriers

Abstract

Highway safety devices comprising an array of energy absorbing barrier units each preferably comprising a dispersible mass, effective, when struck by a vehicle, to bring the vehicle to rest at a rate of deceleration tolerable to the vehicle occupants without imposing an overturning or lifting moment on the vehicle.

What is claimed and desired to be secured by Letters Patent is: 
     
       1. Sacrificial inertial barrier apparatus for decelerating a vehicle as it approaches a hazardous area comprising at least one frangible barrier unit adapted to be positioned in the path of said vehicle in a manner to be substantially freely displaceable upon impact by said vehicle, at least the upper portion of said unit comprising a dispersible mass of predetermined density and said unit having a lower light-weight collapsible support portion, the density of said lower support portion being appreciably below said predetermined density, the mass and density of said upper portion of said unit being so related to the mass and density of said lower support portion as to dispose the center of gravity of said barrier units substantially at the level of the center of gravity of said vehicle .Iadd.when said barrier unit is in a static state prior to impact as well as during the incidence of impact .Iaddend.whereby upon impact the inertia of the dispersible mass decelerates the vehicle without imparting a substantial vertical moment to the vehicle. 
     
     
       2. The apparatus according to claim 1 wherein said units are held in position on a supporting surface solely by their weight. 
     
     
       3. The barrier apparatus according to claim 1, wherein said barrier unit is essentially cylindrical, and its axis is essentially vertical. 
     
     
       4. Apparatus for decelerating a vehicle as it approaches a hazardous area comprising a series of individual barrier units adapted to be arranged on a surface adjacent to said area, said units being freely moveable on said surface and displaceable upon impact by said vehicle, each of said units comprising a frangible container at least partially filled with a dispersible mass, the center of gravity of each of said units being disposed above its vertical midpoint, a first series of flexible connectors interconnecting the upper portions of said units, a second series of flexible connectors interconnecting the lower portions of said units, and a third series of flexible connectors interconnecting said first and second series of connectors. 
     
     
       5. The apparatus according to claim 4 wherein said units are disposed between a roadway and a fixed abutment, said units extending away from said abutment in an essentially straight line and the mass of said units progressively decreasing in a direction away from said abutment. 
     
     
       6. The apparatus according to claim 4 wherein said units are arranged in a group comprising a series of rows in front of a fixed hazard the width of said group in a direction transverse to the path of said vehicle being greater than the width of said vehicle whereby said vehicle will initially contact and displace only certain units, other of said units being progressively displaced upon movement of said vehicle into said group to thereby decelerate said vehicle at a controlled rate as it approaches said hazard. 
     
     
       7. The apparatus according to claim 4 wherein said units are arranged in a group adjacent to a fixed abutment to intercept a vehicle travelling toward the abutment, said units being of generally decreasing mass in a direction away from said abutment there being a substantial space between the unit most remote from said abutment and the next adjacent unit. 
     
     
       8. Sacrificial inertial barrier apparatus for decelerating a vehicle as it approaches a hazardous area comprising a plurality of individual frangible barrier units adapted to be positioned in the path of said vehicle in a manner to be substantially freely displaceable upon impact by said vehicle, at least the upper portion of said units comprising a dispersible mass of predetermined density and said units having a lower light-weight collapsible support portion, the density of said lower support portion being appreciably below said predetermined density, the mass and density of said upper portion of said units being so related to the mass and density of said lower support portion, as to dispose the center of gravity of said barrier units substantially at the level of the center of gravity of said vehicle .Iadd.when said barrier units are in a static state prior to impact as well as during the incidence of impact .Iaddend.whereby upon impact, the inertia of the dispersible mass decelerates the vehicle without imparting a substantial vertical moment to the vehicle, and said units being arranged in a pattern of increasing mass in the direction of movement of said vehicle. 
     
     
       9. The barrier apparatus according to claim 8 wherein said units are arranged in a group adjacent to a fixed abutment to intercept the vehicle travelling toward the abutment, the ones of said units adjacent to said abutment being closely adjacent to each other and there being a substantial space between the unit most remote from said abutment and the next adjacent unit. .Iadd. 10. The apparatus according to claim 8 wherein both the magnitude of the dispersible mass in the individual units and the number of individual units increase in said pattern in the direction toward said hazardous area with the volume of said individual units occupied by said lower support portion decrease correspondingly in the direction toward said hazardous area. .Iaddend..Iadd. 11. The apparatus according to claim 10 wherein said units are arranged in accordance with the expression ##EQU2## where: V o  = initial or original velocity, V t  = final velocity due to multiple successive impacts,   L n   -1  = "the quantity whose natural logarithm is",   Mb = mass of the barrier impacted, and   Mv = mass of an impacting vehicle. .Iaddend.