Patent Publication Number: US-3876185-A

Title: Vehicle energy absorbing device

Description:
United States Patent 91 Welch 1451 Apr. 8, 1975 1 1 VEHICLE ENERGY ABSORBING DEVICE [21] Appl. No.: 347,328  
 [52] US. Cl. 256/1; 256/131; 404/6 [51] Int. Cl ..E0lf 13/00 [58] Field of Search 256/1, 13.1; ll4/219;  
 [56] References Cited UNITED STATES PATENTS 2,562,957 8/1951 Sipkin et a1 114/219 3,148,477 9/1964 Bjorn et a1. 52/591 3.292.331 12/1966 Sums 52/309 X 3.353.812 ll/1967 Miller ll4/219X 3.426.542 2/1969 Hindman et a1. 114/219 X 3,503,600 3/1970 Rich 256/1 X 3.563.525 2/1971 Narabu 267/140 3,606,258 9/1971 Fitch 256/131 3,614,148 10/1971 Favary 267/139 X 3,695,583 10/1972 Walker et a1. 256/1 3.721.433 3/1973 Sobel 267/140 FOREIGN PATENTS OR APPLICATIONS 856,648 3/1940 France [14/219 Primary E.\&#39;aminerDennis L. Taylor Attorney, Agent, or F irmTrask &amp; Britt [57 ABSTRACT Highway safety devices placed adjacent a highway obstacle comprising a number of discrete resilient units which interconnect to form a continuous resilient energy absorbing highway barrier capable of safely decelerating a colliding motor vehicle are disclosed. Shaped, resilient, foamed plastic units are assembled to form a highway obstacle barrier capable of absorbing a vehicles momentum with minimum damage to the vehicle and little injury to its occupants.  
 9 Claims, 8 Drawing Figures PATENTEDAFR 1% SHEET 2 BF 2 VEHICLE ENERGY ABSORBING DEVICE BACKGROUND OF THE INVENTION The present invention relates to highway safety devices. Particularly, the present invention relates to devices for the prevention of collisions between moving motor vehicles and immovable highway obstructions, such as bridge abutements, by controlled deceleration of the moving motor vehicle.  
  Most current highway safety devices, such as the familiar guard rail, are tangent deflection devices designed to deflect vehicles striking the device. These devices do not perform the function of a head-on type of highway safety barrier for when they are struck by a vehicle at a high angle incident to the barrier the re sults are often as severe as a collision with the obstruction which the device was guarding.  
  The prior art includes several patents for highway safety guards. The Bianchi device, U.S. Pat. No. 3,292,909, consists of sheaves mounted on vertical end supports. The sheaves rotate freely about the vertical axes. Cables are drawn through the sheaves and these cables act as both an absorbent and a deflective barrier for the colliding vehicle by elastic deformation. The Schimmelpenninck device, U.S. Pat. No. 3,288,440, is an open, continuous, resilient trough filled with sand which is designed to deflect the colliding motor vehicle and partially absorb the energy of collision. A third type of guard is the Fitch invention, U.S. Pat. No. 3,606,258, which consists of an array of energy absorbing barrier units each preferably comprising a dispersible mass. The barrier is typically comprised of destructable sand filled barrels. A vehicle is decelerated through intermittant consecutive collisions with these barrels.  
  The instant invention is unique and novel being&#39;neither related to nor taught by the prior act. Among its many advantages is the fact that it is not a deflective barrier as are the Bianchi and Schimmelpenninick devices, but is designed to absorb the full impact of the colliding motor vehicle. The instant invention entraps a colliding vehicle, preventing it from deflecting off the barrier into other objects or into the path of traffic. The instant device can absorb the collision of vehicles from a wider range of directions than is possible with prior guards such as the Fitch device. The instant invention is a reuseable barrier whose components do not have to be replaced after every collision with a motor vehicle as is the case with the Fitch invention.  
  This invention also relates to truck runaway lanes used to stop runaway trucks coming off steep hills. Conventional truck runaway lanes generally consist of a stretch of inclined roadway adjacent to the main highway. Generally, a considerable length of inclined road is needed to stop a runaway truck. Often the necessary space for such a truck runaway lane is not available adjacent to a highway. The instant invention relates to a type of truck runaway barrier which absorbs the collision of a runaway truck and stops the truck in a much shorter distance than is possible with conventional truck runaway lanes. This instant invention allows truck runaway lanes to be placed in areas too small for conventional truck runaway lanes.&#34;  
 OBJECTS OF THE INVENTION Accordingly it is the principal object of the present invention to provide an improved resilient highway safety barrier which is capable of decelerating motor vehicles striking the barrier head-on with a minimum of damage to the occupants of the motor vehicle and the motor vehicle itself.  
  It is a further object of the present invention to provide a resilient highway safety barrier of novel construction capable of absorbing the impact of a moving motor vehicle; said barrier being of a construction which permits repeated collisions without substantial destruction to the barrier, being easy to construct, and being sufficiently flexible in design to be modified to varying construction site conditions.  
 SUMMARY OF THE INVENTION To attain these objects the present invention provides a resilient highway barrier comprising a mass of discrete, flexible units. Preferably the units are of a resilient, weather-resistant, polymeric material, e.g., silicone, rubber, or plastic foam. The units are secured to adjacent units and preferably to the ground by connecting means. The individual units are of a size and shape permitting ease in construction of the barrier. The typical individual unit being a cube having an edge dimension about one-half feet to about 3 feet in length and having connecting means which allow the units to form a continuous resilient barrier of a size and shape to meet conditions surrounding the obstacle. The resilient truck runaway lane barrier is constructed of similar resilient units at the end of a short truck runaway lane.&#34; The size and shape of the individual units will be described in greater detail below.  
 DESCRIPTION OF DRAWINGS FIG. 1 is a diagrammatic top view of the barrier in accordance with the invention shown in its normal installed configuration. 7  
 FIG. 2 is a diagrammatic elevational view of the barrier in accordance with the invention shown in its normal installed configuration.  
  FIG. 3 is a perspective view of a barrier unit illustrating one type of tongue and groove interconnecting means.  
  FIG. 3a is a bottom perspective view of a barrier unit illustrating another type of tongue and groove interconnecting means.  
  FIG. 4 is a perspective view of a group of barrier units interconnected by means of a line drawn through a hole formed in the unit to adjacent similar units.  
  FIG. 5 is a perspective view of a barrier in which each horizontal row of units overhang the horizontal row of units immediately below it forming a trap for a colliding motor vehicle.  
  FIG. 6 is a diagrammatic top view of the truck runaway lane barrier shown in its normal installed configuration.  
  FIG. 7 is a diagrammatic elevational view of the truck runaway lane barrier shown in its normal installed configuration.  
 DESCRIPTION OF PREFERRED EMBODIMENT Referring now more particularly to the drawings the resilient barrier system of the present invention is illustrated in FIG. 1 and FIG. 2 in a typical configuration,  
 i.e., adjacent a highway 20 inposition to intercept and decelerate a vehicle 21 traveling toward a fixed obstruction 22. The resilient barrier system 23 is comprised of a series of individual units 24 which will be described in detail hereinafter. The arrangement of the individual units into barriers can be varied to meet the conditions surrounding a particular obstruction. The barrier illustrated in FIG. 1 partially surrounds the obstacle. The preferred length, height and width of such a barrier is set forth hereinafter.  
  The individual unit may take on a variety of forms and may be constructed in varying sizes. The preferred Yield stress (p.s.i.)  
 individual unit 24 is a resilient cube or block comprised of a resilient material. Useful materials include natural rubber, synthetic rubbers, polyurethanes, polysiloxanes, (silicones) and similar polymeric materials which can be processed to form resilient blocks of various densities, resiliencies and if a foam product is utilized, cell configurations. Polyurethane and silicone resins are particularly useful since a wide variety of products with various desired characteristics can be formed. Foamed products having various resiliencies and densities, e.g., densities from about 5 to about 50 pounds per cubic foot, may be obtained readily. The blocks are preferably foamed plastics having a preferred density of about to about 40 pounds per cubic foot.  
  The units of the present invention should be weather resistant, i.e., be resistant to degradation by water and ultraviolet light. The units should be of a size, shape and weight that can be easily handled by one man. Therefore, the volume and density of the units are interrelated. The units preferably have an individual weight of about 30 to about 70 pounds. The desired density is also a function of the mass and depth of a particular barrier.  
  The distance required to safely stop a motor vehicle is independent of the decelerating means and the size of the vehicle. The limiting factor is the magnitude of the deceleration which passengers can safely withstand. A value of 12 to 15 gs is a reasonable estimate of the upper limit of the magnitude of the deceleration which passengers can withstand for short time periods.  
  The important parameters for the barrier are (l the force that it will exert on a vehicle colliding into it, (2) the amount of deformation it will sustain before its resistance to further deformation becomes excessively large, and (3) whether the deformation is plastic or elastic. If the barrier material deforms in an elastic mode, the vehicle will rebound from the barrier at a speed approximating the initial velocity. This would create a traffic hazard as the vehicle rebounded into the flow of traffic. If the material deforms plasticly then&#39; the vehicle will come to rest with no rebound.  
  Assuming a plastic deformation and accepting a maximum deceleration of 15 g&#39;s the deformation (D) will D velocity of vehicle in ft/sec) /(32.2 ft/sec )(gravitational force) The length (L) of the barrier which would give the required plastic deformation is given by L 2D for a 50 percent planned deformation of the barrier material.  
  For example, the displacement of a vehicle traveling at 60 miles per hour would be The necessary yield stress (psi) of the barrier material will be dependent on the mass of the automobile, the displacement (D) of the barrier and the velocity at which the vehicle strikes the barrier.  
 (weight of vehicle in lbs.). (velocity of vehicle in ft./sec.)  
 (64.4 ft./sec. (cross-sectional-area of vehicle in ft. (displacement (144 inP/ft?) in ft.)  
  The front end of a vehicle weighing approximately 5,000 pounds is 7.5 to 12.5 square feet. Therefore, the yield stress of the material for the above conditions should be between about 20.9 psi and about 35.8 psi. The material can be formulated to give this yield stress.  
  The weatherability of the resilient units may be improved by encapsulating the blocks in a thin adherent flexible film of plastic material, i.e., polyethylene, polypropylene, polyvinyl resins such as polyvinyl chloride, polyvinyl acetate and the like. Conventional adhesives can readily adhere a plastic protective film to the unit. Also, polyurethane units will easily adhere to a flexible protective outer film by lining the unit mold with the external film and placing a foamable polyurethane resin in the interior. The polyurethane resin expands as it foams, filling the entire mold and adhering itself to the flexible film. Before use in a barrier the units may be cored to increase their resiliency.  
  In order to form an effective continuous resilient barrier it is necessary that the units be joined together by connecting means. The connecting means may be formed into the individual unit itself by shaping the sides of the individual unit 24 into a tongue and groove configuration, as shown in FIGS. 3 and 3a, so that the individual unit interconnects with adjacent units. A typical tongue and groove interconnecting means shown in FIG. 3 consists of a square tongue 25 which securely fits into a square groove 26 of an adjacent unit. The exact shape and size of the tongue and groove configuration may vary. One of the many alternative shapes is shown in FIG. 3a. In the tongue and groove shown in FIG. 3a the end of the tongue 27 is wider than the portion of the tongue 28 immediately connected to the main body of the unit 24. The groove is shaped to securely interconnect with the tongue; the portion of the groove 29 immediately adjacent the main body of the unit 24 being wider than the outer portion of the groove 30. This shape securely connects adjacent units together. There are many types of tongue and groove shaped in various triangular configurations. FIGS. 3  
 and 3a show only two of the wide variety of tongue and groove means available. Interconnecting configuration formed into the unit can be placed on any of the surfaces of a unit so that the unit can interconnect with any desired adjacent unit.  
  Another connecting means involves forming holes through each unit 24. The number and position of the holes in the unit can be varied to meet a variety of interconnecting means/FIG. 5 shows one type of interconnecting means. In FIG. 5 strong lines 32, i.e., wires,  
 ropes, or chains, are drawn through the horizontal hole 31 of each unit in a row of units and looped at the end of each row and drawn through the horizontal hole of an ajdacent row of units. This process is continued until each row is interwoven or tied securely to adjacent horizontal and vertical rows of units in the barrier.  
  Another type of interconnecting lines are rods made of a resilient material. Said rods are placed through horizontal, lateral, and vertical holes formed in aunit. Thus, the rods interconnect the individual units with adjacent horizontal and vertical units forming a continuous resilient barrier.  
  By the use of interconnecting means, such as those described above, it is possible not only to form the units into one continuous barrier but it is also possible to form the units into one barrier comprised of a number of separate independent adjacent barriers. This configuration would permit greater flexibility of the barrier as a whole, since these individual barriers can move independently of one another.  
  A means for securing the units to the ground while retaining a degree of freedom for horizontal movement is shown in FIG. 5. A strong line 33, i.e., a wire, rope, or chain, can be used to attach the units securely to the ground by drawing said line through the horizontal holes 35 of the rows of the units immediately adjacent the ground and securely attaching said line to a metal hook means 35 securely driven into the ground. Said line 33 securing the barrier to the ground runs parallel to the direction of the expected impact of a colliding vehicle so that the units through which the line 33 is placed may freely move along the line upon contact with a colliding vehicle. This process forms a continuous resilient barrier, secured to the ground, capable of a degree of horizontal movement.  
  Another means for securing the barrier to the ground while retaining a degree of freedom for horizontal movement is to form longitudinal T-shaped slots into the bottom of each individual unit adjacent to the ground which fit upon elongated T-shaped rails. The T-shape rails have a cross-sectional shape similar to railroad rails. The T-shaped rails are securely attached to the ground. The T-shaped tracks are placed parallel to the expected direction of impact of a colliding vehicle. Thus, the units may freely move along the rail upon impact with a colliding motor vehicle. The individual units are secured to adjacent units by connecting means described above.  
  Often vehicles colliding head-on into a barrier will vault&#34; over the barrier and crash into the obstruction. To prevent this occurence a properly constructed barrier can capture the vehicle and prevent it from vaulting&#34; over the barrier. A typical barrier trap is illustrated in FIG. 5. In this barrier each horizontal row of units 36 extend beyond the horizontal rows of units immediately beneath it. A cave 37 is formed by the overhanging horizontal rows of units. This cave effectively traps a colliding vehicle and prevents the vehicle from vaulting over the barrier. The cave is perpendicular to the direction of expected impact.  
  A typical barrier 23, illustrated in FIG. 1 adjacent a highway obstacle 22 about 2 feet in diameter, is about 3 to about 8 feet in height, preferably from about 6 to about 12 feet wide and over 32 feet deep. Individual units are preferably about two to about 8 cubic feet in volume. The units are interconnected as described above. The barrier may have a total weight of about 2,000 pounds to about l00,000&#34;pounds although the total preferable weight is about 10,000 to about 50,000 pounds. In an inelastic collisibr&#39;itlfereductionofthe vehicles speed is &#39;the ratio of the weight of the barrier to the vehicle. From this relationship the following eq&#39;uation is derived V,-/V antiln. M f M,..  
 Where g l I V,- initial velocity V final velocity M,, mass of the barrier M, mass&#39;of the vehicle Using this equation it is calculated that a barrier weighing approximately 12,000 pounds will slow &#39;a 5,000 pound car from 60 miles per hour to 5 miler p er&#39;hour.  
  The truck runaway lane barrier as shown inEIG S. 6 and 7 is constructed of individual units described above. The individual units are interconnected and S67 cured to the ground by means described aboves The barrier can be in the form of a U-shaped crescent and is placed at the end ofa truck runaway lane 38 which is paved with deep sand to slow the runaway truck down before it engages the barrier 39. The length of the truck runaway lane will vary with topographical conditions. The barrier is designed for situations where the length of the inclined runaway lane is not sufficient to completely slow down the runaway truck. The exact dimensions and weight of the trap will depend on the length of the runaway lane, the expected mass and the speed of the typical runaway truck.  
  Using the above equation for calculating the barrier mass it is calculated that it takes a total barrier weight of 400,000 pounds to decelerate an 80 ton truck from 60 miles per hour to 5 miles per hour. The calculated yield stress is about 340 psi for a truck with a crosssectional area of 25 square feet and a barrier depth of 32 feet.  
  The main portion of such a barrier 40 would have a total width of about 40 feet to about 80 feet with an inner lane impact area 41 of about 30 feet to about 70 &#39;feet wide, a length of about 32 feet to about feet and a height of about 8 feet to about 12 feet at the main impact area 40. The inner lane impact area 41 can be gradually narrowed to form a trap for the runaway truck. The walls 42 of the typical barrier are about 4 feet to about 7 feet wide with a total length of about 30 feet to about 60 feet depending on the area available for the barrier. The height of the wall 42 is about 8 feet to about 12 feet. The resilient portion of the barrier is backed by an earth embankment 43 which is about 7 feet to about 10 feet high, about 15 feet to about 25 feet deep and about 60 feet to about feet wide. The earth embankment also extends behind both walls of the barrier. This extension 44 is about 4 feet to about 7 feet wide, about 7 feet to about 10 feet high and runs the entire length of the barrier wall 42. The purpose of the walls 42 of the barrier is to direct the runaway truck into the main impact area as well as absorb the impact of the runaway truck. The length of the truck runaway lane will depend on the area available to build the barrier.  
  The invention described herein has been primarily described with reference to impact barriers to reduce injuries in head-on type collisions. The novel devices of this invention can, however, also serve as tangent deflectiondevices to. prevent damage to vehicles and injuryto&#39;passengers; Although the invention has been described hereunder by reference to {particular embodiments, it is not,  
 intended to be limited solely thereto, but to include all the variations and modifications falling within the scope of the appended claims.  
 I claim:  
  1. A reuseable resilient highway safety barrier comprised of a mass of discrete independent resilient plastic blocks having interconnecting means to connect said blocks with one another and in contact with a highway obstacle for decelerating motor vehicles which would collide with the obstacle except for the presence of ,said barrier, said plastic blocks being stacked and having interconnecting means to connect said barrier to the ground.  
  2. The barrier of claim 1 wherein the discrete independent resilient blocks are square framed plastic blockswe&#39;ighting about 30 to 70 pounds.  
  3. The barrier of claim 1 wherein the independent resilient blocks are comprised of a flexible, weatherresis&#39;tant, polymeric foam material having a density of about 10 to about 40 pounds per cubic foot.  
  4. The barrier of claim 1 wherein the resilient blocks form a continuous resilient barrier about three to about eight feet high.  
 5. The barrier of claim 4 wherein the connecting 7. The barrier of claim 1 wherein the connectin means for connecting the barrier to the ground are lines drawn through holes in the resilient units, said lines being secured to hook means secured to the ground.  
 8. A barrier of claim 1 wherein the barrier is supported to the rear and sides by an earthen embank -i ment.  
  9. The barrier of claim 4 wherein the total barrier V weight is from about 10 thousand to about 50 thousand pounds.