Highway Safety Device

Abstract

A highway safety device for deflecting or decelerating a vehicle as it approaches a highway hazard comprising a deformable container, the lower portion of which is filled with a low mass, collapsible core structure, and the upper portion of which contains a high-density dispersable mass, such as sand. In one form the device includes an attached or free-standing external guard rail. An impact attenuation system is also provided including the deformable container and an array of separate sacrificial containers each filled with a dispersable mass.

Description

BACKGROUND OF THE INVENTION

This invention relates to highway safety devices and more particularly to such devices for decelerating or deflecting errant vehicles as they approach an obstacle such as a bridge abutment adjacent to a highway. Recent investigations have revealed that approximately one-third of the thousands of deaths on the highways result from accidents involving only one vehicle caused by the vehicle running off the road and/or colliding with a hazardous fixed object.

There have been prior attempts to provide impact attenuating devices to be placed adjacent to such fixed highway hazards, which, upon impact, decelerate the vehicle and its occupants at rates which minimize the damage to the vehicles and reduce or eliminate injuries to the occupants.

The only such prior proposal which has been used on any substantial scale is the impact attenuating device disclosed in copending application Ser. No. 788,890 filed Jan. 3, 1969, for Energy Absorbing Deceleration Barriers. The impact attenuating device there disclosed comprises a grouping of frangible containers, usually of cylindrical configuration having in their lower portions a lightweight collapsible core structure, the upper portion of the frangible containers being filled with a dispersible mass such as sand. The frangible containers are set up in an array in front of the fixed hazard, the units being of decreasing mass in a direction away from the hazard. Actual experience has demonstrated that this type of barrier will safely decelerate a vehicle which hits the barrier at speeds up to 60 miles an hour, with minimal damage to the vehicle and minimum risk of injury to the occupants.

Despite its many advantages and its established success, the barrier disclosed in the aforesaid application Ser. No. 788,890 can not be used at all hazardous sites usually because of of deflection space limitations. Also the prior barrier has limited deflection capability. While in many cases the absence of deflection capability has a distinct advantage since it avoids redirecting the vehicle into the path of an oncoming vehicle or another vehicle moving in the same direction, nevertheless it is a disadvantage if the vehicle strikes the barrier assembly at a large angle at a point closely adjacent to the hazard.

SUMMARY OF THE INVENTION

It is the principal purpose and object of the present invention to provide improved impact attenuation devices which incorporate a substantial deflection capability as well as a substantial deceleration capability and which are adapted for installation at sites which impose severe space limitations.

It is another important object of the invention to provide improved impact attenuation devices which are particularly suited for use in combination with deceleration barriers, especially those disclosed in the aforesaid copending application Ser. No. 788,890.

It is a further object of the present invention to provide improved impact attenuation devices which require little, if any, site preparation, which are held in place primarily by their own weight and which usually require no anchoring or other structural backup, and which may be manufactured from readily available and inexpensive components.

It is also an object of the present invention to provide an impact attenuating device which is particularly well suited for sites of high impact frequency and which is capable of withstanding relatively minor impacts without sufficient damage to require repair to the barrier itself.

The barrier device of the present invention comprises primarily a sheet metal container or body, the lower portion of which is filled with a collapsible low-density core and the upper portion of which contains a dispersible mass, such as sand. The utilization of the low-density core and the high-density dispersible mass locates the center of gravity approximately at the height of the center of gravity of the impacting vehicle.

An impacting vehicle is decelerated, not only by a momentum exchange between the vehicle and the dispersible sand mass, but also by the additional forces of metal deformation and by the inertia of the metal parts themselves.

In one form, the barrier device comprises a pair of larger and smaller cylinders connected by spaced-apart metal walls or "sections" to form an enclosure, both the cylinders and the enclosure containing a sand mass. In a modified form the barrier includes an external guard rail encircling at least the forward portion of the barrier unit. The guard rail may be secured to the sheet metal walls forming the enclosure or may be free-standing, i.e., unattached to the main metal body of the barrier unit except for flexible cables which cause multiple bending of and energy dissipation by the guard rail upon severe impact.

In another form especially adapted for use adjacent to very narrow fixed objects with traffic exposure on one side only, the main body of the barrier is equipped with a guard rail on one side only.

Any of the foregoing units are capable of absorbing impacts at vehicle speeds up to about 40 miles an hour. Where higher speeds are anticipated and where space permits, the barrier unit of the present invention is preferably used in conjunction with the frangible deceleration barrier units of the aforesaid application Ser. No. 788,890.

Additional objects and advantages will become apparent as the description proceeds in connection with the accompanying drawings.

THE DRAWINGS

FIGS. 1 and 2 are, respectively, a top plan view and a side elevation of one form of highway barrier constructed in accordance with the present invention;

FIGS. 3 and 4 are, respectively, a top plan view and a side elevation of a modification of the barrier unit of FIGS. 1 and 2 incorporating an attached external guard rail;

FIG. 5 is a fragmentary enlarged section taken along line 5--5 of FIG. 3 showing details of construction;

FIGS. 6 and 7 are, respectively, a top plan view and a side elevation of a further modification of the invention including an external free-standing guard rail;

FIG. 8 is a vertical section taken along line 8--8 of FIG. 6 showing details of the guard rail and guard rail support;

FIGS. 9, 10, and 11 are top plan views of the barrier of FIGS. 6-8 as it may appear after impact;

FIGS. 12 and 13 are, respectively, a top plan view and a side elevation of a further modification of the invention particularly adapted for installation adjacent to a very narrow obstruction;

FIG. 14 is a fragmentary section taken along line 14--14 of FIG. 12; and

FIGS. 15 and 16 are, respectively, semidiagrammatic top plan views of the units of FIGS. 1 and 12 forming part of a barrier assembly including barrier units of the type disclosed in the aforesaid copending application Ser. No. 788,890.

DESCRIPTION OF PREFERRED EMBODIMENTS

Typically, the barrier unit of the present invention, indicated generally 20, is installed at the side of the highway (not shown) in position to intercept an errant vehicle as it approaches a fixed obstruction such as a bridge abutment shown partially at 22.

The principal structural components of the unit 20 are a pair of cylinders 24 and 26 connected by walls or sections 28 and 30. Preferably the cylinders 24 and 26 as well as the walls 28 and 30 are formed of corrugated sheet metal which is deformable, yet which possesses sufficient rigidity to permit fabrication to the designed shape, transportation to the site and retention of shape when loaded. For example, the cylinders 24 and 26 may be standard riveted culvert pipes of 16 gauge steel having 3 inch by 1 inch corrugations. The wall portions 28 and 30 are similarly corrugated, the corrugations in the wall portions as well as in the cylinders extending horizontally to permit nesting of the corrugations of the wall portions with the corrugations of the cylinders. Preferably, the wall portions 28 and 30 terminate at the points of contact with the cylinders and are welded, riveted, bolted or otherwise attached thereto.

In a typical case, the cylinder 24 will be 48 inches in diameter, the cylinder 26 will be 18 inches in diameter, the height of the cylinders and the wall portions will be 42 inches and the overall length of the unit will be 11 feet.

The assembled barrier unit is installed by simply placing it in the desired position. Since the unit is not anchored and is held in position primarily by its own weight, little, if any, site preparation is ordinarily required. After the unit is in position, a collapsible, lightweight, low-density core member 32 is installed at the lower end of cylinder 26. A suitably shaped similar core member 34 is also installed at the base of the enclosure formed by the wall portions 28 and 30 and the adjacent portions of the cylinders 24 and 26. A third core member 36 is also installed in the base of the cylinder 24. The assembly is completed by filling the space in the cylinders 24 and 26 and the space between the walls 28 and 30 with a dispersible mass such as sand indicated at 37. The core member may be fabricated from any number of suitable materials such as waterproof paper products, foam plastic or the like. It is essential however, that the core members be of low density and be crushable or collapsible on impact and yet possess sufficient strength in the vertical direction to support the sand mass above them. In a typical unit having the dimensions described above, the height of the core members will be approximately 1 foot. The low-density core structure has the effect of artificially elevating the center of gravity of the entire barrier unit both statically and dynamically. Preferably the center of gravity of the barrier unit is slightly above the center of gravity of the impacting vehicle. Despite wide variations in vehicle construction the center of gravity of most vehicles is approximately 21 inches above ground level. The positioning of the center of gravity of the barrier unit slightly above this level offsets the tendency of the deformable metal walls of the barrier to impart a lifting moment to the nose of the vehicle because of ground friction, etc., which would cause the vehicle to ramp over the barrier with little or no deceleration or deflection, or possibly to induce overturning.

The modified form of the invention, illustrated in FIGS. 3, 4 and 5, comprises a primary unit 20 preferably identical to the unit of FIGS. 1 and 2. In addition, the barrier unit includes an external attached guard rail assembly, comprising opposed guard rail members 40 and 42 joined at their forward ends by a terminal piece 44. The guard rail members are secured to the main body of the barrier unit slightly above the vertical midpoint thereof by a plurality of Z-shaped spacers 46. Preferably the guard rail members 40 and 42 are of W configuration and are centrally bolted to the spacers 46. The guard rail assembly also includes a straight member 47 extending across the rear of the unit tangentially of the cylinder 24 and suitably secured at its opposite ends to the ends of the guard rail members 40 and 42. The guard rail assembly is provided with rearwardly projecting extensions 48 and 49 sufficiently spaced apart to embrace the adjacent abutment 22.

The assembly is completed by a steel cable 50 extending transversely across the barrier and secured at its outer ends to gusset plates 52 and 54 carried by the guard rail members 40 and 42, respectively. The guard rail increases the deflection capability of the assembly and guards the main body of the barrier unit against nuisance damage caused by relatively light impact. The cable 50 significantly increases the performance of the unit since on direct longitudinal impact the unit will tend to assume a FIG. 8 configuration. On severe impact both of the guard rails 40 and 42 as well as the side members 28 and 30 will bow outwardly both ahead of the cable and to the rear of the cable producing a greater amount of metal deformation than would otherwise occur and thereby increasing the force available to decelerate the vehicle as desired.

The modification of the barrier unit illustrated in FIGS. 6 and 7 again includes the basic barrier unit 20 and includes an external guard rail. However, in this form of the invention the guard rail is free-standing. More specifically, the guard rail assembly comprises an inner strap 56 of one or more pieces which extends essentially around the forward portion of the barrier unit 20 and is generally of the same configuration as the barrier 20. The main guard rail members 58 and 60 are secured to the strap 56 by Z-shaped spacers 62 which extend to the ground and support the guard rail frame. The terminal piece 64 extends around the forward portion of the unit and is suitably secured to the forward ends of the guard rail members 58 and 60.

The spacer posts 62 position the guard rail assembly at the desired elevation, which is somewhat above the vertical midpoint of the barrier, and at their lower ends are secured to U-channel sheet metal skid shoes 68. The spacing between the guard rail assembly and the body of the main barrier unit 20 is, in a typical case, 1 foot along the sides of the barrier assembly and 2 feet at the front of the barrier assembly. A cable 72 extends across the barrier unit 20, the outer ends of the cable being attached to flexible cables 74 and 76 which are secured at their outer ends to gusset plates 78 and 80 carried by opposite sides of the guard rail assembly.

The assembly of FIGS. 6 and 7 is preferred for installations where space permits. The free-standing guard rail reduces the initial impact force by permitting the entire guard rail assembly to move up to 2 feet longitudinally or 1 foot laterally before contact is made with the barrier body. The cables 74 and 76 are installed with sufficient slack to permit this movement. Damage to the barrier by minor nuisance hits will be substantially reduced. Upon minor impact the guard rail frame will be displaced by sliding rather than by being deformed by compression against the sand filled body of the main barrier unit. In many instances "repair" of the unit can be effected by simply restoring the guard rail assembly to its initial position.

The barriers thus far described are high density, high G-force barriers having a deflection capability for angle impacts, which will also perform efficiently upon direct impact. They are intended for use at guard rail ends, narrow bridge abutments, piers, large poles and the like.

The selection of the appropriate barrier for use at a given site is dictated by three factors; the space available, the requirements for vehicle deflection and, the requirement for barrier damage control at sites where multiple nuisance impacts are anticipated.

The barrier of FIGS. 1 and 2, the smallest, consists of the sand container only and may be used where space (particularly width) is limited, positive deflection is not required and repeated minor "hits" are not expected. The exposed thin corrugated cylinders and walls will be deformed by light or heavy impacts from any angle.

The barrier of FIGS. 3 and 4 is some 2 ft. wider and 1 ft. longer and provides the substantial vehicle deflecting capability typical of such guard rails, increased measurably by the "back-up" or support of the sand container and its contents, against which the guard rail is mounted. Its resistance to direct or near direct impact is increased by the forces required to bend the guard rails. The cable 50 insures that each rail 40 and 42 will absorb energy by bending at the cable attachment points and at points approximately half way between the cable attachment points and both ends of the barrier on each side.

The energy of minor angle impacts will be absorbed by bending of the Z-spacers 46 without major damage to the main sand container 20, but the Z-spacers will collapse and the sand container will be damaged by major impacts from any angle.

The barrier of FIGS. 6-9 has the same qualities and operational characteristics as the barrier of FIGS. 3 and 4 except that the guard rail frame is free-standing (requiring some 2 ft. more width and 2 ft. more length), further reducing barrier damage due to minor or nuisance impacts because of the displacement of the frame by sliding on the ground surface. The slack in the cables permits the frame to move backwards until it contacts the sand container before the cables become taut and deform the sand container. The sliding movement of the guard rail frame has another advantage in that the initial barrier resistance to impact is reduced because the inertia of the frame is absorbed before the frame contacts the sand container, the principal vehicle-decelerating mass.

Reactivation after minor impacts is accomplished by dragging the frame back into its original position.

The performance of the barrier of FIGS. 6-8 in typical impact situations is illustrated in FIGS. 9, 10, and 11.

FIG. 9 illustrates the barrier as it appears after direct high-speed impact. The vehicle is decelerated by deformation of the metal components as well as by a momentum exchange between the vehicle, on the one hand, and the sand mass on the other. The cable 72 insures maximum energy absorption by metal deformation in that the guard rails are each bent forwardly of the point of cable attachment, at the point of cable attachment, and rearwardly of the cable attachment, the guard rails each thus assuming an M or W configuration, as shown in FIG. 9. The force level produced through the sand displacement will be relatively high because of the containment of sand within the metal components which must be deformed before the sand can be dispersed or displaced.

FIG. 10, illustrates the unit after low-speed impact in the region A, at an angle of about 20 degrees. It will be noted that the guard rail frame assembly is moved back toward the obstruction 22 and yet is kept in alignment by the nesting of the nose of the guard rail assembly against the front cylinder 26 and by the guiding action of the rear extensions 48 and 49. The length of the cable sections 74 and 76 is so selected as to permit this movement, without placing the cables in substantial tension. Upon an impact of this type the damage may not be sufficient to require replacement or repair of the barrier assembly, which may be reactivated by simply restoring the guard rail assembly to its original position.

FIG. 11 illustrates the barrier after a low-speed impact in the region B near the rear of the barrier at a relatively large angle. Such an impact will produce lateral displacement of the guard rail assembly into contact with the main barrier unit 20. Again the length of the cable sections 74 and 76 is sufficient to permit this type of lateral displacement of the guard rail assembly. In many cases the barrier can be reactivated after the relatively minor impact simply by restoring the guard rail assembly to its initial position. In most cases the resistance of the walls to deformation, together with the inertia of the guard rail assembly, will be sufficient to deflect the vehicle away from the obstruction 22.

In all cases the artificial elevation of the center of gravity minimizes the likelihood that the nose of the vehicle will be deflected either upwardly or downwardly causing the vehicle to ramp over the barrier or to nose down under it or to overturn.

The modified barrier unit of FIGS. 12, 13 and 14, to which detailed reference will now be made, is particularly suited for installation adjacent to very narrow fixed objects with traffic exposure on one side only. The main body of the barrier unit 84 is of essentially the same construction as the barrier unit of FIGS. 1 and 2 except that it is asymmetrical. Typically, the cylinders 86 and 88 are somewhat smaller than the previously described units, with cylinder 86 having a diameter of 30 inches and cylinder 88 having a typical diameter of 18 inches. Secured to the traffic side of the barrier body 84 is a guard rail assembly indicated generally at 90. To mount the guard rail, one wall of the barrier body 84 is provided with a reinforcing strap 92 which extends between the cylinders 86 and 88 slightly above the midpoint of the barrier body. The W-shaped main guard rail member 94 is bolted to the strap 92 and extends from a point just ahead of the forward cylinder 88 to a point substantially to the rearward of the cylinder 86. At its forward end the guard rail member supports a curved sheet metal terminal member 96. To increase the rigidity of the guard rail assembly, an outer guard rail member 98 is bolted to the inner guard rail and extends from the rearward end of the inner guard rail member to a point substantially midway between the cylinders 86 and 88. Preferably the rearwardly extending portion of the guard rail assembly is suitably secured as by bolts 100 and a mounting plate 102 fixed to the structure such as 104 which the barrier protects. Alternately, the barrier may be attached to conventional guard rail structure or to other fixed structure.

Because of the heavy guard rail construction and the anchoring of the entire assembly to the fixed structure the barrier of FIGS. 12-14 will have an unusually large deflection capability.

The barriers described herein may be used in unique combination with the deceleration barriers of Ser. No. 788,890, a typical installation of this kind being shown in FIG. 15.

As more fully disclosed in Ser. No. 788,890, the barrier units 106 comprise frangible containers which are usually of cylindrical configuration and are fabricated from a breakable plastic having a lightweight collapsible core structure and filled with sand. The barrier units 106 are sacrificial, that is they are destroyed upon impact and decelerate the vehicle by a momentum exchange between the vehicle and the dispersible sand mass. While they have proved to be unusually effective in predicably decelerating vehicles striking them at high speeds, they lose their effectiveness to a certain extent in the final stages of vehicle deceleration unless they are of extremely large mass. The use of the barrier unit such as those described in FIGS. 1 through 8, together with the barrier units 106 improves the performance of both units and tends to maintain a constant G-level of deceleration particularly in the final phase of vehicle deceleration. This combination permits a substantial reduction of the number of units 106 which are required at any given installation and accordingly reduces the overall size of the barrier system and permits it installation in sites which impose relatively severe space limitations.

The barriers of FIGS. 1 and 2 in combination with units 106 offer some deflection capability. The barriers of FIGS. 3 through 8 offer a major degree of deflection capability near the fixed object where it is usually needed, for use at those sites where a deflection capability is desired.

As shown in FIG. 16 the barrier unit of FIGS. 12-14 can also advantageously be used with a series of the barriers 106 to increase its deceleration capability.

Claims

I claim:

1. A deceleration barrier assembly adapted to be positioned adjacent to a highway hazard comprising an elongated deformable container of decreasing width from one end to the other with the wider end being positioned adjacent to said hazard and the narrower end facing an approaching vehicle, a low mass, collapsible core structure in the bottom of said container, and a high-density dispersible mass in the upper portion of said container, the density and height of said core structure being so related to the density and height of said dispersible mass to dispose the center of gravity of said barrier substantially at the level of the center of gravity of an impacting vehicle.

2. A deceleration barrier assembly adapted to be positioned adjacent to a highway hazard comprising a pair of deformable containers, a deformable wall structure connecting said containers, said wall structure including spaced-apart portions forming an enclosure with said containers positioned adjacent the opposite ends thereof, a collapsible core structure filling the bottom of said containers and said enclosure, the space above said core structure containing a dispersible high-density mass.

3. The deceleration barrier according to claim 2 wherein the opposite ends of said wall portions join said containers essentially tangentially thereof and wherein one of said containers is substantially larger than the other and said other container faces in the direction of an approaching vehicle.

4. The deceleration barrier according to claim 2 together with a guard rail extending along at least one of said wall portions externally of said enclosure in the region of the vertical midpoint of said enclosure.

5. The deceleration barrier according to claim 4 wherein said guard rail extends beyond the ends of said enclosure, one of said extending guard rail ends being free-standing and the other extending guard rail end being adapted for attachment to fixed mounting structure.

6. The deceleration barrier according to claim 2 together with a guard rail positioned externally of said enclosure in the region adjacent to the vertical midpoint of said enclosure and extending along the sides and around at least one end of said enclosure.

7. The deceleration barrier according to claim 6 together with a connector extending across said enclosure and through said wall portions for connection to opposed portions of said guard rail.

8. The deceleration barrier according to claim 2 together with a guard rail extending along said wall portions and around at least one end of said enclosure externally thereof, and means independent of said enclosure supporting said guard rail adjacent to the vertical midpoint of said enclosure.

9. The deceleration barrier according to claim 7 together with flexible connector means extending between said guard rail and said enclosure for permitting free movement of said guard rail with respect to said enclosure through a predetermined distance.

10. A deceleration barrier assembly adapted to be positioned adjacent to a highway hazard comprising an elongated deformable container of essentially uniform height from end to end and of decreasing width from one end to the other with the wider end being positioned adjacent to said hazard and the narrower end facing an approaching vehicle, a light weight collapsible core structure filling the bottom of said container and a high-density dispersable mass in the upper portion of said container, and a plurality of frangible containers positioned adjacent to the narrower end of said deformable container, each of said frangible containers having a collapsible light weight core structure at its lower end and the upper portion of each of said frangible containers containing a high-density dispersible mass.