Crash cushion and method of utilizing a crash cushion

Abstract

According to one embodiment of the invention, a crash cushion includes an energy-absorbing structure disposed between a pair of guardrails, in which each guardrail has one or more tension cables coupled between upstream and downstream ends of the guardrail. The guardrails are coupled at their upstream ends to a first support, which may be a slipbase post, and coupled at their downstream ends to a second support, which may be a vertical structure such as a utility pole.

Description

RELATED APPLICATIONS

This application claims the benefit of Ser. No. 60/512,669, entitled “Crash Cushion and Method of Utilizing Same,” filed provisionally on Oct. 20, 2003.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to the field of guardrails and, more particularly, to a crash cushion and method of utilizing a crash cushion.

BACKGROUND OF THE INVENTION

Guardrails are traffic barriers placed along roadsides to screen errant vehicles and protect their passengers from hazards behind the barrier. A common guardrail in the United States is constructed using a standard steel W-beam mounted on spaced wood or steel posts. Another type of highway safety device is the crash cushion device, which is typically utilized to protect the occupants of vehicles from injury due to impact with bridge piers, bridge rail ends, concrete barriers, or other similar objects. Highway agencies have been using crash cushion devices at dangerous locations for a number of years. These devices absorb the energy of head-on impacts with decelerations that are not life-threatening for design conditions.

SUMMARY OF THE INVENTION

According to one embodiment of the invention, a crash cushion includes an energy-absorbing structure disposed between a pair of guardrails, in which each guardrail has one or more tension cables coupled between upstream and downstream ends of the guardrail. The guardrails are coupled at their upstream ends to a first support, which may be a slipbase post, and coupled at their downstream ends to a second support, which may be a vertical structure such as a utility pole.

Embodiments of the invention provide a number of technical advantages. Embodiments of the invention may include all, some, or none of these advantages. A crash cushion according to an embodiment of the invention saves on cost and space over current methods without the necessity of extensive ground penetration in a zone of crowded underground utilities. This may be facilitated by only one point of anchorage. In addition, such a crash cushion facilitates a combination of slow energy absorption and momentum transfer to reduce initial deceleration and accommodates full kinetic energy absorption. According to another embodiment of the invention, a crash cushion uses a unique combination of mechanical energy absorption and speed reduction by momentum transfer. Such combination is designed to provide an appropriate combination of speed reduction and deceleration to effectively make occupant injuries minor or non-existent.

Other technical advantages are readily apparent to one skilled in the art from the following figures, descriptions, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the invention, and for further features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:

FIGS. 1A and 1B are plan and elevation views, respectively, of a crash cushion in accordance with one embodiment of the present invention;

FIGS. 2A through 2D are various views of a base plate and a slipbase for the crash cushion of FIG. 1 in accordance with one embodiment of the present invention;

FIGS. 3A through 3C are various views of a slipbase post for the crash cushion of FIG. 1 in accordance with one embodiment of the present invention;

FIGS. 4A through 4D are various views of a front box section for the crash cushion of FIG. 1 in accordance with one embodiment of the present invention;

FIGS. 5A through 5C are various views of a cable connection plate for the crash cushion of FIG. 1 in accordance with one embodiment of the present invention; and

FIG. 6 is an elevation view illustrating the suspension of a energy-absorbing structure for the crash cushion of FIG. 1 in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION

FIGS. 1A and 1B are plan and elevation views, respectively, of a crash cushion 100 in accordance with one embodiment of the invention. Crash cushions, which are well known in the guardrail industry, function to protect passengers of a vehicle that is headed for a dangerous rigid structure, such as an end of a concrete median barrier, when the vehicle veers off a highway, street, or road. Although the rigid structure illustrated in FIG. 1 is a utility pole 102, other rigid structures are contemplated by the present invention for use with crash cushion 100. It is believed that crash cushion 100 is the first one of its kind designed for utility poles. Although various dimensions and material types are noted in FIGS. 1A through 6, the present invention contemplates any suitable dimensions and material types for the components of crash cushion 100. In addition, although crash cushion 100 is designed to be a low-priced crash cushion that meets Level 2 requirements of NCHRP Report 350, the present invention contemplates crash cushion 100 being designed for meeting any suitable safety criteria, including Level 3 requirements. NCHRP Report 350 is herein incorporated by reference.

In the embodiment illustrated in FIGS. 1A and 1B, crash cushion 100 includes an energy-absorbing structure 104 disposed between a pair of guardrails 106a, 106b having tension cables 108a, 108b coupled between upstream ends 131 and downstream ends 133 of the guardrails 106a, 106b. Guardrails 106a, 106b are supported near upstream ends 131 by a first support 110 and coupled at downstream ends 133 to a second support, which in the illustrated embodiment is utility pole 102. Crash cushion 100 also includes an anti-side penetration device 112 coupled to upstream ends 131 of guardrails 106a, 106b, and an end cage 114 coupled to downstream ends 133 of guardrails 106a, 106b in order to couple the downstream end of crash cushion 100 to utility pole 102. This arrangement allows the entire outer frame (including guardrails, tension cables, first support, and anti-side penetration device) to slide with respect to utility pole 102 while energy-absorbing structure 104 compresses or crushes to absorb energy from a head-on impact.

In the illustrated embodiment, energy-absorbing structure 104 includes a plurality of Z-tubes, such as those described in U.S. Pat. Nos. 6,082,926 and 6,179,516, which are both herein incorporated by reference. However, energy-absorbing structure 104 may be any suitable energy-absorbing structure, such as the ET family of guardrail extruder terminals (ET-2000™, ET-PLUS™ or similar structures), barrels, fragmented concrete, Advanced Dynamic Impact Extension Modules (“ADIEMs”), or any other suitable energy-absorbing elements. The operation of the Z-tubes during a head-on collision is described in the '926 and '516 patents and, hence, will not be described here. In an embodiment where an ET-2000™ is utilized, the ET-2000™ end terminal may be rotated ninety degrees from its normal position. In this manner, when a vehicle crashes head-on into anti-side penetration device 112 the guardrail associated with the ET-2000™ is extruded vertically upward to avoid any complications with the oncoming vehicle and to allow the head of the end terminal to proceed towards utility pole 102 in an unimpeded manner as designed.

Energy-absorbing structure 104 may couple to one or more of the components of crash cushion 100 in any suitable manner. In the illustrated embodiment, the Z-tubes are suspended from the tension cables 108a, 108b, as illustrated in FIG. 6. Referring to FIG. 6, one or more cables 600 are utilized to couple Z-tubes to tension cables 108a, 108b by looping cables 600 around the barrels 602 of the Z-tubes and clamping the cables to tension cables 108a, 108b with a suitable clamping device or other suitable fastener.

Guardrails 106a, 106b are disposed on either side of energy-absorbing structure 104. In the illustrated embodiment, guardrails 106, 106b as thrie beams; however, other suitable guardrails are contemplated by the present invention, such as W-beams. In one embodiment, both guardrails 106a, 106b are slightly curved such that their concave surfaces face each other and, hence, face energy-absorbing structure 104. In this manner, cables 108a, 108b may be coupled between upstream and downstream ends of guardrails 106a, 106b, as illustrated, to form a truss-like structure. Thus, when a vehicle strikes crash cushion 100 laterally, as denoted by the directional arrow 120, the vehicle is redirected away from crash cushion 100 because cable 108b is put into tension during the collision because it is coupled to upstream and downstream ends of guardrail 106b. Therefore, the combination of guardrail 106b and cable 108b acts as a much more substantial composite beam to redirect the vehicle in a safe manner. In some embodiments, it has been found that the addition of tension cables 108a, 108b to guardrails 106a, 106b increases the bending strength by a factor of ten or more.

Guardrails 106a, 106b may couple to one or more of the components of crash cushion 100 in any suitable manner. In the illustrated embodiment, guardrails 106a, 106b are coupled at upstream ends 131 to first support 110 via a front box section 400, which is illustrated and described below in conjunction with FIGS. 4A-4D. In addition, guardrails 106a, 106b are coupled at downstream ends 133 to utility pole 102 via end cage 114. End cage 114 may also provide some vertical support to the downstream end of crash cushion 100, but provides no significant longitudinal support.

Anti-side penetration device 112 functions to prevent the penetration of the front end of crash cushion 100 into a vehicle crashing relatively sideways (e.g., at a yaw of 90°) into crash cushion 100. Any suitable anti-side penetration device is contemplated by the present invention; however, in a particular embodiment, a collision performance side impact (“CPSI”) is utilized. This CPSI is described in U.S. Pat. No. 5,791,812, which is herein incorporated by reference. In one embodiment, anti-side penetration device 112 may be coupled to front box section 400 in any suitable manner. Other suitable structures in lieu of anti-side penetration device 112 are contemplated by the present invention for use on the upstream end of crash cushion 100.

First support 110 functions to support the upstream ends 131 of guardrails 106a, 106b and front box section 400. In other embodiments, first support 110 supports energy-absorbing structure 104. In the illustrated embodiment, first support 110 is a slipbase post that is described in greater detail below in conjunction with FIGS. 3A-3C; however, the present invention contemplates any suitable support for crash cushion 100. In the illustrated embodiment, first support 110 is coupled to a base plate 122, which couples to a concrete footing 123 embedded in the ground. Concrete footing 123 may be any suitable size and shape; however, in one embodiment, concrete footing 123 is four inches thick with a length of approximately four feet and a width of approximately three feet. In other embodiments, base plate 122 is coupled to the ground directly with one or more posts, stakes 124, or other suitable anchors. In such an embodiment, the anchors are preferably short enough or oriented within the ground in a manner that avoids interference with any underground utilities.

FIGS. 2A through 2D illustrate various views of base plate 122 and a slipbase 200 for crash cushion 100 in accordance with one embodiment of the present invention. The details illustrated in FIGS. 2A through 2D illustrate one of many configurations contemplated for base plate 122 and slipbase 200 that are possible for crash cushion 100. Generally, base plate 122 includes any number of holes 202 arranged in any suitable manner to allow base plate 122 to couple to either concrete footing 123 or the ground via suitable anchors. In addition, a vertical section 204 functions to couple slipbase 200 thereto. Slipbase 200 includes a plate 206 having slots 207 that couple to respective slots 208 on vertical section 204 of base plate 122. Both slots 207 and slots 208 may have any suitable configuration. The interaction between slipbase 200 and vertical section 204 is designed to be weak in shear and strong in moment capacity. In this manner, when a vehicle strikes crash cushion 100 in a longitudinal direction (i.e., head on), then slipbase 200 is easily sheared from vertical section 204 so that energy-absorbing structure 104 can perform its function to absorb energy. Additionally, if a vehicle strikes crash cushion 100 in a lateral direction, then first support 110, which is relatively strong in moment, subjects slipbase 200 to torsion preventing it from slipping. This is described in greater detail below in conjunction with FIGS. 3A-3C.

Referring now to FIGS. 3A-3C, plan and elevation views of a slipbase post 310 are illustrated. Slipbase post 310 includes a first vertical member 300, a horizontal member 302, and a second vertical member 304. First vertical member 300, horizontal member 302, and second vertical member 304 are illustrated in FIGS. 3A-3C as being formed from circular tubes; however the present invention contemplates these components being formed from any suitable structural members. In addition, they may couple to one another in any suitable manner, such as welding.

First vertical member 300 is coupled to slipbase 200 and horizontal member 302 is coupled to first vertical member 300 and extends towards the upstream end of crash cushion 100 any suitable length. Second vertical member 304 is coupled to horizontal member 302 at a lower end thereof. Second vertical member 304 couples to front box section 400 at an upper end thereof via a vertical plate 305. In addition, second vertical member 304 couples to guardrails 106a, 106b at an upper end thereof via a vertical plate 307. Vertical plate 307 may also couple to energy-absorbing structure 104 in some embodiments.

Having slipbase post 310 in this type of configuration allows first vertical member 300 and slipbase 200 to decouple from vertical section 204 of base plate 122 during a head-on collision of a vehicle with the upstream end of crash cushion 100 (as most slipbases are designed for) while also allowing vertical member 300 and slipbase 200 to stay relatively coupled to vertical section 204 of base plate 122 as a result of a lateral force applied to crash cushion 100 by a vehicle. This lateral impact causes a torque to be applied to the slipbase connection, as denoted by reference numeral 306 in FIGS. 3A-3C, in order to keep the slipbase 200/ vertical section 204 coupling intact.

FIGS. 4A-4D illustrate various views of front box section 400 for use in crash cushion 100 in accordance with one embodiment of the invention. In one embodiment, front box section 400 is utilized to couple anti-side penetration device 112 thereto via a front plate 401. It may also be used to couple anti-side penetration device 112 to second vertical member 304 of slipbase post 310 via structural elements 402. The details illustrated in FIGS. 4A through 4D illustrate one of many configurations contemplated for front box section 400 that are possible for crash cushion 100.

FIGS. 5A-5C illustrate various views of a cable connection plate 500 for use in crash cushion 100 in accordance with one embodiment of the invention. Cable connection plate 500 illustrates one example of a component used to couple tension cables 108a, 108b to guardrails 106a, 106b. In the illustrated embodiment, cable connection plate 500 includes a first plate 501 that couples to a respective guardrail 106 via one or more bolt holes 502. First plate 501 includes one or more brackets coupled thereto for coupling the ends of tension cables 108 thereto via holes 505. Other suitable attachment methods for tension cables 108a, 108b are contemplated by the present invention.

Although example embodiments of the invention and some of their advantages are described in detail, a person skilled in the art could make various alterations, additions, and omissions without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A crash cushion, comprising:

an energy-absorbing structure disposed between a pair of guardrails;

each guardrail having one or more tension cables coupled between upstream and downstream ends of the guardrail; and

the guardrails coupled at their upstream ends to a first support and coupled at their downstream ends to a second support.

2. The crash cushion of claim 1, wherein the guardrails comprise thrie beams.

3. The crash cushion of claim 1, wherein the energy-absorbing structure comprises Z-tubes that are suspended from the tension cables.

4. The crash cushion of claim 1, wherein the energy-absorbing structure comprises a guardrail extruder terminal.

5. The crash cushion of claim 1, wherein the first support is a slipbase post.

6. The crash cushion of claim 5, wherein the slipbase post comprises:

a first vertical member coupled to a base plate;

a horizontal member coupled to the first vertical member and extending in a direction towards the upstream ends of the guardrails; and

a second vertical member coupled at a lower end to the horizontal member and coupled at a second end to the upstream ends of the guardrails, whereby the first vertical member decouples from the base plate as a result of a longitudinal force applied to the crash cushion and applies a torque to the base plate as a result of a lateral force applied to one of the guardrails.

7. The crash cushion of claim 1, wherein the second support comprises a vertical structure.

8. The crash cushion of claim 7, wherein the vertical structure is a utility pole.

9. The crash cushion of claim 1, further comprising an anti-side penetration device coupled adjacent the upstream ends of the guardrails.

10. A slipbase post, comprising:

a first vertical member coupled to a base plate embedded in the ground;

a horizontal member coupled to the first vertical member and extending toward the front end of the energy-absorbing structure; and

a second vertical member coupled at a lower end to the horizontal member and coupled at a second end to the upstream ends of the guardrails, whereby the first vertical member decouples from the base plate as a result of a longitudinal force applied to the crash cushion and applies a torque to the base plate as a result of a lateral force applied to one of the guardrails.

11. The slipbase post of claim 10, wherein the base plate is coupled to a concrete footing with one or more anchor bolts.

12. The slipbase post of claim 10, wherein the base plate is coupled to the ground with one or more posts.

13. The slipbase post of claim 10, further comprising a slipbase configured to couple the first vertical member to the base plate, the slipbase having a plurality of notched slots adapted to allow slippage as a result of the longitudinal force and prevent slippage as a result of the lateral force.

14. The slipbase post of claim 10, wherein the first vertical member, the horizontal member, and the second vertical member are formed from circular tubes.

15. The slipbase post of claim 10, further comprising a first vertical plate configured to couple the second end of the second vertical member to the upstream ends of the guardrails.

16. The slipbase post of claim 15, further comprising a second vertical plate configured to couple the second end of the second vertical member to an anti-side penetration device.

17. A crash cushion, comprising:

an energy-absorbing structure disposed between a pair of thrie beams, the thrie beams being curved such that their concave sides face each other;

each thrie beam having one or more tension cables coupled between upstream and downstream ends of the concave side of the thrie beam;

the thrie beams coupled at their upstream ends to a slipbase post and coupled at their downstream ends to a vertical structure; and

an anti-side penetration device coupled adjacent the upstream ends of the thrie beams.

18. The crash cushion of claim 17, wherein the energy-absorbing structure comprises Z-tubes that are suspended from the tension cables.

19. The crash cushion of claim 17, wherein the vertical structure comprises a utility pole.

20. The crash cushion of claim 17, wherein the slipbase post comprises:

a first vertical member coupled to a base plate;

a horizontal member coupled to the first vertical member and extending in a direction towards the anti-side penetration device; and

a second vertical member coupled at a lower end to the horizontal member and coupled at a second end to the upstream ends of the thrie beams, whereby the first vertical member decouples from the base plate as a result of a longitudinal force applied to the anti-side penetration device and applies a torque to the base plate as a result of a lateral force applied to one of the thrie beams.