ENERGY ABSORBING SAFETY CABLING SYSTEM

Abstract

An energy absorbing cabling system is provided to be used in place of existing cabling systems that run parallel to highways as an upgrade for safety. The system comprises a sequentially yielding cabling system that allows for increased contact time (hold time) between cables and vehicles that have lost control, thereby preventing such vehicles from breaking the cabling system and entering into dangerous areas.

Description

FIELD OF THE INVENTION

This invention relates to a system for preventing cars and the like that have lost control from leaving the road and entering into dangerous areas resulting in injury and death.

BACKGROUND OF THE INVENTION

Sections of highway bordered by areas of danger are typically protected by barriers comprising cabling supported by vertical posts. These barriers rely on the vertical posts that hold the cables but these posts can bend and break when a vehicle hits them with sufficient force resulting in the vehicle penetrating into the area of danger.

It would be advantageous to have a roadside safety cabling system with a more energy absorbing design that would increase the contact time to decelerate the vehicle, thereby reducing the risk of breaking the barrier and consequently saving lives.

SUMMARY OF THE INVENTION

According to one embodiment of the invention, there is described an energy absorbing safety cabling system. This sequentially yielding cabling system utilises cables with different modulus of elasticity. To reduce the bending moment at ground level for the vertical posts that support the horizontal cables that pass through, different spring/elasticity rates are used. The cable on the lowest horizontal position yields first. Secondly, the next higher horizontal cable yields. Thirdly, the next higher horizontal cable yields. Fourthly, the next higher horizontal cable yields last. This example is for a four-cable system but could be applied to systems with different numbers of cables.

The spacing of the vertical posts that hold the cables is further apart than current cabling systems to allow for increased hold time (contact time of vehicle and cables). The intent of this system is to not rely on the vertical posts that hold the cables in position for stopping the vehicles but the yielding of the cables to absorb the energy along with more hold time. This increased hold time allows for a slower negative acceleration, thereby reducing the force component to the cable system. Also, the larger separation distance of the vertical posts that hold the horizontal cables allows space for the cables to “catch” the vehicle as the cables yield during loss of vehicle control events. The distance between vertical posts should be able to accommodate standard vehicles. A preferable distance would be about 30 ft. Cost savings would be made with decreased vertical post spacing. Cost savings would also be made for time and materials for installations with larger vertical pole spacing.

The sequentially yielding cables from the ground up will yield at different rates (modulus of elasticity values) with greatest yield (stretch) on the lower level and the least yield on the top cable. The first point of contact for most vehicles is the bumper which is at a lower level height from the ground. Sequential variation in tension is accomplished by varying the diameter of the strands within the cables and/or by using more or less twists of strands within the cable per unit of length of cable, or by other means. Tension on the cables is determined so that cable elasticity is not exceeded during installation allowing for optimal performance of the system in absorbing energy.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described by reference to the following drawings in which:

FIG. 1 is a diagram of a section of an energy absorbing safety cabling system showing twists in cables in offset weave pattern;

FIG. 2 is a diagram of another section of the energy absorbing safety cabling system of FIG. 1;

FIG. 3 is a diagram of a cross section of a top cable in the energy absorbing safety cabling system of FIGS. 1 and 2 along the lines A-A;

FIG. 4 is a diagram of a cross section of an upper middle cable in the energy absorbing safety cabling system of FIGS. 1 and 2 along the lines B-B;

FIG. 5 is a diagram of a cross section of a lower middle cable in the energy absorbing safety cabling system of FIGS. 1 and 2 along the lines C-C;

FIG. 6 is a diagram of a cross section of a bottom cable in the energy absorbing safety cabling system of FIGS. 1 and 2 along the lines D-D;

FIG. 7 is a diagram of another section of the energy absorbing safety cabling system of FIGS. 1 and 2 showing twists in cables;

FIG. 8 is a diagram of a vertical post of the energy absorbing safety cabling system of FIG. 1;

FIG. 9 is another diagram of the vertical post of FIG. 8;

FIG. 10 is a side view of a J-Bolt attached to the vertical post of FIGS. 8 and 9.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, there is shown a diagrammatic representation of a segment of an energy absorbing safety cabling system 2 comprising two vertical posts 4 and four cables 6, 8, 10 and 12. Tension on the cables 6, 8, 10, and 12 is determined so that cable elasticity is not exceeded during installation allowing for optimal performance of the system in absorbing energy. For example, the cables 6, 8, 10, and 12 may be tensioned between the posts 4 to about 10% of the elastic limit of the cables. At the attachment points between the posts 4 and the cables 6, 8, 10, and 12, similar metals should be used to avoid galvanic corrosion.

Referring to FIGS. 3, 4, 5 and 6, there is shown a diagrammatic representation of cross sections A-A, B-B, C-C, D-D of cables 6, 8, 10 and 12 respectively showing the diameter of the strands 14 within the cables 6, 8, 10 and 12. Cable 6 has the coarsest strands resulting in the least elasticity, cable 8 has lesser coarse strands, cable 10 has even lesser coarse strands, while cable 12 has the least coarse strands and the greatest elasticity.

Referring to FIG. 7, there is shown a diagrammatic representation of a segment of the energy absorbing safety cabling system 2 illustrating the sequential variation in the twisting of cables 6, 8, 10 and 12. Cable 6 has the greatest number of twists 26 per unit length resulting in the least elasticity. The number of twists per unit length decreases through cables 8, 10 and 12 such that cable 12 has the greatest elasticity. The twists 26 in the cables 6, 8, 10, 12 may be formed in an offset weave pattern as shown in FIG. 1 or the twists 26 may extend the length of the cables 6, 8, 10, 12 as shown in FIG. 7.

Referring to FIGS. 8 and 9, there is shown a diagrammatic representation of a vertical post 4. The post comprises a boss 16 located in and sticking up from the ground 18 and a pipe 20 fitted over the boss 16. The pipe 20 can have dimensions of a schedule 40 pipe. The pipe 20 incorporates break-away slits 22 for serviceability after collision, two slits 22 are shown, but there can be six equally spaced slits 22. FIGS. 8 and 9 show a J-Bolt 24 attached to the vertical post 4 for carriage of the upper cable 6. A nylon locking nut 30 may be installed through the J-Bolt 24 and into a threaded hole 28 in the pipe 20 to connect the J-Bolt 24 to the vertical post 4 and hold torque of the J-Bolt 24 to about 30 inch-pounds. The J-Bolt 24 is torqued minimally to allow for slippage of the cable during arrest of a vehicle in a collision. The number of J-Bolts 24 will vary depending upon the number of cables; for the energy absorbing safety cabling system 2 shown in FIGS. 1 and 2, there will be four J-Bolts 24 on each of the vertical posts 4.

Referring to FIGS. 8 and 10, there is shown a cross section of a segment of a vertical post 4 with a J-Bolt 24 attached. A cross section of cable 6 is shown passing through the J-Bolt 24.

In use, when a vehicle that has lost control and left the highway contacts the energy absorbing safety cabling system, the first point of contact is likely to be the bumper which is at a lower level height from the ground. The lowest cable 12 with the greatest elasticity will yield first and then, as the vehicle comes into contact sequentially with the higher cables 10, 8, 6, the higher cables 10, 8, 6 with increasing resistance will yield sequentially, resulting in slower negative acceleration such that the vehicle can be brought to a stop before penetrating the safety cabling system.

The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

Claims

1. An energy absorbing safety cabling system comprising vertical posts in a parallel arrangement and horizontal cables in a parallel arrangement, the horizontal cables being supported by attachments to the vertical posts, wherein an elastic modulus of the horizontal cables varies sequentially from a lowest cable having a greatest elastic modulus to an uppermost cable having a least elastic modulus.

2. The energy absorbing safety cabling system of claim 1, wherein the elastic modulus of the horizontal cables is determined by a thickness of strands in an individual cable and/or a number of twists of the individual cable.

3. The energy absorbing safety cabling system of claim 1, wherein the horizontal cables number four.

4. The energy absorbing safety cabling system of claim 1, wherein a distance between the vertical posts is 30 feet.

5. The energy absorbing safety cabling system of claim 1, wherein the vertical posts are embedded in an edge of a highway.

6. Use of the energy absorbing safety cabling system of claim 1 as a safety barrier to prevent vehicles that have lost control from leaving the highway.

7. An energy absorbing safety cabling system comprising vertical posts in a parallel arrangement and horizontal cables in a parallel arrangement, the horizontal cables being supported by attachments to the vertical posts, wherein an elastic modulus of the horizontal cables varies sequentially from a lowest cable having a greatest elastic modulus to an uppermost cable having a least elastic modulus and is determined by a thickness of strands in an individual cable and/or a number of twists of the individual cable.

8. The energy absorbing safety cabling system of claim 7, wherein the horizontal cables number four.

9. The energy absorbing safety cabling system of claim 7, wherein a distance between the vertical posts is 30 feet.

10. The energy absorbing safety cabling system of claim 7, wherein the vertical posts are embedded in an edge of a highway.

11. Use of the energy absorbing safety cabling system of claim 7 as a safety barrier to prevent vehicles that have lost control from leaving the highway.

12. An energy absorbing safety cabling system comprising vertical posts spaced apart by 30 feet in a parallel arrangement and horizontal cables in a parallel arrangement between the vertical posts, the horizontal cables being supported by attachments to the vertical posts, wherein an elastic modulus of the horizontal cables varies sequentially from a lowest cable having a greatest elastic modulus to an uppermost cable having a least elastic modulus.

13. The energy absorbing safety cabling system of claim 12, wherein the elastic modulus of the horizontal cables is determined by a thickness of strands in an individual cable and/or a number of twists of the individual cable.

14. The energy absorbing safety cabling system of claim 12, wherein the horizontal cables number four.

15. The energy absorbing safety cabling system of claim 14, wherein the vertical posts are embedded in an edge of a highway.

16. Use of the energy absorbing safety cabling system 12 as a safety barrier to prevent vehicles that have lost control from leaving the highway.