Road structure – process – or apparatus – Traffic steering device or barrier
Reexamination Certificate
1999-09-23
2001-09-18
Shackelford, H. (Department: 3673)
Road structure, process, or apparatus
Traffic steering device or barrier
C256S013100
Reexamination Certificate
active
06290427
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to roadway safety devices and more particularly, to a guardrail beam with enhanced stability.
BACKGROUND OF THE INVENTION
A goal of roadway safety is to provide a forgiving roadway and adjacent roadside for errant motorists. Guardrails are employed along a roadside to accomplish multiple tasks. Upon vehicle impact, a guardrail must react as a brake and shock absorber to dissipate the kinetic energy of the vehicle. Subsequently, the guardrail acts as a mechanical guide to redirect the vehicle away from hazards during deceleration and to prevent the vehicle from leaving the road, becoming airborne or rebounding into traveled lanes of traffic.
For many years, a standard heavy gauge metal guardrail known as the “W-beam” has been used on the nation's roadways to accomplish these tasks and others. Named after its characteristic shape, the “W-beam” is typically anchored to the ground using posts made of metal, wood or a combination of both.
Recently, there has been a vigorous effort to raise the performance standards which guardrails must satisfy. Increasingly stringent testing criteria have uncovered serious deficiencies in the performance of standard “W-beam” guardrails. Accordingly, recent efforts have focused on development of a new guardrail system that will accomplish safety goals more effectively.
One such design included a deeper and wider “W-beam.” However, this change in geometry required a significant increase in hardware to attach adjacent sections of the beam at the splice. Alternative systems have not gained widespread industry acceptance.
SUMMARY OF THE INVENTION
One aspect of the present invention is to provide an improved guardrail system for use in median strips and adjacent to roadways that more evenly spreads the stresses sustained during impact with a vehicle to create a more uniform, stable and predictable response. Another aspect is to provide a cost-effective, retrofitable guardrail which can be employed interchangeably along with, or in lieu of existing guardrail systems. Yet another aspect is to provide a lightweight guardrail with the strength to meet or surpass highway safety standards. Still another aspect is to provide a guardrail capable of dissipating the impact energy of vehicle collision more effectively than existing guardrail systems.
Various technical benefits are attained in accordance with the teachings of the present invention by employing a guardrail beam with a top edge, bottom edge and a plurality of crowns disposed longitudinally between the top edge and the bottom edge. A first fold may be disposed longitudinally along the top edge and a second fold may be disposed longitudinally along the bottom edge. For one embodiment, the first fold and the second fold may have the general configuration of a tubular curl. For some applications, the first and second folds may be hemmed.
In a particular embodiment, one or more fluted beads may be disposed longitudinally along at least one crown.
In another embodiment, a plurality of bolt holes associated with the guardrail beam are configured to allow the guardrail beam to be used interchangeably with existing guardrail systems.
A technical advantage of the present invention includes its ability to effectively withstand and distribute stresses sustained during impact with a vehicle. This enhanced stress distribution minimizes failure of the guardrail beam and provides for a more stable and predictable response during collision. Accordingly, the guardrail beam can withstand significant forces of impact while maintaining adequate safety to vehicles, passengers, and bystanders.
Another technical advantage includes the use of thinner sheets of selected base materials to form sections of the guardrail beam which minimizes costs associated with fabrication, transportation and installation of the guardrail beam.
Still another technical advantage includes a bolt hole configuration which facilitates the retrofit and/or replacement of existing guardrail systems with one or more section of a beam formed in accordance with teachings of the present invention without requiring substantial modifications to existing equipment and other portions of each system.
Other technical advantages are readily apparent to one skilled in the art from the following figures, descriptions, and claims.
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Standard Specification for Corrugated Sheet Steel Beams for Highway Guardrail, AASHTO Designation: M 180-89, pp. 309-313.
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Hartmann Gary S.
Shackelford H.
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