Fences – Highway guard
Reexamination Certificate
1996-01-05
2001-07-17
Melius, Terry Lee (Department: 3628)
Fences
Highway guard
C256S059000
Reexamination Certificate
active
06260827
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to roadway guardrail systems, and more particularly, to guardrail barriers.
Guardrail barriers are positioned along roadways to prevent or reduce the damage to vehicles and to their occupants when they leave the roadway. The guardrail barriers are designed to redirect the vehicle back onto the roadway and to absorb energy in a controlled manner from the vehicle. The barrier is supported on posts or the like and may have different amounts of flexibility depending on its design. It provides an effective depth or capture area intended to receive the moving vehicle in a recessed portion of the guardrail barrier bounded by upper and lower curved portions projecting toward the roadway to stabilize the vehicle and reduce the tendency for the vehicle to vault over or dive under the barrier or to roll when redirected by holding the vehicle against upward and downward motion. The barriers should be positioned with the lower peak of the curved portions no higher than 20.5 inches from the ground. Terminals are located at the ends of the guardrail system's barrier to receive vehicles that hit at the end. The terminals and the barriers work together to absorb energy when the terminal is hit.
While prior art barriers differ one from the other and have many types of designs, the most common type of prior art barrier in the United States is a W-Beam, galvanized versions of which are dimmensioned to have an area of its cross sectional edge of 1.99 square inches (in.
2
), a thickness of its edge of 0.1046 inches (in.), a gauge of 12, a depth from the top edge vertically down to the bottom edge of 12.25 inches, an effective depth from the centerline of the uppermost curved portion of the barrier (horizontal radius) to the centerline of the lowermost curved portion (horizontal radius) of 7.63 inches, a width (from vertical plane touching the barrier at the point farthest from the road center to vertical plane touching barrier nearest road center—i.e. peak of positive curve to peak of negative curve) of 3.35 inches.
This standard W-beam has an Xbar (distance from lower edge vertically to centroid) of 6.13 inches, a Ybar (distance from peak of positive curve to centroid) of 1.69 inches, an Ix (vertical moment of inertia) of 29.65 in.
4
, a horizontal moment of inertia, Iy, of 2.32 in.
4
, an Sx (vertical section modulus) of 4.84 in.
3
, an Sy
1
(horizontal section modulus at positive peak) of 1.38 in.
3
, an Sy
2
(horizontal section modulus at negative peak) of 1.40 in.
3
, a length (length of edge of a section if it were straight) of 19 inches, and a weight per length of the barrier of 6.77 pounds per foot. The outer curved portions of standard w-beams are each symmetrical about a horizontal line through its peak. Usually, sections of w-beams are spliced together by eight bolts, one row of four bolts on each side of the post bolts, evenly spaced so that two of the four are on the outer section of the peak of each outer curve and two on the inner section.
Barriers with these dimmensions operate well on some vehicles but have several disadvantages as to other vehicles, such as for example: (1) they provide so much resistances to high center of mass vehicles that, under an undesirably large number of circumstances, they cause the center of mass to rise to a height over the vertical, resulting in the vehicle rolling or vaulting over the guardrail; and (2) certain vehicles with a high center of mass and high bumper mounting heights are not captured by the prior art W-beam guardrails. Thus, certain light trucks, such as pick-ups, vans and sport-utility vehicles may be caused to roll and sometimes vault over the guardrail barrier. However, the W-beam barrier cannot be raised because small cars would wedge under the railing and snag on the guardrail posts.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide a novel guardrail system.
It is a further object of the invention to provide a novel guardrail barrier or rail.
It is a still further object of the invention to provide a guardrail system in which the guardrail barrier captures higher center gravity vehicles such as pick-up trucks, vans, utility vehicles and the like.
It is a still further object of the invention to provide a novel guardrail system in which the guardrail barrier absorbs energy in a controlled manner such as for example by buckling, bending cutting or other metal working when the terminal is impacted.
It is a further object of the invention to provide a novel guardrail system in which the membrane characteristics of a guardrail are balanced against the beam characteristics to reduce the tendancy of vehicles with a high center of mass from rolling, vaulting over the guardrail barrier or diving under the guardrail barrier upon hitting the guardrail barrier.
It is a still further object of the invention to provide a larger capture area in a guardrail barrier to receive a wider variety of low bumpers and higher bumpers on vehicles.
It is a still further object of the invention to provide a novel guardrail able to usefully affect deceleration rates of impacting objects at low force levels and still function with high force levels.
It is a still further object of the invention to provide a novel guardrail formed of sufficiently thin material.
It is a still further object of the invention to increase the likelihood of fast local buckling quickly.
In accordance with the above and further objects of the invention, the shape of the guardrail barrier is tailored to reduce the tendancy of the vehicle to roll, vault over the guardrail or dive under the guardrail and to accomodate impact with an end terminal. It has been discovered that, with some designs, the tendancy of vehicles with a high center of mass to roll or vault over the guardrail barrier upon hitting the guardrail barrier can be reduced by reducing the thickness of the guardrail barrier sheet material and increasing the depth and effective depth of the barrier without significantly increasing the weight per unit length, the tendency to penetrate the occupant compartment and section modulus. The design also accomodates vehicles that impact the terminal end of the guardrail system or tend to dive under the guardrail barrier.
The beneficial results are obtained from a barrier having dimmensions falling within certain ranges such as for example a range of edge areas, reflecting the amount of steel or other material per unit length of guardrail barrier, and the effective depths. These ranges mean that each of the values must fall within the range for that value. This range is between an edge area of substantially 1.6 square inches with an effective depth of substantially 15 inches to an edge area of substantially 2.4 square inches with an effective depth of substantially 9 inches. The preferred edge area and effective depth are substantially 1.99 square inches edge area with substantially 12.25 inches effective depth.
A range of effective depths and moments of inertia is from an effective depth of 15 inches with a moment of inertia of 3.5 in.
4
to an effective depth of 9 inches with a moment of inertia of 1.5 in.
4
. The preferred moment of inertia is 2.39 in.
4
.
A range of peak crush strength is between 3 kips (one kips is equal to thousand pounds) per foot to 6.5 kips per foot. The preferred peaks crush strength is 4.97 kips per foot. A suitable range of energy absorption caused by impact is between 7 kips in. per foot and 15 kips in. per foot. The preferred value is 10.7 kips in. per foot or rail. This is best obtained by asymmetrical end curves with ratios of angles of the sloping inner side of outer curves to angles of outer side of curves (facing angles) with the vertical of 1.2 to 6. The preferred angles are 43.5 degrees for inner side and 78.66 degrees for outer curve with a ratio of 1.8.
To prevent tearing out bolts at between sections, more than 10 bolts in several rows should be used to hold the sections together. Each bolt should have a bearing area less than 0.079 square inches. The total be
Faller Ronald Keith
Pfeifer Brian George
Reid John Douglass
Rohde John Robert
Rosson Barry Thomas
Carney Vincent L.
Melius Terry Lee
Miller William L.
The Board of Regents of the University of Nebraska
LandOfFree
Guardrail system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Guardrail system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Guardrail system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2460840