Patent Application
20230374745
This disclosure relates to a preassembled traffic barrier system designed for the special application of road to anchor transitions, such as a bridge transition, where the transition resist deflection in multiple planes.
Road-side guardrails installed along highways protect motorists from the road-side hazards including non-recoverable slopes and rigid objects. The most common type of road-side protection is the American Association of State Highway and Transportation Officials (AASHTO) M 180 W-Beam Guardrail Panel (guardrail). Guardrail and other types of road-side safety devices are deemed ‘crashworthy’ or proven acceptable for use under specified conditions either through physical crash testing via AASHTO Manual of Assessing Safety Hardware (MASH) or in-service performance.
Where road-side guardrail is to be connected to a rigid object, such as a bridge barrier or bridge pier, the approach road-side guardrail is gradually stiffened so vehicular pocketing, snagging, or penetration at the point of connection between transition and a rigid object can be avoided. Pocketing is an undesirable behavior of guardrail involving relatively large lateral displacements within a relatively short longitudinal distance that can result in large longitudinal decelerations as the front of a vehicle contacts a portion of a barrier deformed at a sharp angle relative to the vehicle's path.
Penetration is the overall failure and separation of a guardrail, allowing an impacting vehicle to access an area of concern/hazard the guardrail intends to shield. Snagging is contact between a portion of a vehicle, such as a wheel or frame element, and the guardrail component that is approximately perpendicular to the normal direction of vehicle travel. The most common type of snagging is when a wheel engages the side of a guardrail post. The degree of snagging depends on the degree of engagement.
Transitions for locations where drainage features (e.g., curbs, drainage drop-basins, curb inlets, drainage swales, and public utilities (telecommunications, natural gas)) are constructed directly adjacent to the rigid object are susceptible to initiating vehicular instability that can, in some instances, adversely affect the crashworthiness of the transition. However, some transition designs incorporate a curb to reduce the probability of a vehicle snagging on the end of a ridged bridge railing. The most common method in practice today uses nesting or stacked w-beam or thrie-beam guardrail panels to stiffen the transition to a ridged object that has a relative short distance between the last transition post and the ridged object and, in many cases, is equivalent to a single guardrail transition post spacing (i.e., 2 ft. thru 3 ft 6 in.). This distance is problematic for utilities requiring a larger gap distance between the last transition post and the ridged object being shielded.
In addition to its application for use as a bridge transition, the disclosed barrier transition framework can be used in other locations where transitioning from a flexible barrier system to a solid barrier system. These would include, for example, transitioning from a W-Beam roadside barrier system to a rigid concrete or steel structure. The benefits of this application include providing a structure of intermediate flexibility capable of transitioning over drainage and utility features as described above.
Attempts to lengthen the transition span have resulted in systems that lack the tolerable transitional deflection limits needed for a bridge approach. One experimental attempt to increase the resistance to deflection when the span was increased included placing wooden poles between field-side facing and road-side facing W beams. While it provided additional resistance to deflection in the horizontal direction, it did not provide or allow the benefits of the spatial end anchoring of the present invention, required a field-side thrie-beam, required on site assembly which was cumbersome, and failed to provide the level of resistance to deflection achieved by the present invention.
A significant disadvantage of conventional guardrail bridge transitions is that they often conflict with utilities and drain structures. A disadvantage of conventional guardrail bridge transitions is that there is an eight-foot gap between the anchoring and post supported guardrail. The guardrail spanning is required to accommodate underground utilities and/or drop basin inlets for off structure drainage, rendering the guardrail spanning this space unreliable. Another disadvantage of conventional guardrail bridge transitions is that they are often anchored in poor soil conditions.
Another disadvantage of conventional guardrail bridge transitions is that they require an overpour of filler on hillsides leading to bridges. These provide unreliable foundations for anchoring guardrail posts. Another disadvantage of conventional guardrail bridge transitions is that drainage at the transition degrades the overpour of filler and poor soil surrounding support posts. Another disadvantage of conventional guardrail bridge transitions as they provide a guardrail that is too rigid, or too soft. An example of a guardrail that is too soft is one in which posts are secured in soft soil.
Therefore, there is a need for a guardrail bridge transition system that overcomes these disadvantages and provides a safer entry and exit between roads and bridges. Specifically, there is a need for a guardrail bridge transition assembly that accommodates utilities and drainage structures without interference, is not subject to poor soil foundation for securing guardrail posts and is not subject to excessive erosion by drainage. There is also a need for a guardrail bridge transition system that provides a greater resistance to deflection, even though extending over a longer span before attachment to a subterranean post. Finally, there is a need for a guardrail bridge transition that minimizes on location assembly and construction requirements.
An advantage of the embodiments of the disclosed guardrail bridge transition system is that it provides an improved performance that is applicable to both existing transition installations and new transition installations. Another advantage of the embodiments of the disclosed invention is that it comprises a sled component that arrives on-site preassembled and ready for installation. Another advantage of the embodiments of the disclosed invention is that it provides significant time savings on schedule, where post driving operations are reduced by eliminating at least three larger transition posts.
Another advantage of the present invention is that it can be used to replace in-service transitions, as well as new installations. Another advantage of the present invention is that it is fully reversable for use on either side of the road. Another advantage of the present invention is that it provides a visually seamless integration with a thrie-beam guardrail installed before the transition.
A primary advantage of the embodiments of the disclosed invention is that it provides a traffic bridge barrier system that uniquely resists deflection in multiple planes, thus providing safer entry and exit transitions between roads and bridges. Another advantage of the embodiments of the disclosed invention is that it provides a bridge transition assembly that accommodates utilities and drainage structures without interference by means of a longer span than conventional transitions. Another advantage of the embodiments of the disclosed invention is that it provides a system that is less vulnerable to failure due to poor soil features proximate to the bridge.
Another advantage of the embodiments of the disclosed invention is that it provides a foundation for securing guardrail posts that is less vulnerable to excessive erosion by drainage.
In summary, the disclosed invention provides a unique solution to the engineering constraints and challenges of providing a bridge transition that provides increased safety and cost-efficient installation and repair and overcomes the disadvantages of known solutions. Further, the embodiments of the disclosed invention satisfy the crash test requirements of AASHTO MASH Test Level 3, Test 3-20, and Test 3-21.
The advantages and features of the embodiments presently disclosed will become more readily understood from the following detailed description and appended claims when read in conjunction with the accompanying drawings in which like numerals represent like elements.
A transition framework and transition assembly are disclosed. In one embodiment, a prefabricated transition framework for use when transitioning from standard road barriers to an anchored road barrier, such as at the foundation of a bridge transition, is disclosed. The transition framework is a hot-dipped galvanized steel having a pair of 4½″ OD schedule 80 tubular chords. The ends of the tubulars are beveled and welded in solid connection to an approach deflector at one end and an anchorage plate at the other to maintain the tubulars in stiff parallel orientation.
As disclosed herein, the transition framework uniquely resists deflection in two planes, the horizontal plane and the vertical plane, thus providing a significantly improved performance over known previous designs. By anchoring the ends of the transition chords, vertical expansion of the impacted thrie-beam panel is resisted, absorbing more energy in the thrie-beam distortion and providing greater resistance to horizontal displacement. This allows the transition framework to provide the required stiffness while also providing a greater gap distance of 108 inches (9 ft.) between the center of a connecting transition post and a ridged bridge barrier. The tested and proven uninterrupted span of 105 inches accommodates all utilities at any transition requiring additional room (i.e., drop-basin for off-structure drainage, public utilities, etc.).
In one embodiment, a transition for anchorage to a concrete barrier at a bridge entrance is disclosed, comprising a tubular upper chord having first and second ends. A tubular lower chord is provided, also having first and second ends. The first end of each of the upper and lower chords is welded to an approach deflector. The second end of each of the upper and lower chords is welded to an anchorage plate. The transition as described provides a preassembled solid four bar assembly with exceptional strength and resistance to deflection in both the vertical and horizontal planes.
In another embodiment, the approach deflector is connectable to a subterranean mounted guardrail post, and the end anchor is connectable to a bridge anchor.
In another embodiment, the upper chord and lower chord have a 4.5″ outside diameter. In another embodiment, the upper chord and lower chord are schedule 80 tubulars. In another embodiment, the center of the upper chord to the center of the lower chord is separated by a distance of 15¼″.
In another embodiment, the first and second ends of the tubular upper chord and the first and second ends of the tubular lower chord are beveled.
In another embodiment, the approach deflector further comprises a weldment panel welded to the first beveled end of the upper and lower chords, a connection panel disposed at an obtuse angle to the weldment panel, and a plurality of vertically separated fastener holes on the connection panel for fastener connection to an embedded post. A deflection panel is disposed at an obtuse angle to the connection panel to prevent snagging of vehicles impacting the approach deflector.
In another embodiment, the anchorage plate further comprises a weldment panel welded to the second beveled end of each of the upper and lower chords, and a connection panel disposed at an obtuse angle to the weldment panel. A plurality of vertically separated holes is provided on the connection panel for receiving fasteners for connection to a concrete block at a bridge entrance.
In another embodiment, a bridge transition assembly is disclosed having a transition framework comprising a tubular upper chord having first and second ends, a tubular lower chord having first and second ends, an approach deflector welded to the first end of the upper and lower chords, and an anchorage plate welded to the second end of the upper and lower chords. The approach deflector is affixed to a guardrail post, and the anchorage plate is affixed to a bridge anchor. A first thrie-beam guardrail having a first end and an opposite second end is positioned on the road-side of the bridge transition, and over the upper and lower chords. The thrie-beam is affixed to the approach deflector and the guardrail post at its first end, and to a thrie-beam terminal connector at its second end. The terminal connector is attached to the anchorage plate and bridge anchor at its second end.
In a related embodiment, a second thrie-beam guardrail is provided, having a first end and an opposite second end. The second thrie-beam is positioned on top of the first thrie-beam in a nested configuration. The second thrie-beam is affixed to the first thrie-beam, the approach deflector, and the guardrail post at its first end, and to the first thrie-beam at its second end.
In another related embodiment, a field-side thrie-beam guardrail is provided.
The following description is presented to enable any person skilled in the art to make and use the invention and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and features disclosed herein.
A connection panel 38 is disposed at an obtuse angle to weldment panel 36. As best seen in
In one embodiment, upper chord 10 and lower chord 20 have an outside diameter of approximately 4.5″. In another embodiment, upper chord 10 and lower chord 20 are made from schedule 80 tubulars.
Also, in the embodiment illustrated, a second road-side thrie-beam 74 is nested over first road-side thrie-beam 70 to provide additional strength and resistance to deformation. As seen in this view, thrie-beams 70 and 74 have an accordion-like profile that is presented road-side for impact by a vehicle. The center of thrie-beams 70 and 74 would normally expand thrie-beams 70 and 74 vertically in response to a direct impact.
Unique to the present invention, the solid four bar configuration of transition framework 1 resists vertical expansion of thrie-beams 70 and 72, and coincident horizontal deformation. As disclosed, the impact of the disclosed invention requires horizontal buckling at the center of thrie-beams 70 and 72 between upper chord 10 and lower chord 20, which absorbs much more energy than horizontal expansion if upper chord 10 and lower chord 20 were not solidly anchored at their ends. The benefits increase resistance to deflection and increased probability of a repairable bridge transition on lower to medium vehicle impacts.
As further seen in
Field-side thrie-beam 80 is positioned on the field-side of transition framework 1, and over upper chord 10 and lower chord 20 so as to nest field-side thrie-beam 80 over upper chord 10 and lower chord 20. Fasteners 90 connect first road-side thrie-beam 70 to field-side thrie-beam 80 between upper chord 10 and lower chord 20 to form an envelope over upper chord 10 and lower chord 20.
First road-side thrie-beam 70 and second road-side thrie-beam 74 are connected to terminal connector 72 by threaded fasteners 62. The opposite ends of first road-side thrie-beam 70 and second road-side thrie-beam 74 are connected by threaded fasteners 90 to approach deflector 30 and guiderail post 110.
It is noted that the disclosed embodiments permit the addition of one or more second road-side thrie-beams 74 as nested over first road-side thrie-beam 70. It is further noted that the disclosed embodiments permit the inclusion of one or more field-side thrie-beams 80. Unique to the present invention, transition framework 1 does not require field-side thrie-beam 80 to support rigidly anchored upper chord 10 and lower chord 20, facilitating the very advantageous premanufacture of transition framework 1 for use at the bridge location.
Transition framework 1, as preassembled, can advantageously be used to replace in-service transitions, as well as new installations. Additionally, transition framework 1 is fully reversable for use on either side of the road. Transition framework 1 provides further significant installation time savings in that it eliminates up to four guardrail posts for post pounding operations.
In the embodiments illustrated, transition framework 1 and bridge transition assembly 5 permit a successfully MASH tested distance of 108 inches (9 ft.) between the center of guardrail post 110 and the edge of ridged concrete anchor 100. The tested and proven span of 108 inches provides 105 inches of uninterrupted space that accommodates all utilities at a structure requiring additional room (i.e., drop-basin for off-structure drainage, public utilities, etc.) to obtain the benefits of the invention. The increased span increases reliability as the primary guidepost is further distanced from the soil at the bridge interface.
In the TL3-20 testing, a 2,425-lb vehicle impacts the critical impact point (CIP) of the transition at a nominal impact speed and angle of 62 mi/h (100 km/hr) and 25 degrees, respectively. This test investigates a barrier's ability to successfully contain and redirect a small passenger vehicle.
On Apr. 19, 2022, testing was performed on the disclosed embodiment of the invention having a single field-side thrie beam 80 and a pair of nested road-side thrie beams 70 and 74. Table 1 below demonstrates the success of bridge transition assembly 5 in actual MASH testing on a small sedan weighing 2,603 lbs. performed by Applus IDIADA KARCO Engineering.
In the MASH 3-21 test, a 5000-lb pickup truck impacts the CIP of the transition at a nominal impact speed and angle of 62 mi/h and 25 degrees, respectively. This test investigates a barrier's ability to successfully contain and redirect light trucks and sport utility vehicles.
On Apr. 19, 2022, testing was performed on the disclosed embodiment of the invention having a single field-side thrie beam 80 and a pair of nested road-side thrie beams 70 and 74. Table 2 below demonstrates the success of bridge transition assembly 5 in actual testing on a 2006 Dodge Ram 1500 weighing 4,950 lbs. performed by Applus IDIADA KARCO Engineering.
As seen from the test results, transition framework 1 as incorporated in bridge transition assembly 5 provides a safe bridge transition for vehicles of very different sizes that passes all criteria of MASH Test 3-20 and MASH Test 3-21 requirements and provides the several advantages described herein.
It will be readily understood by a person of ordinary skill in the art that transition framework 1 and transition assembly 5 are not limited to the application of bridge entrance and egress, but can be used where other solidly anchored road barrier elements need to be transitioned to less resistive barrier elements.
Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and, in a manner, consistent with the scope of the invention.
This application claims priority to Provisional Application 63/343,828, filed May 19, 2022.
| Number | Date | Country | |
|---|---|---|---|
| 63343828 | May 2022 | US |
