Rail crossings are places where roads, footpaths, or other rights of way cross railway tracks. Crossings are a source of ongoing conflict between the needs of the railways and the needs of rail crossing users. Pedestrians, drivers, animals, and other users prefer that the crossings be as similar to or as consistent with the road surface as possible. Similarly, in road level railbeds such as those used for light rail, it is desirous to have the railbed and the road form as continuous a surface as possible. While the recessed areas on either side of the rails may be filled with road material and/or flangeway fillers, the interaction between the train, rail, and track ballast can still be noisy and the vibrations can lead to wear and tear on the rail. Additionally, electrical currents in the rail can interact with the ballast, increasing corrosion of the rail and decreasing a rail's lifespan.
Rail boots are designed to enclose and insulate a rail, leaving the running surface exposed. Insulating the rail with a flexible interface such as a rail boot decreases the wear on a rail, eliminates contact with stray currents, and reduces noise, vibration, and road traffic damage. Rail boots may also provide an interface between the rail and road material that can mitigate the impact of thermal expansion and contraction of both the rail and surrounding surfaces. However, rail boots also need to be able to respond to thermal expansion and contraction of both the rail and surrounding surfaces. Previous boot systems have experienced degradation due to weather fluctuations (e.g., diurnal and seasonal temperature variations, variations in precipitation (e.g., snow, sleet, rain, hail, etc.), and the like). The susceptibility of previous boots to inclement weather may stem from difficulties in simulating, testing, and modeling the performance of the boot material in the wide variety of weather conditions the boot may experience when in-use.
Additionally, rail boots absorb some of the force on the rail, limiting the amount of rail movement and the transfer of force to surrounding concrete and road surfaces, decreasing the need for road maintenance. Current rail boots are generally part of the stepped or interlocking components required to provide support where rail sections meet and are designed to be permanently embedded in asphalt or concrete, requiring complete removal of the flangeway system and adjoining roadway materials to access the rail hardware and components. A lack of durability in real world conditions has caused previous rail boots to exhibit material deformation, causing misalignment between the rail boot and rail and in some instances impeding roadway and rail travel. Furthermore, in practice, various regions of current boots and flangeway fillers may become contaminated with debris (e.g., gravel, sand, dirt, etc.). The debris contamination exacerbates the boot and filler degradation issues. Certain boot designs have also exhibited water draining issues which may decrease the traction of vehicles traveling across the boot.
There is therefore a need for alternative rail boots that allow for replacement of the rail boot and general maintenance on the rails and rail hardware in road crossings. There is also a need for alternate boot designs exhibiting increased durability and rail retention characteristics during normal and stressed operating conditions. The above issues have been recognized by the inventor herein and are not admitted to be known.
The following summary is intended to highlight and introduce some aspects of the disclosed embodiments, but not to limit the scope of the claims. Thereafter, a detailed description of illustrated embodiments is presented, which will permit one of skill in the relevant art to make and use various embodiments.
To overcome at least a portion of the aforementioned challenges, a rail boot designed to wrap around the sides and base of a rail, leaving the running surface exposed, is provided. The rail boot may comprise at least two flexible antennae which fit below the rail head of a rail and are in contact with the top fillet radius of a rail. The flexibility of the antennae allows the boot to achieve a desired degree of retention on the rail when installed. The antennae also allows the boot to achieve a stronger interface with a flangeway filler. Each antenna may be connected to a first end of a first or second cellular truss, respectively.
In some examples, the trusses may be arranged in face sharing contact with the web of the rail. The cells of the truss may be the same or different shapes containing the same or different volumes of air. Further, in some examples, the truss may be curved, such that the surface of the truss in contact with the web of the rail follows the shape of the rail, but the exterior or opposite side of the truss curves away from the rail such that the truss as a whole forms a substantially semi-circular or semi-oval shape. A second end of each truss may be connected on a respective side to the base of the rail boot which wraps around the base of the rail. Designing the trusses with this profile allows the structural integrity of the boot to be increased while also allowing for a targeted amount of boot deformation during installation. Consequently, the boot may be more securely attached to the rail and boot installation efficiency may be increased. Shaping the trusses in the aforementioned manner also increases the boot's ability to maintain a flangeway filler in a desired position in relation to the boot and rail.
In some examples, an inner surface of the base of the rail boot in contact with the base of the rail may be patterned, for example in a curved, rectilinear, triangular, wave, or other pattern. Such patterns may be regular or irregular. In some examples, the patterns on the rail boot extend along the length of the rail, allowing material to pass between the rail boot and the rail. The boot's water draining capabilities are therefore enhanced. However, in other examples, the inner surface of the base of the rail boot may be smooth.
Further in other embodiments, the rail boot may be extruded, co-extruded, cast, or molded in one or more pieces of one or more types of material. For example, the rail boot as described herein may include one or more elastomeric materials. Such materials may be elastomeric or plastomeric including, but not limited to: thermoplastic elastomer, ethylene propylene diene monomer rubber (EPDM), isoprene rubber, nitrile rubber (NBR), styrene-butadiene rubber (SBR), polyisoprene rubber, chloroprene rubber, and silicone, as well as additional natural or synthetic rubber polymers or thermoplastics. In some examples, such rubber polymers have a shore A hardness of 0 to 100, about 20 to about 90, about 60 to about 80 or any fraction thereof. In this way, the boot may achieve the desired amount of compliance, abrasion resistance, and shear strength characteristics. However, polymers exhibiting other hardness ranges have been envisioned.
In some examples, the thickness is graduated, being thinnest at the tops of the antennae and thickest at the base. Tapering the antennae in this manner increases the boot's ability to be retained against a rail, when installed. The antenna also enables a more robust attachment between the boot and a flangeway filler to be achieved, if desired. Rail boot longevity and durability is increased as a consequence of these retention features, resulting in increased customer appeal. In a further example, the rail boot may be thicker at the tip of an antenna than the body of the antenna. In other examples, the outside edge of the truss may be thicker than an antenna, but the walls between the cells of the truss may be the same or thinner than the antenna. While any useful thickness or graduation may be used, in some examples, the thickness of the rail boot may vary between 1/10″ to 5/16″. Designing the boot antenna within this thickness range can enable the rail to strike a balance between antenna flexion and structural integrity. Balancing these characteristics in this manner allows boot installation to be simplified, increases the strength of the connection between the rail and boot, and increases boot durability, in some scenarios. However, other rail boot dimensionality has been contemplated. In some aspects, the rail boot base may have varying thicknesses. For example, in aspects in which the inner side of the base of the rail boot is patterned or shaped, the portion of the base of the rail boot covering the bottom the rail may be thinner at some points than others. In other aspects, the portion of the rail boot covering the top of the base of the rail may be thicker than the portion of the rail boot covering the bottom of the rail base. In some aspects, the rail boot may fit snuggly around the rail. In other aspects, parts of the rail boot may be in face sharing contact with the rail while other parts are separated from the rail. For example, there may be a clearance allowance between the installed rail boot and the bottom filet radius of the rail. Such a clearance allowance may be of any amount that allows the rail boot to fit the rail. In some examples, the clearance allowance may be between about 1/64 to about ¼ of an inch or any fraction thereof. For example, in some aspects, the clearance may be 21/256 of an inch.
The rail boot may be shaped to assist in the positioning of additional components of a railway system. For example, in some aspects, the truss may be shaped to be in contact with a support leg of a flangeway filler. The flangeway filler may therefore be less susceptible to misalignment with the rail due to the contact with the truss. The flangeway filler may also assist in holding the rail boot in place. In other aspects, the rail boot may assist in fitting the flangeway filler into the space between the rail and the field or gage panel of the railway system.
In some aspects, the rail boot may be positioned such that the antenna and the truss assist in holding the rail boot in place through the use of potential energy, further increasing the degree of boot-rail retention. In other aspects, the rail boot may be held in place through the use of clips, bolts, zip ties, cable ties, adhesives, tapes, and the like. In further aspects, the rail boot may be held in place through a combination of potential energy and one or more binders or binding mechanisms.
Other objects, features and advantages of the present invention will be apparent from the following specification and drawings.
To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced.
Provided herein is a rail boot that encases a rail, leaving the head and running surface exposed. The rail boot is designed with increased durability as well as rail and flangeway filler retention characteristics, allowing the boot and the flangeway filler to maintain a desired position with regard to the rail after an extended duration of use under real-world conditions, in comparison to previous boot designs. This boot design correspondingly decreases the likelihood of the boot and flangeway filler impeding vehicular/train travel or becoming further degraded due to unwanted vehicular/train interaction with the boot or filler. These characteristics correspondingly increase the boot's lifespan and customer appeal. The rail boot surrounds the neck, web, and base of the rail and locks in place under the railhead. Specifically, the rail boot conforms to the rail profile, increasing (e.g., maximizing) its surface area contact with the rail. The boot's degree of retention on the rail, when installed, is therefore increased, decreasing the chance of undesirable boot deformation and boot-rail misalignment. In some embodiments, the rail boot is of a size and shape to provide sufficient clearance for other flangeway components such as a flangeway filler to lock in place underneath the railhead. This feature drives down the chance of filler misalignment with the rail which may, in some cases, cause filler degradation due to vehicular interaction with the filler. In various embodiments, the flangeway components may have no contact with the rail boot, or may be in contact with any desired part of the rail or rail boot including, but not limited to, the rail boot, the top of the railhead, underneath the railhead, the side of the railhead, the rail web, the rail base, or a combination thereof. The rail boot may be removable or permanently attached to the rail. In some examples, the rail boot may be replaceable without the need for destruction of the surrounding roadway. Consequently, the rail boot's adaptability is expanded, further increasing the boot's customer appeal.
The rail boot may be constructed of any suitable elastomeric or plastomeric material or combinations therefor. In some embodiments, it is constructed of a material that may store and release mechanical energy by reactive or deflective means. Increasing boot compliance in this manner increases the boot's ability to remain in a desired position once installed and can also increase the boot's installation efficiency, in some scenarios. Such materials include, but are not limited to, one or a blend of flexible elastomers. Suitable elastomeric substrates may include any of the thermoplastic or thermosetting polymer materials known in the art. Non-limiting examples of suitable flexible elastomeric materials include, but are not limited to thermoplastic elastomer, ethylene propylene diene monomer rubber (EPDM), isoprene rubber, nitrile rubber (NBR), styrene-butadiene rubber (SBR), polyisoprene rubber, chloroprene rubber, and silicone, as well as additional natural or synthetic rubber polymers or thermoplastics. In some examples, such rubber polymers have a shore A hardness of 0 to 100, about 20 to about 90, about 60 to about 80 or any fraction thereof. It will be understood, that shore A is durometer scale known in the art which uses a defined spring force and indentor configuration for generation of a hardness measurement.
The natural or synthetic rubber polymers may be produced by any means generally used. In some examples, the rail boot may be extruded, or if manufactured using a plurality of natural or synthetic rubbers and/or thermoplastics, such materials may be co-extruded. In other examples, it may be cast or molded. The resulting rail boot may be cured or cooled into its finished state by any means generally used. For example, it may be thermoset or flash cured in one or more layers. For example, thermosetting polymers may be vulcanized at temperatures above about 250° F. Forming the polymers in this manner enables the polymer's durability as well as rigidity to be increased, in some cases. In other aspects, thermosetting polymers may be vulcanized at temperatures below about 450° F. In one specific example, thermoplastics may set at temperatures below about 212° F.
The rail boot generally comprises a base and two sides which lock the rail boot in place under the railhead. In some examples, the rail boot may have antennae that flex during installation and conform to the shape of the rail profile. In some embodiments, the antennae are lodged under the railhead such that sufficient pressure is exerted by the elastomeric material to hold the antennae and hence the rail boot in place. In further embodiments, the pressure exerted by the elastomeric material is sufficient to hold the rail boot in place such that no additional adhesives or hardware are used. In one embodiment, the antennae have lower physical resistance than other parts of the rail boot, allowing for ease of deformation of the antennae to assist in installation of the rail boot. For example, the rail boot may be at its thinnest at the antennae, gradually thickening as it continues down along the rail web. Tapering the antennae in this manner allows the boot's flexion and stiffness to be granularly tuned to facilitate efficient rail installation and, once installed, to be firmly retained against the rail. In one aspect, the rail boot may thin again as it comes in contact with the base angle and/or base edge. In some embodiments, adhesives or caulking such as butyl tape, epoxy, or any useful synthetic or natural rubber base caulking or adhesive and the like may be used to hold the rail boot in place. The adhesives or caulking may be used to permanently bind the rail boot to the rail, or may be merely of sufficient strength to assist in the installation process. In further embodiments hardware such as, but not limited to, clips, tape, zip ties, binders, cords, cables, fasteners, bands, snaps, straps may be used to temporarily or permanently hold the rail boot in place. In additional embodiments, a combination of adhesives and hardware may be used. Such adhesives and hardware may be used on the field side of the rail, the gage side or both.
The thickness of the rail boot may be constant or variable. In some embodiments, the thickness is graduated. The thickness may affect the amount of pressure or force that may be captured and released by one or more portions of the rail boot. For example, in one embodiment the rail boot may be thinner at the base edge of the rail, improving the clearance of the encased rail for insulators. In further embodiments, the rail boot antenna and/or rail boot truss may be thinner than other parts of the rail boot, allowing for ease of installation. The rail boot antenna and rail boot truss may be of the same or different thicknesses. In additional embodiments, the base of the rail boot may be the thickest portion of the boot. The variability of thickness may range up to about 800% from one portion of the boot to another. In some embodiments, the thickness variation between the thinnest and thickest part of the boot may be about 500%. For example, in one embodiment, the thickness may be between about 1/10 inch (″) to ½″, 1/10″ to 5/16″, 1/16″ to 5/16″, or fractions thereof. However, other rail boot dimensionalities have been envisioned.
The rail boot may be constructed so that the antennae may yield to installation stress allowing for ease of installation. Once installed, the antennae exert pressure against the bottom head angle, holding the rail boot in place under the railhead. As the rail boot descends along the web of the rail, it may form a multi-cellular truss comprising one, two, three, four, five, six, seven, eight, nine, ten or more cells on one or both sides of the rail. The cells may independently be the same or different shapes and may contain the same or different volumes of space. In some embodiments, the walls of the cells are the same thickness all around. In other embodiments, the portion of the cells that sits against the rail web may be thinner than other parts of the cells. In additional embodiments, the elastomeric material of the walls between the cells may be thinner than elastomeric material of the walls of other parts of the cells. In some embodiments, one or more trusses may curve away from the rail. Such a curvature may allow the rail boot to slide past, along, or compress to allow for other components of the rail system to be installed in conjunction with the rail boot. In some examples, the structure of the truss or trusses allows it to be compressed in order for other components of the rail system to be installed. In one aspect, such compression allows for installation of other components of the rail system without disturbing the surrounding roadway. In other aspects, the rail boot may be installed as the rail system is built.
In one example, a truss allows for compression and deflection of stored energy to provide a vertical resistive force to maintain tension between the railhead and the rail boot antenna. The tension may enable a relatively high level of (e.g., maximum) contact between the rail boot and the profile of the rail. The tension created under the railhead and at the base radius of the rail creates pressure at both top and bottom ends of the truss, flexing it slightly at the truss centerline and forcing the rail boot into contact with the surface web of the rail with an inward horizontal force.
In a further embodiment, the flexibility and energy storage properties of the truss may be replaced by using a material with high levels of density such as a co-extruded or dual durometer thermoplastic elastomer, synthetic rubber polymer, or other semi or ridged substrate.
In some embodiments, the rail boot fits snugly along the web and around the bottom of the rail. In other embodiments, there may be a slight gap or clearance allowance at the bottom fillet radius between the rail and the rail boot. For example, such a gap may be between about 1/64 of an inch (″) to about ¼″ or any fraction thereof. In some examples, it may be 21/256″ at the base web radius between the rail boot and the rail. In some embodiments, this space allows for additional compression when horizontal installation force is applied, creating vertical resistive force to provide sufficient tension between the rail head and the rail boot antennae, allowing for increased (e.g., maximum) contact of the rail boot with the profile of the rail.
While the rail boot may be of variable or constant thickness, in some embodiments the rail boot may be thinner at the base edge, allowing for increased clearance for rail insulators or other rail installation components.
The interior of the bottom of rail boot against the rail may be uniform or corrugated. Such corrugations may be of any shape desired. In some embodiments, they may be angular, rounded, ridged, fluted, grooved, channeled, ribbed, or any of the like, alone or together, sufficient to generate an irregular surface. In some embodiments, the corrugation may be in a pattern. While the corrugation may serve any purpose desired, in some embodiments such corrugation may allow for the removal of liquid or debris that may build up along the rail, increasing the longevity of the rail. In additional aspects, the corrugation may allow for compression and deflection of energy as the train passes over the rail.
Those skilled in the art will recognize that it is common within the art to describe devices and/or processes in the fashion set forth herein, and thereafter use standard engineering practices to integrate such described devices and/or processes into larger systems. That is, at least a portion of the devices and/or processes described herein can be integrated into a railway system via a reasonable amount of experimentation.
The rail boot 100 may be constructed of any suitable material. In some embodiments, it is constructed of an elastomeric material with sufficient elasticity such that the rail boot 100 may be compressed to install the rail boot 100 around the rail and the release of stored energy from the compression may be used to hold the rail boot 100 in place around a rail. In this way, the rail boot is made more compliant to reduce the likelihood of the boot separating or otherwise exhibiting misalignment with the rail. Such an elastomeric material may be electrically conductive or non-conductive. As shown in
While the rail boot may be used on any type of rail, a cross-section of an illustrative rail on which a rail boot may be installed is shown in
Turning to
A gap 304 between the base edge radius and rail boot is shown. The gap 304 may be of any distance that allows for enough flex for the antenna to compress and seal the rail boot against the web. In some embodiments, the gap 304 may be between about 1/64″ to about ¼″ or any fraction thereof. However, other gap dimensions have been contemplated. Further, in some embodiments, the corrugations 122 increase the release of sand or debris in the event of a flood or buildup of condensation at the base of the rail, increasing the lifespan of the rail.
As shown in
As shown in more detail in
In the perspective view of
Turning to
In some embodiments, support leg 706 may be in contact with the second surface 306 of the truss. In other aspects, the support legs such as extended support leg 708 may be longer than the standard profile to assist in locking the rail boot 100 in place. In some examples, the field side flangeway filler may have a compression point 714, which aids in installation of the flangeway filler between the boot and the roadway. Installation time may be decreased when the filler includes the compression point feature. In additional aspects, a bolt such as U-bolt 710 may be used to reduce gaping in the field side flangeway filler 704 and gage side flangeway filler 702. In one example, the U-bolt 710 may be constructed out of stainless steel, reducing the likelihood of rust build-up on the bolt. The flangeway filler, in such an example, is made more robust and can be more easily disassembled for component repair or rearrangement, for instance. However, the U-bolt may be constructed out of other materials, such as carbon steel, in other examples. Both material properties and cost considerations may be taken into account when selecting the material construction of the U-bolt as well as the other flangeway filler and rail boot components, in some cases.
Further, in one example, rebar 750 may be included in the flangeway filler 704. The rebar 750 may extend longitudinally along the filler and may be designed to connect with a corresponding bore in an adjacent filler section. In some instances, the rebar may be coated with epoxy to provide corrosion resistance. However, the epoxy coating may be foregone, in other instances, due to cost, for example.
The rail boot 100 may have constant or variable thickness. In some embodiments, the rail boot 100 may be thinner from the bottom fillet radius 214 through the base angle 218 and over the base edge allowing for increased contact and installation efficiency of rail insulators rail insulators 712.
While the compressive force in the cells in the truss keep the boot upright and in place, in some embodiments, an adhesive can be placed along the inside 716 of the rail boot. The adhesive may be placed along the entire inside of the rail boot 100 or may be placed in strategic places such as along the portion of the rail boot 100 in contact with the web 212 of the rail 200. In this way, the boot may be more securely coupled to the rail, thereby decreasing the likelihood of unwanted boot movement relative to the rail.
References to “one embodiment” or “an embodiment” do not necessarily refer to the same embodiment, although they may. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” Words using the singular or plural number also include the plural or singular number respectively. Additionally, the words “herein,” “above,” “below” and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. When the claims use the word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list and any combination of the items in the list.
The foregoing described aspects depict different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being “operably connected”, or “operably coupled”, to each other to achieve the desired functionality.
While a preferred embodiment of the present invention has been illustrated, those skilled in the art will recognize that many modifications and variations are possible in accordance with the above teachings without varying from the spirit and scope of the invention. It is to be understood that such modifications and variations are within the spirit and scope of the present invention as set forth in the following claims.
The present application claims priority to U.S. Provisional Patent Application No. 62/813,531 entitled “RAIL BOOT,” and filed on Mar. 4, 2019. The entire contents of the above-mentioned application is hereby incorporated by reference in its entirety for all purposes.
Number | Date | Country | |
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62813531 | Mar 2019 | US |