US20030164403A1

US20030164403A1 - Elastomeric railroad crosstie

Info

Publication number: US20030164403A1
Application number: US10/351,763
Authority: US
Inventors: John Fitch; Richard Knittel
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-01-29
Filing date: 2003-01-27
Publication date: 2003-09-04

Abstract

A plurality of elongated, substantially planar, elastomeric members are assembled together in a stack such that the members are generally aligned with each other. The members are made of a stack of tire treads. A means of binding is provided for holding the stack of members together and maintaining their alignment. The addition of one or more rigid longitudinal element(s) provides stiffness.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to railroad crossties.

2. Description of the Related Art

Conventional treated wooden railroad crossties eventually rot and must be disposed of and replaced. It is estimated that the average life of a wooden railroad tie is only fifteen years. Concrete crossties, a more recent innovation, have a history of breaking. Rotted and broken crossties can lead to train derailments. What is needed is an inexpensive, long-lasting railroad crosstie which neither rots nor breaks.

Most railroad crossties used in this country today are lumber beams, approximately seven inches thick by nine inches wide by eight and a half feet long, which have been cut from sections of tree trunks selected to be free from decay, worm holes, and other imperfections. Before being placed into service as crossties, these beams are treated with chemicals to protect them against exposure to weather, insects, and microbes.

The treatment used on the wood crossties can be creosote, an oily liquid preservative, or chromated copper arsenic, or other chemicals. When rain, snow, and other weather elements impact on crossties which have been placed in a stone ballast roadbed, these chemicals migrate into the surrounding soil, producing a harmful environmental effect.

The sun has an evaporative effect on the chemical treatment of the wood crossties. As this evaporation of the chemical preservatives continues, the cellulose wood fibers become exposed, and this leads to the degradation of the wood crossties.

When taken out of service due to disintegration, the disposal of treated wood crossties causes another environmental problem. Many of the state Environmental Protection Agencies do not allow creosoted wood crossties to be burned or incinerated because of the emission of toxic fumes. The acid-treated wood ties can be granulated and buried, however this also pollutes the soil. Some ties are sold for landscaping or burned as fuel in specialized furnaces, but many must be buried underground, as some state and local laws prohibit their being burned in the open or being left along the railroad right-of-way for extended periods of time.

The normal service life of a wooden crosstie is about thirteen years. There are many crossties, however, that are in service well beyond this time period. These older ties are generally splitting and rotting, and cannot hold a cut spike (fastener). These older ties are leaching harmful chemicals into the soil, and potentially causing derailments.

Because wood crossties have a very limited useful lifespan, they must be replaced regularly. The U.S. railroad industry replaces approximately 15 million lumber crossties annually. New lumber crossties must be purchased and treated, transported to the rail lines, and distributed along the railbeds. They then must be installed using complex machinery and much skilled labor. During this process, the affected rail lines are shut down for days at a time. The cost to the industry, in terms of materials, labor, and disruption of rail service, is enormous.

Thus the major disadvantages of using lumber beams for railroad crossties are the ever-increasing cost of raw lumber, the difficulty of applying creosote or other preservatives with sufficient penetration to prevent rapid deterioration, the negative environmental impact of the chemicals used to treat wood crossties, and the expense of continually replacing crossties that are split or rotten.

Previous attempts have been made to develop a substitute for the conventional wood crosstie. One such attempt, as shown in Groff U.S. Pat. No. 3,289,940, involved manufacturing ties from synthetic resins. Other attempts include ties made from steel, concrete, or thin particleboard sheets made from recycled wood crossties or other lignocellulosic materials and laminated together (see U.S. patent references cited). These attempts have not been successful in replacing wood ties on a large scale, due to several factors, including higher cost, lack of sufficient strength and durability to withstand the cyclical bending loads peculiar to crossties, and non-adaptability of some materials to spikes or screws for fastening rails to crossties.

Accordingly, a need exists for a substitute for the conventional wooden crosstie that will successfully solve the problems of high original cost, frequent replacement, and polluting disposal.

BRIEF SUMMARY OF THE INVENTION

The present invention consists of a new form of railroad crosstie, made primarily of used vehicle tire treads, bound together and stiffened by the addition of a stiffening element. The present invention is easy to manufacture, very low in cost, and will greatly outlast wooden crossties, thus significantly increasing the economic efficiency of the railroad industry. The present invention is environmentally neutral, and uses up an abundant consumer and business byproduct, namely used tires, which currently present serious environmental problems due to the difficulty of disposing of them. The present invention replaces lumber crossties, which consume scarce lumber resources and which present environmental problems both during their useful lifespan and at disposal.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a side elevation of the railroad crosstie of the present invention. [0015]
FIG. 2 is a sectional end view of the railroad crosstie of the present invention. [0016]
FIG. 3 is a top view of the railroad crosstie of the present invention.[0017]

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a side elevation of the railroad crosstie of the present invention, which preferentially includes a plurality of elongated, substantially planar [0018] elastomeric members 10. The members 10 are assembled together in a stack such that the members 10 are generally aligned with each other. The members 10 may each be of the full length of the crosstie, or may be less than the full length, in which case the members 10 are butted end-to-end as shown. The ends 18 of such shorter lengths of elastomeric members 10 meet within the body of the crosstie.
The drawing shows the [0019] binding units 14 being comprised of straps of a flexible material. The binding units 14 keep the members aligned, and prevent them from shifting under the weight and movement of a train on the rails.
In the preferred embodiment, the [0020] binding units 14 also provide compression of the members 10. The passage of a train typically causes a temporary depression a section of crossties, as can be observed when a loaded train passes over a given section of track. Following this depression, there is a lifting moment as the rail assembly returns to its original configuration. This cycle of depression and lifting becomes greater as the speed and weight of the train increase. Beyond certain thresholds of train speed and weight, a sufficient compression of the members 10 by the binding apparatus 14 is required to prevent undue movement of the surface of the crosstie when exposed to these cyclical depressing and lifting moments.
This figure shows a [0021] stiffening element 17 comprising a piece of steel angle iron placed along an upper corner of the crosstie. The stiffening element 17 is enclosed within the binding units 14, which serve to keep the stiffening element 17 bound against the elastomeric members 10.
FIG. 2 shows an end-view cross-section of the crosstie of the present invention. The drawing shows two [0022] stiffening elements 17, comprising pieces of angle iron, held against the elastomeric members 10 by means of the binding units 14. Other embodiments of the present invention utilize one or more stiffening elements placed at different locations along the outside of, or embedded within, the body of elastomeric members. The stiffening elements may be either metal or other materials.
FIG. 3 shows a top view of the crosstie of the present invention. The [0023] stiffening elements 17 overlap the top of the uppermost elastomeric element 10, and are bound to the body of the crosstie by the binding units 14. This figure shows the binding elements 14 arranged in a staggered formation along the length of the crosstie. In the preferred embodiment, the binding units 14 cross approximately three-fourths of the width of the top of the crosstie and then penetrate the stack of elastomeric members 10.
The drawings illustrate one of many possible embodiments of the binding [0024] units 14. Other embodiments of the present invention utilize rigid binding units, as for example, welded metal units; and other embodiments may also require the use of binding methods other than welding, such as screws, bolts, crimping, adhesives, thermal processes, or other methods.
The forgoing descriptions relate to embodiments of the present invention which include the preferred embodiment, and are not meant to limit the scope of the invention. From the forgoing descriptions, many variations will be apparent those skilled in the art that would be encompassed by the spirit and scope of the present invention. Accordingly, the scope of the invention is to be limited only by the claims thereof and their legal equivalents. [0025]
The railroad crosstie of the present invention includes a plurality of elongated, substantially planar, elastomeric members. The members are assembled together in a stack such that the members are generally aligned with each other. In the preferred embodiment, the members are made of tire treads cut from vehicle tires, included but not limited to car, truck, and trailer tires. Elastomeric members formed specifically for this invention, and not made from tire treads, would also be within the scope of the present invention. Additionally, the stack of elastomeric members could be replaced by a single elastomeric member of a thickness, density, and strength sufficient for the intended use. [0026]
Some of the tire treads available for use in the present invention are of a length equal to or greater than that of a standard crosstie, whereas other treads may be shorter than the full length of a crosstie. As the drawings show, the shorter lengths of tread can be laid end-to-end within the stack of treads. [0027]
A means of binding is provided for holding the stack of members together. The binding means can include flexible or rigid fasteners, such as straps or metal rods, and may utilize means of joining such as bolts, screws, rivets, crimping, or welding. Additionally, the elastomeric members may be directly attached to each other through the use of adhesives or chemical or thermal processes. [0028]
One or more stiffening elements are incorporated within, or placed along the outside of, the stack of elastomeric members. The binding units can be attached to the stiffening element(s) to facilitate the assembly of the crosstie, or to increase the overall rigidity of the crosstie. In various embodiments of the present invention, the binding means and the stiffening element(s) may be separate, or may be attached to each other, or may be incorporated together. [0029]
One purpose of the stiffening element(s) is to resist the flexion or distortion of the crosstie that may occur during the process of installing the crosstie. In current practice, the replacement of worn and rotted wooden crossties utilizes machinery that inserts the new crosstie under the rails by picking up the crosstie at one end and sliding it under the rails. Thus the crosstie must be stiff enough to be handled in this fashion. [0030]
Another purpose of the stiffening element(s) is to prevent flexion of the crosstie when, due to erosion or movement of the stone ballast supporting the crosstie, the crosstie is supported in the middle but not well supported at one or both ends. In this situation the weight of passing trains tends to bend the crosstie down at the ends. This bending could, over time, cause misalignment of the rails. Therefore the stiffening element(s) help maintain the correct alignment of the rails. [0031]
Rail plates can be attached to the crosstie of the present invention by inserting spikes or screws through the plates and into the elastomeric members. [0032]
It is an additional objective of the present invention to provide such a railroad crosstie that, by virtue of the inherent flexibility of the primary material from which it is made, it is particularly resistant to cracking at specific locations along its upper and lower surfaces due to bending-induced cyclic tensile stresses peculiar to railroad ties. [0033]
It is an additional objective of the present invention to provide a crosstie that will have a long service life, far in excess of that of conventional wooden crossties. [0034]
It is an additional objective of the present invention to provide a crosstie that will be inert an friendly to the environment, creating an end-use product out of vehicle tires that are currently going into landfills, are shipped offshore, or are accumulating in dumps and creating environmental problems. [0035]
Because the present invention is assembled preferentially from tire treads, recyclable materials will be used instead of lumber, which is expensive and in short supply. [0036]

Claims

We claim:

1. A railroad crosstie comprising:

a. a plurality of elongated, substantially planar, elastomeric members assembled together in a stack such that the members are generally aligned with each other;

b. a means of binding the elastomeric members together and keeping them aligned with each other;

c. one or more stiffening elements placed longitudinally within, or along the outside of, the stack of elastomeric members, composed of a substantially rigid material, sufficiently rigid to prevent excessive flexion and deformation of the crosstie.