Wave Amplitude Attenuation and Wear Prevention Methods for Non-Wood-Timber Railroad Ties

Abstract

Non-wood-timber (NWT) railroad ties such as concrete remove cushion and pressure wave attenuation provided by wood timber railroad ties. I provide methods to reintroduce cushion and wave attenuation by means of adding an elastomeric sole. To further increase wave attenuation a layer of ground automobile tire is placed between the hardpan and ballast. Also, reclaimed asphalt is an inexpensive means to create hardpan that reduces railroad tie pumping.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable. The invention has no sponsor.

REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

Definitions for this patent application are:

• • the word sole refers to the material that isolates the railroad tie from ballast.
  • a non-wooden-timber railroad tie shall be denoted “NWT tie.”
  • aramid fibers such as poly-para-phenylene terephthalamide may be referred to by the trade name Kevlar a trademark of DuPont or Twaron a trademark of Teijin.

Railroads the world over traditionally utilize wooden timber ties 1 placed in a rock ballast 2,4 as seen in FIGS. 2 and 3. The ties 1 maintain the gauge or distance between the steel rails 3. Steel spikes and plates, not shown, affix rails 3 to wood ties 1. Ties 1 are placed atop a ballast base 2 that forms the leveled way for the ties 1 and rails 3. Between the ties 1 tamped ballast 4 presses or grips wooden timber ties 1 and prevents tie 1 sliding in the horizontal plane. All these pieces: ties 1, ballast base 2, and tamped ballast 4 are necessary to maintain parallel rail 3 congruency in 3-dimensions. Below the ballast base 2 a hardpan 5 frequently forms from the mixing of ballast 2 with the soil. Hardpan 5 maintains a solid hard surface while dry.

FIG. 4 is a load diagram for rectangular wood ties 1. Wood ties 1 are always rectangular, although only two surfaces need to be flat—those in contact with the rail 3 and ballast base 2. Saw mills typically have a stationary blade perpendicular to the cutting table, and as such all four sides of a wood tie 1 are typically cut at right angles. Rectangles are also easy to handle, stack, and use for systematic building practices like the railway. In the completed railway the wood tie 1 receives continues pressure from the tamped ballast 4. Wood is a fibrous resilient material capable of resisting tearing from the harsh grip of ballast 2,4 and resist the compression waves from train rolling stock. The rail 3 above transmits rolling stock pressure waves into the tie 1 and then tie 1 transmits the dynamic load into the ballast base 2. The wood tie 1 is the softest material between the rolling stock and the hardpan 5. The wood timber tie 1 provides a cushion and pressure wave attenuation between the steel rail 3 and the hardpan 5. Wood has the great characteristics of Modulus of rupture and Impact bending as defined by the United States Department of Agriculture Forest Service Wood Handbook: Wood as an Engineering Material technical report FPL-GTR-190. These two characteristic traits define the deflection and rebound in wood after the weight of each train wheel passes over the wood tie 1. The traits act as a shock absorber or cushion to reduce pressure wave amplitudes by flexing long wood fibers. Energy is further attenuated by the reduced wave velocity and extended travel time in the low density wood. As a result the low density further insulates the steel rail 3 from the ballast base 2 and hardpan 5. Energy reflected by the hardpan 5 and ballast base 2 are again attenuated in the wood tie 1 before transmitting upward into the rail 3 and finally into the rolling stock above.

An oak hardwood tie's 1 life span is between 30 and 50 years, a person's working lifetime. Old growth forests capable of supplying large wood timber for making wood railroad ties 1 are no longer plentiful. Wood tie 1 costs increase with feed stock scarcity. Attempts to increase wood tie 1 longevity such as U.S. Pat. No. 4,609,144 “Railroad tie cover,” have not proven effective. Rail systems around the world are substituting NWT ties 6 (FIG. 5) such as the trapezoid ties 7 (FIG. 6,7) often made of concrete and similar to U.S. Pat. Nos. 4,253,817 and 5,135,164 as well as rectangular tie 11 (FIG. 9) and other 6 NWT ties for the traditional wood tie 1.

NWT 6 ties have been successful for passenger rail and light tonnage rail cars, but have not proven as durable in heavy tonnage railways which comprise a large percentage of the North American rail industry. Also, the extensive quantity of wood ties 1 and ballast 2,4 employed in North America prohibits changing the railway system.

The purpose of all railroad ties is to maintain rail system congruency in 3-dimensions; however, tamped ballast cannot grip NWT ties 6,7,11 in order to maintain rail system congruency. As result the NWT ties 6,7,11 shift position, which creates a wavy track in 3-dimensions as seen in FIG. 5 and FIG. 6.

A popular substitute, trapezoid ties 7 made of concrete provide no cushion or wave energy attenuation; rather concrete provides a dense medium for fast transmission and reflection of pressure waves between the train, rail 3, ballast 2,4, and hardpan 5. Waves bouncing around in the rock hard railway system combine to create amplitudes large enough to fracture rails, wheels or other important rigid metal parts that easily transmit high frequency large amplitude waves.

Furthermore, concrete ties like the trapezoid tie 7 are prone to erosion on the bottom and sliding transversely and longitudinally since the ballast 2,4 cannot grip concrete. Trapezoidal shaped ties 7 (FIG. 8), narrower at the top, allows tamped ballast 4 to vibrate upward and reduce compactness further reducing grip. The ballast base 2 pulverizes the concrete since concrete lacks wood's ability to deflect and rebound on a small scale, FIGS. 6 and 7. Waves created by rolling stock vibrate the concrete ties permitting them to slide in the absence of a grip between ballast and concrete. Sliding places an undue burden on the rails 3 to prevent tie sliding and maintain congruency. The burden fatigues rails and increases failure rates. Uneven concrete erosion creates gaps between ties 7 and the ballast base 5, which cause ties 7 to vibrate and or pump vertically as indicated by the arrow in FIG. 6. Pumping also places further undue fatigue on rails 3 which further exacerbates failure rates.

FIG. 8 is a typical trapezoid tie 7 made of concrete. Metal spring clip holders 8 are cast into the cement. Pre-stressed wires 9 reinforce the concrete. Ballast triangles 10, interlock with ballast as much as they deflect it and loosen tamped ballast. Approximate weight is 800 lbs. verses 200 lbs. for a wood timber tie 1. Concrete tie 7 life expectancy of 10 years is much shorter than wood ties 1 life of 30 to 50 years, which creates more frequent maintenance intervals and cost.

U.S. Pat. No. 5,820,887 is a production method for producing concrete ties similar to FIG. 8. Such a production method is used by LBFoster to produces CXT® Concrete Ties, as seen in a picture in the portable document file (PDF) for 505S concrete ties available on the company's website.

FIG. 9 is a rectangular tie 11 frequently made of plastic, which has similar dimensions and density as wooden ties, but lack long molecular fibers joining the tie throughout. Plastic is softer than ballast. Ballast's course grip grinds away the soft loosely joined plastic. Plastic bolt holes 12 have a onetime use, after which the tie must be discarded. The plastic rectangular tie 11 life expectancy is much shorter than wood ties 1, which creates more frequent maintenance intervals and cost.

Other than ties, Hot Mixed Asphalt (HMA) and Rubber Mixed Asphalt (RMA) are employed a as base under NWT railroad ties 6. Both HMA and RMA are laid over the ballast base to prevent course ballast contact with NWT ties. Cost and logistics of hot bituminous substance are the primary problems with hot asphalt products.

Another concern with the railway is tie pumping where hardpan does not form due to poor subgrade that liquefies under loading or as a result of poor drainage. As tonnage laden wheels pass over a weekend area the tie's vertical motion creates waves that penetrate the subsurface and reflect upward and carry along with them debris that fills the gaps in the ballast. A vacuum condition between the tie, ballast and debris forms and the vertical motion of the tie creates a pumping action that increases mud and water suction from the subgrade. NWT tie pumping severity is worse than wood timber ties due to the aforementioned tie bottom erosion as the ballast acts as a grinder to pulverize the weakly bonded material of the NWT tie.

BRIEF SUMMARY OF THE INVENTION

Methods for increasing the lifespan of NWT railroad ties are described.

• • FIG. 11, reclaimed asphalt 14 is an inexpensive artificial hardpan. In combination with reclaimed asphalt, a geotextile 15 placed on the soil further stabilizes soft areas by distributing forces over larger areas.
  • FIG. 11, automobile tire shreds or tire chips 17 between the hardpan 5,14 and ballast base 2 attenuates pressure wave amplitudes. A fabric material 16 placed between the ballast 2 and tire pieces 17 prevents tires pieces 17 upward migration into the ballast 2.
  • FIG. 12, 13, 22, 23 an elastomeric sole material 13,19,20 is applied or integrated into NWT ties 6 to prevent erosion by ballast 2 materials, attenuate wave amplitudes and frequencies, as well as maintain three dimensional congruency.
  • FIG. 22 through 36 inverted trapezoidal profiles, with the small face down and large face up, create the “wedge” railroad tie 18,20. The wedge maintains the tamped ballast 4 locked in place and ballast 2,4 grips the tie's elastomeric wrap around sole material 19,20 to reduce wave amplitudes and frequencies, as well as maintain three dimensional congruency.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1: Isometric View of Railroad Tie Improvements

FIG. 2: Prior Art Top View of Wood Timber Railroad Ties in Ballast

FIG. 3: Section 1: Prior Art Wood Railroad Ties

FIG. 4: Prior Art Rectangular Wood Ties Load Diagram

FIG. 5: Prior Art Top View of NWT Railroad Ties in Ballast

FIG. 6: Section 2: Prior Art Trapezoid Railroad Ties Similar Shape To U.S. Pat. Nos. 5,135,164 & 4,253,81

FIG. 7: Prior Art Trapezoidal Tie Load Diagram

FIG. 8: Prior Art Trapezoid Concrete Tie Similar Shape To U.S. Pat. Nos. 5,135,164 & 4,253,817

FIG. 9: Prior Art Rectangular Tie

FIG. 10: Top View of Improved NWT Railroad Ties in Ballast

FIG. 11: Section 3: Railway Improvements

FIG. 12: Section 4: Bottom Soled Ties

FIG. 13: Bottom Soled Tie Load Diagram

FIG. 14: Soled Trapezoid Tie Similar Shape To U.S. Pat. No. 5,135,164

FIG. 15: Soled Rectangular Tie

FIG. 16: Flat Sole Multiple Lugs

FIG. 17: Flat Sole Multiple Lugs

FIG. 18: Flat Sole Simple

FIG. 19: Flat Sole with Wide Lug

FIG. 20: Wrap Around Sole Simple

FIG. 21: Wrap Around Sole with Lugs

FIG. 22: Section 4: Wedge Ties with Wrap Around Sole

FIG. 23: Wedge Tie Load Diagram

FIG. 24: Wedge Tie Profile

FIG. 25: Wedge Tie Profile

FIG. 26: Wedge Tie Profile

FIG. 27: Wedge Tie Profile

FIG. 28: Wedge Tie Profile

FIG. 29: Wedge Tie Profile

FIG. 30: Wedge Tie Isometric

FIG. 31: Wedge Tie Isometric

FIG. 32: Wedge Tie Isometric

FIG. 33: Wedge Shaped Tie

FIG. 34: Wedge Shaped Tie with Wrap Around Sole

FIG. 35: Square Shaped Tie with Wedge Wrap Around Sole

FIG. 36: Trapezoid Shaped Tie with Wedge Wrap Around Sole

FIG. 37: Conforming Wrap Around Sole

FIG. 38: Conforming Wrap Around Sole with Lugs

FIG. 39: Wedge Wrap Around Sole

FIG. 40: Wedge Wrap Around Sole with Lugs

FIG. 41: Wedge Wrap Around

FIG. 42: Wedge Wrap Around with Lugs

DETAILED DESCRIPTION OF THE INVENTION

• • FIGS. 11, 12 and 22 a geotextile 15 or similar products placed over the soil to distribute forces over larger areas increases railway stability and reduces tie 1,6 pumping.
  • FIGS. 11, 12, and 22 reclaimed asphalt 14 creates a hardpan where naturally occurring hardpan 5 fails to form under the railway. Asphalt removed from automobile roadways is inexpensive and compacts well to create a hard superficies. Examples of other similar uses are rural driveways and parking lots made of reclaimed asphalt 14 rather than gravel. In a similar manner reclaimed asphalt 14 creates a hardpan for the railway. Reclaimed asphalt may be utilized in both wood timber 1 and NWT railroad tie 6 applications. Reclaimed asphalt 14 applied atop geotextile 15 further increases the hardpan effectiveness, increases railway stability and reduces tie 1,6 pumping.
  • FIGS. 11, 12, and 22 applied atop the hardpan 5,14 a thin layer of shredded automobile tires pieces 17 attenuate pressure waves created by rolling stock on the railway. Tire pieces 17 span the tie 1,6 width. Spanning wider will have limited attenuation improvement and increases the possibility of tire pieces 17 contaminating the ballast 2. Moreover, shredded tire pieces should be applied intermittently in the railway (e.g. 100 yards applied followed by 100 yards not applied) in order to allow ballast 2 direct contact with the hardpan 5,14 to which will anchor the railway or alternatively the layer thickness should be sufficiently thin to all the majority of ballast 2 direct contact with the hardpan 5,14.
  • FIGS. 11, 12, and 22, atop the tire pieces 17 a fabric material prevents tire pieces 17 from contaminating the ballast base 2. Fabric will be suitable for resisting tears from ballast stress, yet provides sufficient pores to allow water drainage and prevent hydraulic pressure accumulation.
  • The improved Non Wood Timber (NWT) railroad tie 6 has many different shape possibilities that form a subset of the NWT tie 6. The characteristic all improved NWT ties share is incorporation of an elastomeric sole 13,19,20. Exemplary NWT subset shapes are:
    • trapezoid tie 7, wide face down, narrow face up and similar in shape to U.S. Pat. Nos. 5,135,164 and 4,253,817 is typically composed of concrete, yet other materials would also be suitable for the trapezoid shape as seen in FIGS. 12, 13 and 14;
    • rectangular tie 11 made of concrete, plastic, metal, or other material combinations as seen in FIG. 15 and installed in similar fashion as seen in FIGS. 12 and 13;
    • wedge tie 18 has the wide face placed upward and the narrow face down on the ballast base 2, for the wedge footprint is augmented by tamped ballast 4 as seen in FIGS. 22 and 23. Example wedge shapes 18 are seen in FIGS. 24 through 36.
  • FIGS. 12 through 23 and 34 through 42, the elastomeric sole 13,19,20 materials may be, but are not limited to, butyl rubbers, siliconized rubbers, acrylonitrile butadiene styrene plastics, other elastomeric materials, wood, polyvinyl chlorides, ferrous and non-ferrous materials and or any combinations of materials or other composites including aramid fiber dispersed in elastomer. The soles 13,19,20 may incorporate a woven foraminous or non-foraminous fabric belting material in the sole 13,19,20 similar to that of an automobile tire with nylon and or steel belts. The belting material maintains the sole's integrity by preventing ballast from piercing through the sole. Belting materials may be, but are not limited to, steel, nylon, Kevlar, other ferrous and non-ferrous materials or similar materials and or any combinations of similar materials. The sole 13,19,20 shall not incorporate air and water channels to move water away from the tie 1,6. Any such channel as in U.S. Pat. No. 4,609,144 will collapse under rolling tonnage and quickly form blockages from debris. However, grooves, a pattern or a texture on the outer surface of the sole may be appropriate for interacting with ballast 2,4. Should reinforcement bar or enforcement wire oxidation be a concern with the sole 13,19,20, then epoxy coating may be appropriate for ferrous enforcement materials.
  • FIG. 12 is a typical cross-section of trapezoid 7 and rectangular 11 ties. Soled ties 7,11 are installed in the same manner currently used to install NWT ties 6. FIG. 13 details the loading present on NWT ties 7,11. The sole 13 protects tie 7,11 bottoms from ballast erosion, attenuates dynamic wave energies, and prevents sliding. Tamped ballast 4 is unable to load either trapezoid ties 7 or rectangular ties 11.
  • FIGS. 14 and 15 are isometric views of trapezoid 7 and rectangular 11 ties with a sole 13 applied to the NWT ties 6.
  • FIGS. 16 through 19 are some possible configurations of elastomeric soles 13. The best method for attaching the sole to the NWT tie 6 will vary with specific application.
  • FIGS. 20 and 21 are wrap around soles 19 that provide grip to tamped ballast 4 while preventing ballast 4 erosion of the NWT tie 6.
  • FIGS. 22 and 23 present the inverted trapezoidal profiles, with the small face down and large face up, to create the “wedge” railroad tie 18. The wedge maintains the tamped ballast 4 locked in place and ballast 2,4 grip the tie's elastomeric wrap around sole material 19 without tie 18 erosion. Tie materials are not limited to concretes or plastics, and include metals and other composite materials.
  • FIG. 23 further explains the loads on the wedge tie 18. Since the small face is down, the wedge receive continues pressure from tamped ballast 4. The wedge resists the tamped ballast pressure and the increasingly wider angles maintains pressure on the tamped ballast 4 as well as prevents the ballast from moving upwards. The rolling stock dynamic load arrow pointed downward shows the load being transferred to both the base ballast 2 as well to the tamped ballast 4. The transfer to the tamped ballast 4 effectively increases the foot print size of the wedge tie 18 resulting in load transfer over a larger area, which reduces overall stress the tie 18.
  • FIG. 24 a square shaped tie is modified by adding wedges to the sides in order to create an overall wedge profile;
  • FIG. 25 is a wedge created from trapezoid shape by compensating with large wedges to overcome the upward narrowing of the trapezoid;
  • FIGS. 26 and 27 are a wedge on the bottom of an upper square piece to demonstrate the wedge is not limited to a trapezoidal shape;
  • FIGS. 28 and 29 extend the ideas of FIGS. 26 and 27 to include additional feet that further interlock with tamped ballast 4;
  • FIGS. 30 through 32 are isometric views of the FIGS. 24 through 29;
  • FIGS. 33 and 34 provide more visual details about the wedge shaped tie 18.
  • FIG. 35 is a rectangular NWT tie 11 with a wedge wrap around sole 20. The combination produces an overall wedge profile to retain tamped ballast 4 tight. The overall load transferring profile to the ballast base 2 is reduced due to the increased elastomeric cross section.
  • FIG. 36 is a trapezoid tie 7. In order to create a wedge tie from such a shape, the elastomeric wrap around sole 20 thickness must be increased to compensate for the narrowing trapezoidal shape. Frequent use of the trapezoid shape in industry and pre-existing manufacturing supply makes this shape a viable wedge candidate. Concrete weight and cost are reduced in the trapezoidal shape, yet the overall footprint is large. The addition of a wedge wrap around sole 20 retains tamped ballast 4 tight all the while attenuating wave energies produced by rolling stock and avoiding bottom erosion.
  • FIGS. 37 through 42 depict some possible wrap around sole 19,20 configurations according to the NWT tie 6 cross-sectional shapes.

Claims

1. Reclaimed asphalt 14 is an inexpensive artificial hardpan that reduces tie pumping, reduces debris in ballast 2, and extends rail life and when used in combination with Geotextile 15 placed under reclaimed asphalt hardpan further stabilizes soft areas by distributing forces over larger areas. It reduces tie pumping, and extends rail life and the life of rolling stock rigid components.

2. Automobile tire shreds or tire chips 17 attenuate wave amplitudes, extend rail life, and extend the life of rolling stock rigid components.

3. Elastomeric sole with belting material 13,19,20 protects NWT ties 6 from ballast 2,4 erosion, maintains the tie's original profile, attenuates wave amplitudes and frequencies, grips ballast 2,4, prevents sliding, maintains rail system congruency in three dimensions, reduces pumping, and extends both the life of the rail and rolling stock's rigid components.

4. “Wedge” railroad tie 18,20 maintains tamped ballast 4 locked tight in place, promotes grip between elastomeric sole 19,20 and ballast 2,4, reduces NWT tie 6 erosion, prevents sliding, maintains rail system congruency in three dimensions, reduces pumping, and extends rail life and the life of rolling stock rigid components.