Abstract:
An ultrahigh molecular weight polyethylene material is utilized in a railroad flangeway to reduce the wear of a railroad crossing base.

Description:
CROSS REFERENCE 
   This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/451,592, filed 3 Mar. 2003, entitled “Highway Crossing Flangeway Liner.”This provisional application is incorporated herein as if fully set forth. 

   BACKGROUND 
   1. Field of the Invention 
   The present invention relates to railroad crossings. In particular, the present invention relates to railroad crossing flangeway liners. 
   2. Description of Related Art 
   The railroad industry is constantly working to make railroad crossings safe and effective. In the past, these crossings were made of wood and rubber. Over the years, the railroad industry has upgraded many of these crossings from wood and rubber to concrete. These concrete railroad crossings are typically constructed by securing the rails to either a concrete base or concrete ties and securing concrete panels between the rails. 
   A clearance, called a flangeway, must exist between the inside edge of each rail and the concrete panel to allow for the flanges of the railcar wheels. Steel guard strips are embedded into the top corners of the concrete panels opposite the inside edge of each rail to prevent damage to the concrete panel from the flanges of the railcar wheels. This crossing configuration provides a strong and durable base for the rails, while providing a smooth and stable roadway. The flangeway is typically at least three inches in width. If the flangeway is less than about three inches in width, the inside edges and the flanges of the railcar wheels can impact the steel guard strip causing damage to the concrete panel. If the central concrete panels get damaged, the crossing can become dangerous to both railroad traffic and roadway traffic. In addition, repairing the concrete panels is very costly and time consuming. 
   Although there have been many developments in the area of railroad crossings, many shortcomings remain. 
   SUMMARY OF THE INVENTION 
   There is a need for a railroad crossing in which the flangeway width can be maintained at about three inches or less. 
   Therefore, it is an object of the present invention to provide a railroad crossing in which the flangeway width can be maintained at about three inches or less. 
   This object is achieved by providing a concrete railroad crossing having a flangeway that is lined with ultra high molecular weight polyethylene (UHMWPE). 
   The present invention provides significant advantages over the prior art, including: (1) the UHMWPE liner allows flangeway widths of less than three inches; (2) the UHMWPE liner reduces wear of flangeway components; (3) the UHMWPE liner allows the use of a rubber shock absorber; (4) the UHMWPE liner protects the concrete panel from damage; and (5) the UHMWPE liner allows flangeway widths that are smoother and safer for roadway, pedestrian, and handicapped individual traffic. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross-sectional view of the preferred embodiment of a railroad crossing having a UHMWPE flangeway liner according to the present invention. 
       FIG. 2  is a cross-sectional view of an alternate embodiment of the railroad crossing having a UHMWPE flangeway liner according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1  in the drawings, the preferred embodiment of a railroad crossing  11  having a UHMWPE liner according to the present invention is illustrated in a partial cross-sectional view. For clarity, only one side of railroad crossing  11  is illustrated. It will be appreciated that the other side is a mirror image of the side illustrated. Railroad crossing  11  includes a base  13 , a rail  15 , a rail clip assembly  17 , a central panel  19 , and a liner assembly  21 . Base  13  is a concrete and/or steel substructure, and may be a plurality of concrete railroad ties. Rail  15  is secured to base  13  by rail clip assembly  17 . Central panel  19  is preferably a concrete panel that is disposed between the rails  15 . Central panel  19  preferably includes a blockout portion  23  that extends transversely outward from central panel  19  toward rail  15 . Liner assembly  21  is carried by central panel  19 , preferably at blockout portion  23 . A reinforcement member  25 , preferably a steel angle member, is disposed along the upper outside corner of central panel  19  to provide additional strength to central panel  19 . Central panel  19  may include internal reinforcement members  27 . 
   Liner assembly  21  includes a base portion  31 , a support arm  33 , and a UHMWPE liner  35 . Base portion  31  and support arm  33  are preferably made of rubber or a similar pliable material. Base portion  31  includes a void space  37  for receiving an attachment bar  39  that functions as a washer. Attachment bar  39  includes a plurality of apertures (not shown) that allow attachment bar  31  to be fastened to reinforcement member  25  with conventional fasteners (not shown). Support arm  33  may also include one or more void spaces  41  to provide additional flexibility to support arm  33 . In the preferred embodiment, support arm  33  extends outward from base portion  31  to form a positive seal with rail  15 . Support arm  33  may include a knurled edge  43  to facilitate the sealing of support arm  33  to rail  15 . 
   Liner  35  is preferably a thin strip of UHMWPE that is bonded to an upper vertical edge  45  of base portion  31  by suitable means. Liner  35  is preferably about one-fourth of an inch thick and about one and one-half inches high. Liner  35  preferably extends along the full length of central panel  19  opposite and parallel to rail  15 . The clearance F between the inside edge of rail  15  and the outside vertical edge of liner  35  is defined as a flangeway. The flange of the railcar wheel (not shown) passes through the flangeway as the railcar travels along rail  15 . The pliable nature of base portion  31  allows base portion  31  to absorb impact from the railcar wheels, thereby minimizing damage to central panel  19 . If base portion  31  undergoes excessive wear, damage to central panel  19  is possible. Liner  35  prevents wear of base portion  31 . With UHMWPE liner  35 , the clearance F of the flangeway can be less than three inches while providing sufficient wear protection to base portion  31  and damage protection to central panel  19 . For example, flangeway clearance F can be two and three-fourths inches wide. 
   Referring now to  FIG. 2  in the drawings, an alternate embodiment of railroad crossing  11  having a UHMWPE liner according to the present invention is illustrated in a partial cross-sectional view. For clarity, only one side of railroad crossing  11  is illustrated. It will be appreciated that the other side is a mirror image of the side illustrated. In this embodiment, flat UHMWPE liner  35  is replaced by an angled UHMWPE liner  135 . Also, void space  37  and vertical attachment bar  39  are replaced by a form fitted void space  137  and a horizontal attachment bar  139 . It will be appreciated that the functionality of UHMWPE liner  135 , void space  137 , attachment bar  139 , and the other components of railroad crossing  11  remains unchanged from the preferred embodiment described above. 
   The present invention provides significant advantages over the prior art, including: (1) the UHMWPE liner allows flangeway widths of less than three inches; (2) the UHMWPE liner reduces wear of flangeway components; (3) the UHMWPE liner allows the use of a rubber shock absorber; (4) the UHMWPE liner protects the concrete panel from damage; and (5) the UHMWPE liner allows flangeway widths that are smoother and safer for roadway, pedestrian, and handicapped individual traffic. 
   It is apparent that an invention with significant advantages has been described and illustrated. Although the present invention is shown in a limited number of forms, it is not limited to just those forms, but is amenable to various changes and modifications without departing from the spirit thereof.