Abstract:
A universal boxcar is provided with load carrying capabilities of a conventional uninsulated boxcar and temperature ratings of an insulated boxcar. The insulated boxcar may be formed with interior dimensions corresponding generally with interior dimensions of an uninsulated boxcar without requiring the use of high cost, high performance insulation. The insulated boxcar may be formed at a reasonable cost and selling price with increased load carrying capacity, increased service life, and reduced maintenance costs as compared to conventional insulated boxcars.

Description:
RELATED APPLICATION  
       [0001]     This application claims the benefit of U.S. provisional patent application entitled, “Universal Boxcar”, Application Ser. No. 60/509,935 filed Oct. 9, 2003.  
         [0002]     This application is related to copending patent application entitled “Ceramic/Epoxy Insulated Railway Car”, application Ser. No. 10/682,001, Filed Oct. 9, 2003; copending patent application entitled, “Boxcar With Load Restraint System”, application Ser. No. 10/782,138, filed Feb. 19, 2004, which claims priority from U.S. provisional patent application 60/509,935 filed Oct. 9, 2003 and copending patent application entitled “Universal Boxcar With Exterior Metal Surfaces”, application Ser. No. ______ filed, ______, 2004 which claims priority from U.S. provisional patent application 60/509,935 filed Oct. 9, 2003 
     
    
     TECHNICAL FIELD  
       [0003]     The present invention is related to railway cars and more particularly to insulated boxcars which satisfy applicable AAR requirements for UA factor (heat transfer) and have load carrying capabilities equal to or better than uninsulated boxcars with the same AAR clearance plate.  
       BACKGROUND OF THE INVENTION  
       [0004]     Over the years general purpose boxcars have progressed from relatively simple wooden structures mounted on flat cars to more elaborate arrangements including insulated walls and refrigeration equipment. Various types of insulated and uninsulated boxcars are presently manufactured and used. A typical boxcar includes an enclosed structure mounted on a railway car underframe. The enclosed structure generally includes a floor assembly, a pair of sidewalls, a pair of endwalls and a roof assembly. Insulated boxcars often include sidewalls, endwalls and a roof formed in part by an outer shell, one or more layers of insulation and an interior surface.  
         [0005]     The outer shell of many boxcars may be formed from various types of metal such as steel or aluminum. The interior surfaces may be formed from wood and/or metal as desired for specific applications. For some applications the interior surfaces may be formed from fiber reinforced plastic (FRP). Various types of sliding doors including plug type doors are generally provided on each side of a boxcar for loading and unloading freight.  
         [0006]     The underframe for many boxcars includes a center sill with a pair of end sill assemblies and a pair of side sill assemblies arranged in a generally rectangular configuration corresponding approximately with dimensions of the floor assembly of the boxcar. Cross bearers and/or cross ties may be provided to establish desired rigidity and strength for transmission of vertical loads from the floor assembly to associated side sills which in turn transmit the vertical loads from the floor assembly to associated body bolsters and for distributing horizontal end loads on the center sill to other portions of the underframe. Cross bearers and cross ties generally cooperate with each other to support a plurality of longitudinal stringers. The longitudinal stringers are often provided on each side of the center sill to support the floor assembly of a boxcar.  
         [0007]     Applicable standards of the Association of American Railroads (AAR) established maximum total weight on rail for any railway car including boxcars, freight cars, hopper cars, gondola cars, and temperature controlled railway cars within prescribed limits of length, width, height, etc. All railway cars operating on commercial rail lines in the U.S. must have exterior dimensions which satisfy associated AAR clearance plates. Therefore, the maximum load which may be carried by any railway car is typically limited by the applicable AAR clearance plate and empty weight of the railway car.  
         [0008]     Reducing the empty weight of a railway car or increasing interior dimensions may increase both volumetric capacity and maximum load capacity of a railway car while still meeting applicable AAR standards for total weight on rail and exterior dimensions for applicable AAR clearance plate. Traditionally, insulated boxcars have less inside height and width than desired for cost effective shipment of some types of lading. The maximum exterior width of an insulated boxcar is limited by applicable AAR clearance plates. The maximum interior width is limited by the amount (thickness) of insulation required to satisfy applicable AAR heat transfer limitations or UA factor. Door operating tubes, door bottom tracks and door handles are often built to the extreme width of applicable AAR plate diagrams. Locating door assembly components at the maximum width provides as much interior width as possible for carrying lading within an insulated boxcar or uninsulated boxcar. Door assembly components for many conventional insulated boxcars may extend approximately four inches (4″) from each ride of the boxcar. Therefore, interior dimensions of such boxcars are also limited by the four inch extension of the associated door assemblies.  
         [0009]     Conventional insulated boxcars may have an inside width of nine feet or less while many uninsulated boxcars often have an inside width of approximately nine feet, six inches. Prior insulated boxcars have been relatively ineffective at increasing interior volumetric capacity while maintaining desired UA rating or minimum insulation efficiency required by AAR. UA may be generally described as the number of BTU&#39;s per hour per degree Farenheit which transfer through the roof assembly, sidewall assemblies, endwall assemblies and/or floor assembly of an insulated boxcar.  
         [0010]     At least one insulated boxcar has been built with a nominal length of fifty two feet six inches (52′6″) and an interior width of approximately nine feet six inches (9′6″). This particular insulated boxcar had a UA factor of 285 BTU/° F./hour which is greater than applicable AAR requirements. AAR specifications place various requirements on insulated boxcars such as sidewalls, endwalls, floor and roof having a maximum UA factor of 250 BTU/° F./hour for a fifty foot boxcar and a maximum UA factor of 300 BTU/° F./hour for a sixty foot boxcar.  
         [0011]     Tie down assemblies and cargo anchors are typically located in the floor for many types of boxcars. Some types of lading such as paper products may be damaged by conventional tie down assemblies and anchors in the floor of a boxcar. Also, conventional tie down assemblies and cargo anchors located in the floor of a boxcar may cause problems with cleaning the interior of the boxcar. Some types of lading such as food products have specific requirements for cleaning the interior of a boxcar prior to loading. Water from cleaning or condensation may collect in floor located tie down assemblies and cargo anchors resulting corrosion and increased maintenance costs. The water may also damage paper products, food and other types of lading.  
         [0012]     Typically, conventional boxcars (both insulated and uninsulated) include a pair of sidewall assemblies with substantially the same configuration and dimensions. Such conventional sidewall assemblies generally have approximately the same wall thickness over the length and width of each sidewall assembly. Typically the only change in sidewall thickness occurs at respective openings formed in each conventional sidewall assembly to provide access for loading and unloading of cargo. Sidewall assemblies associated with conventional insulated boxcars often have approximately the same UA factor or heat transfer rating over the length and width of each sidewall assembly.  
       SUMMARY OF THE INVENTION  
       [0013]     In accordance with teachings of the present invention, several disadvantages and problems associated with both insulated and uninsulated boxcars and other types of railway cars have been substantially reduced or eliminated. One embodiment of the present invention includes a dual use or universal boxcar which may satisfactorily carry temperature controlled lading or nontemperature controlled lading. The present invention provides a universal boxcar capable of transporting a wide variety of freight, including frozen products and fresh products which require temperature control and dry food, non-food products and paper products which do not require temperature control.  
         [0014]     An insulated boxcar incorporating teaching of the present invention may provide the load carrying capacity of a conventional uninsulated boxcar and have substantially the same UA factor or heat transfer rating as a conventional insulated boxcar. A universal boxcar incorporating teachings of the present invention may have the same load pattern and load storage capability as a corresponding uninsulated boxcar. The present invention allows maximizing the interior height width of an insulated boxcar while satisfying applicable AAR heat transfer ratings.  
         [0015]     One aspect of the present invention includes providing an insulated boxcar with steel interior surfaces satisfactory for carrying lading such as coiled steel, lumber, beer, wine, any other liquid filled containers, newsprint, paper rolls, automobile parts, household appliances, electronic equipment, canned food products and/or packaged food products (both perishable and non-perishable). For some applications the interior surfaces may be coated with ceramic/epoxy insulating materials having a plurality of microspheres. Ceramic bead infused epoxy coatings are one example of such insulating materials.  
         [0016]     The present invention allows designing sidewall assemblies and endwall assemblies with reasonably priced insulating materials having optimum thickness to minimize heat transfer rates (UA factor) between the interior and the exterior of the sidewall assemblies and endwall assemblies while maximizing interior load carrying capacity. For some applications, insulators may be disposed between selected components of each sidewall assembly and associated side sill to satisfy applicable heat transfer ratings. Structural integrity of an insulated boxcar may be maintained using conventional materials such as steel alloys or aluminum alloys to form interior portions and supporting structures of the sidewall assemblies and endwall assemblies. An exterior shell of fiber reinforced plastic or other suitable, lightweight materials may be used to reduce empty car weight of the boxcar. The present invention provides an insulated boxcar with increased insulation efficiency and satisfactory heat transfer rates without the use of expensive, exotic insulation materials and at the same time satisfying all applicable AAR specifications.  
         [0017]     The present invention allows tie down assemblies and anchors associated with many conventional boxcars to be removed from the floor to improve heat transfer characteristics. Tie down assemblies and anchors may be attached to or formed as components of structural members associated with each sidewall assembly in accordance with teachings of the present invention. Placing anchors and tie down assemblies in adjacent sidewall assemblies allows improved cleaning of an associated floor and provides a generally smooth floor surface satisfactory for carrying lading such as paper rolls or any other lading which may be damaged by conventional tie down assemblies and anchors located in a floor.  
         [0018]     Technical benefits of the present invention include placing cargo anchors or tie down assemblies in adjacent sidewall assemblies to prevent retention of water from condensation or wash out during cleaning from being retained within the anchors or tie down assemblies. Conventional anchors or tie down assemblies which are placed in the floor of a conventional boxcar often rust and prematurely fail as a result of corrosion associated with water retained within the respective cargo anchor or tie down assemblies. Also, moisture trapped in conventional cargo anchors or tie down assemblies located in the floor of a boxcar may damage or contaminate commodities such as paper and food products.  
         [0019]     Tie down assemblies and cargo anchors attached to a sidewall assembly in accordance with teachings of the present invention may have substantially increased load carrying capacity as compared with prior sidewall tie down assemblies or anchors. For example floor anchors associated with conventional boxcars may be used to restrain loads weighing thirty thousand pounds (30,000 lbs.). Conventional sidewall anchors are often not able to support this much load. Tie down assemblies and cargo anchors formed in accordance with teachings of the present invention may be used to satisfactorily restrain thirty thousand pound steel coils while eliminating or reducing potential risk of corrosion and maintaining desired thermal efficiency.  
         [0020]     Further technical benefits of the present invention include providing a double seal assembly for doors associated with insulated boxcars. The use of a double seal assembly between a door and an adjacent frame assembly substantially reduces heat transfer when the door is in its closed position. Conventional insulated boxcars often include a single door seal gasket. When a single seal gasket becomes worn or torn, air may communicate through the damaged seal resulting in heat transfer rates greater than allowed by AAR specifications. A second seal formed in accordance with teachings of the present invention improves the life and durability of the door seal system and provides an added thermal barrier by trapping air between the first seal and the second seal. The second seal may have various configurations shapes such as a “shark tooth” shape, round shape or other conventional seal shapes. The second seal may be mounted all around the entire perimeter of the door or parallel with the existing first door gasket seal. A double seal assembly formed in accordance with teachings of the present invention provides improved insulation as well as a redundant seal in the event of failure of one of the seal mechanisms.  
         [0021]     Technical benefits of the present invention include providing an insulated boxcar having an increased interior height and width while maintaining maximum height and exterior width of the boxcar within limits prescribed by the American Association of Railroads. Sidewalls and endwalls may be formed in accordance with teachings of the present invention using insulation materials which provide desired thermal heat transfer characteristics at a reasonable cost. For some application, extra urethane foam insulation may be added by increasing sidewall thickness in areas where an associated door assembly does not operate.  
         [0022]     Door operating tubes, handles and the bottom of the door track are preferably built to the maximum width for a boxcar in accordance with applicable AAR specifications to provide the maximum available interior width for load carrying capability. The door and door track area is often cover approximately forty percent of the exterior surface of each sidewall assembly. To meet AAR heat transfer requirements, the thickness of selected portions of each sidewall assembly may be increased to the maximum allowed AAR width of the associated boxcar. The thickness of insulation may be substantially increased in any portion of a sidewall assembly which is not associated with operation of a respective door assembly As a result, approximately three inches of insulation may be added to approximately sixty percent of available sidewall area for many boxcars. The present invention provides increased sidewall insulation thickness while at the same time providing for increased interior width of the cargo carrying capacity.  
         [0023]     AAR regulations require insulated boxcars to have an insulation efficiency or UA (factor) of three hundred or lower for a sixty foot long boxcar. To achieve the required UA factor, four inches or more of insulation are typically required in the sidewall. Insulated boxcars formed in accordance with teachings of the present invention preferably include additional insulation in portions of each sidewall which are not used or associated with operation of the respective door assembly. Depending upon materials used to form an insulated boxcar in accordance with teachings of the present invention the associated UA rating may be between approximately 200 and 300.  
         [0024]     For some applications, a composite box structure may be formed in accordance with teachings of the present invention with sidewall assemblies, endwall assemblies and a roof assembly having respective exterior surfaces formed from fiber reinforced plastic or any other suitable materials.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]     For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following written description taken in conjunction with the accompanying drawings, in which:  
         [0026]      FIG. 1  is a schematic drawing in elevation showing a side view of an insulated boxcar incorporating teachings of the present invention;  
         [0027]      FIG. 2  is a schematic drawing in section with portions broken away showing a floor assembly, sidewall assemblies and endwall assemblies incorporating teachings of the present invention;  
         [0028]      FIG. 3  is a schematic drawing in section with portions broken away showing one example of an insulating coating disposed on interior surfaces of an insulated boxcar incorporating teachings of the present invention;  
         [0029]      FIG. 4  is a schematic drawing in section with portions broken away taken along limes  4 - 4  of  FIG. 2  showing one example of variations in thickness of sidewall assemblies incorporating teachings of the present invention;  
         [0030]      FIG. 5  is a schematic drawing in section with portions broken away showing one example of joining a roof assembly with relatively thick portions of a sidewall assembly in accordance with teachings of the present invention;  
         [0031]      FIG. 6  is a schematic drawing in section with portions broken away showing one example of joining a roof assembly with relatively thin portions of a sidewall assembly and components of a door assembly in accordance with teachings of the present invention;  
         [0032]      FIG. 7  is a schematic drawing in section with portions broken away showing one example of a floor assembly, a sidewall assembly and a side sill incorporating teachings of the present invention;  
         [0033]      FIG. 8  is a schematic drawing showing an isometric view with portions broken away of a cargo anchor system disposed in a sidewall assembly in accordance with teachings of the present invention;  
         [0034]      FIG. 9  is a schematic drawing in section with portions broken away showing one example a double seal assembly satisfactory for use with a insulated boxcar incorporating teachings of the present invention;  
         [0035]      FIG. 10A  is a schematic drawing in elevation with portions broken away showing an interior surface of an endwall assembly incorporating teachings of the present invention;  
         [0036]      FIG. 10B  is a schematic drawing in section taken along lines  10 B- 10 B of  FIG. 10A ;  
         [0037]      FIG. 11  is a schematic drawing in section with portions broken away showing a corner joint or corner connection formed between a sidewall assembly and an endwall assembly incorporating teachings of the present invention; and  
         [0038]      FIG. 12  is a schematic drawing with portions broken away showing a plan view of a roof assembly incorporating teachings of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0039]     Preferred embodiments of the invention and its advantages are best understood by reference to  FIGS. 1-12  of the drawings, like numerals are used for like and corresponding parts in the various drawings.  
         [0040]     The term “boxcar” often refers to a railway car having a generally elongated box type structure defined in part by a roof assembly, a floor assembly, a pair of sidewall assemblies, and a pair of endwall assemblies which cooperate with each other to define a generally hollow interior satisfactory for carrying various types of lading. The terms “boxcar” and “box car” may be used in this application to refer to both insulated and uninsulated boxcars.  
         [0041]     The term “insulated boxcar” is used in this application to refer to a boxcar formed at least in part with insulating materials to minimize heat transfer through associated sidewall assemblies, endwall assemblies, roof and/or floor. Insulated boxcars do not generally include refrigeration systems or temperature control systems. The AAR has several different classes of insulated boxcars such as VM—partially insulated fruit, vegetable ventilated box; VS—insulated fruit, vegetable ventilated box and LRC—heavily insulated boxcar for solid carbon dioxide.  
         [0042]     The terms “tie down assembly”, “anchor” and “cargo anchor” may be used in this application to refer to any device, mechanism or assembly operable to secure lading at a desired location within a boxcar.  
         [0043]     Various aspects of the present invention will be described with respect to insulated boxcar  20 . However, the present invention is not limited to insulated boxcars. For example, some features of the present invention may be satisfactorily used to form uninsulated boxcars, temperature controlled railway cars, refrigerated boxcars and any other type of railway car having at least one sidewall assembly and a floor assembly mounted on a railway car underframe. A boxcar may be formed in accordance with teachings of the present invention to accommodate various geometric configurations and load carrying requirements to satisfy specific customer needs concerning size and temperature specifications for different types of lading. Examples of such lading include, but are not limited to, coiled steel, lumber, electronic equipment, automobile parts, household appliances, paper, paper products, household goods, nonperishable food products and any other product suitable for transport in a boxcar and does not require temperature control. Further examples of such lading include, but are not limited to, liquid filled containers, perishable food products (fresh, canned and packaged) and any other product suitable for transport in a boxcar and requires temperature control.  
         [0044]     The present invention allows insulated boxcar  20  to have flexible loading capability to improve potential for carrying back-haul loads. Insulated boxcar  20  may be used to carry lading associated with both insulated and uninsulated boxcars and may sometimes be referred to as a “universal” boxcar. In the past, materials, configuration, size and components of conventional insulated boxcars often limited their ability to be effectively used to carry lading associated with uninsulated boxcars. To accommodate cargo that would typically be shipped using an uninsulated boxcar, insulated boxcar  20  includes metal interior surfaces, cargo anchors and a large interior volume equal to or greater than many uninsulated boxcars while meeting or exceeding requirements published by the AAR for insulated boxcars.  
         [0045]     Insulated boxcar  20  incorporating teachings of the present invention is shown in  FIG. 1  with box structure  30  mounted on railway car underframe  200 . For some applications, insulated boxcar  20  may be modified to include a temperature control system (not expressly shown) and an airflow management system (not expressly shown). For embodiments of the invention as shown in  FIGS. 1-11 , insulated boxcar  20  may have a nominal length of sixty feet, exterior dimensions which satisfy the Association of American Railroads (AAR) Plate F clearance requirements and associated AAR design and heat transfer requirements. Insulated boxcar  20  is only one example of a universal boxcar which may be formed in accordance with teachings of the present invention.  
         [0046]     Box structure  30  may be formed from various components including roof assembly  40 , sidewall assemblies  150  and  152 , floor assembly  80  and endwall assemblies  120  and  122 . For some applications, roof assembly  40  may have a width of approximately nine feet. Forming various components of box structure  30  in accordance with teachings of the present invention on railway car underframe  200  may result in reducing the empty weight of insulated boxcar  20  while at the same time increasing both interior volume (interior height and width) and load carrying capacity as compared to many conventional insulated boxcars with the same AAR Plate F clearance and UA factor. For some applications insulated boxcar  20  may have the same or larger interior volume and load carrying capacity as compared to uninsulated boxcars satisfying AAR Plate F clearance requirements.  
         [0047]     For embodiments of the present invention as shown in  FIGS. 1-11  portions of railway car underframe  200  may be manufactured and assembled using conventional railcar manufacturing procedures and techniques. Railway car underframe  200  preferably includes a pair of railway car trucks  202  and  204  located proximate each end of railway car underframe  200 . Standard railcar couplings  210  are also provided at each end of railway car underframe  200 . Each coupling  210  preferably includes respective end of car cushioning unit  212  disposed at each end of center sill  214 . Hand brake  208  may be mounted on one end of railway car underframe  200 . Ladders  206  may be mounted on exterior portions of sidewall assemblies  150  and  152  adjacent to endwall assemblies  120  and  122 . See  FIGS. 1, 3 ,  4  and  11 .  
         [0048]     Railway car underframe  200  includes a pair of body bolsters (not expressly shown) with each body bolster disposed over respective railway trucks  202  and  204 . The body bolsters may extend laterally from center sill  214 . For some applications, each body bolster includes cover plates (not expressly shown) which extend over the wheels of railway car trucks  202  and  204 . Railway car underframe  200  may include center sill  214 , longitudinal stringers  230 , cross bearers and/or cross ties  216 , body bolsters and side sill assemblies  250  and  252  arranged in a generally rectangular configuration. Cross bearers  216  are attached to and extend laterally from center sill  214 .  
         [0049]     Railway car underframe  200  preferably includes a plurality of longitudinal stringers  230  which extend approximately the full length of railway car underframe  200  parallel with center sill  214 . Longitudinal stringers  230  may be disposed on cross bearers  216 ,  FIGS. 3, 4  and  7  show portions of floor assembly  80  disposed on longitudinal stringers  230  and respective portions of side sill assemblies  250  and  252 . The number of cross bearers and/or cross ties  216 , and longitudinal stringers  230  may be varied depending upon desired load carrying characteristics for the resulting insulated boxcar  20 .  
         [0050]     Each longitudinal stringer  230  preferably includes first surface  231  and second surface  232  which rests upon cross bearers  217  and cross ties  216 . See  FIG. 7 . A selected portion of floor assembly  80  may be adhesively bonded or securely attached with portions of first surfaces  231  of longitudinal stringers  230 .  
         [0051]     Sidewall assemblies  150  and  152  may be fabricated with respective side sill assemblies  250  and  252  formed as integral components thereof. Endwall assemblies  120  and  122  may also be formed with all or at least portions of respective end sill assemblies (not expressly shown) formed as integral components thereof. Side sill assemblies  250  and  252  may have substantially the same overall configuration and dimensions. As shown in  FIGS. 3, 4  and  7  side sill assemblies  250  and  252  may have a generally C shaped cross section.  
         [0052]     Portions of the roof assembly  40 , floor assembly  80 , sidewall assemblies  150  and  152  and/or endwall assemblies  120  and  122  may be formed from conventional materials such as steel alloys and/or other metal alloys used to manufacture railway cars. Portions of the roof assembly  40 , floor assembly  80 , sidewall assemblies  150  and  152  and/or endwall assemblies  120  and  122  may also be formed with insulating materials such as urethane foam and polyvinyl chloride blocks. Closed cell urethane foams are often used in insulated boxcars. Examples of some materials which may be used to form an insulated boxcar incorporating teachings of the present invention are discussed throughout this application.  
         [0053]     For some applications, roof assembly  40  may have an exterior layer  51  formed at least in part from fiber reinforced plastic and an interior layer  52  formed at least in part from fiber reinforced plastic. Various features associated with roof assembly  40  will be discussed later in more detail.  
         [0054]     Various components associated with box structure  30  may be fabricated individually and then attached to or mounted on railway car underframe  200  to form insulated boxcar  20 . Individually manufacturing or fabricating various components of box structure  30  may allow optimum use of conventional railcar manufacturing techniques. Alternatively, one or more of the components associated with box structure  30  may be fabricated and assembled on railway car underframe  200  to allow optimum use of conventional railcar manufacturing techniques.  
         [0055]     As shown in  FIGS. 1-4  the thickness of each sidewall assembly  150  and  152  may vary along the length of each sidewall assembly extending between endwall assembly  120  and endwall assembly  122 . Conventional sidewall assemblies often have a generally symmetrical configuration with respect to each other and other components of an associated railway car. Sidewall assemblies formed in accordance with teachings of the present invention may have a nonsymmetrical configuration as a result of variations in thickness along the length of each sidewall assembly.  
         [0056]     For embodiments of the present invention as shown in  FIGS. 1-4  sidewall assembly  150  may include first portion  150   a , second portion  150   b  and third portion  150   c . Opening  154  may be formed between first portion  150   a  and  150   b . Opening  154  is preferably sized to receive door assembly  180  which controls access to interior  32  of composite box structure  30 . The size of opening  154  may be varied to accommodate a wide variety of loading and unloading requirements. For example, opening  154  may accommodate a door height of twelve feet four inches.  
         [0057]     As discussed later in more detail first portion  150   a  and third portion  150   c  may have an increased thickness to accommodate additional insulation materials. Second portion  150   b  may have a reduced thickness to accommodate movement of associated door assembly  180  between its first, closed position as shown in  FIG. 1 , and a second, open position (not expressly shown). Sidewall assembly  152  may also include first portion  152   a  with an increased thickness, second portion  152   b  with a reduced thickness and third portion  152   c  with an increased thickness. As shown in  FIG. 2  the arrangement of portions  152   a ,  152   b  and  152   c  is substantially reversed as compared with sidewall assembly  150 .  
         [0058]     Each sidewall assembly  150  and  152  may be formed with interior metal surfaces  162  and exterior surfaces or skin  172  of fiber reinforced plastic or other lightweight materials. Conventional insulating materials such as urethane foam  164  may be disposed between and bonded with the interior and exterior surfaces. Sidewall assemblies  150  and  152  may be formed from a plurality of support posts  156 , interior layers formed from metal plates or metal sheets  160  and exterior layers  170  formed from fiber reinforced plastic (Fiberglass® for some applications) or any other suitable materials. Metal plates  160  cooperate with each other to provide interior surface  162  of each sidewall assembly  150  and  152 . Exterior layers  170  cooperate with each other to form exterior surface  172  of each sidewall assembly  150  and  152 .  
         [0059]     Exterior layer  170  may be formed from various types of material such as thin sheets of fiber reinforced plastic or any other suitable materials. Exterior layer  170  provides a cover or protective sheath for insulation material  164 . Respective beams  166  may be attached to the exterior surface or second surface of each support post  156  opposite from metal plates  160 . For some applications beams  166  may be formed from polyvinyl chloride (PVC) type materials and may have the general cross section of an I beam. Beams  166  may also be formed from pultruded fiber reinforced plastics.  
         [0060]     As shown in  FIG. 8 , metal plate or metal sheet  160  may be attached with the first surface or interior surface  157  of each support post  56 . Respective beams  166  may be bonded with or attached to the second surface  158  of each support post  156 . Fiber reinforced plastic layer  170  may then be bonded with each beam  166  opposite from respective support post  156 . Urethane foam  164  may be injected or poured into void spaces defined in part by metal sheets  160 , support post  156 , beams  166  and layer  170 . For some applications, blocks  168  may be disposed within each sidewall assembly to aid in maintaining at a desired location during solidification. See  FIGS. 7 and 8 .  
         [0061]     For some application rolls of relatively thin Fiberglass® sheets may be used to form exterior layer  170  on each sidewall assembly  150  and  152 . The thickness may vary from one eighth of an inch to one fourth of an inch. The respective layers of fiberglass may partially overlap each other to cover substantially the full length and height of each sidewall assembly  150  and  152 . For some applications a pour type urethane foam may be injected into void spaces between metal sheets  160  and exterior layer  170 . Pour foam may generally be injected faster into such void spaces and will generally cure faster as compared to other types of urethane foam.  
         [0062]     Since pour foam often experiences higher pressures while curing, sidewall assemblies  150  and  152  and endwall assemblies  120  and  122  will generally be placed in appropriate fixtures (not expressly shown) during the curing process. After sidewall assemblies  150  and  152 , endwall assemblies  120  and  122  and roof assembly  40  have been mounted on and attached to railway car underframe  200 , froth foam may be added to or sprayed into and remaining void spaces. Froth foam may also be applied to various portions of railway car underframe  200  opposite from floor assembly  80 . Pour type urethane foam may be obtained from various suppliers including, but not limited to, Carpenter Company. Froth foam may also be obtained from various suppliers including, but not limited to, Foam Supplies, Inc. For some applications, foam blocks or isolators may be used to attach exterior layer  170  with second surface or exterior surface of support posts  156 . The foam blocks or isolators may be formed from various materials such as polyvinyl chloride. Urethane foam blocks may also be used.  
         [0063]     Sidewall assemblies  150  and  152  preferably includes a plurality of metal side sheets  160  disposed on the interior thereof. Each side sheet  160  may include first surface  161  and second surface  162 . First surface  161  of side sheets  160  cooperate with each other to form a portion of the interior surfaces of box structure  30 . For one application side sheets  160  may be formed from twelve (12) gauge steel. See  FIGS. 5B and 8 .  
         [0064]     A plurality of side stakes or support posts  156  are preferably attached to second surface  162  of each side sheet  160 . Each side stake  156  may include first surface  157  and second surface  158 . First surface  157  of each side stake  156  may project toward interior  32  of box structure  30 . For some applications, isolators or beams  166  formed from an insulating material such as polyvinyl chloride (PVC) may be attached to second surface  158  of each support post  156 . Exterior layer  170  may be bonded with isolators  166  opposite from support posts  156 . Various types of blocks and/or strips of insulating materials may be satisfactorily used to couple exterior layer  170  with respective support post  156 .  
         [0065]     For some applications beams  166  may be formed from urethane foam. Placing isolators  166  between support post  156  and adjacent portions of exterior layer  170  provides sufficient structural strength for exterior layer and minimizes heat transfer through support post  156  between the interior and exterior of box structure  30 . The present invention is not limited to use of PVC strips, PVC blocks, or any type of isolators.  
         [0066]     The configuration and dimensions of sidewall assemblies  150  and  152  are preferably compatible with of AAR Clearance plate F represented by dotted lines  34 ,  36  and  38 . Dotted lines  34  and  36  as shown in  FIG. 2  represent applicable AAR clearance plate dimensions for boxcar  20 . Dotted lines  38  as shown in  FIGS. 4-7  also represent applicable AAR clearance plate dimensions.  
         [0067]     Respective support members  256  may be attached to interior surface  258  of each side sill assembly  250  and  252 . Support members  256  may extend along substantially the full length of the respective side sill assemblies  250  and  252 . For the embodiment of the present invention as shown in  FIGS. 4 and 7  support members  256  may be formed from metal angles having desired dimensions compatible with railway car underframe  200  and floor assembly  80 . Support members  256  may be welded with or otherwise securely attached with adjacent portions of side sill assemblies  250  and  252 . Support members  256  form portions of respective connections or longitudinal joints between the lower portion of each sidewall assembly  150  and  152  and adjacent portions of floor assembly  80 . See  FIGS. 4 and 7 .  
         [0068]     For some applications froth foam may be injected into void spaces formed between roof assembly  40  and respective sidewall assemblies  152  and  150 . See  FIGS. 4-7 . In  FIG. 5  froth foam may be injected into void space  174  formed between roof assembly  40  and sidewall assembly  152 . A pultruded and/or extruded strip of fiber reinforced plastic  176  may be used to cover void space  174 . Portions of exterior layers  51  associated with roof assembly  40  preferably overlap or cover a portion of each extruded panel  176 . In a similar manner a portion of each extruded panel  176  preferably overlaps respective layer  170  of sidewall assemblies  152  and  150 .  
         [0069]     Endwall assemblies  120  and  122  may be formed using similar materials and techniques as previously described with respect to sidewall assemblies  150  and  152 . For sidewall assemblies  150  and  152 , support posts  156  extend generally vertically between respective side sill assemblies  250  and  252  and roof assembly  40  (see  FIGS. 3 and 4 ). Endwall assemblies  120  and  122  may be formed with end beams  126  having an I-beam configuration. However, end beams  126  disposed within endwall assemblies  120  and  122  extend generally horizontally with respect to each other and railway car underframe  200 . Each endwall assembly  120  and  122  preferably includes a respective top chord or top plate  134  attached with upper portions of adjacent metal sheets  124 . See  FIGS. 10A and 10B .  
         [0070]     Metal sheets  124  may be attached to first surface  126   a  of each end beam  126 . Metal sheets  124  of endwall assemblies  120  and  122  may also be referred to as “end sheets.” Respective isolators  128  formed from insulating materials may be attached to second surface  126   b  of each end beam  126 . Exterior layers  130  formed from fiber reinforced plastic or other lightweight material may be attached to isolators  128  opposite from end beams  126 . Exterior layers  130  cooperate with each other to form exterior surface  132  of each endwall assembly  120  and  122 .  
         [0071]     Foam insulation may be disposed between and bonded with adjacent portions of end beams  126 , metal sheets  124  and adjacent portions of exterior layer  130 . For one embodiment endwall assembly  120  may be preferably mounted on the first end or A end may be of railway car underframe  200 . In a similar manner, endwall assembly  122  may be mounted on the second end or B end of railway car underframe  200 .  
         [0072]     As previously noted, roof assembly  40 , sidewall assemblies  150  and  152 , floor assembly  80 , and endwall assemblies  120  and  122  may be fabricated as individual components. For some applications these components may be fabricated at the same facility. For other applications one or more components may be fabricated at a remotely located facility. Each component may be attached to railway car underframe  200  in accordance with teachings of the present invention.  
         [0073]     For one embodiment sidewall assembly  150  is preferably mounted on one longitudinal edge of railway car underframe  200  with side sill assembly or bottom chord  250  disposed adjacent to associated ends of cross bearers or cross beams  216 . In a similar manner sidewall assembly  152  may be mounted on an opposite longitudinal edge of railway car underframe  200  with side sill assembly or bottom chord  252  disposed adjacent to associated ends of cross bearers or cross beams  216 . Various types of mechanical fasteners and/or welds may be formed between side sill assemblies  250  and  252  and the respective ends of cross bearers or cross beams  216 . For some applications Huck type mechanical fasteners are preferably used to attach side sill assemblies  250  and  252  with the respective cross bearers and/or cross beams  216 .  
         [0074]     Sidewall assemblies  150  and  152  preferably include respective top chords  178 . Top chords  178  generally extend longitudinally along the respective upper edge of sidewall assemblies  150  and  152 . Each top chord  178  may have a cross section defined by a generally “W-shaped” portion with leg  179  extending therefrom. The upper portion of adjacent side sheets  160  may be attached with the W portion of each of the associated top chord  178 . See  FIGS. 5 and 6 . Various techniques such as welding and/or mechanical fasteners may be used to attached metal sheets  160  with adjacent portions of top chords  178 .  
         [0075]     Roof assembly  40  may be formed with a generally elongated, rectangular configuration. The length and width of roof assembly  40  corresponds generally with the desired length and width of box structure  30 . Roof assembly  40  includes first longitudinal edge  41  and second longitudinal edge  42  spaced from each other and extending generally parallel with each other from first lateral edge  43  to second lateral edge  44 . First longitudinal edge  41  and second longitudinal edge  42  are preferably mounted on and attached with adjacent portions of respective sidewall assemblies  150  and  152 . See  FIGS. 5 and 6 . Lateral edges  43  and  44  are preferably mounted on and attached with respective endwall assemblies  120  and  122 . End wall assemblies may have a four inch flap  129  which folds over respective lateral edges  43  and  44 . See  FIGS. 10A and 10B .  
         [0076]     Various types of composite materials, insulating materials and metal alloys may be satisfactorily used to form roof assembly  40 . For some applications roof assembly  40  may include septum or layer  50  disposed between exterior layer  51  and interior layer  52 . See  FIGS. 3, 5A ,  6  and  12 . Septum  50  of roof assembly  40  may include a plurality of metal sheets or metal plates  54  extending between and connected with respective top chords  178  associated with sidewall assemblies  150  and  152 . For embodiments such as shown in  FIG. 12 , two metal sheets  54  may be disposed adjacent to each endwall assembly  120  and  122 . Also, six metal sheets  54  may be disposed adjacent to the openings associated with door assemblies  180 . These selected locations may correspond with generally high stress areas. Metal sheets  54  may act as plate girders to help stiffen composite box structure  30  with respect to racking and torsional loads. Metal plates  54  may be formed from fourteen (14) gauge steel sheets. For one application metal plates  54  may have approximate dimensions of three feet then inches by nine feet four inches.  
         [0077]     A plurality of beams  56  may be disposed between and securely engaged with top chord  178  of sidewall assembly  150  and top chord  178  of sidewall assembly  152 . Ends  58  of each beam  56  may be notched or otherwise configured for engagement with the associated top chord  178 . See  FIGS. 5A and 6 . In addition to notches  58 , generally triangular shaped gussets  59  may be attached to each end of beams  56 . Gussets  59  may be formed from the same material as beams  56 . Notches  58  and associated gussets  59  allow forming appropriate welds with adjacent top chords  176 . Notches  58  also help to provides desired inside height while maintaining the desired door height and desired insulation thickness (at least four inches) for roof assembly  40 .  
         [0078]     Various types of beams  56  may be used to form roof assembly  40 . The configuration of beams  56  may vary along the length of roof assembly  40 . For some applications beams  56   a  may have a generally hat shaped cross section to accommodate attachment of metal plates  54 . For one application beams  56   a  may be formed from fourteen gauge steel with nine inch (9″) flanges. For embodiments such as shown in  FIG. 11 , beams  56   a  may be disposed proximate each end of roof assembly  40  and adjacent to door assemblies  180 . For some applications, beams  56  may be formed from hollow steel tubes. For one application beams  56  may have a generally square, three inch cross section. Beams  56  may be formed from steel alloys, aluminum alloys or any other material satisfactory for forming roof assembly  40 .  
         [0079]     For some applications, a plurality of blocks  62  may be disposed between support beams  56  and adjacent portions of exterior layer  52 . Blocks  62  may be formed from PVC foam or other suitable insulating materials. Various types of adhesives (not expressly shown) may be used to attach blocks  62  with support beams  56  and exterior layer  51 . A plurality of fiber reinforced pultrusions  64  may also be attached to exterior layer  51  and extend longitudinal along roof assembly  40 . See  FIGS. 5A and 6 . Pultrusions  64  may have a generally hollow, square cross section of one inch by one inch with a wall thickness of approximately 0.1 inches. Pultrusions  64  help to reinforce exterior layer  52 .  
         [0080]     Interior layer  52  may be formed from graffiti resistant, pigmented fiber reinforced plastic. For some applications interior layer  52  may be formed from tough, lightweight, relatively rigid material having high impact resistance available from U.S. Liner Company, a division of American Made, Inc. under the trademark Bulitex®. Bulitex® material may be generally described as a ballistic grade composite scuff and wall liner.  
         [0081]     Exterior layer  51  may be formed from white fiber reinforced plastic with an opaque UV coating. Various types of protective coating such as Armor-Tuff® may also be applied to layers  51  and  52 . Urethane foam blocks (not expressly shown) may be disposed between beams  56  and layers  51  and  52 . For one application, the foam blocks may be approximately four inches thick, nine feet long and sixty-one inches wide. Nine feet corresponds with the approximate width of roof assembly  40 . Sixty-one inches corresponds with approximate spacing between support beams  56 .  
         [0082]     Roof assembly  40  may be attached to and/or bonded with respective top chords  178  of sidewall assemblies  150 ,  152  and top chords or top plates  134  of endwall assemblies  120  and  122 . Insulating foam is preferably disposed within the joint or flexible connection formed between roof assembly  40  and adjacent portions of sidewall assembly  150 . Trim molding may be bonded with adjacent portions of roof assembly  40  and sidewall assemblies  150  and  152 .  
         [0083]     Each sidewall assembly  150  and  152  preferably includes respective openings  154  with door assembly  180  attached thereto and slidably mounted thereon. See  FIGS. 1 and 2 . Each door assembly  180  has a first position blocking respective opening  154  to form a barrier between interior  32  and the exterior of box structure  30 . Each door assembly  180  also has a second position which allows access to interior  32  of box structure  30  through respective opening  154 . Various types of doors may be satisfactory used with box structure  30 , including doors fabricated from steel and/or wood, or doors fabricated from composite materials. Door assembly  180  is preferably formed from materials with thermal insulation characteristics corresponding with the associated sidewall assembly  150  and  152 . Each door assembly  180  is preferably mounted on respective sidewall assemblies  150  and  152  adjacent to respective portion  150   b  and  152   b  using conventional hardware such as operating pipes, operating mechanisms, rollers, locking bars, gears and cams associated with conventional railway boxcars. Such items may be obtained from several vendors including YSD Industries, Inc. (Youngstown Steel Door), and Pennsylvania Railcar.  
         [0084]     Each door assembly  180  may be slidably mounted on upper track  194  and lower track  196  which are attached adjacent to respective openings  36 . Door frame assembly  190  may include upper track  194  and portions of top chord  178 . Upper track  194  is shown attached with adjacent portions of top chord  178 . One or more layers  196  of sealing material may be disposed between upper track  194  and leg  179  of top chord  178 . Various welding techniques and/or mechanical fasteners may be used as desired.  
         [0085]     Door frame assembly  190  is preferably attached to the perimeter of each opening  154  formed in respective sidewall assemblies  150  and  152 . Each door frame assembly  190  may include a pair of vertical door post assemblies  191  and door header or door retainer  192 . Upper door track  194 , lower door track  196 , and a threshold (not expressly shown) may also be installed adjacent to each door frame assembly  190 . Vertical door post assemblies  191  are attached with an secured to adjacent portions of sidewall assemblies  150  and  152 . Door header  192  is disposed between and attached to vertical door post assemblies  191  at the top of each opening  36 .  
         [0086]     Metal plates (not expressly shown) and/or an elastomeric threshold may be disposed within the lower portion of each opening  154  adjacent to floor assembly  80 . The metal plates and/or threshold may be formed from steel alloys, aluminum alloys, ceramic materials and/or composites of these materials.  
         [0087]     A pair of elastomeric gaskets may be formed on the interior of each door port assembly  190  adjacent to the perimeter of the respective door assembly  180 . See  FIG. 9 . The elastomeric gaskets preferably form contacts with two portions of door assembly  180  when the respective door  180  is in its first position. The elastomeric gaskets and portions of door frame assembly  190  cooperate with each other to minimize heat transfer between the interior and the exterior of box structure  30 , when the respective door  180  is in its first, closed position. Door stops (not expressly shown) may be mounted on the exterior of each sidewall assembly  150  and  152  to limit movement of the associated door assembly  180  from its first position to its second position.  
         [0088]     Various types of mechanical tie-down connections may be provided within interior  32  of box structure  30 . The tie down assemblies and/or cargo anchor assemblies are preferably attached with portions of sidewall assemblies  150  and  152 . Floor assembly  80  preferably has a generally smooth uniform surface without any tie down assemblies and/or cargo anchor assemblies. As shown in  FIGS. 7 and 8  a plurality of openings  258  may be formed in each longitudinal member  256 . A respective enclosure  260  may be bonded with and attached to respective support post  156 . For some embodiments of the present invention such as shown in  FIGS. 7 and 8 , enclosures  260  have a generally U-shaped, hollow configuration. During clean out of box structure  30  enclosures  260  prevent water or other fluids coming in contact with the foam insulation disposed between exterior layer  170  and metal sheets  160 . U.S. Pat. No. 6,494,651 entitled “Railcar Anchor and Load Snugger Arrangement” shows one example of load restraining anchor assemblies which may be releasably engaged with respective openings or holes  258  at desired locations within box structure  30 .  
         [0089]     The door seal assembly shown in  FIG. 9  may include a conventional door gasket or seal  192 . An additional door gasket or seal  194  having the general configuration of a “sharks tooth” may also be provided. For some applications conventional door gasket or seal  192  may be permanently attached with adjacent portions of door assembly  190 . Additional door gasket  194  may be permanently attached with adjacent portions of vertical support post  191 . However, the location and arrangements of door gaskets and seals  192  and  194  may be buried as desired for each type of insulated boxcar.  
         [0090]     For some applications foam blocks or wood blocks  168  may be disposed beneath each side sill assembly  250  and  252  for use in maintaining insulating foam at a desired location while during fabrication of the respective sidewall assembly  150  and  152 .  FIGS. 7 and 8  show examples of blocks  168  formed from wood or PVC type materials which may be satisfactorily used when injecting insulating foam into these areas.  
         [0091]     Hucks and other types of mechanical fasteners such as shown in  FIGS. 7 and 8  may be satisfactorily used to attach support posts  156  with adjacent portions of side sill assemblies  250  and  252 . Various types of isolators including, but not limited to, fiber reinforced plastic pultrusions may be installed at mechanical connections between sidewall assemblies  150  and  152  and adjacent portions of railway car underframe  200  to reduce thermal leakage. Such isolators may also be installed between endwall assemblies  120  and  122  and adjacent portions of railway car underframe  200  and between floor assembly  80  and adjacent portions of railway car underframe  200 . Isolator  302  disposed between adjacent portions of support posts  156  and respective side sill assembly  250  and isolator  304  disposed between floor assembly  80  and side sill assembly  250  are representative examples. Isolators  302  and  304  may be formed from various types of materials such as fiber reinforced plastic, PVC type material or any other satisfactory insulating material with both required strength and heat transfer characteristics to provide desired UA factor for box structure  30 .  
         [0092]     For some applications, a corner joint or corner connection such as shown in  FIG. 11  may be formed between the ends of each sidewall assembly and adjacent portions of an associated endwall assembly. Corner joint or corner connection  220  as shown in  FIG. 11  may include a respective corner post  222  formed from a metal plate. Various metal alloys such as aluminum and/or steel may be used to form corner post  220 . For some applications, corner post  222  may have a generally open, J-shaped or L-shaped cross section defined in part by extended leg  224 . Isolator  226  may be disposed on the exterior of corner post  222  between fiber reinforced plastic layer  130  of an associated endwall assembly  120  or  122 . Isolators  227  may also be disposed on the exterior of each corner post  222  between adjacent portions of fiber reinforced plastic layer  170 . For some applications, fiber reinforced layer  170  may overlap portions of fiber reinforced layer  130 . One or more support plates  228  may be attached with support post  222  to accommodate attachment of ladder  206 . For embodiments such as shown in  FIG. 11 , one or more isolators  229  may be disposed between support plate  228  and adjacent portions of corner post  222 .  
         [0093]     For some applications, a metal angle (not expressly shown) may be attached with the lower portion or bottom portion of each endwall assembly  120  and  122  opposite from respective top chord  134 . The angle may also be described as an end sill used to attach respective endwall assembly  120  and  122  with adjacent portions of railway car underframe  200 . One leg of the angle (not expressly shown) may be welded with adjacent portions of metal sheets  124  proximate the lower portion or bottom of each sidewall assembly  120  and  122 . The other leg of the end sill may be attached with adjacent portions of side sill assemblies  150  and  152  and end sill  214  and associated ends of longitudinal stringers  230 . As shown in  FIG. 3 , channel  218  may be disposed between floor assembly  80  and adjacent portions of center sill  214 . Each end sill may also be disposed on channel  218  at the respective ends of railway car underframe  200 .  
         [0094]     Portions of the interior of insulated boxcar  20  may be insulated using various microsphere infused coatings such as a ceramic/epoxy coating. This material accommodates design considerations required of an insulated boxcar, due to its performance characteristics. By mixing microspheres into an epoxy paint system, the resulting material is lightweight, has a relatively high compressive strength, strong corrosion resistance and the durability necessary in severe (e.g., hot and/or cold) loading and/or unloading environments. Such characteristics make is possible to construct an insulated boxcar without a traditional wood interior.  
         [0095]     A layer of insulating coating  300  may be placed on interior portions of floor assembly  40 , sidewall assemblies  150  and  152 , endwall assemblies  120  and  122  and roof assembly  80 . See  FIG. 3 . For some applications, insulating coating  300  may have a thickness of approximately one-fourth of an inch or greater on interior surface  42  of floor assembly  80 . See  FIG. 7 . For some applications, insulating coating  300  may have a ceramic microsphere density of approximately 40% to 60%. The thickness of the coating  300  on interior surfaces  162  of sidewall assemblies  150  and  152  and interior surfaces  124  of each endwall assembly  120  and  122  may be approximately 0.020 inches. For some applications, fiber reinforced plastic strands may also be placed within insulating coating  300 . Such coatings are available from International Coatings.  
         [0096]     Various coatings having microspheres infused therein may be used to coat interior surfaces of box structure  30 . For some applications, an epoxy based coating having ceramic microspheres mixed throughout are applied at various locations on the interior of box structure  30 . Many different types of microspheres are available. The present invention is not limited to ceramic microspheres. The ceramic microspheres may have a size approximately equal to that of a single grain of flour (slightly thicker than an human hair). The wall thickness of each microsphere may be approximately one-tenth of the sphere diameter. Microspheres may be provided that have strengths within a magnitude of 6,500 to 60,000 psi, a softening point of approximately 1,800 degrees centigrade, resistance to chemical degradation, and relatively low thermal conductivity of approximately 0.1 W/m/Celsius degree. Such ceramic microspheres may be non-toxic and non-combustible.  
         [0097]     The microspheres generally have a hollow center. Most or all gasses may be removed from the center in an effort to create or mimic a vacuum. According to the laws of physics, nothing can move by conduction through a vacuum, since there is little to no matter present. Accordingly, microspheres that include a vacuum or approximate a vacuum at their centers are excellent insulators. Microspheres may be combined with a base material to form a coating with improved thermal resistance. For example, ceramic microsphere may be combined with a latex material to form a ceramic/latex coating or combined with an epoxy to form a ceramic/epoxy coating.  
         [0098]     When applied to interior surfaces of box structure  30 , ceramic microspheres may shrink down tight as water and other additives evaporate, creating a tightly packed array of cells (e.g., microspheres). This ceramic layer may provide a thermal barrier, improve fire resistance, protection from UV rays, repulsion of insects, and/or protection from destructive forces of weather. The ceramic cells may also increase longevity of the coating, which provides for less repair and/or maintenance of the insulated boxcar. Coatings and materials containing ceramic microspheres have excellent insulating capability. Such materials may be applied at strategic places in box structures  30  to help insulated boxcar  20  satisfy AAR heat transfer ratings while using a relatively small amount of space (e.g., thickness).  
         [0099]     One example of a universal boxcar formed in accordance with teachings of the present invention may have the following features: 
        286,000 lb. Gross Rail Load;     Standard car equipped with two 8′-0″ wide by 12′-4″ high insulated plug doors;     optional 15″ end-of-car cushioning unit;     Meets AAR Plate “F” Clearance Diagram;     Optional wireless monitoring system;     Ceramic/epoxy coating on interior surfaces;     Conventional urethane foam insulation;     Durable, wood free interior materials; and        
 
         [0108]     Lightweight nonmetallic exterior surfaces.  
                                                       Length Inside   60′-9″           Length Over Coupler Pulling Faces   69′-¾″           Length over Strikers   64′-8¾″           Length Between Truck Centers   46′-3″           Truck Wheel Base    5′-10″           Width, Extreme   10′-6⅝″           Width, Inside    9′-6″           Height, Extreme   16″-11⅞″           Height Inside at Center Line of Car   12′-10¾″           Estimated Lightweight    89,000 lbs.           Estimated Load Limit -    97,000 lbs.           Based on 286,000 lbs. Gross Rail Load           Gross Rail Load   286,000 lbs.           Cubic Capacity (Between bulkheads)    7,442 cubic feet           Cubic Capacity    7,442 cubic feet           (Level with height of sides)                      
 
         [0109]     Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alternations can be made herein without departing from the spirit and scope of the invention as defined by the following claims.