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BACKGROUND 
     The present invention relates to model railroading, and particularly to improving the realistic appearance of model railroad track, and more particularly to track having a center rail. 
     Realism in the appearance of trains and track, and the buildings, accessories, and other elements of attendant layout scenery, is a quality many model railroading hobbyists continually strive to achieve. One area of continuing frustration for these enthusiasts concerns the presence in certain types of model railroad track of its electrified rail which is centrally located between the two parallel wheel-bearing rails. Typically, this center rail is electrified by alternating current (AC) to provide electrical power to the train locomotive, which is typically powered by an AC or rectified direct current (DC) electric motor grounded through its wheels to the wheel-bearing rails of the track, which are also grounded. A center rail is generally not included in real-world track for nonelectric trains, and therefore provides what many consider an undesirable characteristic of certain types of model railroad track that detracts from its realism. It has long been desirable, therefore, to mask or camouflage the electrified center rail, while preserving its functional purpose of powering the locomotive. 
     One type of model railroading track utilizing an electrified center rail is O-gauge track, which has long been widely used. Certain example sections of O-gauge track still commonly used in model railroading layouts are shown in  FIGS. 1-3 , although it is to be understood that the present disclosure does not relate solely to examples depicted herein or to O-gauge track, but to any type of model railroad track whose appearance is beneficially altered by application of the present invention. Extant railroad track which includes a center rail is generally described as follows, with reference to  FIGS. 1-4 . 
     Herein, outward and inward generally refer to directions away from and towards the center rail, respectively. Extant track  20  include a pair of elongate wheel-bearing rails  22  each having inwardly facing lateral side  24 , an opposing, outwardly facing lateral side  26 , and a top surface  28  along which the train wheels roll. The top surface  28  may be defined on head  30  of the respective rail  22 . Opposite the head  30 , each rail  22  may be provided with base  32  on which the rail  22  appears to rest. Rail  22  may define a web  34  that extends vertically between head  30  and base  32 , providing rail  22  with a generally I-shaped cross-sectional shape. Typically, rail inward and outward lateral sides  24 ,  26  are defined by web  34  and portions of head  30 . In some track embodiments, base  32  is planar and substantially horizontal, and simulates having a bottom surface resting upon a plurality of simulated tie plates  36 . In such embodiments the rail base  32  and tie plates  36  may appear to be affixed by track spikes  38  to top surface  40  of one of a plurality of crossties  42 . 
     Crossties  42 , which may, for example, be molded plastic or shaped wood, are elongate and in some track embodiments simulate in color and texture the appearance of the wooden crossties they are intended to replicate. In the depicted track embodiments, each crosstie  42  extends between opposing axially opposite ends  44 ,  46  which are planar, and have opposing, planar first and second side surfaces  48 ,  50  facing directions along which rails  22  extend. First side surface  48  and second side surface  50  of adjacent crossties  42  interface each other and are spaced along rails  22 . In the depicted track embodiments, opposite crosstie top surfaces  40  is planar bottom surface  52  which may or may not fully extend between crosstie first and second side surfaces  48 ,  50 , depending on the crosstie material or forming method. Each depicted crosstie  42  has central axis  54  that extends between and is normal to opposing axially opposite ends  44 ,  46 . In straight track sections  20 , central axes  54  are parallel; in curved track sections  20  central axes  54  converge in a radial direction toward the inside of the curve and diverge in the opposite radial direction, toward the outside of the curve. 
     Extant track sections  20  include a singular, elongate electrified rail  60  centrally disposed between the pair of wheel-bearing rails  22 . Because center rail  60  is electrified, it must be electrically isolated from wheel-bearing rails  22 , and may be electrically insulated from crossties  42  (and thus from rails  22 ), or may be electrically isolated from rails  22  by virtue of crossties  42  themselves being electrically insulative. For example, crossties  42  may be formed of a dielectric material such as plastic or wood as described above. 
     Center rail  60  has opposing lateral sides  62  that interface inward lateral sides  24  of rails  22 . Center rail  60  has top surface  64  that may or may not, depending on manufacturer, be defined on a head  66  (similar to head  30 ) of the respective rail  60 . When viewed in cross-sections taken perpendicular to the longitudinal axes of rails  22  and  60 , center rail top surface  64  and wheel-bearing rail top surfaces  28  define a generally horizontal plane. Typically, top surfaces  28  and  64  are located at a common height above horizontal top planar surface  40  of crossties  42  in most extant track  20  embodiments. In certain extant track embodiments, center rail  60  may also be provided with a base  68  (similar to base  32 ), and lateral sides  62  that are defined by a web  70  (similar to web  34 ) extending vertically between head  66  and base  68 , to define a generally I-shaped cross-sectional shape. In certain embodiments, base  68  is substantially horizontal, and simulates having a bottom surface resting upon a plurality of simulated tie plates  72  (similar to tie plates  36 ). Alternatively, at each crosstie  42  base  68  may be hidden beneath crosstie top surface  40 . Typically, surface  40  is planar and horizontal, a configuration that accentuates the presence of the upstanding center rail  60 , as discussed further below. 
       FIG. 1  shows a straight section of extant O-gauge track  20   a  of a brand commercialized by Atlas Model Railroad Co., Inc. that has wheel-bearing rails  22   a , molded, brown plastic crossties  42   a  having a hollowed bottom surface  52 , and center rail  60   a . In track section  20   a , rails  22   a  and  60   a  each have head  30 ,  66  and base  32 ,  68  between which extends web  34 ,  70 . The cross-sections of rails  22   a  and  60   a  are solid, and the size of and/or spacing between crossties  42   a  are unique to that particular brand and size (e.g., O-gauge) of track. 
       FIG. 2  shows a straight section of extant O-gauge track  20   b  of a brand commercialized by M.T.H. Electric Trains that has wheel-bearing rails  22   b , molded, brown plastic crossties  42   b  having a hollowed bottom surface  52 , and center rail  60   b . In track section  20   b , rails  22   b  each have a solid cross-section, and head  30  and base  32  between which extends web  34 . The cross-section of rail  60   b  is also solid, but has uniformly rectangular vertical and horizontal portions; the vertical portion, which defines opposing lateral sides  62 , is bereft of a head portion, and perpendicularly intersects the upper surface of the horizontal rail portion which defines base  68 , thereby defining an inverted T shape. Each crosstie  42   b  is molded about base  68 , thereby defining in each crosstie a horizontal slot  74  containing base  68 , and vertical slot  76  in crosstie top surface  40  from which the vertical portion of center rail  60   b . The size of and/or spacing between crossties  42   b  are unique to that particular brand and size (e.g., O-gauge) of track. 
       FIG. 3  shows a straight section of extant O-gauge track  20   c  of a brand commercialized by GarGraves Trackage Corporation that has wheel-bearing rails  22   c , wooden, brown-stained crossties  42   c , and center rail  60   c . In track section  20   c , rails  22   c  and  60   c  each have head  30 ,  66  and base  32 ,  68  between which extends web  34 ,  70 . Rails  22   c  and  60   c  are formed of sheet metal and generally tubular, providing hollow cross-sections. Crossties  42   c  are provided with angled slots  56  into which flanges of rails  22   c  are fitted and angled slots  78  into which flanges of rail  60   c  are fitted, as shown. The size of and/or spacing between crossties  42   c  are unique to that particular brand and size (e.g., O-gauge) of track. 
     In track  20   a ,  20   b  and  20   c , center rail  60  is camouflaged and rendered somewhat less noticeable by its having a dark color, whereas rails  22  are relatively lighter in color. For example, center rail  60  may be black or a dark brown color similar to that of crossties  42 , whereas wheel-bearing rails  22  may be a color such as silver, brass, or gray providing greater contrast to the brown crossties. 
       FIG. 4  shows a straight section of prior O-gauge track  20   d  commercialized by Lionel Corporation as Super “O”™ model railroad track. In track  20   d , wheel-bearing rails  22   d  each have head  30  and base  32  between which extends web  34 . Rails  22   d  are formed of sheet metal and generally tubular, providing a hollow cross-section. Rail  60   d  has a substantially uniform rectangular cross-section and is darkly colored, as described above. Each crosstie  42   d  is molded, brown plastic and provided with a vertical slot  80  into which the bottom portion of center rail  60   d  is disposed. Unlike track  20   a ,  20   b  and  20   c , in track  20   d  the entire top surface  40  of crosstie  42   d  is not substantially horizontal between crosstie opposite axial ends  44 ,  46 . In track  20   d , each crosstie  42   d  has a planar portion of its top surface  40  that inclines from a location laterally inward of each rail  22   d  towards the interfacing side  62  of center rail  60   d . Thus, in track  20   d  laterally inward portions of crosstie  42   d , which are located adjacent center rail lateral sides  62 , cover and hide from view portions of center rail lateral sides  62 , rendering center rail  60   d  less noticeable than it would be were the entirety of crosstie surface  40  to define a horizonal plane, as it does in track  20   a ,  20   b  and  20   c.    
     Another popular but unshown example of extant track is an embodiment commercialized by Lionel Corporation and commonly known as Lionel tubular track, which is widely available in O-gauge. This type of track employs metal stampings as crossties. These crossties have horizontally planar top surfaces and open axial ends, are typically painted black, and are widely spaced along the length of each track section. In such track the wheel-bearing and center rails are bright silver and their bases are clamped via staking to the crossties, with the center rail insulated from each crosstie with a sheet of insulating material wrapped about the center rail base and a portion of the rail web. Comparatively, the appearance of Lionel tubular track is far less realistic than that of any of above-described track  20   a ,  20   b ,  20   c  and  20   d.    
     Prior track  20   a ,  20   b ,  20   c  and  20   d  represent the current state of the art with regard to camouflaging center rail  60 , with track  20   d , by virtue of its uniquely shaped crossties  42   d  which incline laterally inwardly towards the lateral sides  62  of center rail  60   d , generally considered to be the best existing approach towards rendering the center rail less noticeable and therefore imparting the most realistic appearance to the track. 
     There is, however, a substantial amount of extant track that is and will remain in use. Improving the aesthetics of model railroad layouts that utilize existing track having a center rail and crossties provided with top surfaces that substantially lie in horizontal planes between its wheel-bearing rails and the center rail, by at least partially covering or hiding the side of the center rail without compromising function, is desirable. 
     SUMMARY 
     The present disclosure provides an aesthetic insert adapted to be received between a wheel-bearing rail and the center rail of extant model railroad track. Herein, either of the two wheel-bearing rails of an extant track section may also be referred to as a first rail, or its center rail may also be referred to as a second rail. An installed insert superposes a crosstie portion(s) located between the first and second rails, and simulates the presence and/or appearance of a track crosstie portion(s). In its installed position, an insert according to the present disclosure at least partially covers or hides one lateral side of the (second or) center rail, thereby camouflaging the center rail and rendering it less noticeable. The insert may be a separately installable, individual element, or a plurality of interconnected individual elements installable as a group and interconnected by one or more connecting members. 
     The present disclosure provides an aesthetic insert for use with extant model railroad track having spaced, elongate and parallel first and second rails each having a top surface and mutually interfacing sides. The extant model railroad track also has a plurality of spaced crossties extending between and at least partially located beneath the attached first and second rails, each of the plurality of crossties having a top surface located between the first and second rails. The sides of the first and second rails have a substantially common height from the top surface of the crosstie to the respective top surfaces of the first and second rails. The insert has an installed position relative to the extant model railroad track between the first and second rails. The insert includes an insert element defined by an upper portion adapted to superpose at least a portion of the top surface of a crosstie. The upper portion has an upper surface adapted to simulate the presence and/or appearance of a surface of a crosstie. The upper portion defines an outer edge located proximate the side of the first rail at a first distance below the top surface of the first rail in the installed position. The upper portion defines an inner edge located proximate the side of the second rail at a second distance below the top surface of the second rail in the installed position, and the first distance is substantially greater than the second distance, whereby the side of the second rail is partially hidden from view by the insert in the installed position. 
     A further aspect of the present disclosure is that the outer and inner edges are substantially parallel. 
     A further aspect of the present disclosure is that, in the installed position, the second distance is substantially less than a third distance to the inner edge above the top surface of the crosstie superposed by the upper portion. 
     A further aspect of the present disclosure is that the upper portion upper surface is substantially planar. 
     A further aspect of the present disclosure is that the insert also includes spaced first and second side portions depending from the upper portion, and the side portions are adapted to at least partially enclose a space located between the upper portion and the top surface of the crosstie superposed by the upper portion in the installed position. 
     According to another aspect of the present disclosure, the first and second side portions and the upper portion are integrally-formed of molded dielectric material. 
     According to another aspect of the present disclosure, the first and second side portions are adapted to superpose portions of opposing surfaces of a crosstie in the installed position. 
     According to another aspect of the present disclosure, the first and second side portions are substantially planar. 
     According to another aspect of the present disclosure, the first and second side portions define a pair of opposing exterior side surfaces each adapted to simulate the appearance of a surface of a crosstie. 
     A further aspect of the present disclosure is that the insert includes an interconnected plurality of insert elements, each insert element having an upper portion adapted to superpose a different one of the plurality of crossties in the installed position. 
     According to another aspect of the present disclosure, the plurality of insert elements is interconnected proximate the side of the second rail in the installed position. 
     According to another aspect of the present disclosure, the insert includes a connecting member extending between two insert elements, with the connecting member disposed proximate the inner edges of the respective insert elements and extending along the side of the second rail in the installed position. 
     An additional aspect of the disclosure is that the connection member is flexible and the two insert elements are adapted to have different orientations relative to each other in the installed position. 
     According to another aspect of the present disclosure, each upper portion is elongate and is bisected by a plane extending between the respective outer and inner edges, with each insert element substantially symmetrical about the respective plane thereof. 
     An additional aspect of the disclosure is that the insert is adapted to be received between the first and second rails of a section of extant model railroad track and, relative to a received insert in the installed position, the planes of an adjacent pair of respective insert elements are substantially parallel along a straight section of the extant model railroad track, and/or converge in a direction from the respective outer edges to the respective inner edges along a curved section of the extant model railroad track whose first rail defines an outside curve, and/or diverge in a direction from the respective outer edges to the respective inner edges along a curved section of the extant model railroad track whose first rail defines an inside curve. 
     A further aspect of the present disclosure is that the insert is adapted to retentively engage at least one surface of a superposed crosstie in the installed position. 
     A further aspect of the present disclosure is that the insert is adapted to retentively engage opposing surfaces of a superposed crosstie in the installed position. 
     A further aspect of the present disclosure is that the insert is adapted to retentively engage a bottom surface of a superposed crosstie in the installed position. 
     According to another aspect of the present disclosure, the insert element includes spaced first and second side portions depending from the upper portion, with the first and second side portions adapted to superpose portions of opposing surfaces of a crosstie in the installed position. The first and second side portions are provided with lips adapted to superpose a bottom surface of a superposed crosstie in the installed position. 
     A further aspect of the present disclosure is that the insert is adapted to retentively engage at least one of the first and second rails in the installed position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned aspects and other characteristics and advantages of an apparatus and/or method according to the present disclosure will become more apparent and will be better understood by reference to the following description of exemplary embodiments taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a section of extant O-gauge model railroad track commercialized by Atlas Model Railroad Co., Inc.; 
         FIG. 2  is a perspective view of a section of extant O-gauge model railroad track commercialized by M.T.H. Electric Trains; 
         FIG. 3  is a perspective view of a section of extant O-gauge model railroad track commercialized by GarGraves Trackage Corporation; 
         FIG. 4  is a perspective view of a section of prior O-gauge Super “O”™ model railroad track commercialized by Lionel Corporation; 
         FIG. 5  is an exploded perspective view of a section of extant model railroad track and a plurality of first embodiment inserts according to the present disclosure; 
         FIG. 6A  is a perspective view of a first embodiment insert according to the present disclosure; 
         FIG. 6B  is a top view of the insert shown in  FIG. 6A ; 
         FIG. 6C  is a side view of the insert shown in  FIG. 6A ; 
         FIG. 6D  is an inner end view of the insert shown in  FIG. 6A ; 
         FIG. 7A  is a fragmented side view of a first embodiment insert shown in the installed position relative to a section of extant model railroad track; 
         FIG. 7B  is a fragmented opposite side view of a variation of a first embodiment insert shown in the installed position relative to a section of extant model railroad track; 
         FIG. 7C  is a view similar to  FIG. 7B , showing distances between portions of the insert and the track; 
         FIG. 8  is an exploded perspective view of a section of extant model railroad track and a plurality of second embodiment inserts according to the present disclosure; 
         FIG. 9A  is a perspective view of a second embodiment insert according to the present disclosure; 
         FIG. 9B  is a top view of the insert shown in  FIG. 9A ; 
         FIG. 9C  is an inner end view of the insert shown in  FIG. 9A ; 
         FIG. 9D  is a side view of the insert shown in  FIG. 9A ; 
         FIG. 10A  is a fragmented side view of a second embodiment insert shown in the installed position relative to a section of extant model railroad track; 
         FIG. 10B  is a fragmented opposite side view of a variation of a first embodiment insert shown in the installed position relative to a section of extant model railroad track; 
         FIG. 10C  is a view similar to  FIG. 10B , showing distances between portions of the insert and the track; and 
         FIG. 11  is a plan view of a curved section of extant railroad track and a pair of second embodiment inserts in their installed positions on laterally opposite sides of the central rail, the inserts shown shaded for clarity. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent an embodiment of the disclosed apparatus, system and/or method, the drawings are not necessarily to scale or to the same scale and certain features may be exaggerated in order to better illustrate and explain the present disclosure. Moreover, in accompanying drawings that show sectional views, cross-hatching of various sectional elements may have been omitted for clarity. It is to be understood that any omission of cross-hatching is for the purpose of clarity in illustration only. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The embodiments of the present disclosure are not intended to be exhaustive or to limit the invention to the precise forms or steps disclosed in the following detailed description, but have been chosen and are herein described so that others skilled in the art may appreciate and understand principles and practices according to the present disclosure. It is, therefore, to be understood that the invention herein described is not limited in its application to the details of construction and the arrangement of components or steps set forth in the following description or illustrated in the drawings, and is capable of having other embodiments and of being practiced or of being carried out in various ways. 
       FIG. 5  shows a plurality of aesthetic insert  100  according to a first embodiment in which each insert  100  is an individual, unitary insert element separate from other insert elements. Each insert element  100  is individually received between a wheel bearing rail  22  and the center rail  60  of an extant railroad track section  20 . Regardless of the embodiment being discussed, the accompanying drawings show insert installation relative to above-mentioned track section  20   c , but this particular type of track is to be understood as being merely one example of several types (e.g., track sections  20   a ,  20   b ,  20   c ) having a center rail  60  which is partially hidden or camouflaged by the installed aesthetic insert to make it less noticeable impart a higher degree of realism to the appearance of the track. 
     Referring to  FIGS. 6A-6D , each first embodiment insert  100  has an upper portion or upper panel  102  defining generally planar upper surface or exterior surface  104  that superposes top surface  40  of crosstie  42  between the interfacing lateral sides  24 ,  62  of a wheel-bearing rail  22  and center rail  60 . Upper portion  102  of each insert element  100  has outer edge  106  and inner edge  108  which, in the installed position of insert  100 , are disposed adjacent to inwardly-facing lateral side  24  of wheel-bearing rail  22  and superposing outwardly-facing lateral side  62  of center rail  60 . Planar upper surface  104  is substantially rectangular and provided with bifurcating central axis  158  extending through outer and inner edges  106 ,  108 , as best seen in  FIG. 6B . Axis  158  defines and extends along imaginary plane  160  about which insert element  100  is substantially symmetrical, as best seen in  FIG. 6D . In the installed position of insert  100 , central axis  54  of the crosstie  42  partially covered thereby becomes positioned coextensively with plane  160 . 
     Each insert  100  has first side portion or first side panel  110  and second side portion or second panel  112 . First and second side portions  110 ,  112  are substantially parallel and, in the installed position, each superposes first side surface  48  or second side surface  50  of the superposed crosstie  42 , depending on which lateral side of center rail  60  insert  100  is installed. 
     Insert element first side panel  110  has outer edge  114  and insert element second side panel  112  has outer edge  116  that is substantially parallel with outer edge  114 . Insert element first side panel  110  has inner edge  118  and insert element second side panel  112  has inner edge  120  that is substantially parallel with inner edge  118 . Insert element first side panel  110  has top edge  122  that is contiguous with first side edge  124  of insert upper portion  102 . Insert element second side panel  112  has top edge  126  that is contiguous with second side edge  128  of insert upper portion  102 . The junctures between edges  122  and  124 , and the juncture between edges  126  and  128  are substantially linear and parallel. 
     Insert element first side panel  110  has bottom edge  130 , and insert element second side panel  112  has bottom edge  132 . Bottom edges  130  and  132  are substantially parallel. Referring to  FIGS. 6C, 6D and 7A , bottom edges  130  and  132  may be provided with lips  134  and  136 , respectively, which extend towards each other and are adapted to superpose portions of crosstie bottom surface  52  in the installed position. Lips  134 ,  136  thus define a retention feature by which insert  100  is retained in its installed position through the abutment engagement between lips  134 ,  136  and crosstie bottom surface  52 . Alternatively, bottom edges  130 ,  132  may be located along their respective adjacent crosstie side surface  48 ,  50  in the installed position, as shown in  FIG. 7B , with insert  100  retained through frictional engagement between its side panels  110 ,  112  and the crosstie surfaces  48 ,  50  superposed thereby. In some embodiments, bottom edges  130 ,  132  may superposingly abut cross tie top surface  40  in the installed position. Insert  100  may also be bonded in place relative to its respective crosstie  42  with a suitable adhesive. 
     Insert element  100  may be molded of an elastically deformable plastic material, as by, for example, an injection molding process. Insert element upper portion  102  and first and second side portions  110 ,  112  are integrally formed. Insert elements  100  may be molded as a plurality of elements interconnected by runners of an injection molded part, and which are separated from each other subsequent to the molding process. The molded material may be of a color substantially matching that of the crossties  42  of a particular brand and size (e.g., O-gauge) of extant track  20 . Alternatively, inserts  100  may be painted or dyed to substantially match the crosstie color. First and second side panels  110 ,  112  respectively define exterior surfaces  138 ,  140 , and insert exterior surfaces  104 ,  138  and  140  may be provided with a texture  154  substantially matching the texture  156  of crosstie surfaces  40 ,  48  and  50 , as indicated in  FIG. 5 . Thus, not only the presence of a crosstie surface, but the appearance of a crosstie surface, may be simulated by insert  100 . 
     Lower or interior surface of insert element upper panel  102  defines lower or interior surface  142 , and insert element first and second side panels  110 ,  112  respectively define interior surfaces  144 ,  146 . Referring to  FIGS. 7A and 7B , in the installed position surfaces  142 ,  144  and  146  of insert  100 , and the portion of crosstie top surface  40  superposed by insert  100 , define enclosed, wedge-shaped space  148 . 
     Outer edges  106 ,  114  and  116 , and inner edges  108 ,  118  and  120 , of insert element  100  may be configured to respectively define outer retention feature  150  and inner retention feature  152  adapted to engage the respective, adjacent one of interfacing rail lateral sides  24  and  62  in the installed position, as shown in  FIGS. 7A and/or 7B . Retention features  150  and  152  may be variously configured to best engage and retain insert  100  to rails  22 ,  60  depending on the particular brand and size (e.g., O-gauge) of extant track  20  associated with a particular variant of the insert. Retention of insert  100  in its installed position may also be accomplished by use of a suitable adhesive, as mentioned above, or through engagement between surfaces of the superposed crosstie  42  and insert element side panels  110 ,  112  and/or lips  134 ,  136  that may be provided along their bottom edges  130 ,  132 . 
     Referring to  FIG. 7C , it can be seen that in the installed position, outer edge  106  of insert element  100 , located proximate inward lateral side  24  of wheel-bearing rail  22 , is located at distance D 1  below the generally horizontal plane defined by rail top surfaces  28  and  64 , and that inner edge  108  of insert element  100 , located proximate interfacing lateral side  62  of center rail  60 , is located at distance D 2  below that plane, with distance D 1  substantially greater than distance D 2 . Consequently, lateral side  62  of center rail  60  is partially hidden from view by insert element  100  in the installed position, with inner edge  108  of insert element  100  located at distance D 3  above planar top surface  40  of crosstie  42 . Distance D 3  is preferably substantially greater than distance D 2 , whereby a greater portion of center rail lateral side  62  is hidden than is visible within the width of insert element  100  between its opposing exterior surfaces  138  and  140 . Furthermore, distance D 1  is sufficiently below wheel-bearing rail top surface  28  so as not to interfere with the flanges of train wheels, which extend below wheel-bearing rail top surface  28  and travel along inward lateral side  24  of each rail  22 . Moreover, distance D 2  is sufficiently below center rail top surface  64  so as not to interfere with the electrical connection between the locomotive&#39;s electrical contact (not shown) that engages top surface  64  of powered center rail  60 , typically by sliding therealong as the train moves along track  20 . 
       FIG. 8  shows an insert including plurality of interconnected aesthetic insert elements  200  according to a second embodiment in which each insert element  200  has a configuration similar to an above-described insert element  100 . Each adjacent pair of insert elements  200  is interconnected by a connecting member  262 , whereby the plurality of insert elements  200  and their interconnecting connecting member(s)  262  define aesthetic insert  264  that is received between a wheel bearing rail  22  and the center rail  60  of an extant railroad track section  20 . Except where noted or clear from its context in view of the Figures, it is to be understood that the following description of an insert element  200  relates to each respective one of the interconnected plurality of insert elements  200  in insert  264 . 
     Referring to  FIGS. 9A-9D , each second embodiment insert element  200  has an upper portion or upper panel  202  defining generally planar upper surface or exterior surface  204  that superposes top surface  40  of crosstie  42  between the interfacing lateral sides  24 ,  62  of a wheel-bearing rail  22  and center rail  60 . Upper portion  202  of each insert element  200  has outer edge  206  and inner edge  208  which, in the installed position of the interconnected plurality of insert elements  200 , are disposed adjacent to inwardly-facing lateral side  24  of wheel-bearing rail  22  and superposing outwardly-facing lateral side  62  of center rail  60 . Each planar upper surface  204  is substantially rectangular and provided with bifurcating central axis  258  extending through outer and inner edges  206 ,  208 , as best seen in  FIG. 9B . Each axis  258  defines and extends along an imaginary plane  260  about which the respective insert element  200  is substantially symmetrical, as best seen in  FIG. 9C . In the installed position of the plurality of interconnected insert elements  200 , central axes  54  of the crossties  42  partially covered thereby become positioned coextensively with plane  260 . 
     Each insert element  200  has first side portion or first side panel  210  and second side portion or second panel  212 . First and second side portions  210 ,  212  are substantially parallel and, in the installed position, each superposes first side surface  48  or second side surface  50  of its respective superposed crosstie  42 , depending on which lateral side of center rail  60  the plurality of interconnected insert elements  200  is installed. 
     Each insert element first side panel  210  has outer edge  214  and insert element second side panel  212  has outer edge  216  that is substantially parallel with outer edge  214 . Insert element first side panel  210  has inner edge  218  and insert element second side panel  212  has inner edge  220  that is substantially parallel with inner edge  218 . As best shown in  FIGS. 9A and 9B , each connecting member  262  is elongate and ribbon-like, having opposing outer surface  235  and inner surface  237 . Connecting member  262  is integrally connected at its opposite ends to the to insert element side portions  210 ,  212 , with connecting member inner surface  237  coextensive with insert element side portion inner edges  218 ,  220 . Insert element first side panel  210  has top edge  222  that is contiguous with first side edge  224  of insert upper portion  202 . Insert element second side panel  212  has top edge  226  that is contiguous with second side edge  228  of insert upper portion  202 . The junctures between edges  222  and  224 , and the juncture between edges  226  and  228  are substantially linear and parallel. 
     Each insert element first side panel  210  has bottom edge  230 , and each insert element second side panel  212  has bottom edge  232 . Bottom edges  230  and  232  are substantially parallel. Referring to  FIGS. 9C, 9D, and 10A , bottom edges  130  and  132  may be provided with lips  234  and  236 , respectively, which extend towards each other and are adapted to superpose portions of crosstie bottom surface  52  in the installed position. Lips  234 ,  236  thus define a retention feature by which each insert element  200  is retained in its installed position through the abutment engagement between the lips and crosstie bottom surface  52 . Alternatively, bottom edges  230 ,  232  may be located along their respective adjacent crosstie side surface  48 ,  50  in the installed position, as shown in  FIG. 10B , with insert element  200  retained through frictional engagement between its side panels  210 ,  212  and the crosstie surfaces  48 ,  50  superposed thereby. In some embodiments, bottom edges  230 ,  232  may superposingly abut cross tie top surface  40  in the installed position. Insert element  200  may also be bonded in place relative to its respective crosstie  42  with a suitable adhesive. Further, inner surface  237  of connecting member(s)  262  may be similarly bonded to the respective center rail lateral side  62  abutted thereby. 
     The interconnected plurality of insert elements  200  and interconnecting member(s)  262  may be molded of an elastically deformable plastic material, as by, for example, an injection molding process. The insert upper portion  202  and first and second side portions  210 ,  212  of each insert element  200 , and the connecting member(s)  262  are integrally formed. Inserts  264  may be molded as a plurality of elements  200  and connecting members  262  interconnected by runners of an injection molded part, with each insert  264  separated from another subsequent to the molding process. The molded material may be of a color substantially matching that of the crossties  42  of a particular brand of extant track  20 . Alternatively, the interconnected plurality of insert elements  200  may be painted or dyed to substantially match the crosstie color. First and second side panels  210 ,  212  respectively define exterior surfaces  238 ,  240 , and insert exterior surfaces  204 ,  238  and  240  may be provided with a texture  254  substantially matching the texture  156  of crosstie surfaces  40 ,  48  and  50 , as indicated in  FIG. 8 . Thus, not only the presence of a crosstie surface, but the appearance of a crosstie surface, may be simulated by insert  264 . 
     Lower or interior surface of each insert element upper panel  202  defines lower or interior surface  242 , and insert element first and second side panels  210 ,  212  respectively define interior surfaces  244 ,  246 . Referring to  FIGS. 10A and 10B , in the installed position surfaces  242 ,  244  and  246  of each insert element  200 , and the portion of respective crosstie top surface  40  superposed by that insert element  200 , define enclosed, wedge-shaped space  248 . 
     Outer edges  206 ,  214  and  216 , and inner edges  208 ,  218  and  220 , of each insert element  200  may be configured to respectively define outer retention feature  250  and inner retention feature  252  adapted to engage the respective, adjacent one of interfacing rail lateral sides  24  and  62  in the installed position, as shown in  FIGS. 10A and/or 10B . Additionally, inner surface  237  of each connecting member  262  may be configured to define inner retention feature  252 . Retention features  250  and  252  may be variously configured to best engage and retain insert  264  to rails  22 ,  60  depending on the particular brand and size (e.g., O-gauge) of extant track  20  associated with a particular variant of the insert. Retention of insert  264  in its installed position may also be accomplished by use of a suitable adhesive, as mentioned above, or through engagement between surfaces of the superposed crosstie  42  and insert element side panels  210 ,  212  and/or lips  234 ,  236  that may be provided along their bottom edges  230 ,  232 . 
     Connecting member(s)  262  is flexible, and conforms to the curvature of interfacing center rail lateral side  62 . Referring to  FIG. 11 , which shows a curved extant railroad track section  20 , insert  264  may have an installed position in which it is received between center rail  60  and the wheel bearing rail  22 ,  270  disposed at the inside of the curve, indicated by radially-directed arrow  266 . Insert  264  may also have an installed position in which it is received between center rail  60  and the wheel bearing rail  22 ,  272  disposed at the outside of the curve, indicated by radially-directed arrow  268 . With insert  264  installed between center rail  60  and wheel-bearing rail  270 , above-mentioned planes  260  thereof converge in the direction of arrow  266 . With insert  264  installed between center rail  60  and wheel-bearing rail  272 , above-mentioned planes  260  thereof diverge in the direction of arrow  268 . 
     Referring to  FIG. 10C , it can be seen that in the installed position, outer edge  206  of insert element  200 , located proximate inward lateral side  24  of wheel-bearing rail  22 , is located at distance D 1  below the generally horizontal plane defined by rail top surfaces  28  and  64 , and that inner edge  208  of insert element  200 , located proximate interfacing lateral side  62  of center rail  60 , is located at distance D 2  below that plane, with distance D 1  substantially greater than distance D 2 . Consequently, lateral side  62  of center rail  60  is partially hidden from view by insert element  200  in the installed position, with inner edge  208  of insert element  200  located at distance D 3  above planar top surface  40  of crosstie  42 . Distance D 3  is preferably substantially greater than distance D 2 , whereby a greater portion of center rail lateral side  62  is hidden than is visible within the width of insert element  200  between its opposing exterior surfaces  238  and  240 . Furthermore, distance D 1  is sufficiently below wheel-bearing rail top surface  28  so as not to interfere with the flanges of train wheels, which extend below wheel-bearing rail top surface  28  and travel along inward lateral side  24  of each rail  22 . Moreover, distance D 2  is sufficiently below center rail top surface  64  so as not to interfere with the electrical connection between the locomotive&#39;s electrical contact (not shown) that engages top surface  64  of powered center rail  60 , typically by sliding therealong as the train moves along track  20 . 
     While exemplary embodiments have been disclosed hereinabove, the invention is not necessarily limited to the disclosed embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of the present disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this present disclosure pertains and which fall within the limits of the appended claims.

Summary:
An aesthetic insert adapted to be received between a wheel-bearing rail and the center rail of extant model railroad track, and in its installed position at least partially covers or hides the side of the center rail, camouflaging it and rendering it less noticeable. The installed insert superposes portions of and simulates the presence and/or appearance of a crosstie surface. The insert may be a separately installable, individual element, or a plurality of interconnected individual elements installable as a group and interconnected by one or more connecting members.