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CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit to U.S. Provisional Application No. 60/900,545 filed Feb. 9, 2007. 
     
    
     STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    This invention relates to portable restrooms, and in particular to portable restrooms providing increased interior space. 
         [0005]    2. Discussion of the Prior Art 
         [0006]    Portable restrooms, sometimes referred to as outhouses, are commonly rented and used for special events, such as parties, festivals or concerts, as well as at job sites or other locations where people are gathered temporarily. It is common to form portable restrooms from plastic resin. 
         [0007]    Common processes used to produce the walls and waste tanks of such portable restrooms include rotational molding, blow molding, thermoforming, and injection molding, as known to those skilled in the art of plastics. To reduce the need for framing or separate structural members for the cabin portion of the portable restroom, the plastic wall panels are molded to include angled surfaces or other integral structural members. Support for the cabin is provided by a base designed to support the weight of the cabin and keep it elevated from the ground. 
         [0008]    There has been a trend in the portable restroom industry to increase the interior space. This is driven in part by the needs of the users and the desire and/or requirement for additional items, like sinks and baby changing platforms, to be installed inside the portable restroom. 
         [0009]    In the industry, portable restrooms are generally classified in one of three standard categories, based primarily on the size of the unit. These are: (1) “utility” sized portable restrooms, having a roughly 41 square inch cabin footprint on a roughly 43 inch by 48 inch base; (2) a larger “handicap” accessible unit, for accommodating a wheelchair, which is roughly a 60 square inch or octagonal footprint; and (3) an even larger “ADA compliant” unit, which also accommodates a wheelchair but is built to comply to U.S. government regulations requiring a 60″ diameter open space on the floor to facilitate turning the wheelchair. 
         [0010]    Many rental operators request a portable restroom larger than the utility size but smaller than a handicapped or ADA compliant unit. The difficulty designing such a unit has heretofore been the size and configuration of the standardized base of a utility sized unit. Simply putting a larger unit on a smaller base will not work because of the transport equipment that utility units are moved on and because the base should be larger than the cabin, not smaller, to minimize tipping. Rental operators may be forced to use the two larger units to fulfill the need for additional space, even though the full extend of the space is not needed, for example to accommodate addition features or wheelchairs. The disadvantage of doing this is the much higher cost of such units and the difficulty and cost of transporting the larger and heavier units. 
       BRIEF SUMMARY OF THE INVENTION 
       [0011]    The present invention provides a portable restroom that has an expanded interior while maintaining a footprint with a standard depth dimension facilitating transport of the structure with conventional equipment. The depth dimension corresponds to that of conventional “utility” sized portable restrooms, and increased interior space is achieved by providing a width dimension approximately 1.5 times the depth dimension. Its base has two or more runners, at least two of which are spaced at another industry standard dimension for transport equipment used to haul utility sized structures. 
         [0012]    Specifically, the invention provides a portable plastic resin restroom having a cabin defining an enclosed interior, a tank disposed within the cabin interior for holding waste material, and a base supporting the tank and the cabin. The base has a depth dimension corresponding to a standardized dimension and a width dimension corresponding to about 1.5 times the standardized dimension. 
         [0013]    The base can be an assembly of a frame, runners and a floorboard. The base has at least two runners spaced apart along the width dimension to support the rest of the structure off of the ground. At least two of the runners are spaced at a second standardized dimension corresponding to the spacing of support rails in trailers and other transport equipment used in the industry to transport the structures. In some cases, three, four or more runners are used to support the structure. If there are three runners, then the third runner can be spaced from either of the other two, which are spaced at the standard dimension, by about ⅓ of the width dimension. In this way, if the structure is supported by only the two standard-spaced runners, then the center of the structure would fall between the supported runners and only ⅓ of the structure would be unsupported. If there are four runners, then there can be two pairs of standard spaced runners, with a runner of one pair being interposed between the other pair of runners. This arrangement allows the structure to be supported during transport by either set of standard spaced runners, thereby allowing flexibility in loading the structure on a transport vehicle. The pairs of runners can also be spaced from each other by about ⅓ of the width dimension to limit excessive overhang, as discussed above. 
         [0014]    The frame can define a rectilinear structural framework including structural members outlining the footprint of the cabin as well as cross-members extending therebetween. The frame members can be structural channel members. The frame supports the floorboard and tank from underneath, and the lower edges of the cabin walls are mounted to the frame members using any suitable connection technique, screws, bolts, rivets, etc. The runners can have integral mounting sections fitting within the associated channel members. The mounting section can have an elongated groove receiving a lip of the associated channel member. 
         [0015]    The runners are generally arranged in parallel and extend in the front-to-back depth dimension of the structure. It is desirable for the runners to extend beyond the walls of the cabin, or at least between the front and back frame members, to provide better stability tip prevention. However, to interfere with foot traffic into and out of the structure, if a runner is located near, such as directly below, the doorway access opening to the cabin, that runner or runners would extend forward a lesser distance that the others, and could be limited to not extend beyond the wall of the cabin defining the access opening. 
         [0016]    The foregoing and other features of the invention will appear from the following description. In this description reference is made to the accompanying drawings which form a part hereof and in which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a perspective view of a portable restroom of the present invention; 
           [0018]      FIG. 2  is a top plan view of the interior thereof; 
           [0019]      FIG. 3  shows three portable restrooms of the present invention loaded onto a trailer; 
           [0020]      FIG. 4  is a schematic representation of the footprints of two portable restrooms of the present invention superimposed of that of three standard utility sized portable restrooms; 
           [0021]      FIG. 5  is a perspective view of a base assembly for the portable restroom of the present invention; 
           [0022]      FIG. 6  is an enlarged partial section view taken along line  6 - 6  of  FIG. 5  showing the connection of a runner to a frame of the base assembly; and 
           [0023]      FIG. 7  is a bottom view of the base assembly showing the spacing of the runners along with the width of the portable restroom of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0024]      FIGS. 1 and 2  of the drawings illustrates one preferred embodiment of a portable restroom  10  according to the present invention. The portable restroom  10  has as its primary components a cabin  12 , a waste tank  14  and a base assembly  16 . 
         [0025]    Generally, the cabin  12  has upright panels forming the vertical walls of the cabin  12  as well as the door frame  18  for a hinged door  20  and a roof  22 . The roof  22  is fastened to the upper end of the panels by rivets, bolts or other mechanical fasteners. The panels and the roof  22  define a covered interior space, accessible through the doorway, in which the tank  14  is disposed, along with any other suitable features, such as a paper dispenser, sink, changing table, mirror and the like. The panels can be formed and constructed to a rigid structure, or it can be hinged at the corners or even separated so that the structure can be collapsed and stacked or nested for shipment. The panel and roof  22  are formed of a plastic resin using any suitable forming technique. U.S. Pat. No. 6,823,639 to Hampel discloses one portable restroom in which the plastic resin panels are formed using a twin-sheet thermoforming technique and are made collapsible by using removable, extruded corner connectors. The disclosure of the this patent is hereby incorporated in its entirety as though it is fully set forth herein. The twin-sheet thermoforming technique has the advantage of being cost effective and allowing different features to be formed in opposite sides of the panels. 
         [0026]    The tank  14  is also formed of plastic resin. Any suitable tank construction and molding technique may be used. Co-pending and co-filed U.S. Provisional Application No. 60/888,594 filed on Feb. 7, 2007, and U.S. Provisional Application No. 60/900,500 filed on Feb. 9, 2007, entitled “Multi-Piece Tank for Portable Restroom” to Hampel discloses in detail the construction, formation, and functional aspects of one such tank, depicted in  FIG. 2 , and is hereby incorporated by reference in its entirety as though fully set forth herein. 
         [0027]    The cabin  12  and the tank  14  are supported by the base assembly  14 . As depicted in FIG.  5 ., the base assembly  14  includes a floorboard  30 , which along with the tank  14 , rests on a frame  32  to which runners  34  are mounted. Two long frame members are arranged in parallel and connected to the ends of two parallel short frame members to define generally rectangular footprint of the portable restroom  10 . Two cross members (not shown) beneath the floorboard  30  extend in parallel to the short frame members and connect to the two long frame members at intermediate locations thereof. In this way, the frame  32  forms a rigid structure to support the weight of the cabin  12 , the tank  14  and a user. The frame members can be structural channel members having a C configuration, which for the four outer frame members is oriented to opening inwardly. The channel configuration provides for strength with relatively low weight and thinner walls allowing the floorboard  30 , tank  14  and panels of the cabin  12  to be affixed to securely to the frame  32  using suitable mechanical fasteners. 
         [0028]    The channel configuration of the frame members also facilitates attachment of the runners  34 . Specifically, each of the runners  34  has an elongated foot that spans the depth of the cabin  12 , and except for one, extends beyond the front and rear of the cabin  12  to increase stability and reduce tipping. The one shorter runner does not extend in front of the cabin  12 , since it is beneath the door way and it could otherwise interfere with foot traffic into and out of the door way, and instead ends at the front panel or front frame member. In any event, each of the runners  34  has formed integrally therewith an elongated mounting section  36  at an upper side that fits into the open channel of the frame members, as shown in  FIG. 6 . The mounting sections  36  also form thin grooves  38 , which receive the short lips of the frame members. To further the connection, mechanical fasteners  40  can be used. 
         [0029]    The portable restroom  10  of the present invention has two significant advantages over other oversized portable restrooms, in other words portable restrooms larger than conventional utility size portable restrooms, and that is that while having half again as much interior space, both in terms of floor space and volume, its depth and runner spacing is standardized. 
         [0030]    Specifically, these two standardized dimensions pertain to two generally accepted dimension or dimension ranges corresponding to the construction and transport of what are commonly referred to in the industry as “utility” sized portable restrooms. Conventional utility portable restrooms have a cabin footprint of approximately 41 inches square. The bases for these cabins are approximately 43 inches wide by 48 inches deep, the depth dimension including the extended length of the runners. Conventional utility portable restrooms typically have exactly two runners spaced apart approximately 40 inches. 
         [0031]    Accordingly, for purposes of the invention disclosed herein and with reference to  FIG. 7 , the first standardized dimension related to the depth of the structure D is defined herein to mean the range of depth dimensions of standard utility sized portable restrooms. This standardized dimension most preferably pertains to the depth of the cabin footprint without the runners, however, it could also include the runners. The width of the structure W is then defined herein to mean a range of dimensions corresponding to about 1.5 times the depth dimension D. It is important to note that the width dimension W does not need to be 1.5×D in a strict mathematical sense, such that it can equal a dimension equal to about 1.5 times any depth dimension with the range of depth dimensions of any standard utility portable restroom, not necessary the actual depth dimension of the structure. For example, a range of depth dimensions for standard utility portable restrooms can be 40 to 43 inches. If a particular structure of the present invention measures 41 inches deep from front to back (D), its width (W) need not be 61.5 inches (41×1.5), but can be anywhere from about 60 inches (40×1.5) to about 64.5 inches (43×1.5). 
         [0032]    With reference to  FIG. 7 , the second standardized dimension relevant to the invention disclosed herein pertains to the spacing of the runners. This dimension corresponds to the dimension or range of dimensions between the support rails  50  on trailers  52  or other vehicles used in the industry to transport portable restrooms, as shown  FIG. 3 . Some such equipment has fixed rails, while others have adjustable spacing. Accordingly, this standard runner spacing dimension S is defined to mean the dimension or range of dimensions of spacing of the runners and corresponds to the spacing of the rails for supporting the structure, especially such rails on transport equipment. For example, about 40 inches can be one industry standard spacing dimension falling within a standard range of about 38-42 inches. It should be noted that that the actual spacing dimension S could correspond to the space between inward facing surfaces of a pair of runners, outward opposite surfaces of a pair of runners or at some intermediate point or axis of the runners such as the centerlines, as depicted in  FIG. 7 . This figure shows centerline-to-centerline spacing for simplicity. However, it may be best to consider the spacing dimension S as corresponding to the distance between the outer surfaces of a pair of runners because this dimension could more readily correspond to the distance between inside surfaces of the upright wall  54  of the rails  50 . 
         [0033]    It should further be noted that the term “about” is used herein as a term of approximation for a stated dimension or multiplier, allowing for a range of some fraction of the stated unit, but not to exceed an integer value thereof of. Thus, “about 42 inches” includes all dimensions between 41 and 43 inches, but not 41 inches or 43 inches. 
         [0034]    The portable restroom of the present invention can thus provide additional interior space to better accommodate the needs of larger or less able individuals and/or increase the number of fixtures inside. This can be done without significantly impacting their ability to be transported cost effectively. As shown in  FIGS. 3 and 4 , two of the portable restrooms  10  can fit in essentially the same space as three utility sized units (represented by dashed lines in  FIG. 4 ). And, as shown in  FIG. 3 , the spacing of the runners  34  according to the present invention allows the portable restrooms  10  to be loaded on the trailer  52  without requiring the location of the rails  50  to be changed or for additional rails to be added. Moreover, the spacing of the runners  34  provide for the center of the restrooms to be between the runners supported by the rails, whether it the support rails be the first an third (from left to right) or the second and fourth as depicted in the two front facing portable restrooms  10  shown in  FIG. 3 . With this runner spacing, no more than about  1 / 3  of the portable restroom  10  will “hang” off to one side of the rails unsupported. The portable restrooms  10  will thus be well-balanced when loaded on the trailer for transport. 
         [0035]    It should be appreciated that merely a preferred embodiment of the invention has been described above. However, many modifications and variations to the preferred embodiment will be apparent to those skilled in the art, which will be within the spirit and scope of the invention. Therefore, the invention should not be limited to the described embodiment. To ascertain the full scope of the invention, the following claims should be referenced.

Summary:
A portable plastic resin restroom has an expanded interior space while maintaining a footprint with a standard depth dimension facilitating transport of the structure with conventional equipment. The depth dimension corresponds to that of conventional “utility” sized portable restrooms, and increased interior space is achieved by providing a width dimension half again as big. Its base has two or more runners, at least two of which are spaced at another industry standard dimension for transport equipment used to haul utility sized structures.