Patent Publication Number: US-2022212800-A1

Title: Lavatory systems within an internal cabin of a vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application relates to and claims priority benefits from U.S. Provisional Patent Application No. 63/133,308, entitled “Lavatory Systems Within an Internal Cabin of a Vehicle,” filed Jan. 2, 2021, which is hereby incorporated by reference in its entirety. 
     This application also relates to and claims priority benefits from U.S. Provisional Patent Application No. 63/133,309, entitled “Lavatory Systems Having Storage Compartments,” filed Jan. 2, 2021, which is hereby incorporated by reference in its entirety. 
     This application also relates to and claims priority benefits from U.S. Provisional Patent Application No. 63/133,310, entitled “Lavatory Systems Having Containment Compartments,” filed Jan. 2, 2021, which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     Embodiments of the present disclosure generally relate to lavatories within an internal cabin of a vehicle, such as a commercial aircraft. 
     BACKGROUND OF THE DISCLOSURE 
     Commercial aircraft are used to transport passengers between various locations. A typical commercial aircraft includes one or more lavatories within an internal cabin. 
     Space within a commercial aircraft is limited. Notably, a lavatory within a commercial aircraft is typically relatively small in order to reduce space of the lavatory and increase space for other areas, such as passenger seating. A larger lavatory would necessarily occupy more space within a commercial aircraft, and may prevent additional passenger seating within an internal cabin. Aircraft operators typically prefer to have additional passenger seating within an internal cabin, as the additional passenger seating leads to increased revenues. 
     A typical lavatory within an internal cabin of an aircraft typically occupies approximately 20%-30% more longitudinal area (that is, an area that extends along and/or parallel to a longitudinal axis) of the internal cabin than a seat assembly. In general, current lavatories generally displace six to twelve passenger seats. Certain internal cabins may be rearranged to ensure only six displaced passenger seats, but thereby cause cascading impacts to surrounding interior features, such as other monuments or areas within the internal cabin. Overall, including lavatories within an internal cabin of a commercial aircraft, while typically necessary, reduces space for other components, monuments, or the like within the internal cabin, such as revenue-generating seats. 
     Further, persons of reduced mobility (such as individuals having disabilities, injuries, or a reduced ability to move) may find the confined space of a lavatory within a commercial aircraft relatively difficult to maneuver therein. Such individuals may have difficulty moving within the lavatory, such as between an entrance and a toilet, and between a toilet and a sink. 
     Accordingly, certain manufacturers have designed larger lavatories that are specifically designed for persons of reduced mobility. However, in expanding the size of the lavatory, space for other components (such as passenger seating) within an internal cabin is necessarily reduced. 
     SUMMARY OF THE DISCLOSURE 
     A need exists for a lavatory system including multiple lavatory units that occupy less space than known lavatories within an internal cabin of a vehicle. A need exists for a lavatory system including multiple lavatory units that occupy less space than an equivalent number of individual lavatories. Further, a need exists for a lavatory system that is readily and easily accessible by persons of limited mobility. Also, a need exists for a multi-unit lavatory system that does not reduce space for additional seating within an internal cabin of a vehicle. 
     With those needs in mind, certain embodiments of the present disclosure provide a lavatory system within an internal cabin of a vehicle. The lavatory system includes an enclosure defining an interior chamber, a first lavatory unit within the interior chamber, and a second lavatory within the interior chamber. The first lavatory unit is adjacent to the second lavatory unit. In at least one embodiment, the enclosure is a single monument within the internal cabin. As an example, the first lavatory unit and the second lavatory unit are side-to-side across a portion of the internal cabin. As an example, the first lavatory unit is inboard from the second lavatory unit within the internal cabin, and the second lavatory unit is outboard from the first lavatory unit within the internal cabin. 
     In at least one embodiment, the enclosure includes a first end wall. An inboard wall is connected to the first end wall. The inboard wall faces an aisle of the internal cabin. A second end wall is connected to the inboard wall. The second end wall is opposite from the first end wall. The second end wall faces an egress path of the internal cabin. An outboard wall is connected to the first end wall and the second end wall. 
     In at least one embodiment, the second end wall includes a first wall segment that is parallel to the first end wall and perpendicular to the inboard wall. An angled wall segment angles toward the first end wall and the outboard wall. A transition wall segment is connected to the angled wall segment. The transition wall segment is parallel to the inboard wall and the outboard wall. A second end wall segment is connected to the transition wall and the outboard wall. The second end wall segment is parallel to the first end wall. In at least one embodiment, the outboard wall is a portion of an outboard wall of the internal cabin. 
     In at least one embodiment, the first lavatory unit includes a first passage that connects to an aisle of the internal cabin. A first door is configured to open and close the first passage. The second lavatory unit includes a second passage that connects to an egress path of the internal cabin. A second door is configured to open and close the second passage. 
     In at least one embodiment, the first lavatory unit has a first length and the second lavatory unit has a second length. The first length is greater than the second length. 
     In at least one embodiment, the lavatory system also includes a divider wall within the interior chamber. The divider wall separates the first lavatory unit from the second lavatory unit. In at least one example, the divider wall is moveable between a closed position that separates the interior chamber into the first lavatory unit and the second lavatory unit, and an open position, in which the interior chamber provides an enlarged, expanded single lavatory space. 
     The first lavatory unit includes a first sink and a first toilet and/or urinal. The second lavatory unit includes a second sink and a second toilet. 
     In an example, the lavatory system also includes a barrier moveably coupled to one of the first lavatory unit or the second lavatory unit. The barrier is moveable between an extended position and a retracted position. The barrier in the extended position is disposed in front of an exit door of the vehicle. The exit door is visible within the internal cabin when the barrier is in the retracted position. The barrier may include a handle that is configured to be grasped to move the barrier between the extended position and the retracted position. The barrier may include a sign that indicates a location of one or both of the first lavatory unit or the second lavatory unit. 
     In at least one embodiment, the lavatory system also includes a storage compartment extending outwardly from an outer wall of one or both of the first lavatory unit or the second lavatory unit. The storage compartment defines an internal storage space that connects to the interior chamber. For example, the storage compartment is at least a portion of a stowage bin assembly. As another example, the storage compartment is at least a portion of an end cap connected to a stowage bin assembly. 
     A storage access door may be disposed between the storage compartment and the interior chamber. The storage access door is configured to be moved between an open position and a closed position. The internal storage space is opened to the interior chamber when the storage access door is in the open position. The internal storage space is closed to the interior chamber when the storage access door is in the closed position. In at least one embodiment, the storage compartment is directly connected to the interior chamber, but is not within the interior chamber. 
     An access opening connects the internal storage space to the interior chamber. The access opening may be formed through the outer wall. 
     The storage compartment may include a lighting assembly within the internal storage space. For example, the lighting assembly is operatively coupled to a storage access door of the storage compartment. The lighting assembly is configured to activate to illuminate the interior storage space when the storage access door is opened. The lighting assembly is configured to be deactivated when the storage access door is closed. 
     In at least one embodiment, the lavatory system also includes a containment compartment common to the first lavatory unit and the second lavatory unit. For example, the containment compartment extends through a divider wall that separates the first lavatory unit from the second lavatory unit. 
     In at least one embodiment, the containment compartment includes a first interior end wall within the first lavatory unit, a front wall, a rear wall, a base, an upper counter, and a second interior end wall opposite from the first interior end wall. The second interior end wall is within the second lavatory unit. The first interior end wall, the front wall, the rear wall, the base, the upper counter, and the second interior end wall define a containment chamber of the containment compartment. A trash container may be stored within the containment compartment. 
     In at least one embodiment, the containment compartment also includes an access door within one of the first lavatory unit or the second lavatory unit. The access door is moveable between an open position and a closed position. The containment compartment is exposed when the access door is in the open position. The containment compartment is closed when the access door is in the closed position. 
     In at least one embodiment, the lavatory system also includes a first trash opening in the first lavatory unit. The first trash opening leads to a containment chamber of the containment compartment. A second trash opening is in the second lavatory unit. The second trash opening leads to the containment chamber of the containment compartment. As a further example, a first trash duct is connected to the first trash opening, and a second trash duct is connected to the second trash opening. 
     Certain embodiments of the present disclosure provide a method of forming a lavatory system within an internal cabin of a vehicle. The method includes providing an enclosure defining an interior chamber, forming a first lavatory unit within the interior chamber, and forming a second lavatory within the interior chamber. The first lavatory unit is adjacent to the second lavatory unit. 
     Certain embodiments of the present disclosure provide a vehicle including an internal cabin having an aisle and an egress path, and a lavatory system within the internal cabin, as described herein. 
     Certain embodiments of the present disclosure provide a lavatory within an internal cabin of a vehicle. The lavatory includes an interior chamber defined by one or more outer walls, and a storage compartment extending outwardly from at least one of outer walls. The storage compartment defines an internal storage space that connects to the interior chamber. The lavatory may be at least one lavatory unit of a lavatory system. 
     As an example, the storage compartment is at least a portion of a stowage bin assembly. As another example, the storage compartment is at least a portion of an end cap connected to a stowage bin assembly. 
     The lavatory may also include a storage access door disposed between the storage compartment and the interior chamber. The storage access door is configured to be moved between an open position and a closed position. The internal storage space is opened to the interior chamber when the storage access door is in the open position. The internal storage space is closed to the interior chamber when the storage access door is in the closed position. 
     In at least one embodiment, the storage compartment is directly connected to the interior chamber, but is not within the interior chamber. 
     As an example, an access opening connects the internal storage space to the interior chamber. The access opening is formed through the one or more outer walls. 
     The storage compartment may include a lighting assembly within the internal storage space. The lighting assembly is operatively coupled to a storage access door of the storage compartment. For example, the lighting assembly is configured to activate to illuminate the interior storage space when the storage access door is opened. The lighting assembly is configured to be deactivated when the storage access door is closed. 
     Certain embodiments of the present disclosure provide a method of forming a lavatory within an internal cabin of a vehicle. The method includes defining an interior chamber of the lavatory by one or more outer walls, extending a storage compartment outwardly from at least one of the outer walls, and connecting an internal storage space of the storage compartment to the interior chamber. 
     Certain embodiments of the present disclosure provide a vehicle including an internal cabin, and a lavatory within an internal cabin of a vehicle, as described herein. 
     Certain embodiments of the present disclosure provide a lavatory system within an internal cabin of a vehicle. The lavatory system includes a first lavatory unit, a second lavatory adjacent to the first lavatory unit, and a containment compartment common to the first lavatory unit and the second lavatory unit. 
     In at least one embodiment, the containment compartment extends through a divider wall that separates the first lavatory unit from the second lavatory unit. 
     As an example, the containment compartment includes a first interior end wall within the first lavatory unit, a front wall, a rear wall, a base, an upper counter, and a second interior end wall opposite from the first interior end wall. The second interior end wall is within the second lavatory unit. The first interior end wall, the front wall, the rear wall, the base, the upper counter, and the second interior end wall define a containment chamber of the containment compartment. A trash container may be stored within the containment compartment. 
     In at least one embodiment, the containment compartment includes an access door within one of the first lavatory unit or the second lavatory unit. The access door is moveable between an open position and a closed position. The containment compartment is exposed when the access door is in the open position. The containment compartment is closed when the access door is in the closed position. 
     In at least one embodiment, a first trash opening in the first lavatory unit. The first trash opening leads to a containment chamber of the containment compartment. A second trash opening is in the second lavatory unit. The second trash opening leads to the containment chamber of the containment compartment. As a further example, a first trash duct is connected to the first trash opening, and a second trash duct connected to the second trash opening. 
     Certain embodiments of the present disclosure provide a method of forming a lavatory system within an internal cabin of a vehicle. The method includes providing a containment compartment common to a first lavatory unit and a second lavatory unit that is adjacent to the first lavatory unit. 
     Certain embodiments of the present disclosure provide a vehicle including a containment compartment, as described herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a perspective front view of an aircraft, according to an embodiment of the present disclosure. 
         FIG. 2A  illustrates a top plan view of an internal cabin of an aircraft, according to an embodiment of the present disclosure. 
         FIG. 2B  illustrates a top plan view of an internal cabin of an aircraft, according to an embodiment of the present disclosure. 
         FIG. 3  illustrates a perspective interior view of an internal cabin of an aircraft, according to an embodiment of the present disclosure. 
         FIG. 4  illustrates a perspective internal view of a lavatory within an internal cabin of an aircraft. 
         FIG. 5  illustrates a top view of a lavatory system within an internal cabin, according to an embodiment of the present disclosure. 
         FIG. 6  illustrates a top view of a lavatory system within an internal cabin, according to an embodiment of the present disclosure. 
         FIG. 7  illustrates a top view of a lavatory system within an internal cabin, according to an embodiment of the present disclosure. 
         FIG. 8  illustrates a top view of a lavatory system within an internal cabin, according to an embodiment of the present disclosure. 
         FIG. 9  illustrates a perspective view of a lavatory system proximate to an exit door, according to an embodiment of the present disclosure. 
         FIG. 10  illustrates a front view of a barrier in an extended position, according to an embodiment of the present disclosure. 
         FIG. 11  illustrates a perspective view of a lavatory connected to a row of overhead stowage bin assemblies, according to an embodiment of the present disclosure. 
         FIG. 12  illustrates a perspective view of a storage compartment extending outwardly from the lavatory, according to an embodiment of the present disclosure. 
         FIG. 13  illustrates a perspective internal view of a containment compartment for a first lavatory connected to a second lavatory, according to an embodiment of the present disclosure. 
         FIG. 14  illustrates a simplified front view of the containment compartment common to the first lavatory and the second lavatory, according to an embodiment of the present disclosure. 
         FIG. 15  illustrates a simplified front view of the containment compartment common to the first lavatory and the second lavatory, according to an embodiment of the present disclosure. 
         FIG. 16  illustrates a flow chart of a method of forming a lavatory system within an internal cabin of a vehicle, according to an embodiment of the present disclosure. 
         FIG. 17  illustrates a flow chart of a method of forming a lavatory within an internal cabin of a vehicle, according to an embodiment of the present disclosure. 
         FIG. 18  illustrates a block diagram of a method of forming a lavatory within an internal cabin of a vehicle, according to an embodiment of the present disclosure. 
         FIG. 19  illustrates a top view of a lavatory system within an internal cabin, according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     The foregoing summary, as well as the following detailed description of certain embodiments will be better understood when read in conjunction with the appended drawings. As used herein, an element or step recited in the singular and preceded by the word “a” or “an” should be understood as not necessarily excluding the plural of the elements or steps. Further, references to “one embodiment” are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising” or “having” an element or a plurality of elements having a particular condition can include additional elements not having that condition. 
     Certain embodiments of the present disclosure provide a lavatory system including two lavatory units within a common enclosure, such as a single, common, monument. The lavatory units are arranged so as to displace only a single three seat assembly unit. In at least one embodiment, the lavatory system is located proximate to an end of a column of seats and an exit doorway. The lavatory system allows aircraft operators to have four lavatories (two lavatories per lavatory system) within an area, and at the same time retain as many as eighteen passenger seats, as compared to conventional lavatories within a commercial aircraft. As such, embodiments of the present disclosure provide lavatory systems that allow for aircraft operators to maintain or even increase revenue-generating passenger seats within an internal cabin. 
       FIG. 1  illustrates a perspective front view of an aircraft  10 , according to an embodiment of the present disclosure. The aircraft  10  includes a propulsion system  12  that includes engines  14 , for example. Optionally, the propulsion system  12  may include more engines  14  than shown. The engines  14  are carried by wings  16  of the aircraft  10 . In other embodiments, the engines  14  may be carried by a fuselage  18  and/or an empennage  20 . The empennage  20  may also support horizontal stabilizers  22  and a vertical stabilizer  24 . 
     The fuselage  18  of the aircraft  10  defines an internal cabin  30 , which includes a flight deck or cockpit, one or more work sections (for example, galleys, personnel carry-on baggage areas, and the like), one or more passenger sections (for example, first class, business class, and coach sections), one or more lavatories, and/or the like. The internal cabin  30  includes one or more lavatory systems, lavatory units, or lavatories, as described herein. 
     Alternatively, instead of an aircraft, embodiments of the present disclosure may be used with various other vehicles, such as automobiles, buses, locomotives and train cars, watercraft, and the like. Further, embodiments of the present disclosure may be used with respect to fixed structures, such as commercial and residential buildings. 
       FIG. 2A  illustrates a top plan view of an internal cabin  30  of an aircraft, according to an embodiment of the present disclosure. The internal cabin  30  may be within the fuselage  32  of the aircraft, such as the fuselage  18  of  FIG. 1 . For example, one or more fuselage walls may define the internal cabin  30 . The internal cabin  30  includes multiple sections, including a front section  33 , a first class section  34 , a business class section  36 , a front galley station  38 , an expanded economy or coach section  40 , a standard economy of coach section  42 , and an aft section  44 , which may include multiple lavatories and galley stations. It is to be understood that the internal cabin  30  may include more or less sections than shown. For example, the internal cabin  30  may not include a first class section, and may include more or less galley stations than shown. Each of the sections may be separated by a cabin transition area  46 , which may include class divider assemblies between aisles  48 . 
     As shown in  FIG. 2A , the internal cabin  30  includes two aisles  50  and  52  that lead to the aft section  44 . Optionally, the internal cabin  30  may have less or more aisles than shown. For example, the internal cabin  30  may include a single aisle that extends through the center of the internal cabin  30  that leads to the aft section  44 . 
     The aisles  48 ,  50 , and  52  extend to egress paths or door passageways  60 . Exit doors  62  are located at ends of the egress paths  60 . The egress paths  60  may be perpendicular to the aisles  48 ,  50 , and  52 . The internal cabin  30  may include more egress paths  60  at different locations than shown. As described herein, lavatory systems may be located at or proximate to intersections of the aisles  48 ,  50 ,  52  and the egress paths  60 . 
       FIG. 2B  illustrates a top plan view of an internal cabin  80  of an aircraft, according to an embodiment of the present disclosure. The internal cabin  80  is an example of the internal cabin  30  shown in  FIG. 1 . The internal cabin  80  may be within a fuselage  81  of the aircraft. For example, one or more fuselage walls may define the internal cabin  80 . The internal cabin  80  includes multiple sections, including a main cabin  82  having passenger seats  83 , and an aft section  85  behind the main cabin  82 . It is to be understood that the internal cabin  80  may include more or less sections than shown. 
     The internal cabin  80  may include a single aisle  84  that leads to the aft section  85 . The single aisle  84  may extend through the center of the internal cabin  80  that leads to the aft section  85 . For example, the single aisle  84  may be coaxially aligned with a central longitudinal plane of the internal cabin  80 . 
     The aisle  84  extends to an egress path or door passageway  90 . Exit doors  92  are located at ends of the egress path  90 . The egress path  90  may be perpendicular to the aisle  84 . The internal cabin  80  may include more egress paths than shown. As described herein, lavatory systems may be located at or proximate to intersections of the aisle  84  and one or more egress paths  90 . 
       FIG. 3  illustrates a perspective interior view of an internal cabin  100  of an aircraft, according to an embodiment of the present disclosure. The internal cabin  100  is an example of the internal cabin  30 , shown in  FIG. 1 . The internal cabin  100  includes outboard walls  102  connected to a ceiling  104 . Windows  106  may be formed within the outboard walls  102 . A floor  108  supports rows of seats  110 . As shown in  FIG. 3 , a row  112  may include two seats  110  on either side of an aisle  113 . However, the row  112  may include more or less seats  110  than shown. Additionally, the internal cabin  100  may include more aisles than shown. 
     Passenger service units (PSUs)  114  are secured between an outboard wall  102  and the ceiling  104  on either side of the aisle  113 . The PSUs  114  extend between a front end and rear end of the internal cabin  100 . For example, a PSU  114  may be positioned over each seat  110  within a row  112 . Each PSU  114  may include a housing  116  that generally contains vents, reading lights, an oxygen bag drop panel, an attendant request button, and other such controls over each seat  110  (or groups of seats) within a row  112 . 
     Overhead stowage bin assemblies  118  are secured to the ceiling  104  and/or the outboard wall  102  above and inboard from the PSU  114  on either side of the aisle  113 . The overhead stowage bin assemblies  118  are secured over the seats  110 . The overhead stowage bin assemblies  118  extend between the front and rear end of the internal cabin  100 . Each stowage bin assembly  118  may include a pivot bin or bucket  120  pivotally secured to a strongback (hidden from view in  FIG. 3 ). The overhead stowage bin assemblies  118  may be positioned above and inboard from lower surfaces of the PSUs  114 . The overhead stowage bin assemblies  118  are configured to be pivoted open in order to receive passenger carry-on baggage and personal items, for example. 
     As used herein, the term “outboard” means a position that is further away from a central longitudinal plane  122  of the internal cabin  100  as compared to another component. The term “inboard” means a position that is closer to the central longitudinal plane  122  of the internal cabin  100  as compared to another component. For example, a lower surface of a PSU  114  may be outboard in relation to a stowage bin assembly  118 . 
       FIG. 4  illustrates a perspective internal view of a lavatory  130  within an internal cabin of a vehicle, such as any of the internal cabins described herein. The lavatory  130  is an example of an enclosed space, monument or chamber, such as within the internal cabin of the aircraft  10 , shown in  FIG. 1 . The lavatory  130  may be onboard an aircraft, as described above. Optionally, the lavatory  130  may be onboard various other vehicles. In other embodiments, the lavatory  130  may be within a fixed structure, such as a commercial or residential building. The lavatory  130  includes a base floor  131  that supports a toilet  132  (and/or a urinal), cabinets  134 , and a sink  136  or wash basin. The lavatory  130  may be arranged differently than shown. The lavatory  130  may include more or less components than shown. 
       FIG. 5  illustrates a top view of a lavatory system  150  within an internal cabin  152 , according to an embodiment of the present disclosure. The lavatory system  150  may be used within any of the internal cabins described herein, such as the internal cabins shown and described with respect to  FIGS. 1-3 . 
     The lavatory system  150  includes a single enclosure  154  (such as a monument) that includes a first lavatory unit  156  adjacent to a second lavatory unit  158 . That is, the lavatory system  150  is a single monument. The first lavatory unit  156  and the second lavatory unit  158  are disposed laterally across a portion of the internal cabin  152 , instead of longitudinally along an aisle  160 . That is, the first lavatory unit  156  and the second lavatory  158  are side-to-side across a portion of the internal cabin  152 , instead of end-to-end along a length of the internal cabin  152 . In this manner, the lavatory system  150  extends over a smaller longitudinal portion (such as one longitudinal area  162 ) of the internal cabin  152 , instead of an extended longitudinal portion (for example, two longitudinal areas (such as if the first lavatory unit  156  and the second lavatory unit  158  were end-to-end)), thereby freeing up additional space for other components, such as another monument (such as a galley), or additional passenger seats (such as a three seat assembly), which generate revenue for an aircraft operator. 
     The lavatory system  150  provides two lavatory units, such as the first lavatory unit  156  and the second lavatory unit  158 , while displacing only a single seating assembly having three passenger seats. The side-to-side configuration of the first and second lavatory units  156  and  158  provides multiple lavatory units while allowing for additional passenger seating, for example (in contrast to lavatories that are disposed end-to-end). In at least one embodiment, the lavatory system  150  provides multiple lavatory units within the space of a three seating unit passenger seating assembly. 
     The first lavatory unit  156  is an inboard lavatory unit, and the second lavatory unit  158  is an outboard lavatory unit. It is to be understood that the terms first and second are merely for labeling purposes. A first lavatory unit may be a second lavatory unit, and vice versa. 
     The single enclosure (such as a monument)  154  that defines the lavatory system  150  includes a first end wall  164  (or first system end wall) that connects to an inboard wall  166  (or system inboard wall) facing the aisle  160 . The inboard wall  166  connects to a second end wall  168  (or second system end wall) opposite from the first end wall  164 . The second end wall  168  faces an egress path  170  that connects to the aisle  160 . In at least one embodiment, the second end wall  168  includes a first wall segment  172  that may be parallel to the first end wall  164  (and perpendicular to the inboard wall  166 ). The first wall segment  172  connects to an angled wall segment  174  that angles toward the first end wall  164  and an outboard wall  176  (or system outboard wall) that connects to the first end wall  164  and the second end wall  168 . The angled wall segment  174 , in turn, connects to a transition wall segment  176 , which may be parallel to the inboard wall  166  and the outboard wall  178 . The transition wall segment  178  connects to a second wall segment  180 , which may be parallel to the first end wall  164  and perpendicular to the outboard wall  176 . Optionally, the angled wall segment  174  may connect directly to the second wall segment  180  without the transition wall segment  178 . The second wall segment  180  connects to the outboard wall  178 . 
     In at least one embodiment, the outboard wall  176  is a portion of an outboard wall of the internal cabin  152 , such as the outboard wall  102  shown in  FIG. 3 . That is, the outboard wall  102 , in part, defines the internal cabin  152 . Using a portion of the outboard wall of the internal cabin  152  to provide the outboard wall  176  provides increased interior space within the lavatory system  150 . In at least one other embodiment, the outboard wall  176  is a separate wall that abuts against or is otherwise proximate to the outboard wall of the internal cabin  152 . 
     The first end wall  164 , the inboard wall  166 , the second end wall  168  and the outboard wall  176  define the outer perimeter of the enclosure  154  (and the monument  155 ), and an interior chamber  182  of the lavatory system  150 . That is, the enclosure  154  defines the interior chamber  182 . The enclosure  154  is within the internal cabin  152 . The enclosure  154  is not the internal cabin  152 . For example, an internal cabin may include multiple lavatories. However, the internal cabin  152  includes the enclosure  154 , which includes the first lavatory unit  156  and the second lavatory unit  158  within the interior chamber  182  of the enclosure  154  (in contrast to two distinct lavatories abutting one another). The enclosure  154  includes the first lavatory unit  156  and the second lavatory unit  158  within the interior chamber  182 . The first lavatory unit  156  and the second lavatory unit  158  are within the interior chamber  182 . 
     The first lavatory unit  156  includes a passage  184  that connects to the aisle  160 . A door  186  is moveably coupled to the first end wall  164  and/or the inboard wall  166 . The door  186  faces the aisle  160  and is configured to be moved between a closed position, in which the passage  184  is closed to the aisle  160 , and an open position, in which the passage  184  is open to the aisle  160 . When the door  186  is in the open position, an individual may pass between the aisle  160  and the first lavatory unit  156  through the passage  184 . 
     The second lavatory unit  158  includes a passage  188  that connects to the egress path  170 . A door  190  is moveably coupled to the second end wall  168  (such as the second wall segment  180 , and/or the outboard wall  176 . The door  190  faces the egress path  170  and is configured to be moved between a closed position, in which the passage  188  is closed to the egress path  170 , and an open position, in which the passage  188  is open to the egress path  170 . When the door  190  is in the open position, an individual may pass between the egress path  170  and the second lavatory unit  158  through the passage  188 . 
     In at least one embodiment, a length  192  of the first lavatory unit  156  is greater than a length  194  of the second lavatory unit  158 . For example, the first lavatory unit  156  may extend along a greater longitudinal length of the aisle  160  than the second lavatory unit  158 . As such, the second wall segment  180  including the passage  188  of the second lavatory unit  158  may be recessed further toward the first end wall  164  as compared to the first wall segment  172 . 
     A divider wall  196  is disposed within the interior chamber  182  and extends between the first end wall  164  and the second end wall  168 . The divider wall  196  separates the first lavatory unit  156  from the second lavatory unit  158 . The divider wall  196  may include a first divider segment  198  that may be perpendicular to the first end wall  174 . The first divider segment  198  connects to an angled divider segment  200  that angles toward the inboard wall  166  and the first wall segment  172 . The angled divider segment  200  connects to a second divider segment  202  that may be parallel to the first divider segment  198 . The second divider segment  202  may connect to the transition wall segment  178  and/or another portion of the second end wall  168 . 
     In at least one embodiment, the first lavatory unit  156  is defined between the inboard wall  166 , the first wall segment  172 , the angled wall segment  174 , the transition wall segment  178 , a first side  204  of the divider wall  196 , and an inboard segment  165  (that is, the portion inboard from the divider wall  196 ) of the first end wall  164 . The second lavatory unit  158  is defined between the outboard wall  176 , an outboard segment  167  (that is, the portion outboard from the divider wall  196 ) of the first end wall  164 , a second side  206  (opposite from the first side  204 ) of the divider wall  196 , and the second wall segment  180  of the second end wall  168 . 
     The first lavatory unit  156  includes a first sink  208  and a first toilet  210  with a first standing space  212  in front of the first toilet  210 . The first sink  208  may be located at or proximate to a corner  209  defined by the first side  204  of the divider wall  196  and the inboard segment  165  of the first end wall  164 . The first toilet  210  may be located at or proximate to a corner  211  defined by the inboard wall  166  and the second end wall  168 . The term toilet as used herein includes one or both of standard toilet or a urinal. 
     The second lavatory unit  158  includes a second sink  214  and a second toilet  216  with a second standing space  218  in front of the second toilet  216 . The second sink  214  may be located at or proximate to a corner  213  defined by the second side  206  of the divider wall  196  and the second wall segment  180  of the second end wall  168 . The second toilet  216  may be located at or proximate to a corner  215  defined by the outboard wall  176  and the outboard segment  167  of the first end wall  164 . 
     The configurations of the sinks and toilets of the first lavatory unit  156  and the second lavatory unit  158  shown in  FIG. 5  are merely exemplary. The sinks and toilets may be located at various other areas than shown. 
     In at least one embodiment, a flight attendant assist space  220  is located in front of the second wall segment  180  of the second end wall  168 , such as in front of the passage  188 . The flight attendant assist space  220  may be proximate to an exit door at an end of the egress path  170 . The flight attendant assist space  220  is an open area in which a flight attendant may stand to assist individuals entering and exiting the egress path  170 . The second lavatory unit  158  is sized and configured to preserve a defined required area (such as a 12″×20″ area) for the flight attendant assist space, such as may be required by a regulatory agency (for example, the United States Federal Aviation Administration). The angled wall segment  174  may provide an egress flow director that guides and directs individuals toward the exit door when leaving the internal cabin  152 , and toward the aisle  160  when entering the internal cabin  152 . 
       FIG. 6  illustrates a top view of the lavatory system  150  within the internal cabin  152 , according to an embodiment of the present disclosure. In this embodiment, the first sink  208  of the first lavatory unit  156  may be coupled to the first side  204  of the divider wall  196  at an intermediate location between the first end wall  164  and the second end wall  168 , and the second sink  214  may be coupled to the outboard wall  176 . The configurations of the sinks and toilets of the first lavatory unit  156  and the second lavatory unit  158  shown in  FIG. 6  are merely exemplary. The sinks and toilets may be located at various other areas than shown. 
       FIG. 7  illustrates a top view of the lavatory system  150  within the internal cabin  152 , according to an embodiment of the present disclosure. The lavatory system  150  shown in  FIG. 7  is similar to that shown in  FIG. 5 , except that the divider wall  196  may be configured to be moved between a closed position, which separates the interior chamber  182  into the defined first lavatory unit  156  and the second lavatory unit  158 , and an open position, in which the interior chamber  182  provides an enlarged, expanded single lavatory space, which is easily and comfortably accessible by persons of limited mobility. The first sink  208 , the first toilet  210 , the second sink  214 , and the second toilet  216  may not be connected to moveable portions of the divider wall  196 . For example, the divider wall  196  may include a plurality of foldable segments  230  coupled together through hinges  232  that allow the divider wall  196  to be folded and disconnected from one or both of the first end wall  166  and the second end wall  168 . In this manner, the divider wall  196  is foldable or otherwise collapsible. The divider wall  196  in the collapsed position may be secured against an interior wall, and/or removed and stored within the lavatory system  150  or another portion of the internal cabin  152 . As another example, the divider wall  196  may be configured to telescope between open and closed positions. As another example, the divider wall  196  may be configured to slide between open and closed positions. As another example the divider wall  196  may be a curtain or drape, which may include sound-dampening elements. In short, the divider wall  196  may be a movable wall having segments that are configured to move in order to allow the divider wall  196  to be moved between open and closed positions. 
       FIG. 8  illustrates a top view of the lavatory system  150  within the internal cabin  152 , according to an embodiment of the present disclosure. The lavatory system  150  shown in  FIG. 8  is similar to that shown in  FIG. 6 , except that the divider wall  196  may be configured to be moved between a closed position, which separates the interior chamber  182  into the defined first lavatory unit  156  and the second lavatory unit  158 , and an open position, in which the interior chamber  182  provides an enlarged, expanded single lavatory space, which is easily and comfortably accessible by persons of limited mobility, as described with respect to  FIG. 7 . 
       FIG. 19  illustrates a top view of a lavatory system  150  within an internal cabin, according to an embodiment of the present disclosure. In this embodiment, the lavatory system  150  includes divider wall  196  having one or more sliding or telescoping segments  197 . 
     Referring to  FIGS. 5-8 and 19 , the lavatory system  150  allows for the space of three passenger seats to be occupied by two lavatory units. Traditional lavatories consume approximately 20% to 30% more longitudinal space than a passenger seat, resulting in six to twelve passenger seats displaced for two lavatories to be installed. A traditional lavatory area size ranges between 10.8 to 13.4 square feet. In contrast, the lavatory system  150  as described herein provides two lavatory units, such as within a thirteen square foot area, which may be the same or similar area of a single triple passenger seat assembly (60″×32″). 
     In at least one embodiment, the lavatory system  150  may located at an end of a column of seats proximate to an exit doorway. The second (or outboard) lavatory unit  158  opens to the egress path  170  such as a lateral exit passageway into the preserved space used during by flight attendants during emergency evacuations (the lavatory is not in use during this critical time). The first (or inboard) lavatory unit  156  opens to the aisle  160  or alternatively to the same egress path  170 . As an option, the first lavatory unit  156  may extend longitudinally further than the second lavatory unit  158  because the first lavatory unit  156  is inboard of the flight attendant assist space  220 . 
       FIG. 9  illustrates a perspective view of the lavatory system  150  proximate to an exit door  260 , such as that of an aircraft, according to an embodiment of the present disclosure. The exit door  260  is at an end of the egress path  170 . As an option, the lavatory system  150  may include a moveable barrier  262  that is moveably coupled to the second lavatory unit  158 . The barrier  262  can be a panel, wall, screen, door, curtain, or the like that is configured to be moved between an extended position, as shown in  FIG. 9 , in which the barrier  262  is disposed in front of the exit door  260 , and a retracted position, in which the exit door  260  is visible within the internal cabin  152 . 
     The barrier  262  can be movably coupled to the second lavatory unit  158 , another portion of the lavatory system  150 , or a portion of the internal cabin, such as through hinges, slides and tracks, or the like. For example, the barrier  262  is configured to pivot between the extended position and the retracted position, such as about one or more hinges. As another example, the barrier  262  is configured to slide between the extended position and the retracted position. As another example, the barrier  262  is configured to unfold and fold between the extended position and the retracted position. 
     As passengers are entering and exiting the internal cabin  152 , such as into the egress path  170  through the exit door  260  in the opened position, the barrier  262  is in the retracted position. During a flight, the barrier  262  is moved to the extended position, as shown in  FIG. 9 . In the extended position, the barrier  262  conceals the exit door  260 , or at least a portion thereof (such as a handle  264 ), which protects the exit door  260  from being touched, and may assure certain individuals that there is no risk of the handle  264  being inadvertently grasped. 
       FIG. 10  illustrates a front view of the barrier  262  in the extended position, according to an embodiment of the present disclosure. The barrier  262  can include a handle  270 , which may be grasped to move the barrier  262  between the extended and retracted positions. The barrier  262  can also include a sign  272  that indicates a location of the second lavatory unit  158  (shown in  FIG. 9 ), particularly because the door of the second lavatory unit  158  may be hidden from the view by an extended portion of the first lavatory unit  156 . The sign  272  can be painted or printed on the barrier  262 . As another example, the sign  272  can be a decal. As another example, the sign  272  can be a plate or panel mounted on the barrier  262 . As another example, the sign  272  can be illuminated, such as through one or more light assemblies. 
     The barrier  262  may be used with any of the lavatory systems  150  described herein. Optionally, the lavatory systems  150  may not include the barrier  262 . 
       FIG. 11  illustrates a perspective view of a lavatory  300  connected to a row  302  of overhead stowage bin assemblies  304  (such as the stowage bin assemblies  118  shown in  FIG. 3 ), according to an embodiment of the present disclosure. The lavatory  300  may be the lavatory systems  150 , as described herein. For example, the lavatory  300  may be the second lavatory unit  156 , as shown in  FIGS. 5-9 . As another example, the lavatory  300  may be a single unit lavatory, whether or not part of the lavatory system  150  described herein. 
     A portion of the row  302  directly connects to the lavatory  300 , such as a fore or aft end of the lavatory  300 . For example, a stowage bin assembly  304  may directly connect to the lavatory  300 , such as at an upper portion  306  of the lavatory  300 . As another example, an end cap  308  of the row  302  connects a stowage bin assembly  304  to the lavatory  300 . 
     The end cap  308  and/or a stowage bin assembly  304  provides a storage compartment  310  that extends outwardly from an outer wall  312  of the lavatory  300 , such as at an upper overhead portion that is aligned with the stowage bin assemblies  304 . The storage compartment  310  defines an internal storage space  314  that connects to an interior chamber  316  of the lavatory  300 . One or more outer walls (including the outer wall  312 ) defines the interior chamber  316 . The storage compartment  310  extends outwardly from one or more of the outer walls. That is, the storage compartment  310  is not within the interior chamber  316 . In this manner, the storage compartment  310  may replace one or more cabinets that would otherwise be within the lavatory  300 , thereby freeing up additional space within the lavatory  300 . 
     A moveable compartment or storage access door may be disposed between the storage compartment  310  and the interior chamber  316  of the lavatory  300 . The storage access door is moveable between an open position, in which the internal storage space  314  is opened to the interior chamber  316 , and a closed position, in which the internal storage space is closed to the interior chamber  316 . Various supplies, such as toilet papers, facial tissue, and the like, may be stored within the internal storage space  314 , instead of within the interior chamber  316  of the lavatory  300 . 
     As shown, the storage compartment  310  directly connects to the interior chamber  316  of the lavatory  300 , but is not within the interior chamber  316 . Instead, the storage compartment  310  may be part of the end cap  308  and/or a stowage bin assembly  304  outside of the interior chamber  316  of the lavatory  300 . The internal storage space  314  of the storage compartment  310  is accessible from within the interior chamber  316  of the lavatory  300 . By recessing cabinet space into the end cap  308  and/or an overhead stowage bin assembly  304 , more space (which may otherwise be occupied by one or more cabinets) is created within the interior chamber  316 . In general, the storage compartment  310  coupled to the lavatory  300  reduces a need for cabinet space within the lavatory  300 . 
       FIG. 12  illustrates a perspective view of the storage compartment  310  extending outwardly from the lavatory  300 , according to an embodiment of the present disclosure. As noted, the storage compartment  310  may be at least part of an end cap coupled to a stowage bin assembly, or optionally at least part of a stowage bin assembly. An access opening  320  connects the internal storage space  314  of the storage compartment  310  to the interior chamber  316  of the lavatory  300 . The access opening  320  may be formed through a wall  322  of the lavatory  300 , such as a fore or aft wall. 
     A storage access door  324  is moveably coupled to the storage compartment  310  and/or the wall  322 . The storage access door  324  is moveable between an open position and a closed position. The storage access door  324  may pivot about one or more hinges, slides over one or more tracks, and/or the like between the open position and the closed position. 
     In at least one embodiment, a lighting assembly  326  may be disposed within the storage compartment  310 . The lighting assembly  326  is configured to illuminate the interior storage space  314 . In at least one embodiment, the lighting assembly  326  is operatively coupled to the storage access door  324 , such as through a switch  328 , for example. In this manner, the lighting assembly  326  may be activated to illuminate the interior storage space  314  when the storage access door  324  is opened, and deactivated when the storage access door  324  is closed. 
     The storage compartment  310  may be used with any of the embodiments described herein. For example, the storage compartment  310  may be connected to any of the lavatories or lavatory units described herein. 
       FIG. 13  illustrates a perspective internal view of a containment compartment  300  for a first lavatory  302  connected to a second lavatory  304 , according to an embodiment of the present disclosure. A lavatory system  301  includes the first lavatory  302 , the second lavatory  304 , and the containment compartment  300  that is common to (for example, shared by) the first lavatory  302  and the second lavatory  304 . The containment compartment  300  defines a containment chamber  303 . In at least one embodiment, the first lavatory  302  is the first lavatory unit  156 , and the second lavatory  304  is the second lavatory  158 , as shown and described with respect to  FIGS. 5-9 , for example. Optionally, the first lavatory  302  and the second lavatory  304  may be other than the first lavatory  156  and the second lavatory unit  304 . 
     The first lavatory  302  is separated from the second lavatory  304  by a divider wall  306 . For example, the divider wall  306  may be the divider wall  196 , as shown and described with respect to  FIGS. 5-9 . 
     The first lavatory  302  includes a first housing  308  (such as a first cabinet) and the second lavatory  310  includes a second housing  310  (such as a second cabinet). The containment compartment  300  is common to both the first lavatory  302  and the second lavatory  310 . The containment compartment  300  extends through the divider wall  196 . 
     The containment compartment  300  includes a first interior end wall  312  that connects to a front wall  314 , a rear wall  316 , a base  318 , and an upper counter  320  that extend between (and/or form portions of) the first housing  308  and the second housing  310 . The front wall  314 , the rear wall, the base  318 , and the upper counter  320  connect to a second interior end wall  322  opposite from the first interior end wall  312 . The first interior end wall  312  is within the first lavatory  302 , and the second interior end wall  322  is within the second lavatory  304 . The first interior end wall  312  may be part of the first housing  308 , such as a first cabinet, and the second interior end wall  322  may be part of the second housing  310 , such as a second cabinet. 
     The first interior end wall  312 , the front wall  314 , the rear wall  316 , the base  318 , the upper counter  320  (which extends through the divider wall  306 ), and the second interior end wall  322  define the containment chamber  303  of the containment compartment  300 . The containment compartment  300  is common to the first lavatory  302  and the second lavatory  304 . The containment compartment  300  is shared by both the first lavatory  302  and the second lavatory  304 . 
     A trash container  330  is configured to be stored within the containment compartment  300 . An access door  332  is coupled to the front wall  314 , such as within the first lavatory  302 . For example, the access door  332  is moveably coupled to the front wall  312  within first lavatory  302  (or optionally the second lavatory  304 ). The access door  302  is moveably coupled to the front wall  314 , such as through one or more hinges, slides and tracks, and/or the like. As such, the access door  302  is configured to pivotally or slidably move between an open position, in which the containment chamber  303  of the containment compartment  300  is exposed, and a closed position, in which the containment chamber  303  of the containment compartment  300  is closed. When the access door  302  is in the open position, the trash container  330  may be selectively removed and repositioned. 
     A first trash opening  340  having a moveable lid  341  is formed in the upper counter  320  within the first lavatory  302 . A second trash opening  342  having a moveable lid  343  is formed in the upper counter  320  within the second lavatory  302 . The first trash opening  340  and the second trash opening  342  both lead to the containment chamber  303  of the containment compartment  300 , which is common to both the first lavatory  302  and the second lavatory  304 . In this manner, trash disposed within both the first lavatory  302  and the second lavatory  304  may be discarded through the respective first trash opening  340  and the second trash opening  320  into the trash container  330 , which is disposed within the containment chamber  303  of the containment compartment  300 . 
     In at least one embodiment, the containment compartment  300  may be configured to contain a fire therein. For example, interior wall portions that define the containment compartment  300  may be formed of fire retardant materials, and joints between the walls and the access door  332  in the closed position may sealingly engage one another to limit a flow of oxygen into the containment compartment  300  when the access door  332  is closed. Further, the containment compartment  300  may retain a fire suppression device  350 , such as a fire extinguisher, that is shared by the first lavatory  302  and the second lavatory  304 . 
     The containment compartment  300  retains the trash container  330 , which is used by both the first lavatory  302  and the second lavatory  304 , thereby economizing space for both the first lavatory  302  and the second lavatory  304 . In this manner, additional space is provided for both the neighboring first lavatory  302  and the second lavatory  304 . The containment compartment  300  provides access to the single trash container  330  from separate, but neighboring lavatories  302  and  304 , which are separated by the divider wall  306 . 
     The containment compartment  300  may be used with any of the embodiments described herein. For example, the containment compartment  300  may be used with respect to any neighboring lavatories or lavatory units, as described herein. 
       FIG. 14  illustrates a simplified front view of the containment compartment  300  common to the first lavatory  302  and the second lavatory  302 , according to an embodiment of the present disclosure. The containment compartment  300  extends through the divider wall  306  so that a first portion  300   a  of the containment compartment  300   a  is within the first lavatory  302 , and a second portion  300   b  of the containment compartment  300   b  is within the second lavatory  302 . 
     In at least one embodiment, a first container portion  330   a  of the trash container  330  is underneath the first trash opening  340 , and a second container portion  330 b of the trash container  330  is underneath the second trash opening  342 . As such, trash passed into and through the first trash opening  340  and the second trash opening  342  is received within a containing chamber  331  of the trash container  330 . 
       FIG. 15  illustrates a simplified front view of the containment compartment  300  common to the first lavatory  302  and the second lavatory  304 , according to an embodiment of the present disclosure. The trash container  330  may not be positioned directly below the first trash opening  340  and/or the second trash opening  342 . As such, a first trash duct  350  may be connected to the first trash opening  340 , and a second trash duct  352  may be connected to the second trash opening  342 . The first trash duct  350  and the second trash duct  352  lead to containing chamber  331  of the trash container  330 . 
       FIG. 16  illustrates a flow chart of a method  400  of forming a lavatory system within an internal cabin of a vehicle. The method  400  includes providing, at  402 , an enclosure defining an interior chamber; forming, at  404 , a first lavatory unit within the interior chamber, and forming, at  406 , a second lavatory within the interior chamber. The first lavatory unit is adjacent to the second lavatory unit. 
     In at least one example, said forming  406  the second lavatory incudes providing a portion of an outboard wall of the internal cabin as an outboard wall of the second lavatory. 
     In at least one example, said forming  404  the first lavatory unit includes connecting a first passage of the first lavatory unit to an aisle of the internal cabin, and said forming  406  the second lavatory unit includes connecting a second passage of the second lavatory unit to an egress path of the internal cabin. 
     In at least one embodiment, the method includes providing a divider wall within the interior chamber, and separating the first lavatory unit from the second lavatory unit with the divider wall. As a further example, the method may include moving the divider wall between a closed position that separates the interior chamber into the first lavatory unit and the second lavatory unit, and an open position, in which the interior chamber provides an enlarged, expanded single lavatory space. 
     As another example, the method includes moveably coupling a barrier to one of the first lavatory unit or the second lavatory unit, and moving the barrier is between an extended position and a retracted position. The barrier in the extended position is disposed in front of an exit door of the vehicle. The exit door is visible within the internal cabin when the barrier is in the retracted position. 
     Optionally, the method includes providing, at  408 , a storage compartment that extends outwardly from an outer wall of one or both of the first lavatory unit or the second lavatory unit. The storage compartment defines an internal storage space that connects to the interior chamber. As another option, the method includes  408  in relation to lavatory system, a lavatory, or lavatory unit, and not steps  402 - 406 . 
     Optionally, the method includes providing, at  410 , a containment compartment that is common to the first lavatory unit and the second lavatory unit. As another option, the method includes  410  in relation to a lavatory system, a lavatory, or lavatory unit, and not steps  402 - 408 . As another option, the method includes steps  408  and  410 , but not steps  402 - 406 . 
       FIG. 17  illustrates a flow chart of a method  500  of forming a lavatory within an internal cabin of a vehicle. The method  500  includes defining, at  502 , an interior chamber of the lavatory by one or more outer walls; extending, at  504 , a storage compartment outwardly from at least one of the outer walls; and connecting, at  506 , an internal storage space of the storage compartment to the interior chamber. 
     In at least one example, the method includes forming at least a portion of a stowage bin assembly as the storage compartment. As another example, the method includes forming at least a portion of an end cap connected to a stowage bin assembly as the storage compartment. 
     In at least one embodiment, the method includes disposing a storage access door disposed between the storage compartment and the interior chamber; and moving the storage access door moved between an open position and a closed position. The internal storage space is opened to the interior chamber when the storage access door is in the open position. The internal storage space is closed to the interior chamber when the storage access door is in the closed position. 
     In at least one embodiment, said extending includes directly connecting the storage compartment to the interior chamber. The storage compartment is not within the interior chamber. 
     As an example, the method includes forming an access opening through the one or more outer walls, and connecting the internal storage space to the interior chamber through the access opening. 
     In at least one embodiment, the method includes providing a lighting assembly within the internal storage space of the storage compartment. As a further example, the method includes operatively coupling the lighting assembly to a storage access door of the storage compartment; activating the lighting assembly to illuminate the interior storage space when the storage access door is opened; and deactivating the lighting assembly when the storage access door is closed. 
       FIG. 18  illustrates a block diagram of a method  600  of forming a lavatory system within an internal cabin of a vehicle. The method  600  includes providing, at  602 , a containment compartment common to a first lavatory unit and a second lavatory unit that is adjacent to the first lavatory unit. 
     In at least one example, the method includes extending the containment compartment through a divider wall that separates the first lavatory unit from the second lavatory unit. 
     In at least one embodiment, the containment compartment includes a first interior end wall within the first lavatory unit, a front wall, a rear wall, a base, an upper counter, and a second interior end wall opposite from the first interior end wall. The second interior end wall is within the second lavatory unit. The first interior end wall, the front wall, the rear wall, the base, the upper counter, and the second interior end wall define a containment chamber of the containment compartment. 
     In at least one embodiment, the method includes storing a trash container within the containment compartment. 
     As another example, the method includes providing an access door within one of the first lavatory unit or the second lavatory unit; and moving the access door between an open position and a closed position. The containment compartment is exposed when the access door is in the open position. The containment compartment is closed when the access door is in the closed position. 
     In at least one embodiment, the method includes forming a first trash opening in the first lavatory unit. The first trash opening leads to a containment chamber of the containment compartment. The method also includes forming a second trash opening in the second lavatory unit. The second trash opening leads to the containment chamber of the containment compartment. As a further example, the method includes connecting a first trash duct to the first trash opening, and connecting a second trash duct to the second trash opening. 
     As an example, the method includes containing the first lavatory unit and the second lavatory unit within a single monument within the internal cabin. 
     As an example, the method includes disposing the first lavatory unit and the second lavatory unit side-to-side across a portion of the internal cabin. 
     Referring to  FIGS. 1-18 , as described herein, embodiments of the present disclosure provide lavatory units that occupy less space than known lavatories within an internal cabin of a vehicle. Further, embodiments of the present disclosure provide lavatory units that are readily and easily accessible by persons of limited mobility. Also, embodiments of the present disclosure provide multi-unit lavatory systems that do not reduce space for additional seating within an internal cabin of a vehicle. 
     While various spatial and directional terms, such as top, bottom, lower, mid, lateral, horizontal, vertical, front and the like can be used to describe embodiments of the present disclosure, it is understood that such terms are merely used with respect to the orientations shown in the drawings. The orientations can be inverted, rotated, or otherwise changed, such that an upper portion is a lower portion, and vice versa, horizontal becomes vertical, and the like. 
     As used herein, a structure, limitation, or element that is “configured to” perform a task or operation is particularly structurally formed, constructed, or adapted in a manner corresponding to the task or operation. For purposes of clarity and the avoidance of doubt, an object that is merely capable of being modified to perform the task or operation is not “configured to” perform the task or operation as used herein. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) can be used in combination with each other. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the various embodiments of the disclosure without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments of the disclosure, the embodiments are by no means limiting and are exemplary embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments of the disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims and the detailed description herein, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. § 112(f), unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure. 
     This written description uses examples to disclose the various embodiments of the disclosure, including the best mode, and also to enable any person skilled in the art to practice the various embodiments of the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the various embodiments of the disclosure is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if the examples have structural elements that do not differ from the literal language of the claims, or if the examples include equivalent structural elements with insubstantial differences from the literal language of the claims.