You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
     The present invention relates to a building-access ramp for physically handicapped individuals, and more particularly to such a ramp which is modular in construction and capable of ready assembly and disassembly. 
     The relatively simple function of entering a building can be extremely difficult for physically handicapped, infirm, and/or aged individuals. Climbing steps is a function which is simply impossible for individuals confined to wheelchairs or even using walkers. Although building codes require new commercial buildings to be &#34;handicap-accessible&#34;, residential construction codes to not include such requirements; and many older commercial buildings remain handicap inaccessible. 
     When an individual desires to provide a handicap access to his home or an existing commercial building, most typically a wooden ramp is erected. Generally speaking, each ramp is unique in design and is permanently attached to the building structure. Construction often results in a relatively large amount of scrap lumber. The cost of constructing a ramp in this fashion is high, requiring a relatively large amount of carpenter time. The ramp is typically torn down when no longer required; and the lumber is generally non-reusable. 
     SUMMARY OF THE INVENTION 
     The aforementioned problems are overcome in the present invention comprising a modular wheelchair ramp capable of ready assembly and disassembly. The ramp includes a supporting frame fabricated substantially exclusively of inexpensive conventional PVC plumbing components and a plurality of wooden ramp sections mounted on the frame. The frame includes a plurality of support or leg assemblies each including a pair of legs and a horizontal crossbar slidably mounted thereon for height adjustability. The leg assemblies are arranged along a ramp path; and the crossbars are adjusted to define an inclined support structure. The wooden ramp sections are installed on the crossbars to complete assembly. 
     The present ramp construction is relatively inexpensive, being fabricated of conventional PVC plumbing parts and wooden ramp sections. Further, the ramp kit can be easily assembled by a single individual, reducing installation cost. Ramp assembly does not result in scrap material since all ramp components are self-contained and put together in &#34;erector set&#34; fashion. Finally, the ramp can also be readily disassembled for movement to a different location. 
     These and other objects, advantages, and features of the invention will be more readily understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the modular ramp of the present invention; 
     FIG. 2 is a top plan view of the ramp; 
     FIG. 3 is a fragmentary sectional view through a leg assembly; 
     FIG. 4 is a fragmentary, perspective, exploded view of the leg assembly illustrated in FIG. 3; 
     FIG. 5 is a top plan view of a ramp section; 
     FIG. 6 is a fragmentary, exploded, perspective view of one corner of the ramp section; 
     FIG. 7 is a fragmentary perspective assembled view of the corner of the ramp section; 
     FIG. 8 is a fragmentary perspective view of the ramp corner with the support bracket removed; 
     FIG. 9 is a sectional view taken along plane IX--IX in FIG. 7; 
     FIG. 10 is a top plan view of the connector unit; and 
     FIG. 11 is a fragmentary perspective view of one corner of the connector unit. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A modular wheelchair ramp constructed in accordance with a preferred aspect of the invention is illustrated in FIGS. 1 and 2 and generally designated 10. Basically, the ramp includes a supporting frame assembly 12 and a plurality of ramp sections 14 removably supported thereon. The frame 12 in turn includes a plurality of leg assemblies 16 arranged to define a ramp path. Each leg assembly 16 includes a pair of upright members or leg 18 and a crossbar 20 slidably mounted thereon. The ramp sections 14 each include brackets 22 which fit over the crossbar 20 to support the ramp sections on the frame. A plurality of handrail segments 23 are mounted between legs 18 of adjacent leg assemblies 16 to provide a continuous handrail. 
     As illustrated in FIG. 2, the ramp 10 is typically installed to provide access to a residential dwelling or other building 25. The ramp is erected in modular fashion beginning at the high end 32 by erecting two leg assemblies and mounting a ramp 14 thereon. Thereafter, a leg assembly and additional ramp section are sequentially installed to provide the ramp path. The height of each crossbar 20 on each leg assembly 16 is adjusted to provide a generally uniform slope throughout the length of the ramp. The ramp includes a low end 30, a high end 32, and a turn or transition point 34 midway therealong. The low end 30 leads off a concrete walk 36; and the high end 32 exits onto a porch 38. By using the ramp, one may easily bypass the stairs 40 leading from the walk 36 to the porch 38. 
     The construction of the support assemblies 16 is illustrated in FIGS. 3 and 4. Generally speaking, the leg assembly 16 includes a pair of vertical upright members or legs 18 (only oe of which is shown in FIGS. 3 and 4), a horizontal support member or crossbar 20 extending therebetween, and a handrail 40. All of the components of the support assemblies 16 are fabricated substantially exclusively of PVC plumbing components. 
     The leg 18 (FIGS. 3 and 4) includes a body 42, a foot 44, and a cap 46. In the preferred embodiment, the leg body 42 is 11/2-inch PVC pipe. A plurality of apertures 48 each having a diameter of 5/16 inch are drilled on 2-inch centers along the height of the leg body 42 to provide an interlock mechanism as will be described. The foot 44 is a PVC bell reducer of the size 3 inch to 11/2 inch and is secured to the lower end of the leg body 42 using a suitable conventional plumbing adhesive. The cap 46 is removably mounted on the upper end of the leg body 42 to provide a neatly finished aesthetic appearance and to prevent articles from being deposited or otherwise accumulating within the leg 18. 
     The crossbar 20 (FIGS. 3 and 4) includes a crossbar body 50 and a T-slide 52. In the preferred embodiment, the crossbar body 50 is a 2-inch PVC pipe. The T-slide 52 in turn includes a 2-inch PVC slip T 54 and a pair of reducer sleeves 56 (with the stops removed) mounted therein. The slip T 54 defines a cylindrical throughbore 58 having an upper end 60 and a lower end 62. One reducer sleeve 56 is fixedly secured within each of the upper and lower ends 60 and 62 to reduce the diameter of the T-slide 52 in these areas from 2 inches to 11/2 inches. The slip T 54 further includes an annular collar 64 extending perpendicularly from the throughbore 58. The crossbar body 50 is fixedly secured within the collar 64 using a suitable conventional plumbing adhesive. 
     The T-slide 52 is freely slidable along the leg body 42 so that the crossbar 20 can be elevated or lowered to any desired height. The T-slide 52 includes a pair of apertures 66 (see FIG. 4) which can be aligned with the apertures 48 in the leg body 42. Therefore, the slip T 52 and leg 18 can be interlocked at any desired height by inserting 1/4-inch bolts (not shown) or other elongated fasteners through the aligned apertures 48 and 66. 
     The handrail segments 23 (FIGS. 1-4) are mounted on the vertical legs 18 in a manner similar to that of the crossbars 20. The resultant handrail is preferably 30 to 34 inches above the ramp surface. Specifically, the handrail segments 23 each includes a T-slide 52&#39; identical to that described above. However, a stub pipe 70 is secured within the annular collar 64&#39; instead of the crossbar body. Also supported on the stub pipe 70 is the annular collar 64&#34; of yet another slip T 54&#34;. The throughbore 58&#34; of the second slip T 54&#34; is oriented generally perpendicularly to the throughbore 58&#39; of the T-slide 52&#39;. The handrail body 76 is supported within the throughbore 74, so that the handrail body 76 is oriented generally perpendicularly to the crossbar bodies 50. 
     The construction of the ramp sections 14 is illustrated in FIGS. 5-9. Each section includes a frame 80, a ramp surface 82, and four support brackets 84. The frame 80 includes a pair of side rails or stringers 86 and three crossbraces 88 extending therebetween. The crossbraces 88 are secured at both of their opposite ends to the stringers 86 using angle brackets 90 and screws (not shown) in conventional fashion. The stringers 86 and crossbraces 88 are both fabricated of Wolmanized (trademark) two-by-fours. The inner upper corner when viewed in cross section of the stringers 86 is routed to form a ledge 91 and a lip 92 extending upwardly from one side thereof a height of 11/2 inches. As seen in FIGS. 8 and 9, the upper edges of the crossbraces 88 are level with the ledge 91 to define a support plane for the ramp surface 82. The outer side of the stringer 86 is also removed adjacent the end of both stringers to form a recessed face 94 to receive the support bracket 84 as will be described. 
     The ramp surface 82 is generally planar and in the preferred embodiment is Wolmanized (trademark) 3/4-inch plywood four-feet-by-four-feet square. The ramp surface 82 is secured to the frame 80 using nails or other conventional fasteners. At its lateral edges 81, the ramp surface 82 fits within the lips 92 and rests on the ledge 91. Since lip 92 extends 11/2 inches up from ledge 91, the lip extends approximately 3/4-inch above the the ramp body 82 to reduce the possibility that an object, such as a wheelchair wheel, will fall off the edge of the ramp. At its end edges 83, the ramp surface 82 extends beyond the crossbrace 88 a distance of 11/2 inches to accommodate the crossbar 20 on the leg assembly 16. 
     The support bracket 84 (FIGS. 5-7 and 9) is fabricated of steel plate approximately 1/4 inch thick. The plate 84 is generally rectangular and includes a body portion 100 and a generally L-shaped leg 102 which together define a downwardly opening cut-out 104. A plurality of 7/16-inch apertures or holes 106 extend through the plate body 100 enabling 3/8-inch bolts 108 to be inserted therethrough and the stringer 86 to support the plate on the frame 20. When the plate 84 is secured against the recessed face 94, the exposed surface of the plate is generally coplanar with the outer surface of the stringer 86; and the centerline of the arch 104 is aligned with the end edge 83 of the ramp surface 84. The downwardly opening cut-out 104 is generally arch-shaped having linear sides and a semicircular upper edge. The dimameter of the semicircular edge is slightly larger than the outer diameter of the flange 64 on the slide fitting 52 to fit closely thereabout. 
     The connector section 110 (FIGS. 1-2 and 10-11) interconnects two ramp sections 14 at the turn 34 (FIG. 2) of the ramp path. The connector unit 110 includes a frame 112 and a ramp surface 114 supported thereon. The frame 112 includes a pair of stringers 116 interconnected by preferably three crossbraces 118. The ramp body 114 is secured on top of the frame 112 using nails or other conventional fasteners. The dimensions of the ramp body 114 are two-feet-by-four feet. Each of the four corners 120 of the connector unit are notched to interfit with the legs 18 of the adjacent support stands 16. A plurality of throughbores or bolt holes 122 are provided in the stringers 116 enabling bolts (not shown) to pass through the stringers 122 and the adjacent stringers 86 of the ramp sections 14 to secure the support unit in place. The connecting unit 110 does not hook onto the frame assembly 12, but is bolted directly to the adjacent ramp sections. 
     ASSEMBLY 
     The modular ramp 10 is sold or otherwise distributed in kit form. Depending upon the rise and dimensional constraints, the manfuacturer or distributor will provide the customer with a kit including the components required to erect an appropriate ramp. Although a U-shaped ramp is illustrated in FIGS. 1 and 2, it is envisioned that other ramp configurations can be assembled using the described components. 
     Typically beginning at the highest end 32 of the ramp 10, the installer will erect the first two leg or support assemblies 16. If the ramp is installed on a hard surface such as concrete, the feet 44 rest on top of the concrete. If the ramp is installed on soil or other soft surface, the feet 44 are forced into the ground to the full extent of their height to provide an appropriate nonshiftable base for the ramp. The leg assemblies 16 are installed on four-foot centers to receive the four-foot-by-four-foot ramp sections 14. The crossbars 20 of the first two leg assemblies are adjusted to be 3/4 inch below the height of the porch 38. Consequently, the ramp surface 84 of the first ramp section 14 will be level with the porch. After the crossbars have been adjusted and locked or bolted in position, the ramp section 14 is intalled by hooking the pairs of brackets 84 on either end of the ramp section over the appropriate crossbar 20. 
     The installer thereafter sequentially erects a leg assembly and installs a ramp section 14. Present government regulations call for a rise of no greater than 1:12. Therefore, the opposite ends of each ramp section 14 can be no greater than 4 inches different in height. Each crossbar 20 is appropriately adjusted and bolted in position; and each ramp section 14 is installed after the crossbar has been so adjusted. The end edges 83 of adjacent ramp sections 14 abut one another over the associated crossbar 20. 
     At the transition point or curve 34 (FIG. 2), the transition unit 110 is bolted between the two adjacent ramp sections 14. 
     The last section 14 at the lower end 30 is installed to meet and be level with the sidewalk 36. As illustrated in FIG. 1, this lowermost section can be recessed into the ground. Alternatively, the stringers 86 on this section can be cut diagonally to lay directly on the ground. If the stringers are so cut, the brackets from the lowermost end are eliminated. 
     After all ramp sections 14 have been installed as described, the handrail sections 23 are installed on the upper ends of each leg 18. The hand rail sections are installed on each side of the ramp path. The slide fitting 52 on either end of each handrail section 21 is adjusted to be a uniform height, preferably 30 to 34 inches, above the associated ramp section 14; and bolts are used to secure the handrail slide fittings 52&#39; in position. Preferably, an intermediate guardrail (not illustrated) is installed between the handrail and the ramp surface for safety and curbing. If so included, the construction of the guardrail is preferably identical to that of the handrail. After all handrail sections 23 are installed, the top caps 46 are placed on the upper end of each leg 18. Preferably, the top caps 46 are not adhered in position to facilitate subsequent disassembly of the ramp 10. 
     The present ramp is also suitable for use in other installations, such as marinas, wherever people are required or desire to transition between areas of different heights or levels. 
     The present invention provides a ramp 10 which is easily assembled without any resultant waste. The modular components facilitate manufacture and also ease the assembly of the appropriate kit for a particular installation. Although the construction is relatively simple, the resultant ramp 10 is extremely strong and serviceable. Further, the ramp 10 can be readily disassembled when no longer needed and reinstalled at another dwelling or recombined with other ramp components to produce a ramp kit for a different installation. 
     The above description is that of a preferred embodiment of the invention. Various alterations and changes may be made without departing from the spirit and broader aspects of the invention as set forth in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents.

Summary:
The specification discloses a modular and reusable wheelchair ramp capable of ready assembly and disassembly while providing a strong and safe construction. The ramp includes a plurality of leg assemblies fabricated of PVC plumbing components and a plurality of ramp sections each extending between and mounted on a pair of adjacent leg assemblies. Each leg assembly includes a pair of legs and an interconnecting crossbar slidably received thereon for ready height adjustability. The ramp sections are hooked over the crossbars. In a preferred embodiment, handrails also fabricated of PVC plumbing components are also slidably mounted on the legs.