Patent Publication Number: US-6666621-B1

Title: Temporary trench cover and rail

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a temporary trench cover for use during construction and a rail member used in forming the trench cover. 
     During construction of a building, or in retrofitting an existing building, it is often necessary to cut a trench through a concrete slab, and into the underlayment, for placement of pipes or electrical wiring. Such trenches must be accessible for the period of time required to complete the laying of the pipe or wiring. For safety reasons, temporary covers must be placed over the trench opening during the period of time they are not being accessed so that workers or the public at the construction site will not inadvertently step into the trench, thereby causing them to fall and become injured. 
     It is typical at such sites to temporarily cover a trench with a steel plate. However, such plates are expensive, are heavy and difficult to handle, and have edges extending above floor level which can cause a person to trip and fall. p It has also been suggested to anchor 2″ by 4″ wooden blocks to the entire inside upper edge of a trench and nail or screw one inch thick plywood strips to the tops of the blocks. Although the blocks can be positioned so that the upper surface of the plywood is level with the floor surface to eliminate tripping, such a system is very time consuming to construct, hard to remove, and access to the trench is costly and narrows the width of the trench by about three inches. In addition, since the blocks are typically anchored about four feet apart, the system is not very strong. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a temporary trench cover for relatively narrow trenches, i.e., up to about 48 inches in width, that reduces or eliminates the problems encountered with many prior temporary trench covers. 
     The temporary trench cover of the present invention includes a pair of longitudinally extending rails, the rails being spaced apart and substantially parallel to each other. Each rail includes a web extending between an upper flange and a lower lip. The flange, web and lip form a C-shaped channel. The C-shaped channels of the cover&#39;s pair of rails face each other. A substantially flat cover member having longitudinally extending edges is positioned within the C-shaped channels of the rails and is attached to the rails. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an end elevation view of the temporary trench cover of the present invention; 
     FIG. 2 is an end elevation view of the temporary trench cover of the present invention shown covering a trench opening; 
     FIG. 3 is a front perspective view of the rail member of the temporary trench cover of the present invention; 
     FIG. 4 is a front elevation view of the rail member of the temporary trench cover of the present invention; and 
     FIG. 5 is an end elevation view of the rail member of the temporary trench cover of the present invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The temporary trench cover  10  includes a pair of identical longitudinally extending rail members  20  and flat cover member  30 . Rail members  20  can be made in any length or various lengths; it is preferred to provide rail members  20  in lengths of eight feet each. 
     Each rail member  20  includes a web  22 , an upper flange  24  and, an outwardly projecting lower lip  26 . The planes of flange  24  and lip  26  are substantially perpendicular to the plane of web  22 , and substantially parallel to each other. Web  22  and upper flange  24  form a T-shaped member. Web  22  and lip  26  form an L-shaped member (as seen in FIG.  3 ). Web  22 , flange  24  and lip  26  are integral, and rail member  20  is preferably formed by the continuous extrusion of metal or plastic. 
     Flange  24  extends outwardly from web  22  a substantially equal distance in both directions, the distance being substantially equal to the distance lip  26  extends outwardly from web  22 . The upper surface of flange  24  is arcuate in shape. The bottom surface of flange  24  is substantially flat, and that portion of flange  24  extending outwardly over lip  26  together with web  22  and lip  26  form a C-shaped channel  28 . The height of C-shaped channel  28  is such as to accommodate the thickness of cover member  30 . The thickness of cover member  30  is preferably between about ¾ inch and about one inch. 
     Although not intended to be limiting, a preferred width for flange  24  is about two inches, and a preferred thickness for web  22  and lip  26  is about {fraction (3/16)} inch. 
     Web  22  has a plurality of fastener receiving holes  29  extending therethrough. 
     The temporary trench cover  10  includes a pair of substantially parallel rails  20  whose C-shaped channels  28  face each other, as seen in FIGS. 1 and 2. 
     The longitudinally extending edges of a cover member  30  are inserted into the C-shaped channels  28  and fastened thereto by fastening members  32  passing through holes  29  in rails  20 . Where cover member  30  is plywood or wood, fastening members  32  may, for example, be nails or screws. Although fastening members  32  are shown in FIG. 1 as having a head extending outwardly from the outer surface of web  22 , holes  29  can be configured so that the heads would be completely recessed within the outer surface of web  22 . 
     The width of cover member  30  is selected so that, together with the thickness of webs  22 , the temporary trench cover  10  will extend across the width of a trench to be covered. Temporary trench cover  10  is intended for use primarily with relatively narrow trenches, i.e., having a width up to about 48 inches. 
     Cover member  30  is preferably made of plywood because of its relatively light weight and good strength characteristics. The thickness of the plywood used for cover member  30  is preferably about ¾ inch for relatively narrow trenches (up to about 18 inches in width) or about 1 inch for wider trenches (from about 18 inches up to about 48 inches). 
     FIG. 2 shows the temporary trench cover  10  covering a trench  40  cut through a concrete slab  50  and its underlayment. The outer surfaces of webs  22  abut against the edges  52  of the slab  50  with the outer bottom surfaces of upper flanges  22  in abutment with the upper surface of the slab  50  adjacent edges  52  thereof. As can be seen, temporary trench cover  10  merely rests unattached within trench  40 , and can be easily and quickly inserted therein and removed therefrom. 
     The top surface of upper flange  22  has an arcuate shape, as shown, so that persons passing thereover are not presented with an edge that can cause tripping. The outer longitudinal edges of flange  22  can be very thin, preferably about {fraction (1/16)} inch, with the middle of flange  22  (i.e., its crown) having a thickness of about {fraction (3/16)} inch (the same thickness as web  22  and lip  26 ). 
     A plurality of trench covers  10  would be placed end to end along the length of a trench  40 . The rails  20  and cover  30  of an end trench cover  10  can be easily cut to the length required to fit the length of the end of a trench  40 . 
     It will be obvious to those having skill in the art that many changes may be made to the details of the above-described embodiments of this invention without departing from the underlying principles thereof. The scope of the present invention should, therefore, be determined only by the following claims.