This application claims the benefit under 35 USC 119(e) of Provisional application Ser. No. 60/336,200 filed Oct. 23, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to bridges and more particularly to a bridge construction for use in road building in wetlands and stream crossings where ecological importance recognizes that natural stream bottoms are essential for preservation of fish and other aquatic wildlife. 
     Bridges provided heretofore for the purpose are much too complex and costly for use by farmers and the like to provide for the crossing of vehicles and pedestrians over small streams and wetlands. 
     Typical of such prior bridge constructions are those disclosed in U.S. Pat. Nos. 3,981,038 and 5,471,694. 
     SUMMARY OF THE INVENTION 
     This invention provides a short span bridge construction for small streams and the like that is formed of standardized deck sections and a supporting assembly of a plurality of interconnected standardized pier blocks. 
     It is the principal objective of this invention to provide a bridge construction that overcomes the disadvantages and limitations of prior bridge constructions. 
     Another objective of this invention is the provision of a bridge construction of the class described which is capable of assembly with conventional light cranes or excavation type equipment. 
     Still another objective of this invention is to provide a bridge construction of the class described in which the deck plates are provided with means for securing their longitudinal abutting edges together against relative vertical displacement. 
     A further object of this invention is the provision of a bridge construction of the class described which includes pier blocks capable of being secured together in an outwardly angled arrangement for diverting upstream water toward the center of the stream. 
     A still further objective of this invention is the provision of a bridge construction of the class described in which the deck plates and pier blocks are constructed of reinforced concrete in standardized sizes providing for convenient and economical manufacture and inventory control. 
     The foregoing and other objects and advantages of this invention will appear from the following detailed description, taken in connection with the accompanying drawings of preferred embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary plan view of a bridge construction embodying the features of this invention. 
     FIG. 2 is a fragmentary foreshortened longitudinal section taken on the line  2 — 2  in FIG.  1 . 
     FIG. 3 is a plan view of the top end of a pier block. 
     FIG. 4 is a vertical sectional view of the pier block taken on the line  4 — 4  in FIG.  3 . 
     FIG. 5 is an exploded plan view of the top and adjacent one of stacked pier blocks shown in FIG.  1 . 
     FIG. 6 is a plan view of a further pier block configuration. 
     FIG. 7 is a plan view of an alternative pier block configuration which adds to FIG. 6 the offset end segments for increased stability. 
     FIG. 8 is a fragmentary sectional view taken on the line  8 — 8  in FIG.  1 . 
     FIG. 9 is a fragmentary sectional view showing the function of the arcuate configuration of connectors between sloping deck plates on underlying vertical pier blocks. 
     FIG. 10 is a fragmentary vertical elevation of an assembly of pier blocks for a tall pier block configuration. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates a bridge embodying the novel features of this invention spanning a stream S below and confronting a roadway R to afford the crossing of vehicles and pedestrians. The bridge is formed of a plurality of modular components including a plurality of pier blocks  10  positioned at opposite sides of the stream and disposed in end-to-end abutment. In the embodiment illustrated in FIGS. 1,  2  and  5  the pier blocks have rounded ends arranged in abutment to form a unitary elongated structure predetermined to provide a bridge width suitable for the intended purpose. 
     FIG. 2 illustrates the bridge construction of FIG. 1 requiring stacked end piers because the stream S is at a lower level relative to the roadway R. In the preferred embodiment illustrated, the pier blocks  10  previously mentioned are stacked vertically in two or more rows to accommodate the desired height. For this purpose each block is provided at its bottom side with spaced sockets  12  (FIGS. 2 and 4) configured to receive the correspondingly spaced upward projections  14  on the top sides of overlying pier blocks. As shown in FIG. 5, the pier blocks of an overlying row are arranged to span the juncture between adjacent blocks of the underlying row. This arrangement serves to secure together all of the blocks in all of the rows, against longitudinal displacement. 
     FIGS. 1 and 5 illustrate the use of outwardly angled wing blocks  10 ′ at at least the upstream end of the bottom pier block rows which are immersed in the stream, for diverting rushing flood waters toward the center of the stream and thus prevent damage to the installation. As illustrated, two end blocks  10 ″ at the opposite ends of the next upper row of pier blocks  10  span the inner portions of end blocks  10 ′ and adjacent outer end portions of the next adjacent confronting pier blocks to secure the outward angle. Openings  16  centrally through the projections  14  and sockets  12  are in alignment when pier blocks are stacked vertically, allowing a length of threaded rod  18  (FIG. 2) to be inserted through the stacked blocks. An enlarged portion  16 ′ of the vertical openings  16  at the top of each pier block receives a washer  20  and threaded nut  22  to secure the rod  18  vertically. After concrete grout  24  is filled into the openings  16 , the rod is pushed into place, the washer  20  and nut  22  installed, and grout is filled into the opening  16 ′ to secure the rod. Compressible, flexible rod material  26  is interposed between the pier blocks and deck plates to prevent escape of grout. The stacked blocks thus are secured against lateral displacement. 
     If the wing blocks are not needed, the blocks are disposed on a straight line, as illustrated by the top row of blocks in FIG.  5 . 
     FIG. 6 illustrates an alternative configuration of a single, long pier block  10   a  which differs from the shorter pier blocks  10  in FIG.  5 . The long block is dimensioned to extend the full width of a bridge to be erected. It may range in length between 10 and 25 feet (3-7.5 meters), although other lengths may be used as desired. It is typically about 2.5 feet (0.75 meter) wide and about 15 inches (38 cm) high. Again, other dimensions may be selected, as desired. This single pier block is desirable for use in installations that do not need the assembly of the shorter pier blocks  10  of FIG. 5, whereby to minimize installation time and cost. The interengaging sockets  12 , projections  14  and openings  16  are provided, as are weep holes  15  through the width of the block to relieve water pressure. 
     FIG. 7 illustrates a single, long pier block  10   b  which is provided with end returns  10   b ′ extending laterally outward from the intermediate section  10   b  to afford greater lateral stability in certain soil and other base conditions. The previously described sockets  12 , projections  14 , openings  16  and weep holes  15  also are provided. 
     As previously mentioned the top longitudinal side of each pier block  10  is provided with a plurality of spaced apart upwardly rounded projections  14  configured for reception in correspondingly spaced sockets  12  formed in the underside of each pier block. Similarly spaced sockets  28  are provided in the bottom surfaces of a plurality of deck plates  30  adjacent each end thereof. The longitudinal spacing between the end sockets  28  is configured to conform to the spacing between projections  14  on the rows of pier blocks  10  on the opposite sides of the stream to be spanned. 
     The projections  14  are spaced apart on each pier block so that when arranged together to form an elongated row the spacing between adjacent projections on adjacent blocks is the same as the spacing of the projections on each block, as best illustrated in FIG.  5 . Thus, the spacing between the sockets  28  at each end of a deck plate  30  serves to lock the pier blocks together against longitudinal placement. The spacing between the sockets  28  at each end of a deck plate  30  also allows adjacent deck plates to be secured together against lateral displacement, as illustrated in FIG.  1 . 
     The deck plates  30  match the length and thickness of the intermediate deck plates and the configuration of the sockets  28  in the underside matches the sockets in the intermediate deck plates. The curbing  32  preferably is about 6 inches (15 cm) high and 6 inches wide. 
     The longitudinal sides of adjacent deck plates  30  are secured by the connector device best shown in FIG.  8 . The side edge  34  of each adjacent plate is contoured angularly so that the space between adjacent plates tapers from the upper surface of the plate downward to smaller dimension. Additionally, the tapered side is interrupted intermediate its top and bottom ends with an indentation  36  configured to align with the indentation on the edge of the adjacent plate to form a lock. 
     When the adjacent plates are arranged on the underlying supporting pier blocks, a length of resilient packing  38  is forced downward in the tapered space until it is located at the bottom of said space. Concrete grout material  40  then is flowed into the tapered space, including the lock  36 , the packing  38  preventing escape of grout from the space. When the grout is cured and hardened the adjacent deck plates are bonded together permanently and the plates are secured against relative vertical displacement by virtue of the lock  36 . Transverse rods  30 ′ preferably are extended through aligned openings horizontally through the width of the deck plates  30 , and end nuts are drawn against the opposite sides of the deck plate assembly to clamp them together against lateral separation. 
     Manipulation of the pier blocks for installation is facilitated by lifting hooks  42  (FIGS. 3 and 4) integrated into the blocks during formation and curing of the concrete. A lifting crane or other hoisting apparatus needs only a grappling hook for engaging the lifting hooks. Analogous hooks (not shown) are provided on the ends of the deck plates  30  to facilitate lifting and placing them on the pier blocks. The rounded projections  14  on the pier blocks and corresponding sockets  28  in the underside of the deck plates  30  enables proper angular mounting of the deck plates to correspond with the slope of the roadway relative to horizontal, as illustrated in FIG.  9 . 
     It is to be noted from FIG. 9 that the openings  16  in the deck plates  30  are larger than the threaded rod  18 , to allow angular adjustment of the deck plates relative to the vertically extended pier blocks. This accommodates installation of deck plates to conform to the slope of roadway R connected by the bridge. Compressible, flexible rod material  44  is interposed between the pier block and deck plate to prevent escape of grout  24 . 
     In the preferred construction of the modular components of the bridge described hereinbefore, the pier blocks  10  are preformed of concrete poured into molds. If desired, reinforcing rebar may be embedded in the concrete. The size and shape of the pier blocks may be varied, as desired. A preferred configuration of pier block is 5 feet (1.5 meters) long, 2.5 feet (0.75 meter) high and 2.5 feet (0.75 meter) thick. The rounded projections  14  at the top end are about 2.5 inches (6.35 cm) tall and about 18 inches (43.2 cm) in diameter at the base. The sockets  12  in the bottom end are configured to seat the top projections of an underlying row. 
     The deck plates  30  also preferably are of precast concrete, with embedded reinforcing rebar. The width of the deck plate preferably is 2.5 or 5 feet (0.75 or 1.5 meters) to overlie the 5 feet dimension of the pier block  10 . The plates preferably are 8-12 inches (15 cm) thick. Sockets  28  in the underside of the deck plates adjacent the opposite ends are spaced apart laterally to match the spacing of the projection  14  in the top ends of the upper row of pier blocks. The length of the deck plate is variable to accommodate the bridge length required to span a specific stream or other body of water. This typically ranges between 9 and 25 feet (4.5-8 meters), although other lengths may be accommodated, as desired. 
     FIG. 10 illustrates a bridge configuration for crossing a stream S located a substantial depth below a roadway R. For this purpose the pier blocks  46  and  48  are provided in single and double lengths, respectively, to accommodate assembly into progressively increasing lengths downwardly from a roadway level to the level of a stream S. The uppermost pier blocks  46  and deck plates  30  are secured together by a length of rebar  50  extended through the central openings  16  in the blocks and plates, and grout material  52  is filled into the openings  16  and  16 ′ to secure the blocks and plates together against displacement. Compressible rod material  54  seals the bottom of opening  16  and the space between the deck plates and pier blocks. 
     From the foregoing it will be apparent that this invention provides for the economical construction of a bridge with relatively small lifting equipment for spanning relatively small streams and other waters, by utilizing standardized sizes of pier blocks and deck plates with corresponding interengaging connector members for constructing bridges of different lengths and widths and different vertical distances between a waterway and a roadway. The standardization of pier blocks and deck plates affords economical manufacture and simplified inventorying of sizes for rapid selection according to the selected stream location. 
     It will be apparent to those skilled in the art that various changes may be made in the size, shape, type, number and arrangement of parts described hereinbefore, to accommodate specific requirements of length, height, width, loading and other parameters. Preferably, they are sized to provide an inventory of standardized components and to accommodate use of light cranes or excavated type equipment in transporting and manipulating them at a installation site. These and other modifications may be made, as desired, without departing from the spirit of this invention and the scope of the appended claims.
This application discloses a novel bridge construction for use in affording vehicle and pedestrian traffic over small streams and wetlands. The construction utilizes standardized sizes of pier blocks for supporting standardized deck plates, with interengaging anchor projections and sockets one on the upper ends of the pier blocks and the other on the undersides of the deck plates. Identical sockets also are provided on the bottom ends of the pier blocks for engaging the projections on underlying pier blocks, affording vertical stacking of pier blocks to accommodate varying vertical distances between a stream and an elevated roadway. A V-shaped groove formed by the tapered longitudinal edges of adjacent deck plates, together with a registering outward indentation communicating with the groove, is adapted for filling with a concrete grout, for securing the deck plates against vertical displacement.