Abstract:
The present invention is directed to a precast girder that is used as the outer-most lateral girder in a bridge superstructure. In one embodiment, the girder is comprised of a first flange, a second flange that is separated from the first flange, and a web that connects the first flange to the second flange so that the resulting combination of the first flange, second flange, and web generally has an I-beam cross-section. The girder further includes an edge portion that is connected to the second flange and extends away from the first and second flanges.

Description:
FIELD OF THE INVENTION 
     The present invention is directed to an apparatus for use in constructing a bridge and a method for constructing a bridge. 
     BACKGROUND OF THE INVENTION 
     The main elements of the type of bridge to which the invention is directed are: (a) a substructure; and (b) a superstructure. 
     A substructure is comprised of (1) foundations and (2) piers. The foundations are the components of the substructure that engage or interact with the earth to support the bridge structure. A foundation can be constructed of one or more piles, one or more concrete drilled shafts, one or more concrete mats, and combinations thereof. Presently, piles include precast concrete piles and steel piles. The piers are the components of the substructure that transfer the bridge structural loads to the foundations. A pier can be constructed of columns, struts, pile caps, pier caps, and combinations thereof. Presently, columns include cast in place columns, precast concrete columns, and steel columns. 
     A superstructure carries the traffic load (vehicular, rail, and/or pedestrian) on the bridge. A superstructure can be constructed using girders that each typically span the distance between two adjacent piers. Presently, girders include precast concrete girders, cast in place girders, precast concrete box girders, segmental box girders, steel girders, and steel box girders. Some superstructures use two or more different types of girders. 
     Presently, there are several methods of constructing a bridge comprised of a substructure and a superstructure (hereinafter referred to as a “bridge”) in situations in which there is limited access from the ground. Characteristic of each method is the use of one or more conventional cranes that are each capable of rotating a boom about horizontal and vertical axes to either move an element of bridge into place or manipulate a tool that is used in constructing the bridge. One method employs a crane that is positioned on top of and near the end of the existing superstructure to position a pile driver and a pile beyond the end of the superstructure so that the pile can be driven into the earth to form the next foundation. Typically, a second crane is used to provide piles to the pile driver associated with the first crane, construct the pier that engages the pile or piles of the foundation established by the first crane, and construct the, either alone or in combination with the first crane, the superstructure. A drawback associated with this method is that the piers must be spaced relatively close together due to the construction loads imposed upon the bridge by the crane, the pile driver, and the pile. 
     Another method for constructing a bridge when the bridge is being built over a watercourse or wetland involves using a temporary structure that extends outside the footprint of the resulting bridge to support cranes and the like that are used in constructing the bridge and, in particular, the substructure of the bridge. In many case, the temporary support structure adversely affects the portions of the watercourse or wetland that are outside the footprint of the bridge. Typically, the temporary support structure supports a first crane to which a pile driver has been attached, a second crane for loading a pile into the pile driver associated with the first crane, a third crane for constructing a pier on each of the foundations established by the first and second cranes, and a fourth crane for putting the girders in place between adjacent piers. In some cases, the third and/or fourth crane are replaced with a moveable gantry or truss that spans the distance between at least two adjacent piers and is located above and substantially parallel to the superstructure to construct the piers and establish girders between adjacent piers. 
     Also associated with the construction of bridges is the attachment of L-shaped form to the outer-most lateral girders and the subsequent pouring of concrete into the forms to establish an L-shaped concrete member along the lateral edges of the superstructure. These L-shaped members typically facilitate the establishment of barriers along the lateral edges of the superstructure and serve to contain the concrete or other fluid material that is used to establish the superstructure deck. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an apparatus and method for use in constructing a bridge that substantially avoids the need for a temporary support structure for cranes and other machinery and/or the need to use conventional cranes to manipulate the main elements of the substructure and superstructure that are used to form the bridge. 
     In one embodiment, the apparatus is comprised of: (a) a truss structure that extends from a first end to a second end, (b) a support structure that, in operation, supports the truss structure such that a portion of the truss structure is above and substantially parallel to the superstructure or planned location of a portion of the superstructure, (c) a trolley that, in operation, is supported by the truss structure, capable of hoisting an object associated with the building the bridge, and movable between the ends of the truss structure, (d) a lead assembly that, in operation, is operatively attached to the truss structure and comprises a lead, a pivot joint for pivotally connecting the lead to the truss structure, and an actuating system for causing the lead to pivot to a desired rotation position. When the lead is in a predefined position, the lead is capable of receiving an object from the trolley. For example, the lead can receive a pile from the trolley and rotate the pile to place the pile in the desired rotational orientation for establishing a pier. 
     Another embodiment of the apparatus comprises a lead assembly that comprises a lead, a pivot joint for pivotally connecting the lead to the truss structure, an actuator system for causing the lead to pivot to a desired rotational position, and a tool that is operatively attached to the lead. In one embodiment, the tool is a hammer that is used to drive a pile that is held by the lead into the ground. In another embodiment, the tool is a drill that is used in drilling a hole for accepting a portion of a pile or in drilling a hole for a concrete drilled shaft, i.e., a concrete pile that is formed by excavating a hole within a casing that has been hammered or otherwise driven into the ground, filling the hole with concrete, and subsequently removing the casing. Yet a further embodiment comprises a conveyor system that is used to remove the earth that the drill excavates from a hole that is being established in the ground. 
     Yet a further embodiment of the apparatus comprises a lead, a two-axis pivot joint for connect the lead to the truss structure and allowing the lead to be rotated about a first axis and a second axis, an actuator system for causing the lead to rotate about the first and second axes to desired rotational positions relative to the first and second axes. The ability to rotate the lead about two axes allows foundations that have battered piles (i.e., piles that are oriented other than plumb) to be constructed, as well as foundations that have plumb piles, and to compensate for various misalignments or variations in the orientation of the truss structure. 
     One embodiment of the method of constructing a bridge comprises providing a bridge building apparatus that comprises (a) a truss structure that extends from a first end to a second end, (b) a trolley that is operatively attached to the truss structure, capable of hoisting an object, and movable between the first and second ends of the truss structure, (c) a lead that is operatively attached to the truss structure and capable of being rotated between a first position at which the lead is capable of receiving an object from the trolley and a second position. The method further comprises positioning the bridge building apparatus so that a portion of the truss structure is above and substantially parallel to a portion of the superstructure or planned location of a portion of the superstructure. The method further comprises placing the lead in the first position, using the trolley to move a substructure related element so that the substructure related element is received by the lead, and rotating the lead so that lead and the substructure related element to an orientation suitable for positioning the substructure related element to aid in the construction of the bridge. 
     In an embodiment of the method in which the substructure related element is a pile, the method further comprises lowering the pile until the pile engages the ground and then hammering the pile into the ground. Similarly, in an embodiment in which the substructure related element is a casing for use in casting a concrete shaft, the method further comprises lowering the casing until the casing engages the ground and then hammering the casing into the ground. 
     An embodiment of the method in which the substructure related element is a pier column further comprises lowering the pier column until the pier column engages a pre-established foundation or pier structure. Similarly, an embodiment of the method in which the substructure related element is column form or casing for use in casting a pier column, the method further comprises lower the casing until the form or casing engages a pre-established foundation or pier structure. 
     Yet another embodiment of the method comprises using the trolley to position a girder between two adjacent piers. 
     A further embodiment of the method comprises: (a) providing a bridge building apparatus that include a truss structure, trolley, and lead that can be rotated to a position at which the lead can receive a substructure related element, (b) positioning the truss structure above and substantially parallel to a portion of the superstructure or a planned location for a portion of the superstructure, (c) positioning, if needed, the truss structure so that the lead can be used to put in place a substructure element, (d) using the trolley and the lead to position a substructure element, (e) positioning, if needed, the truss structure so that the trolley can be used without the lead to position a substructure element or a superstructure element, (f) using the trolley to position a substructure element or superstructure element. 
     The present invention is also directed to a pre-cast edge girder, i.e. a girder that is used is the outer-most lateral girder in a bridge. The pre-cast edge girder is comprised of a laterally extending portion and an vertical extending portion that is operatively connected to the laterally extending portion thereby forming an L-shaped edge girder. Since the L-shaped edge girder is pre-cast, the need to use forms to establish an L-shaped concrete member along the lateral edges of the superstructure is avoided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates the components of an embodiment of an apparatus that is useful in assembling a bridge; 
         FIG. 2  illustrates a first position of the apparatus shown in  FIG. 1  in which the apparatus has been used to establish girders and deck between a first pair of pier structures and a lead pier structure; 
         FIG. 3  illustrates the repositioning of the supports of the apparatus shown in  FIG. 1  so that the truss can be repositioned and then used to erect girders between the lead pier structure and the penultimate pier structure and to establish a new lead pier structure; 
         FIG. 4  illustrates the repositioning of the truss of the apparatus shown in  FIG. 1  so that girders can be erected between the lead pier structure and the penultimate pier structure and a new lead pier structure can be established; 
         FIG. 5  illustrates the delivery of a girder that is to be placed between the lead pier structure and the penultimate pier structure; 
         FIG. 6  illustrates the use of the trolley to erect the girder shown in  FIG. 5  between the lead pier structure and the penultimate pier structure; 
         FIG. 7  illustrates a complete set of girders extending between the lead pier structure and the penultimate pier structure; 
         FIG. 8  illustrates the delivery of a pile for the new lead pier structure; 
         FIG. 9  illustrates the use of the trolley to lower the pile shown in  FIG. 8  onto the pile driver lead and hammer assembly; 
         FIG. 10  illustrates the rotation of the pile driver lead and hammer assembly and the pile held by the assembly; 
         FIG. 11  illustrates the use of the pile driver lead and hammer assembly to lower the pile so that the distal end of the pile engages the earth into which the pile is to be driven; 
         FIG. 12  illustrates the establishment of several piles in the new lead pier structure; 
         FIG. 13  illustrates the use of the trolley to establish a first half of a pier cap form or pre-cast shell on top of several of the piles of the new lead pier structure; 
         FIG. 14  illustrates the use of the trolley to establish a second half of a pier cap form or pre-cast shell on top of several of the piles of the new lead pier structure; 
         FIG. 15  illustrates the use of the trolley to load rebar and concrete into the pier cap form or pre-cast shell established on top of the new lead pier structure; 
         FIG. 16A-C  illustrates an embodiment of a lead assembly that comprises a lead, a hydraulic system that is used to rotate the lead, a hammer that is attached to the lead, and a winch for adjusting the position of the hammer on the lead; 
         FIG. 17  illustrates an embodiment of a pile collar clamp for holding a pile in a fixed position relative to the pile driver lead and hammer assembly during rotation of the pile driver lead and hammer assembly; 
         FIGS. 18A and 18B  illustrate alternative devices for holding a pile or similar structure in place on a lead; 
         FIG. 19  illustrates a portion of a lead assembly that includes a drill for excavating a hole for a pile, concrete drilled shaft, or similar structure; 
         FIG. 20  illustrates a system for the removal of drill tailings produced by the operation of the drill illustrated in  FIG. 19 ; 
         FIG. 21  is a perspective view of the guide box of the system illustrated in  FIG. 20 ; 
         FIG. 22  illustrates a lead with a ground engaging structure that can be extended to contact the ground so as to reduce the force being applied to the end of the truss structure when a heavy object, such as a pile, is being positioned to be driven into the ground; 
         FIG. 23  illustrates an alternative embodiment lead assembly that utilizes a cable, pulley, and winch system to rotate a lead; 
         FIG. 24  illustrates an alternative embodiment of a device that is suitable for rotating a lead in a plane that is transverse to the longitudinal axis of the truss structure; 
         FIG. 25  illustrates a prior-art edge form that is used to establish an L-shaped concrete member along the lateral edge of a bridge superstructure; and 
         FIG. 26  illustrate a pre-cast edge girder that avoids the need to use the prior art edge form shown in  FIG. 18 . 
     
    
    
     DETAILED DESCRIPTION 
     The present invention is directed to an apparatus for use in bridge construction that is comprised of: (a) a truss structure, (b) a support structure for supporting the truss structure such that a portion of the truss structure is above and substantially parallel to a portion or planned portion of a superstructure of a bridge, (c) a trolley structure that is supported by the truss structure and used to move materials used to build the bridge, and (d) a lead assembly that is operatively attached to the truss structure and comprised of a rotatable lead that is capable of receiving a object from the trolley that is useful in constructing the bridge. 
       FIG. 1  illustrates an embodiment of the bridge construction apparatus, hereinafter referred to as apparatus  50 . The apparatus  50  is comprised of: (a) a truss structure  52 ; (b) trolley structure  54 ; (c) a support structure  56 ; and (d) a lead assembly  58 . 
     The truss structure  52  is comprised of a first truss  60 A and a second truss  60 B that is situated substantially parallel to the first truss  60 A. The truss structure  52  extends from a first terminal end  61 A to a second terminal end  61 B. It should be appreciated that other truss structures are feasible. For example, a truss structure that is comprised of a single truss or a truss structure that is comprised of more than two trusses is feasible and may be desirable in certain situations. Further, in contrast to straight character of the truss structure  52 , a truss structure that is curved is feasible and may be desirable if a bridge design follows a curve rather than a straight line. Additionally, a truss structure that is capable of being modified or articulated so that the truss follows a path that comprised of combinations of straight segments, combinations of curved segments, and combinations of straight and curved segments is also feasible. 
     The trolley structure  54  is comprised of four elements: a first main trolley  62 A, a second main trolley  62 B, a first auxiliary winch  64 A, and a second auxiliary winch  64 B. As illustrated, the first and second main trolleys  62 A,  62 B, and first and second auxiliary winches  64 A,  64 B, are capable of operating as a single unit, as separate units, and as intermediate combinations. The ability to operate the elements of the trolley system  64 A as separate elements or as one or more combinations of two or more elements facilitates many of the bridge building operations of the apparatus  50 . Nonetheless, it should be appreciated that a trolley system with a different number of elements is feasible. For instance, a trolley system comprised of a single trolley is feasible. 
     The support structure  56  is comprised of a center support  66 A, rear support  66 B, center auxiliary support  68 A, and rear auxiliary support  68 B. After the initial positioning of the supports at the commencement of the bridge construction, the center and rear supports  66 A,  66 B, and the center and rear auxiliary supports  68 A,  68 B, must be moved from one location to another location to facilitate the forward movement of the truss structure  52  to a new location. At least the center support  66 A and rear support  66 B are moved from one location to another using the trolley system  54 . Typically, the center and rear auxiliary supports  68 A,  6 B are also moved using the trolley system  54 . The center support  66 A and/or the rear support  66 B incorporate motors and related structures that engage the truss structure  52  to move the truss structure  52  relative to the center support  66 A and rear support structure  66 B as is known to those in the art that have employed such trusses to position girders. It should be appreciated, however, that the incorporation of motors into the center and rear supports  66 A,  66 B is not necessary and that movement of the truss structure can be accomplished by other devices, including winches. It should be appreciated that other support systems that are capable of supporting the truss structure such that a portion of the truss structure  52  is above and substantially parallel to a portion or planned portion of the superstructure are feasible. For example, a support system that comprises a motorized, tracked or wheeled, rear support can be fixedly attached to the rear of the truss structure and thereby eliminate the need for the rear auxiliary support. Other support structures could incorporate more supports than the four elements of the support structure  56 . 
       FIG. 2  illustrates the apparatus  50  in a first position with respect to a bridge  80  that is under construction. The bridge  80  is comprised of a superstructure  82  and a substructure  84  that supports the superstructure  82 . The substructure  84  is comprised of foundations that are each comprised of a series of piles and piers that are each comprised of a pier cap that engages the piles of a foundation. The superstructure is comprised of steel girders that are of sufficient length to extend between and engage adjacent pier caps. It should be appreciated that the bridge  80  is exemplary of the type of bridge that the apparatus  50  is capable of being used to construct and that the apparatus is capable of being used to construct bridges with: (a) foundations that are each comprised of a concrete precast pile(s), a concrete drilled shaft(s), a steel structural member(s) or pile(s), a concrete mat(s), any other main foundation element known in the art, and combinations thereof, (b) piers that are each comprised of cast in place column(s), a precast concrete column(s), a steel column(s), a strut(s), a pile cap(s) (precast or cast in place), a pier cap(s) (precast or cast in place), a bent cap(s), any other main pier element known in the art, and combinations thereof, and (c) superstructures comprised of precast girders, cast in place box girders, precast box girders, segmental box girders, hollow slabs, steel girders, steel box girder, any other main superstructure elements known in the art, and combinations thereof. 
     With continuing reference to  FIG. 2 , for the purpose of describing the method in which the apparatus is used to construct a bridge, the substructure  84  is comprised of a last or latest pier structure  86  and a first pair of pier structures  88 . The first pair of pier structures  88  is comprised of a penultimate pier structure  90 , i.e., the pier structure that is next to the last pier structure  86 . Each of the pier structures is comprised of a plurality of piles  92  and a pier or pile cap  94 . 
       FIG. 3  illustrates the positions to which the center support  66 A, rear support  66 B, and the center auxiliary support  68 A are moved with the trolley structure  54  to enable the truss structure to be repositioned  52  so that girders can be erected between the lead pier structure  86  and the penultimate pier structure  90  and a new lead pier can be established. Specifically, the center auxiliary supports  68 A have been moved forward to a location just behind the penultimate pier structure  90 . Subsequently, the center support  66 A has been moved from the penultimate pier structure  90  to the lead pier structure  86 . Subsequently, the rear support  66 B has been moved forward to a location substantially adjacent to the pier that precedes the penultimate pier structure  90 . 
       FIG. 4  illustrates the repositioning of the truss structure  52  so that girders can be established between the lead pier structure  86  and the penultimate pier structure  90  and a new lead pier can be established. The truss structure  52  is moved using motor assemblies (not shown) that are associated with the center support  66 A, rear support  66 B, trolley structure  54 , and/or an external force applying structure. Movement of the truss structure  52  also repositions the center auxiliary supports  68 A immediately behind the center support  66 A and the rear auxiliary supports  68 B immediately behind the rear support  66 B. 
       FIG. 5  illustrates the delivery of a girder  100  that is to be erected between lead pier structure  86  and the penultimate pier structure  90 . 
       FIG. 6  illustrates the use of the first and second main trolleys  62 A,  62 B in lowering the girder  100  into place between the lead pier structure  86  and the penultimate pier structure  90 . As should be appreciated, the apparatus  50  is used to position the girder  100  but the establishment of a welded, bolted, or other suitable connection between the girder  100  is not done by the apparatus  50  but by other means. This is also the case with other elements of the bridge. 
       FIG. 7  illustrates the use of the first and second main trolleys  62 A,  62 B in lowering a final girder of a plurality of girders that extend between the lead pier structure  86  and the penultimate pier structure  90  into place. It should be appreciated that in establishing the plurality of girders between the lead pier structure  86  and the penultimate pier structure  90 , the truss structure  52  moves laterally. The lateral movement is accomplished by motor assemblies associated with the center support  66 A and the rear support  66 B as is known in the art. 
       FIG. 8  illustrates the delivery of a pile  110  that will be part of a new lead pier structure that the apparatus  50  will be used to establish at a location beyond the current lead pier structure  86 . 
       FIG. 9  illustrates the use of the trolley structure  54  to lower the pile  110  onto the lead assembly  58 , which in the illustrated embodiment comprises a hammer for use in driving the pile into the ground, a guide system for holding the pile in the lead and guiding the pile during the hammering of the pile into the ground, and a winch for lowering the hammer and the pile  110  until the pile engages the ground and thereafter lowering the hammer as the pile is driven into the ground. The pile  110  is received by a guide and engaged by a collar clamp that prevents the pile  110  from slipping during rotation of the pile into position for driving into the earth. Further, the pile  110  is positioned so that an end of the pile is located adjacent to the hammer that is used to drive the pile into the earth. 
       FIG. 10  illustrates the use of the lead assembly  58  to rotate the pile  110  into a position that is suitable for driving the pile  110  into the earth. 
       FIG. 11  illustrates the use of the lead assembly  58  to lower the pile  110  to the point at which the distal end of the pile  110  engages the earth and can be driven into the earth using the hammer associated with the lead assembly  58 . 
       FIG. 12  illustrates the apparatus  50  after the lead assembly  58  has been used to drive several piles that are associated with a yet to be completed, new lead pier  120  into the earth and the delivery of a first pier cap form or pre-cast shell  122 A that will be placed on top of a number of the piles of the new lead pier  120 . 
       FIG. 13  illustrates the use of the first main trolley  62 A to lower the first pier cap form or pre-cast shell  122 A onto several of the piles of the new lead pier structure  120 . Prior to the lowering of the first pier cap form or pre-cast shell  122 A onto the piles, the hammer associated with the lead assembly  58  was removed from the lead assembly  58 . The removal of the hammer reduces the force that is applied to the truss structure  54  during the establishment of the pier cap of the new lead pier structure  120 . In appropriate circumstances, removal of the hammer may not be necessary. In addition, prior to the lowering of the first pier cap form or pre-cast shell  122 A onto the piles, the lead portion of the lead assembly  58  was rotated into the illustrated upright position so as not to interfere with the lowering of the first pier cap form or pre-cast shell  122 A onto the piles. 
       FIG. 14  illustrates the use of the first main trolley  62 A to lower the second pier cap form or pre-cast shell  122 B onto a number of the piles associated with the new lead pier structure  120 . 
       FIG. 15  illustrates the use of the first main trolley  62 A to lower rebar and/or cement into the cap form or pre-cast shell created by the first and second pier cap forms or pre-cast shells  122 A,  122 B, thereby establishing the cap  94  of the now completed, new lead pier structure  120 . At this point, the lead portion of the lead assembly  58  can be rotated to a substantially horizontal position so that the hammer can be reattached to the assembly  58 . Further, upon repositioning the first main trolley  62 A and the first auxiliary trolley  64 A, the apparatus  50  is in substantially the same orientation as shown in  FIG. 2 . Consequently, the process can be repeated to establish girders between the new lead pier structure  120  and the now old, lead pier structure  82  and to establish a newer lead pier structure beyond the new lead pier structure  120 . It should be appreciated that the sequence of steps followed in constructing the bridge can be varied. For example, after the truss structure  52  is positioned as shown in  FIG. 4 , the piles could be driven for the new lead pier structure  120  before the girders are erected between the lead pier structure  86  and the penultimate pier structure  90 . As another example of a variation in the sequence of steps followed in constructing the bridge, the operations of driving a pile for the new lead pier structure  120  and the erection of a girder between the lead pier structure  86  and the penultimate pier structure  90  can be alternated with one another. Typically, there are several different operations that can be performed at any given point in time using the apparatus  50  with the timing of the delivery of elements needed to construct the bridge typically being determinative of the operation that the apparatus is used to perform at any particular point in time. 
     With reference to  FIGS. 16A-C , the lead assembly  58  is described in greater detail. The assembly  58  is comprised of a truss or lead  70 , a guide  72  for receiving a pile, a collar clamp  74  for guiding and gripping a pile, a hammer  76  for repeated striking of one end of a pile to drive the pile into the earth, a cord  78  for connecting the collar  74  to the hammer  76 , a cable/pulley/winch system  80  for controlling the position of the hammer  76  relative to the lead  70 , a two-axis pivot joint  82  that connects the lead  70  to the truss  52 , and a hydraulic system  84  for rotating the lead  70  about the pivot joint  82 . The two axes of the pivot joint  82  are typically perpendicular to one another. The guide  72  and the collar clamp  74  preferably are each of a clam-shell type of design that allows two halves to be separated so as to receive a pile from the trolley structure  54 . 
     In operation, the assembly  58  is initially in a substantially horizontal position, as shown in  FIG. 16A . To receive a pile, the guide  72  and the collar  74  are placed in an open position. After a pile has been received, the guide  72  and collar  74  are placed in a closed position. When the guide  72  and the collar  74  are in the closed position, the pile is substantially fixed in a position relative to the lead  70 . In this regard, the collar  74  holds the pile, and the cord  78  that is connected to the hammer  76  prevents the pile from moving longitudinally, i.e. in the direction of the longitudinal axis of the lead  70 , absent movement allowed by the cable/pulley/winch system  80 . The guide  72  and the collar  74  also prevent the pile from rolling off of the lead  70 . 
     After the pile has been fixed in position relative to the lead  70 , the hydraulic system  84  is used to rotate the pile about the two-axis pivot joint  82  to a desired orientation. In this regard, the hydraulic system  84  is comprised of a first and second hydraulic actuators  86 A,  86 B and a third hydraulic actuator  88  that both engage a shuttle  90  that is engaged to the lead  70  and whose position along the lead depends on length of the first and second hydraulic actuators  86 A,  86 B and the third hydraulic actuator  88 . By appropriate manipulation of the first and second hydraulic actuators  86 A,  86 B and the third hydraulic actuator  88 , the lead  70  and any associated pile can be positioned at a desired angle within a vertical plane that is substantially parallel to the longitudinal axis of the truss structure  52  or, stated differently, at a desired rotational position relative to the first axis of rotation provided by the two-axis pivot joint  82 . The first and second hydraulic actuators  86 A,  86 B also allow the rotational position of the lead  70  and any associated pile within a plane that is transverse to the longitudinal axis of the truss structure  52  (or, stated differently, within a plane that is substantially parallel to or passes through the first axis of rotation provided by the two-axis pivot joint  82 ) to be adjusted. This is accomplished by adjusting the lengths of the first and second hydraulic actuators. To elaborate, when the lengths are equal, the lead  70  is positioned as shown in  FIG. 16C . However, when the lengths are unequal, the lead  70  is rotated clockwise or counter-clockwise relative to the position of the lead  70  in  FIG. 16C . During rotation of the pile, the cable/pulley/winch system  80  prevents movement of the hammer  76 ; the cable  78  that is attached to the hammer  76 , in turn, prevents movement of the collar  74 ; and the collar  74 , in turn, prevents, movement of the pile relative to the collar. Consequently, the position of the pile is maintained during rotation of the pile by the assembly  58 . It should be appreciated that rotation of the lead  70  can be accomplished using any number of other mechanical devices and combinations of mechanical devices known in the art or readily conceived by those skilled in the art. For example, a winch, cable, and pulley system or a system that includes one or more motorized screws could be used to adjust the rotational position of the lead. 
     After the desired rotational position of pile has been achieved, the cable/pulley/winch system  80  is used to lower the hammer  76  and the pile until the distal end of the pile engages the earth into which the pile is to be driven. At this point, the cable  78  becomes slack and the hammer  76  is used to drive the pile into the earth. 
       FIG. 17  illustrates an embodiment of the collar  74 , hereinafter referred to as clamp pile collar clamp  130 , that is suitable for engaging a pile with a square cross-section. It should be appreciated that clamps are feasible for piles with different cross-sections, such as a circular cross-section. The clamp  130  is comprised of a first and second C-shaped members  132 A,  132 B, which are pivotably connected to one another by a hinge pin  134 . Respectively located on the interior surfaces of the first and second members  132 A,  132 B are first and second friction surfaces  136 A,  136 B that, in operation, engage a pile to prevent the pile from slipping relative to the clamp  130 . A tensioner/lock assembly  138  allows the clamp  130  to be placed in an open condition in which at least one of the members  132 A,  132 B rotates about the axis defined by the hinge pin  134  so that a pile can be placed within the clamp  130 . After a pile has been placed in the clamp  130 , at least one of the members  132 A,  132 B is rotated about the axis defined by the hinge pin  134  so as to place the clamp in a closed position, substantially as shown in  FIG. 17 . The tensioner/lock  138  is then used to fix the position of the first and second members  132 A,  132 B to one another and pull the first and second members  132 A,  132 B towards one another to apply a sufficient gripping force to the pile. 
     In many situations, a pile can be guided using only the guide  72 . Consequently, the collar  74  is not mounted to the lead  70 . If, however, it is desirable that the collar  74  also assist in guiding a pile, the collar  74  can be slidably mounted to the lead  70 . In the illustrated embodiment, the clamp  74  can be slidably mounted to in a number of ways known or conceivable to those skilled in the art. For example, the clamp  74  can incorporate C-shaped brackets that engage the two rails that define the open side of the lead  74  that receives a pile or other object. In the case of the clamp  130 , two such C-shaped brackets can be mounted to the appropriate one of members  132 A,  132 B to achieve a slidable mount. 
     Other clamps or devices for holding a pile or similar structure are feasible. For example,  FIG. 18A  illustrates a holder  200  that is suitable for receiving a pile or similar structure with a circular cross-section and through which a transverse hole has been established. The holder  200  comprises first and second members  202 A,  202 B that are connected to one another by a hinge joint  204 . A connector  206  is used to fix the first and second members  202 A,  202 B to one another after a pile has been received. The first and second members  202 A,  202 B respectively have pin holes  208 A,  208 B for receiving a pin  210  that also passes through the hole in the pile, column, or other bridge element. The pin  210  has first and second cotter pin holes  212 A,  212 B that respectively receive cotter pins  214 A,  214 B, to fix the pin  210  in place relative to the first and second members  202 A,  202 B. 
       FIG. 18B  illustrates another clamp that can hold a pile or similar object. In this case, clamp  220  has first and second members  220 A,  220 B that are connected to one another by a hinge joint and fixed together by a connector, just as with the clamp  130  and holder  200 . The first and second members  220 A,  220 B respectively have male members  224 A,  224 B that engage a groove  226  in a pile  228  or similar structure. 
     The lead assembly  58  can be used to receive columns and other similar structures that do not require the use of a hammer to be put in place, rotate the column or similar structure, and lower the column or similar structure into place. With respect to the placement of such structures, the lead assembly  58  does not need to incorporate a hammer. 
     The lead assembly  58  can also incorporate tools other than a hammer. With reference to  FIG. 19 , the lead assembly  58  comprises a drill  300 . The drill  300  is comprised of a bit  302 , a motor  304 , a kelly bar  306  for connecting the motor  304  to the bit  302 , and mounts  308 A,  308 B for slidably mounting the motor  304  to the two rails  310 A,  310 B that define the open side of the lead  70 . The cable, pulley, and winch system  80  is used to control the position of the drill  300  relative to the lead during the drilling operation. In this regard, the cable  312  is attached to the motor  304 . In an alternative embodiment, a pass-through motor is mounted to the lead  70  with a fixed or semi-fixed bracket that allows the motor to move up and down the lead for a limited distance. The Kelly bar and drill bit are suspended using the winch and cable. The motor is designed to allow the kelly bar to pass through an opening that is designed to transfer torque from the motor to the Kelly bar and the drill bit. 
       FIG. 20  illustrates a tailings removal system  400  for removing the drill tailing produced during operation of the drill  300  or other excavation tool that might be associated with the lead assembly  58 . The tailings removal system  400  is attached to the underside of the truss structure  52  and positioned so as to receive the drill bit  302  of the drill  300  that is attached to the lead  70 . The system  400  comprises an upper casing  402  that has a lower opening  404  and through which the drill bit  302  passes, a guide box  406  with a hole  408  ( FIG. 21 ) through which the drill bit  302  can pass, a cover plate  410 , a hydraulic actuator  412  for moving the cover plate  410  so as to cover and uncover the hole  408 , a rake  414  for use in pushing drill tailings off of the cover plate  410  when the cover plate  410  is covering the hole  408 , a hydraulic actuator  416  for moving the rake  412 , a hopper  418  for receiving tailings that either slide of the cover plate  410  when the cover plate  410  is covering the hole  408  or are pushed off of the cover plate  410  by the operation of the rake  414  and hydraulic actuator  416  when the cover plate  410  is covering the hole  408 , a conveyor  420  for receiving tailings from the  418  and conveying the tailings to a desired location. Associated with the upper casing  402  is a vibrator  422  that, if needed, can be used to shake tailings free from the drill bit  302  when the drill bit  302  has been retracted into the upper casing  402 . Similarly, associated with the hopper  418  is a vibrator  424  that, if needed, can be used to shake tailings free from the hopper  424 . The vibrators  422 ,  424 , are typically needed when the tailings are comprised of material that has a high clay content or is very viscous. Depending on the material being excavated, the vibrators  422 ,  424  may or may not be needed. It should also be appreciate that the cover plate  410  and rake  414  can each be actuated by other types of actuators. For example, a motorized screw or rack-and-pinion type of actuator can be used, as well as other types of actuators known in the art. 
     Prior to the use of the drill  300  to excavate a hole and the use of the system  400  is remove the tailings produced by the excavation, a lower casing  428  is driven into the ground. Typically, the lower casing  428  is driven into the ground using the lead assembly  58  with an associated hammer. The lower casing  428  serves both to guide the drill bit  302  and, once a sufficient amount of material has been excavated by the drill bit  302 , contain the tailings as the drill bit  302  is retracted. 
     After the lower casing  426  is in place, excavation of a hole with the drill  300  and removal of the tailings with the system  400  commences with, if necessary, putting the drill  300  into place on the lead  70  and putting the system  400  in place on the truss structure  52 . Typically, the trolley structure  54  is used to put the drill  300  into place on the lead  70 . Putting the drill  300  into place on the lead  70  may involve using the trolley structure  54  to remove a tool that is already attached to the lead  70 , such as a hammer, and then use the trolley structure  54  to place the drill  300  in place. The trolley structure  54  is also used to position the elements of the system  400  for attachment to the truss structure  52 . 
     With the drill  300  in place on the lead  70  and the system  400  operatively attached to the truss structure  52  with the cover plate  410  and the rake  412  each retracted as shown in  FIG. 20 , the excavation of a hole using the drill  300  and the excavation of the tailings therefrom commences with the rotation of the lead  70  so that the drill bit  302  is aligned from insertion through the upper casing  402  and the lower casing  426 . Once aligned, the cable, pulley, winch system  80  is used to lower the drill until the drill bit  302  engages the ground. Typically, the drill  300  is activated to begin rotating the drill bit  302  before the bit engages the ground. Excavation commences when the drill bit  302  has engaged the ground and the drill  300  has been activated. The weight of the motor  304  and other elements of the drill  300  that are located above the drill bit  302  is used to force the bit into the ground. In many case, this weight is too great for the type of drill bit being used and/or for the earth that is being excavated. In such cases, the cable, pulley, winch system  80  is used to moderate the force being applied to the drive the drill bit  302  into the ground. 
     Once the drill bit  302  has progressed a certain distance into the ground, the cable, pulley, winch system  80  is used to retract the drill bit  302  into the upper casing  402 . After the tip of the drill bit  302  moves past the top of the lower casing  426 , the hydraulic actuator  412  is used to position the cover plate  410  over the hole  408  of the guide box  406 . At this point, excavated material may fall of the drill bit  302  and onto the cover plate  410  and guide box  406 . After the tip of the drill bit  302  moves past the lower opening  404  of the upper casing  402 , the hydraulic actuator  416  can be used, if needed, to push any excavated material that has fallen off of the drill bit  302  into the hopper  418 . 
     Excavated material may naturally fall off of the drill bit  302  and onto the cover plate  410  and guide box  406 . Further, this material may slide down the cover plate  410  and the guide box  406  and into the hopper  418  without any assistance. If, however, the material either does not slide down the cover plate  410  and the guide box  406  or does so too slowly, the rake  414  and hydraulic actuator  416  can be employed to force the material into the hopper  418 . In many cases, the excavated material does not naturally fall off the drill bit  302 . In such cases, the vibrator  422  is used to shake the material off of the drill bit so that the material falls onto the cover plate  410  and the guide box  406 . The material can then, if needed, be pushed into the hopper  418  using the rake  414  and hydraulic actuator  416 . It should be appreciated that regardless of the consistency of the excavated material, the rake  414  may be actuated at a desired frequency. Moreover, the actuation of the rake  414  may be coordinated with the operation of the vibrator  422 . For example, the vibrator  422  could activated to cause material to fall onto the cover plate  410  and guide box  406  while the rake  414  is retracted, and then the vibrator  422  can be deactivated and the rake  414  actuated to push the material that previously fell onto the cover plate  410  and guide box  406  into the hopper  418 . This cycle can be repeated as needed. 
     Excavated material that is in the hopper  418  is dispensed onto the conveyor  420 , which transports the material to a desired location for disposal. The material may naturally flow out of the hopper  418  and onto the conveyor  420 . If, however, the material is of a consistency that such a natural flow does not occur, the vibrator  424  can be utilized to force the material out of the hopper  418  and onto the conveyor  420 . 
       FIG. 22  illustrates a ground engagement structure  600  that is attached to the lead  70  and can be extended from the bottom of the lead  70  to engage the ground. The ground engagement structure  600  engages the lead  70  in a manner comparable to an extension ladder. When engaging the ground, the structure  600  and the lead  70  operate to apply a force to the truss structure  52  that counteracts the force that is applied to the truss structure when the lead assembly is being used to drive a pile or other significant force is being applied adjacent to the terminal end  61 B of the truss structure. The ground engagement structure  600  is extended and retracted using a hydraulic actuator  602 . However, it should be appreciated that other types of actuators can be employed. 
       FIG. 23  schematically illustrates a second embodiment of a lead assembly  700  that comprises a lead  702 , a two-axis pivot joint  704  for connecting the lead  702  to the truss structure  52 , a winch  406 , a cable  408  that extends from the winch  406  to the lead  702 , and a pair of pulleys  410 A,  410 B that guide the cable  408 , a hinged resistive element  412  that moderates the rotation of the lead  702  caused by the winch  406 . The hinged resistive element  412  provides resistance by utilizing a hydraulic element. It should be appreciated that the other resistive elements are feasible, including elements that are not hinged. In operation, the winch  406  and cable  408  are used to move the lead  702  to a desired rotational position about an axis that is transverse to the longitudinal axis of the truss structure. The hinged resistive element  412  moderates the rotational operation. 
       FIG. 24  illustrates a second embodiment of a device  800  for use in causing the lead to rotate in a plane that is transverse to the longitudinal axis of the truss structure  52 . The device  800  comprises a curved plate  802  that is fixed to a lead  804 , a slotted box  806  that receives the plate  802 , a hydraulic actuator  808  with a cylinder that is pivotally attached to the slotted box  806  and a rod that is pivotally and operatively attached to the lead  804 , and a pivot attachment  810  for a support  812  that is attached to the truss structure  52  and not readily susceptible to rotation about the longitudinal axis of the truss structure  52 . In operation, the hydraulic actuator  808  is used to apply a force to the lead  804  that causes the lead to move relative to the slotted box  810  and, more specifically, to rotate in a plane that is transverse to the longitudinal axis of the truss structure  52 . 
       FIG. 25  illustrates a girder  140  that is the outer-most lateral girder of a bridge superstructure and the form  142  that must be attached to the girder  140  to create an L-shaped edge that is attached to the girder  140 . The L-shaped edge serves to contain concrete or other fluid material that is poured on top of the girder to establish the superstructure deck. In addition, the L-shaped edge provides a surface for attaching a lateral barrier, such as a fence. 
       FIG. 26  illustrates a girder  150  that is used in a bridge superstructure as the outer-most girder. The girder  150  is pre-cast so as to have a laterally extending portion  152  and a vertically extending portion  154  that is operatively connected to the laterally extending portion so as to form an L-shaped edge that is useful for containing concrete or other fluid material that is poured on top of the girder to establish the superstructure deck. If desired rebar  156  can be incorporated into the vertically extending portion  154  of the girder. It should be appreciated that the edge can be other shapes that serve the various purposes for which an edge is used on a bridge superstructure. 
     The embodiments of the invention described above are intended to describe the best mode known of practicing the invention and to enable others skilled in the art to utilize the invention.