Abstract:
A cable suspended hermetic structure having a floor and walls combining with the undersurface of superstructure substructure such as a bridge forming an enclosure defining a workspace wherein one or more persons having access to the bridge substructure can work to repair and maintain said structure while containing the debris derived from said work within the enclosed structure and where applicable an external source of filtering air can be connected to the interior of the enclosure without comprising the hermetic nature of the enclosure.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to bridges and, more specifically, to temporary suspended work platforms comprising a floor and walls combining with the undersurface of a suspended bridge or roadway to form enclosure defining a workspace wherein one or more persons having access to the bridge or roadway superstructure can descend for repair and maintenance of the underside of said bridge or roadway. 
     The temporary suspended work platform has a floor consisting of a plurality of overlapping corrugated steel sheets substantially coplanar with the roadway. The corrugated steel sheets have a support structure thereunder comprising longitudinally positioned cables extending from the abutment members and perpendicular support members whereby said interlocking cables support the corrugated steel work platform, work crew, spent steel abrasives and relevant equipment and act as a dampening element against wind sheer caused by sealing the work platform to the bridge by means of flexible sheet material. 
     The flexible walls are releasably fastened to the periphery of the work platform and extend substantially vertical to the roadway where it is releasably attached by fasteners to the roadway by ties to the guiderails and may additionally be anchored between said guiderails by placing weights on the material extending between the guiderails. 
     Additionally the containment platform can be segmented by erecting partitions which seal one segmented section from the other. 
     2. Description of the Prior Art 
     There are other work platforms device designed for suspension. Typical of these is U.S. Pat. No. 629,935 issued to Sturgis on Aug. 1, 1899. 
     Another patent was issued to Sutton on Jun. 2, 1936 as U.S. Pat. No. 2,043,128. Yet another U.S. Pat. No. 2,057,092 was issued to Geib on Oct. 13, 1936 and still yet another was issued on Oct. 3, 1950 to Benson as U.S. Pat. No. 2,524,302. 
     Another patent was issued to Goodell on Feb. 5, 1963 as U.S. Pat. No. 3,076,522. Yet another U.S. Pat. No. 3,945,462 was issued to Griswold on Mar. 23, 1976. Another was issued to Barber on Jul. 7, 1981 as U.S. Pat. No. 4,276,959 and still yet another was issued on Mar. 14, 1989 to Eyerly as U.S. Pat. No. 4,811,530. 
     Another patent was issued to Lyras et al. on Aug. 8, 1989 as U.S. Pat. No. 4,845,419. Yet another U.S. Pat. No. 5,011,710 was issued to Harrison on Apr. 30, 1991. Another was issued to Margaritis on Apr. 5, 1994 as U.S. Pat. No. 5,299,655 and still yet another was issued on Oct. 21, 1997 to Uzawa as U.S. Pat. No. 5,678,654. 
     Another patent was issued to Apostolopoulos on Mar. 24, 1998 as U.S. Pat. No. 5,730,248. Yet another U.S. Pat. No. 5,911,288 was issued to Zafirakis on Jun. 15, 1999. Another was issued to Apostolopoulos on Jul. 13, 1999 as U.S. Pat. No. 5,921,346 and still yet another was issued on Dec. 21, 1999 to Apostolopoulos as U.S. Pat. No. 6,003,634. 
     Another patent was issued to Apostolopoulos on Oct. 24, 2000 as U.S. Pat. No. 6,135,240. Yet another U.S. Pat. No. 6,138,793 was issued to Apostolopoulos on Oct. 31, 2000. Another was issued to Apostolopoulos on May 8, 2001 as U.S. Pat. No. 6,227,331. Another was issued on Jul. 24, 2001 to Apostolopoulos as U.S. Pat. No. 6,242,002 and still yet another was issued on Oct. 16, 2001 to Apostolopoulos as U.S. Pat. No. 6,302,237. 
     U.S. Pat. No. 629,935 
     Inventor: Nelson H. Sturgis 
     Issued: Aug. 1, 1899 
     The invention in a suspension bridge is the combination with columns, and anchored main cables, of hanger rods fast with the main cables and carrying the needle-beams, anchored joist cables laid on the needle-beams, side cables joined to the hanger-rods and fitted below the ends of the needle-beams, horizontal truss cables fitted around the ends of the needle-beams, and a floor laid on the joist-cables, substantially as described. 
     U.S. Pat. No. 2,043,128 
     Inventor: Cyril D. Sutton 
     Issued: Jun. 2, 1936 
     The invention is a scaffold including a platform having a permanent deck formed with a substantially centrally located opening which is adapted to accommodate a vertical structural member when the scaffold is arranged in position and being formed with a passage which leads from the margin of said platform to said opening, whereby said platform may be moved laterally to position said member in said opening, a floor section carried by said platform which is movable to cover the greater part of said passage when said member occupies said opening, an auxiliary floor section which is movable to cover the remainder of said passage, said auxiliary section being available to increase the size of said opening when necessitated by the use of the platform in connection with a larger structural member and means for supporting said platform at a determined height with respect to said first mentioned member. 
     U.S. Pat. No. 2,057,092 
     Inventor: Robert Lewis Geib 
     Issued: Oct. 13, 1936 
     The invention discloses means for supporting one platform at right angles to another platform comprising a bracket, said bracket comprising a pair of parallel T shaped flanges connected by a tierod, one side of the vertical portions of said T comprising means for supporting a platform, the horizontal branches of said T which extend on the other side of the vertical portions thereof comprising means for supporting said bracket by the side of the supporting platform. 
     U.S. Pat. No. 2,525,302 
     Inventor: Jesse Mack Benson 
     Issued: Oct. 3, 1950 
     The invention is a scaffold supporting bracket comprising a pair of elongated oppositely disposed parallel extending angle members on which planks may be supported, means securing said angle members together in spaced apart relation longitudinally thereof, a first supporting rod having a loop formed on one end loosely extending between said angle members at one end of the latter, pivot means carried by said angle members extending through said loop for rockably connecting said rod to said angle members, a second supporting rod having a loop formed on one end extending loosely between said angle members at the other end thereof, pivot means extending through the loop of said second supporting rod for rockably connecting said second rod to said angle members, and bent tabs formed on the opposite ends of said angle members closing the space between the latter and engageable with the adjacent ones of said supporting rods for limiting the rocking of said rods away from said angle members. 
     U.S. Pat. No. 3,076,522 
     Inventor: Harvey L. Goodell 
     Issued: Feb. 5, 1963 
     The invention discloses a scaffold apparatus for use on an elevated roadway comprising an elongated upstanding mobile frame adapted to straddle and rest upon an elevated roadway, a vertically disposed support member mounted on one end of said mobile frame and having a portion extending below said mobile frame, the lower end of said mobile frame extending vertically beneath the roadway, and a horizontally disposed walkway mounted on said support member for swinging movement in clockwise and counterclockwise directions of said walkway about said support member as a vertical axis into and out of position below and in longitudinal alignment with said frame, said walkway, when said mobile frame straddles and rests upon an elevated roadway, being of a length to extend beneath said roadway and adapted to support workmen thereon for the purpose of treating the underside of said roadway. 
     U.S. Pat. No. 3,945,462 
     Inventor: James D. Griswold 
     Issued: Mar. 23, 1976 
     Hanger brackets for suspending working scaffold or platform floors from overhead supports. Paired legs adjustably and pivotally joined together in scissors arrangement have finger ends for engaging overhead beams or elements thereof as depending portions of the legs that extend beneath the center pivot are moved inwardly. A spreader bar having a plurality of position adjustment openings is engaged between the depending legs to lock the fingers and bracket in place. The lower leg ends also provide a plurality of adjustment openings so the spreader bar may be engaged at alternate elevations for accommodating various staging or joist type components and for facilitating the attachment of safety elements. 
     U.S. Pat. No. 4,276,959 
     Inventor: Ronald A. Barber 
     Issued: Jul. 7, 1981 
     In the preferred and illustrated embodiment, a scaffold is shown for attachment on the bottom side of an offshore drilling rig or platform. The scaffold is quickly installed and removed. It is fabricated with a set of upright hanger straps which, in turn, clamp to eye beams spanning the bottom side of the offshore structure. The hanger straps incorporate opposing hooks at the upper end. The central portion is comprised of an elongate strap or hanger, the length accommodating workmen. Each strap terminates at its lower end with a support to receive framing members such as horizontally deployed structural beams. The beams support deck planking arranged horizontally thereon and spaced from the bottom side of the offshore structure. 
     U.S. Pat. No. 4,811,530 
     Inventor: Jon V. Eyerly 
     Issued: Mar. 14, 1989 
     A portable platform is formed of a plurality of elongated floor support members interconnected longitudinally and spaced apart laterally, the support members having a plurality of longitudinally spaced cross members, the confronting cross members being secured in alignment by interengaging coupling members and the laterally spaced floor support members being secured against lateral displacement by a plurality of elongated locking members interengaging adjacent pairs of support members. A plurality of elongated floor members are supported on the foregoing assembly and are secured together releasably along their longitudinal edges. The perimeter of the assembly of floor members is secured against vertical displacement relative to the underlying support assembly by means of a plurality of perimeter floor hold-down members which are secured removably against vertical and longitudinal displacement by a plurality of perimeter floor hold-down support members removably connected to the outer ends of the support members and outwardly extending associated cross members. 
     U.S. Pat. No. 4,854,419 
     Inventor: Louis G. Lyras et al. 
     Issued: Aug. 8, 1989 
     A mobile containment platform method and system for sandblasting and the like in bridge reconditioning and painting that requires removal of paint from the support structure of the bridge. The containment platform provides a safe secure entrapment envelope for spent abrasive and removed paint residue. 
     U.S. Pat. No. 5,011,710 
     Inventor: John F. Harrison 
     Issued: Apr. 30, 1991 
     Surfaces of a structure are treated from a walkway within an enclosure suspended from the structure. The enclosure has a downwardly-converging cross section terminating in a vacuum conveyor for collecting and removing particles accumulating from the blasting process. The enclosure is preferably provided in modules. The vacuum conveyor removes the particulate material for transfer to conventional separating and re-cycling equipment. The enclosure and walkway are moveably suspended from transverse guideways secured to the structure. 
     U.S. Pat. No. 5,299,655 
     Inventor: Nicholas Margaritis 
     Issued: Apr. 5, 1994 
     An enclosed workplace support for temporary, immovable installation below and on each side of a bridge or other existing structure while performing work on bridge substructure. Double rows of upper and lower outriggers are installed to extend outwardly from each lateral side of the bridge and cables are attached to the outer ends of each row of outriggers. Additional cables are attached at opposite ends to bearings or other bridge substructure and extend parallel to the bridge centerline for an entire span. The cables support a high-strength flooring, preferably or rubber-coated chain link fencing. A nylon tarp is laid over the fencing below the bridge and extends around each side, attached to the outrigger cables, and is sealed to the bridge curbs. An exhaust blower maintains the interior of the enclosed workplace at subatmospheric pressure. 
     U.S. Pat. No. 5,678,654 
     Inventor: Katsuo Uzawa 
     Issued: Oct. 21, 1997 
     A hanging scaffold panel for use in a hanging scaffold has a rectangular frame with an elongate male portion projecting from one side and attached to the rectangular frame with a fixing pin. The rectangular frame has a female portion on a side opposing the male portion and adapted to receive a male portion from an adjoining panel. The elongate male portion has two semi-cylindrical sections that are threadably adjusted to engage the female portion. A fastening pin is used to lock the male portion in the female portion. 
     U.S. Pat. No. 5,730,248 
     Inventor: Lambros Apostolopoulos 
     Issued: Mar. 24, 1998 
     A bridge platform and method of erecting the same wherein a plurality of cables extend longitudinally of the bridge in spaced relation below the deck or roadway and steel support structure of the bridge, which cables are supported at opposite ends by the spaced-apart vertical piers of the bridge, and wherein a plurality of platform flooring panels or sections are supported on the cables, extend laterally of the bridge, are arranged side-by-side along the length of the bridge between the piers and are removably secured to the cables. The cables are attached to the bridge piers by compression clamp structures. The platform flooring sections comprise elongated rectangular corrugated decking panels and are arranged in end-to-end overlapping relation transversely of the bridge, side-to-side overlapping relation longitudinally along the bridge and with the corrugations extending transversely of the cables. The corrugations maximize the strength-to-weight ratio of the platform flooring and provide recesses or receptacles to contain debris and facilitate its collection and removal. Each of the platform flooring sections is releasably connected at spaced locations to the supporting cables on which it rests. This is provided by connector assemblies each comprising a first part which engages the upper surface of the flooring section and the cable and a second part which engages the upper surface of the flooring section, the two parts being removably connected together through a small opening in the flooring. As a result, individual flooring sections can be removed to provide access through the flooring in emergency or critical situations while at the same time allowing the remainder of the flooring to retain collected debris. 
     U.S. Pat. No. 5,911,288 
     Inventor: Gregory Zafirakis 
     Issued: Jun. 15, 1999 
     A work platform for temporary installation under a bridge span includes a plurality of longitudinal support cables supporting transversely extending grating planks, with sidewise adjacent planks being interlocked by lock pins. A selected subset of the grating planks are releasably fastened to underlying support cables T-shaped clamping members inserted through slots in the selected grating planks. 
     U.S. Pat. No. 5,921,346 
     Inventor: Lambros Apostolopoulos 
     Issued: Jul. 13, 1999 
     A bridge platform and method of erecting the same wherein a plurality of cables extend longitudinally of the bridge in spaced relation below the deck or roadway and steel support structure of the bridge, which cables are supported at opposite ends by the spaced-apart vertical piers of the bridge, and wherein a plurality of platform flooring panels or sections are supported on the cables, extend laterally of the bridge, are arranged side-by-side along the length of the bridge between the piers and are removably secured to the cables. The cables are attached to the bridge piers by compression clamp structures. The platform flooring sections comprise elongated rectangular corrugated decking panels and are arranged in end-to-end overlapping relation transversely of the bridge, side-to-side overlapping relation longitudinally along the bridge and with the corrugations extending transversely of the cables. The corrugations maximize the strength-to-weight ratio of the platform flooring and provide recesses or receptacles to contain debris and facilitate its collection and removal. Each of the platform flooring sections is releasably connected at spaced locations to the supporting cables on which it rests. This is provided by connector assemblies each comprising a first part which engages the upper surface of the flooring section and the cable and a second part which engages the upper surface of the flooring section, the two parts being removably connected together through a small opening in the flooring. As a result, individual flooring sections can be removed to provide access through the flooring in emergency or critical situations while at the same time allowing the remainder of the flooring to retain collected debris. 
     U.S. Pat. No. 6,003,634 
     Inventor: Lambros Apostolopoulos 
     Issued: Dec. 21, 1999 
     A bridge platform and method of erecting the same wherein a plurality of cables extend longitudinally of the bridge in spaced relation below the deck or roadway and steel support structure of the bridge, which cables are supported at opposite ends by the spaced-apart vertical piers of the bridge, and wherein a plurality of platform flooring panels or sections are supported on the cables, extend laterally of the bridge, are arranged side-by-side along the length of the bridge between the piers and are removably secured to the cables. The cables are attached to the bridge piers by compression clamp structures. The platform flooring sections comprise elongated rectangular corrugated decking panels and are arranged in end-to-end overlapping relation transversely of the bridge, side-to-side overlapping relation longitudinally along the bridge and with the corrugations extending transversely of the cables. The corrugations maximize the strength-to-weight ratio of the platform flooring and provide recesses or receptacles to contain debris and facilitate its collection and removal. Each of the platform flooring sections is releasably connected at spaced locations to the supporting cables on which it rests. This is provided by connector assemblies each comprising a first part which engages the upper surface of the flooring section and the cable and a second part which engages the upper surface of the flooring section, the two parts being removably connected together through a small opening in the flooring. As a result, individual flooring sections can be removed to provide access through the flooring in emergency or critical situations while at the same time allowing the remainder of the flooring to retain collected debris. 
     U.S. Pat. No. 6,135,240 
     Inventor: Lambros Apostolopoulos 
     Issued: Oct. 24, 2000 
     A bridge platform and method of erecting the same wherein a plurality of cables extend longitudinally of the bridge in spaced relation below the deck or roadway and steel support structure of the bridge, which cables are supported at opposite ends by the spaced-apart vertical piers of the bridge, and wherein a plurality of platform flooring panels or sections are supported on the cables, extend laterally of the bridge, are arranged side-by-side along the length of the bridge between the piers and are removably secured to the cables. The cables are attached to the bridge piers by compression clamp structures. The platform flooring sections comprise elongated rectangular corrugated decking panels and are arranged in end-to-end overlapping relation transversely of the bridge, side-to-side overlapping relation longitudinally along the bridge and with the corrugations extending transversely of the cables. The corrugations maximize the strength-to-weight ratio of the platform flooring and provide recesses or receptacles to contain debris and facilitate its collection and removal. Each of the platform flooring sections is releasably connected at spaced locations to the supporting cables on which it rests. This is provided by connector assemblies each comprising a first part which engages the upper surface of the flooring section and the cable and a second part which engages the upper surface of the flooring section, the two parts being removably connected together through a small opening in the flooring. As a result, individual flooring sections can be removed to provide access through the flooring in emergency or critical situations while at the same time allowing the remainder of the flooring to retain collected debris. 
     U.S. Pat. No. 6,138,793 
     Inventor: Lambros Apostolopoulos 
     Issued: May 8, 2001 
     A work platform for use on bridges wherein a plurality of cables extend along a section of the bridge in spaced relation below the deck or roadway and steel support structure of the bridge, which cables are supported at opposite ends by either the steel support structure of the bridge or by the spaced-apart vertical piers of the bridge, and wherein a plurality of platform flooring panels or sections are supported on the cables, extend laterally of the cables, are arranged side-by-side along the section of the bridge such as between the piers and are removably secured to the cables. In one aspect the cables are connected at each end exclusively to the bridge piers, and in another aspect the cables are connected at each end exclusively to the bridge steel structure. In the latter instance, there is provided the capability of installation on skewed or angled bridge sections. In both aspects there is capability of adjustment in vertical and horizontal directions. The platform flooring sections comprise elongated rectangular corrugated decking panels and are arranged in end-to-end overlapping relation transversely of the cables, side-to-side overlapping relation along the bridge and with the corrugations extending transversely of the cables. The corrugations maximize the strength-to-weight ratio of the platform flooring and provide recesses or receptacles to contain debris and facilitate its collection and removal. Each of the platform flooring sections is releasably connected at spaced locations to the supporting cables on which it rests. This is provided by connector assemblies comprising a first part which engages the upper surface of the flooring section and the cable and a second part which engages the upper surface of the flooring section, the two parts being removably connected together through a small opening in the flooring. As a result, individual flooring sections can be removed to provide access through the flooring in emergency or critical situations while at the same time allowing the remainder of the flooring to retain collected debris. A connector assembly also is provided which has a manually operated lever for selectively placing the connector assembly in clamped or unclamped positions relative to the cable and flooring section. The corrugated decking panels can be provided with hinged plates for covering the corrugations to provide a substantially flat surface over the panels. 
     U.S. Pat. No. 6,227,331 
     Inventor: Lambros Apostolopoulos 
     Issued: May 8, 2001 
     A bridge platform and method of erecting the same wherein a plurality of cables extend longitudinally of the bridge in spaced relation below the deck or roadway and steel support structure of the bridge, which cables are supported at opposite ends by the spaced-apart vertical piers of the bridge, and wherein a plurality of platform flooring panels or sections are supported on the cables, extend laterally of the bridge, are arranged side-by-side along the length of the bridge between the piers and are removably secured to the cables. The cables are attached to the bridge piers by compression clamp structures. The platform flooring sections comprise elongated rectangular corrugated decking panels and are arranged in end-to-end overlapping relation transversely of the bridge, side-to-side overlapping relation longitudinally along the bridge and with the corrugations extending transversely of the cables. The corrugations maximize the strength-to-weight ratio of the platform flooring and provide recesses or receptacles to contain debris and facilitate its collection and removal. Each of the platform flooring sections is releasably connected at spaced locations to the supporting cables on which it rests. This is provided by connector assemblies each comprising a first part which engages the upper surface of the flooring section and the cable and a second part which engages the upper surface of the flooring section, the two parts being removably connected together through a small opening in the flooring. As a result, individual flooring sections can be removed to provide access through the flooring in emergency or critical situations while at the same time allowing the remainder of the flooring to retain collected debris. 
     U.S. Pat. No. 6,264,002 
     Inventor: Lambros Apostolopoulos 
     Issued: Jul. 24, 2001 
     A work platform for use on bridges or other structures wherein a plurality of cables extend in spaced relation along a section of the structure and are supported by the structure and wherein a floor comprising a plurality of corrugated flooring panels or sections is supported on the cables and removably secured to the cables. The positions of the cables are adjustable in vertical and horizontal directions. A connector assembly releasably connects each of the platform flooring sections to a respective supporting cable on which it rests. Each connector assembly comprises a first part which rests on a bottom wall of the panel and has a portion which extends through an opening in the bottom wall and back through the opening and is connected to a second part to form an eyelet through which the cable passes. In aspects of the present invention, the first and second parts are connected by a lever or a wedge. The corrugated decking panels have hinged plates for covering the corrugations to provide a substantially flat surface over the panels while allowing nestability for storage and transport. In one aspect of the invention, a pair of floors are connected by a gutter and are inclined therefrom, and the cable positions are adjustable to vary the angle of inclination as well as to vary the height and spacing of the cables. The inclined floors are vibrated to effect removal of debris to the gutter where it may be more easily removed. 
     While these suspended work platforms may be suitable for the purposes for which they were designed, they would not be as suitable for the purposes of the present invention, as hereinafter described. 
     SUMMARY OF THE PRESENT INVENTION 
     A primary object of the present invention is to provide one or more containment suspended work platforms beneath an aerial roadway whereby maintenance can be performed. 
     Another object of the present invention is to provide one or more containment suspended work platforms having a plurality of horizontal cables forming platform support members spaced parallel to the aerial roadway and fastened to the roadway abutments. 
     Yet another object of the present invention is to provide one or more containment suspended work platforms having platform support cables fastened between cable slings fastened around the rocker bearing plates positioned between roadway abutments and roadway girders. 
     Still yet another object of the present invention is to provide one or more cable attachment anchor plates removably fastened to the roadway abutments. 
     Another object of the present invention is to provide one or more containment suspended work platforms having platform support cables fastened between said temporary abutment anchors. 
     Yet another object of the present invention is to provide one or more containment suspended work platforms having a plurality of horizontal cables forming platform support members spaced parallel to the aerial roadway and fastened to cable slings extending between abutment rocker bearings. 
     Still yet another object of the present invention is to provide a sheath for the cable slings at the corners of engagement with the abutment rocker plate. 
     Another object of the present invention is to provide one or more containment suspended work platforms using corrugated steel as the flooring for said platform. 
     Yet another object of the present invention is to provide one or more containment suspended work platforms wherein the corrugations of the steel can be used for the accumulation of maintenance debris. 
     Still yet another object of the present invention is to provide one or more containment suspended work platforms wherein the corrugations of the steel can be used as channels for the containment of steel cables. 
     Another object of the present invention is to provide one or more containment suspended work platforms wherein the corrugations of the steel can be used as recesses for the placement therein of J-bolts for fixedly positioning the corrugated steel to the cable support members. 
     Yet another object of the present invention is to provide one or more containment suspended work platforms wherein the corrugated steel sheet forms a rigid member for the attachment thereto of the flexible wall retention members. 
     Still yet another object of the present invention is to provide one or more containment suspended work platforms wherein the corrugated steel platform has one or more support members extending from the platform support cables to the opposing flanges of an aerial roadway support girder. 
     Another object of the present invention is to provide one or more containment suspended work platforms wherein the corrugated steel platform has one or more support members extending from the platform support cables to the exterior flanges of opposing aerial roadway support girders. 
     Yet another object of the present invention is to provide one or more containment suspended work platforms wherein the corrugated steel platform has one or more support members extending from the platform support cables forming a loop from said cable having a diaphragm girder passing therethrough. 
     Still yet another object of the present invention is to provide one or more containment suspended work platforms wherein the horizontal platform cable has one or more support members extending from the said cable to a hanger extending from the roadway parapet. 
     Another object of the present invention is to provide one or more containment suspended work platforms wherein the horizontal platform cable has a support member extending from the said cable to a hanger extending from the intersection of girder cross bracing. 
     Yet another object of the present invention is to provide one or more containment suspended work platforms wherein the horizontal platform cable has a support member extending from said cable to a hanger extending from the I-beam cross braces. 
     Still yet another object of the present invention is to provide one or more containment suspended work platforms wherein the steel sheets are covered by substantially similar material as the flexible walls and fastened thereto whereby cleanup of abrasive material is easier. 
     Additional objects of the present invention will appear as the description proceeds. 
     The present invention overcomes the shortcomings of the prior art by providing a support system for a work platform comprised of cables extending from roadway bearing members having a protective sheath where said cables engage said roadway bearing members. Further having cables fastened to the midpoint of cables secured between girder bearing members. Additionally having cables fastened to anchor plates temporarily bolted to roadway abutment members during the life of the suspended work platform. 
     The cables form a support network for the placement thereon of decking. In the preferred embodiment the decking material is corrugated steel plates having a thickness conforming to the live and dead load placed thereon by the men, equipment and maintenance debris. The decking is secured to the horizontal support cables by a plurality of J-bolts and in addition by inserting fasteners in overlapping plates. 
     The foregoing and other objects and advantages will appear from the description to follow. In the description reference is made to the accompanying drawing, which forms a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. In the accompanying drawing, like reference characters designate the same or similar parts throughout the several views. 
     The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims. 
     LIST OF REFERENCE NUMERALS UTILIZED IN THE DRAWINGS 
       10  suspended work platform 
       12  suspension roadway 
       13  suspended roadway guiderails 
       14  I-beams 
       16  suspension girder bays 
       18  steel plates 
       20  horizontal cables 
       21  cable slings 
       22  vertical cables 
       24  j-bolt 
       26  flexible wall 
       28  flexible wall retainer 
       30  flexible wall retainer fastener 
       32  partition frame 
       34  partition 
       36  ducts 
       38  abutments plates 
       40  bearings 
       42  bearing cables 
       44  diaphragm girders 
       46  hook-like fasteners 
       48  abutment 
       50  abutment plate anchors 
       52  horizontal cable shackle 
       54  cable fasteners 
       56  downrigger support cable 
       58  downrigger horizontal cable support 
       60  downrigger 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     In order that the invention may be more fully understood, it will now be described by way of example, with reference to the accompanying drawing in which: 
     FIG. 1 is an illustrated view of the present invention in use. 
     FIG. 2 is sectional view of the present invention installed on a beam bridge. 
     FIG. 3 is a top view of the horizontal platform support cable attachment. 
     FIG. 4 is a sectional side view of a horizontal platform support cable and girder bearing. 
     FIG. 5 is a plan view of a platform support cable fastened to an abutment beam. 
     FIG. 6 is a detail view of a mid-bay cable attachment. 
     FIG. 7 is a sectional view of the abutment plate installed. 
     FIG. 8 is a perspective view of an abutment plate. 
     FIG. 9 is a side view of a downrigger. 
     FIG. 10 is a sectional view of the containment area. 
     FIG. 11 is a side view girder attachment of the divider wall. 
     FIG. 12 is a side view of the suspended platform having perpendicular cable attached to I-beams. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following discussion describes in detail one embodiment of the invention (and several variations of that embodiment). This discussion should not be construed, however, as limiting the invention to those particular embodiments, practitioners skilled in the art will recognize numerous other embodiments as well. For definition of the complete scope of the invention, the reader is directed to appended claims. 
     Referring to FIG. 1, shown is a bridge  12  having a suspended platform  10  installed therefrom. The suspended platform provides a containment area below a suspended roadway whereby maintenance of the support structure can be perform. The suspended work platform is an enclosure where the debris from maintenance is contained therein. 
     Referring to FIG. 2, shown is a sectional view of the work platform suspended from one type of elevated roadway, a beam bridge  12 . The mid-bay hangers  22  are supported from the middle of each cross-brace and the platform support cables  20  are rigged between abutments and the outer platform support cables are secured to abutment plates  38  anchored into the concrete abutments. Shown is a corrugated platform  18  suspended below a suspension bridge  12  and a containment enclosure in the form of a tarp  26  being installed therearound to conform with D.O.T. specifications. The present invention is a rigging system and method for suspending a platform from a bridge structure  12  to allow workers to access the bottom portion thereof for maintenance purposes such as sandblasting, painting, structural inspections and the like. The present invention utilizes a combination of substantially vertical hanging cables  22  or chains suspended from beams  14  and girders to support substantially horizontal cables or chains  20  fastened to girder or abutment bearings. Overlapping sections of corrugated panels  18  are placed end to end and side to side on the horizontal cables  20  with the corrugations extending perpendicular in relation to the cables. Abutment plates  38  are anchored into the abutments to support the outer cable attachments  22 . The rigging system and method of the present invention is designed primarily for beam bridges but may also be used with suspension bridges or any other bridge or structure with which the application would be appropriate. 
     Referring to FIG. 3, shown is the platform  10  horizontal support cable  18  extending from cable slings  21 . Cable sling  21  is fastened to adjacent bearing plates  40 . Downriggers  60  are used to support the exterior cable  56  and are slidably locked onto the lower flange of the fascia girder. 
     Referring to FIG. 4, shown is a sectional side view of a horizontal platform support cable  20  having cable fasteners  54  and shackle  52  fastened to girder bearing  40 . The platform support cables  18  beneath the girders are fastened horizontally around the bearing masonry plates  40  using cable slings  21 . 
     Referring to FIG. 5, shown is a plan view of a platform  10  support cable  20  fastened to a bearing beam  40 . The platform support cable  20  is looped into a cable sling and secured around the bearing masonry plate  40  located on a pier or an abutment. Sections of heavy-duty blast hose  19  encompass the cable at the corners of the masonry plate  40  to maintain the integrity thereof. Three cable clips  54  secure a turnback that is no less than 12 inches long. The cable, shackle  52  and cable clips  54  form the choker assembly with the preferable diameter of the cable being ⅝″ with the accessories sized accordingly. If the internal angle of the of the choker assembly exceeds ⅝″ the cable diameter should be increased to ¾″. 
     Referring to FIG. 6, shown is a detail view of a mid-bay cable attachment. The mid-bay cable  21  attachments are rigged between girder bearings  40  at the abutments. Four cable clips  54  are preferred on the dead ends of the substantially horizontal cables and a minimum of three cable clips  54  are preferred on the vertical interior cable. 
     Referring to FIG. 7, shown is a sectional view of the abutment plate  38  installed. The outer platform support cables  20  are secured to abutment plates  38  that are anchored into the concrete abutments  48  with hilti bolts  50 . 
     Referring to FIG. 8, shown is a perspective view of an abutment plate  38  which is used to attach horizontal cable  18  to the bridge abutment  48 . 
     Referring to FIG. 9, shown is a side view of a downrigger  60 . The downriggers  60  are used to support the exterior horizontal cable  20  in a parallel position away from the structure. The buttress cable  56  is connected on one end to the distal end of the downrigger  60  and the other end is fastened to the bridge guide rails  13 . 
     Referring to FIG. 10, shown is a sectional view of the containment area  10 . The sides of the platform  10  are completely sealed by tarps  26  and one end has three evenly spaced exhaust ducts  36  leading to a mobile dust collector and the end opposite the exhaust ducts has air inlet openings installed in the plywood  34  within the girder bays. A divider wall will be installed to divide the containment area in two separate zones in the event that two mobile dust collectors are used with each zone having three evenly spaced exhaust ducts leading to one collector. 
     Referring to FIG. 11, shown is a side view girder attachment  14  of the divider wall. A divider wall when more than one mobile dust collector is used. The upper edge of the tarp  26  is sandwiched between the girder  14  and a firring strip  28  and secured therein by a c-clamp  30 . 
     Referring to FIG. 12, shown is the suspended platform  10  having steel plates  18  supported by a plurality of horizontal cables  20  having vertical cables/chains  22  having hook-like fasteners  46  attached to I-beams  14  and diaphragm beams  44 . The I-beams  14  reside on the bearings  40  having diaphragm beams positioned therebetween. Partition frame  32  which can be comprised of the flexible material  26  forming the exterior walls of the work enclosure  10  or constructed of wood frame material covered by plywood whereby the enclosure can be subdivided into more than one enclosed workspace. The flexible wall  26  can be attached to the roadway guardrails  13  at the top end and fastened the platform  18  by means of flexible wall retainer  28 .