Patent Publication Number: US-6338175-B2

Title: Movable safety tunnel for use during bridge maintenance

Description:
This is a continuation of application Ser. No. 09/388,818, filed Sep. 1, 1999, now U.S. Pat. No. 6,170,106. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a movable shield and containment system for the maintenance of existing bridges and, more particularly, to a “safety tunnel” which is movable with respect to the bridge structure to facilitate traffic flow along the roadway of the bridge (and/or under the bridge) while protecting the traffic flow from falling debris during the maintenance work on the bridge. 
     BACKGROUND OF THE INVENTION 
     Existing bridges require substantial maintenance. The maintenance is required at least periodically, if not continuously. For example, it is often necessary to remove the paint (such as a lead-based paint) from the steel structure of a bridge prior to applying a new coating thereto. To remove the paint, conventional sand-blasting or shot-blasting equipment is used. Suitable available measures are taken (as hereinafter discussed) to prevent the debris from falling onto the roadway, or into any water below the bridge, or otherwise polluting the environment. 
     At the same time, it is also very desirable to facilitate the continuous traffic flow along the roadway, while the maintenance is being performed, and thus avoid a complete shutdown of the traffic flow. While the traffic flow is primarily vehicular or railway traffic, it is also desirable to maintain any pedestrian traffic as well as facilitate access for the maintenance crews. By maintenance, it is understood that any repair or construction on the bridge is contemplated herein. 
     To maintain the traffic flow while the maintenance is being performed, the prior art has resorted to the use of a shield and containment structure (commonly referred to as a “traffic shield”) constructed within or under the bridge, along a given length thereof, and above the deck or roadway of the bridge. 
     This conventional traffic shield, together with the roadway, provides a complete enclosure for the traffic flow (which may be vehicular, railway, pedestrian or some combination thereof). Within the traffic shield (or thereunder) the traffic is protected against any falling debris—such as paint chips from the bridge, the materials of shot blasting or sand blasting, and any tools, components or structural elements accidentally dropped by the maintenance workers. By the same token, the workers are protected against the vehicular or rail traffic. As a result, a complete shut-down of the bridge is avoided, and the traffic flow is substantially unimpeded while the maintenance is being performed. 
     However, when the maintenance has been completed on a given length or section of the bridge, the traffic may be halted for a substantial period of time sufficient to enable the workers to completely dismantle the traffic shield, move its individual components to the next successive section of the bridge, and then re-assemble the traffic shield therein. This is time-consuming, hence expensive, and causes a substantial traffic problem; and a need exists for a more efficient solution to this long-standing problem. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, it is the primary object of the present invention to alleviate the disadvantages and deficiencies of the prior art by providing a movable safety tunnel within the bridge, thereby resulting in a substantial cost-savings and, concurrently, holding the inconvenience to the motorists to an absolute minimum. 
     The present invention finds particularly utility for use in connection with a bridge having a roadway for vehicular and/or pedestrian traffic, wherein maintenance is being performed on the bridge, and wherein a safety tunnel is constructed within a respective longitudinal section of the bridge. Accordingly, the traffic flows on the roadway of the bridge substantially uninterrupted while the maintenance is being performed on the respective longitudinal section of the bridge. More specifically, the traffic on the roadway of the bridge is protected against falling debris, such as paint particles, materials for shot blasting or sandblasting, tools, components and the like. At the same time, the workers performing the maintenance are shielded from the traffic flow. Once the maintenance on the respective longitudinal section of the bridge is completed, the traffic shield is normally dismantled and thereafter reconstructed on a next adjacent longitudinal section of the bridge. 
     In the improvement of the present invention, the traffic shield comprises a safety tunnel which is movable along the length of the bridge. 
     As a result, the necessity for repeatedly dismantling and reconstructing a conventional traffic shield is eliminated (as the maintenance on the bridge progresses along the length of the bridge). 
     For example, and in comparison to the prior art, if the bridge is sixteen hundred (1600) feet long, and if the conventional traffic shield is one hundred (100) feet long, it will have to be assembled, disassembled and re-assembled approximately sixteen (16) times. Thus is time-consuming and expensive and a distinct inconvenience, repeatedly, for the vehicular traffic on the bridge. With the present invention, however, the safety tunnel may be rolled from place to place along the bridge without requiring the safety tunnel to be taken apart. 
     In a preferred embodiment of the present invention, rails are constructed on top of the respective parapets running along the respective sides of the deck or roadway of the bridge, and the movable safety tunnel has a trolley system riding on the rails. 
     The trolley system is locked to a respective longitudinal section of the rails as the maintenance is being performed on a corresponding respective length of the bridge; and the trolley system is unlocked from the respective longitudinal section of the rails to enable the safety tunnel to be moved to the next adjacent section of the bridge on which the maintenance is to be performed. The safety tunnel is pushed and/or pulled by a tow truck (or other suitable piece of equipment) to the next adjacent section of the bridge. 
     Preferably, the trolley system comprises a plurality of respective spaced-apart trolley assemblies. 
     In the preferred embodiment, the safety tunnel includes an inverted U-shaped structure having a roof assembly joined to respective sides depending therefrom. These respective sides have lower portions carried by the plurality of trolley assemblies riding on the respective rails. 
     These and other objects of the present invention will become apparent from a reading of the following specification taken in conjunction with the enclosed drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1-5 illustrate, schematically, the teachings of the prior art and the disadvantages and deficiencies therein. 
     FIG. 1 is a schematic (pictorial) side elevation of a typical bridge using a stationary traffic shield—heretofore habitually resorted to in the prior art—to facilitate vehicular traffic flow during maintenance operations on a selected section along the length of the bridge. 
     FIG. 2 is a cross-sectional view thereof, taken along the lines  2 — 2  of FIG.  1  and drawn to an enlarged scale. 
     FIG. 3 corresponds substantially to FIG. 1, but shows the prior art stationary traffic shield being dismantled following completion of the maintenance on the respective lengthwise section of the bridge. 
     FIG. 4 corresponds substantially to FIG. 3, but shows the traffic shield being re-assembled on the next adjacent lengthwise section of the bridge. 
     FIG. 5 corresponds substantially to FIG. 4, but shows the traffic shield re-assembled and fixed in place to again resume flow of the vehicular traffic. 
     FIGS. 6-9 illustrate, schematically, the improvement of the present invention and its features and advantages. 
     FIG. 6 corresponds substantially to FIG. 1; however, the traffic shield is not fixed or stationary but, rather, constitutes a movable safety tunnel that may be moved along the length of the bridge as progressive sections of the bridge are being worked on and maintained. 
     FIG. 7 is a cross-sectional view thereof taken along the lines  7 — 7  of FIG. 6, drawn to an enlarged scale and corresponding substantially to FIG. 2, and showing the movable safety tunnel having a trolley system riding on rails replaceably mounted on top of the respective parapets at the sides of the roadway—the trolley system being selectively locked and unlocked on the rails—such that the safety tunnel is movable into the next adjacent section of the bridge. 
     FIG. 8 corresponds substantially to FIG. 6, but shows the safety tunnel being moved to the next adjacent section of the bridge. 
     FIG. 9 corresponds substantially to FIG. 8 but shows the safety tunnel locked in place on the next adjacent section of the bridge, thereby enabling the traffic flow to resume as the maintenance is performed on the next adjacent section of the bridge. 
     FIG. 10 is a side elevation of the movable tunnel MT, the bridge being shown schematically. 
     FIG. 11 is a portion of FIG. 10, drawn to an enlarged scale, and showing the construction of the sides of the movable tunnel. 
     FIG. 12 is an end view of the movable tunnel which cooperates with the roadway of the bridge, the remainder of the bridge being omitted for ease of illustration. 
     FIG. 13 is a portion of FIG. 12, drawn to an enlarged scale, and showing one of the trolley assemblies riding on a rail mounted on top of one of the parapets at each side of the roadway of the bridge. 
     FIG. 14 is an elevational view of a portion of one of the rails. 
     FIG. 15 is a top plan view thereof. 
     FIG. 16 is a bottom view thereof. 
     FIG. 17 is a plan view of one of the trolley assemblies within the overall trolley system. 
     FIG. 18 is an elevational view thereof. 
     FIG. 19 is a cross-sectional view thereof, taken along the lines  19 — 19  of FIG.  18  and drawn to an enlarged scale, and showing one of the trolley assemblies. 
     FIG. 20 is a further cross-sectional view thereof, taken along the lines  20 — 20  of FIG.  18  and drawn to an enlarged scale, and showing the J-bolts of the assembly in a locked position on the rail (the broken lines indicating the unlocked portion). 
     FIG. 21 is an elevational view of one of the J-bolts. 
     FIG. 22 is a front elevational view of one of the columns, the lower portion of which is secured to the respective upstanding gusset plates of the trolley assembly. 
     FIG. 23 is a side elevational view of the column of FIG.  22 . 
     FIG. 24 is an enlarged portion of the upper portion of the column shown in FIG.  23 . 
     FIG. 25 is a top plan view thereof, taken along the lines  25 — 25  of FIG.  24 . 
     FIG. 26 is a side elevation of an end portion of the trolley assembly of FIG. 18, drawn to an enlarged scale and detailed. 
     FIG. 27 is an end view thereof, taken along the lines  27 — 27  of FIG.  26 . 
     FIG. 28 is a side elevation of the other end of the trolley assembly of FIG. 18 and, again, enlarged in scale and detailed. 
     FIG. 29 is a detailed view thereof, taken along the lines  29 — 29  of FIG.  28 . 
     FIG. 30 is a bottom view of the roof panel. 
     FIG. 31 is a longitudinal section view thereof, taken along the lines  31 — 31  of FIG. 30 . 
     FIG. 32 is a detail view of one embodiment of the roof panel, drawn to an enlarged scale. 
     FIG. 33 is an end view of the one embodiment of the roof panel; the panel is provided with connection tubes that fit inside the respective columns. 
     FIG. 34 is a detail view of a second embodiment of the roof panel, drawn to an enlarged scale. 
     FIG. 35 is an end view of the second embodiment of the roof panel; and again, the panel is provided with connection tubes that fit inside the respective columns. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIGS. 1-5, the disadvantages and deficiencies of the prior art will become readily apparent. 
     In FIG. 1, the workers W are performing maintenance, repair and/or construction operations on a given length L of a bridge B. While this work is being performed, the traffic flow of the vehicles is accommodated by a conventional traffic shield T. 
     As shown in FIG. 2, the traffic shield T is an inverted U-shaped structure which cooperates with the deck or roadway  14  of the bridge B. 
     In the prior art, the respective length L of the bridge B (being worked on) is enclosed by a suitable tarp or cover C. This cover C is shown broken away in FIGS. 1 and 5, and is omitted in FIG. 4 for ease of illustration. The purpose of the cover C is to assure that the paint chips, the sand for sand-blasting or the steel balls used for shot-blasting, and any other dust and debris that is generated will be wholly confined within the cover C. A truck-mounted vacuum cleaner (not shown) continually removes all of the dust and debris; and where shot-blasting equipment is used, filters out the steel balls for subsequent reuse. Between the cover C and the bridge B, suitable catwalks and/or scaffolding (also not shown) are installed for facilitating the maintenance work and ready access for the workers. Again, all of this is well-known in the prior art; hence need not be detailed herein. 
     Of significance, however, and as shown schematically in FIGS. 3 and 4, once the maintenance work on the respective length L of the bridge B has been completed, the tunnel T must be completely dismantled or disassembled, taken to the next adjacent length L′ of the bridge B, and re-assembled therein as shown in FIG. 5 to resume the normal traffic flow. The tunnel T, once assembled and installed within the length L (or L′) of the bridge B, is stationary and fixed in place. It is not readily movable. Not only is the traffic flow interrupted for a substantial time period, but excessive construction costs are incurred. 
     With reference to FIGS. 6-9, the improved tunnel MT of the present invention is movable, not stationary, and this is the key feature of the invention. 
     The movable tunnel MT may be pre-fabricated in sections, taken to the bridge B and installed with use of a crane or other suitable equipment. Final assembly of the tunnel MT may take place on the bridge B. In a preferred embodiment, the tunnel MT may have length of around 200 feet. 
     The tunnel MT is movable along the entire length of the bridge (in progressive increments) as the maintenance operations are performed. For this purpose, the tunnel MT has a trolley system (hereinafter described in detail) which rides on specially-built rails on top of parapets on each side of the roadway. When a particular section of the bridge B is to be worked on, the trolley system is locked against movement on the rails; and when the work on that particular section of the bridge B has been completed, the locking mechanism is released, and the entire tunnel MT (being movable as shown in FIG. 8) is pushed or pulled by a fork-lift truck (or other suitable equipment) into the next adjacent, and possibly overlapping, position along the bridge B. Thereafter, and as shown in FIG. 9, the trolley system is again locked against movement of the tunnel MT along the length of the bridge B, so that the maintenance work can be performed on the next section L′ of the bridge B; and the process is repeated until the work on the entire bridge B has been completed. 
     The movable tunnel MT is, of course, moved in the direction in which the maintenance is being performed on the bridge B. 
     With reference to FIGS. 10-12, the movable tunnel MT is an inverted U-shaped structure including a roof assembly  10  and a pair of parallel side wall assemblies  11  depending therefrom. The roof assembly  10  includes a plurality of individual roof panels  12  connected to respective columns (hereinafter described) and each side assembly  11  includes a plurality of individual side panels  13  connected to respective columns (hereinafter described) thus providing a modular design for construction of the complete movable tunnel MT. Preferably, the roof panels  12  and the side panels  13  are corrugated steel panels, as shown, but it will be understood by those skilled in the art that any suitable panel, such as marine plywood, could be used if desired. 
     It will also be understood that the movable tunnel MT cooperates with an existing deck or roadway  14  of the bridge B to provide a complete enclosure for the traffic flow. 
     With reference to FIGS. 12-21, the bridge roadway  14  has respective barrier walls or parapets  15  at each side thereof, and a rail  16  is secured to the top of each parapet  15 . Each rail  16  is a closed tube (or box) which, in a preferred embodiment, is 4×4×¼ inches thick. Spaced-apart transverse flanges  17  are welded to the bottom of each rail  16 , and the flanges  17  extend laterally from the respective sides of the rail  16 , thereby assuring lateral stability of the rail  16  on the parapet  15 . These flanges  17  are spaced approximately four feet apart along the length of the rail  16 . A {fraction (13/16)} inch hole is drilled in each flange  17  (and in each bottom wall of the rail  16 ) along the center line of the rail  16 . A 3¼ inch access hole  18  is drilled in the top of the rail  16  along the center line of the respective transverse flange  17 . A suitable concrete anchor bolt  19  passes through each access hole  18  and anchors the rail  16  to the parapet  15 . 
     A trolley assembly  20  rides on each rail  16  (as shown more clearly in FIG.  20 ). This trolley assembly  20  has a wheel assembly  21  (see FIG. 19) rotatably journaled in sintered oil-impregnated bronze bearings  22  on a central axle or pin  23 . These bearings  22  are more desirable than ball-bearings for a grit-laden or shot-laden environment. The respective ends of the pin  23  are secured in a pair of downwardly-projecting spaced-apart channels  24  provided with stiffeners  25 . These channels  24  are part of a gusset assembly  26 . A plurality of gusset assemblies  26  are provided, being spaced approximately eight feet apart along the length of the trolley assembly  20 . 
     The wheel assembly  21 , preferably, consists of a section of a 6⅝ inch pipe  27  cut to a length of 4½ inches and welded between a pair of circular side plates  28  and  29 , respectively. The diameter of these circular side plates  28 ,  29  extends beyond the 6⅝ inch O.D. of the pipe  27 , such that the radially-extending portions of the circular side plates  28 ,  29  straddle the four-inch closed-channel rail  16 , thereby providing lateral stability of the trolley assembly  20  on the rail  16  (even if high winds are encountered). 
     Each gusset assembly  26  has a pair of spaced-apart upwardly-extending gusset plates  30 , and each of the gusset plates  30  is provided with a central transverse stiffener  31 . Each gusset plate  30  further has a pair of spaced-apart {fraction (15/16)} inch holes  32 , one on each side of the stiffener  31 . 
     A plurality of columns  33  are provided. Each column  33  comprises a rectangular tube  34  that is split on top and welded to a central plate  35 . A pair of angles  36  depend from the lower end of the column  33 , and the lower portion of each column  33  has a pair of spaced-apart {fraction (15/16)} inch holes  37 . These holes  37  on each column  33  align with the holes  32  on the gusset plates  30 , thereby facilitating the bolting of the column  33  to the gusset assemblies  26  (and hence to the trolley assembly  20  which rides on the rail  16 ). 
     The roof assembly  10  is adjustably mounted to the top portions of the respective columns  33 . The roof assembly  10  has a plurality of depending members  38  telescoped within the columns  33 , and each member  38  has a plurality of vertically spaced-apart holes  39  aligned with corresponding holes  40  within the top portions of the respective column  33  for securing the members  38  (and hence the roof assembly  10 ) to the columns  33 . The roof assembly  10  consists of a plurality of corrugated horizontal panels  12 , and the roof assembly  10  is raised or lowered on the columns  33  by suitable hydraulic jacks (not shown). This allows the roof assembly  10  to be lowered to clear the structural elements of the bridge B while rolling the movable tunnel MT into its next position along the bridge B. Once adjusted vertically, a drift pin (not shown) is inserted between the aligned holes  39  and  40 , respectively. 
     The trolley assembly  20  is locked against the rails  16 , so that the movable tunnel MT does not move while the work is being performed on the particular portion of the bridge B. More specifically, each gusset assembly  26  has a pair of J-bolts  41  carrying respective nuts  42 . Each J-bolt  41  may be loosened and then rotated approximately 180° on its axis (see FIG. 20) such that a right-angularly bent portion  43  of each J-bolt  41  is received between the bottom of each rail  16  and its respective parapet  15 . When the respective nuts  42  are tightened, the J-bolts  41  are secured against the rail  16  and the trolley assemblies  20  (and hence the movable tunnel MT) are locked against longitudinal movement along the bridge B. 
     Suitable side panels  13 , such as corrugated sheeting or marine plywood panels, are secured between the respective columns  33 , thereby completing the movable tunnel MT. This assures that no dust particles, shot blasting or sand blasting material or debris will enter into the movable tunnel MT, thereby protecting the traffic flow therein. 
     In the preferred embodiment of the present invention, the movable safety tunnel MT is one hundred and ninety-eight (198) feet long, and is divided into six (6) sections, each of which is thirty-three (33) feet long. Each section is raised by a crane and lifted in place. In one practical application, the bridge B is over water; and the respective sections of the safety tunnel MT are transported by a barge. One end of each section of the safety tunnel MT has a pair of tongues  44  (see FIG. 26) which cooperate with a pair of plates  45  (see FIG.  27 ). Holes  46  in the tongues  44  are aligned with holes  47  in the plates  45 , and a pin or bolt (not shown) is received in these aligned holes, thereby assembling the respective sections together to form the complete safety tunnel MT. 
     Moreover, in the practical application, the portion of bridge B being maintained is approximately eighteen hundred (1800) feet long. In that application, the rails  16  are constructed along approximately five hundred (500) feet at one end of that portion of the bridge B. When the maintenance work is completed on length L of the bridge B, the safety tunnel MT is moved to the remaining length of the rails  16  on the bridge B, and then the rails  16  are taken up in a “leapfrog” fashion, section by section, and re-installed ahead of the safety tunnel MT and so on until the maintenance work on the complete length of the bridge B has been completed. A forklift truck (or other suitable equipment) moves the safety tunnel MT into its next position. 
     Only one lane of the bridge B may be closed off to re-install the rail  16 . 
     All of the components and/or materials of the movable tunnel MT of the present invention are readily available on the market, and the assembly thereof is relatively quick and convenient. Moreover, it will be appreciated by those skilled in the art that the dimensions of the various components disclosed herein are not for purposes of limitation but, rather, for purposes of making a complete disclosure to facilitate a review of the present invention by one skilled in the art and a ready appreciation of the features and advantages of the invention. 
     Obviously, many modifications may be made without departing from the basic spirit of the present invention. Accordingly, it will be appreciated by those skilled in the art that within the scope of the appended claims, the invention may be practiced other than has been specifically described herein.