Patent Publication Number: US-8973195-B2

Title: Pipeline crossing bridge

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of and claims the benefit under 35 U.S.C. §120 of U.S. application Ser. No. 13/223,235, filed Aug. 31, 2011, which is incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     This document relates to pipeline crossing bridges. 
     BACKGROUND 
     Bridges or roads are used to cross pipelines. 
     SUMMARY 
     A pipeline crossing bridge comprising first and second ground contacting pads spaced apart from one another; plural ribs with lateral stabilizing elements between adjacent ribs of the plural ribs, each rib of the plural ribs being supported on both the first and second ground contacting pads and the ribs collectively forming an arch extending between the first and second ground contacting pads; and an upper crossing surface supported by the plural ribs. 
     These and other aspects of the device and method are set out in the claims, which are incorporated here by reference. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Embodiments will now be described with reference to the figures, in which like reference characters denote like elements, by way of example, and in which: 
         FIG. 1  is a perspective view of the top of a pipeline crossing bridge with the apron removed. 
         FIG. 2  is a perspective view of the top of the pipeline crossing bridge of  FIG. 1  with the apron in place. 
         FIG. 3  is a perspective view of the bottom of the pipeline crossing bridge of  FIG. 1  with the lower apron removed. 
         FIG. 4  is a perspective view of the bottom of the pipeline crossing bridge of  FIG. 1  with the lower apron in place. 
         FIG. 5  is a top plan view of the pipeline crossing bridge of  FIG. 1  in position over a buried pipeline. 
         FIG. 6  is a side elevation view of the pipeline crossing bridge of  FIG. 1 . 
         FIG. 7  is a top plan view illustrating the lateral interconnection of adjacent mats, with the portion of the male member that is inserted within the female member of the adjacent mat shown in dashed lines. The support tubes that form the female member within the adjacent mat are also shown in dashed lines. 
     
    
    
     DETAILED DESCRIPTION 
     Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims. 
     Pipelines are used across North America and the rest of the world to transport fluids such as petroleum products a distance from source to sink. Pipelines may be buried underneath, laid upon, or supported in a raised position above terrain. Because of the distances travelled by such pipelines, and other factors, it is often necessary for a road or passage to cross a pipeline. For raised pipelines and pipelines lying on the ground, it may be possible to provide a road overtop of the pipeline, for example using a bridge. In some cases, the road may be provided underneath the pipeline. 
     For buried pipelines, the crossing passes over the pipeline, for example directly or indirectly above fill material above the pipeline. Regulations may determine the minimum depth of fill required between the pipeline and the road in some cases. Regardless, vibration and compression from multiple crossings over time may lead to damage and eventual failure of the buried pipeline. In some cases a thick layer of clay or other dampening material may be provided above the fill material. However, such layers may be expensive to construct, and may still transfer vibrational and compressional energy to the pipeline, ultimately leading to pipeline damage. 
     Referring to  FIGS. 1-6 , a pipeline crossing bridge  10  is provided comprising first and second ground contacting pads  12  and  14 , respectively ( FIGS. 1 ,  2 ,  4 , and  6 ), plural ribs  16  ( FIGS. 1 and 3 ), and an upper crossing surface, such as an apron  18  ( FIGS. 2 ,  4 ,  5 , and  6 ). The first and second ground contacting pads  12 ,  14 , are spaced apart from one another, and may be planar in shape to transfer load across a sufficiently wide ground area. 
     The plural ribs  16  have lateral stabilizing elements  20 , such as one or more truss alignment bars  22  ( FIGS. 1 and 3 ), between adjacent ribs  16  of the plural ribs  16 . Elements  20  may extend between two or more of the plural ribs  16 . In the example shown, the truss alignment bar  22  spans all of the plural ribs  16 . Other components such as support tubes  24  may form lateral stabilizing elements  20 , for example by passing laterally through the entire set of plural ribs  16  for strength. Lateral stabilizing elements  20  prevent plural ribs  16  from folding under loading during use. Ribs  16  and stabilizing elements  20  may collectively form a skeleton or frame  21 , which may include other elements such as end plates  23  and side plates  25 , which may have the same shape as ribs  16 . 
     Each rib  16  of the plural ribs  16  is supported on both the first and second ground contacting pads  12 ,  14 . Ribs  16  may be spaced a suitable distance apart, for example one foot or less apart. Ribs  16  may run parallel to one another in the longitudinal direction as shown. In the example shown, pads  12  and  14 , which each may include one or more feet (not shown), are provided by support plates  26 ,  28 , respectively, connected to the plural longitudinal ribs  16 . Pads  12  and  14  may be positioned on a foundation (not shown) or on a ground surface  57  ( FIG. 6 ). The ribs  16  collectively form an arch  30  extending between the first and second ground contacting pads  12 ,  14 . The bridge  10  may have an arcuate middle portion  32  as shown that in use is raised above ground  34  that is desired to be crossed, such as ground  34  that is directly above a buried pipeline  36  ( FIG. 6 ). 
     The throat or arch  30 , which may be segmental as shown, may be wider than a diameter  51  of the pipeline  36  as shown ( FIG. 6 ). A segmental arch may be used over a semi-circular arch to reduce the maximum vertical height of bridge  10  while increasing the arch  30  span distance between the pads  12 ,  14 . By positioning bridge  10  over pipeline  36  so that the arcuate middle portion  32  is spaced above the ground  34 , bridge loading is transferred away from ground  34  directly above the pipeline  36 , thus reducing or eliminating damage to pipeline  36  that may otherwise occur over multiple crossings. In addition, arcuate middle portion  32  provides a convenient location for bridge  10  to be gripped and lifted during loading and unloading with suitable loading equipment such as a backhoe, crane, loader, or excavator. 
     The upper crossing surface or apron  18  ( FIGS. 2 ,  3 ,  4 ,  5 , and  6 ) may be positioned at least partially over the ribs  16  and is supported directly or indirectly by the plural ribs  16 . Lateral supports such as cross beams  39  ( FIGS. 1 and 3 ) may be positioned between ribs  16  and apron  18 . The combination of ribs  16  with lateral stabilizer elements  20  may be easier to manufacture and more resistant to folding under loading than the longitudinal corrugations (not shown) used in existing bridges. The apron  18  may be adapted to increase traction, for example by use of one or more traction bars  38 . Other suitable methods may be used to increase traction, for example using a textured or divoted upper surface (not shown). 
     A lower apron  40  ( FIGS. 1 ,  2 ,  4 , and  6 ) may be secured at least partially under the plural ribs  16 , for example under the ribs  16 , over the arch  30  and between the ground contacting pads  12 ,  14 . In some cases, pipeline crossing bridge  10  is entirely enclosed to prevent unwanted incursion into the bridge interior by dirt, contaminants, animals, plants, or other undesired elements. In other cases, bridge  10  may have plural holes  42  ( FIGS. 2 and 5 ) in apron  18  to allow air pressure equalization during loading, reduce bridge weight, allow evaporation of standing water or fluids within bridge  10 , and increase traction on apron  18 . 
     In the oil and gas industry, it is sometimes necessary to provide ground cover mats with sufficient strength to support heavy equipment and transport trucks over wet or disturbed ground. Oil field exploration and drilling operations are often undertaken in geographic areas that are, in their natural state, inaccessible to vehicles and equipment necessary for such exploration. These areas include swamps, marshlands, riverbeds, snow covered regions, and areas with soft or sandy soil. In order to explore for oil in such areas, it is necessary to locate heavy drilling rigs, vehicles and other equipment for some period of time on or adjacent to the location where the well is to be drilled. In order to transport this heavy equipment to the site and to support the equipment at the site, the industry has used for many years temporary roads leading to and from the site and flooring systems or pads at the particular site. 
     Existing flooring systems may involve a series of prefabricated mats. Mats are currently used for temporary road and access track in many other industries as well. Such mats may be generally used as alternatives to asphalt and concrete road paving, or for temporary storage pads for supplies and equipment. In contrast with traditional surfaces made with asphalt, gravel, or concrete, temporary road mats may cause less of a negative environmental impact, may be quicker and easier to set up, and may be easier to obtain required building permits for. 
     Referring to  FIG. 6 , bridge  10  may form part of a ground cover mat system (not shown). For example, bridge  10  may interlock longitudinally with one or more ground cover mats (not shown) to form a temporary roadway for rig equipment. In other embodiments, bridge  10  may be used as a standalone unit. Apron  18  may have a smooth and continuous tapered or arcuate shape as shown across the entire longitudinal length of the apron  18 , terminating at opposed ramp ends  41 . Ramp ends  41  may be sloped toward the ground or may terminate at an end height  43  sufficiently low to allow vehicular traffic to drive onto the apron  18  from the adjacent ground  57  or from an adjacent mat (not shown). In one example, the end height  43  may be five inches or less off the ground, thus lower than or equal to a standard curb height. The apron  18  may be designed to reduce or minimize disturbance to vehicular traffic over mat  10 , for example, by ensuring that apron  18  has a maximum slope of  20  degrees or less relative to ground level. 
     Bridge  10  may be formed as an arcuate mat as shown. A mat is understood to have a relatively constant vertical thickness, for example within 0-10 inches deviation from a mean vertical thickness, along the longitudinal length of the mat. Mat form allows bridge  10  to be effectively vertically stacked for example on a trailer bed, rail bed or other suitable cargo bed. After unloading, bridge  10  may be positioned directly upon ground surface  57  without burying bridge  10  fully or partially with fill ( FIG. 6 ). In some cases a radius of curvature  46  of the apron  18  is larger than a radius of curvature  48  of the arch  30 , for example so that a minimum vertical arch height  49  is present at the longitudinal center of the arch  30  as shown. The apron  18  may thus have a shallower slope than the arch  30 , thus reducing disturbance to traffic passing over bridge  10  while ensuring sufficient vertical spacing from ground  34  under arch  30 . If the arch  30  or apron  18  shapes have a degree of eccentricity, then the average radii of curvature should be used. 
     Referring to  FIG. 7 , the bridge  10  may be separable into two or more longitudinal portions  50 A,  50 B that interlock together with lateral alignment elements  52 ,  54  in the longitudinal portions  50 A,  50 B, respectively. In the example shown, alignment elements  52  are male members  53  that extend laterally into female members  55  such as support tubes  24 . Referring to  FIGS. 2 and 5 , cutouts  56  may be provided in apron  18  to allow a user vertical access to holes  58  for securing male members  53  and thus portions  50 A,  50 B together in place with screws or bolts (not shown) for example. 
     By providing bridge  10  in two or more separable longitudinal portions  50 A and  50 B, a bridge of a suitable width wider than a single longitudinal portion  50  may be conveniently assembled on site but transported to the site in separate, narrower, pieces. In addition, in some embodiments longitudinal portions  50 A,  50 B, or bridge  10  may be provided with a lateral width  60  ( FIG. 5 ) sufficiently narrow, for example twelve feet six inches or less, so as to allow horizontal transportation, for example on a truck bed (not shown), without the use of a pilot vehicle, thus saving on transportation costs. Widths of eight feet or less may also be used. 
     Although described above for use in spanning buried pipelines, in some cases bridge  10  may be used to span a gap defined by a river, gulley, or other uneven terrain to provide safe travel by heavy duty equipment or vehicles over the gap. Other natural or manmade formations such as above ground pipelines or partially buried drainage culverts may be spanned by bridge  10 . In some cases, the upper crossing surface may be planar, for example horizontally planar. 
     Bridge  10  may be rated to support loads of 60,000 pounds or more. In some embodiments bridge  10  is adapted to facilitate the passage of heavy duty equipment and vehicles over wet or disturbed ground. All dimensions are exemplary and other dimensions may be used, for example dimensions greater or smaller than the exemplary dimensional ranges provided. In addition, the use of directional language such as vertical and horizontal in this document illustrate directions that are relative to a ground surface  57  ( FIG. 6 ) that bridge  10  is placed upon. Although not illustrated in the Figures, supports that are angled relative to the longitudinal, vertical, and lateral directions may be used in the construction of bridge  10 .