Abstract:
A railroad wayside signal cantilever ( 10 ) including an arm ( 22 ) with a signal mounting apparatus ( 28 ) that provides a degree of horizontal movement of the signal ( 26 ) relative to the cantilever mast ( 12 ). The available range of locations for securing the signal on the arm is sufficiently broad to allow a single cantilever design to be used for a wide range of site-specific locations. An extendable catwalk railing ( 54 ) is provided to accommodate movement of the signal without creating an unsafe gap between the railing and the signal.

Description:
This application claims benefit of the May 6, 2005, filing date of U.S. provisional application No. 60/678,302, incorporated by reference herein. 

   FIELD OF THE INVENTION 
   This invention relates generally to the field of railroad wayside signals and more specifically to wayside signal cantilever structures. 
   BACKGROUND 
   A variety of structures are currently used to support railroad wayside signal indicators. Posts and pads are used to mount signals at the side of a rail line. Bridge structures are used to support signals above a rail line. Bridge structures include two mast/post structures disposed on opposite sides of a rail line, with an arm structure supported between the two masts at a height above the rail line. One or more signal devices are affixed to the arm structure at predetermined locations relative to the rails. 
   Cantilever structures are also used to support a wayside signal above a rail line. Cantilever structures advantageously require a footprint on only one side of the rail line. A wayside signal cantilever, such as for example a Model QNR available from Safetran Systems Corporation of Louisville, Ky., includes a single mast mounted next to the rail line and supporting an arm in cantilever fashion to extend over a rail line at a predetermined height. Signal devices are affixed to the arm structure at predetermined locations relative to the rails. Cantilever structures are available for rail lines consisting of one, two or three parallel tracks. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a wayside signal cantilever including adjustable signal mounting structures. 
       FIG. 2  is a side view of the cantilever of  FIG. 1 . 
       FIG. 3  is a top view of the cantilever of  FIG. 1 . 
       FIG. 4  is a perspective view of a signal and associated mounting apparatus of the cantilever of  FIG. 1 . 
       FIG. 5  is a partial side view of the signal and associated mounting apparatus of  FIG. 4 . 
       FIG. 6  is a top view of the mounting apparatus of  FIG. 4  with the signal removed. 
       FIG. 7  is a sectional view of the cantilever of  FIG. 1 . 
       FIG. 8  is a detail view of the handrail of the cantilever of  FIG. 1  showing an adjustable insert. 
       FIG. 9  is a side view of a signal mounting apparatus providing for a plurality of discrete signal positions. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Dimensional requirements for overhead wayside signals vary as a function of the number of tracks, the desired location of the signal relative to the track, the location of available space for the mast footprint relative to the tracks, and other railroad and application specific variables. As a result, each order issued by a railroad for the purchase of a wayside signal cantilever is treated as a unique project based upon its location, with each project requiring site-specific drawings and undergoing engineering and administrative review to ensure that the site-specific requirements are satisfied. 
   The present inventors have innovatively developed a railroad wayside signal cantilever structure that provides improved flexibility and potentially lower cost and faster delivery than prior art wayside signal cantilevers. The wayside signal cantilever of the present invention incorporates a signal mounting apparatus that provides a degree of adjustment in the location of the signal(s) on the arm. The inventors have found that it is possible to utilize a single cantilever design for a large majority of the wayside signal cantilevers for various U.S. railroad systems by providing a mechanism for adjustment of the signal location to any position within plus or minus six inches of a center position (one foot range of adjustment for the signal closest to the mast). The use of such a standardized yet adjustable design allows for on-site customization of the location of the signal(s) on the mast in response to site-specific requirements without the need for site-specific engineering prior to fabrication. 
   One embodiment of a railroad wayside signal cantilever  10  is illustrated in perspective view in  FIG. 1 , in side view in  FIG. 2 , and in top view in  FIG. 3 . In this embodiment, the mast  12  is constructed with four vertically oriented tubular columns  14  interconnected by bridgework  16  of cross-bracing members. Other mast designs may be utilized in other embodiments. A ladder  18  may be provided for operator access to a catwalk platform  20  that extends into the upper section of the mast. The mast  12  is secured to a foundation (not shown) in any manner known in the art. The arm  22  of the cantilever  10  of  FIG. 1  is formed of a box frame structure providing two levels of catwalks  24  for access to two levels of signals  26 . Other embodiments may include only a single level. 
   The signals  26  illustrated in  FIG. 1  are standard three-lamp color light assemblies such as the Model CLS-20R supplied by Safetran Systems Corporation. Other types of signals may be used in other applications. The signals  26  are mounted to the arm  22  with an adjustable mounting apparatus  28  that allows the signal  26  to be secured to the arm  22  within a range of positions in a horizontal direction relative to the mast  12 . The illustrated embodiment of an adjustable mounting apparatus  28  is best appreciated by viewing  FIGS. 4-7 .  FIG. 4  is a perspective view of the mounting of a representative signal  26  of the cantilever  10  of  FIG. 1 .  FIG. 5  is a side view of the signal mount pedestal  30  used for mounting of the signal  26  of  FIG. 4 .  FIG. 6  is a top view of the pedestal  30  of  FIG. 5  with the signal removed to better illustrate aspects of the pedestal  30 .  FIG. 7  is a sectional view through the arm  22  of the cantilever  10  of  FIG. 1  as seen at section  7 - 7  of  FIG. 2 . 
   The signal  26  includes a lamp housing  32  and a base assembly  34 . The adjustable mounting apparatus  28  of this embodiment of the present invention includes a sleeve  36  attached to a bottom of the signal base assembly  34  for receiving a vertically extending portion  38  of pedestal  30 . The pedestal  30  further includes a mounting plate  40  attached to the vertically extending portion  38  and adapted for adjustable attachment to the arm structure  22  via two U-bolt assemblies  42  including respective U-bolts and associated nuts and optionally washers. The U-bolts extend around opposed sides of a tubular member  44  of the arm  22  and extend upward through arcuate slots  46  in the pedestal mounting plate  40 . When the U-bolt assemblies  42  are tightened, the signal  26  is affixed into the selected position on the arm  22  relative to the mast  12 . However, when the U-bolt assemblies  42  are loosened, the signal  26  may be moved horizontally across a range of positions relative to the mast  12  as the U-bolts are slid along the tubular member  44 . Appropriate openings/slots are provided through the catwalk decking  24  as necessary to accommodate the movement of the U-bolts. The arcuate slot  46  in the pedestal mounting plate  40  allows the pedestal  30  to be rotated as it is moved horizontally in order to facilitate alignment of the pedestal  30  with the attached electrical cable conduit  48 . Once the pedestal  30  is affixed into a desired position by tightening the U-bolt assemblies  42 , the sleeve  36  may be rotated about the upwardly extending portion  38  of the pedestal  30  to accomplish alignment with the cable conduit  48  prior to tightening the plurality of setscrews  50  provided for securing the angular position of the sleeve  36 /signal  26  relative to the upwardly extending portion  38 . The standard prior art signal assembly also provides a degree of angular rotation and vertical tilt of the lamp housing on its base assembly  34 . 
   In one embodiment the range of horizontal motion of each signal  26  is one foot; i.e. ±six inches from a nominal position on the arm  22 . Thus, the position of each signal  26  can be adjusted horizontally along the arm  22  relative to the location of the mast  12  by one foot, such as to accommodate the desire of one railroad to place the signal  26  above a position midway between the two rails of a track  52  and the desire of another railroad to place the signal off-center of the track  52 . The spacing between two adjacent signals  26  in the horizontal direction is thus adjustable by up to two feet with the signals at their respective extreme positions, thereby accommodating a range of distances between adjacent parallel tracks  52 . Other embodiments may provide greater or lesser ranges of horizontal adjustment, with the range of adjustment for each signal  26  not necessarily being the same as that of the others. For example, a first signal  26 ′ for a first track  52  most adjacent the mast  12  may have a range of motion of ±1 foot, with a second signal  26 ″ for a second track  52 ″ farther away from the mast  12  having a range of motion of ±2 feet in order to allow the second signal  26 ″ to be adjusted to a position ±1 foot from a nominal distance from the first signal  26 ′ no matter where in its range the first signal  26 ′ is positioned. Similarly, a third signal even farther away from the mast  12  (not illustrated) may be provided with an even greater range of motion in order to accommodate the variable positions of both the first signal  26 ′ and the second signal  26 ″. 
   The arm of the cantilever of  FIG. 1  is provided with railings  54  along the catwalks  20  for personnel safety. The signals  26  are positioned within respective openings  56  in the railings  54  in order not to obscure the visibility of the signal  26  from a passing train. The railing  54  adjacent the respective signals  26  may be provided with an adjustable insert  58 , such as illustrated in  FIG. 8 , in order to selectably extend the railing  54  to at least partially close the opening  56  when the signal  26  is secured at a selected location. Once the signal  26  is affixed into the desired position, the railing insert  58  is slid horizontally to a desired position. The insert  58  is then secured at that position such as with field-installed fasteners  60 . Other embodiments of an adjustable insert may include a folding accordion section or a rolling member to accommodate movement of the signal  26  while maintaining the safety of the railing  54 . 
   A cantilever  10  incorporating the present invention may be designed to comply with all relevant standards of design and construction; for example those promulgated by The American Railway Engineering and Maintenance of Way Association (AREMA) and/or the American Association of State Highway and Transportation Officials (AASHTO). Known materials and procedures may be used for the engineering, manufacturing, erection and maintenance of a cantilever embodying the invention. The use of a standardized cantilever  10  providing a range of available horizontal positions for the signals  26  may provide a savings of 20-40 man-hours in the processing of a purchase order for a cantilever for a particular site and may preclude the need for site-specific drawings. Furthermore, should the requirements for a particular location change, such as a change by a railroad in the desired location of the signals  26  relative to the tracks  52 , such a change may be accommodated without the replacement of or major modification to the installed cantilever  10 . 
   One skilled in the art will appreciate that other embodiments of the invention are possible, and that the embodiments illustrated and discussed herein are provided by way of example and are not meant to be limiting. For example, many other forms of attachment providing a plurality of discrete positions and/or a continuously variable range of positions for the signal  26  may be envisioned. As illustrated in  FIG. 9 , discrete positions may be provided by a plurality of holes  62  or notches to which a signal pedestal  30  may be inserted/secured. Alternatively, continuously variable positions may be provided along a rail or channel along which a signal mount may be moved. Such a signal mount may be secured to the rail or channel or separately to another arm structure via clamps, bolts, adhesives and/or any known type of fastener. The present invention may be embodied in cantilevers for use over one, two or three parallel tracks  52 , and having single or multiple vertical levels of signals  26  and catwalks  20 . The invention may further be embodied in a signal adjustably attached to an arm extending over a track regardless of whether the arm is supported in cantilever fashion, in bridge fashion or otherwise.