Use of k-spiral, bend, jog, and wiggle shapes in design of railroad track turnouts and crossovers

Abstract

Railroad track transition curves having shapes referred to as K_spirals, Bends, Jogs, and Wiggles are suitable for use in various situations where railroad track transition curves are needed and have good dynamic characteristics. Such shapes can be used for design of railroad track turnouts and crossovers. In order for such shapes to be incorporated into turnouts and crossovers, rail switch arrangements are provided that can accommodate the superelevation profiles on which the favorable dynamic characteristics of those shapes depend. Such shapes can be used for turnout and crossover design in conjunction with two mechanical switch arrangements that are themselves well known, namely the transfer table and stub switch arrangements, and with two switch arrangements that are variants of the commonly used movable point arrangement, namely an arrangement in which the through point rail is wide over its whole length and an arrangement using a through point rail of relatively conventional taper and width but one that is bowed downward between its point and the frog.

1 . A configuration for a curved path of a railroad track turnout comprising a combination of a defined superelevation as a function of distance along a turnout track and an inferred horizontal curvature as a function of distance along the turnout track such that for a vehicle traveling at a selected speed a component of gravitational acceleration in a plane of the track is approximately equal at any distance along the track to a component of centripetal acceleration in the plane of the track and wherein the curved path has a shape selected from the group of shapes consisting essentially of a K-spiral, a Bend, one half of a Jog, and part of a Wiggle.  
   
   
       2 . A railroad track turnout configuration including two railroad track turnouts, each having the railroad track turnout configuration according to  claim 1 , wherein the two track turnouts are connected to form a crossover between two adjacent railroad tracks.  
   
   
       3 . A railroad track turnout configuration according to  claim 2  wherein a crossing route that passes through the two turnouts has an overall geometrical shape at least approximating a Jog.  
   
   
       4 . A railroad track turnout configuration according to  claim 1  wherein the overall shape and superelevation of a path having horizontal curvature has an overall geometrical shape which at least approximates at least a part of the shape of a K_spiral.  
   
   
       5 . A railroad track turnout configuration according to  claim 1  wherein the overall shape and superelevation of a path having horizontal curvature has an overall geometrical shape which at least approximates at least a part of the shape of a Bend.  
   
   
       6 . A railroad track turnout configuration according to  claim 1  wherein the overall shape and superelevation of a path having horizontal curvature has an overall geometrical shape which at least approximates at least a part of the shape of a Jog.  
   
   
       7 . A railroad track turnout configuration according to  claim 1  wherein the overall shape and superelevation of a path having horizontal curvature has an overall geometrical shape which at least approximates at least a part of the shape of a Wiggle.  
   
   
       8 . A railroad track turnout configuration according to  claim 1  wherein a switching function is achieved together with a requisite superelevation by a transfer_table arrangement.  
   
   
       9 . A railroad track turnout configuration according to  claim 1  wherein a switching function is achieved together with a requisite superelevation by a stub_switch arrangement.  
   
   
       10 . A railroad track turnout configuration according to  claim 1  wherein a switching function is achieved together with a requisite superelevation by a wide_point arrangement.  
   
   
       11 . A railroad track turnout configuration according to  claim 1  wherein a switching function is achieved together with a requisite superelevation by a compromise_point arrangement.