Rail sleeper and ballast-free track structure

Abstract

According to one aspect of the invention there is provided a prefabricated rail sleeper [ 10 ] suitable for use in erecting a track structure [ 30 ]. The rail sleeper [ 10 ] comprises an elongate body portion [ 12 ] for supporting rails [ 14 ], the body portion [ 12 ] including a top surface [ 12,1 ], a bottom face [ 12.1 ] and at least two side faces [ 12.3 ], and terminating at least at one end thereof in a transition joint formation [ 16 ] dimensioned matingly to engage a complimentarily dimensioned transition joint formation [ 16 ] of an adjacent rail sleeper [ 10 ] in use so as to form a substantially continuous track structure. The sleeper [ 10 ] also includes a series of block formations [ 20 ], each of which is at least partially outwardly flared and extending beyond the side faces [ 12.3 ] of the body portion [ 12 ] so as to increase shear interlock of the sleeper [ 10 ] with the track bed to reduce longitudinal creep; as well as a series of transverse drainage ducts [ 26 ] extending underneath the rail sleeper [ 10 ] for allowing rainwater drainage between different side faces [ 12.3 ] of the body portion [ 12 ] and away from the rail sleeper. The invention extends to a ballast-free track structure [ 30 ] comprising at least two rail sleepers [ 10 ] according to the invention wherein the sleepers are located in spaced parallel orientation on a ballast-free track bed so as to define a centre drain [ 32 ] between the sleepers; and including a mesh [ 34 ] located between the sleepers [ 10 ] for reinforcing the centre drain [ 32].

1 . A prefabricated rail sleeper suitable for erecting a track structure, comprising: 
 an elongated body portion for supporting rails having a top face, a bottom face and at least two side faces, wherein the body portion terminates at least at one end in a transition joint formation dimensioned to matingly engage a complimentarily dimensioned transition joint formation of an adjacent rail sleeper.    
   
   
       2 - 42 . (canceled)  
   
   
       43 . The rail sleeper of  claim 1 , wherein the body portion terminates at both ends in a transition joint formation, wherein a series of rail sleepers are arranged in an end-to-end orientation on a track bed to form a substantially continuous track structure.  
   
   
       44 . The rail sleeper of  claim 1 , wherein at least two rail sleepers are arranged in an end-to-end orientation on a ballast-free track bed so that a transition joint space is defined between the transition joint formation of adjacent rail sleepers.  
   
   
       45 . The rail sleeper of  claim 1 , further comprising at least one block formation for supporting a rail, wherein the at least one block formation has an at least partially flared formation including a top surface, a bottom surface arranged to be substantially flush with the bottom face of the body portion, and at least two side surfaces.  
   
   
       46 . The rail sleeper of  claim 45 , wherein the at least two side surfaces of the block formation at least partially flare outwardly from the top surface towards the bottom surface and extend beyond the at least two side faces of the body portion of the rail sleeper.  
   
   
       47 . The rail sleeper of  claim 45 , further comprising a number of block formations spaced substantially equally along a length of the rail sleeper.  
   
   
       48 . The rail sleeper of  claim 45 , wherein the top surface of the block formation is dimensioned for receiving rail fasteners, wherein the top surface of the block formation is raised relative to the top face of the body portion forming a gap between a rail foot and the top face of the body portion.  
   
   
       49 . The rail sleeper of  claim 45 , further comprising at least one bore arranged proximate to the block formation and extending between the top and bottom faces of the body portion, wherein the at least one bore is dimensioned for receiving a material for underpinning the block formation and a rail foot.  
   
   
       50 . The rail sleeper of  claim 1 , further comprising at least one transverse drainage duct extending underneath the rail sleeper and defined by a box-out recess in the bottom face of the body portion, wherein the at least one transverse drainage duct allows a liquid to drain between different sides faces of the body portion and away from the rail sleeper.  
   
   
       51 . The rail sleeper of  claim 50 , further comprising a series of transverse drainage ducts that are longitudinally spaced along a length of the rail sleeper.  
   
   
       52 . The rail sleeper of  claim 1 , further comprising at least one longitudinal service duct located in and extending along a length of the body portion.  
   
   
       53 . The rail sleeper of  claim 45 , further comprising resilient pads arranged on the top surface of the block formation and dimensioned for receiving a rail foot, wherein the resilient pads at least partially protect the rail sleepers from exerted dynamic and impact loads.  
   
   
       54 . The rail sleeper of  claim 1 , wherein the rail sleeper is pre-cast from concrete selected from the group consisting of pre-stressed concrete, post-tensioned concrete, and conventionally reinforced concrete, wherein the rail sleeper is pre-cast in an upside down manner causing concrete at the top face of the sleeper to be more dense than concrete at the bottom face of the rail sleeper.  
   
   
       55 . The rail sleeper of  claim 54 , wherein the concrete is cured, wherein properties of wet concrete are modified by additives, wherein properties of set concrete are modified by impregnation.  
   
   
       56 . The rail sleeper of  claim 54 , wherein the concrete is augmented with fibers selected from the group consisting of polymeric fibers, natural fibers, and steel fibers to form fiber reinforced concrete.  
   
   
       57 . The rail sleeper of  claim 54 , wherein the concrete includes rubber particles.  
   
   
       58 . The rail sleeper of  claim 1 , wherein the rail sleeper is located on a ballast-free track bed during erection of the track structure.  
   
   
       59 . The rail sleeper of  claim 1 , wherein the rail sleeper is formed in varying lengths to accommodate track curves of different radii.  
   
   
       60 . A prefabricated rail sleeper for erecting a track structure, comprising: 
 an elongated body portion for supporting rails having a top face, a bottom face, and at least two side faces, wherein the elongated body portion has at least one drainage duct for facilitating drainage of liquid away from the rail sleeper.    
   
   
       61 . The rail sleeper of  claim 60 , wherein the at least one drainage duct is a transverse drainage duct extending underneath the rail sleeper, wherein the transverse drainage duct is defined by a box-out recess in the bottom face of the body portion.  
   
   
       62 . A prefabricated rail sleeper for erecting a track structure, comprising: 
 an elongated body portion for supporting rails having a top face, a bottom face and at least two side faces; and    at least one block formation dimensioned for at least partially accommodating a rail, wherein the block formation is at least partially flared.    
   
   
       63 . The rail sleeper of  claim 62 , wherein the block formation includes a top surface, a bottom surface arranged substantially flush with the bottom face of the body portion, and at least two side surfaces.  
   
   
       64 . The rail sleeper of  claim 63 , wherein the at least two side surfaces of the block formation at least partially flare outwardly from the top surface towards the bottom surface, wherein the side surfaces extend beyond the at least two side faces of the body portion.  
   
   
       65 . The rail sleeper of  claim 63 , wherein the top surface of the block formation is dimensioned for receiving rail fasteners, wherein the top surface of the block formation is raised relative to the top face of the body portion forming a gap between a rail foot and the top face of the body portion.  
   
   
       66 . The rail sleeper of  claim 62 , further comprising at least one bore arranged proximate to the block formation extending between the top and bottom faces of the body portion, wherein the at least one bore is dimensioned for receiving a material for underpinning the block formation and a rail foot.  
   
   
       67 . The rail sleeper of  claim 62 , further including a bore filled with a material extending vertically through the rail sleeper and into ground underneath for underpinning the rail sleeper.  
   
   
       68 . A ballast-free track structure for carrying rails of a railway track, comprising: 
 a series of rail sleepers each having an elongated body portion for supporting rails, wherein the body portion includes a top face, a bottom face, and at least two side faces, wherein the body portion terminates at least at one end in a transition joint formation dimensioned to matingly engage a complimentarily dimensioned transition joint formation of an adjacent rail sleeper, wherein the rail sleepers are located in an end-to-end orientation on a ballast-free track bed such that the transition joint formation of one rail sleeper matingly engages the transition joint formation of an adjacent rail sleeper forming a substantially continuous track structure.    
   
   
       69 . The ballast-free track structure of  claim 68 , wherein the transition joint formation between adjacent rail sleepers is secured by underpinning the transition joint formation with a method selected from the group consisting of using in-situ polymeric concrete, installing a jockey slab underneath the joint, and bolting connections.  
   
   
       70 . A ballast-free track structure for carrying rails of a railway track, comprising: 
 at least two rail sleepers having an elongated body portion for supporting rails, wherein the body portion includes a top face, a bottom face and at least two side faces, wherein the at least two rail sleepers are placed parallel to each other on a ballast-free track bed defining a center drain between the at least two rail sleepers; and    a mesh located between the at least two sleepers for reinforcing the center drain.    
   
   
       71 . The ballast-free track structure of  claim 70 , wherein the mesh is fixed to the body portion of at least one rail sleeper and extends from a side face forming a track slab.  
   
   
       72 . The ballast-free track structure of  claim 70 , wherein the mesh is constructed by series of weld meshes that are laced together once the at least two rail sleepers are laid on the track bed.  
   
   
       73 . The ballast-free track structure of  claim 70 , wherein the at least two rail sleepers are connected to each other using at least one cross tie extending between adjacent parallel rail sleepers.  
   
   
       74 . The ballast-free track structure of  claim 70 , wherein the track structure includes at least one resilient mat located between the bottom face of the body portion and the track bed, wherein the at least one resilient mat is composed of a material adapted to at least partially absorb loading between the at least two rail sleepers and hard surfaces.  
   
   
       75 . The ballast-free track structure of  claim 70 , further comprising at least one bore filled with a material extending vertically through the at least two rail sleepers and into ground underneath for underpinning the at least two rail sleepers.  
   
   
       76 . A method of laying a ballast-free track structure, comprising: 
 constructing a base formation;    fixing rail sleepers in spaced parallel orientation to form track panels;    laying the track panels in an end-to-end orientation on the base formation;    placing and fastening rails into position on the rail sleepers; and    adjusting vertical and horizontal alignment of the rail sleepers.    
   
   
       77 . The method of  claim 76 , wherein adjusting vertical alignment includes lifting and wedging the track panels to a correct height and packing a material underneath the rail sleepers.  
   
   
       78 . The method of  claim 76 , wherein adjusting horizontal alignment includes dragging the rail sleepers laterally.  
   
   
       79 . A method of manufacturing a concrete rail sleeper, comprising: 
 pre-casting the rail sleeper in a steel shutter in an upside down fashion so that a top face of the rail sleeper consists of the densest concrete; and    vibrating the steel shutter so that the top face of the rail sleeper consists of a maximum density.