Abstract:
An existing railway line is mounted to a fresh concrete sleeper by drilling a hole through a base plate which is attached to the line. A threaded sleeve with a large head is inserted into the hole from below and a threaded shank is passed through the base plate and into the hole from above and is then engaged with the sleeve.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to the installation of a railway sleeper particularly at a railway line turnout or crossing.  
         [0002]     At a turnout single railway lines are split into two. At a crossing a facility is provided whereby two lines cross each other. Due to the varying effective width over which the railway lines extend a need exists for railway sleepers of variable lengths.  
         [0003]     In a new turnout or crossing it is possible to prefabricate sleepers to the appropriate lengths. At an existing turnout which is to be refurbished it is necessary to fabricate sleepers to replace existing sleepers taking into account the geometrical requirements of the existing installation.  
         [0004]     Concrete sleepers are in widespread use in new installations and in refurbishing existing installations. As concrete sleepers are manufactured using moulds of precise dimensions under factory conditions it is not always economically feasible to cast a concrete sleeper, using customary techniques, to produce a product which can be substituted for an existing sleeper in an installed location.  
       SUMMARY OF INVENTION  
       [0005]     The invention provides a method of installing a railway sleeper which include the steps of marking an elongate cast cementitious member at a plurality of locations, forming a plurality of holes through the member, each hole being at a respective location, placing at least a first element of a respective fastener in each respective hole, positioning the member below a railway line and engaging a second element of the respective fastener, with the first element, thereby to secure the railway line to the member.  
         [0006]     The member may be marked at the plurality of locations by placing the member in a position, below the railway line, at which the member is to be secured to the railway line.  
         [0007]     The positions of the holes, which are formed in the member, may be determined by reference to holes in at least one base plate to which the railway line is attached. By using the method of the invention the base plate is attached to the sleeper and the railway line, which is secured to the base plate, is thereby attached to the sleeper.  
         [0008]     The holes in the member may be formed by drilling the member in situ.  
         [0009]     Each hole may be drilled from what in use is an upper side of the member to what in use is a lower side of the member.  
         [0010]     The first element may vary according to requirement but typically is a nut. The nut may be engaged with the member so that it does not protrude from a lower surface of the member. The nut may be fixed to the member in any appropriate way and for example may be adhesively secured to the member or grouted in position. Alternatively the nut may be mounted in a insulating holder such as a plastics sleeve or cup or the like which is frictionally or adhesively secured to the member.  
         [0011]     In a variation of the invention the first element of a fastener is inserted into a respective hole in the cementitious member, from a lower side and a second element is inserted into the hole, from an upper side and then engaged, preferably threadedly, with the first element.  
         [0012]     The first element may be a nut, with a head which bears on a surface of the lower side, and the second element may be an elongate bolt. An insulating sleeve or spacer may be used to prevent direct metal-to-metal contact between the fastener and a base plate to which the railway line is attached. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The invention is further described by way of examples with reference to the accompanying drawings in which:  
         [0014]      FIG. 1  schematically illustrates a turnout in which a plurality of sleepers according to the invention can be used;  
         [0015]      FIG. 2  is a plan view of a timber railway sleeper used in the turnout of  FIG. 1  which is to be replaced using the method of the invention;  
         [0016]      FIG. 3  is a plan view of a precast concrete sleeper;  
         [0017]      FIG. 4  shows a fastener for use in the invention;  
         [0018]      FIG. 5  illustrates the use of the fastener shown in  FIG. 4 ; and  
         [0019]      FIG. 6  shows a different type of fastener. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENT  
       [0020]      FIG. 1  of the accompanying drawings illustrates in plan a turnout  10  in a railway line which is of known construction. The turnout illustrates a pair of railway tracks  12  which split into two pairs of railway tracks  14  and  16  respectively which diverge from each other. The tracks are supported on a plurality of sleepers  18 . It can be seen that the sleepers are of variable lengths. Sleepers  18 A, which support only the tracks  12 ,  14  or  16 , have a conventional or standard length. Sleepers which serve both sets of tracks  14  and  16  are designated  18 B and are longer than the sleepers  18 A. The lengths of the sleepers vary significantly from one another.  
         [0021]     Sleepers, historically, have been made from timber. This has given rise to problems when existing timber sleepers have to be replaced for there is a sortage of suitable timber, which is a valuable natural resource. Although concrete sleepers can be fabricated to replace the existing wooden sleepers this can normally only be done at a substantial cost. A difficulty in this connection is that the tracks  12 ,  14  and  16  are already in place and the concrete sleepers must then be fabricated with fastening holes or formations so that they can directly be used with the tracks without any on-site adjustment being required.  
         [0022]      FIG. 2  illustrates a timber sleeper  18 B which is engaged with lines  14 A and  14 B respectively of the tracks  14 , and with lines  16 A and  16 B of the tracks  16 . Each line rests on a respective base plate  22  and is secured to the base plate using conventional rail clips or fasteners which are known in the art and which, for this reason, are not further described herein. Each base plate has four holes  26  and coach bolts or similar fasteners, not shown in detail, are passed through the holes and threaded into the timber sleeper  18 B to fix the base plates to the sleeper.  
         [0023]     The method of the invention is concerned, inter alia, with the replacement of a wooden sleeper  18 B of the type shown in  FIG. 2  installed, as has been indicated, in a turnout or crossing as depicted in  FIG. 1 .  
         [0024]      FIG. 3  illustrates an elongate cementitious member  30  of rectangular cross section which is cast under factory conditions using conventional techniques. The member has a length  32  which is chosen according to requirement and which may be one of a number of standardised lengths. The length  32  is generally equal to or slightly greater than the length of a selected sleeper  18 B shown in  FIG. 2 , which is to be replaced.  
         [0025]     The member  30 , which has a standard cross section, is prefabricated and is reinforced using conventional prestressing techniques.  
         [0026]     The member  30  is stored at an appropriate location and is drawn from stock, according to requirement, for use in refurbishing a rail turnout.  
         [0027]     When a turnout is to be upgraded measurements are taken on site of the existing sleeper arrangement. A precast member  30  which, as stated, is more or less the same length as the sleeper  18 B which is to be replaced, is drawn from stock. At the installation site the fasteners which secure the base plates  22  to the selected sleeper  18 B are loosened. The base plates are however kept engaged with the lines  14 A,  14 B,  16 A and  16 B.  
         [0028]     Once the sleeper  18 B has been loosened from the base plates it is withdrawn from its position below the lines and the concrete sleeper  30  is pushed into position below the lines. The member  30  may be cut so that it has the same length as the wooden sleeper  18 B using any appropriate technique, for example using a diamond-tip saw blade.  
         [0029]     When the member  30  is correctly positioned below the base plates it is clamped in position and holes  34 , see  FIG. 5 , are drilled through the member using the holes  26  in the base plates  22  as templates. Each hole is drilled through the member from what in use is its upper side  36  to its lower side  38 . Fasteners of the kind shown in  FIG. 4  are then used to fix the rails to the sleeper.  
         [0030]      FIG. 4  shows a fastener  80  with a first element  82  which comprises an internally threaded metallic sleeve  84  with an open mouth  86  and an enlarged hexagonal head  88 , and a second element  90  which comprises a shank  92  which is threaded over one end  94  and which has a hexagonal head  96 .  
         [0031]     An insulating sleeve  98  of a suitable plastics material is engaged with the shank  92 , abuts the head  96  and, when installed, acts on an upper surface  36  of a concrete sleeper member  30 , via a base plate  22  through the medium of washers  100 .  
         [0032]     The head  88  abuts the lower surface of the sleeper and thus can readily be accessed by a spanner (not shown).  
         [0033]     The bolts are tightened so that they are firmly engaged with the nuts and the base plates are thereby secured in position. The railway lines which at all times remain secured to the base plates are thereby secured to the member  30 .  
         [0034]     It is therefore possible to fix the railway line to the member  30 , via the intermediate base plate  22  directly, after the holes  34  have been drilled, in the manner shown, provided sufficient ballast underlying the member  30  has been cleared for the first element  82  to be inserted into the hole with the member  30  in situ.  
         [0035]     The insulating sleeve  98  prevents direct metal-to-metal contact between the head  96  and the shank  92  on the one hand, and the base plate  22  on the other hand. This preserves the integrity of communication signals which are propagated through wheels and other structure of tracked vehicles on the railway lines. If this insulating action is not required then a modified fastener  80 A of the type shown in  FIG. 6  can be used. This fastener has an enlarged shank region  92 A which effectively compensates for the removal of the insulating sleeve (i.e. increases the diameter of the shank accordingly). Another feature, which can be adopted for both fasteners, is the provision of friction enhancing formations such as splines or knurling  102  on the sleeve  84 , and protrusions  106  on an inner surface of the head  88 , to help the sleeve engage with the concrete sleeper so that, as the shank is tightened, there is a reduced tendency of the element  82  to rotate.  
         [0036]     Through the use of the method of the invention the respective members  30  are accurately drilled, on site, as required so that they can directly replace wooden or other sleepers which have to be refurbished. All that is necessary in this regard is to ensure that the precast members  30  are of suitable lengths so that they can be cut to size on site to match the tracks with which they are to be used.