WO2003018912A1

WO2003018912A1 - Method of making rail support assemblies

Info

Publication number: WO2003018912A1
Application number: PCT/GB2002/003899
Authority: WO
Inventors: Robin Wolfendale
Original assignee: Hyperlast Limited
Priority date: 2001-08-23
Filing date: 2002-08-23
Publication date: 2003-03-06
Also published as: GB0403692D0; GB2393750A

Abstract

A rail support assembly comprises a beam (12) with a channel (11). This receives a rail (10) clad with a sheath (15) and the channel outside the sheath is filled with a liner or infill. The upper edge of the sheath may be sloped either towards or away from the rail, and a cover such as (18) or (15) place over the rail and resting on the top edges of the sheath during moulding.

Description

METHOD OF MAKING RAIL SUPPORT ASSEMBLIES

This invention relates to rail support assembles.

In recent years, there has been considerable development of assembles for construction of railway track, both in mainline or 'country' track, and in tramlines or track intended for laying in urban streets, to meet demands both for noise reduction, and for economic improvements in the laying of new track, and replacement of worn or damaged track.

The path of development followed in noise reduction generally involves the seating of rails in pads of resilient material, and sheathing of rails, particularly noise producing parts such as central webs, with resilient layers or pads in various arrangements. Increasing modularity,. pursued to accelerate the operation of laying track has focussed upon the production of preassembled lengths of track which are transported to the site of work and laid by special track laying machines. These preassembled lengths usually feature concrete cross-ties or sleepers and are adapted to major track replacement programmes on mainline routes.

The resurgence of rapid transit, light rail and urban tram rail schemes has given rise to constructions wherein rails are mounted on support beams extending lengthwise of the rail, to embed in streets so that the rail is level with the street surface. A track form is also known which comprises a reinforced concrete slab cast with a pair of troughs in the rail positions in which the rails are fixed using a poured elastomeric material.

Thus the requirements for quiet running and modular construction converge, and a pre-coated embedded rail is known where a controlled thickness of elastomer is cast about a rail of conventional profile, and the assembly cast onto a concrete support.

l An improved version is known as a shelled embedded rail PENNY (WO 99/63160) describes such a rail mounting construction wherein a tram or mainline rail is received in a channel in a concrete bed or slab.

The channel is lined with a shell, which is keyed to the concrete by means of ribs on the shell, and a resilient fill within the shell holds the rail in place. A firm grip is achieved by providing pinch points by shaping the cross-section of the channel.

A simplified structure comprises a channel performed in the concrete bed or slab, lined with a resilient filler body but without the additional shell proposed by Penny. The rail is then inserted into the lined channel. Such mounting constructions are suitable for generally rectangular rails and reversible, or "bull-headed" waisted rails where the space adjacent the narrow central web is occupied by filler strips. A track module can be created by forming a continuous reinforced concrete slab with troughs at the rail positions in which the rail support assembly is post fixed by means of a grout. The prior constructions of embedded and sheathed rail modules are relatively complex in structure and in the method of their assembly or manufacture. For example, the shell structure can be complex and necessitate the use of spacers and other precautions while the elastomer body is being cast about the rail within the shell. Also the track modules created are generally large and massive, as they comprise the full width of the rail bed, incorporating as they do both rails and their immediate support, and such modules required heavy lifting equipment for transporting and laying of the track.

An object of the invention is to provide an improved method for making modular rail track assembly which can be carried out quickly and economically and yet produce an assembly which has the advantages of the shelled embedded rail, and which also can be assembled in modular units which are suitable for handling manually or with only light hoisting gear during track building.

According to the invention, a method for making a rail track assembly comprises a method of making a rail track assembly comprising using modular elements which incorporate a rail receiving channel into which is fixed rail support means. The method may comprise forming a sheath element for a rail comprising a trough-shaped elastomer pad, introducing the sheath element and the rail into the channel and casting or moulding method in the channel to thereby produce an assembly comprising said rail clad with said sheath element embedded in said track assembly. The method may comprise forming the member with a core extending longitudinally of the mould to form a rail-receiving channel, placing a rail support assembly over the core, and casting the beam about the core and within the moul, a trough shaped elastomeric pad being retained within the rail receiving channel formed in the beam after removal thereof from the mould. The method may improve forming a mould for casting a beam with a core extending longitudinally of the mould to form a shape corresponding to the desired rail receiving channel and casting the beam about the core within the mould.

The rail track assembly may be completed by fixing a rail plus rail support into the pre-formed rail receiving channel by means of cememtitious grout or other suitable material.

Alternatively, the core extending longitudinally of the mould may be shaped to receive a rail support assembly (pre-moulded trough shaped elastomeric pad) and the beam cast about this assembly of core and rail support so that the pad is retained within the beam after removal from the mould its inner surface forming a rail receiving channel. The rail may be clad with the trough shaped elastomeric pad before insertion of the rail into the rail receiving channel.

The rail track assembly may be completed by insertion of a rail into the already lined rail reciving channel. The rail may be of any configuration, but is preferably either a generally rectangular cross-sectioned member for mainline or

'country' tracks, or, of generally square cross section with a wheel flange receiving groove in the running surface of the rail, for tramways or other street railways.

In a preferred method, the body or sheath is pre-moulded and then temporarily bonded to the rail and the rail/sheath combination is subsequently handled as a unit. The thus clad rail is then fixed in the rail receiving channel of the modular support beam as described above, and the excess volume in a preformed channel filled with material to fix it in place such as a cementious grout or other suitable in-fill materials. Advantageously a cover cap is provided over the rail and extending partly down the side of the rail to rest on the upper edge of the body or sheath. This cover cap serves to protect the upper surface of the rail, which will form the running surface after installation. Further, the cover cap prevents in-filling of the volume adjacent the top of the rail when the in-fill is inserted and can then be removed to leave a cavity adjacent the upper side of the rail for insertion of a sealant.

In another advantageous feature, the upper surfaces of the cladding or sheath may be inclined downwardly away form the rail, and the lower edges of the cover cap provided with a matching slope, so that the weight of the cover cap on the upper surfaces of the sheath will tend to force the edges of the sheath against the sides of the rails, so that the sheath tends to be retained on the rail. The opposite slope is used when it is intended to install the resilient filler before the rail is inserted. This would be the case when the pre-assembled rail/sheath assembly needs to be replaced due to damage or wear. In this case a moulded sheath with opposite slope may be fitted into the cavity left by removal of the pre-assembled rail. The replacement rail can then be pushed into place more easily guided by the slope on the top of the sheath.

The elastomeric pad is preferably of a polyurethane elatomer, such as DYNATHANE (Trade Mark) supplied by Hyperlast Limited, but other material such as PNA elastomers or latex elastomers, possibly with a cork of other suitable filler may be used.

The elastomeric pad may be formed by moulding or extrusion.

The beam may be cast from reinforced concrete or from a polymer concrete (sand and aggregate with a synthetic resin binder) or polymer bonded stone.

The rail track assembly is preferably produced in modular units, which are capable of being handled manually or with only light lifting gear, say in sections each of 1 to 2 metres length although longer sections can be used. These may be assembled in a prepared rail bed, using gauge maintaining spacers if necessary , to form a railway or tramway.

A preferred method according to the invention, and preferred embodiments of rail track assembly according to the invention as made by the method according to the invention will now be described with reference to the accompanying drawings, wherein :- Figure 1 is a cross sectional view of a rail and rail support assembly according to the prior art;

Figure 2 is cross sectional view of a first embodiment of rail support assembly in accordance with this invention;

Figure 3 is a cross sectional view of a second embodiment; Figure 4a to 4f are sectional views illustrating stages in a method of making a rail track assembly in accordance with the invention;

Figure 5 is a sectional view of a tram rail assembly with a rail in place prior to filling in of the channel around the rail; Figure 6 is a sectional view of the completed rail assembly, and

Figures 7 and 8 are corresponding sectional views of a main line rail assembly. The prior art rail support assembly shown in Fig. 1 illustrates the most relevant known prior art constructions of rail support assembly, wherein a rail 10, which is shown may be of generally rectangular cross-section with rounded edges to the running surfaces, and Vestigial bulges towards each side. This shape is a consequence of eliminating features which are unnecessary, such as the foot flanges of currently standard flat bottomed rail, resulting in a slightly waisted reversible configuration reminiscent of the older standard 'bull-headed' rail without the strongly waisted centre sections of the latter. This produces a rail configuration which is close to a rectangular sectioned bar, and is easily producible by such techniques as drawing and forging and does not required the complex shaping of flat bottomed mainline or tramline rail.

The rail 10 is received in a channel 11 in the upper surface of a concrete slab or beam 12. The channel 1 1 is lined with a liner or shell 13. The shell or liner 13 is keyed with the concrete by means of ribs 14, and the volume between the rail 10 and the liner 14 is filled with an elastomeric layer 15 which is poured into the volume after location of the rail in channel 1 1, using spacers to separate the rail from the sides and floor of the channel. Seals such as 16 are used to close the top of the gaps on either side of the rail to provide a weatherproof seal. The concrete slabs 12 with the rails 10 in place, may be used in modular fashion to construct a rail or tram track, the slabs being provided in lengths which can be unloaded from a wagon and placed in situ, and adjusted for allignment by a few labourers possibly using a hoist or light crane. Such a known rail support assembly is known as a shelled embedded rail system.

Two embodiments of embedded rail system comprising rail support assembles made by the method of the present invention, are shown in Figures 2 and 3.

Figure 2 shows a main line or 'country railway' track assembly, having a rectangular rail 10 similar to that shown in connections with the prior art shelled embedded rail system of Figure 1. Figure 3 on the other hand shows a generally square rail 10, with a groove 17 in the running surface which is off set to one side, to provide a tramway or urban type rail.

Each of the assemblies shown in Figures 2 and 3 comprises a concrete beam 12 having a channel 1 1 formed in the upper face of the beam. A rail 10 rectangular in Figure 2 and square on Figure 3, as already mentioned above is received within the channel supported by a pre-moulded trough-shaped elastomeric pad 18 which has been cast into the concrete beam 12 in a process to be described below. The pad 18 conforms to the inner face of the channel 1 1 , which may have grooves such as 19 receiving beads on the rims of the pad 18. The rail 10 is seated in the trough shaped pad 12 in such a way as to be securely held, but capable of being removable for replacement. The upper part of the gap on each side of the rail is closed by sealing strips 20, which in the case of Figure 3 are ribbed to provide an anti-skid surface.

The concrete beams 12 in Figure 2 and 3 are of different shape, since as supports for mainline or 'country' track in Figure 2 the beams will be supported upon and partially nested in ballast. On the other hand as supports for tramway or 'town' track as in Figure 3, the beams will be fully recessed into the road surface with the upper surfaces of the beams 12 and rails level with the general street or road surface.

The beams 12 of Figure feature a step 21 spaced from the inner (wheel flange receiving) edge of the rail 10 which acts as an anti-derailing means in place of a guard rail, since if the wheels of a rail vehicle should leave the rail, they will tend to abut the step 21 and not allow the vehicle to leave the track. This is not necessary with tramway track as the flange receiving groove is already provided with a step which tends to limit derailing.

A preferred method of making a rail support assembly will now be described by way of example with reference to Figure 4a to Figure 4f. The method is shown in the manufacture of a rail support assembly generally according to Figure 3.

In Figure 4a, a generally trough shaped mould 40 with a lining of a polyurethane elastomer is prepared, and a longitudinally extending core 41, consisting of a pair of shaped side pieces 42, 43 and a central wedge spacer 44 is assemble in a groove extending along the centre line of the mould. Next, as shown in Figure 4b a trough shaped pre-moulded elastomeric pad 18 is fitter over the core 41. Then reinforcement rods 45 are arranged within the mould (Figure 4c) and concrete 46 poured into the mould 40 (Figure 4d).

After the concrete has set, the moulded reinforced concrete beam 12 is removed from the mould, and the core 41 disassembled and removed, so that the beam 12 is produced having the pad 18 lining the inner part of the channel 1 1 produced by the core. This is shown in Figure 4e. Finally as in Figure 4f, a rail 10 is located into the channel 1 1 and sealing strips 20 inserted to produce the assembly according to Figure 3. A railway or tramway track may be assembled by use of modular assembly units according to Figure 2 or Figure 3, with appropriate care in alignment and gauge spacing of the units. The units may be provided in sizes suitable for manual handling, and may be straight or curved to approximate radii. With sufficiently short sections in large radius curves, it may suffice for successive straight sections each set at an angle measurable in minutes of arc to be used.

Figures 5 and 6 show a generally rectangular cross-sectional tramway rail 10 . with a wheel flange groove 1 1 in the running surface, and bulges 12 at the base. In accordance with the present invention, a sheath 14 of resilient material is provided on the rail covering the base of the rail and extending about 60-70Ϋ to the top of the sides of the rail. The sheath 14 will normally be preformed and then placed onto the rail, and lightly bonded thereto but can be moulded in place on the rail.

In accordance with a preferred feature of the invention the running surface of the rail 10 is protected by a cap 15 in the form of a channel sectioned member having a base and side walls. The cap 15 placed over the rail after insertion of the rail into the sheath 14 and the rail 10 is then placed into a channel 16 in a concrete bed or support beam 17 with a clearance all around as shown in figure 1, spacing being maintained by sacrificial spacers of wood, plastics or metal, which are embedded in the channel; or other methods, such as suspension from a cross beam when a filler material 18 is introduced into the channel 16.

The cap 15 is kept in place over the rail whilst the filler material 18 is being poured into the channel 16 but is removed after the filler has set. This creates a space by each upper side of the rail, above the sidewall of the sheath 14 which can be filled with sealant 20 to prevent water and dirt from entering the sheath and chemically attacking the rail. As shown in the drawings, the lower edge 19 of each side web of the cap is bevelled so as to slope downwardly away from the rail, so that a lip is provided on the outer side of the side web. The upper edge of each side web of the sheath 14 is provided with a matching bevel or slope so that the side webs each provide a lip extending upwardly against the flank face of the rail, and any downward load acting on the cap 15, including its own weight, will tend to force the lip provided by each side web of the sheath 14 into contact with the respective flank of the rail, thereby improving sealing between the sheath and the rail. This is in distinction to the usual arrangement of the upper edge of the sheath, where the slope if present is in the opposite sense providing a lip in the outer face abutting the walls of the channel for example.

It is envisaged that a tramway or street rail could be formed from a standard mainline such as shown in Figure 2, with an inwardly spaced guard rail leaving a gap between the inner flange bearing edge of the main rail and the guard rail, and set in a matrix, so that a groove and inner rim arrangement similar to the groove in a standard street rail is produced.

The sheath 14 may be of a suitable resilient material, such as a suitable polyurethane composition. The cap 15 may be of a rigid or firm material, such as metal, rigid polyurethane or other synthetic material, or wood. The filling composition for filling the gaps between the sheath and the sides of the channel may be concrete, a resin bonded aggregate, or a synthetic material such as an appropriate polyurethane or polyurethane bonded material.

Figures 7 and 8 show corresponding views of a main line rail assembly, wherein corresponding features have been given the same references as in figures 1 and 2. The main differences are the shape of the rail, with no groove 1 1 being provided, and that the inner face of the rail is exposed by making the level of the beam 17 lower at the inner side and also the side wall of the sheath 14 is lower, and the inner limb of cap 15 is longer. This allows for the fact that the flanges fo railway vehicle wheels extend below the level of the top of the rail on the inner side of the rail.

Claims

1. A method of making a rail track assembly comprising using modular elements which incorporate a rail receiving channel into which is fixed rail support means.

2. A method of making a rail track assembly according to claim 1 comprising forming a sheath element for a rail comprising a trough-shaped elastomeric pad, introducing the sheath element and the rail into a channel, and casting or moulding material on the channel to thereby produce an assembly comprising said rail clad with said sheath element embedded in said rail track assembly.

3. A method according to claim 2 comprising forming a mould for casting a beam, with a core extending longitudinally of the mould to form a rail-receiving channel, placing a rail support assembly over the core, and casting the beam about the core and within the mould, the trough shaped elasomeric pad being retained within the beam after removal thereof from the mould.

4. A method according to claim 3 wherein the beam is cast from reinforced concrete or from a polymer concrete, or polymer bonded stone.

5. A method according to claim 2 wherein the rail is clad with the trough shaped elastomeric pad before insertion of the rail into the rail receiving channel.

6. A method according to claim 2 wherein the assembly is completed by insertion of the rail onto the already lined rail receiving channel.

7. A method according to claim 5 wherein the sheath is pre-moulded and then temporarily bonded to the rail and the thus clad rail then sealed in the bed or support beam and excess volume in the channel filled with material to fix it in place.

8. A method according to claim 7 wherein a cover cap is provided over the rail and extends partly down the sides of the rail to rest in the upper edges of the body or sheath.

9. A method according to claim 7 wherein the upper edges of the sheath are inclined downwardly away from the rail and the lower edges of the cap are provided with a corresponding slope.