WO2003012203A2

WO2003012203A2 - Rail arrangement

Info

Publication number: WO2003012203A2
Application number: PCT/GB2002/003582
Authority: WO
Inventors: Charles Penny; Barnaby Temple; Robin Wolfendale; Christopher J. C. Jones
Original assignee: Balfour Beatty Plc
Priority date: 2001-08-02
Filing date: 2002-08-02
Publication date: 2003-02-13
Also published as: WO2003012203A3; US20040245353A1; EP1436462A2

Abstract

One aspect of the invention provides a rail arrangement in which a rail is releasably supported in an inner shell, and the inner shell and rail are received within an outer shell. This provides flexibility in that the design of the inner shell can be varied to provide different relative positioning of the rail with respect to the outer shell. Thus, the inner shell can be used to take account of sinking of the outer shell, which is typically cast into the rail foundations.

Description

RAIL ARRANGEMENT

This invention relates to rail arrangements for a railway or tramway system.

A conventional rail essentially comprises an I-beam, having a head, a narrow web and a base. The rails are supported at regular intervals by the sleepers, using clips which bear down upon the wide base of the rail. The rail spans the spacing between sleepers, and the I-beam structure provides the required vertical strength of the rail across these spans.

Figure 1 shows an alternative rail design which has been proposed. The rail 20 is held in a shell 22 set in a bed or slab 24 of concrete. The shell 22 has an inner profile of an open channel to receive the rail 20 whilst also clamping the rail 20 in place. A resilient filler 26 is provided between the shell 22 and the rail 20.

The rail cross section comprises a head portion 20A and a supporting portion 20B. In the example shown in Figure 1 , the top of the supporting portion 20B has a pinched part 28. To insert the rail 20 into the shell 22, the wider lower part of the supporting portion 20B has to pass through the pinched region of the fill 26, so that the rail must effectively be sprung into the shell with a snap-action fit.

Despite this pinched part 28 of the rail cross section, the head portion 20A and the supporting portion 20B have substantially the same width. The only differences in width are provided to enable the snap-action fitting of the rail into the shell as described above, and not to provide the conventional I-beam cross section.

The bed or slab 24 is lower on one side of the rail than on the other side, to allow the passage of the flange of a wheel of the railed vehicle. However, the shell 22 provides support for as much as possible of the height of the rail 20 on both sides of the rail. In particular, the shell 22 provides support for at least part of the head portion 20A on both sides of the rail, and over the entire height of the supporting portion 20B on both sides. The rail design of Figure 1 is described in greater detail in WO 99/63160. The shell 22 defines a continuous supporting structure for the rail 20, rather than the discontinuous sleeper arrangement of the more conventional rail system.

There are a number of issues surrounding the use of a substantially rectangular section rail. The rail has a lower second moment of area (for a given weight of steel per unit length) than an I-beam rail, so that an increased volume of steel is required for the same structural stiffness. To some extent, this issue is resolved because the rail is supported along its full length. However, it is still desirable to use material most efficiently.

Another issue is the settlement of the foundations on which the rail is mounted, and the consequent lowering of the rail, which may render the surface of the rail uneven. The same issue arises if the rail wears outside of the required alignment tolerances. In the system of Figure 1, the shell is concreted into the slab and can not therefore be moved, so that no adjustment of the rail position is possible unless the slab itself is raised or the fill (which is a supporting pad) is changed and the thickness is increased. However, this adjustment is limited.

A further issue is that the arrangement of Figure 1 has different heights on each side of the rail, making the arrangement unsuitable for use as a tram rail arrangement or for switches and crossings.

According to a first aspect of the invention, there is provided a rail arrangement comprising: a rail; a resilient layer around at least the base of the rail; and an inner shell for receiving the rail and the resilient layer, and having an inner profile corresponding to the outer shape of the resilient layer, wherein the inner shell and rail are received within an outer shell.

In this arrangement, the "inner shell" (which is the part which retains the rail in place) is received in an outer shell. The inner shape of the "inner shell" is thus designed to cooperate with the rail, and the outer shape is designed to cooperate with the "outer shell". This provides flexibility in that the design of the inner shell can be varied to provide different relative positioning of the rail with respect to the outer shell. Thus, the inner shell can be used to take account of sinking or heave of the outer shell, which is typically cast into the supporting foundations which may be subject to sinking or heaving (rising).

A resilient or conforming layer may be provided outside the inner shell.

Preferably, the inner shell and rail are removably received within the outer shell, so that at least a portion of the inner shells can be changed in shape to correct for wear or sinkage or heave. The inner shell may for example be formed from pre-cast concrete or steel.

The inner shell may be heavier than the resilient layer, and it may then have sufficient mass to act as a mass damping component. For mass damping, a stiff resilient layer is required between the rail and the mass damping component, with a further (preferably softer) resilient layer between the mass damping component and the support structure (namely the outer shell). Therefore, for using the inner shell as a mass damping component, a resilient or conforming layer is also provided outside the inner shell. Thus, the arrangement can combine benefits of adjustability with mass damping capability.

The inner shell can be made to enable a non-rectangular rail to be fitted into a rectangular outer shell. For example, an I-beam rail may be used, and the inner shell can have an inner profile corresponding to the outer shape of the rail and a substantially rectangular outer shape. The resilient layer around the rail takes up tolerance differences between the rail and the inner shell. The outer shape is designed for cooperation with the outer shell, optionally through the additional resilient layer. The inner shell may have a two-piece cross section, each piece comprising a lateral portion, so that these pieces may be assembled around the I-beam rail. This provides a more efficient use of metal in the rail, but still enables the push fit system to be implemented. The inner shell may, however, be one-piece or may be formed in more than two pieces. According to a second aspect of the invention, there is provided a rail arrangement comprising: a rail; a resilient layer around at least the base of the rail; and a shell for receiving the rail and the resilient layer around the rail, wherein the rail has a base, a head and a central flange region, and wherein filler portions are provided one each side of the flange region, such that the outer shape of the rail and the filler portions is substantially rectangular, and wherein at least one of the filler portions comprises a first mouldable material and embedded mass damping portions of a second material, which is more dense than the first material.

A conforming layer is preferably provided between the filler portions and the rail to allow for tolerance differences.

This arrangement also enables an I-beam rail to be used within the push fit system, and uses the space on each side of the rail flange to accommodate mass damping components.

A third aspect of the invention provides an alternative mass damping solution, and provides a rail arrangement comprising: a rail; a mass damping component beneath the rail and having a width substantially equal to the width of the base of the rail; a resilient layer around the rail and the mass damping component; and a shell for receiving the rail and the mass damping component.

Preferably, a resilient .member is positioned between the rail and the mass damping component, for transferring vibrations from the rail to the mass damping component. This arrangement provides mass damping without increasing the width of the rail assembly. The rail preferably has a substantially rectangular cross section.

According to a fourth aspect of the invention, there is provided a rail arrangement comprising: a rail; a resilient layer around at least the base of the rail; and a shell for receiving the rail, wherein the arrangement further comprises a side piece received within the shell on one side of the rail, the side piece having a first height at one side against the rail and a greater second height corresponding approximately to the height of the rail at the opposite side.

This arrangement enables a rectangular rail cross section to be retained within areas where a flat surface is required. The side piece, which is preferably removable, defines the required flangeway gap for the wheel flange, and the side piece or the shell define the stop to which the road surface is prepared.

The wider shell, for receiving the rail and the side piece, may include the normal shell and a modifying shell portion. Thus, the shell may comprise first and second outer side walls and an inner side wall between the outer side walls, wherein the first outer side wall and the inner side wall define a chamber for the rail (which is the conventional shell shape) and the second outer side wall and the inner side wall define a chamber for the side piece (the second outer wall being a modifying piece).

The side piece can be symmetrical about a centre line dividing the side piece into a top half and a bottom half, so that it may be turned over when it is worn.

According to a fifth aspect of the invention, there is provided a rail arrangement comprising: first and second rails; a centre piece received within the shell between the first and second rails, the centre piece having a height lower than the height of the rails a resilient layer around at least the base of the rails; and a shell for receiving the rails and centre piece. This arrangement enables a dual gauge system to be formed from two rectangular rails in a shared shell, or else enables rails which are converging together (for example at a crossing) to be mounted in a shared shell.

According to a sixth aspect of the invention, there is provided a rail arrangement comprising: a rail; a resilient layer around at least the base of the rail; and a shell for receiving the rail and the resilient layer around the rail, wherein the shell has approximately equal height on both sides, and wherein on one side of the rail, the shape of the shell corresponds to the shape of the side of the rail, and on the opposite side of the rail, a top portion of the shell has a enlarged width such that a gap is defined between the top of the rail and the shell.

This provides an alternative way of providing a flangeway gap, which requires a wider shell with a modified top portion, rather than a separate insert.

Examples of the invention will now be described in detail with reference to the accompanying drawings in which:

Figure 1 shows a known rail cross section which is an alternative to more conventional I-beam rails;

Figure 2 shows a first rail arrangement of the invention;

Figure 3 shows a second rail arrangement of the invention for I-beam rails; Figure 4 shows one way of providing vertical height adjustment;

Figure 5 shows one way of provide vertical and lateral adjustment;

Figure 6 shows .a first modification to Figure 3

Figure 7 shows a second modification to Figure 3

Figure 8 shows a modification to Figure 2; Figure 9 shows a third rail arrangement of the invention;

Figure 10 shows a fourth rail arrangement of the invention for street rail systems;

Figure 11 shows a fifth rail arrangement of the invention; Figure 12 shows a sixth rail arrangement of the invention providing mass damping;

Figure 13 shows a first modification to the arrangement of Figure 12;

Figure 14 shows a second modification to the arrangement of Figure 12; Figure 15 shows a seventh rail arrangement of the invention;

Figure 16 shows a modification to the arrangement of Figure 15;

Figure 17A shows a known arrangement which is a slight variation to Figure 1;

Figure 17B shows a first modification to Figure 17A to provide a street system;

Figure 18 shows a second modification to Figure 17A to provide a street system;

Figure 19 shows a third modification to Figure 17A to provide a dual gauge system;

Figure 20 shows a modification to Figure 17B;

Figure 21 shows a modification to Figure 19; Figure 22 shows an eighth rail arrangement of the invention;

Figure 23 shows a first modification to Figure 22.

Figure 24 shows a second modification to Figure 22.

Figure 25 shows a third modification to Figure 22; and

Figure 26 shows a fourth modification to Figure 22.

Figure 2 shows a rail arrangement of the invention. The rail 30 is surrounded by a resilient layer 32, and the rail and layer 32 are received as a push fit in an inner shell 34, in a similar way that the rail 20 and fill 26 in Figure 1 are received in the shell 22.

In the arrangement of the Figure 2, the inner shell 34 is itself removably received in an outer shell 36, with a further resilient layer 38 between the inner and outer shells 34,36. This arrangement thus, provides two resilient damping components 32,38. The inner shape of the inner shell 34 is designed to cooperate with the rail, and the outer shape is designed to cooperate with the outer shell 36.

The further resilient layer 38 may be a pre- formed item or it may be a grout layer applied after the inner shell and rail are in position. This grout may be a poured elastomer or may a concrete based material. The use of a grout enables lateral adjustment of the position of the inner shell relative to the outer shell.

The outer shell is fixed into the track foundation either by grouting into a trough or by casting directly into the concrete.

This design enables the inner shell to provide different relative positioning of the rail 30 with respect to the outer shell 36 and therefore the rail foundations. Thus, different shapes of inner shell can be used to take account of sinking of the foundations, for example by providing different designs of inner shell 34 having different thicknesses at the base part beneath the rail.

The inner shell is preferably a pre- formed item (moulded, extruded or pulltruded), for example accurately pre-cast concrete, so that it can define the inner profile for retaining the rail.

In the example of Figure 2, the inner shell 34 is relatively thick, and the significant mass of the inner shell can be used for mass damping the rail 30 and/or the inner shell can perform a noise damping function. In particular, any vibration of the rail 30 is coupled to the inner shell 34 through the layer 32, and the size (particularly the thickness) of the inner shell 34 can be tailored to provide damping of these vibrations.

In this case, the material of the layer 32 is selected to be harder than the layer 38 and transfers load to excite the mass damping component 34. The layer 32 is then a firm resilient material, such as a hard rubber.

The inner shell also enables a non-rectangular rail to be fitted into a rectangular outer shell. As shown in Figure 3, the rail 30 may have an I-beam cross section with a base, a head and a central flange region. The inner shell can have an inner profile corresponding to the outer shape of the rail, and a substantially rectangular outer shape. This outer shape is designed for cooperation with the outer shell 36. The inner shell has a two-piece construction so that it may be fitted around the rail 30, each piece comprising a lateral portion. This provides a more efficient use of metal in the rail, but still enables the push fit system to be implemented. Again, the inner shell 34 may provide mass damping.

Figure 4 shows an arrangement in which there is no resilient layer between the inner and outer shells 34,36, and in which the inner shell is a frictional fit inside the outer shell. A wedge piece 31 may be provided (in addition to friction) to prevent uplift of the inner shell 34 relative to the outer shell. Figure 4 also shows how adjustment of the height of the rail and the inner shell can be achieved using a base portion 33 which has a thickness selected in dependence on the required lift of the rail. In Figure 5, a fill 35 is provided laterally outside the inner shell 34 so that the lateral positioning of the inner shell has some freedom, and when in the correct position, the lateral fill 35, for example a poured elastomer or poured (or pumped) concrete, can be applied. The inner shell can again lifted by cutting the fill 35 vertically downwards, so that the base portion 33 can be changed to vary the height.

In the examples of Figures 2 and 3, the inner shell is shaped to provide a detent with the outer shell, so as to prevent uplift of the inner shell in use. It is instead possible to rely upon friction alone. Figure 6 shows an arrangement based on Figure 3 in which the inner shell 34 has vertical sides. In order to further prevent uplift, securing blocks 37 may be provided intermittently along the rail length.

Figure 7 shows a modification to Figure 6, in which the outer shell, instead of being formed as a preformed pad, is formed as a thicker grout layer 39. This allows lateral alignment of the rail and inner shell 34. The grout layer 39 can then be used for height adjustment instead of the inner shell 34. For example, the grout may applied through tubes running through the inner shell 34, with levelling nuts at the base of the tubes. A levelling bolt is used to raise the rail 30 and inner shell 34 (in known manner) and grout can then be pumped to fill the created space.

In the examples above, the inner shell 34 and the outer shell 36 (or 39 in Figure 7) are separated only by a resilient layer. In Figure 8, a thin pre-formed inner shell 34 is used, and an additional precast concrete block 34A is provided between the inner shell 34 and the resilient layer 38. This means that the components which have high tolerance requirements are all moulded (or extruded or pulltruded) components - the inner shell and the resilient layer 32, The block 34A can easily be pre-cast or cast around the inner shell as the tolerance requirements are low. Height adjustment can be carried out by making the outer shell 36 a grout layer as explained with reference to Figure 7.

It will be apparent from the various examples above that the inner shell can be held in place with respect to the outer shell by friction, a wedge arrangement, a mechanical detent, an injected fill which acts as a glue, or indeed any combination of these.

The rail can be retained in the inner shell by friction or by a detent shaping or a combination of these. In addition, the inner shell can be squeezed against the rail when applying a layer around the inner shell (for example the fill 35 in Figure 5) to increase the frictional retention of the rail. This may allow the rail to have vertical sides.

As shown in Figure 9, the inner shell may be defined by a poured elastomer 40. In this case, the positioning of the rail 30 relative to the outer shell is not critical, so that the outer shell may be pre-cast into the concrete foundation. The elastomer fill 40 can then be installed in situ, and slight lateral or vertical adjustment of the rail position can be tolerated. Surface treatment of the inner surface of the outer shell 36 can allow the cured elastomer to be removable (with the rail) from the outer shell 36. In this example, the elastomer 40 acts both as the resilient cushion and the inner shell, and may also be provided with additional mass damping components 42, such as metal rods running along the structure.

In the example of Figure 10, the rail is a tramway rail, having a so-called flangeway gap 50 in the rail head. In addition, a separate resilient layer 32 is again provided around the rail. This . may be two-piece (see dotted line at the base) or it may be wrapped around the rail. In this example, the rail is grouted into the channel defined by the outer shell 36, and this grout 52 defines the inner shell. The grouting operation again enables the position of the rail in the channel defined by the outer shell 36 to be less critical so that the outer shell can be pre-cast in the rail foundations. The grout may be a sand and cement mortar or it may be asphalt or a poured elastomer (as in Figure 9).

If the sides of the outer shell 36 in Figures 9 and 10 are vertical, the rail may be removable. For example, the inner surface of the outer shell 36 can be coated with a de-bonding agent so that the rail and elastomer or grout can be removed.

The example of Figure 11 has inner and outer shells 34, 36 and the space between is filled with grout 52 or a poured thermosetting elastomer layer. Again this enables the outer shell 36 to be pre-cast into the bed, but does not allow the simple removal of the inner shell 34 (as in the example of Figure 2). However, initial control of the height of the rail is achieved when applying the grout (or other material filler). For example, the grout may be pumped through a channel as described above. The inner shell can, however, be cut out and removed and re-grouted into an adjusted position. For this purpose, a grout injection tube may be provided within the structure of the grout layer 52 or externally as shown in dotted lines.

Again, if the sides of the outer shell 36 are vertical, the inner shell and layer 52 may be removable. For example, the inner surface of the outer shell 36 can be coated with a de-bonding agent so that the inner shell and the grout 52 can be removed. The design needs to ensure that the inner shell cannot lift in normal use, for example by ensuring sufficient weight and therefore thickness of the grout layer 52 or sufficient friction at the interface between the inner surface of the outer shell and the grout to prevent vertical movement of the grout and shell.

In the examples above, a heavy inner shell can be used to provide mass damping as well as providing the. desired adjustability. A further solution to providing mass damping is shown in Figure 12, in which an I-beam rail 30 is received in a shell 60, with a resilient layer 62 between the rail and the shell. Filler portions 62 are provided one each side of the flange region of the rail 30, such that the outer shape of the rail and the filler portions is substantially rectangular, to fit into the outer shell 60 in the same way as the rail system of Figure 1. The filler portions are preformed, for example moulded, components. These may be made from pre-cast concrete, nylon, plastic or a polymer material, as examples. They may be cast, pulltruded, extruded or formed in other ways, typically less expensively than the forming process for the rail steel which they replace. The tight tolerances of the engagement mechanism of the rail shape can thus be removed from the rail rolling operation and be transferred to the manufacturing operation of the filler portions.

The advantage of returning to an I-beam rail section is that the given weight of rail is more efficiently distributed, which improves fatigue life (for a given volume of material) or else reduces cost for a given fatigue strength. The handling weight can be reduced, and the handling of I-beam rails is more convenient.

The filler portions can be provided with a number of indent locations, so that height compensation can be achieved with the same filler portions, and all that is needed is an additional base support.

As shown on the left of Figure 12, at least one of the filler portions 64 comprises a first low resilience mouldable (or extrudable) material and embedded mass damping portions 65 of a second material, which is more dense than the first material. Portions 65 are typically metal inserts.

The tolerance required in the manufacture of the mass damping components is also low, as they are surrounded by the low resilience material, which can take up tolerance variations in both the rail and the mass damping inserts (which will typically be metal or concrete like material ).

In the example of Figure 12, indents 66 are formed in the filler portions 64, and the overall width provided by the filler portions is the same as the width of the rail head. In the example of Figure 13, the filler portions 64 have flat outer faces, slightly narrower than the rail head, so that indent steps are effectively defined at the boundary between the filler portions 64 and the head and foot of the rail 30. As shown in Figures 12 and 13, the mass damping components 65 may comprise a number of rods (Figure 12) or a single shaft (Figure 13) not necessarily of circular cross section.

In each case, the rail is coupled to the mass damping element through a resilient, but low resilience, material. This is needed to transfer shock waves from the rail to the mass damping component and to excite vibration in the mass damping component. In known manner, this excitation of the mass damping component can be tuned to damp the vibrations in the rail, which have resulted from mechanical excitation by the train (or tram) wheels.

Figure 14 shows how the filler portions 64 may be modified to enable a rail having a wider base than rail head to be accommodated within the substantially rectangular shell 60. Essentially, the width of the rail with the filler portions is substantially constant, and must therefore be brought to the maximum width of the rail by the filler portions if the rail is required to be removable. In the case of Figure 14, the maximum width is the width of the base.

The filler portions provide mass damping as well as removing the tolerances from the rail manufacture. In the examples of Figures 2 and 3, mass damping is provided by a heavy inner shell which surrounds the rail, and thereby requires a wider outer shell and increases the required width of the rail assembly. The examples of Figures 12 to 14 do not require increased width, but there is a limited volume of space for the mass damping inserts.

Figure 15 shows an alternative arrangement which provides mass damping without increasing the width of the assembly. A mass damping component 70 is provided beneath the rail 30 and having the same width as the rail. The mass of the component is then tuned to provide the required mass damping. The resilient layer 62 surrounds the rail and the mass damping component 70, and a shock transfer member 72 is provided between them. This member 72 is a firm resilient material, but of low resilience. For example, member 72 may be a hard rubber which is softer than the rail or the damping component 70 but harder than the layer 62. The resilient layer 62 is typically a microcellular polyurethane. The member 72 transfers vibrations resiliently to the mass damping component to damp out vibrations in the rail excited by the wheels. This intermediate harder layer will adsorb the energy from the rail and warm up. Figure 16 shows a different thickness component 70.

Figure 17A shows a known arrangement similar to Figure 1. The differences relate to the specific shapes of the components. Thus, the rail 30 is received by a shell 22 with a resilient layer 26 between them. The shell has pinch points 23 as shown. Various modifications to this design provided by the invention will now be described, for providing a flangeway gap.

These flangeway gaps are required in main line embedded rail tracks, embedded crane or gantry tracks or tram tracks used in the street, in level crossings and in switches and crossovers in other tracks.

Figure 17B shows an arrangement in which a side piece 80 is received within the shell 22 on one side of the rail 30. The shell 22 is thus wider than that of Figure 17A, and this can be achieved using a side extension 82 to the shell. The side piece 80 is below full height at one side 84 against the rail and is full height at the opposite side 86.

One side of the side piece has a shape corresponding to the side of the rail (the right side in Figure 17B) so that it provides the detent mechanism with the shell. The inner side of the side piece is shaped to engage the outer surface of the part 22V of the shell.

The side piece defines the required flangeway gap 88 for a tramway rail, and in the example of Figure 17B, the full height side 86 of the side piece 80 defines a stop against which the road surface can be prepared.

The use of the side extension 82 results in first and second outer side walls 22A, 22B and the inner side wall 22C between them. The same shape of resilient layer 26 can be used, and this has advantages for rails which pass between surface mounted regions

(for example at switches and crossings) and normal sections of rail. The rail is thus supported in identical manner throughout, and the transition between normal embedded rail support as in Figure 17A and the surface mounted support is facilitated.

As shown in Figure 18, the side piece 80 can have symmetrical top and bottom halves, so that it may be turned over when it is worn. In this example, the shell 22 does not have a centre section and is designed specifically for this use. Note also that the rail itself may also be reversible in all examples.

In Figure 19, a centre piece 90 is received within the shell 22 between first and second rails 30A, 30B, the centre piece having a height lower than the height of the rails. This arrangement enables a dual gauge system to be formed from two substantially rectangular rails in a shared shell. The support of two rails closely side by side is also required in tapered sections of track in switches and crossovers.

In the examples of Figures 18 and 19, the side piece 80 or centre piece 90 are separate components. Of course, a rail may be formed with the combined profile, either with one flangeway gap only on the upper face, or with a flangeway gap on upper and lower faces to be reversible.

Figure 20 shows a slight modification to Figure 17B, in which the shell extension 82 is full height .and thereby defines the stop against which the road surface is prepared.

Although the rail in the examples of Figures 17 to 20 are rectangular section rails, they may equally be I-beam rails with inserts to make them fit the shell arrangement. These concepts may also be applied to the twin shell arrangements described for example with reference to Figures 2 and 11.

Figure 21 shows a slight modification to Figure 19, in which the centre piece 90 extends not only between the rails 30A, 30B but also beneath the rails. This provides a constant bearing area and ensures that the required support resilience is provided without requiring variations in the compliance of the (elastomeric) resilient layer 26. In addition, by providing a low resilience (for example hard rubber) layer between the rails and the centre piece 90, it is possible for the centre piece to provides mass damping, in the manner described above. This layer can surround the base of the rails or can line only the bottom and inside face (namely the side in contact with the centre piece 90) of each rail.

These examples provide a flangeway gap, whether for tramway systems or between dual gauge rails, by providing an insert alongside the rail. The insert may be made of steel, although manufacture from plastics, composites, polyurethane or rigid elastomer materials may be possible. Different size flangeway gaps may be desirable for curves and for straights, requiring different versions of the modified shell and insert.

An alternative approach is to modify the shell. In the example of Figure 22, the shell 22 has equal height on both sides. On one side of the rail (the left in Figure 22), the shape of the shell corresponds to the shape of the side of the rail. On the opposite side of the rail, a top portion 92 of the shell has an enlarged width such that a gap 94 is defined between the top of the rail and the shell 22. This gap is the required flangeway gap. As shown in Figure 23, a hard insert 96 of steel or polyurethane can line the widened portion of the shell. This insert protects against damage and wear, for example from contact with the vehicle wheels, and is replaceable.

In Figures 22 and 23. the top portion 92 of the shell is an integral part of the shell. However, it may be formed as a separate extension piece as shown in Figures 24 and 25. In Figure 25, an overlap is provided. Different sizes of separate piece may be used with a standard shell to provide different flangeway gaps. This extension piece will have outer tangs as shown or be formed externally in other ways to enable it to engage with the concrete support.

Figure 26 shows another version in which a vertical metal insert 98 is provided which acts as a wear plate, and there is a resilient layer and/or shims 99 between the insert 98 and the shell 22.

These examples all provide flangeway gaps without requiring specially modified rail shapes. In all examples above, the rail has a profile selected to provide a detent function with the shell. However, the detent may not be required, and the engagement of the rail with the shell can be purely frictional, particularly if the rail has sufficient mass that it does not lift during traffic flow. Intermittent clips additionally may be provided for holding the rail down.

Various modifications will be apparent to those skilled in the art.

Claims

1. A rail arrangement comprising: a rail; a resilient layer around at least the base of the rail; and an inner shell for receiving the rail and the resilient layer, and having an inner profile corresponding to the outer shape of the resilient layer, wherein the inner shell and rail are received within an outer shell.

2. A rail arrangement as claimed in claim 1, wherein the inner shell and rail are removably received within an outer shell.

3. A rail arrangement as claimed in claim 1 or 2, wherein the inner shell is formed from pre-cast concrete.

4. A rail arrangement as claimed in any preceding claim, wherein the inner shell is thicker than the resilient layer.

5. A rail arrangement as claimed in any preceding claim, wherein the rail has base, a head and a central flange region, and wherein the inner shell has an inner profile corresponding to the outer shape of the rail and a substantially rectangular outer shape.

6. A rail arrangement as claimed in claim 5, wherein the inner shell has a two- piece cross section, each piece comprising a lateral portion.

7. A rail arrangement as claimed in any one of claims 1 to 4, wherein the inner shell provides mass damping of the rail.

8. A rail arrangement as claimed in claim 1 or 2, wherein a grout layer is provided between the inner shell and the outer shell.

9. A rail arrangement comprising: a rail; a resilient layer around at least the base of the rail; and a shell for receiving the rail and the resilient layer around the rail, wherein the rail has a base, a head and a central flange region, and wherein filler portions are provided one each side of the flange region, such that the outer shape of the rail and the filler portions is substantially rectangular, and wherein at least one of the filler portions comprises a first mouldable material and embedded mass damping portions of a second material, which is more dense than the first material.

10. A rail arrangement comprising: a rail; a mass damping component beneath the rail and having a width substantially equal to the width of the base of the rail; a resilient layer around the rail and the mass damping component; and a shell for receiving the rail and the mass damping component.

11. A rail arrangement as claimed in claim 10, wherein the rail has a substantially rectangular cross section.

12. A rail arrangement as claimed in claim 10 or 11, wherein an interface component is provided between the base of the rail and the mass damping component.

13. A rail arrangement comprising: a rail; a resilient layer around at least the base of the rail; and a shell for receiving the rail, wherein the arrangement further comprises a side piece received within the shell on one side of the rail, the side piece having a first height at one side against the rail and a greater second height corresponding to the height of the rail at the opposite side.

14. A rail arrangement as claimed in claim 13, wherein the shell comprises first and second outer side walls and an inner side wall between the outer side walls, wherein the first outer side wall and the inner side wall define a chamber for the rail and the second outer side wall and the inner side wall define a chamber for the side piece.

15. A rail arrangement as claimed in claim 13, wherein the side piece is symmetrical about a centre line dividing the side piece into a top half and a bottom half.

16. A rail arrangement comprising: first and second rails; a centre piece received within the shell between the first and second rails, the centre piece having a height lower than the height of the rails a resilient layer around at least the base of the rails; and a shell for receiving the rails and centre piece.

17. A rail arrangement comprising: a rail; a resilient layer around at least the base of the rail; and a shell for receiving the rail and the resilient layer around the rail, wherein the shell has approximately equal height on both sides, and wherein on one side of the rail, the shape of the shell corresponds to the shape of the side of the rail, and on the opposite side of the rail, a top portion of the shell has a enlarged width such that a gap is defined between the top of the rail and the shell.

18. A rail arrangement as claimed in claim 17, wherein the top portion of the shell is provided with a lining piece.