The present invention relates to a method for installation of an embedded rail system, wherein a railway track support structure has an elongated open-topped channel and wherein a steel rail of a railway track is positioned in the channel. The method comprises the step of pouring a pourable resilient compound which cures over time in the channel with the rail and remains elastic when cured, the compound then bonding to the rail and in cured state providing continuous vertical and horizontal support to the rail.
Such embedded rail systems (ERS) are generally known in the field of railway tracks for e.g. train, tram, metro, crane and other railbound vehicle applications. Often polyurethane based elastomeric compounds are used to obtain the required resilient behaviour as well as provide a reliable connection of the rail to the railway track support structure in the absence of other connection members. The embedded rail system is for instance found in level crossings and (steel) bridges.
In the prior art approach the installation of such an embedded rail system often involved the preparation of the outer surface of the steel rail that were to be bonded to the compound by application of a primer on the steel surface. The purpose of the primer is to establish a chemical bond with the curing compound, based on polymerisation. When done properly a very strong and reliable bond is obtained in this manner.
In situ installation of such an embedded rail system could however give rise to practical problems, often compounded by the fact that installation has to be done in a short time, e.g. during the night when work is done on an existing track. Problems are e.g. encountered when working in wet, moist and/or dust/dirt-laden conditions. Such conditions are bound to have a detrimental effect on the primer, with the result that no bond or an insufficient bond with the compound is obtained. Protocol may even prohibit that the compound is actually poured under certain conditions thus causing undesirable problems such as the availability of the track for railway services. A delay in pouring the compound may then result in the primer become inactive over time, requiring that a new layer of primer is applied.
It is an object of the present invention to overcome or at least alleviate the above-mentioned installation problems.
The present invention achieves this aim by providing a method according to the preamble of claim 1, wherein- prior to the pouring of the resilient compound - an anchoring sheet is attached directly to the rail, the anchoring sheet having a multitude of anchoring formations, so that upon curing of the compound a mechanical interlock is obtained with the cured compound.
The attachment of an anchoring sheet to the rail can be done in situ, but it is preferred to attach the anchoring sheet at a remote location (preferably indoors in a controlled environment) e.g. in a tent close to the railway track or a remote specialized factory.
Attaching such an anchoring sheet can e.g. be done with an adhesive applied between the anchoring sheet and the steel surface of the rail and is generally less critical then the application of the primer as in the prior art method.
In fact, if moisture or water is present on the anchoring sheet, the compound is likely to expel most of the moist/water in upward direction as the level of the compound in the channel rises during the pouring step. Of course it is advisable to remove dirt and dust from the anchoring sheet prior to the pouring, e.g. by a high-pressure spraying with a water and/or air pistol. Any water left in the anchoring sheet, possibly due to the high-pressure treatment, is preferably removed from the installation site prior to the pouring, e.g. using a blower.
Preferably anchoring sheets are at least attached to opposed side surfaces of the rail. This ensures adequate bonding to resist vertical rail motion, also including uplift of the rail.
Preferably the rail has a rail head, a vertical web, and a foot broader than the vertical web, and anchoring sheets are attached to at least the opposed side surfaces of the vertical web, preferably also to at least the upper surface of the foot.
It is also possible that anchoring sheets are attached so as to extend over the side surfaces of the rail head, or such that these sheets only extend over the side surfaces of the rail head. In the latter embodiment it can be envisaged that void forming members, also known as filling members, such as relatively lightweight (e.g. cellular foam) members are placed against the side faces of the rails below the rail head.
In general the provision of the anchoring sheets on the rail will serve to avoid release of the compound from the rail, and thus avoid problems associated with the ingress of water.
It is envisaged that the anchoring sheet can be attached to the rail with an adhesive. Suitable adhesives, e.g. epoxy, are less sensitive to conditions during application than the primer used in the prior art approach.
The adhesive for attachment of the anchoring sheet could be an adhesive tape, possibly the adhesive tape having two opposed adhesive sides. Such a tape could be attached to the anchoring sheet prior to attachment of the sheet to the rail (or support structure as will be explained below). The adhesive side could be covered by a removable liner sheet, so that the adhesive is only exposed shortly before attachment of the anchoring sheet.
As will be explained with reference to a possible embodiment the step of attaching the anchoring sheet to the rail could well be performed at a location remote from the railway track, preferably indoors. Also the attachment could be performed more than 24 hours before pouring of the compound.
The anchoring sheet could be so flexible that it is supplied from a roll, thereby facilitating installation of the system.
The anchoring sheet could be a multilayer sheet, e.g. having multiple layers (woven and/or non-woven) with openings therein allowing the compound to penetrate into and between the layers thus effecting the mechanical interlock. Geotextiles are available with such a structure.
In a possible embodiment the anchoring sheet is a sheet with hooks and/or loops similar to a hook-and-loop fastener system. In fact it is envisaged that sheet nowadays marketed as hook-and-loop fasteners for e.g. clothing are suitable for use in the present method. A well known alternative is the hook-and-mushroom fastener system, wherein a sheet is provided with hooks and the other sheet with mushroom members, that may also be applied in the present invention.
Preference is given to an anchoring sheet provided with looped anchoring formations, e.g. plastic loops. The loops may be small, e.g. extending between 1 and 5 millimetres from a backing layer.
In a possible embodiment the anchoring sheet comprises a backing layer (e.g. of a plastic material) that is provided with a multitude of protruding anchoring members at the side facing away from the rail.
It is possible that the entirety of the anchoring sheet is of suitable plastic, e.g. PA, PE, PP, EVA.
In another possible embodiment the anchoring sheet is a metallic sheet.
It can be envisaged that an elastic mat is placed under the rail prior to the pouring of the compound, but in another configuration there is an open space below the rail which is then filled with the compound.
In a practical embodiment, e.g. seen at level crossings, one or more void forming members are positioned in the channel. Such member can e.g. be tubes that allow the passage of an (electric) cable there through, which tubes are preferably positioned in the channel spaced a distance from the rail with the anchoring sheet prior to the pouring of the compound. When arranged spaced from the rail the void forming members do not interfere with the bonding of the compound to the anchoring sheet.
As is known in the art the railway track support structure could be a concrete slab, e.g. a level crossing slab.
In another embodiment the railway track support structure is a bridge, e.g. a steel bridge.
In a preferred embodiment the compound is a polyurethane based compound.
In a highly preferred embodiment one or more further anchoring sheets with a multitude of anchoring formations have been attached on the surface of the channel in the railway track structure prior to the pouring of the compound. This is done to establish a mechanical bond between the cured compound and the channel surface(s) of the track structure.
In a possible embodiment the channel is made of metal, e.g. by a metal channel member supported by a concrete structure (such as a slab), or by the entire support structure being made of metal, e.g. a steel bridge. An anchoring sheet could be attached to the channel in the manner described with respect to the attachment of an anchoring sheet to the rail, e.g. using an epoxy adhesive.
In another practical embodiment the support structure or a channel member of said support structure is made of concrete, so that the surface of the channel is of concrete. An anchoring sheet can be attached to the concrete by suitable attachment means, e.g. using an adhesive such as epoxy.
In a highly preferred embodiment the railway track support structure is a concrete support structure that has been cast using a suitable formwork or mould, wherein a double-sided anchoring sheet is used which is to be attached to the concrete, which anchoring sheet has a central layer that is substantially impenetrable for the liquid concrete and on opposed sides thereof is provided with a multitude of anchoring formations.
The double-sided anchoring sheet is then mounted to the surface of the formwork or mould defining the channel, so that upon casting of the concrete, the anchoring formations on the side facing away from the formwork or mould establish a mechanical bond with the concrete. Upon removal of the formwork or mould the side with anchoring formations facing away from the concrete is exposed, so that upon pouring the resilient compound into the channel with the rail a mechanical interlock of the compound with the concrete is obtained via said double-sided anchoring sheet.
The present invention also relates to an embedded rail system, wherein a railway track support structure has an elongated open-topped channel and wherein a steel rail of a railway track is positioned in the channel, and wherein a pourable resilient compound which cures over time in the channel with the rail is bonded to the rail and provides continuous vertical and horizontal support to the rail, which is characterised in that an anchoring sheet is attached directly to the rail, the anchoring sheet having a multitude of anchoring formations, so that a mechanical interlock is obtained with the cured compound.
The present invention also relates to a steel rail for use in an embedded rail system, wherein a railway track support structure has an elongated open-topped channel and wherein the steel rail is to be positioned in the channel, and wherein a pourable resilient compound which cures over time is to be poured in the channel with the rail so that the compound is bonded to the rail and provides continuous vertical and horizontal support to the rail, characterized in that an anchoring sheet is attached directly to the rail, the anchoring sheet having a multitude of anchoring formations, so that a mechanical interlock is obtained with the cured compound.
The present invention also relates to a level crossing of a railway track system comprising one or more concrete slabs provided with parallel elongated open-topped channels and wherein a steel rail is positioned in each channel, and wherein a pourable resilient compound which cures over time is poured in each channel with the rail so that the compound is bonded to the rail and provides continuous vertical and horizontal support to the rail, characterized in that an anchoring sheet is attached directly to the rail, the anchoring sheet having a multitude of anchoring formations, so that a mechanical interlock is obtained with the cured compound.
The invention also relates to a method for installation of an embedded rail system as in claim 23, wherein a railway track support structure has an elongated open-topped channel and wherein a steel rail of a railway track is positioned in the channel, and wherein the method comprises the step of pouring a pourable resilient compound which cures over time in the channel with the rail, the compound then bonding to the rail and in cured state providing continuous vertical and horizontal support to the rail, characterised in that - prior to the pouring of the resilient compound - an anchoring sheet is attached directly to one or more surfaces of the channel in the railway track support structure, the anchoring sheet having a multitude of anchoring formations, so that upon curing of the compound a mechanical interlock is obtained with the cured compound.
The present invention also relates to a railway track support structure having an elongated open-topped channel to receive therein a steel rail of a railway track to form an embedded rail system, wherein a pourable resilient compound which cures over time will be poured in the channel with the rail, the compound then bonding to the rail and in cured state providing continuous vertical and horizontal support to the rail, which railway track support structure is characterised in that - prior to the pouring of the resilient compound - an anchoring sheet is attached directly to one or more surfaces of the channel in the railway track support structure, the anchoring sheet having a multitude of anchoring formations, so that upon curing of the compound a mechanical interlock is obtained with the cured compound.
It will be appreciated that the installation of the embedded rail system can also involve the use of one or more temporary mould members to form the channel or part of the channel into which the compound is poured. After curing of the compound the one or more temporary mould members are removed and the permanent railway track support structure is compteted.
Further preferred embodiments of the method and other aspects of the invention are disclosed in the appended claims and in the description with reference to the drawings. In the drawings:
Also shown is a steel rail 10 of a railway track which is positioned in the channel 2 so as to be spaced from the side faces of the channel 2 and here also from the bottom face of the channel 2.
The rail shown as an example here has a rail head 10a, a vertical web 10b, and a foot 10c that is broader than the vertical web 10b.
Anchoring sheets 20 have been attached to opposed surfaces of the rail 10, here so as to extent over all or at least the major part of the vertical web 20, and as is preferred also over at least the upper surfaces of the foot 10c. The anchoring sheets 20 each have a multitude of anchoring formations of which examples will be elucidated in more detail below.
In order to arrive at the embedded rail system a pourable resilient compound which cures over time is then poured into the channel 2 with the rail 10 therein. As the compound cures a mechanical interlock is obtained between the anchoring sheets 20 and the cured compound 30. In general, the anchoring sheets 20 transmit forces from the rail 10 via the cured compound to the railway track support structure 2. Such forces may be horizontal, vertical and/ or longitudinal forces.
The compound remains elastic when cured and provides continuous vertical and horizontal resilient support to the rail.
The anchoring sheet 20 is shown by way of example in
The entirety of the anchoring sheet 20 could be of suitable plastic, e.g. PA,PE,PP,EVA,etc. It can also be envisaged that high-strength fibres are included in the sheet 20.
The anchoring sheet 20 could be a sheet with hooks and/or loops similar to a hook-and-loop fastener system.
Preferably the anchoring sheet is attached to the rail with an adhesive.
The step of attaching the anchoring sheet to the rail is preferably performed at a location remote from the railway track, preferably indoors. One could envisage that a railway level-crossing is made or renovated by preparing (remote from the site of the level-crossing) a new section of rail to which the anchoring sheet(s) are attached. Said new section is then brought to the site and placed in the channel (from which an old rail section may have been removed), after which the compound is poured in the channel and allowed to cure.
The anchoring sheet can be rather thin and flexible, allowing the anchoring sheet to be supplied in a roll.
Although not preferred it can be envisaged that the anchoring sheet is a metallic sheet.
In a preferred embodiment the compound is a polyurethane based compound.
As can be seen in
As in this example the structure 1 is made of concrete one could envisage that the sheets 40 are attached with a suitable adhesive to the concrete. The same is possible if the channel was made of metal.
Also shown is a steel rail 110 of a railway track which is positioned in the channel 102 so as to be spaced from the side faces of the channel 102 and here also from the bottom face of the channel 102. In the shown embodiment a pourable resilient compound which cures over time has already been poured into the channel 102 with the rail 110 therein. The cured compound is indicated with reference number 130.
The rail 110 shown as an example here is a so-called grooved rail having a groove 100d in a rail head 110a, and further comprising a vertical web 110b and a foot 110c, substantially broader than the vertical web 110b.
As is known in the art an elastic mat 150 is in this embodiment placed under the rail 110 in the channel 102 of concrete 101 prior to the pouring of the compound 130.
Anchoring sheets 120 have been attached to opposed surfaces of the rail head 110a, extending over the side surfaces of the rail head 110a. The anchoring sheets 120 have a multitude of possible anchoring formations, examples of which are shown in
Further anchoring sheets 140 are attached with a suitable adhesive to the upper region of elongated open-topped channel 102 of the concrete railway track support structure 101. The anchoring sheets 140 have a multitude of possible anchoring formations, examples of which are shown in
The anchoring sheets 120 and 140 hereby in particular prevent the intrusion of water or the like between the rail 110 and the cured compound 130 and between the concrete 101 and the cured compound. This contributes to the life time of the embedded rail system as it prevents corrosion of the rail by preventing moisture to contact the steel rail 110. It also prevents the built up of large water pressures which may result in damage of the concrete. Such water pressures may occur when trains cross a water inclusion between the cured compound 130 and the concrete 101.
Analogously,
In
The rail 210 shown as an example here has rail head 210a, and further comprising a vertical web 210b and a foot 210c, substantially broader than the vertical web 210b. Void forming members 235 are positioned in the channel spaced a distance from the side faces of the vertical web 210b of the rail prior to the pouring of the compound 230. Such void forming members are known in the art and are formed e.g. by tubes that allow the passage of an (electric) cable there through.
In the embodiment of the embedded rail system of
In
The rail 310 shown as an example here has rail head 310a, and further comprising a vertical web 310b and a foot 310c, substantially broader than the vertical web 310b. Void forming members 335 are placed at a distance from the side faces of the vertical web 310b of the rail prior to the pouring of the compound.
In the embodiment of the embedded rail system of
A double-sided anchoring sheet 403 is used which is to be attached to the concrete 401. The double-sided anchoring sheet 403, as shown in detail in
Upon casting of the concrete 401, the anchoring formations 411 on the side facing away from the mould 402 establish a mechanical bond with the concrete 401.
Upon removal of the mould 402, in this embodiment by releasing the hooks 404 on the mould 402 from the loops 412 of the double-sided anchoring sheet 403, the side with anchoring formations 412 facing away from the concrete 401 is exposed.
Upon subsequent pouring of a pourable resilient compound which cures over time in the channel created by removal of the mould 402, in which channel a rail is to be positioned, a mechanical interlock of the loops 412 with the compound (not shown) is obtained, and thus a mechanical interlock of the compound (not shown) with the concrete 401 is obtained via said double-sided anchoring sheet 403.
In
The steel rail shown in
Anchoring sheets 520 have been attached to opposed surfaces of the rail 501, here so as to extent over all or at least the major part of the upper surface of the foot 501 c, and over the bottom surface of the foot 501 c, and also over part of the vertical web 501 b. The anchoring sheets 520 each have a multitude of anchoring formations of which examples are elucidated above.
In order to arrive at an embedded rail system a pourable resilient compound which cures over time is poured into the channel 503 with the rail 501 therein. As the compound cures a mechanical interlock is obtained between the anchoring sheets 520 and the cured compound 504. The compound 504 remains elastic when cured and provides continuous vertical, horizontal and longitudinal support to the rail 501.
Further anchoring sheets 540 have been attached on the surface of the channel 503 in the dedicated track support structure 502 prior to the pouring of the compound. The anchoring sheets 540 each have a multitude of anchoring formations of which examples are elucidated above.
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.