RAILWAY FOR ABSORPTION OF NOISE OF TRACK VEHICLES

The invention concerns a railway with rails embedded in a hardening, whereby the top side of the hardening between the rails is situated between the foot of the rails and practically the top side of the rails and whereby sounds of railway vehicles moving over this railway are absorbed.

According to the present state of the art, ballastless railways are built whereby the rails are fixed to a concrete construction with the bottom side of the rail foot. The rails are hereby usually entirely embedded in a hardening which may consist of a paving on the top side whose height is practically equal to the height of the top side of the rails. This technique is mainly used for tram tracks and level crossings whereby the rails are entirely worked into the road surface, but it is also increasingly being used to replace traditional ballast railways as it requires much less maintenance.

Moreover, such embedded rails are aligned as well as possible, and they are provided with vibration-isolating material so as to transfer as few vibrations or as little noise as possible to the environment via the rails. hi order to further reduce sound nuisance of railway vehicles moving over railways, efforts are being made to make the vehicles themselves less noisy.

As the sound nuisance of the transmission of sound via the rails is already strongly reduced, the share of the direct sound nuisance of the railway vehicles themselves has become more important in the continuing fight against sound nuisance of railways.

The invention aims to remedy this by providing a railway which efficiently reduces the sound of railway vehicles as they move over a railway with rails that are embedded in a hardening.

To this aim, a sound-absorbing layer is provided on the top side of this hardening, between the rails, comprising standing fibres made of a synthetic material as claimed in the appended claims for the absorption of sounds made by railway vehicles moving over a railway. Practically, the sound-absorbing layer is formed of a mat with standing synthetic fibres having a height of almost 4 to 7 cm.

In an advantageous manner, these synthetic fibres are made of polyethylene and/or polypropylene.

In a particularly advantageous manner, the standing synthetic fibres consist of the filaments of filament yarns having a width of 9 to 0.8 mm. According to a special embodiment, the standing synthetic fibres comprise monofilament yarn having a width of 0.8 to 4 mm on the one hand, preferably of 1 to 3 mm, a thickness of 100 to 250 μm, preferably of 110 to 150 μm and a count of 1,000 to 3,000 dtex, and fibrillated yarn having a width of 5 to 10 mm, preferably of 6 to 9 mm, a thickness of 60 to 200 μm, preferably of 60 to 100 μm and a count of 5,000 to 12,000 dtex on the other hand.

The invention also concerns a method for building such a railway and a prefab railway element that is provided with a sound-absorbing layer.

Other particularities and advantages of the invention will become clear from the following description of an embodiment of the method and the device according to the invention; this description is given as an example only and it does not limit the scope of the claimed protection in any way; the figures of reference used hereafter relate to the accompanying drawings.

Figure 1 is a schematic representation of a cross section of a railway with embedded rails, provided with a sound-absorbing layer according to the invention, whereby the rails are embedded in a concrete hardening.

Figure 2 is a schematic representation of a cross section of a railway with embedded rails, provided with a sound-absorbing layer according to the invention, whereby a hardening of gravel is provided between the embedded rails.

In the different drawings, the same figures of reference refer to identical or analogous elements.

The invention in particular concerns railways having rails that are embedded in a hardening; in other words, railways that are provided with a hardening that is higher between the rails than the foot of the rails, which is the lower part of the rails with which the latter are fixed. According to a preferred embodiment of the invention, as represented in figure 1, rails 1 of a railway 2 are fixed to a concrete construction 3 and are further

embedded in a concrete hardening 4, such that the top side 5 of the rails 1 runs practically equal to the top side 6 of the concrete hardening 4. The rails 1 can hereby be surrounded by a vibration-isolating material 7. The concrete construction 3 may for example also be the base of a prefab railway element. On top of the concrete hardening 4, between the rails 1, is glued a sound-absorbing layer 8 according to this preferred embodiment of the invention. This can be done for example with polyurethane glue. This sound-absorbing layer 8 is formed of a mat 9 with standing, flexible synthetic fibres 10 having a free end.

For an optimal sound absorption, the standing synthetic fibres 10 are formed of different standing synthetic yarn filaments made of polyethylene and/or polypropylene.

According to this preferred embodiment of the invention, the mat 9 is tufted, whereby the tufts protruding from the mat form the standing synthetic fibres 10.

These tufts comprise filament yarns composed of different filament yarns, in particular monofilament yarns and fibrillated filament yarns.

The filaments have a thickness varying between 100 to 250 micron and they have a pile height of 15 to 60 mm, preferably almost 35 mm. The mat has a density of almost 75,000 to 100,000 filaments per m ² .

The total height of the sound-absorbing layer amounts to 35 to 60 mm. Between the standing synthetic fibres is provided a bed of silica sand, in an amount of preferably some 10 to 20 kg per m ² . This sand may possibly be replaced in part or as a whole by another granular material such as rubber granules.

Other granular materials or even a synthetic resin with possibly better sound-absorbing qualities may also be applied within the scope of the invention. The height of the bed is such that the free ends of the standing synthetic fibres extend above it. Preferably, the length of the synthetic fibres above the bed is not smaller than 2 to 3 cm. The synthetic fibres, in particular the wider filaments, prevent erosion of the bed by wind and/or water.

For aesthetical reasons, synthetic fibres may preferably be used that look like natural grass or like the paving in the surrounding area. Thus, the synthetic fibres could for example also be formed of mushroom-shaped burls.