Railway with sound-proofing provision

Abstract: Railway (1), wherein the rails (2), or equivalent elements supporting and/or guiding the vehicle (5), are supported by an essentially compact foundation bed (3) made of, for example, concrete or steel, which foundation bed (3) essentially spans at least the width of the vehicle (5) moving along the rails (2) or equivalent elements, and wherein said foundation bed (3) is covered with a layer (6) of material such that the sound produced by a vehicle (5) moving along the rails (2) or equivalent elements is substantially damped.

Description: The invention relates to a railway, wherein the rails are supported by an essentially compact foundation bed made of, for example, concrete or steel, which foundation bed essentially spans at least the width of the vehicle moving along the rails and wherein said foundation bed is covered with a layer of material such that the sound produced by a vehicle moving along the rails is substantially damped. The vehicles are, for example, mobile cranes, trains, trams, and also guided buses. In the past, a railway has often been laid in a bed of gravel founded on a layer of sand. More and more, however, a concrete or steel foundation bed is being used to support the railway. Such a railway construction is known from EP-A-0404756. In this publication it is described that the rails can be embedded in a sound proofing material which may be formed of a mix of rubber particles and stone chips embedded in a polyurethane or dispersion acrylic resin binder. The known system has as a disadvantage that the sound absorbing abilities are not optimised, that the specific shape of a profile of the sound demping layer cannot be easily formed and that a relatively complex dewatering facility needs to be applied. It is an object of the present invention to provide a sound damping construction for railways in which the above problems are mitigated. Thereto the railway construction according to the present invention is characterised in that the damping material comprises asphalt or asphalt concrete with chips of stone-like material bound by a bituminous binder material and having an open pore structure of at least 10%, preferable at least 20% and defining a longitudinal rib to the side of the rails integrally formed with said layer of damping material. In particular in combination with a foundation bed made of concrete or steel, it has been found that a surprisingly expedient reduction or damping of sound is achieved by covering the foundation bed with a layer of porous, bituminously bound material which absorbs rather than reflects, and reduces the emission of vibrational noise. This layer of material preferably contains a mixture of chips of stone-like material suitably selected according to chip size, which chips are bonded by means of a bituminous, viscoelastic material. For suitable compositions of the material, reference is made to, for example, the Standard RAW provisions, pp. 334/335, under 31.26.15 "Zeer Open Asfalt Beton" [Porous Asphalt Concrete], Table T 31.19 Foundation Centre for Regulation and Investigation in Soil Mechanics, Hydraulic Engineering, and Road-Building and Traffic Technology (CROW), Ede 1990, in which, in order to increase the effect desired here, the proportion of bitumen is preferably increased, and the proportion of sand is reduced, or, for example, EP-A-0,381,903, Example 1, and 3, or, for example, NL-A-7,903,920. However, other compositions of the material are also conceivable. In particular, the bituminously bound material with open pores can be particularly easily installed and has a favourable service life. In addition, use can thus be made of a material that has already been used in road-building for decades, the processing and use properties of which are by now thoroughly known. The material can be prepared in a so-called asphalt preparation plant. Because of the open pore structure, the sound-damping layer of material will be water-permeable, so that a suitable profile can be used without the need for an additional water draining facility, the longitudinal rib being constructed integrally with the sound-damping layer of material to the side of the railway. As well as being used in combination with a steel or concrete foundation bed, the layer of porous, bound material, for example the bituminously bound material with open pores, can also be used on, for example, a foundation bed made of sand, optionally topped with a bed of gravel. Instead of concrete or steel, uses in conjunction with foundation beds made of other solid materials (aluminium, wood, and the like) are also conceivable. As regards the railway, this can be of the type over which the vehicle moves, but also of the type from which the vehicle is suspended. Particularly when using the bituminously bound material, with stone-like chips and an open pore structure, the following advantages can be achieved: the material can easily be adhesively bonded to the foundation bed by means of an asphalt binding layer or similar material; by tailoring the chip size of the stone-like material and the ratio of bituminous binder to fillers, the pore size and pore density can be varied within a wide range, as a result of which the material properties of the sound-damping layer can be adapted to the (sound) conditions; the material is inexpensive; the material can be recycled; a considerable sound reduction is achieved; a number of expedient application techniques are available, which have already proved themselves through long usage in road-building; compaction, as is customary in road-building, is not required, or is required only to a limited extent, and can be achieved by means of a vibrating mechanism instead of road rollers, as are used in road-building. In the text which follows, the invention will be explained in more detail on the basis of a non-limiting exemplary embodiment, with reference to the appended drawing. In the only figure, the drawing shows a view of the profile of a double railway 1 on a foundation, which will be described in more detail. Four rails 2 are depicted; two adjacent rails 2 each for guiding a vehicle 5. The rails 2 lie on a foundation bed 3, in this case made of concrete. This foundation bed 3 is embedded in a bed of sand 4. However, it is also possible for the foundation bed 3 to lie on a piled foundation or the like. The foundation bed 3 can also be part of a bridge. The foundation bed 3 is an essentially compact, continuous slab or plate which is parallel to the rails 2. For example, the foundation bed 3 is composed of a number of prefabricated slab parts or plate parts, made of for example concrete or steel, mounted behind and/or next to one another. The foundation bed 3 is, as depicted, covered with a sound-proofing layer 6 in accordance with the invention. The rails are recessed both into the sound-proofing layer 6 and into the foundation bed 3. The rails 2 may, however, also be recessed exclusively into the sound-proofing layer 6, and thus be located on top of the foundation bed 3. In that case, however, the sound reduction is lower. It is even possible to fit the rails 2 on top of the sound-proofing layer 6, in which case, however, the sound reduction is likewise limited with respect to the embodiment shown in the drawing. To the side of the rails 2, the sound-proofing layer 6 is profiled, and has a longitudinal rib 7. This longitudinal rib 7 can be constructed such that the gap with respect to the underside of the vehicle 5 is narrowed to a certain degree in order in this way to damp the sound still further. Another form of profiling is also possible. The sound-proofing layer 6 can easily be installed using, for example, the mould 8 shown. This mould 8 also possesses a vibrating apparatus, if compaction is necessary to a limited extent. An example of a composition of the layer 6 is as follows: At least 70% by volume, preferably at least 85% by volume of chipped, coarse mineral, preferably fragmented stone, with a diameter (sieve) of approx. 8-11 millimetres or 6.3-8 millimetres; at most 10% by volume, preferably 0% by volume of sand; 4-6% by volume of fillers (for example pigments or limestone); 4-6% by volume of bitumen (preferably rubber-modified). The layer 6 can, for example, have a layer thickness of 10 to 60 millimetres, preferably of 20 to 50 millimetres.

Claims: Railway, wherein the rails (2) are supported by an essentially compact foundation bed (3) made of, for example, concrete or steel, which foundation bed essentially spans at least the width of the vehicle moving along the rails and wherein said foundation bed is covered with a layer of material (6) such that the sound produced by a vehicle moving along the rails is substantially damped, characterised in that the damping material comprises asphalt or asphalt concrete with chips of stone-like material bound by a bituminous binder material and having an open pore structure of at least 10%, preferable at least 20% and defining a longitudinal rib (7) to the side of the rails integrally formed with said layer of damping material. Railway according to claim 1, wherein the rails lie recessed into the layer of damping material. Railway according to claim 2, wherein the rails lie recessed into the foundation bed.

Inventors: HEERKENS JOSEPHUS CORNELIS P, PRONK CORNELIS PIETER, HEERKENS, JOSEPHUS CORNELIS P., PRONK, CORNELIS PIETER
Applicants: HEIJMANS WEGEN EN WATERBOUW B, KONINK WEGENBOUW STEVIN B V, HEIJMANS WEGEN- EN WATERBOUW B.V., KONINKLIJKE WEGENBOUW STEVIN B.V.
Application year: 1996
Main classification: E01B1
IPC codes: E01B19, E01B1, E01B2