A NOISE SUPPRESSION DEVICE FOR RAILWAY TRACKS

Abstract: A noise suppression device for railway tracks extends in a direction in parallel with the longitudinal direction of the track. The device is longitudinally divided into sections which each are movable between a first position in which it extends in a substantially vertical direction close to the building gauge of the track, and a second position in which the section is removed from the vicinity of the building gauge. Each section is completely or partly concealed in its second position. Each section comprises means to move it between the two positions, and these means are adapted to be remote-controlled.

Description: A noise suppression device for railway tracks The invention concerns a noise suppression device for railway tracks. The device extends in a direction in par- allel with the longitudinal direction of the track and is longitudinally divided into sections, each of which is movable between a first position in which it extends in a substantially vertical direction close to the building gauge of the track, and a second position in which the section is removed from the vicinity of the building gauge. Noise from railway traffic is a great environmental prob¬ lem in the industrialized world. Many residential and recreational areas are exposed to an unacceptably high noise load from railways. The noise problem concerns many people, as railway tracks cut through urban areas to a great extent. One of the advantages of the railway is precisely that it enables transport from city centre to city centre. Further, the noise nuisances are aggravated, because the railway traffic takes place round the clock at most places and thus affects sleep and rest. It has been observed in practice that people living close to a railway section must live with a noise load of more than 100 dB (A) when a train passes. The noise load may still be as high as 90 dB (A) at a distance of 100 metres from the railway. It goes without saying that influences of this order may be very unpleasant. Many measures have been proposed to reduce these noise problems. A number of studies have shown that a great part of the noise from railway carriages is emitted from rails, wheel and bogies. The wheel/rail contact creates a great part of this compound noise. Therefore, some local urban railways use rubber wheels to generate less noise. However, this is not possible on "real" railways, one reason being the heavy goods traffic. Various forms of shields or noise skirts mounted around wheels or bogies of trains have also been proposed. An example of this is known e.g. from US Patent Specifica¬ tion No. 1740995. However, this has the drawback that the method works only if all or at any rate most of the ve¬ hicles passing a given railway section are provided with these means. This is impossible in practice, since rail¬ way carriages are used internationally to a great extent, so that it cannot be known beforehand which vehicles will pass a section. Known is also a large number of different measures which are adopted around the railway line itself. A generally known approach is ramparts of different heights depending upon the size of the desired suppression. These ramparts require much space and enormous amounts of earth and thus also planting and subsequent nursing. Ramparts only pro¬ vide shielding outside railway sections, so the effect of these ramparts in case of railway sections with several tracks is very limited. The noise propagates over the most remote rampart without meeting any obstacles on its wa . In those cases where the planners have had wide zones along the railways at their disposal, dense planting has been carried out. This may be combined with ramparts. The results are good only if the belts are wide. The effect diminishes considerably in the winter if the plants are deciduous. Further planting involves huge investment costs and requires much space and subsequent nursing. Also planting boxes in various forms and materials are used as noise shields. These, too, involve high costs, and the noise from multi-track systems cannot be "confined" even by very high boxes. Various forms of board fences have also been used as shields against noise from railways. These have an effect close to the board fence, but, like with several of the other measures, the noise can propagate over the board fence. Steel shields have been used along the railways to a great extent in recent years. These shields vary in height from about 1 to 2 metres. These may have many dif¬ ferent shapes; but a widely used type is shields where horizontal, profiled plates are mounted on steel columns rammed into the ground. Like with several of the other measures, the suppression is just partial, because the noise from the train most remote from the shield passes the shield almost unobstructedly. The height of these shields is limited to the lower edge of the windows in the carriages, which also puts a limit to the effect of the suppression. Also concrete shields or concrete walls are used, whose height may vary from about 1 metre to several metres. Concrete shields are frequently used where noise shield¬ ing of e.g. a residential area is to be carried out on a very limited space. To achieve a noticeable effect, the concrete wall must be very high, and this may give an "enclosed" feeling in the residential area, and in any event there will be no view from the train because of the wall. It is also known to use low shields of concrete or of a similar material which are placed close to the carriages. Further, also centre walls of concrete are known. An ex¬ ample of this is known from European patent application, Publication No. 0237519. Similarly, DE Offenlegungs- schrift No. 3602313 discloses noise suppression which, at station areas, comprises vertical walls which are po¬ sitioned in the vicinity of the railway track itself, and which extend slightly above the lower edge of the ve¬ hicles. Furthermore, UK patent application, GB 2236343, discloses a channel which likewise comprises vertical walls on both sides of a track. The upper edge of these walls is also level with the lower edge of the carriages. Since these shields are positioned much closer to the in¬ dividual railway track, they also gives a smaller "noise opening" than the measures described above. The gap be¬ tween train and shield may be as low as 25-30 cm, the distance being several metres for the bigger shields, frequently as high as 25 or 30 metres. At sections with two or more tracks it is moreover possible to place the shields close to each individual track, thereby improving the suppression in these situations. Although shields of this type provide a quite good sup¬ pression of the noise, they are, however, also vitiated by a number of drawbacks. Thus, shields of this type make repair and maintenance in or at the track difficult or even impossible, and at winter it may be very difficult to carry out snow clearing, since the snow will settle in the box formed by the shields and thus be very difficult to remove. Another drawback of the known shields is that the shields put a limit to particularly wide special transports, which may be a frequent occurrence on many railway sections. Finally, it may be mentioned that pas¬ sengers in a train which has to stop on a section with these shields, will have difficulty in leaving the train. It has been attempted to remedy some of these drawbacks by a noise suppression device known from Austrian Patent Specification No. AT 372 435, where the shields are di- vided into sections which are movable between two posi¬ tions, as they are pivoted about a horizontal axis either toward the track or away from it. This device facilitates repair and maintenance in or at the track, as the sec- tions aligned with the work place may be moved to a posi¬ tion in which they do not interfere with the job. After completion of the job, the sections must be brought back to the noise suppressing position. In case of snow clear¬ ing and wide special transports, this solution requires that staff has been sent out along the track beforehand to move all the sections to the position in which they do not interfere, and subsequently bring them back again. The problem of snow clearing may be remedied partly by making the sections spring-loaded so that they can yield to the snow; but this presupposes that they are not ham¬ pered by snow on the side to which they are to be moved, and this condition will be fulfilled only rarely in prac¬ tice. This device moreover has the serious drawback that when the sections are to be pivoted between the two positions, the area passed by a section during this movement must be free. If a section pivots inwards toward the track, it will pivot into the building gauge, and the movement can then be performed only if it is certain that there is no train in the track. Outward pivotal movement from the track can be used only if there is no other track at the side, since the section will then pivot into the building gauge of said track. Therefore, this solution cannot be used on double track lines. Nor will the solution work if snow or another material is present opposite the section, as the pivotal movement will then be prevented. The invention provides a noise suppression which at least opens up the possibility of the same effect as the men¬ tioned shields arranged close to the track, and which -6- also allows repair and maintenance as well as snow clear¬ ing to be carried out unobstructedly in the same manner as at tracks which are not provided with noise suppres¬ sion. Further, the noise suppression of the invention permits wide special transports, and it will also be pos¬ sible to leave a train unobstructedly like on other rail¬ way sections. The noise suppression may moreover be used without the above-mentioned problems in double track and multi-track railway sections, and it does not interfere with the building gauge of the track when it moves be¬ tween its two extreme positions. This is achieved according to the invention by a device of the type described in the opening paragraph, where each section is completely or partly concealed in its second position. Each section comprises means to move it between the two positions, and these means are adapted to be remote-controlled. This ensures that the noise sup¬ pression, when it is in its active state, enables an ef- feet which corresponds to or is better than the fixed low shields arranged close to the track. However, when needed, the shield may be moved to the concealed posi¬ tion, and then e.g. maintenance jobs may be performed. When the shields are adapted to be remote-controlled, the shields can be "removed" by a single operation on a whole line, e.g. when a wide special transport is to pass the railway line. When, as stated in claim 2, the sections are adapted to move between the two positions in substantially a verti¬ cal direction, it is ensured that they keep clear of the building gauge of the track or possible adjacent tracks during the movement, and the movement will not be pre¬ vented by snow or anything that might be present at the side of the device. This is important in particular when the sections are adapted for remote control, as is the case here. When moreover, as stated in claim 3, the sections may be operated locally, it is ensured that just one or a few shields are to be "removed" locally for minor repairs. When, as stated in claim 4, the concealed position is a state of rest and the movement means are adapted to move the section to this state of rest in case of an error or missing control, it is ensured that the concealed state will be the safe state which the noise suppression auto¬ matically assumes in case of an error, so that it is no longer possible to operate the shields by means of remote control. As stated in claim 5, the sections may moreover be adapted to be placed in intermediate positions, so that the shields may be adjusted to several different heights. This means that the shields may e.g. be lowered so that a wide special transport can pass, while maintaining some noise suppression. The noise suppression may be improved by constructing the surface such that they will suppress noise. This may be done by means of a sound reflecting surface, as stated in claim 6, or by means of a sound ab¬ sorbing surface as stated in claim 7. A preferred embodiment is defined in claim 8 and com¬ prises two columns between which a collapsible shield is arranged. Thus, the shield is just to be collapsed to make it assume the concealed state. A particularly advan¬ tageous embodiment is obtained, as stated in claim 9 , by adapting the collapsible shield to be collapsed and ex¬ tended in a vertical direction. Claim 10 defines a par- ticularly elegant solution where the upper edge of the shield is shaped so as to conceal the rest of the col- lapsible shield in the concealed position. When, as stated in claims 11 and 12, the control columns are moreover adapted to be removable, an even more concealed structure is obtained. The invention will be explained more fully below with reference to the drawing, in which fig. 1 shows how noise suppression according to the in- vention may be employed on a railway line, fig. 2 is a cross-section of an embodiment of the inven¬ tion in an activated state, fig. 3 is a cross-section of an embodiment of the inven¬ tion in a state of rest, fig. 4 is a lateral view of the embodiment of figs. 2 and 3, and figs. 5A-J show alternative embodiments of the invention. Fig. 1 shows a cross-section of a railway line in which rails 1, 2 are laid on sleepers 3 which are in turn laid in ballast 4. The track includes a building gauge 5, which indicates the area where fixed equipment mounted along the railway may not be present. A locomotive 6 run¬ ning on the rails 1, 2 is shown by way of example. It will be seen that the locomotive keeps within the shown building gauge 5. Noise suppression shields 7, 8 are mounted at the side of the track, and each of shields is placed in the ballast 4 by means of foundations 9 , 10. It will be seen that the noise suppression shields 7, 8 are outside the building gauge 5. It will also be seen that the two shields 7, 8 form a "box" around the track, it being difficult to clear snow in the winter if the shields 7, 8 cannot be removed or concealed. Figs. 2, 3 and 4 show in greater detail how a noise sup- pression of the invention may be constructed. A section of the noise suppression 7 consists of a set of guide columns 11, which are connected with a longitudinal box 12 containing a drive motor 13 and a transmission 14. A collapsible shield 15 is suspended between the two guide columns 11, said shield forming the actual noise suppres¬ sion element in the extended state shown in fig. 2. In its collapsed state, as shown in fig. 3, the shield 10 is just about 10 cm high. In the collapsed state, the shield lies on top of the box 12, which, in turn, is placed on the foundation 9. Embodiments are also conceivable wherein the box 12 is recessed so much into the founda¬ tion 9 and the ballast 4 that the collapsed shield is present below rail height. In practice such a noise suppression shield may e.g. be 420 cm long and about 110 cm high measured over the rails. Where the building gauge does not allow this height, e.g. between two tracks on a double track line, a lower shield is used. The foundation 9 may consist of steel profiles which are rammed into the ground and whose upper end is secured laterally by means of steel profiles secured to the lower edges of the rail. These foundations must be mounted very precisely, and since they are to transfer big forces, the requirements to be satisfied in this job will be quite great. The upper end of each foundation will have thereon a mounting shoe permitting very quick mounting of the elements, and exchange of a damaged element can take place just as quickly. The guide columns 11 are dimensioned for the loads from high speed trains. They contain e.g. a chain drive which can raise and lower the shield. Other mechanisms are also conceivable for this purpose, e.g. spindles, hydraulics, pneumatics, racks, wires and the like. The control col¬ umns may either be stationary, or they may be adapted to be lowered or put down. The shield itself consists of a suitable number of steel slats which are hinged together. In the extended state, the slats constitute a strong unit whose strength may be compared to the known steel profile plates. A pin is se¬ cured at the ends of each slat and serves to transfer the load from the shield to the columns. The pins also form part of the raising and lowering mechanism. To increase the noise suppressing effect of the shields, the steel slats may be treated with a soft surface coat¬ ing having a sound absorbing effect. For example, a rub- ber material or the like, e.g. pulverized used car tires, may be used. The surface may also be shaped so that it has a sound reflecting effect and reflects the sound in a desired direction. The motor 13 with associated transmission 14 is mounted in the box 12, as mentioned. The motor 13 may be a rela¬ tively small electric motor. A motor of modest size may be used, because it has no importance whether the trans¬ mission is to be very big. It does not matter whether it takes several minutes to lower or raise a shield. As men¬ tioned, e.g. hydraulics, pneumatics or the like may be used as alternatives to small electric motors. A large number of connected elements (e.g. up to 50 or 100) may be coupled together electrically by means of plugs be- tween the individual elements, so that they may be re¬ mote-controlled as an assembled unit. In addition, each section may be operated manually on the spot, which will be required, e.g. when maintenance work is performed on the track. Sound calculations have shown that the shield described can reduce the noise load from most train types by at least 10 dB (A) . Such a reduction in noise may be re¬ garded as a considerable reduction, because it corre¬ sponds to halving the subjective perception of sound. Figs. 5A-J show a plurality of alternative embodiments of a noise suppression shield of the invention. Fig. 5A shows an inverse "roll-up door", which is pulled up between two guide columns which correspond to the col¬ umns in the embodiment described above. The modular length of this embodiment may also be of the same order as the one described above. Fig. 5B shows a solution similar to fig. 5A, but turned up side down that the "door" is protected against the weather in a box, which may optionally also be movable in a vertical direction. Fig. 5C shows a solution using steel elements with hinges which only have a height of 5-8 cm in the recessed posi¬ tion. Fig. 5D shows long U-shaped steel panels which may be lowered telescopically right down to ground level. The modular length is 4-5 metres. Fig. 5E also shows 4-5 metre long "planks", which are automatically stacked horizontally when snow clearing or work on the rails is necessary, but which form a shield, as described before, when they are stacked vertically. Fig. 5F shows a corre¬ sponding solution, but since the structure will be weaker, the length of the modules will be correspondingly shorter. Fig. 5G is again a "plank solution", and the elements are stored horizontally here when they are not in use. Figs. 5H and I show a solution using a combination of air cushions and horizontal steel braces. The system may be a low-pressure air system which, like an inflated mini- hall, may be kept up by a small ventilator. The system is shown in the active, i.e. sound absorbing position in fig. 5H, while it is shown in the collapsed or "punctured" version in fig. 51. Finally, fig. 5J shows a version with the same basic idea as figs. 5H and I. Here, the broad shape is contemplated as a reinforcement, which makes the vertical columns unnecessary.

Claims: P a t e n t C l a i m s 1. A noise suppression device for railway tracks, said device extending in a direction in parallel with the lon¬ gitudinal direction of the track and being longitudinally divided into sections, each of which is movable between a first position in which it extends in a substantially vertical direction close to the building gauge of the track, and a second position in which the section is re¬ moved from the vicinity of building gauge, c h a r a c ¬ t e r i z e d in that each section is completely or partly concealed in its second position, that each sec¬ tion comprises means to move it between the two posi- tions, and that these means are adapted to be remote-con¬ trolled. 2. A device according to claim 1, c h a r a c t e r ¬ i z e d in that it is adapted to move between the two positions in a substantially vertical direction. 3. A device according to claims 1 or 2, c h a r a c ¬ t e r i z e d in that said means for moving a section between the two positions may moreover be operated lo- cally. 4. A device according to claims 1-3, c h a r a c t e r ¬ i z e d in that said second position is a state of rest, and that said means are adapted to move the section to this state in case of an error or missing control. 5. A device according to claims 1-4, c h a r a c t e r ¬ i z e d in that each section may moreover be placed in positions which are present between the said two posi- tions. 6. A device according to claims 1-5, c h a r a c t e r ¬ i z e d in that the device comprises a sound reflecting surface. 7. A device according to claims 1-5, c h a r a c t e r ¬ i z e d in that the device comprises a sound absorbing surface. 8. A device according to claims 1-7, c h a r a c t e r - i z e d in that each section comprises two guide columns arranged at their respective ends of the section and a collapsible shield arranged between the columns. 9. A device according to claim 8, c h a r a c t e r - i z e d in that the collapsible shield is adapted to be collapsed and extended in a vertical direction. 10. A device according to claim 9, c h a r a c t e r ¬ i z e d in that, at its upper edge, the collapsible shield has a cover which conceals the rest of the col¬ lapsible shield in said second position. 11. A device according to claims 8-10, c h a r a c ¬ t e r i z e d in that, in the position in which the sec- tion is completely or partly concealed, the guide columns are adapted to be moved between a vertical and a horizon¬ tal position. 12. A device according to claims 8-10, c h a r a c - t e r i z e d in that in the position in which the sec¬ tion is completely or partly concealed, the guide columns are adapted to be moved downwards in a vertical direction to a position completely or partly below ground level.

Inventors: DALGAARD ALLAN, DALGAARD, ALLAN
Applicants: CARL BRO ANLAEG A S, DALGAARD ALLAN, CARL BRO ANLAEG A/S, DALGAARD, ALLAN
Application year: 1995
Main classification: E01B19
IPC codes: E01B19, E01F8, E01F13