A NOISE-ABSORBENT AND/OR -REDUCING SCREEN

Abstract: A noise-absorbent and/or -reducing screen (1) intended for being erected along a line that is heavily exposed to noise, e.g. road, and comprising a relatively flat first wall element (10) that has a front side (11) and a back side and that is made of a noise-absorbent and/or -reducing material; a second wall element (20) that extends parallel with the first wall element (10) and is arranged in front of said front side (11); said second wall element (20) being configured for carrying vegetation (7). The invention is characterised in that the second wall element (20) is configured as a frame with pairs of opposed frame elements that define the outer periphery of the frame; said frame also comprising a number of interior parallel rod elements (30) that extend between two opposed frame elements and having a front and a back side that face towards the first element (10); and that the second wall element (20) comprises a structure of approximately parallel, cut-off branches or stems (40) of a naturally occurring growth; said branches or stems (40) extending between opposed frame elements and alternatingly on the front and back sides of the rod elements (30) in order to thereby be secured to the frame.

Description: A noise-absorbent and/or -reducing screen The present invention relates to a noise-absorbent and/or -reducing noise abatement screen intended for being erected along a line that is heavily exposed to noise, for instance a road, and comprising a relatively fiat, first wall element with a front and a back side, and made of a noise-absorbent and/or -reducing material; a second wall element that extends parallel with the first wall element and arranged in front of said front side, said second wall element being configured for being able to carry a vegetation mantle. WO 99/22075 and WO 94/03679 teach examples of such screens where the visible faces are constituted of naturally growing vegetation. The first- mentioned solution is inconvenient in that damage to one of the willow tree stems may require replacement of the stem to ensure a uniform appearance of the screen. The second solution requires cumbersome mounting of a steel grid and in certain cases the metal grid may render the growth conditions to the vegetation more difficult. It is the object of the invention to pr vide a screen that can be manufactured in a more simple way than the known screens and that provides improved growth facilities for vegetation that is to serve to cover the screen and thereby ensure an aesthetic appearance of that screen. This is obtained by configuring the screen as featured in the characterised part of claim 1. By the solution thus suggested, improved growth conditions for climbing/creeping vegetation is obtained, the one wall element being able to protect the vegetation from the influences of wind, while the second wall element is used as growth support. By use of a growth support in the form of relatively straight, cut-off stems or branches that extend as featured in claim 1 , it be- comes possible to fixate the branches or the stems in a simple manner while simultaneously the vegetation is able to penetrate between the individual branches or stems and seek partial shadow and be sheltered from the wind in the space between the one wall element and the second, behind the branches or the stems. This is particularly important when the vegetation is exposed to heavy sunlight since, in this manner, the evaporation of water can be reduced. Simultaneously the use of branches or stems protects the growth support of the vegetation against excessive temperatures and thus also against scorching. If a metallic support face for the vegetation were to be used instead of branches or stems, as taught in WO 94/03679, the temperature of the growth support might become very elevated with an ensuing adverse effect on the vegetation. Furthermore the use of branches or stems imposes a reduced load on the environment. The screen according to the invention is particularly suitable for being used in connection with ivy that is a very fast-growing and evergreen plant. It has thus been found that, over time, ivy will not only form a dense coating of the branches or the stems, which is desirable ia if the stems or the branches are in time discoloured, but also that ivy is able to increase the longevity of the branches or the stems by delaying or inhibiting the putrefaction process by absorbing liquid. Preferably, the first wall element is being defined by or includes batts of mineral wool, as stated in claim 4. One advantage involved in such a construc- tion is that the need for separate protective means covering and protecting the wall element against rainwater is obviated. Configuration of the screen as featured in claim 5 makes it possible for the vegetation to root in the batt, the wall element absorbing rainwater. The wall element that comprises the branches or the stems is configured as a frame with opposed frame elements that can, by the embodiments featured in claims 6 and 7, be secured directly to a base construction for the screen, e.g. a foundation, or that can be secured to columns that are mounted in ad- vance on the site of erection of the screen. In particular by the latter solution, it is preferred, as featured in claim 9, that the dimensions of the frame can be adjusted, whereby the frame can be adapted to minor variations in the distance between the columns. By arranging the stems or the branches as featured in claim 11 , they contribute to ensure resistance to deformation of the wall element, since impacts are avoided that would seek to deform the frame. Besides, the screen may also particularly advantageously be configured as featured in claims 12-14, whereby it is possible to achieve further improved growth conditions for a climbing/creeping vegetation, such as ivy. In the following, the invention will be explained in further detail with reference to a preferred embodiment. Figure 1 shows an exploded view of a screen according to the invention, consisting of a total of four wall elements; Figure 2 shows the screen shown in Figure 1 , seen in a front view; Figure 3 shows the screen shown in Figure 1 , seen in a schematical cross- sectional view from the side; and Figures 4-6 show alternative embodiments of the one wall element. Figure 1 shows an embodiment of a screen 1 comprising two vertical panel/plate-like wall elements 10 that are noise-absorbent and/or -reducing and of a first type, whose surface areas abut on each other. In the example, the wall elements 10 consist of batts of rock wool and have a height of pref- erably 2-4 meters and a total width of preferably 2-4 meters. In front of each wall element 10, the screen 1 also comprises a respective wall element 20 of a second type that serves to carry vegetation. The wall elements 10, 20 are connected to each other via a number of connecting means 5, such as bolts or screws, that extend perpendicular through the surfaces of the wall ele- ments 10,20. Depending on the circumstances the screen 1 according to the invention may comprise one single wall element 10 of the first type, whose front side 11 faces towards a single wall element 20 of the second type. It will be understood that the screen 1 is rarely mounted alone as shown in Figure 1 , but rather in combination with a number of corresponding screens 1 that are arranged in extension of each other for forming an elongate face where all the wall elements 20 of the second type are visible. The screens are typically erected along a road line that is heavily exposed to noise. The wall element 20 of the second type is configured as a rectangular, rigid frame with vertical, opposed frame elements 22,24 that are connected by horizontal frame elements 26,28 for forming the outer periphery of the frame. Preferably the frame elements 22,24 have a somewhat larger dimension than the horizontal frame elements 26,28. The wall element 20 is shown in further detail in Figure 2, and it will appear that the vertical frame elements 22,24 have extended portions 23,25 that are introduced in holes in the soil 2 that are formed in advance. The frame elements 22,24 that may advantageously be formed from timber or metal preferably serve to transmit the weight of the screen 1 to the base construction of the screen 1 that may alternatively be a foundation block of e.g. concrete to which the frame elements 22 are secured. The remaining parts of the frame can be made of metal. Besides, the frame comprises a number of rod elements 30 that are connected to the vertical frame elements 22,24 and that extend parallel with the horizontal frame elements 26,28. In the shown example the frame comprises four rod elements 30 that are arranged at the same distance from each other. To carry a creeping/climbing plant 7, such as ivy, that is planted in the soil 2 immediately in front of the screen 1 , the frame comprises a braided structure of cut-off branches or stems 40 of willows wood that extend upwards along the expanse of the vertical frame elements 22,24. Relatively straight branches or stems 40 are selected that can be arranged next to each other in the entire width of the frame. In order to secure the branches or the stems 40 to the frame it is usually sufficient to merely braid the same alternatingly to the front and back sides of the rod elements 30 as shown in Figure 3. By the back side of the rod elements 30 is to be understood the side that faces towards the front side 11 of the wall element 10, whereas the front side of the rod elements 30 faces in the opposite direction. It is also preferred that neighbouring branches or stems 40 are mounted in accordance with the re- verse pattern, as outlined by the dotted line in Figure 3, whereby the one stem or branch abuts on the front side of a rod element 30, whereas the second abuts on the back side of the rod element 30. Hereby a uniform, open structure is obtained, whereby the vegetation 7 is able to climb on the outside of the branches or the stems and attach in areas between the wall element 10 and the rod elements 30, behind the branches or the stems 40. Besides, such arrangement imparts to the frame a resistance to deformation, since the forces generated by the slightly flexed neighbouring stems or branches 40 will, on a given rod element 30, be oppositely oriented. The rod elements 30 may be made of steel, timber, plastic or the like. Now, Figure 4 shows an alternative embodiment of the wall element 20, wherein the frame constitutes a separate component with vertical frame elements 35,38 and horizontal frame elements 26,28 that form the outer periph- ery of the frame, and with rod elements 30 that extend between the vertical frame elements 35,38. In combination with columns 22,24 the frame forms the wall element 20. The shown frame can advantageously be delivered from the manufacturer with the stems or branches 40 mounted thereon, the frame not being attached to the columns 22,24 until on the site of use as such for the screen 1 ; e.g. by screwing. The frame shown in Figure 4 is particular in that the rod elements 30 as well as the horizontal frame elements 26,28 are telescopic, whereby the frame dimensions can be adjusted slightly. This is practical, in particular when the frame is to be mounted on columns 22,24 that are already arranged on the site of use, since small inaccuracies in the distance between the columns 22,24 may thereby be taken into account. The ability to be telescopic is obtained in that the horizontally extending elements 26,28,30 of the frame comprise a tap 70 mounted on the one frame element 35 and a tubular element 80 that is mounted on the second frame element 38 and that is able to receive the tap 70. The distance between the frame ele- ments 35, 38 can hereby be varied slightly, e.g. within an range of 1-10 cm, preferably 2-3 cm, as shown at the bottom of Figure 4. By the alternative solution shown in figure 5, the frame elements 26,28 and the rod elements 30 have been extended relative to the vertical frame ele- ments 35,38 and thereby form tap-shaped protrusions 39 that are introduced into openings 21 formed in the columns 22,24. This solution is suitable for absorbing tolerances in the distance between the foundation for the columns 22,24 and is useful when the wall element 20 consisting of the columns and the frame area are assembled prior to attachment to the foundation. Finally, Figure 6 shows a solution in which two steel columns 22', 24' form a delimitation for not shown rock wool batts that form the first wall element 10. The columns 22', 24' may optionally be anchored to the base construction, including to the ground 2 via a foundation. The frame that carries the branches or the stems 40 has vertical frame elements 35,38 that can advantageously be secured by welding to the columns 22', 24'. It is noted that the first wall element 10 may very well be manufactured of glass or concrete or it may be a longboard construction that provides the intended noise-absorbent or -reducing effect. What is important is merely that the first element 10 has an expanse that corresponds essentially to the expanse of the second element 20. The term 'relatively flat' as used in claim 1 is thus intended to designate a construction that primarily complies with this condition and whose shape is preferably substantially panel/plate-like. Moreover, the density of the mineral fiber batts used for the first wall element 10 may lie between 25 and 450 kg/m 3 , preferably in the range of 40 to 200 kg/m 3 . The batts may be layered, the layers optionally being arranged such that a central layer has a low density whilst two or more coplanar layers have a higher density. The further coplanar layers may be arranged such that layers most distant from the central layer have the highest density. Preferably, the mean density of the mineral fiber batt is between 80 and 150 kg/m 3 , most preferably between 100 and 150 kg/m 3 . The thickness of the mineral fiber batt is preferably between 10 and 40 cm. A high noise reduction is achieved when the mineral fiber batt weight per unit surface area lies between 15 and 40 kg/m 2 , preferably between 20 and 25 kg/m 2 . The exposed surface of the wall element 10 may be defined by a surface layer providing protection against the weather and mechanical forces, the layer preferably being defined by a fibrous web, e.g. a glass fiber web.

Claims: C l a i m s 1. A noise-absorbent and/or -reducing screen (1 ) intended for being erected along a line that is heavily exposed to noise, e.g. a road, and comprising: - a relatively flat, first wall element (10) that has a front side (11 ) and a back side and that is made of a noise-absorbent and/or -reducing material; - a second wall element (20) that extends parallel with the first wall ele- ment (10) and is arranged in front of said front side (11 ); - said second wall element (20) being configured for carrying vegetation (7); characterised in - that the second wall element (20) is configured as a frame with pairs of opposed frame elements (22,24; 35,38; 26; 28) that define the outer periphery of the frame, - said frame also comprising a number of interior parallel rod elements (30) that extend between two opposed frame elements (22,24; 35,38; 26,28) and having a front side and a back side that faces towards the first element (10); and - that the second wall element (20) comprises a structure of approximately parallel, cut-off branches or stems (40) of a naturally occurring growth, - said branches or stems (40) extending between opposed frame elements (22,24; 35,38; 26,28) and alternatingly on the front and back sides of the rod elements (30) in order to thereby be secured to the frame. 2. A noise-absorbent and/or -reducing screen according to the preceding claim, characterised in that the first wall element (10) is manufactured from a fibrous material. 3. A noise-absorbent and/or reducing screen according to any one of the preceding claims, characterised in that the first wall element (10) is formed from a substantially plane board. 4. A noise-absorbent and/or -reducing screen according to any one of the preceding claims, characterised in that the first wall element (10) is manufactured from mineral wool, preferably rock wool or glass wool. 5. A noise-absorbent and/or -reducing screen according to any one of the preceding claims, characterised in that the first wall element (10) is manufactured from a water-absorbing material. 6. A noise-absorbent and/or -reducing screen according to any one of the preceding claims, characterised in that two of the frame elements (22,24) comprise means for securing the screen (1 ) to a base construction for the screen. 7. A noise-absorbent and/or -reducing screen according to the preceding claim, characterised in that said means are constituted by an extension (23,25) of the frame elements (22,24) that is intended for being secured in a foundation structure. 8. A noise-absorbent and/or -reducing screen according to any one of the preceding claims, characterised in that means (5) for securing the first wall element (10) relative to the second wall element (20) engage with the frame elements (22,24; 35,38; 26,28). 9. A noise-absorbent and/or -reducing screen according to any one of the preceding claims, characterised in that the length of the rod elements (30) and at least two opposed frame elements (22,24; 35,38; 26,28) are adjustable. 10. A noise-absorbent and/or -reducing screen according to the preceding claim, characterised in that the rod elements (30) are telescopic. 11. A noise-absorbent and/or -reducing screen according to the preceding claim, characterised in that two adjoining branches or stems (40) are arranged so as to extend at the front and back sides, respectively, of a given rod element (30) in order to thereby impart to the frame a high degree of resistance to deformation. 12. A noise-absorbent and/or -reducing screen according to any one of the preceding claims, characterised in that the branches or stems (40) have a thickness of between 0,7 and 2,5 cm, preferably between 1 ,0 and 2,0 cm, most preferably between 1 ,2 and 1 ,5 cm; and that the distance between two adjoining rod elements (30) is between 0,3 cm and 0,6 cm. 13. A noise-absorbent and/or -reducing screen according to any one of the preceding claims, characterised in that the branches or stems (40) have a length of between 1 ,0 and 3.5 m, preferably between 1 ,0 and 3,0 m, most preferably between 1 ,0 and 2,5 m; and that the second wall element (20) includes between 50 and 150, preferably between 70 and 100, most preferably between 80 and 90 branches or stems (40) per running meter. 14. A noise-absorbent and/or -reducing screen according to any one of the preceding claims, characterised in that the branches or stems (40) are of one of the following kinds of wood: birch, poplar, hazel, willow.

Inventors: ANDERSEN CLAUS VOIGT, FALK JOHANNES, ANDERSEN, CLAUS, VOIGT, FALK, JOHANNES
Applicants: ANDERSEN CLAUS VOIGT, FALK JOHANNES, ROCKWOOL INT, ANDERSEN, CLAUS, VOIGT, FALK, JOHANNES, ROCKWOOL INTERNATIONAL A/S
Application year: 2001
Main classification: E01F8
IPC codes: E01F8, E04B1