Noise barrier

Abstract: A noise barrier includes upright-standing support columns (2) spaced a predetermine distance from each other and each made of an H section, wall panels being stacked one on another to form a main soundproof wall (1), and a noise control module to be installed on the topmost wall panel comprising first and second additional screens (3,4) installed pivotably (5) to mount frame (11). A coupling member (7,8) holding the first and second additional screens (9,10) at a predetermined angle of inclination when the additional screens are inclined toward and away from a noise source, respectively.

Description: The present invention relates to a noise barrier to control or attenuate undesired sounds or noises coming from streets and highways, railways, factories, etc. Conventionally, to attenuate noises from streets and highways, railways, factories or the like, various wall types of noise barrier are prevalently used to block noises from coming directly from such noise sources. This is because the wall-type noise barrier structures are of relatively low cost while working as effectively as various other noise control modalities. Among the noise control structures, upright or vertical straight wall types of noise barriers are used most widely because they show a high effect of noise control for their relatively low costs and are widely applicable for controlling noises from various sources. For a higher effect of noise control, the vertical straight wall type noise barriers have to be taller. However, such taller ones are correspondingly more expensive (the taller the wall, the greater construction costs they need). In addition, the taller walls have many other disadvantages such as interception of sunlight, obstruction of view (shut-off of prospect), oppressive sensation or claustrophobia, ill ventilation, radio interference or jamming, turbulent flow, wind load, etc. Using such a vertical straight wall type noise barrier only will not be a satisfactory solution to the noise-control problem in some cases. For an improved noise control, it has been proposed to use various other types of noise barriers including bent-top types of which the wall top portion is bent toward the noise source and curved-top types of which the wall top portion is curved toward the noise source. However, it has also been known that use of a noise barrier of such a bent- or curved-top type will make the above-mentioned problems more serious. The recent drastic increase of traffic and higher speed capability of vehicles have resulted in serious environmental noise problems. Since no other effective noise control solutions have been available, the noise barriers of the vertical straight wall type of 3 m, 7 m and 10 m in height and also the above-mentioned bent-top and curved-top types of noise barriers, are used. However, the above-mentioned environmental problems still remain unsolved. The above conventional noise barriers can only provide an improved effect of noise attenuation for an increased wall height. Generally, at a place (about 20 meters) separate from the noise barrier, an increase by 1 m in height of the wall only results in a noise attenuation of about 1 dB. To attain a higher effect of noise control without increasing the wall height, a noise barrier structure has been proposed which has a generally Y-type cross section, Y-type being formed by a main soundproof wall and two additional top screens provided on top of the main body which define an upward opening between them. The noise control or attenuation by this Y-type noise barrier was evaluated by measuring noise level at a place behind the barrier when viewed from a noise source. Also a noise barrier of a vertical straight wall type as tall as the Y-type one was evaluated concerning its effect of noise attenuation. Thus, the noise attenuation (measured sound levels) by the Y-type barrier was compared with that by the vertical straight wall type noise barrier. The comparison proved that the Y-type noise barrier was rather greater in effect of noise attenuation than the vertical straight wall type one. Also, a noise barrier having a limited height and showing an increased effect of noise attenuation is known from the disclosure in the Japanese Patent Application laid open as a Provisional Publication No. 85921/96. This conventional noise barrier is essentially composed of a main soundproof wall body which extends upright from the ground, and first and second additional screens provided on the top of the main wall body, the first additional screen being inclined toward a noise source while the second one is inclined away from the noise source. The first and second additional screens are provided thereon with further additional screens, respectively directed in different directions from those of the first and second additional screens. When this noise barrier structure is viewed from its lateral end, it looks like the horns of a caribou, and this noise barrier is called caribou-horn type. The caribou horn-type noise barrier structure can attenuate noise more effectively than the upright straight wall type and top-bent or -curved type noise barriers on the assumption that they have the same height The Y-type and caribou horn-type noise barriers can attenuate noise effectively with no increase of their height. Because of their complicated geometry such as their open-top design, however, these noise barriers are difficult to transport and install. Even if the additional screens are adapted for installation on the top of the upright straight main wall body at site, the members included in these noise barriers need a wide space for storage and transport, which will lead to a poor efficiency of installation and a greater total cost. Attention is also drawn to JP-09-264009A, which discloses the preamble of the amended claim 1; and to GB-A-2310445. The present invention has an object to overcome the above-mentioned drawbacks of the prior art by providing a noise barrier capable of attenuating noise with an improved effectiveness and without any increase of its height, and designed for the necessity of no large space for storage and transport, which leads to a low cost. The present invention provides a noise barrier including upright-standing support columns spaced a predetermined distance from each other and each made of an H section, and a plurality of wall panels provided between two neighbouring ones of the support columns by inserting each wall panel at opposite lateral edges thereof from above into U-shaped recesses, opposite to each other, of the support columns, the plurality of wall panels being thus stacked one on another to form a main soundproof wall, and a noise control module to be installed on the topmost wall panel, the noise control module comprising: side frame members to be inserted at lower ends thereof from above into the upper portions of the U-shaped recesses, opposite to each other, of the support columns; a lower frame member connecting the side frame members to each other by securing them at lower ends thereof to the lower frame member; first and second additional screens installed at lower ends thereof pivotably to the lower frame member and having a horizontal length smaller than the distance between the support columns; a coupling member holding the first and second additional screens at a predetermined angle of inclination when the additional screens are inclined toward and away from a noise source, respectively; and elastic sound insulation joint sheets bridging, over the support column, said two additional screens put in neighbouring relationship when they are opened away from each other; and characterized in that the coupling member includes at least two arms each installed at one end thereof pivotably to upper portions of the first and second additional screens, respectively, and at the other end thereof pivotably and vertically slidably to at least one of the side frame members. The invention will be further described with reference to the accompanying drawings, in which FIG. 1 is a schematic front view of an embodiment of a noise barrier according to the present invention; FIG. 2 is a side elevation of the noise control module of the noise barrier in FIG. 1; FIG. 3 is a side elevation of the folded noise control module in FIG. 2; FIG. 4 is a front view of the folded noise control module in FIG. 2; FIG. 5 is a side elevation of the noise control module being opened from the folded position; FIG. 6 is a front view of a sound insulation joint sheet used in the noise control module in FIG. 2; FIG. 7 is a sectional view of the sound insulation joint sheet in horizontal position; and FIG. 8 is a graph showing the measured noise control by an upright straight wall type noise barrier and caribou-horn type noise barriers including three types: respectively with no clearance, a clearance of 5 cm and a clearance of 10 cm under the additional screen. FIG. 1 is a schematic front view, from a noise source, of an embodiment of the noise barrier according to the present invention. In this case, the noise source is a highway, for example. As shown, the noise barrier comprises support columns 41 made of an H section and erected at predetermined intervals, and a main soundproof wall 43 formed from a plurality of wall panels 42 provided between two neighboring ones of the support columns 41 by inserting each wall panel 42 at opposite lateral ends thereof from above into U-shaped recesses, opposite to each other, of the support columns 41. The pluralities of wall panels 42 are thus stacked one on another to form the main wall 43. The noise barrier according to the third embodiment further comprises noise control modules 50 (see FIG. 2) each having side frame members 51 and installed on the topmost wall panel 42 by inserting the side frame members 51 at lower ends thereof from above into the upper portions of the U-shaped recesses 41A, opposite to each other, of the support columns 41. The neighboring noise control modules 50 are coupled to each other with sound insulation joint sheets 44 over the support columns 41, as will be seen from FIG. 1. FIG. 2 is a side elevation of the noise control module of the noise barrier in FIG. 1. The noise control module 50 comprises side frame members 51 (one of which is shown for the simplicity of illustration) to be inserted into, and secured in, U-shaped recesses 41A of the support columns 41, a lower frame member 52 connecting the side frame members 51 at the lower ends thereof to each other, first and second additional screens 50A and 50B installed at lower ends thereof pivotably to the lower frame member 52, and a coupling member 55 which holds the first and second additional screens 50A and 50B at predetermined angles of inclination when they are opened to incline toward and away from a noise source. The coupling member 55 consists of two arms 55A and 55B installed at one end thereof pivotably to the upper portions, respectively, of the first and second additional screens 50A and 50B, and at the other end thereof pivotably and vertically slidably to the side frame member 51. Advantageously, the arms 55A and 55B of the coupling member 55 can positively hold the first and second additional screens 50A and 50B in their opened positions. In the embodiment of the noise control module 50 shown in FIG. 2, the first and second additional screens 50A and 50B have provided on the inner surfaces thereof first and second further additional screens 50C and 50D that rise from the inner surfaces of the additional screens 50A and 50B and define a V-shaped space between them and the first and second additional screens 50A and 50B, respectively. The first and second further additional screens 50C and 50D are secured at one end thereof pivotably to the inner surfaces of the first and second additional screens 50A and 50B, respectively, and at the other ends thereof pivotably to the arms 55A and 55B, respectively, forming together a coupling member 55 to be slidable longitudinally of the arms 55A and 55B. There is provided between the lower frame member 52 and lower end of the first additional screen 50A a clearance d that allows the first additional screen 50A to be freely pivotable. The additional screens 50A and 50B are installed to the lower frame member 52 as in the following. Namely, a bracket 59 is fixed to the lower frame member 52, and pivots 63 and 64 are used to connect the bracket 59 to fixtures 61 and 62, respectively, extending from the lower ends, respectively, of the first and second additional screens 50A and 50B. The pivots 63 and 64 may be bolts and fastened with nuts with the first and second additional screens 50A and 50B kept open as shown in FIG. 2. The side frame member 51 has formed therein a vertical slot 51A in which a joint piece 55C is provided to be movable along the slot 51A. The arms 55A and 55B are fixed at the other ends thereof pivotably to the joint piece 55C. The other ends of the arms 55A and 55B may be provided each with a bolt for pivoting thereof. For immobilizing the arms 55A and 55B, the bolt at the other end thereof may be fastened with a nut. Also the joint piece 55C is provided with a bolt for engagement in the slot 51A. For immobilizing the joint piece 55C, the bolt is fastened with a nut to the side frame member 51. The arms 55A and 55B are installed at one end thereof pivotably with bolts to brackets 65 and 66, respectively, provided on the first and second additional screens 50A and 50B. In the status shown in FIG. 2, the nuts are fastened to secure the arms 55A and 55B at one end thereof to the brackets 65 and 66. The arms 55A and 55B have formed therein slots 55a and 55b, respectively, in which the first and second further additional screens 50C and 50D are installed at the other end thereof pivotably and slidably. A bolt is inserted through each of the slots 55a and 55b, and provided with a nut at the other end thereof. In the status shown in FIG. 2, the nut is fastened to secure the further additional screens 50C and 50D at the upper portions thereof to the arms 55A and 55B, respectively. After the additional screens 50A and 50B are fixed with each of the pivotable portions locked, a fixing member 60 shown in FIG. 2 is to be provided to connect the side frame member 51 and upper ends of the additional screens 50A and 50B. Further, a sound absorbing member 50E is provided at predetermined places such as on the additional screens 50A and 50B, and further additional screens 50C and 50D. FIG. 3 is a side elevation of the noise control module 50, showing it in the folded position. The arms 55A and 55B, additional screens 50A and 50B, and further additional screens 50C and 50D are all folded to be parallel to the side frame member 51. A retainer 50F is provided to hold these screens in their folded or closed positions. FIG. 4 is a front view of the folded noise control module 50 in FIG. 3. As seen, each of the additional screens 50A and 50B includes eight screen panels P 1 to P 8 joined laterally to each other by vertical frames 67 and horizontal frames 68 and joined at the intermediate portions thereof to each other by a vertical joint frame 69. Brackets 59 are provided at three places, namely, at opposite ends and middle of the lower frame member 52. Each of the brackets 59 is formed to have a generally U shape. The fixtures 61 and 62 are also formed to have a generally U shape. A hoisting ring 51B is provided on the top of each side frame member 51. For installing the noise control module 50 to the top of the main soundproof wall 43, it is lifted with the hoisting ring 51B caught by a hook at the end of a hoisting wire of the crane, and lowered until the side frame members 51 of the module 50 are fitted into the U-shaped recess 41A (see FIG. 1) of the support column 41 of H section. FIG. 5 is a side elevation of the noise control module 50 being opened from the folded position in FIG. 3. The joint piece 55C is gradually lifted while the arms 55A and 55B are going to be parallel to the joint piece 55C being elevated. Also the further additional screens 50C and 50D are going to rise little by little. FIG. 6 is a front view of the sound insulation joint sheet 44 used in the noise control module 50, showing in detail the additional screens 50A (50B) neighboring each other when they are opened, being connected to each other by the joint sheet 44 bridging over the support column 41. The sound insulation joint sheet 44 may be desirably made of a synthetic rubber such as EPDM (= ethylene propylene terpolymer), CSM (= chlorosulfonated polyethylene) or the like. It is waved for horizontal expansion and shrinkage in the plane of the drawing. FIG. 7 is a cross-sectional view of the sound insulation joint sheet 44. The sound insulation joint sheet 44 is fixed at both ends thereof inside the additional screens 50A and 50B. The joint sheet 44 is provided at opposite ends thereof with fixing plates 44A, respectively, which are to be fixed inside the additional screen 50A (50B). The fixing plates 44A should desirably be made of aluminium, steel or the like. The vertical size of the clearance d shown in FIG. 4 should be 5% or less of the vertical length of the additional screen 50A, which will not adversely affect the noise control of the noise barrier. The clearance d prevents dust or rain from staying in a space defined between the additional screens 50A and 50B. In this embodiment, the clearance d is provided below the additional screen 50A nearer to the road or noise source and not at the opposite side. Alternatively, the clearance d may be defined under the additional screen 50B (at the opposite side of the noise barrier to the noise source) but not at the side nearer to the noise source. The sound insulation joint sheet 44 is waved and elastic at the middle thereof to accommodate irregular gaps between the additional screens 50A (as well as between the additional screens 50B). FIG. 8 is a graph showing the relationship between sound frequencies and noise control by caribou-horn type noise barriers of 5 m in height and having no clearance d , a clearance d of 5 cm and a clearance d of 10 cm, under the additional screen 50A, and by a conventional upright straight wall type noise barrier of 5 m in height. In this experiment, a sound source was placed at a position of 5 m from the noise barrier, and a microphone was placed at a position of 10 m from the noise barrier and at a height of 1.2 m from the ground. As seen from this graph, the effect of noise attenuation by the three caribouhorn types of noise barrier is almost the same irrespectively of the existence and size of the clearance d . Also it will be seen that the noise barrier of the upright straight wall type is lower in effect of noise attenuation than the caribou-horn type noise barriers. In the embodiment having been described in the foregoing, the upright-standing support columns each made of an H section are erected at a predetermined distance from each other. The plurality of wall panels is provided between two neighboring ones of the support columns by inserting each wall panel at opposite lateral ends thereof from above into U-shaped recesses, opposite to each other, of the support columns. The plurality of wall panels is thus stacked one on another to form the main soundproof wall, and the noise control modules are installed on the topmost wall panel by inserting the side frame members at lower ends thereof from above into the upper portions of the U-shaped recesses, opposite to each other, of the support columns. The noise control module further comprises a lower frame member connecting the side frame members to each other by securing the side frame members at lower ends thereof to the lower frame member; first and second additional screens installed at lower ends thereof pivotably to the lower frame member and having a horizontal length smaller than the distance between the support columns; a coupling member holding the first and second additional screens at a predetermined angle of inclination when the additional screens are inclined toward and away from a noise source, respectively; and sound insulation joint sheets elastically extensible horizontally and bridging, over the support column, two additional screens put in neighboring relationship when the first and second additional screens are opened away from each other. Thus, the noise control module can be prepared and installed on the main wall very easily and rapidly at site. Also since the horizontal length of the first and second additional screens is smaller than the span between the support columns, the closed noise control module can be installed on the top of the main wall by inserting the side frame members into the U-shaped recesses of the support column 41. After securing the side frame members to the support columns, the additional screens can be opened for use. If the gaps between the neighboring additional screens are different in size from one another after the noise control module is installed as in the above, the gap difference can be accommodated by the horizontal elasticity of the sound insulation joint sheets bridged over the support column between the neighboring additional screens. Namely, since the additional screens of the noise control module can be opened and closed, the noise control module can be folded for storage and transport, which will contribute greatly to a space saving and therefore reduced costs of storage and transport. Also, since the first or second additional screen is installed at the lower end thereof to the lower frame member of the noise control module with a clearance defined between them, it is possible to prevent dust or rain from staying inside the space between the additional screens. The first and second further additional screens provided on the additional screens further improve the effect of noise attenuation of the noise barrier.

Claims: A noise barrier including upright-standing support columns (41) spaced a predetermined distance from each other and each made of an H section, and a plurality of wall panels (42) provided between two neighbouring ones of the support columns by inserting each wall panel at opposite lateral edges thereof from above into U-shaped recesses (41A), opposite to each other, of the support columns, the plurality of wall panels being thus stacked one on another to form a main soundproof wall (43), and a noise control module (50) to be installed on the topmost wall panel, the noise control module (50) comprising: side frame members (51) to be inserted at lower$ ends thereof from above into the upper portions of the U-shaped recesses (41A), opposite to each other, of the support columns (41); a lower frame member (52) connecting the side frame members (51) to each other by securing them at lower ends thereof to the lower frame member; first and second additional screens (50A,50B) installed at lower ends thereof pivotably to the lower frame member (52) and having a horizontal length smaller than the distance between the support columns (41); a coupling member (55) holding the first and second additional screens (50A,50B) at a predetermined angle of inclination when the additional screens are inclined toward and away from a noise source, respectively; and elastic sound insulation joint sheets (44) bridging, over the support column (41), said two additional screens (50A,50B) put in neighbouring relationship when they are opened away from each other; and characterized in that the coupling member (55) includes at least two arms (55A,55B) each installed at one end thereof pivotably to upper portions of the first and second additional screens (50A,50B), respectively, and at the other end thereof pivotably and vertically slidably to at least one of the side frame members (51). A noise barrier as claimed in claim 1, characterized in that the first or second additional screen (50A,50B) is installed to the lower frame member (52) with a clearance ( d ) between them to be pivotable in relation to the lower frame member. A noise barrier as claimed in claim 1 or 2, characterized in that the first and second additional screens (50A,50B) have provided as rising from the inner surfaces thereof, respectively, first and second further additional screens (50C,50D) defining open spaces between them and upper portions of their corresponding additional screens. A noise barrier as claimed in claim 3, characterized in that each of the first and second further additional screens (50C,50D) is installed at one end thereof pivotably to inner surfaces of the first and second additional screens (50A,50B), and at the other end thereof to the arms (55A,55B) of the coupling member (55) to be pivotable and slidable longitudinally of the arms.

Inventors: MATSUMOTO KOICH, NAKAZAWA TERUO, OSAFUNE TOSHIKAZU, SHIMA HIROSHI, WATANABE TOSHIYUKI, YAMAMOTO MINORU, MATSUMOTO, KOICH, NAKAZAWA, TERUO, OSAFUNE, TOSHIKAZU, SHIMA, HIROSHI, WATANABE, TOSHIYUKI, YAMAMOTO, MINORU
Applicants: BRIDGESTONE CORP, NIHON DORO KODAN, BRIDGESTONE CORPORATION
Application year: 1998
Main classification: E01F8
IPC codes: E01F8