GB2258482A

GB2258482A - Noise barrier

Info

Publication number: GB2258482A
Application number: GB9116615A
Authority: GB
Inventors: Brian George Margetson
Original assignee: PRIME CONSTRUCTION CONCEPTS LI
Current assignee: PRIME CONSTRUCTION CONCEPTS LI
Priority date: 1991-08-01
Filing date: 1991-08-01
Publication date: 1993-02-10
Also published as: GB9116615D0

Abstract

A sound absorbing panel has a sound absorbing mat (12) located towards the front thereof and a sound reflecting back wall (11). The sound absorbing mat (12) is made water-repellant by impregnating the surface thereof with a silicone binder. The integrity of the front surface of the mater (12) can be ensured by affixing a plastics non-woven tissue thereover by means of a hot melt adhesive. The panels are used to form a noise barrier by stacking them edge-to-edge between pairs of stanchions. <IMAGE>

Description

NOISE BARRIER DESCRIPTION The present invention relates to noise barriers and sound absorbing panels therefor.

In recent years, environmental considerations have become successively more important when decisions are made regarding major building works. In particular, residents have increasingly voiced their concerns regarding noise levels. Since roads and railways, by their nature, must pass through built-up areas, there is a need to solve the problem of noise pollution in order for a new road or railway line to be acceptable to the public.

The linear nature of roads and railway lines means that noise reducing structures must be installed over distances of several miles. It is, therefore, important that noise reducing structures be not only effective but also cheap to install.

It is an aim of the present invention to enable effective and economic noise control for roads and railway lines. However, it is not intended to restrict the utility of the present invention to roads and railways.

According to a first aspect of the present invention, there is provided a sound absorbing panel comprising a sound absorbant mat and a sound reflecting member, arranged such that sound not absorbed by the mat during a first pass is reflected back to the mat.

Advantageously, the sound reflecting member comprises a sheet of laminated material, e.g. plywood.

Preferably, the panel includes a sound-receiving wall which may comprise a plurality of slats. Alternatively, it may comprise a sheet of plywood which could be apertured.

Preferably, the sound absorbing mat is formed from a mineral fibre fabric. The mat can be made waterrepellant by the use of a silicone binder. The integrity of a surface of the mat can be ensured by affixing a plastics non-woven tissue thereover by means of a hot melt adhesive.

In one preferred embodiment, the panel comprises two parallel spaced sound-receiving walls with a sound reflecting member located therebetween and arranged to reflect sound propagating from both sound-receiving walls.

According to a second aspect of the present invention, there is provided a noise barrier comprising a plurality of spaced stanchions between which a panel, according to the first aspect of the present invention, is supported with its sound-receiving wall directed towards a source of noise.

Advantageously, a plurality of panels may be stacked edge to edge between the stanchions.

Preferably, the stanchions are shaped to receive the edge portions of the panels for assembly.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a front view of a first embodiment of a panel according to the present invention; Figure 2 is a sectional view of the panel in Figure 1 at the line A-A; Figure 3 is a front view of the frame of the panel in Figure 1; Figure 4 is a sectional view of a second embodiment of a panel according to the present invention; Figure 5 is a sectional view of a third embodiment of a panel according to the present invention; Figure 6 is a front view of a noise barrier according to the present invention; Figure 7 is a rear view of the noise barrier shown in Figure 6; and Figure 8 is a sectional view of the noise barrier in Figure 6 at the line B-B.

Referring to Figures 1, 2 and 3, a sound absorbing panel 1 has a rectangular, softwood frame including a top rail 2, a bottom rail 3 and two end rails 4, 5. A bracing member 6 extends between the top and bottom rails 2, 3, at a point mid-way between the end rails 4,5, to enhance the rigidity of the structure. The frame elements are all of the same cross-section, with the exception of the top rail 2 which is deeper, and are arranged such that their frontmost faces all lie in a common plane. Therefore, when the frame is constructed the top rail 2 extends back beyond the plane common to the rear faces of the other frame elements.

A series of stop rails 7, 8, 9, 10 are affixed to the inwardly directed faces of the top and bottom rails 2, 3 and extend between respective end rails 4, 5 and the bracing member 6. The stop rails 7, 8, 9, 10 are positioned so that their rearmost faces lie in the plane of the rear face of the bottom rail 3 and are dimensioned so as to extend forwards for between approximately one third and two thirds of the depth of the frame.

The rear wall 11 of the panel 1 is formed by a sheet of plywood. The plywood is dimensioned to extend across the full width of the frame and from the bottom of the frame to the bottom face 2a of the top rail 2 which it abuts.

A sound absorbing mat 12, of a water-repellant mineral fibre fabric, lies within the frame in a plane parallel to the rear wall 11 on either side of the bracing member 6. The mats 12 are arranged such that the front faces of the stop rails 7, 8, 9, 10 are each overlain by mat margins. The mineral fibre fabric is made water-repellant by impregnating a surface thereof with a silicone binder.

The mats 12 are held in position by four slats 13a-d which extend horizontally across the front of the panel 1. The lowest slat 13d is arranged to project below the bottom rail 3.

In order to prevent the loss of small quantities of mat material, for example by the actions of nesting birds, a plastics non-woven tissue is affixed across the surfaces of the mats, to be exposed, by means of a hot melt adhesive. Alternatively or additionally, a sheet of a glass fibre fabric or a fine wire mesh can be located between the mats 12 and the slats 13a-d.

Chambers 27 are defined within the panel 1 by the mats 12, the rear wall 11 and the frame.

In another embodiment, shown in Figure 4, the bottom rail 3 projects from the front of the panel 1 and the slats 13a-d are replaced by a second sheet of plywood 14. The second sheet of plywood 14 is fixed in a similar manner to the sheet used for the rear wall 11 but extends from the top of the panel 1 to the top face 3a of the bottom rail 3 which it abuts.

A further embodiment, which is arranged to absorb sound propagating from opposite directions, is shown in Figure 5. A rectangular frame is formed from five rails, including a top rail 15 and a bottom rail 16, two end rails and a bracing member, in a similar manner to that described above. The depth of the frame is approximately twice that of the enmbodiments described above. Two sheets of plywood 17 are located mid-way between the major faces of the panel; one on either side of the bracing member. The plywood sheets 17 are dimensioned to fill the apertures defined by the frame.

Stop rails 18 are affixed to the frame on either side of the top and bottom margins of the plywood sheets 17.

Mats 19 of sound absorbing material lie across the major faces of the panel, separated from the plywood sheets 17 by the stop rails 18. Four horizontal slats 20a-d extend across each major face of the panel. The lowest slats 20d are arranged such that they extend below the bottom rail 16 of the frame.

Figures 6, 7 and 8 show a noise barrier 22 formed from panels 1 of the type shown in Figures 1, 2 and 3. The barrier comprises a plurality of spaced stanchions 23.

Rectangular cross-section ground beams 24, partially sunk into the ground, extend between pairs of stanchions 23. A sound absorbing panel 1 is located with its bottom rail 3 resting on the upper surface of the ground beam 24. The stanchions 23 have an H-shaped cross-section, the spaces between the legs of the H being adapted to receive the vertical margins of the panel 1.

In the embodiment shown, further panels 1 are stacked, bottom rail 3 to top rail 2, above the panel 1 resting on the ground beam 24, until the top rail 2 of the uppermost panel 1 is substantially level with the top of the stanchions 23. A weather rail 25 extends along the top of the noise barrier.

For use the noise barrier 22 is erected by the side of, for instance, a motorway. The noise barrier intercepts sound waves generated by the passing traffic and propagating towards the side of the motorway. Sound waves, incident on a sound absorbing panel 1, pass through the front wall of the panel 1, e.g. formed by the slats 13a-d, and are then attenuated by the mats 12. Any sound energy, not absorbed, passes on through the chamber 27 and is reflected from the forwardly facing surface of the rear wall 11 back through the chamber 27. The reflected sound energy then returns to the mats 12 where it is further attenuated.

A noise barrier employing the panel 1, as shown in Figure 5, would be suitable for use along the central reservation of a motorway. The use of a noise barrier along the central reservation enables sound, which would otherwise propagate over a barrier at the side of the motorway, to be intercepted.

Whilst a noise barrier employing the panel shown in Figures 1, 2 and 3 has been described, any panel according to the first aspect of the present invention could be used in the arrangement shown in Figures 6, 7 and 8.

Although the stanchions 23 are shown vertical, they may also be inclined.

Claims

1. A sound absorbing panel comprising a sound absorbant mat and a sound reflecting member, arranged such that sound not absorbed by the mat during a first pass is reflected back to the mat.

2. A sound absorbing panel according to claim 1, wherein the sound reflecting member comprises a sheet of laminated material.

3. A sound absorbing panel according to claim 2, wherein the reflecting member comprises a sheet of plywood.

4. A sound absorbing panel according to claim 1, 2 or 3, further comprising a sound-receiving wall.

5. A sound absorbing panel according to claim 4, wherein the sound-receiving wall comprises a plurality of slats.

6. A sound absorbing panel according to claim 4, wherein the sound-receiving wall comprises a sheet of laminated material.

7. A sound absorbing panel according to claim 6, wherein the sound receiving wall is apertured.

8. A sound absorbing panel according to claim 6 or 7, wherein the sound-receiving wall comprises a sheet of plywood.

9. A sound absorbing panel according to any preceding claim, comprising two parallel spaced sound-receiving walls with the sound reflecting member located therebetween and arranged to reflect sound propagating from both sound-receiving walls.

10. A sound absorbing panel according to any preceding claim, wherein the sound absorbant mat is formed from mineral fibre fabric , treated to make it water-repellant.

11. A sound absorbing panel according to any preceding claim, wherein the sound absorbent mat is formed from mineral fibre fabric having a plastics non-woven tissue affixed to a surface thereof.

12. A sound absorbing panel substantially as hereinbefore described with reference to Figures 1, 2 and 3.

13. A sound absorbing panel substantially as hereinbefore described with reference to Figure 4.

14. A sound absorbing panel substantially as hereinbefore described with reference to Figure 5.

15. A noise barrier comprising a plurality of spaced stanchions between which a panel, according to any preceding claim, is supported with its sound-receiving wall directed to a source of noise.

16. A noise barrier according to claim 15, comprising a plurality a panels stacked edge to edge between pairs of stanchions.

17. A noise barrier according to claim 15 or 16, wherein the stanchions are shaped to receive edge portions of a panel to thereby support the panel.

18. A noise barrier substantially as hereinbefore described with reference to Figures 6, 7 and 8.