This invention is related to noise barriers, and more particularly temporary noise barrier structures.
Outdoor noise barriers have been erected next to construction sites for reducing construction noise from reaching nearby residential premises. Virtually all noise barriers have a large surface area for blocking or absorbing sound. In the outdoors, the wind load on such noise barrier structures can be very high occasionally, such as when there is a strong gust of wind. To prevent the noise barriers from being blown down, outdoor noise barriers are necessarily strong and heavy structures, constructed to withstand a wind load of 1 to 1.4 kPa in general. A strong concrete foundation is usually required for tall noise barriers of 6 m to 10 m. The erection and mobilization of such heavy noise barriers are energy and labour intensive, and have to be done using cranes and elevated platforms. Dismantling these heavy structures is also energy and labour intensive. Therefore, when a noise barrier is erected, it is typically intended to be a strong structure to remain standing next to the construction site for a significant period of time.
There is a growing demand for construction noise control in urban areas due to increasing public awareness on noise nuisance. However, if the source of noise lasts for only a short period of time or moves every few hours or days, which is typical of construction work on underground utilities beneath road surface, it would not be practical to erect and move such noise barriers along with the source of noise. Moreover, there may be difficulty in obtaining permission to lay a concrete foundation in some places. Construction of a concrete foundation may also not be allowed at day time due to road congestion, and may be allowable only at night time within a few limited hours. Therefore, it is desirable to provide a noise barrier which is relatively easy to erect, mobilize and dismantle, and which may be used as a temporal structure for a short period of time and which may be able to avoid damaging the existing ground to erect the noise barrier.
In a first aspect, the invention proposes a noise barrier comprising at least one noise barrier panel which is capable of being moved by the force of wind to allow passage of wind.
The invention provides the possibility of reducing wind load on the barrier structure during occasional strong gust, where such strong gust only occurs of once in a few months.
Therefore, the large surface area for blocking noise is capable of being reduced to allow wind to pass through the noise barrier. This effectively limits the wind load to be lower than that of a conventional noise barrier of the same surface area. As a result, the noise barrier does not have to be made of heavy material. The noise barrier can be made of light material. Constructing and dismantling a lightweight noise barrier can be easy, quick and suitable for temporary deployment. Use of cranes, elevated platforms, and concrete foundation is relieved. Noise barrier erection and mobilization can be even done quietly at night.
Typically, the at least one noise barrier panel has a close position for providing barrier to noise, the at least one noise barrier panel has an open position to allow passage of wind, wherein the at least one noise barrier panel is capable of being moved by the force of wind from the closed position to the open position.
Optionally, the at least one noise barrier panel is capable of folding to move from the closed position to the open position. Alternatively, the at least one noise barrier panel is capable of swiveling to move from the closed position to the open position. Any other type of panel configured to make way for wind to pass may be use.
Preferably, the at least one noise barrier panel comprises magnetic material for keeping the at least one noise barrier panel in the closed position. Using magnets improve the precision of positioning the noise barrier panel in the closed position.
More specifically, the at least one noise barrier panel has a first side having a first magnetic material; the at least one noise barrier panel has a second side having a second magnetic material; the second magnetic material of the second side of the at least one noise barrier panel being capable of magnetically cooperating with the first magnetic material of the first side of an adjacent noise barrier panel.
Preferably, the at least one noise barrier panel comprises an inflatable cushion. More preferably, the inflatable cushion contains plurality of inflatable segments. Segmenting the cushion prevents a bulge forming at the centre of the cushion. The gas pressure inside a plurality of inflatable segments provides an upright rigidity to the cushion, allowing the cushion to be held at one side while remaining upright to serve as a noise insulation panel.
Optionally, the inflatable cushion contains a liquid capable of absorbing sound energy. This can improve the sound energy absorption capability of the noise barrier panel.
In a second aspect, the invention proposes a noise barrier comprising at least one mounting pole, at least one noise barrier panel mounted on the at least one mounting pole to be slide-able along the mounting pole. This provides an advantage that a first noise barrier panel can be inserted at the bottom of a mounting pole, and then pushed up by a second noise barrier panel following the first noise barrier panel. An entire pole can be installed with a column of noise barrier panels manually, by a human operator pushing them upwardly from the ground. Even if a machine is required for a heavier embodiment, only a jack is needed to push the noise barrier panel from ground up. This relieves the need of any cranes or heavy machinery for installing noise barrier panels on scaffolding to provide a noise barrier.
In a third aspect, the invention proposes a noise barrier kit, comprising at least one mounting pole, at least one noise barrier panel suitable for mounting on the at least one mounting pole to be slide-able on the mounting pole. Therefore, the user is able to construct his own noise barrier at a time which is convenient to him.
In a forth aspect, the noise barrier panel comprises an inflatable body suitable for mounting onto a mounting pole. Accordingly, the inflatable body can be supplied by any third party manufacturer as long as the dimensions comply with requirements for the mounting.
Preferably, the at least one noise barrier panel comprises a first side having a first magnetic material, a second side having a second magnetic material, the second magnetic material of the second side of the at least one noise barrier panel being capable of magnetically cooperating with the first magnetic material of the first side of an adjacent noise barrier panel.
In a fifth aspect, the invention proposes a method of installing a noise barrier comprising the steps of: providing at least one mounting pole, providing a first noise barrier panel, mounting the first noise barrier panel onto the at least one mounting pole, sliding the first noise barrier panel along the at least one mounting pole. This allows the noise barrier to be constructed simply by pushing the noise barrier panel up from the ground, and relieves the need for cranes to lift noise panels into the air for mid-air installation. Accordingly, the noise barrier can now be constructed with less reliance on heavy machinery.
It will be convenient to further describe the present invention with respect to the accompanying drawings that illustrate possible arrangements of the invention, in which like integers refer to like parts. Other embodiments of the invention are possible, and consequently the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention.
The term ‘wind load’ refers to the pressure or force induced on a structure by wind, and is one of the most critical parameters in outdoor noise barrier design. Wind load is approximately directly proportional to the cross-sectional area of a surface orthogonal to wind direction and square of the wind speed:
F=1/2ρV2ACd (1)
Where:
ρ=Density of air V=Wind speed
A=Cross sectional area orthogonal to wind speed
Cd=Coefficient of drag F=Force of wind load
In some embodiments, the reduction of orthogonal surface area possibly reduces the wind load to one tenth or lower than that of an un-openable noise barrier. It should be noted that Cd is also reduced at the barrier opened position.
Having a low wind load design allows the noise barrier 100 to be made of light weight material. As a result, the noise barrier can be constructed without need of heavy machinery and concrete foundation, and can be erected quickly even as a temporary structure that can be dismantled easily. Accordingly, the noise barrier 100 is capable of quick and temporary deployment near residential estates where installing conventional noise barrier with strong structure is not feasible or cost-effective.
The embodiment comprises two basic parts, namely mounting poles 102 and noise barrier panels 101. Two mounting poles 102 together form a frame 103 across which a noise barrier panel 101 may be placed to absorb or block noise,
The noise barrier panel 101 is a lightweight planar block having a surface for sound blocking and/or absorption. The block arrows show schematically that each noise barrier panel 101 can be mounted onto a mounting pole 102. Each noise barrier panel 101 has a sleeve 105 at one of its lateral sides, for slipping over and being moved along the mounting pole 102. The sleeve 105 is preferably made of a strong fabric or plastic, such as those used for parachutes or for military tents.
The mounting poles 102 are preferably made of a strong and light material such as carbon fiber or aluminium.
Each mounting pole 102 is installed on a base 800. The base 800 can be seen in greater detail in
The lowest noise barrier panel 101 on each mounting pole 102 is supported by a sleeve-ring. An illustration of the sleeve-ring 600 is shown in
Optionally, if higher noise insulation performance is required, the gap 501 between the lowest noise barrier panels 101 of the noise barrier 100 and the ground is closed by flexible noise barrier mats or individual solid panels. The gap 501 is indicated in
The minimum wind strength which can open a noise barrier panel 101 is a threshold determined by the strength of the magnetic and/or mechanical cooperation between two adjacent noise barrier panels 101. The threshold is preferably 0.02 to 0.3 kPa, which corresponding to wind speeds of approximately 20 to 75 kph directly heading on the noise barrier panel 101. This is approximately only 2% to 20% of the wind load required of conventional outdoor noise barriers. When wind speed is below this threshold, the noise barrier panels can remain closed. When wind speed is above this threshold, one or more of the noise barrier panels can be blown open, immediately reducing the wind load on the noise barrier 100 as an automatic mechanism. In this way, the threshold limits the wind load on the noise barrier 100.
Typically, the noise barrier panel 101 is small and lightweight. The surface of each noise barrier panel 101 for facing the construction site is typically less than 5 m2 to keep the noise barrier panel 101 small and manually manageable. The surface density of noise barrier panel 101 is preferably less than 3 kg/m2, in order to keep the noise barrier panel 101 lightweight. In some other cases, the preferred surface density is around 1 to 2 kg/m2.
The framed gas inflatable cushion 901 is wrapped in fabric or plastic sheets, or preferably enveloped in a flexible fabric bag (not illustrated).
The fabric material enveloping the noise barrier panel 101 provides additional sound insulation layers and allows the noise barrier panel 101 to swivel about the sleeve.
Preferably, between the sleeve 105 and the gas inflatable cushion 901 is a smaller sleeve 1105 into which is inserted an aluminium rod. The aluminium rod ensures a minimum distance between the gas inflatable cushion 901 and the sleeve 105 which gives room to swivel the gas inflatable cushion 901. The aluminium rod also provides structure for bearing up the aluminium rod of the panel 101 on top. Correspondingly, the sleeve-ring 600 of
The U-shaped aluminium trough 1101 is configured such that the ends of the U-shaped aluminium troughs 1101 of a column of noise barrier panels 101 can fit into each other (not illustrated). Similarly, the ends of the aluminium tubes in the columns of noise barrier panels 101 can fit one into another (also not illustrated).
As the skilled man will know, variations of the locking mechanism are possible. For example, the magnets are attached to the free-swinging vertical side 107 of the noise barrier panel 101 and a ferromagnetic material such as galvanized steel is placed in the U-shaped aluminium trough 1101. Alternatively, magnets are attached both to in the U-shaped aluminium trough 1101 and at the free-swinging vertical side 107.
Typically, the strengths of the locking mechanisms and the magnetic cooperation between all the noise barrier panels 101 are the same. Every noise barrier panel 101 has the same wind load threshold.
In a variation of the embodiment, different noise barrier panels 101 are provided with different strengths of locking mechanism and magnetic cooperation with the sleeve 105 of the adjacent noise barrier panel 101; different noise barrier panels 101 are tuned to different wind load thresholds. The noise barrier panels 101 at the top of the mounting poles 102 can have the lowest threshold in order to limit the wind load at the upper end of the mounting poles 102, and the threshold of the noise barrier panels 101 lower on the mounting poles 102 is greater.
In the simplest mode, a noise barrier panel 101 in the open position can be closed using a rod to push the noise barrier panel 101 back towards the closed position, and the magnetic attraction between the free-swinging vertical side 107 of a noise barrier panel 101 and the sleeve 105 of the adjacent noise barrier panel 101 will attract the noise barrier panel 101 back into the closed position. Optionally, a resilient device such as a weak spring can be used to urge each noise barrier panel 101 into the closed position. The spring has to be weak enough not to interfere with the threshold level of wind load at which the noise barrier panel 101 should open. Alternatively, as shown schematically in
In a variation of the embodiment, the noise barrier panels 101 on the same mounting pole 102 can be locked together, so that the column of noise barrier panels 101 behaves like one large panel. Thus, to dose the column of noise barrier panels 101, the operator need only push the lowest noise barrier panel 101 back into the dosed position.
The described noise barrier 100 possibly provide sound insulation performance similar to a conventional noise barrier, at up to Noise Isolation Class 30 and providing more than 35 dB(A) reduction of white noise.
The frame 103 is provided with a rail system 2000 for installation of noise barrier panels 101. The rail system 2000 is pivoted to the top of each mounting pole 102. Each rail 2000 is almost as long as the mounting pole 102. The black block arrow in
Between the ends of the mounting tube of a higher panel 101a and the corresponding ends of a mounting tube of a lower panel 101b are inserted dividers such as rods (not shown), i.e. between points A to A and between points B to B as labeled in
To provide an effective noise barrier wall, the bottom edge of a top noise barrier panel 101 preferably overlaps, or is aligned closely to the top edge of a bottom noise barrier panel 101.
When the wind load is high above the threshold, gaps between the overlapping panel edges are provided automatically by a shape-changing mechanism of the panels 101 to reduce the wind load. The shape-changing mechanism is provided by the material used for the body of the noise barrier panel 101. The material can be any which is flexible and bend-able to allow wind passage, and resilient enough to revert to the original position under normal wind condition. It is preferred that the body of the noise barrier panel 101 comprises a cushion 901 made of segmented gas inflated tubes 903, such as the one discussed in
Since wind load on the noise barrier 100 is limited by a shape-changing mechanism, noise barrier 100 does not need to be made of heavy material or a concrete foundation, and can be made of light material which is easy for manual installation.
When the wind dies down, the resilience in the noise barrier panel 101 material returns the noise barrier panel 101 into its original configuration automatically, to resume function as noise barrier.
Therefore, wind load on the noise barrier 100 is limited by the wind load threshold at which the noise barrier panels 101 open. It is estimated that the wind load on the fully open noise barrier is only one-tenth of the barrier without opening, at between 0.02 to 0.3 kPa, which is only 2% to 25% of the conventional outdoor noise barrier loading requirement of about 1.2 kPa. This makes it possible to construct the embodiment with light material. The light material provides that the noise barrier is so easy to erect and dismantle, without using cranes or elevated platforms, that it is suitable for temporal, short period use.
The noise barrier panels of this embodiment is small and lightweight with a preferable size of less than 5 m2 and surface density less than 2 kg/m2.
In a variation of the embodiment, the edges of a noise barrier panel 101 are provided with magnetic material to act as magnetic locks. The magnetic material in the lateral edges of the noise barrier panel 101 is attracted to corresponding magnetic material in the vertical mounting poles 102. In this case, determining the threshold wind load has to take into account the strength of the magnetic attraction between the free edges of the noise barrier panel 101 and the mounting poles 102.
The described noise barrier panels 101 do not require a pivoting mechanism to flap open in the wind, as they are capable of deforming in wind. However, if the noise barrier panel 101 is made of a rigid and unbendable material, the noise barrier panel 101 is secured to the frame by a pivoting mechanism. For example, the mounting tubes 1905 can be mounted on the railing to be able to turn pivotally.
Where the embodiments of
In practice, three grades of noise barriers can be provided depending on site condition:
Grade 1 noise barrier has a lightweight structure which is designed for daily installation and removal. Flexible noise barrier panels are designed to be detached from the frame structure under extreme wind to minimize wind load. The maximum loading of the structure is designed to be in the range of 5 to 20 kg/m2 of the noise barrier.
Grade 2 noise barrier has a slightly stronger structure than Grade 1 which is designed for temporary use for several months. Daily installation and removal is not required but removal before typhoon may be necessary. The maximum loading of the structure is designed to be in the range of 10 to 50 kg/m2 of the noise barrier.
Grade 3 noise barrier is designed as a permanent structure which can withstand the worst wind load condition with sufficient safety factor. It has the strongest structure among the three types of noise barrier but the structure requirement is still less than the conventional barrier of the same height, due to wind load reducing mechanisms as described. The maximum loading of the structure is designed to be in the range of 50 to 100 kg/m2 of the noise barrier.
Accordingly, a noise barrier 100 has been described comprising at least one noise barrier panel 101 which is capable of being moved by the force of wind to allow passage of wind.
In a preferred embodiment, the noise barrier 100 comprises at least one noise barrier panel 101, the at least one noise barrier panel 101 having a dose position for providing barrier to noise, the at least one noise barrier panel 101 having an open position to allow passage of wind, wherein the at least one noise barrier panel 101 is capable of being moved by the force of wind from the closed to the open position. Embodiments have been described wherein the noise barrier panel 101 opens by turning or folding relative to a vertical axis or a horizontal axis.
A noise barrier 100 has also been described comprising at least one mounting pole, 102 at least one noise barrier panel 101 mounted on the at least one mounting pole 102 to be slide-able on the mounting pole 102.
The noise barrier 100 can be set up by an operating company, or if the user prefers, the user can order a noise barrier kit, comprising at least one mounting pole, at least one noise barrier panel suitable for mounting onto the at least one mounting pole to be slide-able along the mounting pole. The user can set up the noise barrier himself at any time convenient for him without requiring any heavy machinery.
While there has been described in the foregoing description preferred embodiments of the present invention, it will be understood by those skilled in the technology concerned that many variations or modifications in details of design, construction or operation may be made without departing from the scope of the present invention as claimed.
For example, even though a X-shape cross bar is described in
For example, the mounting pole 102 is foldable or retractable.
This application is a National Stage of PCT International application no. PCT/CN2014/075173, filed 11 Apr. 2014, claiming priority in U.S. Provisional patent application No. 61/811,137 filed 12 Apr. 2013 and no. 61/931,693 filed 27 Jan. 2014, the contents of these documents being incorporated herein by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/CN2014/075173 | 4/11/2014 | WO | 00 |
Number | Date | Country | |
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61931693 | Jan 2014 | US | |
61811137 | Apr 2013 | US |