Road Resonators for Lateral Sound Diffraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sound attenuating measures for roads, such as noise-reducing screens and barriers, are expensive, landscape-disruptive, obstruct views, and have limited effectiveness, especially with varying wind directions and increased traffic intensity.
Innovation Solution
A road design incorporating resonators with high porosity that diffract sound waves rather than absorb them, using elongated cavities or Helmholtz resonators buried close to the road, which deflect traffic noise vertically, creating a virtual sound barrier that reduces lateral sound propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If noise-reducing screens or noise barriers are used, then sound attenuation is achieved, but the landscape is adversely affected and views are obstructed
Solution Approach 1:
The invention extracts the sound-attenuating function from visible above-ground structures (noise barriers) and relocates it to subsurface resonators embedded in the road structure. The resonators are positioned below the road surface, making them invisible to passersby while maintaining their acoustic function. This separates the functional element (sound attenuation) from the visual element (landscape appearance).
Solution Approach 2:
The invention transitions the sound-attenuating structure from the vertical dimension (above-ground noise barriers) to the horizontal/subsurface dimension (resonators embedded in the road). By placing resonators within the road structure at a depth of 10-50 cm, the solution utilizes the subsurface space to achieve sound attenuation without occupying visual space above the road level.
2Object-affected harmful factors
If noise-reducing screens are installed, then sound attenuation is provided, but costs increase and installation becomes complex
Solution Approach 1:
The invention merges the sound-attenuating resonators with the existing road structure. The resonators are embedded within the road pavement during road construction or renovation, combining the acoustic function with the structural function of the road. This integration eliminates the need for separate noise barrier installations and reduces overall project complexity.
Solution Approach 2:
The resonators are designed to be self-contained units that can be manufactured as standardized elements and then integrated into the road structure. Each resonator module is a complete, self-sufficient acoustic element that requires minimal additional installation infrastructure, simplifying the overall manufacturing and deployment process.
3Object-affected harmful factors
If traditional sound attenuating measures are used, then some noise reduction is achieved, but effectiveness is limited by wind direction
Solution Approach 1:
The resonators are positioned locally at the source of noise generation (embedded in the road surface directly under or near the traffic lanes). This local placement ensures that the resonators intercept sound waves regardless of their propagation direction caused by wind. The resonators create a localized sound field modification that is effective in all directions, not just downwind.
Solution Approach 2:
The resonators operate by creating controlled vibrations at specific resonant frequencies that counteract the traffic noise. These vibrations are generated within the resonator structure itself and radiate outward in all directions, creating an omnidirectional sound field modification that is independent of wind direction. The mechanical vibration mechanism inherently provides 360-degree coverage.
4Object-affected harmful factors
If resonators with high porosity are used, then sound diffraction is improved, but structural strength may be compromised
Solution Approach 1:
The resonators are constructed using composite materials that combine acoustic functionality with structural strength. The resonator structure incorporates porous or perforated elements for sound diffraction while using reinforcing materials (such as reinforced concrete or metal alloys) to maintain structural integrity. This composite approach allows the coexistence of high porosity for acoustic performance and sufficient strength for load-bearing requirements.
Solution Approach 2:
The resonator design employs a nested structure where the porous acoustic elements are embedded within a stronger outer shell or framework. The inner porous structure provides sound diffraction functionality, while the outer structural layer provides mechanical strength. This nested arrangement allows both requirements to be satisfied simultaneously without compromising either acoustic performance or structural integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution provides significant sound reduction (up to 3-5 dB) in specific frequency bands, particularly in the 700-800 Hz range, without obstructing views or affecting landscapes, and is independent of wind direction, offering a cost-effective and efficient noise mitigation strategy.
Implementation Method 1
the resonators are caused to resonate at the relevant resonance frequency or resonance frequencies. It is assumed here that the sound for treating has substantial frequency components at the resonance frequency or frequencies. The relevant sound is emitted in substantially vertical direction and thus has a barrier effect on the sound propagation in lateral direction.
Implementation Method 2
When orifices of the resonators are exposed to traffic noise, they will begin to display one or more resonances in accordance with their design. As a result the air at the location of the orifice will be caused to resonate at the relevant resonance frequency or resonance frequencies.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a road with at least one traffic lane for motorized vehicular traffic, to which road are added sound attenuating means which limit, at least for determined frequency ranges, the lateral emission of sound caused by traffic travelling over the road, and has the feature that a pattern of resonators placed in distributed manner is arranged at least locally over a chosen length along the traffic lane, which resonators each comprise an acoustically hard, non-absorbing resonance space placed under the surface and debouching in an orifice situated at least roughly at a level of the surface of a roadside edge adjacent to the traffic lane, which resonators have resonance frequencies lying in the range of the frequencies of the sound for attenuating, in particular frequencies around about 1 kHz.