Do highway sound barriers work?
When planning a city, you should always consider a few steps ahead. Because our world is developing, the human population is increasing and the migration to the city is constantly increasing due to economic conditions. New living spaces need to be established for the increasing human population. These living spaces should be located so that people can live a comfortable life. If this is not the case, there should be a way to protect people from noise. This is where highway noise barriers come into our lives. Today, the most widely used soundproof fencing traffic noise block the sound and prevent it from spreading to the environment.
When the voices around us start to disturb us, we perceive it as noise. Noise is not only disturbing but also negatively affects our physical and mental health. For this, legal regulations have been made to control the noise. Turkey on Environmental Noise Assessment in force since 2005 and the Management Regulations of the exposure to environmental noise result of people’s peace and tranquility of the aims of taking the necessary measures to preserve the physical and mental health.
In parallel with the increase in the population, with the increasing traffic and expectations about the quality of life. Noise becomes an important issue in the development and operation of road and railway networks. Therefore, road noise reduction fence; noise barriers, which are an effective solution for controlling traffic-induced noise, appear as a necessary and visual component of the road and rail network.
Since the first noise barrier was built in California in 1968, noise control barriers have been the subject of much research around the world. From an acoustic perspective, these studies show that noise barriers are an effective method of protection from noise. However, when the urban design and aesthetic aspects are examined, the results may vary. The general opinion about sound barriers is that they are visually monotonous and dominant structures. For this reason, it is tried to obtain designs that will not cause a visual disturbance with various design and material alternatives. In short, noise barriers are not only about acoustics but are also a subject of a city landscape.
Working Principle of Noise Barriers
In order to express the movement of sound waves on the noise barrier in a simple language, we can think of sound waves as a series of rays emitted from the source. The sound from the source will reach the receiver directly in a straight line or indirectly by reflection or diffraction. By placing a highway sound barrier between the source and the receiver, the direct path from the source to the receiver is prevented. The movements of the sound waves on a noise barrier wall are shown schematically below.
When assessing the noise reduction effect of environmental noise barriers, the distance, height, and design of the barrier to the source and receiver should be considered. When making this assessment, first the noise-canceling barrier should be placed between the source and the receiver. In principle, the closer a highway sound barrier is to the source, the higher its effect in reducing sound. How close the barrier can be positioned to the source is determined by the project-specific and constraints in the project.
Another criterion for highway sound barriers is the barrier height. For the barrier to be effective, it must be high enough. Therefore, in order to be reasonable and feasible for the construction of a noise barrier at the edge of a transportation line, the heights of the buildings and the structures affected by the noise should be examined. Since the acoustic barrier fence height can create problems in terms of aesthetics and cost in practice. The height issue should be handled on a project-specific basis before the construction of the barriers. Especially when determining the height of the barriers to be built on the edge of urban transport networks, the height criterion required to ensure adequate noise reduction may not apply, and the visual impact of the barrier height may be decisive for the final decision.
What are the Materials of Noise Barriers
Today, noise barriers can be made of various materials. These materials include concrete, metal, plastic, transparent materials (such as acrylic and glass), clay masonry units, wood, and reinforced gas concrete and rubber sound barrier panels. In addition to this, planting, planting soil sets or noise barriers built on the sets are also used for noise control.
When selecting materials, the criteria related to the visual character and structural quality of the material in the landscape should be considered together. Structural durability, weather resistance, need for maintenance and repair, fire resistance, ease of installation, initial and life cycle cost are among the criteria that should be considered besides acoustic requirements. In addition, vandalism resistant materials should be preferred. Soft and light materials that can be cut and scratched can easily be damaged.
The criteria that are effective in noise barrier design can be divided into two categories as acoustic and non-acoustic criteria. The issue of ‘aesthetics alan, which is among the non-acoustic criteria, is very important. Since noise barriers are tall and tall buildings due to their structure, they should be designed with a holistic approach by considering the urban architecture, landscaping, the visual effects on neighboring buildings, and the visual effects on the road together with its acoustic and structural performance.
The visual perception of noise barriers should be considered in two different ways: While they are perceived by drivers as a linear and temporary structure. They are perceived as a part of the permanent structure and landscape they see every day by the occupants and pedestrians in the adjacent buildings.
In some approaches, highway soundproof walls are placed as a monumental element in the existing landscape, materials and details are selected accordingly. In another approach, it is included in the landscape in a way that is unobtrusive and compatible with the environment. No matter which design approach is adopted, highway noise barriers should be designed considering the architecture and landscape of the environment in which they are located. Hatko Noise Barrier provides alternative solutions that enable various barrier designs with its acoustic and structural features.
Acoustic Performance of Noise Barrier
- Sound insulation:
Noise barriers with sufficient sound insulation value significantly prevent the direct transmission of sound waves. The sound insulation of a noise barrier depends on the mass of the material. Therefore, the mass of the materials to be used in the noise barrier should not be less than 20 kg / m2. The mass of the 15 cm thick Hatko Noise Barrier (class G3), which has been acoustically tested, is 108 kg / m2.
The performance of a noise barrier for airborne sound insulation is expressed as an odd number in dB by DLR. The DLR of Hatko noise barriers is 39 dB for road traffic noise and 41 dB for railway traffic noise. The system is certified for both noise sources. According to Annex A of TS EN 1793-2, the noise reduction class of Hatko Noise Barrier panels is found to be B4. B4 represents the best performance class in the classification of airborne sound insulation.
Even if we use material of sufficient density for sound insulation, sealing between the component materials must be ensured. Even a small gap/hole will significantly reduce the performance of the barrier. When mentioning the structural life of a noise barrier, the formation of such small holes and voids in the material should also be taken into account. Hatko Sound Barriers during the life of any section loss, holes, gap formation is not observed.
- Diffraction of sound:
The sound broken from the peak of the noise barrier is one of the factors affecting the acoustic performance of the barrier. If the receiver is in the acoustic shadow zone of the barrier as significant reductions in overall sound level on the receiver side can be achieved. In the effect of the broken sound on the overall sound level, the length of the sound traveled is also important. By building higher barriers, the sound path can be extended, but this will not always be a viable solution. In this case, designs can be made to change the angle of diffraction at the peak of the barrier. The Hatko Noise Barrier can be designed to allow such designs.
- Reflection / absorption of sound:
When a barrier is made between the noise source and the receiver, the sound from the source reaches the receiver indirectly by diffraction and reflection. The reflected sound can act as a noise source, especially on hard and smooth surfaces, and increase the overall sound level on the receiver side. It is possible to reduce the effect of the reflected sound by a number of measures. For this purpose, sound-absorbing coatings can be applied to the surface of the barrier facing the source of noise, or by changing the geometry of the barrier, the reflection angle of the sound can be directed such that it does not reach the receiver.
At this point, the materials on which the barrier will be constructed and the design principles should be considered together. For example, curved barriers may be preferred over vertical barriers. Considering that Hatko sound panels are placed between steel poles, inclined barriers can easily be obtained by placing the poles obliquely.
Non-Acoustic Performance of Noise Barriers
- Maintenance / Repair:
Noise barriers need maintenance or repair over time after construction. This is one of the issues to be considered during the design phase. For example, when there is a need for maintenance, maintenance personnel should be able to reach both sides of the barrier easily and safely and maintenance and repair operations should be carried out without disrupting traffic without closing the lane. When selecting materials, care costs should be kept to a minimum. This should be borne in mind when making a cost-effectiveness comparison of various materials. Hatko Noise Barriers do not corrode over time, are stainless, do not deform and corrode. Thanks to the simple application technique, the replacement of a damaged panel can be easily removed without damaging the other panels. Because maintenance costs are low, it provides economy in terms of life cycle costs.
Roadside noise barriers are subjected to various loads due to wind load, pressure, and traction caused by vehicles passing by, or their own weight. The impact of the stones thrown by the vehicles and the snow weight. Due to the collected snow are the loads expected to affect the barriers. Hatko Noise Barrier panels are produced by placing steel reinforcements that are determined as a result of a static calculation. In such a way that they are resistant to these loads that are expected to affect them.
- Weather resistance:
Noise barriers must be in continuous form and weather resistant. It must be permanently resistant and free from cracks, holes, open joints. Hatko panels are durable construction elements that are resistant to weather conditions and can be used in all climate zones in Turkey. They join each other with the lamp-tenon profile structure in panel joining regions. Thus, the panel joints are sealed against sound and water effects. To protect the surface of Hatko panels from freeze-thaw effects, it is recommended to apply a surface protective primer.
- Installation speed:
Traffic noise disruptions may occur during the construction of noise barriers. The road may need to be completely closed to traffic. Therefore, the construction phase should be completed as soon as possible and installation should be done with as little equipment as possible. The installation speed of Hatko noise panels is high. The panels are shipped from the factory as finished products, and only the panels are placed in place.
It may be exposed to noise barriers, forest fires, droughts, ignition of nearby flammable materials, or traffic accidents. Therefore fire-resistant materials should be preferred. In addition, in case of fire, it is requested not to release toxic gases. It is preferable to use substantially recyclable materials. Sound panels are A1 class ‘not flammable’ and long term fire-resistant construction material. Do not release toxic gases during a fire.
Noise Barriers can be applied directly to the paint. The surface can be processed and allows various visual designs on it. With various designs and coloring, a visual effect can be obtained that will not disturb. The inhabitants and can be incorporated into the city architecture to adapt to the environment in which it is applied. By placing solar panels on the barriers, positive effects can also be achieved in other energy and environment-related areas.
- Environment friendly:
The noise barrier is produced from natural raw materials that do not harm the environment. No toxic or environmental pollutants are generated during the life cycle.
Noise has many negative effects on human health and the comfort of life. Depending on the level of exposure to noise, we may experience various health problems, including hearing loss. Therefore, various legal arrangements are made in order to take the necessary measures to live in a healthy environment. For example; In the Regulation on Assessment and Management of Environmental Noise, limit values are set for traffic noise levels, which is one of the most exposed noise sources.
Highway sound barriers are a very effective method of controlling environmental noise caused by traffic. It is a widely preferred method as a noise protection measure all over the world. Turkey has also carried out studies on this issue are encouraged to make arrangements with a variety of noise barriers.
Noise barriers are visually dominant structures due to their structure and they have a high impact on the surrounding landscape. For this reason, when designing the barrier, the acoustic and structural performance of the barrier. And its impact on city architecture. And landscape should be considered as a whole, how it is perceived by the inhabitants of neighboring buildings. Here, the material used in the construction of the barrier and the geometry of the barrier is important.
Highway sound barriers provide aesthetic and effective solutions for preventing traffic noise. Due to their economical, superior physical properties, ease of application, robustness, various surface applications. And the possibility of obtaining various forms in barrier geometry.
You can always contact Hatko Sound Barriers for more detailed information.
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