Reducing Road Noise: Practical Steps To Quieter Streets

Noise pollution is a significant environmental and health hazard, with road traffic being a major contributor. The adverse effects of noise pollution include stress, sleep disturbance, cardiovascular issues, and cognitive impairment. In Europe, noise pollution from traffic is responsible for 12,000 premature deaths annually and affects millions of people living near highways and busy roads. To combat this issue, various methods can be employed to reduce noise pollution on roads. These include the use of noise barriers, sound-diffracting walls, low-noise pavement, traffic management strategies, and the promotion of quieter vehicles and road surfaces. Additionally, innovative approaches such as noise-canceling technology and green infrastructure are also being explored to mitigate the impact of road noise on surrounding communities.

Install noise barriers

Installing noise barriers is an effective way to reduce unwanted noise from roads and highways. These barriers can be constructed using a variety of materials, including concrete, wood, plastic, steel, and masonry. However, a unique solution comes in the form of sound-diffracting walls developed by 4Silence BV, a Dutch company. These walls, rather than blocking noise, bend sound waves and direct them away from homes, a phenomenon known as diffraction. This innovative approach offers several advantages over traditional methods.

Firstly, the 4Silence walls are more space-efficient. Due to the way they redirect sound, these barriers can be smaller and shorter than conventional noise barriers while achieving the same level of noise reduction. This not only saves space but also makes them more aesthetically pleasing, creating a united rather than divided community.

Secondly, the 4Silence walls are easier on the budget. They are approximately half the cost of traditional noise-reduction measures, which is beneficial for governments and communities looking for cost-effective solutions. The reduced cost also means that more barriers can be installed for the same budget, providing noise protection to a larger number of people.

Additionally, the 4Silence walls are easy to install and maintain. The company claims that their barriers are simple to set up and do not require extensive maintenance, making them a convenient choice for local governments and municipalities.

It is important to note that while noise barriers are effective, they may not always be the best solution. In some cases, they can even make the noise problem worse, as sound waves can reflect off the barriers and create additional noise issues. This is a complex issue influenced by factors such as wind, humidity, and the presence of hills or freeway openings. Therefore, careful consideration and planning are necessary to ensure that noise barriers are appropriately designed and placed to maximize their effectiveness.

Overall, installing noise barriers is a viable strategy to reduce road noise, and the 4Silence sound-diffracting walls offer a promising alternative to traditional methods. However, each situation is unique, and a combination of solutions, such as noise barriers, quieter road surfaces, and traffic management, may be needed to effectively address noise pollution on roads.

Use low-noise pavement

One of the most effective ways to reduce noise pollution on roads is to use low-noise pavement. This involves utilising specific types of asphalt or concrete that have noise-reducing properties. The application of these materials in road construction can significantly minimise the impact of traffic noise on nearby residents and the environment.

The concept of low-noise pavement revolves around the use of specialised mixtures and textures that dampen the sound of tyre-road interaction. For example, porous asphalt, also known as porous asphalt concrete (PAC), is a common choice for its noise-reducing capabilities. PAC is designed with a high level of porosity, creating a sponge-like surface that absorbs sound waves and reduces the transmission of noise. This type of pavement has been widely adopted in countries like Japan and the Netherlands, contributing to improved acoustic conditions and even a decrease in traffic accidents on wet surfaces.

In addition to porous asphalt, thin-surface, gap-graded asphalt mixes are another popular option for low-noise pavement. These mixes, such as NovaChip, microsurfacing, and stone matrix asphalt (SMA), are often used in urban areas with severe winter weather conditions. The small aggregate size in these mixtures helps to reduce tyre noise. The European trend is to use thin-surfaced, negatively textured mixes, as positively textured pavements like chip seals tend to increase noise levels.

The benefits of low-noise pavement extend beyond just noise reduction. These specialised pavements are also designed to be durable and long-lasting, even in severe climate conditions. For instance, in Lithuania, low-noise asphalt mixtures are engineered to withstand a large number of frost-thaw cycles during the winter. Additionally, low-noise pavement can contribute to improved road safety and driving experiences, as certain mixtures provide better traction and reduce the risk of accidents.

The implementation of low-noise pavement has been a focus of research and development worldwide. Organisations like the Federal Highway Administration (FHWA) in the United States and similar groups in Europe have been actively investigating and refining asphalt and concrete pavement technology to optimise their noise-reducing capabilities. These efforts involve exploring various materials and textures, such as thin asphalt surfaces, porous asphalt, and alternative materials, to identify the most effective combinations for noise reduction.

Implement noise-cancelling technology

Noise-cancelling technology is an innovative way to reduce noise pollution on roads. This technology can be applied in various ways to create quieter environments for people living or working near busy roads.

One example of noise-cancelling technology is the use of sound-diffracting walls, which bend sound waves away from surrounding homes or other sensitive areas. These walls, such as those developed by the Dutch company 4Silence BV, feature grooves of varying depths that redirect horizontal noise upwards, reducing its impact on nearby residents. This technology has been successfully trialled in several European countries, including the Netherlands, Belgium, Germany, and Denmark, and is expected to be introduced more widely in the coming years.

Another noise-cancelling solution is the use of innovative algorithms that can adaptively follow changes in the noise spectrum. Silentium, a company specialising in active noise control (ANC), has developed such technology that can eliminate up to 90% of sound from various sources, including car engines and noisy trains. Their system creates Quiet Bubbles, providing individuals with personal zones of quiet. This technology is highly effective for low and medium-frequency noise and has been applied in various settings, including homes, offices, and the automotive industry.

In addition to these solutions, scientists are also developing noise-cancelling systems for open windows. This technology involves using a microphone to detect incoming sounds and an array of loudspeakers to emit sound waves with the same frequency but an opposing pressure pattern, effectively cancelling out the unwanted noise. This system has been shown to significantly reduce noise levels, providing a similar effect to closing the window. While further development is needed, this technology could be particularly beneficial in hot and humid climates, where natural ventilation is important.

Employ green infrastructure

Employing green infrastructure is an innovative and effective strategy to reduce noise pollution from roads and highways. This approach involves integrating natural elements, such as trees, shrubs, grasses, and wetlands, into the design of roads or as complementary elements along their edges. Green infrastructure can absorb, scatter, or deflect sound waves, reducing the impact of noise on nearby communities.

One successful example of green infrastructure is the use of vegetation barriers or "green walls". These barriers, constructed using materials like steel frames, glass fibres, and natural sound-absorbing materials such as coconut coir, can reduce noise levels by up to 13 decibels. The inclusion of vertical plants like Ficus pumila and ivy-leaf garland trees has been shown to further enhance noise reduction by up to 5 decibels. These types of green noise barriers not only mitigate noise pollution but also improve air quality, create habitats for wildlife, and provide aesthetic benefits.

Another way to employ green infrastructure is by creating green borders or corridors alongside roads. These vegetated areas can effectively absorb urban noises while also providing other benefits such as rainwater absorption and improved biodiversity. Green borders have been implemented in cities like Amsterdam, where a lawn has been incorporated along Sarphatistraat Street and Plantage Middenlaan to reduce noise levels.

In addition to vegetation, the use of natural materials for road construction can also contribute to noise reduction. For example, the use of low-noise pavement materials such as rubberised asphalt, porous asphalt, or stone mastic asphalt can reduce noise generated by tyre-pavement interaction. These pavement types also offer improved drainage, skid resistance, and durability of the road surface.

By employing these green infrastructure strategies, cities can reduce noise pollution from roads, creating healthier and more sustainable environments for their residents.

Engage with the community

Reducing road noise pollution requires the involvement of the community. Here are some ways to engage with the community and reduce noise pollution:

• Public education and awareness: Inform citizens, developers, and planners about the impact of road noise and the available solutions. Educate the community about the health risks associated with noise pollution, such as sleep problems, stress, and increased risk of heart disease.
• Involve residents, planners, and developers: Collaborate with the community to find solutions that work for everyone. Residents can provide input on the impact of noise in their daily lives, while planners and developers can incorporate noise reduction strategies into their designs.
• Community feedback and input: Encourage the community to provide feedback and suggestions on noise reduction measures. They may have insights or ideas that can improve the effectiveness of noise barriers or other strategies.
• Community events and workshops: Organize events or workshops to bring people together and discuss noise pollution. These events can help spread awareness, generate ideas, and create a sense of collective action.
• Community monitoring and reporting: Involve the community in monitoring noise levels and reporting noisy vehicles or areas of concern. This can help identify problem areas and ensure that noise reduction measures are effective.
• Community-driven solutions: Encourage and support community-led initiatives to reduce noise pollution. For example, communities can plant trees and shrubs to create natural noise barriers or advocate for noise-reducing infrastructure projects.

By engaging with the community and working together, we can find effective and sustainable solutions to reduce road noise pollution and improve the quality of life for all residents.

Frequently asked questions