Sound-diffracting walls and rubber-coated asphalt ingredients address the major environmental problem of traffic noise.
In cities across the European Union, noise, together with air pollution, poses a significant health risk. Efforts are underway to reduce a major source of both: traffic.
Noise is the number two environmental source of health problems, after air pollution, according to the United Nations World Health Organization.
In the European Union, 22 million people are chronically annoyed by environmental noise. And every year there are 12,000 premature deaths in the EU as a result of: prolonged exposure to environmental noisewhose traffic is one of the main sources.
But as with climate change, the EU’s fight against noise pollution involves not only mitigation, but also adaptation. While traffic can be scaled back through improved urban design, motorized transport will continue to generate noise and a key challenge is finding ways to reduce the impact on people.
Bart Willems has a role to play there. He’s excited about a type of wall that he says can unite people more than divide them.
Willems was involved in a research project to reduce nuisance noise from roads and railways by using barriers that deflect sound waves and divert them away from houses. The phenomenon is known as diffraction.
The goal was to address a serious but undervalued environmental problem by thinking differently. The two conventional methods are building concrete walls to block out noise and using materials for roads and railways that absorb the noise better.
‘Diffraction offers a third solution’, says Willems, whose Dutch company 4Silence BV de Horizon-funded WHISSPER project.
based in the Netherlands 4Silence has developed walls with grooves of different depths, which reduce horizontal noise by bending it vertically upwards. This means that smaller barriers can be used to divert more noise away from surrounding people.
‘If one of our walls is one meter high, it reduces the sound by seven to nine decibels,’ says Willems. ‘An ordinary screen would have to measure three meters to achieve the same effect.’
The WHISSPER project tested the technology with the idea of combating traffic noise through diffraction, starting in 2019 and ending earlier this year. With its sound-deflecting walls tested in the Netherlands, Belgium, Germany and Denmark, the company says the barriers are easy to install and maintain. It is now trying to go to market.
‘Since then, we have started our first commercial projects in the Netherlands’, says Willems. ‘And we want to further commercialize our walls in different countries.’
For these initiatives, 4Silence usually works together with local authorities such as the municipality of Eindhoven or the province of Utrecht. Commercial projects for the Augsburg State Building Authority and Transport for London have also started in Germany and the UK.
In the coming months, new buyers will be announced across Europe, with 4Silence also keeping an eye on customers in countries such as Belgium and Denmark.
Sound-diffracting screens also benefit government budgets because they are half the cost of traditional noise-reducing measures.
The public infrastructure wallet has already been stretched. Spending in Europe on abatement of road and rail noise amounts to approximately €5.4 billion per year, or 6% of the total annual expenditure for both modes of transport.
Nevertheless, people’s exposure to traffic noise is increasing in the EU. More than one in four Europeans are confronted with levels that are hazardous to health in homes, schools and workplaces.
Meanwhile, improvements in traditional methods of dealing with traffic noise are being sought on the mitigation front.
a separate one Horizon-funded project called SILENT RUBBER PAVE makes asphalt more spongy and hopefully quieter in an environmentally friendly way. The project involved a company based in Spain called Cirtec.
Cirtec is about to sell a new asphalt additive called RARx, which is made with rubber from end-of-life tires. RARx is added to asphalt to absorb some road traffic noise.
While applying rubber powder to asphalt has been tried before, practical challenges arose.
“In the past, contractors used to add the rubber compound directly to the asphalt, which caused a lot of problems,” says Guillermo Rodríguez Marfil of Cirtec. “It caused problems with the mix – and cleaning up the equipment after that was difficult.”
With RARx, the rubber powder is mixed in the factory with mineral additives such as bitumen, making it easier for asphalt manufacturers to use. According to Rodríguez Marfil, car noise is reduced by 4-5 decibels.
“The mix reduces the stiffness of the asphalt, which means less vibration in the tire and therefore less noise,” he said.
It can also extend the life of current roads, leading to lower maintenance costs. Furthermore, the whole concept is circular since the rubber mix is made from used tires.
RARx is being rolled out in Spain, among others. Tests and construction projects were also carried out in Germany, Italy, Portugal and Ireland, partly under the umbrella of SILENT RUBBER PAVE.
RARx is produced in Spain and, according to Rodríguez Marfil, will also be produced at a second plant under construction in Mexico, Cirtec’s largest market.
“The future looks bright,” he said. ‘We work on several continents and our impact is growing. We save governments money and reduce noise nuisance for citizens.’
In addition to finding markets for their new noise reduction tools, both Cirtec and 4Silence rely on regulatory changes to facilitate business growth.
Because roads are often built by governments and their subcontractors, the activity is highly regulated.
“In the paving industry, they’ve been doing the same thing for centuries, which is hard to overcome,” said Rodríguez Marfil.
Willems from 4Silence repeated the point.
“Infrastructure doesn’t move fast, especially when laws have to change before we can introduce our technology,” he said. ‘Still, we are optimistic that people in Europe will regularly see our barriers in the next three years.’
Noise pollution hurts animals, and we don’t even know how much
Quote: Reducing noise pollution with acoustic walls and rubber roads (2022, 21 October) retrieved 21 October 2022 from https://phys.org/news/2022-10-noise-pollution-acoustic-walls-rubberised.html
This document is copyrighted. Other than fair dealing for personal study or research, nothing may be reproduced without written permission. The content is provided for informational purposes only.