Fight fire with fire? Wavebreaker dampens traffic noise from railways using noise

Earlier this year, Swedish startup Wavebreaker started operations with the launch of its traffic noise sound damper of the same name. Founder and developer of Wavebreaker Tony Johansson spoke with RailTech.com about the system and the benefits thereof.

For Johansson, Wavebreaker is the culmination of more than 32 years of experience in the field of acoustics. Back in 2017, he took the plunge by starting his own business. With support of Swedish business incubators such as Almi, Vinnova and InfraSweden2030, Johansson was able to perfect his Wavebreaker prototype ahead of installation as part of a pilot project in Stockholm.

Wavebreaker utilises the principle of acoustic interference, where noise enters a series of channels of varying length before coming out at the other end. With Wavebreaker, this means noise from a passing tram or tram enters at the front and exits at the top. There it ‘interferes’ with the noise travelling over the Wavebreaker. In doing so, the so-called noise paths cancel each other out.

“It’s bit like what you get with noise cancelling headphones, but then without the need of a power source. It is a passive system and as such only needs the input of traffic noise to function”, Johansson explains. Wavebreaker is optimised for reducing train noise by focusing on the spectrum between 400 to 4000 Hz.

Immediate solution

During trials in Stockholm in August 2021, Wavebreaker resulted in a noise reduction of 5 dBA. Also in terms of psychoacoustics, or the way humans perceive sounds, there was a marked improvement. “The familiar high-pitched rattling sound that you associate with trams of trains was softened with Wavebreaker”, Johansson says.

Simply put, if Wavebreaker is installed on an existing noise screen or sound barrier, it will only add 20 centimetres in height but it will have the same effect as increasing the height of the screens by 1-2 metres depending on ambient factors. This, then, opens op a world of opportunities.

“Installing Wavebreaker will therefore be cheaper compared with building taller noise screens. And because you have a more unobstructed view with Wavebreaker, you get less of a corridor effect along the tracks”, Johansson explains.

Lastly, if for whatever reason a noise screen is not performing as intended – be it because of faulty calculations or otherwise – the problem can be easily be remedied by adding Wavebreaker. “This means an immediate solution and eliminates the need for costly and time-consuming investigations into the root of the problem.”

The Wavebreaker units are lightweight, easy to install and relatively compact (image: Wavebreaker).

Expected lifespan of some 50 years

With the pilot project now completed, Johansson and Wavebreaker are targeting their first installation job. “We have a production capacity of 1,000 metres per week, so we’re ready for quite a high starting volume”, he says, adding that there might be another test project in the Nordic area in the works. The plastic Wavebreaker units are light weight yet durable, containing more than 50 percent recycled material, with an expected lifespan of some 50 years.

“It’s very exciting yet challenging to get a new product to market in the railway industry, which tends to be a bit conservative. On top of that, the tendering process is not always easy for newcomers. You really need to learn how different markets function, what the processes are and what kind of approvals you need”, says Johansson.

Yet as Eurocities, a European network of more than 200 cities that focuses on increasing the quality of living, recently pointed out: more than 100 million Europeans are affected by harmful noise pollution. As a result, European cities now more than ever, are geared towards tackling noise pollution. Wavebreaker might just be the product to help them do it.

Tony Johansson and Wavebreaker are among the exhibitors at the upcoming RailTech Europe conference & exhibition. Would you like to experience and learn more about the latest technological developments in the rail industry? Join us!

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Author: Nick Augusteijn

Editor RailTech.com

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