6 February 2020

Noise engin-ear

Our cities are alive with the sound of... cars. From sound barriers to silent tyres, we learn how Riga is turning down the volume.

Riga

Mobility

The vroom of cars, the woosh of airplanes, the clatter of trains and trams on their tracks – our cities are symphonies, but sometimes we would prefer it if the curtain dropped for a while. Cities all over Europe are working to turn down the noise, and Riga is one city that is taking serious action.

More than a nuisance

 

Noise can be more than a nuisance, it actually has documented deleterious effects on human health. According to the World Health Organisation, noise can contribute to heart problems, damage to the hearing and even cognitive impairment. They calculate that noise pollution is responsible for a disease burden that is second only to air pollution.

To begin its battle against noise, Riga worked to understand its enemy, mapping out the noise profile of the city so that it could better determine the causes of, and thus the solutions to, noise. The results showed that during the day-time about one tenth of the city experiences noise above the legal limit, while in the evening and during the night this figure nearly doubles.

Public enemy number one

“One of the chief offenders was traffic”

Once the areas suffering from excess noise were revealed, the culprits were clear. “One of the chief offenders was traffic,” says Miervaldis Lācis of Riga City Municipality, “so we could tackle noise together with other mobility issues like pollution and placemaking.”

As with air pollution, private cars and freight transport were one of the biggest issues. “Our mission is to get these out of the city wherever possible,” Lācis says. That includes building new ring roads and overpasses for traffic that does actually have a purpose within the city limits.

For those that actually have business in the city, new ‘park and ride’ facilities are being opened up. ‘Park and ride’ refers to building large parking spaces near transport nodes like train and bus lines so that people can drive from more remote areas but stop short of hitting the city traffic, easily streaming into public transport on the outskirts of town.

Railing against noise

Cars are not the only things that are being redirected. Although trains are becoming a fashionable solution to high-carbon travel, this doesn’t make them any less noisy. That is why Riga has upgraded some of the train tracks that are situated further from urban life to allow freight trains to bring their cargo from A to B without taking the same path as the commuter trains that necessarily find themselves in densely populated parts of the city.

However, says Lācis, “a city would not be a city without people and goods moving around, so we will always need some cars, trams and buses.” Where moving the vehicles further away is not possible, the solutions start to get more complex.

“Sound travels in waves, so you can build a dam”

“Sound travels in waves, so you can build a dam, just like you would with water,” Lācis says, of the sound barriers that the city has erected along its noisier routes. But while this solution is simple, its main effects are only for those closest to the noisy area, the difference begins to level off as you move away from the noise source.

Good vibrations

But rather than blocking the noise, you can also do a lot reduce it at the source. For example, the city has invested in new low-floor trams, as these have a lower noise footprint than traditional models.

“you get a double win”

“Like almost anything you do to tackle noise,” Lācis boasts, “you get a double win. In this case, the new design greatly improves accessibility, especially for people with impaired mobility.” New tram tracks with better absorption and less vibration are also part of the picture.

Tyred of cars

The solutions get even more technical. The city has gone as far as rebuilding some road infrastructure with ‘quiet asphalt’. This special surface comes in many different varieties, including a type that is actually made with rubber crumb from used car tyres. Tyres are very difficult to recycle, and, since the EU made this process mandatory, people have been scrambling for good ways to bring tyres around to the circular economy.

Adding this material to road surfaces can make it more buoyant, which means less vibration from cars, and it also makes roads safer by reducing the likelihood of skidding in wet weather conditions. “Another double win,” Lācis points out proudly.

Municipal vehicles, including public transport, are complimenting this approach with special ‘quiet tyres’. Another impressive technical innovation, these tyres have specially shaped tread tracks designed not to trap air inside them. A lot of the noise that comes from cars is related to the compression and decompression of air in the tyre tread as it rolls along the street under the weight of the car’s body.

Our friends electric

“it could be just like a horror movie”

“The soundtracks for horror movies like Jaws use a lot of high and low notes because high notes remind us of animals in distress and put us on edge, while low notes typically come from big animals that can be a source of danger. All those cars rumbling and their breaks screeching – it could be just like a horror movie! We are really doing a lot to get those things out of the city,” Lācis exclaims.

Part of this effort as been a big drive to push people to chose electric rather than diesel engines. The city is doing this by investing in more charging infrastructure, so that people can always feel confident about driving out on battery power. Electric cars also get free parking in municipal parking lots, which is a big bonus when you drive into town to do your shopping.

Oldschool

“But you don’t have to go into the future,” Lācis says, “sometimes the old methods like walking and cycling are best.” Riga is making cycling easier by building more and better bike lanes, and using campaigns to popularise active travel, as well as to educate other road users about respecting their two-wheeled companions.

Riga is not going it alone. The city is cooperating in its work on cycling with the national level, working within the new Latvian cycle plan. It is also working with its airport to encourage investment in quieter models of airplanes.

Good neighbours

The building stock in Riga is also getting in on the action, with energy-saving thermal insulation in new and retrofitted buildings often being paired with acoustic insulation that will help the residents get a good night’s sleep, and stay on good terms with their neighbours.

“Understand your enemy”

But the city is also going a step beyond the inanimate, investing not just in vehicles and buildings, but also in its people. Earplugs distribution centres? “No, this is a long-term investment in increasing the capacity of city staff. To win a battle, you have to understand your enemy. We’re training up municipal staff to understand noise better.”

Training ranges from noise action planning to building acoustics and acoustic spatial planning, so more future decisions can be made with noise in mind. They say that silence is golden, and this 304 km2 capital city aspires to be worth its weight in gold.

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