Right to Quiet Society Noiseletter
Fall 2013, page 5

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Are vehicles driven in electric mode so quiet that they need acoustic warning signals?

Proceedings of 20th International Congress on Acoustics,
23-27 August 2010, Sydney, Australia (ICA 2010 1)

Ulf Sandberg 1, Luc Goubert 2 and Piotr Mioduszewski 3
1 Swedish National Road and Transport Research Insti-tute (VTI), Linköping, Sweden
2 Belgian Road Research Centre (BRRC), Brussels, Belgium
3 Technical University of Gdansk (TUG), Gdansk, Poland

ABSTRACT

It has been suggested recently that vehicles, driven in electric mode, either hybrid or pure electric vehicles, are so quiet that they constitute a safety hazard for pedestrians and bicyclists in traffic. It is claimed that such vehicles are not acoustically perceived due to the power unit being exchanged from a combustion engine to electric motors; something that essentially cuts away all power unit noise and leaves tyre/road noise, the latter of which is the same as for similar-sized vehicles with combustion engines. There are currently a number of fast and concerted actions by the US and Japanese governments as well as within international bodies such as UN/ECE and ISO, with the expected outcome that "minimum noise" of vehicles shall be measured with a standard method and legal limit values for such "minimum noise" shall be established. The paper presents findings regarding possible traffic safety effects

of quiet vehicles and concludes that only a US study has identified such effects. A critical review leads to the conclusion that this study may be biased and needs confirmation by further research. After reviewing data from noise measurements in Japan, the authors present their own previously unpublished data on noise emission levels for road vehicles which may be considered as "quiet". Special concern is given to noise at speeds below 20 km/h where it is expected that the problem might be the worst and where previous data are missing. It is concluded that already a significant number of our present internal combustion engine vehicles are so quiet at low speeds that normally one cannot hear any difference between an electric and a normal vehicle in an urban area. Tyre/road noise is the dominating noise in most cases where a light vehicle is driven at speeds at or above 15-20 km/h (heavy acceler-ations are the exceptions), and this is the same whether the vehicle is electric or not. Thus, it is a property of our vehicle fleet which we have had for more than a decade, and few have considered that as a safety problem. Therefore, there is not enough justification for equipping our future quiet vehicles with extra artificial noise or warning sounds. If needed at all, there are better options which are non-acoustical.

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Noise pollution can lead to heart disease

A German study - using data from the German Heinz Nixdorf Recall Study - has shown that noise pollution from prolonged exposure to heavy traffic can cause heart disease. The study was aimed at assessing whether noise pollution or particle pollution from traffic attributes to atherosclerosis.

Atherosclerosis is a narrowing and hardening of the arteries due to a build-up of plaque around the artery walls. This can cause heart attacks and other cardiovascular complications as it disrupts the blood flow around the body.

The study included 4,814 participants living in close proximity to busy roads. It is the first time that a cardiological study has taken road traffic noise pollution into account in terms of its effect on heart disease. 4,238 of the subjects experienced an increase in aortic calcification related to both noise pollution and air pollution. Calcification increased by 20.7 per cent for every 2.4 micrometer increase in particle volume, alongside an extra ten per cent increase in calcification for every 100 metres of proximity to heavy traffic.

Dr Hagan Kalsch, from the West-German Heart Centre in Essen, said: "These two major types of traffic emissions help explain the observed associations between living close to high traffic and subclinical atherosclerosis. The considerable size of the associations underscores the importance of long-term exposure to air pollution and road traffic noise as risk factors for atherosclerosis."

Both aspects of prolonged exposure to high levels of traffic independently explain how living near roads is often linked to heart disease. Noise pollution and air pollution - it is believed - both work through the same biological pathways, which is why they, individually, increase the chances of the same type of heart disease. An imbalance is caused in the autonomic nervous system, which affects the mechanisms that regulate glucose level, blood pressure and blood lipids.

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Hush those engines: noisy bikes targeted

By Emily Jackson, Metronews.ca (excerpts)

Stop revving those engines. Dozens of complaints about excessively noisy motorcycles and cars led the Vancouver police to target obnoxiously loud drivers over the weekend. Of approximately 50 vehicles tested, 19 were too loud and received $190 tickets on an order to have the muffler


repaired, Sgt. Derral Daniels said at a news conference.
Police pulled over a motorcyclist who didn’t hear the siren for two blocks because his motor was so loud. The loudest bike they pulled over was 112 decibels. “Not loud bikes but safe driving safes lives,” Daniels emphasised.



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