Electric Vehicles – noise reduction, noise production?

URBACT

By URBACT, on June 8th, 2011

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Alongside a cooling of urban relations with the motor car, through the years there have been many sound arguments put forward supporting moves to revolutionise mobility management in our cities. The increasing interest in applying traffic calming measures has been provoked by the need to counter the paralysing  impacts of congestion but also as a result of concerns raised in connection with road safety, pollution, visual and spatial hindrance, etc. The aspect of noise generated by traffic was also part of this consideration, but often appearing subordinate as citizens seemed almost to have been conditioned to accept this as part of normal urban life.  Nevertheless EU figures suggest, that as a result of road traffic alone, during daytime around 40% of the population are exposed to noise levels exceeding 55dBA (30% night time) and 20% are exposed to levels higher than 65dBA. While it might be argued that in itself, this does not constitute a “harmful” level of exposure, it is a serious part of total urban noise production and in many cases the noise generated by road traffic is continuous and therefore more than simply intrusive or annoying.

Renewed, and today truly operational, interest in electric (and hydrogen powered) vehicles presents us with a new weapon to tackle the problems of traffic related noise. While vehicle noise is  the sum of noise produced through moving contact with the road surface together with engine noise, still the relative silence of the electric motor has real potential to seriously reduce noise levels in our cities (even although technological advancement is also improving this feature in fossil-fuelled vehicle engines).

It seems strangely incongruous then, that the benefits of silent locomotion may have to be offset against the objectives of one of the other traffic calming motives, namely road safety. A study currently being conducted at the University of Warwick is researching the introduction of an artificial noise component to diminish possible dangers of the silent vehicle particularly for key risk groups, the elderly, children and people with reduced sight capacities. The project is testing an electric vehicle, ELVIN (Electric Vehicle with Interactive Noise) using various noise options in an attempt to find new reduced sound levels, but simultaneously which emit the necessary warning signal (presence, speed and acceleration) which people associate with approaching vehicular transport.  Synthetic noise linked to motor power is being evaluated here, but reactions indicate that options (even considerations of music) and opinions differ greatly both on questions of necessity and on the most effective sound type. There have been suggestions to adjust the use of sound to times of day, to specific types of urban landscape (around schools). Similarly the operation of sounds could be linked to speed or smart GPS systems, while many manufacturers will probably prefer a sound which corresponds to the image of the vehicle they want to project.

This suggests that there are many questions to be answered and that the search to find an optimal, broadly accepted solution(s) will be an extremely delicate exercise. However the results of this study which also employs people with impaired vision as privileged test cases, can have a useful input to EU legislation on electric and hydrogen car sounds which is currently in stages of preparation.

Why not try evaluating ELVIN yourself by following the link.

Some other relevant projects on traffic noise in the EU:

Philip Stein
Thematic Pole Manager

3 Responses to “Electric Vehicles – noise reduction, noise production?”

  1. CityHush is another project aiming to reduce noise in traffic: http://cityhush.eu/

  2. excellent ! i have not seen such article superb

  3. click here says:

    Very interesting project!

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