Automakers operating in the US could be forced to fit artificial noise generators to new electric vehicles, a recent announcement from authorities has suggested.
The National Highway Traffic Safety Administration (NHTSA) said July 7 that it had launched an assessment of how best to introduce regulations that would protect "unsuspecting pedestrians and the visually-impaired from accidents involving hybrid and electric vehicles."
The sounds emitted by electric vehicles are becoming something of a safety headache for governments and automakers.
As the cars use an electric motor instead of a combustion engine, they are virtually silent at low speeds, posing a much greater risk to other road users - several studies have linked quiet hybrid vehicles with a higher accident rate than gasoline vehicles.
As a result, some automakers have bowed to pressure to add warning noises to their vehicles, at the risk of displeasing users who believe that a key advantage of electric motoring is the significant decrease in so-called "noise pollution."
The NHTSA will now evaluate the merits of a law compelling automakers to add artificial noise, with US Transportation Secretary Ray LaHood saying "as we improve the environment with cleaner cars, we must also consider how it affects those on bikes and on foot."
Both Europe and Japan have published guidelines suggesting that electric vehicles operating at speeds up to 20km/h (when tire noise becomes enough to provide a sufficient warning) should make sounds which change in volume or tone depending on the speed of the vehicle.
However, in both countries it is permissible for the driver to deactivate such a system, a rule which is reflected in the Nissan Leaf's operation and drew criticism from groups representing visually-impaired people.
Listen to the sounds the NHTSA is considering: http://www.nhtsa.gov/Laws+&+Regulations/Quiet+Car+Notice+of+Intent