The European Union has implemented a new mandate requiring all new electric vehicles be fitted with a device that emits a noise at speeds of 12 mph and under.
These noise producing devices serve as a pedestrian device. Because EVs are almost silent when driving slowly or accelerating from a stop, pedestrians may not hear them coming and step into their path.
The EU mandate does not require that the noise sounds a certain way, although there is a frequency range it must fall within. Additionally, the sound must change pitch when accelerating or decelerating. It must also have a volume of at least 56 decibels. An average internal combustion engine vehicle rings in at about 80 decibels.
“The sound to be generated should be a continuous sound that provides information to the pedestrians and vulnerable road users of a vehicle in operation,” the EU guideline says. “The sound should be easily indicative of vehicle behaviour and should sound similar to the sound of a vehicle of the same category equipped with an internal combustion engine.”
Noise emitting devices will also be able to be overridden for certain scenarios, like driving stop and go traffic on the highway, for example.
Advocate groups for the blind and those with poor eyesight have called for a such a mandate in the past.
The US National Highway and Traffic Safety Administration will implement a mandate similar to the new EU guidelines by 2020. Under those rules, all electric and hybrid cars must emit warning sounds when travelling below 18.6 mph by 2020.