When noise is a problem, it’s usually in the “too much” rather than “too little” category.

The opposite is true of ultra-quiet electric and hybrid vehicles, who emit so little noise at low speeds that pedestrians and bicyclists may not be able to detect their presence, thus increasing the chance of an accident occurring.

As required by the Pedestrian Safety Enhancement Act of 2010 (PSEA), the U.S. Department of Transportation’s National Highway Traffic Safety Administration (NHTSA) is proposing that hybrid and electric vehicles meet minimum sound standards in order to help make all pedestrians more aware of the approaching vehicles.  

The proposed standard, Federal Motor Vehicle Safety Standard No. 141, would mandate that hybrid and electric vehicles meet minimum sound requirements so that pedestrians are able to detect the presence, direction and location of these vehicles when they are operating at low speeds. 

“Our proposal would allow manufacturers the flexibility to design different sounds for different makes and models while still providing an opportunity for pedestrians,  bicyclists and the visually impaired to detect and recognize a vehicle and make a decision about whether it is safe to cross the street,” said NHTSA Administrator David Strickland.

The sounds would need to be detectable under a wide range of street noises and other ambient background sounds when the vehicle is traveling under 18 miles per hour. At 18 miles per hour and above, vehicles make sufficient noise to allow pedestrians and bicyclists to detect them without added sound. Each automaker would have a significant range of choices about the sounds it chooses for its vehicles, but the characteristics of those sounds would need to meet certain minimum requirements. In addition, each vehicle of the same make and model would need to emit the same sound or set of sounds.

NHTSA estimates that if this proposal were implemented there would be 2,800 fewer pedestrian and pedalcyclist injuries over the life of each model year of hybrid cars, trucks and vans and low speed vehicles, as compared to vehicles without sound.