The proposed new hybrid and EV sound standard is intended to meet with the US Congress' mandate in the Pedestrian Safety Enhancement Act in regards to minimum vehicle sound requirements, to make pedestrians more aware of approaching vehicles and detect the presence, direction and location of vehicles when being operated at lower speeds.
US Transportation secretary Ray LaHood said the proposal would help keep everyone using US streets and roadways safe. "Safety is our highest priority … whether they are motorists, bicyclists or pedestrians, and especially the blind and visually impaired," LaHood said.
NHTSA administrator David Strickland said that under the proposal manufacturers would be allowed the flexibility to design different sounds for different makes and models, provided they still gave pedestrians, bicyclists and the visually impaired the opportunity to detect and recognise an approaching vehicle and make a decision about whether it is safe to cross a street.
The NHTSA says the generated sounds would need to be detectable under a wide range of street noises and other ambient background sounds when the vehicle is traveling under 29km/h, as above this speed, vehicle noise is sufficient to allow pedestrians and bicyclists to detect them without added sound.
The safety administration notes that while each car maker would have a significant range of choices about the specific sounds it chooses to use for its vehicles, the characteristics of those sounds would need to meet certain minimum requirements themselves and each vehicle of the same make and model would need to emit the same sound or set of sounds.
The NHTSA estimates that if the proposal were implemented, 2800 fewer pedestrian and pedalcyclist injuries would occur over the life of each model year of hybrid cars, trucks, vans and low speed vehicles, compared with vehicles that are without sound.