The U.S. Department of Transportation has finalised legislation declaring that quiet vehicles such as electric and hybrid cars must make some kind of noise at low speeds to alert pedestrians, cyclists, and the blind to their presence.

Half of all hybrid and electric cars are requires to comply with the new rules by 1^st September 2019, with the rest to be in compliance by 2020.

At speeds below 18.6 mph, these cars will be required to emit some kind of noise to make their presence better known to others in the surrounding area. At higher speeds noise from the tires, wind, and elsewhere makes these devices unnecessary.

The NHTSA says that the new rules will help prevent 2,400 injuries each year by 2020. The agency expects about 530,000 quiet vehicles will be equipped with audible alerts by 2020 at a cost of $40 million annually.