This Tesla might be the first EV to comply with the new federal safety standard. It raced at this year’s Pikes Peak International Hill Climb, which requires electric vehicles to announce their presence with a siren or other audible warning for corner workers. (credit: Elle Cayabyab Gitlin)

Way back at the dawn of the automobile, people were skeptical of the new invention. They were accustomed to horses, and the UK passed a law that required motorists to be preceded by a man on foot waving a red flag so as to warn pedestrians.

Well, a 21st-century equivalent of that practice is on the way. A new rule announced by the National Highway Traffic Safety Administration on Monday will require electric vehicles (plug-in hybrid EVs as well as battery EVs) to make some noise at low speed to warn oncomers.

At speeds of 19mph (30km/h) or below—either moving forward or in reverse—EVs will need an audible warning. Above that speed, a warning is not considered necessary because tire and wind noise should provide sufficient notice to the visually impaired that a vehicle is headed their way.