The US DOT has finalized rules that will require “quiet cars” (electrified vehicles) to emit “alert sounds” to warn pedestrians of their approach.

The long-delayed rules, which were mandated by Congress in 2010, will require electrified vehicles to generate sounds when moving at speeds of up to 18.6 miles per hour. At higher speeds, according to regulators, tire and wind noise make artificial sounds unnecessary.

The new regulation requires automakers to add the sounds to 50 percent of vehicles by September 2019, and to all vehicles by September 2020. Regulators said they will consider a request from automakers to allow car owners to select from multiple sounds.

The National Highway Traffic Safety Administration (NHTSA) says it expects about 530,000 model 2020 vehicles to be affected. NHTSA says the rules will cost the auto industry about $40 million per year, as automakers will need to add an external waterproof speaker to comply. However, the agency predicts the new rules will prevent 2,400 injuries annually, saving between 250 million and 320 million dollars.

NHTSA estimates that the odds of a hybrid vehicle being involved in a pedestrian crash are 19 percent higher than those of a legacy vehicle. About 125,000 pedestrians and cyclists are injured each year on US roads.

“This rule strikes the right balance for automakers and for the blind community,” said Gloria Bergquist, a spokeswoman for the Alliance of Automobile Manufacturers.

Source: Reuters