In an effort to prevent injuries among pedestrians, the U.S. government has finalized rules that require quiet hybrid and electric vehicles to emit alert sounds when they are traveling at low speeds. Reuters reports: The rules, which were required by Congress, will require automakers like Tesla Motors Inc, Nissan Motor Co and Toyota Motor Corp to add the sounds to all vehicles by September 2019. The U.S. Transportation Department said it expects the rules would prevent 2,400 injuries a year by 2020 and require the addition of alert sounds to about 530,000 2020 model vehicles. The U.S. National Highway Transportation Department said the rules will cost the auto industry about $39 million annually because automakers will need to add an external waterproof speaker to comply. But the benefits of the reduced injuries are estimated at $250 million to $320 million annually. NHTSA estimates the odds of a hybrid vehicle being involved in a pedestrian crash are 19 percent higher compared with a traditional gas-powered vehicle. About 125,000 pedestrians and bicyclists are injured annually. The rules will also help the blind and visually impaired. The rules apply to hybrid and electric cars, SUVs, trucks and buses weighing up to 10,000 pounds and seek to prevent crashes at intersections or when electric vehicles are backing up. At higher speeds, the alert is not required because other factors like tire and wind noise adequately warn pedestrians, NHTSA said.