Many drivers choose hybrid cars not only for their fuel economy, but also because they run more quietly than traditional cars. But how quiet is too quiet? After spending decades trying to figure out how to make cars quieter, automakers and drivers are discovering that cars that are too quiet can be dangerous. Often, the noise of an oncoming vehicle can help prevent an accident with a pedestrian. Yet when hybrid cars are run at low speeds, before the combustion engine kicks in, they run nearly noiselessly, leaving pedestrians at risk of being surprised by an oncoming car. A study by the National Highway Traffic Safety Administration (NHTSA) has showed that hybrid cars are 50 percent more likely to be involved in accidents with pedestrians when operating at lower speeds.
In an effort to reduce such accidents, Rep. Edolphus Towns (D-N.Y.) has introduced a bill which would require the establishment of a safety standard for cars to be equipped with “non-visual alerts.” These alerts would allow pedestrians to judge the vehicle’s location, direction, and speed.
It is still unclear what the required noise should be, however. Some auto manufacturers are working to develop sound that will both alert pedestrians and provide the car with an audio signature. Advocates for the blind however, say that electric cars should make similar noises to gas-powered cars, in an effort to avoid confusion. If the bill becomes law, automakers will be subject to both government regulation and consumer preference, given that some consumers may not want a car that makes an unusual noise. Nissan has proposed three new sounds to the NHTSA, including a chime, a melody, and a whirring sound. Over the next few years, automakers and regulators will likely be experimenting with what will be safest, in addition to what will be more marketable to drivers.