Electric vehicle alert signals: benefits and drawbacks

Photo credit: Olaf Arndt licensed under CC BY-NC-SA 2.0

by Daniel Fink, MD, Chair, The Quiet Coalition

This article in the current issue of Acoustics Today discusses electric vehicle noises, which are mandatory in the U.S. to alert blind and visually impaired pedestrians of approaching electric vehicles. Apparently an early study showed increased pedestrian accidents with electric vehicles, hence the federal mandate for vehicle sounds.

As discussed, the need for electric vehicles to make noise runs counter to the general push for highway quiet. Road traffic noise has been shown in multiple studies to cause increased morbidity and mortality. One of the most cited studies on this topic was done by Halonen and colleagues in London.

I walk almost every day, early in the morning, in the dark much of the year. My observation is that the major component of vehicle noise is tire noise, which can be heard from almost a block away. Engine or exhaust noise is a more noticeable component for diesel vehicles, or muscle cars and motorcycles with modified exhaust systems. When vehicles are starting from a stop, engine noise is more noticeable, but that is quickly replaced by the tire noise.

The mandatory electric vehicle noise may be important when an electric vehicle is starting from a stop, or especially when it is backing up and the driver may not notice a pedestrian behind the vehicle. As the article notes, the ultimate solution is collision avoidance systems that regardless of engine type will alert the driver to pedestrians and perhaps even stop the vehicle.  But it appears that most of the time, attention, and energy has been directed towards making electric vehicles emit noise, which to me seems to be a misguided effort. Among other things, can the deliberate noise compete with existing sources of vehicle noises, namely engine, exhaust, and tire noise?

I wish more attention were directed at these very real problems, rather than towards what to me seems to be largely a theoretical problem.

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