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In Defense of Electric Silence

by Brian Dunning

October 19, 2014

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Donate For some time now, a few activists have proposed that a danger of electric cars is their silence to unsuspecting pedestrians. According to this claim, pedestrians are more likely to be struck by cars that they cannot hear coming. A suggested solution has been to add artificial noise to electric cars, supposedly making them less dangerous to semi-conscious pedestrians, and definitely making them annoying to everyone else. Having been both a pedestrian and a driver in my life, I am not a fan of this proposal.

Not incidentally, this proposal has existed since long before there were enough electric cars on the road that empirical data could have existed to prove this problem was anything but imaginary.

Wherever the legal responsibility may lie for the safety of pedestrians, the real responsibility is shared between the people who cross streets and parking lots, and the drivers who shouldn't hit them. As a driver (always of an internal combustion vehicle to date), I have, on many occasions, stomped on the brake to avoid striking someone who stepped out in front of me on a road, or behind me in a parking lot. In not a single instance have I ever elected to continue on a collision course and depended on the pedestrian to note my approach and step out of the way. I suspect this aversion to running people over is not unique to us drivers of fuel burners, but is also found among drivers of electrics. Unfortunately, people do sometimes step into harm's way by accident.

If you've ever stood beside a road, you've heard cars approach and drive past. You know that engine noise is almost always inaudible until the car has gone by. The roar of traffic consists entirely of tire and wind noise. Pause at a crosswalk the next time you get a chance and listen: gas-powered cars approach every bit as devoid of engine noise as electrics. Tire noise drowns it out completely. A pedestrian who steps into a street of fast-moving traffic had better rely on his eyes as well as his ears. Looking both ways before crossing is the pedestrian's best shot at upholding his half of the responsibility.

But sometimes he's paying more attention to his iPhone than to traffic and he's not being responsible. SHould we let the Darwin Effect preside? Nay, say all reasonable pundits. Let's put speakers blaring electronic engine noise onto the front of some cars. But which cars? All electric cars, regardless of the sound output of their tires, or cars that approach quietly? By no means are these to sets of cars the same. A pedestrian-smearing 600 class Mercedes-Benz comes a lot quieter than you might think.

There are environments where electric cars are nearly always quieter than internal combustion, and where pedestrians abound: the slow-speed worlds of parking lots. Here, tire noise (which generally increases exponentially to vehicle speed) is usually below the threshold of engine noise. Here it might make sense for all cars, in both forward and reverse, to emit a minimum required noise level. Such a law that applies to all cars would be far more sensible than "All electric cars should emit fake engine noise, at all times, regardless of all other factors." The question then becomes whether anyone would vote for such a comprehensively fair law. It's one thing to demand that those damn electric-car-driving hippies should have noisemakers affixed to their cars, and quite another to be told that you must also affix one to your Cadillac, and also that you must be exposed to a sea of cacophony in every supermarket parking lot.

I am not convinced that any such law would create a statistically significant reduction in pedestrian casualties. People have always been hit by cars, even before they had phone screens to distract them from looking, and before they had headphones to distract them from hearing. Drivers also have similar new distractions, but fake-noise generators would not impact driver attentiveness (though other systems can). Fake engine noise is (or should be) doomed to failure because it's based on a misguided understanding of the ways approaching cars produce noise.

Enjoy the silence inside your electric ride (or your gas-powered Toyota, for that matter). And please continue not running over people.

by Brian Dunning

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