Electric Cars = Quiet Roadways? Not so Fast…

Steph Willems
by Steph Willems
electric cars quiet roadways not so fast 8230

Because we’ll all be travelling around in autonomous electric pods any day now, more and more people want to know whether they’ll be able to hear a pin drop on the sidewalk once those nasty internal combustion vehicles are extinct.

Well, if it’s serene, pastoral bliss you’re looking forward to, don’t expect to find it anywhere near a freeway. The folks at Clean Technica looked at the best studies available on the issue, and the results are bad news for those who think “EV” is another word for “whisper.”

No longer as rare and exciting as when the first models hit the market, electric vehicles still make up only a tiny sliver of overall market share. But the day might come when we’re all dependent on ions for propulsion, instead of evil hydrocarbons.

In order to prevent the crushing of small children and other bipedal creatures in urban environments, EVs emit a a high-pitched whine that doesn’t travel very far. They’re infinitely quieter than revving gas engines, booming diesels and the symphony of stressed exhaust systems.

So, yes — at low speeds, EVs are quiet as hell. But there’s so much else to the picture.

First, think of what you hear right now. Traffic has always been this noisy, right? Wrong. Advancements in engine and tire technology means today’s vehicles are far quieter than those produced even a few decades ago. You’re already hearing less noise than you used to.

But back to EVs. While EVs emit next to no engine noise, that’s their only saving grace. As speeds rise, a gas-powered vehicle’s engine noise falls as a percentage of overall noise, and tire noise picks up. Two highway traffic noise studies published by researchers in the U.S. and Netherlands show an insignificant gap between tire noise and overall noise at highway speeds.

EV tires aren’t magical — they’re made of the same stuff as every other tire. And that abrasive rubber is rolling along an imperfect surface made of asphalt.

The U.S. study found that aerodynamic noise — the sound made by a vehicle pushing air out of its way — outweighs engine noise in internal combustion vehicles at speeds above 110 kilometers per hour (68 mph). Even at low speeds, tire noise outweighs engine noise by a factor of 2:1.

In fact, tire noise and overall noise were so closely tied, the difference between the two wouldn’t be noticeable to the human ear (less than three decibels).

The Dutch study, which used different methodologies, backs up most of the U.S. findings. At 25 miles per hour, engine noise is slightly higher than tire noise, but both are outweighed by overall “road noise.” Once speeds hit 43 mph (70 km/h) engine noise was nearly half of the noise emitted by tires. At 60 mph, engine noise has little significance.

So, while there’ll be less “sharp” sounds in our electric future — tire chirping, revving, and obnoxious mufflers — overall highway noise will continue with little change. Your emissions-free Tesla, Bolt, Leaf or whatever comes next will keep oil in the ground, but it won’t stop noise pollution.

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  • Raph Raph on Jun 07, 2016

    I figured it would be tire noise. That's what I mostly hear from the majority of vehicles on the road. Especially people who neglect to rotate their tires or do not rotate them correctly (looking at the buffoons that rotate only front to back and the tires end up cupping as a result - because you know like changing out that winter and summer air you should never cross-rotate radial tires!)

  • Sector 5 Sector 5 on Jun 07, 2016

    Sirens - when we do go fully self driving let's convert them back to bells.. Well done Japan keeping your fire truck bells for gentler occasions.

  • Denis Jeep have other cars?!?
  • Darren Mertz In 2000, after reading the glowing reviews from c/d in 1998, I decided that was the car for me (yep, it took me 2 years to make up my mind). I found a 1999 with 24k on the clock at a local Volvo dealership. I think the salesman was more impressed with it than I was. It was everything I had hoped for. Comfortable, stylish, roomy, refined, efficient, flexible, ... I can't think of more superlatives right now but there are likely more. I had that car until just last year at this time. A red light runner t-boned me and my partner who was in the passenger seat. The cops estimate the other driver hit us at about 50 mph - on a city street. My partner wasn't visibly injured (when the seat air bag went off it shoved him out of the way of the intruding car) but his hip was rather tweaked. My car, though, was gone. I cried like a baby when they towed it away. I ruminated for months trying to decide how to replace it. Luckily, we had my 1998 SAAB 9000 as a spare car to use. I decided early on that there would be no new car considered. I loathe touch screens. I'm also not a fan of climate control. Months went by. I decided to keep looking for another B5 Passat. As the author wrote, the B5.5 just looked 'over done'. October this past year I found my Cinderella slipper - an early 2001. Same silver color. Same black leather interior. Same 1.8T engine. Same 5 speed manual transmission. I was happier than a pig in sh!t. But a little sad also. I had replaced my baby. But life goes on. I drive it every day to work which takes me over some rather twisty freeway ramps. I love the light snarel as I charge up some steep hills on my way home. So, I'm a dyed-in-the-wool Passat guy.
  • Paul Mezhir As awful as the styling was on these cars, they were beautifully assembled and extremely well finished for the day. The doors closed solidly, the ride was extremely quiet and the absence of squeaks and rattles was commendable. As for styling? Everything's beautiful in it's own way.....except for the VI coupe....it's proportions were just odd: the passenger compartment and wheelbase seemed to be way too short, especially compared to the VI sedan. Even the short-lived Town Coupe had much better proportions. None of the fox-body Lincolns could compare to the beautiful proportions of the Mark V.....it was the epitome of long, low, sleek and elegant. The proportions were just about perfect from every angle.
  • ToolGuy Silhouetting yourself on a ridge like that is an excellent way to get yourself shot ( Skylining)."Don't you know there's a special military operation on?"
  • ToolGuy When Farley says “like the Millennium Falcon” he means "fully updatable" and "constantly improving" -- it's right there in the Car and Driver article (and makes perfect sense).