I’ve lived in a few apartments that were situated along busy roads. Something like this would be nice, but I’m hopeful that we’ll someday get to a point where (almost) all of the vehicles on our roads will be electric. Has anybody worked out how much of a noise reduction we can expect from that?
In my experience (living a mile away from a motorway), most of the noise is caused by the wheel bearings of badly maintained lorries instead of tires. One can usually tell by the high pitched noise.
I'm surprised that noise propagates far enough for you to hear. In my experience, the noise that propagates furthest from roads is the low frequency tire rumble.
Noise is a complicated thing. If you're in a neighborhood that's got low-speed traffic and the occasional car engine is what's disrupting your peace, more penetration of EVs will be great. But EVs are also heavy, and cars are getting heavier in general. That isn't going to do you any favors on tire noise. I wouldn't expect the noise coming off of a freeway to change much.
Here in Germany they have deployed so-called "whisper/porous asphalt" on the highways leading into some major city centres. Since it's more porous than regular asphalt it absorbs noise (and rain) much better, but the drawback is that it's more expensive to manufacture and is less durable.
Just saying that there are probably lots of different noise reduction techniques that all add up their percentages, but these will only be put in place if noise pollution is taken as serious as it needs to be.
My (US) state DOT paved over the concrete highways with rubberized asphalt for similar reasons. The asphalt doesn’t last as long, but it’s quieter and cheaper than concrete repairs. It’s also something that uses up old tires.
Personally, I would favor "noise tax" for any noise generated, regardless of the reason. (I may be biased, I am noise-sensitive.)
In this case, it will put pressure to avoid, or reduce, noise when possible (as it directly lowers costs).
It's not only cars - all neighbors with a passion for loud music (or quarrels), repair works taking longer and louder than necessary.
I absolutely detest Harley's and other loud motorcycles and don't understand why there are no restrictions on vehicular noise. Why do certain individuals get to impose their absurdly loud vrooms on everyone else just because they want to? It's such a trivially stupid negative externality that has no reason to exist.
I used to live along Lawrence expressway in the Bay Area. At 45-50 mph, the noise that drown everything out was the tire noise. The Teslas were just as bad as any other modern ICE car.
Where the engine noise was noticeable was low speed intersections when cars would accelerate and the tire noise would be negligible.
After about 20mph, tire noise will overwhelm the noise made by even a (modern) ICE. Don’t get your hopes up. Granted, electric takes away the thing you attach a jackassly loud exhaust to, but tires are noisy.
Reducing the noise floor is likely to make it more disruptive to have the window open, because the intermittent outliers (trains, buses, motorcycles, trucks) will be even more prominent.
I live outside Muni/Caltrain. They're not great, noise-wise, but the motorcycles are 10000x worse. I get a number going by a day, and I just can't understand why they're allowed to be so absurdly loud.
Buses/trains are relatively quiet, outside of a few edge cases like tracks scraping or honking when someone's in their way - rare occurrences.
My dorm was a bus stop. Each time the bus came there were air brakes, a recording announcing the route and station, and the warning beeps for kneeling and wheelchair ramp extension. Fortunately it did not have a shelter, as many bus shelters in Chicago now beep continuously so that blind people can find them.
My first apartment was outside a level crossing frequented by Amtrak and Union Pacific. The federally required horn blasts - 2 long, 1 short, 1 long - overwhelm anything you might be doing or thinking about, resonate in your chest cavity. The building shakes, and the air becomes thick with diesel fumes and sediment kicked up from the railroad bed.
After an hour, I forget that the freeway is even there.
I'm on an intersection with caltrain, muni, and a freeway, but of course it can only be so informative. I'm not trying to say "Buses and trains aren't a problem" at all, I'm saying fuck motorcycles.
The Caltrain (and other trains but Caltrain is more frequent) going by San Mateo is brutal. Their horn is almost constantly on due to the many ground level intersections and they are ear drum busting loud (by regulation no less).
Areas where every level crossing is this good can be designated as quiet zones, but few municipalities want to spend the money on that. Train tracks are usually in industrial/commercial areas; homes near them are, shall we say, not centers of political power.
My intuition about this is that the deflection, intensity, and directionality of the noise from motorcycles impacts street level noise more than trains in a rail corridor. I believe that is why good street planning incorporates natural features that absorb and deflect noise, like greenery on street corners, for example.
I live next to a busy street with electric trolleybuses (essentially rubber wheeled city buses that use electrical power from overhead lines.) They're very quiet compared to the odd diesel-powered truck, but the tires on pavement still produce a noticeable amount of noise.
There have been discussions about adding back artificial noise, since a noiseless car would be extremely difficult to detect for people who don't have sight.
Also a fair amount of noise generated by cars is not the engine; for example, you have the sound of the tires rolling on the pavement.
In the US there are plenty of poorly maintained vehicles on the road emitting a lot of other nosies - squeaky belts, damaged or missing mufflers, rattling panels, worn brake rotors or pads.
Most states have very lax inspection requirements.
Even in my state, which supposedly is one of the strictest on inspections, it's surprisingly easy to have a dangerous failing car pass.
Living near a busy intersection you hear all sorts of weird mechanical failures as cars brake and accelerate from the stoplight.
While a highway with high speed traffic sounds like a loud whooshing sound, from tires on pavement and air displacement. Engine sounds are almost impossible to notice.
Intersection sounds like <35 mph, so you are agreeing with me.
Isn’t it also the case that a big heavy car with gigantic tires is louder than a lighter car with narrower tires? A Tesla Model X is pretty dang loud at 45 MPH, compared to something like a BMW i3 that weighs half as much and looks like it wears bicycle tires.
Absolutely. Basically the volume of sound emitted increases in proportion to the tyre size and speed, and also is affected by its tread pattern.
In short, the road noise from tyres is due to air being compressed by the tread and then released again. It's basically a constant rolling version of clapping your hands.
Modern formulations of tarmac are designed to settle with air channels (called voidage) to provide an exhaust for that air, significantly reducing the volume. If you want more information on a couple of types, look up stone-matrix asphalt or open-graded friction course. Concrete on the other hand is notoriously poor for sound reduction, because the surface is so much smoother.
As a rough rule of thumb, quietened surfaces come in at 6-9db lower than a comparable non-quietened surface.
ARFC is another kind, made of recycled rubber mixed as a secondary aggregate. It's commonly used as a quiet and long lasting surface in parts of the US, and has the advantage of being a good product for using up waste tyres. In the UK we have different compounds, which do similar things. The M4 between Swindon and Bristol is a particular treat to drive on acoustically.
Undersurface is potentially an issue too. For example, concrete surfaced in mono-aggregate based tarmac has a tendency to resonate and "sing". Concrete with undulations does the same, though for different reasons.
Not ATM. I've been thinking of writing a book on acoustics and perception of sound though for about 5 years, which is related to how I know about this sort of stuff. I've also built speakers in my spare time.
I've always been fascinated by sound and how people perceive it. I'm also a classical pianist and guitarist, amongst other things, which may explain it, or be caused by it. Who knows?
It's not something I thought other people would care to read about though, hence never doing it. Maybe time to re-evaluate that.
Small naturally aspirated gasoline engines are also quieter than turbodiesels. With some good noise dampening in the engine compartment and exhaust system some cars are surprisingly quiet even at low speeds. Also, some roads are louder than others (cobblestone being very loud regardless of speed).
It would actually be fine with current gasoline cars minus motorcycles and small handful of people who purposefully make their vehicles loud for... who knows what purpose.
Motorcycles as stock under EURO5 typically aren't that loud, it's the obnoxious after-market exhausts that make them so loud particularly with the baffles removed.
> but I’m hopeful that we’ll someday get to a point where (almost) all of the vehicles on our roads will be electric.
While we wait for that why can't architects/planners take soundproofing more seriously (if they've considered it at all) and actually make the walls and windows inside a building soundproof. It's not even outside noise, I lived in apartments where I could hear my adjacent neighbors.
The EPA has noise abatement regulations. Your city and state may also be involved. A lot of things are exempted usually though, such as trains, planes and automobiles.
When it comes to passenger cars, most noise is generated by tires hitting the road. Especially at higher speeds the engine noise doesn’t really contribute anything meaningful to the noise you hear. So electric cars won’t solve this problem.
EVs will require a mind change. I have a hybrid. I drive it in St Augustine FL, America’s oldest city. As such the roads in the historic district are narrow.
When I come to an intersection I have to be especially conscientious because pedestrians are use to engine noise bouncing down the road ahead of the car. People have walked out in front of me unaware of my existence. I normally mouth, “Surprise, motha fucka” or “I’m Batman” when that happens.
Yeah people will need to get aware of that. I'm European and drive a Renault Zoe. It plays some sort of "whoooooo" noise from under the bonnet/hood when you drive slower than 30 km (19 mi).
On one hand, I think it's dumb because why am I explicitly making noise? So I turned it off. But then I scared the living hell out of two shopping ladies when I unintentionally crept up behind them, and now I always leave it on.
Not much benefit from any kind of engine and noise when people walk or cycle with earphones. That is very usual view for me nowadays. Worse if they also stare at they phones too - blind and deaf at will.
I've said this before in comments but I just really have trouble understanding people who can walk--especially in cities--with earphones. I know some are less isolating than others--some like the pass through mode on the Airpod Pros. But I don't even really like earphones on a forest path much less a city street.
I guess it's somewhat a matter of what you're used to. I grew up pre-Walkman and have just never gotten into the habit of wearing earphones like that.
In the US, EVs and hybrids will be required (I'm unclear on the details from the articles I've seen though) to emit artificial noise under 18.6 mph by Sept 2020, and in the EU, under 15 mph by July 2021. [0] Hopefully that will help some, but I'm not excited for the first wave of noises. I'm betting a few are going to be really annoying.
I'm looking forward to it. I use hearing when coming up on intersections in my neighborhood and on a bicycle. The visibility is terrible. I'm never at risk of being run over, but it always shocks me pretty good to see a car coming towards the intersection without a sound. I can hear up to 19khz so I usually hear the batteries/motors, but not all cars make that sound.
I empathize with this viewpoint, but I can't understate how strongly I oppose this idea. Road noise is extremely unpleasant! If somehow the electric motor vehicle had been invented first instead of the ICE there is no way anybody would have proposed that we make them artificially louder... we can put other, much more effective traffic safety measures in place.
I too enjoy cycling and understand that there are serious safety problems involved with cars and bikes sharing the road and that and most of our cities have done a poor job of dealing with them. I don't think keeping around legacy noise pollution is the answer. It reminds me of this: https://xkcd.com/1172/
We have to stop treating noise as a mere annoyance or as something that "Karens" bitch about because of their priviledge.
It's polution, a health issue, something that ruins quality of life, and for people with certain health issues can be a chronic problem. It prevents people from sleeping, focusing, lowers productivity, make people "dumber", you name it.
In a lot of ways, the impact of noise can be similar to that of lead pipes. And we act like we can just tell people to deal with it, and that white noise machines and earplugs (hello ear infections!) are a solution (spoiler. I use both and it barely makes a dent in the noise sometimes).
Cyclists who ride regularly in traffic subconsciously use sound and to a lesser extent air pressure to detect and map the movements of larger vehicles. Unlike eyesight requires a head movement to detect anything not in a field of view in front of the cyclist, sound and air pressure changes can be detected from all directions. The noise of a car approaching from the rear gives an early indication that you are about to be overtaken, which reduces the potential to be surprised/frightened. Similarly the air pressure change can give an indication of the size of the vehicle - getting overtaken by a prime mover is different to a hatchback.
Increasingly, modern car drivers are enclosed in noise dampened, environmentally controlled environments with some sort of sound entertainment playing (music, podcast, talkback radio). So car drivers are less able to make good use of sound and other cues for detecting other traffic.
The lack of sound from hybrid cars, for example the Toyota Prius when accelerating in electric mode, has caught me by surprise while cycling. Not knowing you are about to be overtaken can be dangerous because there is an instinctive fight/flight response which can cause a sudden flinch or overreaction away from the surprise and you naturally turn your head to look at the perceived danger. As you are normally cycling on the edge of the roadway there is a higher potential to now accidentally ride over/into an obstruction (drainage grate, kerb, pothole) and come off your bike.
That or we can get to a point where we reduce cars in cities to a minimum. We'll probably still need car noise for the few that exist but the better solution in most ways is just to have way less cars.
You'd need a lot of exit ramps going up though, and it would be pretty tricky for emergency services to reach the places they need to go to. Personally I'm a big fan of reducing through traffic as much as possible and banning vehicles other than for the disabled and emergency services from city cores.
> We could have big houses, with windows that shutter in the summer mornings to keep out every bit of the too-early light of dawn, or shutter in the night to leave the stars absolutely untouched. We could have roofs that let in the sun.
