Hacker News Reader

Comment by tootie | Hacker News Reader

I live near one of the busiest highways in the country and it's just sorta background noise for the neighborhood. I'm not sure people realize not only how much exhaust is spewing out of that road, but also the noise. The volume level of major cities is going to decrease dramatically.

View on HN

At highway speeds, the sound of a modern cars (ICE or otherwise) is mostly tire noise. Electric cars are much quieter at slower speeds, when tire noise is minimal.

Can we get electric tires then? (Or figure out how to fix tire noise)

Is not the tires 100%. The asphalt or the road composition and degradation plays a role.

We have a small highway section which was newly done (somewhere in Germany). They seemd to use a different composition and construction method, man, this road is soo silent, even at >200km/h.

On highway 85 near Cupertino a few years ago they did something called “microgrooving” and it made a huge difference in tire noise, even inside your car. It’s dramatically quieter when you suddenly hit that section.

What also helps immensely both in noise and road wear is that no trucks are allowed on 85.

They also designed in sound-absorbing walls.

I couldn't find reference to this technique could you go into more detail please ?

Here’s a little detail - https://www.mercurynews.com/2015/03/02/roadshow-groovy-highw...

Smaller tires are generally quieter, go for the 16" rims instead of the 18". You'll also see better mileage usually.

Tire thickness is another factor, get the lowest speed rating tires you can if you don't need to go faster than 112 mph/180 km/h, the recommended speed limit of the common rating 'S'.

Of course you should avoid studded tires if you're optimizing for noise, but also All-terrain tires are going to be loud.

1. Why would smaller tires be any quieter?

2. Smaller rims do not mean smaller tires. On a given car model, the outside diameter of the tire will be essentially fixed. If they have multiple wheel diameters, the tire sidewall height will change to accommodate the wheel diameter. Technically smaller-diameter rims actually mean larger tires.

You're right about the sizing. I didn't separate my wording of tire and rims enough.

I will defer to a blurb I just Googled: http://elevatingsound.com/your-guide-to-getting-quiet-tires-...

It's quite noticeable when going from "new" asphalt to old or vice versa at freeway speeds. Air resistance adds quite a bit of sound as well, the faster you go.

Where I am (Manhattan) its truck noise. Trucks are the absolute worst in terms of noise pollution and emissions. Most modern cars/taxis around here are some sort of hybrid which shuts the engine when stopped, yet trucks are still in the stone age. And to top it off, there's really no political willpower to reign in bad trucker behavior.

Modern ICE cars are shut off at stops. No battery required.

Not to be pedantic, but modern ICE cars still have batteries...

They aren't hybrids with their attendant motive power battery.

I noticed certain builds of the Chevrolet Silverado 1500 offer an electric motor assist that also includes idle engine shutoff. We can only hope that is becomes a standard feature, electric motors in traffic jams would be wonderful.

http://gmauthority.com/blog/gm/gm-engines/l8b/

100%. A garbage truck and a tiny pothole are magnitudes louder than any consumer vehicle. Repaving the roads would have a much larger effect on noise than replacing every ICE vehicle with a tesla.

here in Paris the 150cc scooters are much worse. Very high RPM and incredible noise

e.g. late night pizza delivery wakes up the neighbourhood

Good news, electric scooters are a thing, and they're very quiet.

I wouldn't say they're a thing yet; there are some nice 'luxury' electric scooters, and there are cheap lead-acid scooters, but not too much in between yet.

I'd love an affordable, reasonably well-constructed LiIon scooter, but it's not there. Definitely coming, but not here yet.

Seems to be coming a few now. At least locally there's several li-ion options in the 2k-3k USD range, most with 30-40km range. Quite affordable here for most.

Don't forget the diesel soot. Leave your window open for the day and come back to suit covering everything.

I'm not in public policy or anything, but it's kind of baffling that no one is targeting fleet vehicles as the obvious first target for cleaning up. Trying to convince consumers of the value of electric vehicles is hard. Trying to convince a guy who is paying maintenance and fuel costs for 4,000 vehicles should be a piece of cake. Especially if you just force them through legislation. Mayor De Blasio could mandate all livery vehicles be electric by 2030 and that's an instant captive market of over 100K vehicles.

I dunno about the US but everyone I known in Europe that lives in a city or close to a highway is looking forward to the electric future. This has become a recurring topic in dinner conversations as more and more people have first hand experience with electric vehicles now.

Imagine how quiet a city like Paris, Rome or Berlin could be if all vehicles were electric?

I can't wait for this future to arrive and the fact that I will enjoy it a decade earlier -- at least -- I'll owe to Musk/Tesla. More power to them.

I'm sad to say that except for trucks the majority of noises from highways these days is from tires. I read a rather long article, in the Atlantic I believe. Apparently car weights have been on the rise for 70 years and on top of that the trend for the same weight car is for wider tires. The increasing noise has been a constant pain for highway planners because population density is increasing, traffic is increasing, and noise per car is increasing. Technology for noise abatement is improving, but expensive.

Given that Tesla cars and anything with similar range is likely to be another 1000 pounds heavier than cars in it's class, the prospect for quieter cars is poor.

Stand on a sidewalk sometime and listen. At constant speed or slowing down electric cars vs normal cars are pretty similar, but be careful to compare cars of similar vintage. This is part of the way I think legislation that add noise to electric cars for safety is misguided. Compare a 2018 BMW, Lexus, Acura, and MB vs a Tesla. Any of them could easily hit you before you easily hear them.

After living next to commuter rail and bus stops, I’m amazed that private car noise is even a complaint. A train horn is felt in your chest. Air brakes and audible announcements are much more noticeable because they’re intermittent where tire noise is a constant hum easily tuned out.

I moved right next to a Railroad crossing just about the time they started experimenting with a no horn crossing. Every now and then I still wake up to feel the whole room rocking from a fast train going by but it's still wonderfully quiet.

https://helenair.com/news/crime-and-courts/helena-s-railroad...

Highway noise is mostly tire and wind noise, aside from the occasional loud engine. EVs will certainly reduce city street noise, but I'd bet highways will still be pretty loud.

Unfortunately tire noise contributes about 50% of the volume.

Tire noise has a much different "sonic signature" compared to exhaust noise and ICE noise, it is much closer to "white" noise and has not as much rumble. I'm not saying it's necessarily any better, but maybe it's going to be less annoying.

Maybe on the highway, but I would imagine that's not the case in major cities where cars are generally moving < 30 MPH.

Reply on news.ycombinator.com