Making Quieter Highways

An anonymous reader writes "Researchers at Purdue are investigating ways to make life for those who live near major highways more quiet. They have found that most of the noise is literally where the rubber hits the road, not engine noise or even passing winds. The team has come up with a new form of pavement that is in testing in Arizona and will soon be installed in California. The pavement is simply asphalt with some mixed in rubber."

Comments

They've only just figured this out?

[gazbo]

On the A31 near where I used to live there is a stretch that is done in a noticeably darker (and smoother) tarmac. I think it was done specifically for noise reduction, and when driving over it you can really tell - it's a tremendous difference. Like you know if you're in a room with a washing machine and it finishes, and suddenly you're aware of how quiet everything is? Same sort of effect.

Now I'm not saying it's the same stuff, but is it really a new finding that it is the tire/road contact that's noisy when this was done at least 6 years ago?

Re:They've only just figured this out?

[jilles]

Yep, in the Netherlands this kind of thing is long past the testing stage. My country is pretty densely populated and has quite a few highly congested highways. We have standards for sound levels which have to be met. This has created a financial incentive for road constructioners to research solutions to reducing the noise and meeting those standards.

A combination of sound deflecting shields in populated areas and better road surfaces is pretty much standard for roads nowadays here. My parents live about 1km from a very busy highway and while you can hear some noise in the background if it is really quiet (like at night) it can barely be heard.

Coefficient of friction

[n1ywb]

From http://www.hronline.com/forums/ohs/0109/msg00073.h tml

The coefficient of kinetic friction of rubber on rubber is listed in this
source as Natural rubber, vulcanised at 100m/min on rubber flooring or
rubber tread vulcanisate, clean, - 1.16. That's pretty high!

That IS pretty DAMN high! The coefficient of friction of rubber on dry asphalt is around 0.6 or 0.7, which is already considered to be pretty high. So logically, adding rubber to asphalt would probably improve the coefficient of friction between the tires and the road, hence decreasing stopping distance and improving cornering.

Physics is the study of everything.

Whoosh!

[tickticker]

I live near the sections of highway where they have laid this stuff, and it's like pulling a nail out of your head when you hit it. The constant hum of the road is much more intrusive then you can imagine. It's alot like turning off the range hood fan after it's been on for a couple hours and the hum has invaded your bones. All you hear is the wind around the vehicle.

I look forward to hitting the stuff, and they are supposed to be repaving a 21 mile portion of a highway thats not even 3 years old yet. (The highway system in Phoenix is still pretty new and growing)

I don't need a sig

Still recyclable?

[Xunker]

One thing the article doesn't touch on is reusability. One thing that the paving industry likes to pride itself on is that asphalt is almost totally recyclable. However, to my understanding, dense rubbers (such as car tires) aren't reuasable in that way, they can't be melted down and reused with reliability. Would the addition of the rubber have a problem with the recasting of the asphalt? With the amount of repaving that happens every year, what sort of effect will this have on the waste output of a repaving operation?

Re:liars and thieves

[passthecrackpipe]

If you would have looked at the content of my post, you would have seen that it concerns a mixture of asphalt as well as concrete. ZOAB technology is now about 15 years old in backwards Europe, so we have gone ahead and recently invented a 2 layer mixture, where the top layer has a higher density then the bottom layer. this greatly reduces sound pollution, and has a much lower requirement for maintenance. It is also more environmentally friendly. To top it off, pun intended, there is a topcoat of a mixture of different polymers that act as a filter, letting water through, but at the same time keeping freezing temperatures out, doing away with the "black ice" phenomena - you know, a thin sheet of ice that is invisible, until you see the big pile-up ahead of you? It also reduces sound pollution more, but is more expensive.

I checked with a mate of mine that actually works on this stuff, and latest I heard, some USians are coming to see how it is done. We stopped playing with rubber about 25 years ago. Soon, you will learn that GSM makes for better cell networks, PAL is the better display standard, Open source is the way to go for software development and deployment (Europe leads the way in terms of OSS deployment, in terms of percentage as well as hard numbers.) and various other "Mysterious Happenings From The Future"

Blind anti-americanism, just because I think the US is silly for not adopting existing, tried and tested technologies - from their allies, of all things - rather then re-inventing the wheel? A troll, I say. Anyway, next time you need a "coalition partner" to give your oil-grabbing excercise a veneer of legitimacy, it will probably be an EU country you will be turning to. Eurotrash Indeed....