3 ms·
That doesn't make sense to me either. Take a busy German highway (as I don't know the average load on US ones), easily 100k cars per day. There are parts of hig
by saiya-jin 7y ago
That doesn't make sense to me either. Take a busy German highway (as I don't know the average load on US ones), easily 100k cars per day. There are parts of highways which don't get replaced for 20 years easily. Plus apart from tiny fraction of north europe (and maybe Canada?), nobody ever uses studs.
Back of the envelope math tells me 1 km of highway would lose some 730 tonnes of asphalt, per year (so 14,600 tonnes in 20 years). If we talk about normal car wear, this simply isn't happening on those unkempt roads. It would leave huge lanes of deeper surface where asphalt is lacking. There isn't visible wear on lanes that are used mostly by cars like that. Roads have mostly potholes.
What happens on those roads is, sticky asphalt is worn away (but not at the mentioned rate), and what remains are stones which basically don't wear, and tires touch only that. At least highway surface I saw was like that.
What damages roads greatly are trucks, especially overloaded ones (say limit is 15 tonnes, they take 22 tonnes and hope to not be checked... welcome to east european mentality).
- loeg 7y agoPeople use studded tires the US, too.
- 9HZZRfNlpR 7y agoAnd Eastern Europe, colder parts of Russia etc.
- Causality1 7y agoA rough way to think about road wear is the weight over one axle to the fourth power times the number of axles.
- na85 7y agoThat gives you a quantity of force^4. How does that translate to road wear?
- cheerlessbog 7y agoEmpirical studies apparently find road wear matches a power law. Although it seems the exponent varies. Here's a survey https://www.nzta.govt.nz/assets/resources/603/RR-603-The-relationship-between-vehicle-axle-loadings-and-pavement-wear2.pdf https://www.nzta.govt.nz/assets/resources/603/RR-603-The-rel...
- na85 7y agoThat's for rutting damage, which doesn't necessarily translate linearly to particulate formation/flaking.
- xenonite 7y agoIndeed, trucks greatly damage roads. For example a 2 tonnes car has 2 axles, hence a=1 tonne per axle. A 20 tonnes truck with 2 axles has b=10 tonnes per axle. Then, the road damage per axle increases by a power of four [1], i.e., by (b/a)^4=10000. [1] https://de.wikipedia.org/wiki/Vierte-Potenz-Gesetz https://de.wikipedia.org/wiki/Vierte-Potenz-Gesetz