Why the difference in roadmaking?

[mat777]

I've just been watching an episode of "how it's made" talking about the construction of the Dan Ryan expressway in Chicago. I was struck by the complexity of it. Over her, a motorway is laid as good layer of asphalt on top of hardcore bedding. But over there, they laid the hardcore, then the asphalt, then they lay a grid of steel mesh that sits about a foot off the top of the tarmac. Over this they pour a foot and a half thick cake of concrete, then score that with a big rake so it isnt completely lethal in the rain.
Why all the extra effort? Not only is asphalt apparently plenty tough enough for our jam packed motorways, but it is also way more grippy than even scored concrete. Oh, and as the few concrete motorway stretches over here prove, asphalt is also nowhere near as bloody noisy!

[parapaul]

For definite, concrete is harder wearing, so I suspect it's a cost-based decision.

But you're right, concrete roads are horribly noisy, the A50 from Stoke to Uttoxeter in Staffordshire is concrete for several miles, it's a nightmare.

[jon-]

Slightly off topic, but I've always wondered why american toilets often employ an efficient "empty then refill" system for the bowl, when our toilets just attempt to stir and churn everything.

[h0b0]

It could be due to the extreme temperature changes some parts of the US have. Where I live we have -10 to 120 degrees Fahrenheit. We also have to plow 6ft of snow which causes havoc with the roads.

[jimmyjimjim]

Cost for a large part; there was an article in time magazine many, many years ago, that compared the anatomy of a US road with a european road. For the comparison, there were about 5 or 7 different layers, and in each case, the layers in the US roads were about half the thickness of those in the european roads. Obviously this made them substantially cheaper. Which, as they tend to be substantially longer, makes sense.

For the most part(inner cities excluded)they also have less traffic, so the life worked out as being similar.

Concrete surface? As above, asphalt tends to get screwed over by the greater temperature differential - I've seen about -25c to +40c odd here in Colorado, and the expansion tends to screw them up quite quickly. Add in the regular snow plowing in the winter, and they get worn out/ripped up incredibly quickly.

Concrete lasts longer in those circumstances, and is cheaper to repair.

Then again, I was driving from NJ to OH one time and came accross the road sign "The next 5 miles of the Pennsylvania turnpike is the first fully resurfaced section of the turnpike", clearly proud of this.
Unfortunately, about 50 yards after the sign, the road dropped 4" where they'd scraped the surface off and were about to start relaying it - clearly it hadn't gone as well as it should have.

[jimmyjimjim]

One thing that I find interesting is when they do repairs to concrete roads - they saw the offending section out in order to have a clean demarcation line, so as you pass by it, you can see the foot of so of concrete that they need to pour to finish the repair.

[Gixer]

Maybe so their roads last more than 5 mins. Our roads are ste quality compared to most in Europe. They rut, pot hole and fall apart in in time mainly because the tarmac is so thin. Check out how thick they lay an autobahn. There is a section of the A12 they grooved, it works and is much quieter

[Gixer]

jimmyjimjim said:

Cost for a large part; there was an article in time magazine many, many years ago, that compared the anatomy of a US road with a european road. For the comparison, there were about 5 or 7 different layers, and in each case, the layers in the US roads were about half the thickness of those in the european roads. Obviously this made them substantially cheaper. Which, as they tend to be substantially longer, makes sense.

For the most part(inner cities excluded)they also have less traffic, so the life worked out as being similar.

Concrete surface? As above, asphalt tends to get screwed over by the greater temperature differential - I've seen about -25c to +40c odd here in Colorado, and the expansion tends to screw them up quite quickly. Add in the regular snow plowing in the winter, and they get worn out/ripped up incredibly quickly.

Concrete lasts longer in those circumstances, and is cheaper to repair.

Then again, I was driving from NJ to OH one time and came accross the road sign "The next 5 miles of the Pennsylvania turnpike is the first fully resurfaced section of the turnpike", clearly proud of this.
Unfortunately, about 50 yards after the sign, the road dropped 4" where they'd scraped the surface off and were about to start relaying it - clearly it hadn't gone as well as it should have.

What European roads though?

French? German? Ours? I suspect not ours