Is Our Infrastructure Ready For Rising Temperatures? 416
Hugh Pickens writes "Megan Garber writes that last weekend, a US Airways flight taxiing for takeoff from Washington's Reagan National Airport got stuck on the tarmac for three hours because the tarmac had softened from the heat, and the plane had created — and then sunk into — a groove from which it couldn't, at first, be removed. So what makes an asphalt tarmac, the foundation of our mighty air network, turn to sponge? The answer is that our most common airport surface might not be fully suited to its new, excessively heated environment. One of asphalt's main selling points is precisely the fact that, because of its pitchy components, it's not quite solid: It's 'viscoelastic,' which makes it an ideal surface for the airport environment. As a solid, asphalt is sturdy; as a substance that can be made from — and transitioned back to — liquid, it's relatively easy to work with. And, crucially, it makes for runway repair work that is relatively efficient. But those selling points can also be asphalt's Achilles heel. Viscoelasticity means that the asphalt is always capable of liquefying. The problem, for National Airport's tarmac and the passengers who were stuck on it, was that this weekend's 100+-degree temperatures were a little less room temperature-like than they'd normally be, making the asphalt a little less solid that it would normally be. 'As ironic and as funny as the imgur seen round the world is, it may also be a hint at what's in store for us in a future of weirding weather. An aircraft sinking augurs the new challenges we'll face as temperatures keep rising.'"
Big rains - bigger culverts (Score:4, Interesting)
Metling permafrost in Colo. closed major highway (Score:5, Interesting)
Yesterday, CDOT closed [thedenverchannel.com] US-24, about the fourth most important highway in Colorado, due to ice 100 ft. down that melted for the first time (since a railroad tunnel was constructed a century ago) and created a sinkhole.
Re:Any mix for -18 to 38? (Score:5, Interesting)
Here in Chicago, we have a bigger swing than that by about 15 deg F. We've gone from less than -10 deg to 105 deg.
I swear, sometimes on the same day. Two weeks ago, we had very nearly a 50 degree swing in the course of 30 hours.
Last week, when we were over 100 all week long, there were pavement buckles all over the expressways. Thing is, we can make infrastructure that will last, but it means making it a priority higher than building an embassy in Iraq bigger than the Vatican.
Re:Nope. (Score:4, Interesting)
Yep. It is also why (in temperate regions at least - ie no real freezing) resealing work is ideally always done at the hottest time of the year.
There's an optimal viscosity for laying the stuff. So by sealing in summer they can then use a mix with the highest possible melting temp to hopefully avoid these sticky summer situations. Sealing roads etc when its colder requires a runnier mix, which then doesn't handle summers quite as well.
Of course places with a very wide seasonal temperature range make this much more challenging.
Comment removed (Score:5, Interesting)
Re:News to us in Texas (Score:5, Interesting)
Do you think the air in Phoenix (1200 feet) is ever at thin as the air in Denver (5280 feet)? Just by eyeballing it appears the density altitude [wikipedia.org] in Phoenix at 115 F is about 4,000 feet.
Re:Nothing new (Score:4, Interesting)
Lots of bus stops where buses are expected to sit for a while are paved with concrete because of this problem. When it's really hot out, buses sink into asphalt.
I think the actual reason for the concrete is that the frequent stops by heavy vehicles "pull" the blacktop like taffy, making a wavy spot on the road.
You get the same effect at stop lights on highways/boulevards that carry a lot of heavy vehicles.
Re:News to us in Texas (Score:4, Interesting)
Probably not, but I bet the Denver airport runways are longer than Phoenix's airport runways to compensate for the reduced amount of lift.