If airport runways are clear, why not streets?

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Have you ever marveled at how airports can keep a tarmac clear in a snowstorm – a rare oasis of bare pavement surrounded by snow-covered landscape?

The Star Tribune asks: Why can't we do that with streets?

Short answer: We could, but it would be enormously expensive.

The Minneapolis-St. Paul International Airport uses a potassium acetate that costs roughly $15,000 for each application, and a Minneapolis streets official estimates it would cost about $455,000 to treat 1,000 miles of city streets (the city has about 1,100 miles total) with the chemical, the Star Tribune reports. Good old rock salt used on roads is far cheaper – about 3 percent of the equivalent cost of what they use at MSP, the newspaper reports.

Another factor of course is that airports deploy a lot of costly manpower to attack the snowy runways – small armies of crews armed with plows, sweepers and blowers.

Also, at big airports, those crews can divert traffic to other runways as they clear one, the Star Tribune reports. Road crews, by comparison, are fighting snow-compressing, rut-making traffic as they try to clear hundreds of miles of roadways. MSP has only about 9 miles of runway to worry about. (Road crews also battle parkers; St. Paul this week ticketed 2,000 car owners who ignored a new one-side parking rule.)

And certainly, unlike at the airport, there are lots of roads that don't get plowed until after the snow stops falling.

The Star Tribune also examines some differences in the "brines" that various Midwestern road crews use. It notes that the Minnesota Department of Transportation has used soybean oil and corn-based this winter. Crews around Wisconsin used a cheese-based brine, made with the byproduct of cheese-making. Other areas have experimented with beets and potato brines, among other mixtures.

Of course, airports can't always keep the tarmacs clear; sometimes big snowstorms cancel flights, close airports and strand passengers. Pilot Patrick Smith writes here about how it is that tarmac logistics can quickly deteriorate in a big snowstorm.

Time magazine this month in a cover story went inside the strange world of airline cancellations, examining the esoteric details of how those decisions get made.

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