Winter operations
of around 60,000 flights across all 50 US states, costing the industry $3bn. Unsurprisingly, local officials don’t sit impassively as the storms roll in. As Dr Matthew Brynick explains, every airport has a “unique approach” to deal with snow and ice, and Des Moines is no different. “Vehicle-mounted snow blowers, brushes, and ploughs are common,” says Brynick, a civil engineer at the FAA William J Hughes Technical Center in New Jersey. “Chemicals, sand, snow melting and treatment facilities, and snow storage are utilised when appropriate.” All this is clearly supported by the statistics. Des Moines International has around ten snow ploughs, each costing $900,000, while airports regularly spend $20,000 on the chemicals needed for a standard de-icing session. Yet though these methods are tried and tested, they’re also far from perfect. Snow ploughs might weigh 50,000lb when loaded, but even expensive models are often painfully inept. In the worst squalls, they have to be deployed to the runway every 15 minutes, leaving precious little time for the aircraft themselves. De-icing chemicals are similarly inefficient. Halil Ceylan, a professor at Iowa State University, describes visiting Minneapolis-Saint Paul International Airport and seeing “85 workers sitting around the clock” in specialised barracks, complete with sleeping quarters and a canteen. Their only job? To decontaminate polluted snow. On that point, de-icing can cause huge environmental problems when left untreated, killing fish and sparking toxic algae blooms. According to an estimate by the Environmental Protection Agency (EPA), the US’s large hub airports discharge over one million tonnes of ammonia each year. To put that into perspective, drinking water in the US normally contains just 0.25mg of the compound per litre. Nor are these hypothetical problems. At New York’s JFK, for instance, de-icing runoff flowed into a nearby nature reserve as recently as 2009.
Seeing green
Ames is not necessarily the place you’d expect to find a solution to these deep global troubles. A genteel college town of 66,000, it wallows amiably in Iowa’s postcard-flat heartland. Des Moines is 40 miles to the south, and the local municipal airport typically hosts just one commercial flight a day. Yet it was here, during yet another nasty winter, that Halil Ceylan was prodded into action. He noticed stories in the local paper, describing how many of Ames’s 33,000 students – some presumably his own – would slip and injure themselves on icy pavements, often near crucial exams. But what if things could change? “I saw statements saying that ‘I don’t have time for this,’” Ceylan remembers. “And they have every reason to say that.”
Future Airport /
www.futureairport.com
To be fair, Ceylan didn’t end up stumbling into something completely new. Airports worldwide have experimented with heated pavements for years, using special types of asphalt to melt snow and ice before the snow ploughs or de-icing chemicals are needed. Yet as Brynick explains, these older variants come with a shopping list of problems. Many hydronic heated systems, for instance, are piped full of antifreeze. Naturally, any leak can be environmentally disastrous. So-called resistive wire heated pavements, for their part, avoid that particular flaw. But because they rely on a series of circuits, a single broken cable can ruin an entire section of concrete. As Brynick puts it, “Identifying and rehabilitating this discontinuity when it occurs can be costly and destructive.” Electrically conductive concrete heated pavements, on the other hand, are far simpler. Developed by Ceylan and Brynick, together with partners at the so-called ‘PEGASAS’ programme, they blend carbon fibres and other electrically conductive materials directly into raw concrete. This uncomplicated approach reduces the risk of things going wrong. Nor do the advantages of the new technology end there. Though other researchers have experimented with similar systems, they’ve tended to use steel shavings rather than carbon fibre or graphite. Because of the relative conductive powers of the materials involved, steel can sometimes account for up to 20% of the total mixture, making it far harder to make. Ceylan’s recipe, for its part, only needs a sprinkling of carbon fibre – about 1%. In the same vein, this new technique only fills the top two or three inches of asphalt with conductive materials. Anything below is just regular concrete, saving money and heating those crucial top inches much faster. Clearly, the proof of any pudding is in the eating.
Yet here too, the latest electrically conductive technology is proving its worth. Trialed by Des Moines International from 2018, the pavements have stayed satisfyingly clear of ice, without ever needing to spray them with antifreeze or turning on a snow
Des Moines International is the first US airport to trial electrically conductive heated pavements.
$3bn Business Insider 33
The cost to the industry from the 60,000 flights cancelled due to winter weather each year in the US.
FAA
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