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I am no expert, but I would assume mainly due to cost. Heating a runway would be prohibitively expensive and the covering required to cover a runway would be prohibitively large.
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Because it's not a football pitch.
If it made financial sense and was possible, it would be done. BTW 27R is the equivalent of about 37 football pitches.
Probably very impractical given the size of a runway - not just to run, but implement.
Adequate equipment is the answer here, as it is in many countries that see more snow than we do in the UK. I know it isn't used a great deal here, but surely it's a relatively small investment work making?!
In fact much of the problem isn't to do with the runways in my experience. For example: I was stuck on a QR flight for over 6 hours this Feb on the day it started snowing - the 4th I recall. The reason why we were stuck all that time was down to the fact that they didn't seem to have enough de-icing trucks. 4 times we were de-iced, each time missing a takeoff slot because the de-icing trucks were always too late!
The heated runway could not be implemented. The Tarmac/asphalt required to handle 400 tonnes of metal being landed/ rolled over with the thrust of say (GE90 115B) 115,000 pounds, is pretty thick! The pipe work and energy required to heat through this large surface area would be enormous. But a nice idea.
When we finally get as cold as Scandinavia in the UK, we will start compacting the snow to land on it. It works rather well! Sadly snow in the uk just turns ( mostly) to slush on the runways in the uk. This causes huge problems with handling/ icing and grip. Hence total chaos. I agree that we simply do not have adequate de/anti-ice resources. Read cheap tickets = less money to invest in services
Some back of fag packet calculations, which I expect to be ripped apart by anyone who knows more about physics / snow :
According to the Telegraph, 2cm of snow on Heathrow's runways requires 5,300 tonnes of the stuff to be shifted. And that's ignoring the apron, which brings it up to 12,000 tonnes.
84 kJ x 12,000,000 kg = 1,008,000,000 kJ or 280,000 kWh. Even assuming a retail price of 16p / kWH that means it would cost £45,000 in energy to heat the runways and apron. Which isn't that much, considering.
So, to answer your question, if I've got my sums correct then there isn't much of a good reason. Two flaws in my maths I can see is that a) it assumes an efficient method of heating the snow, and b) it doesn't take account of heating the concrete itself.
Not worth the expense for all the time that snow/ice delays operations at LHR in a year. Fog probably causes more delays.....how about installing some giant air blowers?
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Some back of fag packet calculations, which I expect to be ripped apart by anyone who knows more about physics / snow :
According to the Telegraph, 2cm of snow on Heathrow's runways requires 5,300 tonnes of the stuff to be shifted. And that's ignoring the apron, which brings it up to 12,000 tonnes.
If it takes 419 kJ to raise 1kg of water from 0 degrees C to 100C, and if we assume that snow has a core temperature of about -20C, then we need about 84 kJ per kg to melt the snow or prevent it settling.
84 kJ x 12,000,000 kg = 1,008,000,000 kJ or 280,000 kWh. Even assuming a retail price of 16p / kWH that means it would cost £45,000 in energy to heat the runways and apron. Which isn't that much, considering.
So, to answer your question, if I've got my sums correct then there isn't much of a good reason. Two flaws in my maths I can see is that a) it assumes an efficient method of heating the snow, and b) it doesn't take account of heating the concrete itself.
I'd agree more or less with the above. The other problem faced is the surface temp of the runway. Those F1 fans amongst us will have seen the difference between air and surface temp. It can be quite significant! For a large dark coloured surface, such as a runway, it can be in the order of 10 degrees cooler after radiation cooling at night. So whilst the air temp might be 2 degrees after a clear night, the runway surface could be -8 degrees. This leads to icing issues and means an subsequent precipitation that falls freezes on impact. UK airports are quite good at preventing frost formation and clearing it, but when snow starts to fall first thing it really sticks. Grit/salt are NO GOs and would help to destroy the engines slowly. So it has to be mechanical and chemical methods that are used. The chemicals are good for removing frost or treating to preven frost, but large snow falls require brushes and ploughs. We simply do not have enougth of them.
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Flame throwers! Get pax to clear the runways. 10 Avios per square metre cleared
That's how it used to be done! A trench dug with side of he runway, filled with fuel and ignited. It works very well. Could bring a new meaning to landing in HEL if installed up there. :-)
84 kJ x 12,000,000 kg = 1,008,000,000 kJ or 280,000 kWh. Even assuming a retail price of 16p / kWH that means it would cost £45,000 in energy to heat the runways and apron.
Hmm. I think you left out the bit about heating up 50cm of tarmac first before you start heating up the snow. I think that might add a bit to your calculations.
