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RoyHudd
20th Jul 2007, 07:59
Can anyone advise whether removal of such is expensive and/or time consuming? What is the method used for cleaning? (Chemicals, non-ecological?)
I expect there must be a good reason why so many r/w's are covered in the stuff, but am curious. A lot of fields, from Dom. Rep to Greek islands, not excluding our own country, have filthy r/w ends and turning facilities, which can be quite slippery when recently soaked.
As an A320/330 driver, I find myself concerned with the Congonhas tragedy, having jump-seated in and out of that tight field on a number of occasions. (On Electras...much nicer). This has prompted my question, although I accept that many other factors than aquaplaning may have come into play.

Musket90
20th Jul 2007, 08:15
On grooved asphalt runways at LON airports where rubber build up reduces friction levels I believe high pressure water is the method used. Normally carried out a couple of times a year at the TDZ areas. Chemicals have been trialled but the water method is I believe still the most effective.

It is fairly costly because of specialist equipment needed but for a couple of times a year to maintain good friction levels and a safe running surface then cost is not an issue.

john_tullamarine
20th Jul 2007, 09:24
I've sent a signal off to OverRun, our resident airports engineering expert ... no doubt he will offer comment in due course ...

OverRun
21st Jul 2007, 09:36
Both chemical methods and ultra high-pressure water can be used. The chemicals (at least the ones that work well) are ecologically unfriendly. The high pressure water is specialist equipment - not just the fire truck's high pressure hoses. Slow process. Not especially cheap or expensive, but about $US3 per square metre (say $50,000 for an average runway for the two touchdown areas + mobilisation of $10,000-$20,000).

The rate of rubber buildup is proportional to the number of landings as one would imagine, and there are various rules (especially FAA) about the frequency that the runway should be inspected. Removal periods can vary from once a year to more than once a month. At over 210 landings per day, the friction should be tested weekly. Where I am today (YBRM) which is pleasantly quiet, they wait for the annual wet season to wash the rubber off.

Friction is best assessment method. A runway that is white (such as concrete or a bitumen/asphalt with a white coloured aggregate) looks much worse than a black runway with the same friction degradation.

Why would you leave a runway uncleaned beyond any reasonable limit - lazy? incompetent? too hard to arrange to fix? on an island and the high pressure truck has to come by ferry and it won't come for another 2 months then the tourist season is over anyway so why bother and now it's lunchtime so I am off duty?