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Why Do Airport Runways Cost So Much To Build?

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This question originally appeared on Quora.

Answer by Tom Farrier, Aviation Safety Expert

This is a link to a U.S. Federal Aviation Administration publication that describes the amazing level of complexity associated with construction of a runway:

It's a daunting 580+ pages of minutiae, but that's kind of the point. Building a runway is even more complex than building a major highway/motorway, which has similar demands in terms of the need for an extremely well engineered surface, high levels of quality control in the materials used, and superior drainage. Runways, once constructed, must be capable of being kept in good repair for many years, including periodic removal of accumulated rubber and other foreign matter and at least one or two major resurfacings. However, it also is understood that runways can in effect "wear out" over time, and may require complete removal and replacement with a new multilayered runway in its place.

The most distinguishing characteristic of modern runways, however, is the need for them to accept increasingly heavy aircraft slamming down upon them and taxiing on and off at many points along their length. The Airbus A380 is certificated to take off at a weight of over 1 million pounds. Aircraft weighing over well over 100,000 pounds at landing are the norm rather than the exception at major international airports. To handle such incredible loads on a regular basis -- not to mention temperature extremes in many locations that can easily lead to "spalling" (surface erosion) if not accounted for in the materials used -- runways must be built with care and precision.

A notorious instance of lowest-bidder preference (or penny-wise, pound-foolish thinking) some years ago resulted in a fighter base needing virtually an entire runway torn out and replaced when its rebuilt runway started showing serious damage almost immediately upon its re-opening. The winning contractor was later determined to have extensive concrete pouring expertise ... unfortunately, said experience was for the most part confined to laying down home patios. Oops.

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