Airport runways (up to 3.5 kilometers long) have reinforced concrete foundations, deepest (up to 1.5 meters) in the touchdown zone to handle the repeated pounding of hundreds of thousands of landings every year by airplanes weighing up to about 380 tons (the Airbus 380). For example, Canada’s longest runway (4.27 kilometers, in Calgary) required more than 85,000 cubic meters of concrete and 16,000 tons of reinforcing steel.[95]
