Why is a runway so long?

Answer 1

The length of a runway is based on the takeoff and landing needs of the aircraft that will use it. Airports that service large commercial jetliners will typically have much longer runways than airports that only service small private jets or propeller driven planes. That is because smaller aircraft typically require less distance to takeoff and land than larger, heavier aircraft.

The length of any given runway will also take into consideration factors such as potential bad weather such as wind, rain, ice, and snow. Runways often have a built-in margin of safety to allow for circumstances such as a pilot over shooting the landing area, engine failure, or mechanical problems such as blown tires or faulty landing gear.