If you think that everything you can think of has already been invented, you are wrong. Recently BBC News posted a film [1] presenting the idea of circular runways. The Endless Runway is a project run by the NLR in the Netherlands. The principle of The Endless Runway is that aircraft take-off and land on a circular runway. The circular runway will allow aircraft to take-off in any direction and land in any direction, making it possible for the aircraft to always land and take-off in the most desirable direction with respect to the wind: headwind. The possibility for aircraft to land and take-off without experiencing crosswind at all times is not the only advantage to the concept of circular runways. In low wind conditions, it would be possible to shorten the landing and take-off intervals. In low wind conditions an arbitrary direction of landing or take-off can be chosen, enabling the operation of multiple aircraft simultaneously on the runway. In addition to this, the possibility of landing and taking-off in any direction gives the freedom of deciding where to fly and where not to fly in the airport’s environment.
The Endless Runway [2]
The idea would be for the runways to lie around the airport and the runway would be constructed at an angle. The circular runway is equivalent in length to three straight runways, and it has been calculated that it can handle the work of four straight runways. Although the idea of circular runways has been circling around for a while now, up until now it has never been built. However, no-one knows what the future holds.
[1] http://www.bbc.com/news/magazine-39284294
[2] http://www.endlessrunway-project.eu/project/index.php