I also seem to recall seeing a plan - clearly never adopted - of runways at Heathrow which were (about 6?) as tangents to a sort of circular central taxiway, so each of the 3 directions had 2 runways, one starting, and one finishing at the central circle.
Very easy to draw on a beer mat, rather more difficult to describe - as you can see from the above!
Is this just a senior moment of "remembering with clarity something that never happened!", or does anyone else recall something similar .......