Space to make a dual carriageway interchange

Since Highways England say we can't be trusted with maps, let's make up a few of our own.

The average dual carriageway interchange takes 1km in every direction, to allow cars 0.5km to slow down on slip roads. Here's a 1km circle around the Southerham Roundabout, and another round the Cophall Roundabout.  Both new interchanges will require 'three-lane-flares'. They'll look nice in the landscape, won't they ?