GP was most likely thinking not of large roundabouts that take the place of major intersections, but the smaller traffic-calming type where the center can be as

GP was most likely thinking not of large roundabouts that take the place of major intersections, but the smaller traffic-calming type where the center can be as minimal as a 3 foot wide concrete block. They can be fit into pretty much any intersection because their purpose is not to change the path so much as to, frankly, eat up whatever extra space is available, which forces cars to slow around them.