That is a good point. In the UK when I was last there they needed all sorts of tricks to get people to slow down on roundabouts on A roads or just after a motor

That is a good point. In the UK when I was last there they needed all sorts of tricks to get people to slow down on roundabouts on A roads or just after a motorway end, going from say 70mph to zero. You might have a curve leading up to the round about plus roundabout signs, plus give way signs, plus 300, 200, 100 yard markers, plus painted lines on the road that get closer together as you approach, and finally the <<<<< sign on the roundabout itself.