What is the saturation level of a round about?

Question

particulary Urban roads road-about intersections

Answer 1

If you are talking about round intersections where roads meet the circle (ring) instead of traffic lights then the maximum number of vehicles (total in both directions) going through the intersection is the number of vehicles entering one entrance times the number of entrances. This is the case where every vehicle exits the first road to the right of his entrance road. In all other cases there is a conflict (one vehicle must wait for the other) which slows the pass through (throughput).