Compared with other types of intersections, a roundabout has some benefits. Firstly, It improves the capacity in some extent by reducing the conflict points and improving the travel safety. Secondly, a roundabout without signalized control has high efficiency because vehicles can pass the intersection with a regular speed, avoiding vehicles' delay caused by a common signalized intersection. But the interweaving section influences the capacity of unsignalized roundabout. Regardless of the number of lanes in each approach, traffic streams have to interweave on the round lanes. When the length of the interweaving section is shorter than two times of the allowed minimum length, the capacity of unsignalized roundabout is equal to capacity of a single lane. When the length of interweaving section is longer than two times of the allowed minimum length, the capacity will increase, but not evidently. So the capacity of unsignalized roundabout is limited. When there are bicycles and pedestrians, the problem will be more serious. In this paper, the new traffic control and management system for roundabouts is put forward to solve the aforementioned problems of roundabout.
Abstract