Research On Integrated Optimization Of Temporal And Spatial Resources For Signalized Roundabouts

Inappropriate allocation of temporal and spatial resource leads to decline of transportation effiency for roundabouts. The paper regards the signalized roundabout as research object, and presents a study on integrated optimization, which has an important theoretical significance and practical value on improving capacity and alleviating traffic congestion.The spatial range on physics and funcation of roundabout is defined and the length of spatial range is calculated. The logic of signalized control and operation rule of traffic are analyzed by summarizing different signalized control modes for signalized roundabouts. The key points of temporal and spatial resource optimization is put forward after proposing chosen principle of temporal and spatial elements. Based on field data, rules of vehicle arriving, departing and speed are studied.Synergetics is taken as an example when the concept of integrated optimization on temporal and spatial resource is desctipted. The applicability of synergetics for signalized roundabout is proofed. And the optimization object, relevant evaluation index and principle are given.Considering the restriction on capacity of circuit and conflict characteristics, the theoretical capacity of signalized roundabout is calculated by using stop line method and conflict point method. With vehivle arriving and departing curve, the calculation method of control delay is proposed by taking travel time of left-turn vehicles and offset time between the first and second stop line into consideration.Using precedence graph, the phase sequence of signalized roundabout is designed. Based on integrated optimization strategy, temporal and spatial resources is changed into constraints from t timing, lane function and capacity. The integrated optimization of temporal and spatial resources is finally transformed to a non-linear programming with the object of minimum cycle and control delay.