Association of Signal-Controlled Method at Roundabout and Delay

The uncontrolled roundabout is only applicable to smaller vehicle flows. With increasing of roundabout flows, series of problems have occurred in respect of traffic jams and accidents. Arrangement of signal control will help to improve delay and safety at roundabout while differences exist between condition of adaptability and traffic efficiency under different signal controlling methods. It is on the basis of “The Secondary Control Theory on Left-turn at Circular Road” that this text is aimed at mainly introducing the two different control methods of “Control of Orderly Discharge Clockwise at Single Entrance Lanes” and “Control of Synergistic Discharge at Multi Entrance Lanes”. Everything is done in consideration of roundabout with different amount of entrance lanes and based on the control theory of traffic signal and the optimization method. In this foundation, by applying methods of numeric calculation and experimental traffic engineering, we analyze the influence law on the average delay of vehicles caused by the signal cycle of time-space strategic parameters and radius of central island. The research result will help to improve the theoretical system concerning signal-controlled circus road and will also provide technical support to the reconstruction of uncontrolled circus road and to the mode selection of signal control for circus road, which is of important application value in practice.