Method And Simulation Of Multi-approach Collaborative Release At The Signalized Roundabout

The traffic efficiency of non-signalized roundabouts is reduced when vehicle speed low,conflicts of weaving areas and other problems at large traffic volume,which led to dissatisfaction of traffic demands.Considering factors such as urban landscape and cost,implementation of signal lamp control is an important approach for improve the traffic efficiency of roundabout.However,compared with conventional intersections and non-signalized roundabouts,the traffic operation characteristics of actual signalized roundabouts are complicated due to influences from road channelization design,traffic flow,control modes and driving behavior,and the characteristics were distinctly different at different signal control modes.Especially,it is found that is difficult to reach the ideal signal control effect when mutual interference between circulating vehicles of the signalized roundabout.The paper proposed a new signal control method based on rational channelization design of roundabouts,which to avoid mutual interference between circulating vehicles,and expecting to reduce the vehicle delay and improve the traffic efficiency of the signalized roundabout.Firstly,the paper summarized characteristics and applicable conditions of the current signal control methods of roundabouts,and analyzed traffic operation characteristics of signalized roundabout in combination with current research results and measured data.Then,the paper established a traffic flow model which can describe traffic operation characteristics of signalized roundabout based on the cell transmission model.Through comparison and analysis with measured data,the effectiveness of the traffic flow model of signalized roundabouts is verified.Secondly,considering the traffic operation characteristics of signalized roundabouts,especially influences of mutual interference between circulating vehicles on vehicle delay of the roundabouts,the paper proposed a multi-approach collaborative release signal control method based on the premise that left-turning flow at the entrance and straight-through flow at an anticlockwise-adjacent entrance have the same destination exit.The paper established a signal optimization model with intersection delay as the optimization goal and timing parameters as target variables based on the established traffic flow model of signalized roundabouts.The signal timing parameters were obtained through optimization with the genetic algorithm.Finally,the traffic flow model and the signal optimization model of signalized roundabouts were simulated based on application of the MATLAB programming software,while the genetic algorithm was used for solving the optimization model.Taking a typical four-leg roundabout as an example,the validity of the proposed multiapproach collaborative release signal control method and the established signal optimization model was verified.