Calculation Method of Signal Cycle at Roundabouts Considering Cross-phase Conflicts
To solve the cross-phase conflict problem in traffic flow at signalized roundabouts,this paper analyzes the vehicle trajectory within roundabout and develops a fundamental cycle equation and cross-phase interval equations based on the characteristics of phase passage time,phase interval time,and minimum phase interval time.Based on the inequality constraints of phase passage time,phase interval time and signal cycle,this paper proposes a basic signal timing model for roundabouts with the minimzed signal cycle and considers the possibility of negative total loss time in the phase design of roundabouts.The general cycle equations and inequality constraints are analyzed under different ordered phase sets.The variation of the cycle range with the flow rate of each phase are analyzed under different phase sets,and a calculation method is proposed for signal cycle range at roundabout.The simulation verification was conducted using a total flow ratio of a roundabout equal to 1.05 as an example.The results show that when signal cycle was set to the shortest signal cycle of 52 seconds,all evaluation indicators reached or approached the optimal value.The proposed method was compared with the two-stop-line-for-left-turn method and the reconstruction into a cross-intersection under three different traffic volume of entrance.It was found that the delay time and the average queue length of two roundabout control methods was reduced by 52%and 55%,compared to the cross-intersection control method.The average delay and the average queue length of the proposed method was reduced by 43%and 44%,compared with the two-stop-line-for-left-turn method,when the flow at the opposite entrance was unbalanced.In addition,taking the Huaxia-Jinsui roundabout in Guangzhou as an example,simulation analysis showed that the proposed method had the overall control benefits in terms of vehicle delay,stops and queue length.
万方数据
维普
