Coordinated Optimization of Signal Timing for Intersections with Dynamic Shared Through- and Right-Turn Lanes

Through and right-turn shared lanes are widely designed to increase the capacity of through traffic, but they can also cause delays for right-turn vehicles. This study presents a dynamic control method for a shared lane that prioritizes right-turn vehicles at the beginning of the cycle and subsequently allows through traffic to queue in the shared lane for saturated discharge. The traffic wave model is employed to reveal the dynamics of the traffic flow under this control and to derive the relationships among major traffic parameters. Constrained by the major relationship, a linear programming approach to minimize the total queue length is developed to determine the proper values of control parameters, including the shared area length, subordinate signal time lag, and shared or exclusive duration. A sensitivity analysis of the control parameters for different arrival rates and flow ratios is performed. Comparisons are conducted among the dynamic shared lane, the fixed exclusive lane, and the fixed shared lane. The results show that the dynamic control method results in a lower delay for both through and total traffic.