Abstract:At isolated signalized intersections, congestion problems are caused in part by an imbalance in supply and demand, which may be caused by the variability of turning-movement volumes. Although signal timing can be adjusted to handle varying demand, the effect of this adjustment alone is limited, especially when traffic demand fluctuates significantly. A two-step optimization model for dynamic lane assignment is presented: the model overcomes the shortcoming of static lane markings and fully utilizes the existing traffic facilities. The first step is to obtain the best lane assignment scheme by using an arm-group-based integer nonlinear program model. The second step is to identify a suitable implementation scheme by determining a binary-type threshold. The results of VISSIM simulation show that the proposed model can correctly choose the occasion to change the lane assignment by ignoring the small volume fluctuation and can improve traffic operations effectively when the traffic demand varies significantly.