Studies on traffic signal optimization combined with user equilibrium assignment

Based on interdependence between signal timing and route choices, a bi-level programming is formulated, which focuses on optimizing area-coordinated multiphase pretimed control. The lower level is user equilibrium with link capacity constraints, and directional impedance is introduced into congested networks. In the upper level, a performance index composed of travel time and stop times is criterion for optimization, and multiphase pretimed signal control model is developed. Multiplier method is used to solve the user equilibrium of the lower level. Sensitivity analysis algorithm is employed to solve the bi-level programming.