Abstract:The old city has a dense network of roads and lanes. The utilization of traffic microcirculation can relieve traffic pressures on the trunk roads and improve the bearing capacity and accessibility of the regional road network. Taking the saturation of trunk roads and traffic index of street level as the optimization objective and the non-congestion of branch roads as the constraint condition, the upper-level model is built. The lower-level model is solved by using the equilibrium traffic assignment of user and in virtue of TranCAD. The bi-level programming model of traffic microcirculation is established for the old city. An example is given to illustrate the process of building and solving the model.