A Study of the Evolution of Traffic Flow Dynamic of a Disequilibrium Network

To describe the cost-flow relationship of disequilibrium traffic flow,a function for modeling dynamic travel time is established considering the carrying cost and travel time.A flow model of dynamic traffic is developed based on total travel cost,path flow,link travel time and coupled with a user equilibrium model.A numerical simulation is car-ried out using a simple network and the fourth order Runge-Kutta method to test the created model.Under the elastic de-mand of dynamic model,travel cost ranges from large to small,then approaches to an equilibrium value.After a rapid in-crease of path flow,with a smaller adjusting range,it tends to approach to an equilibrium value.After a rapid increase in travel time,it gradually approaches to an equilibrium value.The travel cost of fixed demand,flow path and travel time approach to an equilibrium value after repeating adjustments several times with a small range.The simulation results show that the model can accurately describe the adjustment process of network traffic flow from one disequilibrium statue to another.