Chaotic property research for freeway traffic flow

Based on Greenshields´ model, this paper constructs a dynamic discrete traffic flow model with the form of logistic map and presents dynamic analysis for this model. By taking the occupancy as the model variable and the ratio of free flow speed to average speed as the control parameter of the model, we theoretically analyze the different traffic flow condition and the producing and transformation mechanism of chaos for freeway traffic flow. At last, we employ the largest Lyapunov exponent and power spectrum technique to estimate chaos for the real measured freeway traffic flow series so as to validate the chaotic property of freeway traffic flow series.