Study On The Growth Mechanism Of Urban Rail Transit Network Based On System Dynamics

Under the backgrounds of urban space expanding, urban population increasing andthe contradiction of traffic supply and demand becoming increasingly prominent year byyear, the construction of urban rail transit (URT) systems has become the importantstrategic act to optimize transportation structure and ease traffic congestions for domesticand international metropolises. The URT construction experiences of domestic andinternational metropolises show that URT is increasingly becoming the most importanttransportation guarantee and driving force for urban development. It is a growth progressof URT network from the beginning of construction to the gradual improvement, which issubject to capital, land, traffic demand and other factors. This growth process involves themechanism analysis and decisions of construction opportunity, construction scale, networklayout, construction order and schedule. Based on the analysis of domestic andinternational research results, this paper creates a new method to analyze URT networkgrowth schedule quantitatively using System Dynamics, considering the supply anddemand dynamic balance and the interaction between urban development and URTconstruction.Firstly, this paper illustrates the intensions and key pionts of URT network growthmechansim, and shows that the essence of the growth mechanism is the interactionbetween URT and urban development. URT network growth should match the phases ofurban development.Futhermore, the factors that URT network growth should consider in early phase andmidddle and later phase are analyed. The system dynamics models based on capitalconstraints and based on supply&demand coordination are established seperately. URTconstruction in Wuhan is also analyzed as the case study, and the model calibration andquantitative simulation are conducted to predict the future URT network developmentprocess at different stages. In the model, different URT network growth schedule can besimulated by changing the policy variables, thus the relevant policy recommendations areadvised. Finally, the optimal length of rail transit line model is established with the backgroundof a single-central city, which sets the rail transit net income maximization as the objectivefunction, considering the competition and cooperation among different transport modes inthe traffic network. And an empirical research is conducted numerically.