基于系统动力学的城市交通系统供需分析模型

城市交通系统是一个多变量、多反馈、非线性的复杂系统，系统各要素之间相互制约，科学合理地描述其动力机制十分重要。采用系统动力学的方法，确定城市交通系统的界限，在具体分析系统内部各要素因果反馈作用关系和构建系统流图的基础上，建立城市交通系统动力学模型，重点对城市交通系统供需关系进行研究并给出模型的主要方程。以西安市为例，进行模型的模拟仿真，预测供需关系的发展趋势并进行分析，结果表明远期供需比例会出现严重失衡，而采取限制机动车出行需求的转化、发展城市公共交通系统等合理的交通需求管理政策可以在一定程度上缓解交通供需矛盾。

Supply demand analysis model of urban traffic system based on system dynamics

Urban transportation system is a multi variable, multi feedback, and nonlinear complex system. There are mutual restrictions between its elements, and it is necessary to scientifically describe the dynamic mechanism of this system. This paper set the boundary of urban traffic system by use of the method of system dynamics, analyzed the causal feedback effect relations between various elements of the internal system, and presented a flow chart of urban transportation system. Based on that, a system dynamics model of urban traffic system was established, and the relationship between supply and demand of urban traffic system was studied to present the main equations of the model. Taking Xi’an as an example, this paper simulated the model and estimated the development trend of supply and demand. The analysis results show that there are serious imbalances in the proportion of long term supply and demand. Some proper traffic demand management policies can be adopted to ease the contradiction between demand and supply, such as taking Transit Priority Policy, developing urban public traffic system.