Abstract: Urban transportation system is a complex system with multiple variables and nonlinear feedback loops and influenced by transportation, social, economical, and environmental factors. Conventional transportation modeling approaches are unsuitable to simulate and evaluate its performance. This paper presents a system dynamics approach based on the cause-and-effect analysis and feedback loop structures. The proposed SD model comprises 7 submodels: population, economic development, number of vehicles, environmental influence, travel demand, transport supply, and traffic congestion. The model runs in Vensim PLE software using the data from Dalian, China. The coefficient of the intervention policy of vehicle ownership is chosen as the control variable for simulation, and the impacts of different policy scenarios on urban development and transportation system are analyzed. It suggests that Dalian should restrict the total number of vehicles to improve the sustainability of transportation system.

Key words: urban transportation system, system dynamics, vehicle ownership, intervention policy, sustainability

摘要： 城市交通系统是一个多变量、多反馈、非线性的复杂系统，它的可持续发展受交通、社会、经济、环境等多种因素的制约，而传统的交通预测模型难以模拟这样一个复杂系统的动力机制。为此，本文采用系统动力学方法，在系统结构分析和因果反馈分析的基础上建立了城市交通系统的SD (System Dynamics) 模型，包括人口、经济发展、机动车保有量、环境影响、交通需求、交通供给和交通拥挤七个子系统。以大连主城区为对象，选取影响机动化发展的政策干预因素为调控参数进行仿真，分析了不同的机动化发展政策对城市发展和城市交通系统的影响，并提出了相应的建议和对策。

关键词: 城市交通系统, 系统动力学, 机动化, 政策干预, 可持续发展