Abstract: As the modern high-grade highway, expressway has the characteristics of massinvestment,long constructing period,mass-occupation of land，heavy degree of difficulty.Soits of benefits investment is widely concerned by all society. In order to evaluate the socioeconomic benefit of expressway project objectively, it is necessary to carry on front-evaluation, and post-evaluation as well. In the paper, on the basis of investigation and analysis of economic and traffic status of Shenyang，the authors adopt systematic viewpoint，apply such theories as regional economics and feedback control，employ the analysis and simulation of system dynamic，and analyz the internal structure and dynamic conduct of the socioeconomics-traffic system. A post-evaluation SD model of the expressway socioeconomic benefit is established. Besides，a dynamic simulation for the socioeconomics-traffic system is carried out on the computer. By changing control variables and
adjusting parameters，the paper made a macroforecast for the future system’s development，on the basis of the overall aim for the evaluation of expressway socioeconomic benefit.

Key words: expressway, so cioeconomicb enefits, System Dynamics

摘要：

高速公路作为现代化的高等级公路，具有投资大、工期长、占地多、工程难度大等特点，其投资效益深受社会各方面的关注和重视.为了客观评价高速公路项目的社会经济效益，不仅需要进行立项阶段的前评估工作，而且要求在项目建成营运一段时间后，对其进行后评估工作.本文在实地调查分析沈阳市经济交通状况的基础上，以系统论的观点，运用区域经济学、反馈控制论等原理，采用系统动力学的分析和模拟方法，分析了社会经济一交通系统的内部结构和动态行为，建立了高速公路社会经济效益后评估的系统动力学模型，并在计算机上实现了社会经济一交通系统的动态仿真.同时围绕客观评价高速公路社会经济效益的总体目标，通过改变控制变量和调整控制参数的方法，对系统未来的发展趋势进行了宏观预测.

关键词: 高速公路, 社会经济效益, 系统动力学