近些年来,随着我国经济建设的飞速发展及城市化程度的不断提高,许多大中城市的规划布局已发生很大改变,其特点是市中心人口疏散和市郊居住区扩大。城市中原有的生活空间被第三产业的机构所取代,这便造成就业和居住人口愈加不平衡,而且增加了进出城市的交通量,结果就使得道路系 In recent years, with the rapid development of China’s economy and the ever-increasing degree of urbanization, the planning and layout of many large and medium-sized cities have undergone great changes. Their characteristics are the evacuation of urban centers and the expansion of suburban settlements. The fact that the original living space in the city was replaced by the establishment of the tertiary sector resulted in an increasingly unbalanced employment and housing population and an increase in traffic to and from the cities. As a result, the road system