Unimpeded Mode of Underground Space in the City Center

Because of the fast development of city in our country,the conflict between development of city center and the capacity of transportation is increasingly acute.It has been the important factor which influences the progress of economy and society in the cities.The city center is the core district of the city,it's the economic,politic and cultural center of one city or even all the disticts.where a lot of public buildings and the third industries are concentrated,It is the junction of commodity,people and traffic,and also is the vital point of main roads and outward roads of the city.So,it's transportation flow is much larger than that in other districts of the city.In order to resolve the transportation problem in the city center,this text will study the development and use of underground space from the aspect of stereoscopic separation type of transportation,and refer to the unimpeded mode of transportation in the city center.