Research On The Road Category Structure Optimized In Big City

Urban road system planning is one of the most important content in urban traffic planning. The rationality of road category structure and the definition of functions corresponding to each road category can exert a profound influence on the result of road system planning. They will influence every traffic way combining close cooperation and coordinating each other. Further more, they will influence the convenience, velocity cosiness economy and safety of trips of passenger and cargo, the social and economic benefit of road system and the development of urban economy.First, this paper analyzes the characteristics of urban road system and discusses the thinking and functions of every classification road classified in domestic and international urban road, it points out that there are different main serivce objects on different classification road; Afterward it analyzes the interaction relation between urban land using and urban road, moreover it sets up interaction model; Then according to the division of function characteristic of city traffic unit, the travel distance distribution of urban traffic is researched, and in macroscopic view the traffic is classified into three categories: short-distance traffic, middle-distance traffic and long-distance traffic. Finally, a new concept named lever of service of road network is put forward, the mathematical models to calculate the capacity of different road category under variant lever of service of road network are given, according to the travel distance distribution of urban traffic, the rationality of road category structure is discussed. This paper also puts forward methods and measures optimizing the functions of road network, and combining researches the above, it analyzes the rationality of Xi'an current road category structure.