Abstract: The study on the impedance function of urban road in diferent grade is very important to the ITS. The paper firstly analyzes the characters of the expressway and the main-road in megalopolis, and gives out the form of their impedance function. On the basis of the observed date, the paper analyzes the relation between the speed and traffic flow on the section of the expressway and the main-road, then according to this relation, it discusses the characters of the impedance function and the form that they adapt to. As the keystone of all the paper, the delay of vehicles through intersections is emphasized. And then the paper constructs a unified model to compute the average delay of vehicles passing any type of intersections, designs a method to check it out, verifies it from real data researched, and proposes the models of the expressway and the main-road in urban.

Key words: express way, velocity, main-road way, delay, impedance function, intersection

摘要： 城市道路分等级路阻函数的研究对智能交通系统(ITS)至关重要，本文首先分
析了大城市快速路以及主干路的特点，并给出了相应的路阻函数的形式，并基于实际调查数据分析了城市快速路及主干路路段的车速与交通量的关系，通过得到的关系论述了两等级道路的路段路组函数的特点及适应形式。并重点针对主干路的交叉口延误计算进行研究，建立了适应各类型交又口延误计算的统一模型，设计了延误计算公式的检验方法，并通过实际调查数据进行了模型的检验.最后确定了城市快速路与主干路路阻函数的模型。

关键词: 快速路, 主干路, 车速, 延误, 路阻函数, 交叉口