Abstract: Currently the trafic impact analysis(TIA)threshold of urban construction projects always adopts a single value (f.g.peak hour trip rate equals to 1OOPCU/h)，never considering the diferent trafic conditions．Aiming at this problem， based on the system of urban road equivalent capacity and density ratio evaluation，a novel method to calculate the TIA threshold is presented．According to the density ratio evaluation criterion．the urban road trafic conditions are divided into some grades and the TIA trip threshold for each grade is advanced．

Key words: trafic engineering, trafic impact analysis(TIA), threshold, equivalent capacity, density ratio

摘要： 针对目前城市建设项目交通影响分析阈值单一、未考虑道路交通状况差异性的问题，提出基于城市道路等效 通行能力和密度比的评价方法，提出新的充分考虑道路不同交通状况的交通影响分析阈值计算方法．根据密度比评 分标准，将城市道路交通状况划分为若干等级，对各等级道路提出了相应的建设项目交通影响分析出行阈值．

关键词: 城市建设项目, 交通影响分析, 阈值, 等效通行能力, 密度比