中文摘要：

通过对上海市内环线高架若干路段的大量实测，获取了描述高架路交通宏观特征的交通流参数分布曲线．采用非线性最小二乘拟合方法，对交通流性质进行分析，得到2种不同形式的速度-密度关系式，并据此得出畅行速度与阻塞密度这2个重要的交通流临界参数．分析结果表明．指数形式的速度-密度关系适用于描述相对稀疏的交通流；双曲形式适用于描述较拥挤的交通流．

英文摘要：

The curves of traffic flow parameters describing the traffic macroscopic characteristics are acquired by conducting a series of field measurements on several sections of the Inner Ring Elevated Road in Shanghai City. The fitting method of nonlinear least square is adopted in data processing. Two speed-density relations are worked out based on the analysis of traffic flow, thus two important critical parameters, namely, the free flaw speed and the jamming density are determined. The results show that exponential speed-density relation is suitable for the free flow while the hyperbolic relation for the congested flow.