Abstract: This paper novelly introduces the least-square method for dynamically estimating traffic state in urban road system. Using GPS data of taxis, it establishsd a model to compute the states of traffic flow in a city road network. The boundary conditions, the degenerated cases of the model, illness condition of least-square algorithm are well considered in the research. The experiments show that the model is correct and can be used in many applications of intelligent transportation system.

Key words: GPS, Least-square method, Degenerated model, Boundary condition

摘要： 把最小二乘法理论运用到了城市交通流领域，在车载GPS数据基础上进行城市路网交通流拥堵状态估计。在具体实现过程中，分析解决了最小二乘法存在的问题，提出了拟和模型的退化处理、增加路网中路段连接处的边界条件等新思路。实践证明了这种处理方法的实用性，在工程中具有十分重要的意义。

关键词: GPS, 最小二乘法, 退化模型, 边界条件