Experimental Features of Urban Freeway Traffic Flow

Urban freeway congestion has become one of the most major and costly problems in metropolitan areas. Consequently, there is a need to study the properties of traffic flow, so that new techniques for forecasting and mitigating traffic congestion can be developed. In this paper, investigations of a great number of measurements of traffic flow on Shanghai North-South Freeway show that there are some macroscopic properties of urban freeway traffic flow. We study the spatial-temporal features of traffic congestion and parameter features of normal traffic flow, and get conclusions that the relations between traffic flow parameters of traffic bottleneck are consistent with traditional traffic flow theory, and phase transitions are observed in profiles of traffic flow fundamental parameters.