An Analytical Method of Traffic Flow Using Aerial Photographs

Abstract

The outline and results of an aerial traffic survey of an 800‐m section of the Hanshin Expressway are described. The objectives of the study were to record congested traffic flow and to determine its causes. Traffic in the study section was photographed by two 35‐mm still cameras every 5 s for 1 h. All vehicles recorded in the southbpund traffic flow were numbered and traced in order to project their trajectories in the time and space diagram. Speed and density contour diagrams were based on the theory of three‐dimensional representation of traffic flow. The characteristics and causes of traffic congestion were analyzed using these diagrams.