Estimation of the Density Field of Automobile Traffic Flow at the Bottleneck

Abstract

Analysis of relation between flow speed and jam condition of automobile traffic flow on an expressway is neccesary to achieve appropriate traffic flow. A jam condition on an expressway is caused at the bottleneck points like the entrance of tunnels and others. So it is very important to grasp the flow condition at the bottleneck for analysis and estimation of automobile traffic flow. As the change of flow density is explained by flow demand and flow capacity at the bottleneck point, the estimation method of density field at upstream part and down stream part of the bottleneck point is reported on this paper using the characteristic lines method. And this paper reports that this method is also useful to analyze the density behavior by increasing and decreasing of vehicle number at the merging points and the diverging points of an interchange on an expressway.