Traffic state estimation using traffic measurement from the opposing lane-an application of variational theory

In this study, we propose a method of estimating traffic conditions using the traffic data observed from the opposing lane instead of using detector data at fixed locations. The requested input data for our proposed method are (1) probe vehicle data on the study stream and (2) data obtained by the measurement vehicles running in the opposing lane. These input data identify the cumulative vehicle counts only along the trajectories of the probe and measurement vehicles in the time-space of interest. We applied the variational theory based on the kinematic wave to estimate vehicle trajectories over the entire time-space using the identified cumulative vehicle counts as the boundary condition. We analyzed the fundamental properties of the proposed method, such as the region in which vehicle trajectories can be estimated, in relation to the probe and measurement vehicle speeds. To confirm the effectiveness of the proposed method, we used traffic state data for verification by using a traffic microsimulator.