Model of estimating time-varying OD flows for expressway corridors

On the basis of mainline traffic counts and ramp flow measurements, this research presents a dynamic system model and its on-line estimation algorithm for time-varying expressway origin-destination matrices. The proposed model employs a macro-traffic flow model to estimation travel times of OD flows and uses parameters of the traffic model as state variables, which adds to the constraint function of the system. The research employs a newly developed filtering technique, called Unscented Kalman Filter(UKF). The proposed model is evaluated with simulation experiments. The results indicate that the proposed method is reasonably and stable.