Probe Vehicle-based Traffic Flow Estimation Method without Fundamental Diagram

This paper proposes a method of estimating the traffic state based on new probe vehicle data that contain the spacing and position of probe vehicles. In this study, the probe vehicles were assumed to observe spacing by utilizing an advanced driver assistance system, which has been implemented in practice and is expected to spread in the near future. The proposed method relies on the conservation law of traffic flow but is independent of the fundamental diagram. The conservation law is utilized for reasonable aggregation of the spacing data to acquire the traffic state, namely flow, density and speed. Its independence from the fundamental diagram means that the method does not require any predetermined assumptions with regard to the traffic flow model parameters. The estimation performance was validated through a field experiment conducted under actual traffic conditions. The results confirmed that the proposed method can estimate the traffic state precisely, even if the probe vehicle penetration rate is quite low.