Automatic fitting procedure for the fundamental diagram

作者：Knoop Victor L^*; Daamen Winnie

来源：Transportmetrica B-Transport Dynamics, 2017, 5(2): 133-148.

DOI：10.1080/21680566.2016.1256239

• Fundamental diagram
• fitting
• freeway
• wave speed
• free flow speed
• capacity drop
• calibration

The fundamental diagram of a road, including free-flow capacity and queue discharge rate, is very important for traffic engineering purposes. In the real word, most traffic measurements come from stationary loop detectors. This paper proposes a method to fit Wu's fundamental diagram to loop detector data. Wu's fundamental diagram is characterised by five parameters, being free-flow speed, wave speed, free-flow capacity, queue discharge rate and jam density. The proposed method entails fixing the wave speed and the free-flow speed. The method consists of two steps. We first use a triangular fundamental diagram to separate the congested branch from the free-flow branch. Then, the remaining three parameters of Wu's fundamental diagram are fitted on each branch using a least-square fit. This method is shown to be robust for cases tested in real life, and hence very noisy,data.

• 出版日期2017