Theoretical vs. Empirical Classification and Prediction of Congested Traffic States
Starting from the instability diagram of a traffic flow model, we derive conditions for the occurrence of congested traffic states, their appearance, their spreading in space and time, and the related increase in travel times. We discuss the terminology of traffic phases and give empirical evidence for the existence of a phase diagram of traffic states. In contrast to previously presented phase diagrams, it is shown that “widening synchronized patterns” are possible, if the maximum flow is located inside of a metastable density regime. Moreover, for various kinds of traffic models with different instability diagrams it is discussed, how the related phase diagrams are expected to approximately look like. Apart from this, it is pointed out that combinations of on- and off-ramps create different patterns than a single, isolated on-ramp.
KeywordsTraffic Flow Traffic State Congested Traffic Traffic Model Fundamental Diagram
DH and MT are grateful for the inspiring discussions with the participants of the Workshop on “Multiscale Problems and Models in Traffic Flow” organized by Michel Rascle and Christian Schmeiser at the Wolfgang Pauli Institute in Vienna from May 5–9, 2008, with partial support by the CNRS. Furthermore, the authors would like to thank for financial support by the Volkswagen AG within the BMBF research initiative INVENT and the Hessisches Landesamt für Straßen und Verkehrswesen for providing the freeway data.
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