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Single-vehicle data of highway traffic: A statistical analysis

“…Using the auto-covariance function and cross-covariance for the different time-series we were able to identify three qualitatively different microscopic states of traffic flow, namely the free-flow, synchronized and stop-andgo traffic [20]. The free-flow states are characterized by a strong coupling of the flow and density and beyond that by a slow decay of the related auto-covariance functions.…”

“…a collapse of the flow resp. the speed emerges, the freeflow branch can only be reached again by reducing the local density [20,21]. In the data base considered here such a sharp fall is not observable since all detected jams are caused by the bottleneck downstream the detector D1.…”

“…The corresponding states exhibit meta stability, i.e. a perturbation of finite magnitude and duration is able to destroy such a high-flow state [20]. Once such terized by a large value (≈ 1) of the cross-covariance between the local density and the local flow as defined by (3) and displayed in Fig.…”