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| Conference Presentation (After Call) | FZJ-2022-04614 |
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2022
Please use a persistent id in citations: http://hdl.handle.net/2128/34146
Abstract: The relationship between density ρ flow J and velocity v of pedestrian streams is of central importance for describing the performance of facilities for pedestrian traffic. For these relations the term fundamental diagram is used, if they base on temporal or spatial averages J, v and ρ gained by empirical measurements of a system in a steady state. In manuals, standards and guidelines, the following forms are used for representing the fundamental diagram: averages v (ρ ), J (v ) and J (ρ ). For the comparison of fundamental diagrams of systems of different widths and for the transformation of these different representations, the concept of the specific flow J_s= J⁄b where b is the width of the facility and the flow equation J= ρ∙v∙b are used. It is assumed that the specific flow J_s=ρ∙v is independent of the width of the facility.In this contribution, the state of the art is summarized for fundamental diagrams of unidirectional, bidirectional and multidirectional flows. Most studies base on trajectories of the head, enabling even microscopic measurements of the ρ, J and v. The comparison of the data in the literature shows that up to now there are inconsistencies and discrepancies between different studies and measurement methods, in particular at the congested branch of the fundamental diagram, see Figure and [1,4]. Measurements of bidirectional and multidirectional flows at high densities give unexpectedly high flows and most studies do not indicate that a standstill occurs due to a high density. In a critical discussion it is analysed which problems arise from an oversimplified use of the flow equation and how measurements of ρ, J and v have to be performed to be in consistency with the continuity equation.
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