High pressures in room evacuation processes and a first approach to the dynamics around unconscious pedestrians

The fundamental diagram of pedestrian dynamics gives the relation between the density and the flow within a specific enclosure. It is characterized by two distinctive behaviors: the free-flow regime (for low densities) and the congested regime (for high densities). In the former, the flow is an increasing function of the density, while in the latter, the flow remains on hold or decreases. In this work, we perform numerical simulations of the pilgrimage at the entrance of the Jamaraat bridge (pedestrians walking along a straight corridor) and compare flow-density measurements with empirical measurements made by Helbing et al [1]. We show that under high density conditions, the basic Social Force Model (SFM) does not completely handle the fundamental diagram reported in empirical measurements. We use analytical techniques and numerical simulations to prove that with an appropriate modification of the friction coefficient (but sustaining the SFM) it is possible to attain behaviors which are in qualitative agreement with the empirical data. Other authors have already proposed a modification of the relaxation time in order to address this problem. In this work, we unveil the fact that our approach is analogous to theirs since both affect the same term of the reduced-in-units equation of motion. We show how the friction modification affects the pedestrian clustering structures throughout the transition from the free-flow regime to the congested regime. We also show that the speed profile, normalized by width and maximum velocity yields a universal behavior regardless of the corridor dimensions.

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“…Scenarios described in Refs. [10,11,12] required, however, a step up implementation although sustaining the basic model and its parameters.…”

Section: Introductionmentioning

confidence: 99%

A re-examination of the role of friction in the original Social Force Model

et al. 2020

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“…We calculated the fraction of agents that withstand fatal pressures according to the criteria introduced in Ref. [53]. We found that the vestibule reduces the fraction of agents exposed to dangerous pressures.…”

Section: The Three-entry Vestibulementioning

confidence: 99%

Improving competitive evacuations with a vestibule structure designed from panel-like obstacles

Sticco,

Frank,

Dorso

2021

Preprint

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It has been shown that placing an obstacle in front of an exit door has proven to be a successful method to improve pedestrian evacuations. In this work, we will focus on the space limited by the exit and the obstacles (i.e. the vestibule structure). We analyzed two different types of vestibules: the twoentry vestibule (which consists of a single panel-like obstacle) and the three-entry vestibule (which consists of two panel-like obstacles). In the former, we studied the effects of varying the walls' friction coefficient κ w and the distance from the obstacle to the exit door d. In the latter, we varied the space between the two panels (gap). We found that the three above mentioned parameters control the vestibule's density, which subsequently affects the evacuation flow (fundamental diagram). We have also found that reducing the distance d or increasing the friction facilitates the formation of blocking clusters at the vestibule entries, and hence, diminishes the density. If the density is too large or too low, the evacuation flow is suboptimal, whereas if the density is around 2 p/m 2 , the flow is maximized. Our most important result is that the density (and therefore the evacuation flow) can be precisely controlled by κ w , d, and the gap. Moreover, the three-entry vestibule produced the highest evacuation flow for specific configurations of the gap and the distance from the panels to the door.

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“…[29]. Also, the compression coefficient κ n was set equal to 2.62 × 10 4 N m −1 , according to the experimental value of the human torso stiffness [30].…”

Section: Numerical Simulationsmentioning

confidence: 99%

Microscopic dynamics of the evacuation phenomena

Cornes¹,

Frank²,

Dorso³

2020

Preprint

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We studied the room evacuation problem within the context of the Social Force Model. We focused on a system of 225 pedestrians escaping from a room in different anxiety levels, and analyzed the clogging delays as the relevant magnitude responsible for the evacuation performance. We linked the delays with the clusterization phenomenon along the faster is slower and the faster is faster regimes. We will show that the faster is faster regime is characterized by the presence of a giant cluster structure (composed by more than 15 pedestrians), although no long lasting delays appear within this regime. For this system, we found that the relevant structures in the faster is slower regime are those blocking clusters that are somehow attached to the two walls defining the exit. At very low desired velocities, very small structures become relevant (composed by less than 5 pedestrians), but at intermediate velocities (v d 3 m/s) the pedestrians involved in the blockings increases (not exceeding 15 pedestrians).

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High pressures in room evacuation processes and a first approach to the dynamics around unconscious pedestrians

Cited by 33 publications

References 17 publications

A re-examination of the role of friction in the original Social Force Model

A re-examination of the role of friction in the original Social Force Model

Improving competitive evacuations with a vestibule structure designed from panel-like obstacles

Microscopic dynamics of the evacuation phenomena

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