3,151 research outputs found
Crowd Disasters as Systemic Failures: Analysis of the Love Parade Disaster
Each year, crowd disasters happen in different areas of the world. How and
why do such disasters happen? Are the fatalities caused by relentless behavior
of people or a psychological state of panic that makes the crowd 'go mad'? Or
are they a tragic consequence of a breakdown of coordination? These and other
questions are addressed, based on a qualitative analysis of publicly available
videos and materials, which document the planning and organization of the Love
Parade in Duisburg, Germany, and the crowd disaster on July 24, 2010. Our
analysis reveals a number of misunderstandings that have widely spread. We also
provide a new perspective on concepts such as 'intentional pushing', 'mass
panic', 'stampede', and 'crowd crushs'. The focus of our analysis is on the
contributing causal factors and their mutual interdependencies, not on legal
issues or the judgment of personal or institutional responsibilities. Video
recordings show that, in Duisburg, people stumbled and piled up due to a
'domino effect', resulting from a phenomenon called 'crowd turbulence' or
'crowd quake'. Crowd quakes are a typical reason for crowd disasters, to be
distinguished from crowd disasters resulting from 'panic stampedes' or 'crowd
crushes'. In Duisburg, crowd turbulence was the consequence of amplifying
feedback and cascading effects, which are typical for systemic instabilities.
Accordingly, things can go terribly wrong in spite of no bad intentions from
anyone. Comparing the incident in Duisburg with others, we give recommendations
to help prevent future crowd disasters. In particular, we introduce a new scale
to assess the criticality of conditions in the crowd. This may allow
preventative measures to be taken earlier on. Furthermore, we discuss the
merits and limitations of citizen science for public investigation, considering
that today, almost every event is recorded and reflected in the World Wide Web.Comment: For a collection of links to complementary video materials see
http://loveparadevideos.heroku.com/ For related work see
http://www.soms.ethz.c
Guidelines for assessing pedestrian evacuation software applications
This paper serves to clearly identify and explain criteria to consider when evaluating the
suitability of a pedestrian evacuation software application to assess the evacuation
process of a building. Guidelines in the form of nine topic areas identify different
modelling approaches adopted, as well as features / functionality provided by
applications designed specifically for simulating the egress of pedestrians from inside a
building. The paper concludes with a synopsis of these guidelines, identifying key
questions (by topic area) to found an evaluation
Macroscopic modeling and simulations of room evacuation
We analyze numerically two macroscopic models of crowd dynamics: the
classical Hughes model and the second order model being an extension to
pedestrian motion of the Payne-Whitham vehicular traffic model. The desired
direction of motion is determined by solving an eikonal equation with density
dependent running cost, which results in minimization of the travel time and
avoidance of congested areas. We apply a mixed finite volume-finite element
method to solve the problems and present error analysis for the eikonal solver,
gradient computation and the second order model yielding a first order
convergence. We show that Hughes' model is incapable of reproducing complex
crowd dynamics such as stop-and-go waves and clogging at bottlenecks. Finally,
using the second order model, we study numerically the evacuation of
pedestrians from a room through a narrow exit.Comment: 22 page
Can cooperation slow down emergency evacuations?
We study the motion of pedestrians through obscure corridors where the lack
of visibility hides the precise position of the exits. Using a lattice model,
we explore the effects of cooperation on the overall exit flux (evacuation
rate). More precisely, we study the effect of the buddying threshold (of
no--exclusion per site) on the dynamics of the crowd. In some cases, we note
that if the evacuees tend to cooperate and act altruistically, then their
collective action tends to favor the occurrence of disasters.Comment: arXiv admin note: text overlap with arXiv:1203.485
The Cry Wolf Effect in Evacuation: a Game-Theoretic Approach
In today's terrorism-prone and security-focused world, evacuation
emergencies, drills, and false alarms are becoming more and more common.
Compliance to an evacuation order made by an authority in case of emergency can
play a key role in the outcome of an emergency. In case an evacuee experiences
repeated emergency scenarios which may be a false alarm (e.g., an evacuation
drill, a false bomb threat, etc.) or an actual threat, the Aesop's cry wolf
effect (repeated false alarms decrease order compliance) can severely affect
his/her likelihood to evacuate. To analyse this key unsolved issue of
evacuation research, a game-theoretic approach is proposed. Game theory is used
to explore mutual best responses of an evacuee and an authority. In the
proposed model the authority obtains a signal of whether there is a threat or
not and decides whether to order an evacuation or not. The evacuee, after
receiving an evacuation order, subsequently decides whether to stay or leave
based on posterior beliefs that have been updated in response to the
authority's action. Best-responses are derived and Sequential equilibrium and
Perfect Bayesian Equilibrium are used as solution concepts (refining equilibria
with the intuitive criterion). Model results highlight the benefits of
announced evacuation drills and suggest that improving the accuracy of threat
detection can prevent large inefficiencies associated with the cry wolf effect.Comment: To be published in Physica
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