12 research outputs found
The Dynamics of Crowd Disasters: An Empirical Study
Many observations in the dynamics of pedestrian crowds, including various self-organization phenomena, have been successfully described by simple many-particle models. For ethical reasons, however, there is a serious lack of experimental data regarding crowd panic. Therefore, we have analyzed video recordings of the crowd disaster in Mina/Makkah during the Hajj in 1426H on January 12, 2006. They reveal two subsequent, sudden transitions from laminar to stop-and-go and ``turbulent'' flows, which question many previous simulation models. While the transition from laminar to stop-and-go flows supports a recent model of bottleneck flows [D. Helbing et al., Phys. Rev. Lett. 97, 168001 (2006)], the subsequent transition to turbulent flow is not yet well understood. It is responsible for sudden eruptions of pressure release comparable to earthquakes, which cause sudden displacements and the falling and trampling of people. The insights of this study into the reasons for critical crowd conditions are important for the organization of safer mass events. In particularly, they allow one to understand where and when crowd accidents tend to occur. They have also led to organizational changes, which have ensured a safe Hajj in 1427H
Dynamics of crowd disasters: An empirical study
Many observations in the dynamics of pedestrian crowds, including various
self-organization phenomena, have been successfully described by simple
many-particle models. For ethical reasons, however, there is a serious lack of
experimental data regarding crowd panic. Therefore, we have analyzed video
recordings of the crowd disaster in Mina/Makkah during the Hajj in 1426H on
January 12, 2006. They reveal two subsequent, sudden transitions from laminar
to stop-and-go and ``turbulent'' flows, which question many previous simulation
models. While the transition from laminar to stop-and-go flows supports a
recent model of bottleneck flows [D. Helbing et al., Phys. Rev. Lett. 97,
168001 (2006)], the subsequent transition to turbulent flow is not yet well
understood. It is responsible for sudden eruptions of pressure release
comparable to earthquakes, which cause sudden displacements and the falling and
trampling of people. The insights of this study into the reasons for critical
crowd conditions are important for the organization of safer mass events. In
particularly, they allow one to understand where and when crowd accidents tend
to occur. They have also led to organizational changes, which have ensured a
safe Hajj in 1427H
From crowd dynamics to crowd safety: A video-based analysis
The study of crowd dynamics is interesting because of the various
self-organization phenomena resulting from the interactions of many
pedestrians, which may improve or obstruct their flow. Besides formation of
lanes of uniform walking direction and oscillations at bottlenecks at moderate
densities, it was recently discovered that stop-and-go waves [D. Helbing et
al., Phys. Rev. Lett. 97, 168001 (2006)] and a phenomenon called "crowd
turbulence" can occur at high pedestrian densities [D. Helbing et al., Phys.
Rev. E 75, 046109 (2007)]. Although the behavior of pedestrian crowds under
extreme conditions is decisive for the safety of crowds during the access to or
egress from mass events as well as for situations of emergency evacuation,
there is still a lack of empirical studies of extreme crowding. Therefore, this
paper discusses how one may study high-density conditions based on suitable
video data. This is illustrated at the example of pilgrim flows entering the
previous Jamarat Bridge in Mina, 5 kilometers from the Holy Mosque in Makkah,
Saudi-Arabia. Our results reveal previously unexpected pattern formation
phenomena and show that the average individual speed does not go to zero even
at local densities of 10 persons per square meter. Since the maximum density
and flow are different from measurements in other countries, this has
implications for the capacity assessment and dimensioning of facilities for
mass events. When conditions become congested, the flow drops significantly,
which can cause stop-and-go waves and a further increase of the density until
critical crowd conditions are reached. Then, "crowd turbulence" sets in, which
may trigger crowd disasters