arXiv subjects

Ann Katrin Boomers

Publications and source records attributed to Ann Katrin Boomers.

4 recordsLinked to original sources

arXiv2025

Pedestrian Flow Analysis in High-Density Crowds: Continuity Equation with Voronoi-Based Fields

Since the beginning of the century, capturing trajectories of pedestrian streams precisely from video recordings has been possible. To enable measurements at high density, the heads of the pedestrians are marked and tracked, thus providing a complete representation of the phase space. However, classical definitions of flow, density, and velocity of pedestrian streams are based on different segments in phase space. In addition, traditional methods fail with high densities of people, as heads move even when a crowd is blocked and standing still. In this article, Voronoi decomposition is used to construct density and velocity fields from pedestrian trajectories to solve this problem. Combined with the continuity equation, a flow equation on the basis of trajectories is derived satisfying the conservation of particle numbers exactly. The proposed method allows definitions of all quantities in the same segment of phase space even on scales smaller than the dimensions of a pedestrian. It is shown that these new definitions of flow, density, velocity are consistent with classical measurements and make it possible to determine standstill in pedestrian flows even when individual body parts are moving. These properties allow to scrutinize inconsistencies in the state of the art of pedestrian fundamental diagrams.

physics.soc-ph↗

arXiv2023

Together apart: the influence of increased crowd heterogeneity on crowd dynamics at bottlenecks

Individual differences in mobility (e.g., due to wheelchair use) are often ignored in the prediction of crowd movement. Consequently, engineering tools cannot fully describe the impact of vulnerable populations on egress performance. To contribute to closing this gap, we performed laboratory experiments with 25 pedestrians with varying mobility profiles. The control condition comprised only participants without any additional equipment; in the luggage condition and the wheelchair condition, two participants at the center of the group either carried suitcases or used a wheelchair. We found that individuals using wheelchairs and to a lesser degree those carrying luggage needed longer to pass through the bottleneck, which also affected those walking behind them. This led to slower times to fully clear the bottleneck in the wheelchair and luggage condition compared to the control group. The results challenge the status quo in existing approaches to calculating egress performance and other key performance metrics in crowd dynamics.

physics.soc-ph↗

arXiv2023

Exploring Perceived Vulnerability of Pedestrians: Insights from a Forced-Choice Experiment

Individual differences in mobility (e.g., due to wheelchair use) during crowd movement are not well understood. Perceived vulnerability of neighbors in a crowd could affect, for example, how much space is given to them by others. To explore how pedestrians perceive people moving in front of them, in particular, how vulnerable they believe them to be, we asked \SI{51}{} participants to complete a Two-Alternatives-Forced Choice task (2AFC) in an internet browser. Participants were shown pairs of images, each showing a person, and then asked to select the person who appeared more vulnerable to them. For example, participants would choose between a male person in a wheelchair and a female person carrying a suitcase. In total 16 different stimuli (male vs female; no item/device, 1 suitcase, 2 suitcases, small backpack, large backpack, stroller, cane, and wheelchair), yielding n(n-1)/2 = 120 potential pairwise comparisons per participant. Results showed that wheelchair users appeared the most vulnerable and persons without any items/devices the least vulnerable. Persons carrying two suitcases were in the middle. These results informed the design of a main behavioral study (not reported here).

physics.soc-ph↗

arXiv2023

Pedestrian Crowd Management Experiments: A Data Guidance Paper

Understanding pedestrian dynamics and the interaction of pedestrians with their environment is crucial to the safe and comfortable design of pedestrian facilities. Experiments offer the opportunity to explore the influence of individual factors. In the context of the project CroMa (Crowd Management in transport infrastructures), experiments were conducted with about 1000 participants to test various physical and social psychological hypotheses focusing on people's behaviour at railway stations and crowd management measures. The following experiments were performed: i) Train Platform Experiment, ii) Crowd Management Experiment, iii) Single-File Experiment, iv) Personal Space Experiment, v) Boarding and Alighting Experiment, vi) Bottleneck Experiment and vii) Tiny Box Experiment. This paper describes the basic planning and implementation steps, outlines all experiments with parameters, geometries, applied sensor technologies and pre- and post-processing steps. All data can be found in the pedestrian dynamics data archive.

physics.soc-ph↗