Simulation of counterflow pedestrian dynamics using spheropolygons

Abstract

Pedestrian dynamic models are typically designed for comfortable walking or slightly congested conditions and typically use a single disk or combination of three disks for the shape of a pedestrian. Under crowd conditions, a more accurate pedestrian shape has advantages over the traditional single or three-disks model. We developed a method for simulating pedestrian dynamics in a large dense crowd of spheropolygons adapted to the cross section of the chest and arms of a pedestrian. Our numerical model calculates pedestrian motion from Newton's second law, taking into account viscoelastic contact forces, contact friction, and ground-reaction forces. Ground-reaction torque was taken to arise solely from the pedestrians' orientation toward their preferred destination. Simulations of counterflow pedestrians dynamics in corridors were used to gain insight into a tragic incident at the Madrid Arena pavilion in Spain, where five girls were crushed to death. The incident took place at a Halloween Celebration in 2012, in a long, densely crowded hallway used as entrance and exit at the same time. Our simulations reconstruct the mechanism of clogging in the hallway. The hypothetical case of a total evacuation order was also investigated. The results highlights the importance of the pedestrians' density and the effect of counterflow in the onset of avalanches and clogging and provides an estimation of the number of injuries based on a calculation of the contact-force network between the pedestrians.

Redefining the role of obstacles in pedestrian evacuation

“…Despite that this phenomenon must be confirmed by further experiments in which other obstacle diameters and shapes as well as more competitiveness levels are implemented, our work challenges the validity of most of the existent models in which there is always a given range of obstacle positions for which the flow rate improves (with more or less efficacy depending on the obstacle properties). This hints about the necessity of revisiting, for the case of highly competitive conditions, some numerical aspects (such as the route choice [41] at spatial scales smaller than one metre) and/or incorporating new ones (such as the individuals shape [42,43] and the preferred orientation in the displacement [44,45]). Moreover, we discovered that placing an obstacle in front of the exit reduces the magnitude and number of collective transversal displacements, suggesting that its implementation would be beneficial in preventing falls.…”

Flow and clogging of a sheep herd passing through a bottleneck

“…But these experiments are not carried out in a competitive situation because of obvious ethics considerations. And, third, computer simulations [6][7][8][9] are inspiring and useful, but the rules embodied in the underlying models are difficult to test with controlled experiments, thus limiting their value.…”

Simulating competitive egress of noncircular pedestrians

“…Despite the undoubtable novelty of these works, we must note that they were implemented in a noncompetitive regime where it is expected that contact and friction are not as relevant as in the competitive scenario. In the only antecedent we are aware of, pedestrians are simulated with shapes different to the disk in competitive conditions in the work of Alonso-Marroquín et al [25]. They describe the shape of a human body [its two-dimensional (2D) transversal section at chest height] using spheropolygons and considered the normal and tangential contact forces between pedestrians.…”