Microscopic dynamics at the Running of the Bulls (San Fermin Festival) in the context of the Social Force Model

TL;DR

This paper models pedestrian dynamics during the Running of the Bulls, revealing how fallen individuals influence nearby pedestrians' fall risk and introducing a new indicator called falling susceptibility within the Social Force Model.

Contribution

It introduces a microscopic model of stumbling behavior in the Social Force Model, highlighting the impact of fallen pedestrians on evacuation dynamics.

Findings

Fallen pedestrians significantly increase nearby pedestrians' fall probability.

The local density gradient and velocity are key indicators of imminent falls.

The model successfully replicates observed behaviors during the event.

Abstract

This research explores the dynamics of the emergency evacuation during the "Running of the Bulls" festival (Spain, 2013). As people run to escape from danger, many pedestrians stumble and fall down, while others will try to pass over them. We carefully examined three specific recordings of the running, that show this kind of behavior. We developed a microscopic model mimicking the stumbling mechanism in the context of the Social Force Model (SFM). In our model, "moving" individuals can suddenly switch to a "fallen" state when they are in the vicinity of a fallen individual. We arrived to the conclusion that the presence of a fallen pedestrian increases dramatically the falling probability of the pedestrians nearby. Also, the product between the local density gradient and the velocity of each pedestrian appears as a relevant indicator for an imminent fall. We call this the pedestrian "falling susceptibility (f_s)".