Forward propagation of a push through a row of people

Security plays a crucial role when it comes to planning large events such as concerts, sporting tournaments, pilgrims, or demonstrations. Monitoring and controlling pedestrian dynamics can prevent dangerous situations from occurring. However, little is known about the specific factors that contribute to harmful situations. For example, the individual response of a person to external forces in dense crowds is not well studied. In order to address this gap in knowledge, we conducted a series of experiments to examine how a push propagates through a row of people and how it affects the participants. We recorded 2D head trajectories and 3D motion capturing data. To ensure that different trials can be compared to one another, we measured the force at the impact. We find that that the propagation distance as well as the propagation speed of the push are mainly functions of the strength of the push and in particular the latter depends on the initial arm posture of the pushed participants. Our results can contribute to a deeper understanding of the microscopic causes of macroscopic phenomena in large groups, and can be applied to inform models of pedestrian dynamics or validate them, ultimately improving crowd safety.