The microscopic characteristics of escape behaviours from a three-dimensional lecture theatre under conditions of good and zero visibility

Abstract The microscopic characteristics of escape behaviours from a three-dimensional space containing stairs have huge influence on the evacuation efficiency, the formation of congestion and the safety of pedestrians, since if emergency occurred, a misplaced step of pedestrians can result in serious injury if it leads to a fall. In this paper, a series of human evacuation experiments under conditions of good and zero visibility are firstly performed in a 3D lecture theatre. It is demonstrated that the swaying of trajectories both laterally and vertically are essentially caused by the human biomechanical features. Observation of the video recording and trajectories reveals several typical forms of behaviour related to route choice, evacuation direction and following behaviour under zero visibility, which are distinctly different from those in normally lit conditions. Moreover, there exist two high density areas for normally lit and blind evacuations: the exit area and the transition region between the stairs and the ground in the aisle, but the congestion in the aisle is more serious when visibility decreases to zero. Based on experimental observation and analysis, we propose a 3D social force model by introducing two lateral and vertical oscillation forces to reproduce the realistic swaying characteristic of pedestrians escaping from a 3D lecture theatre. Finally, simulations with the same setup as the real-life experiments are carried out using the proposed 3D model considering swaying, and the simulated evacuation speed curves, swaying trajectories, density profiles as well as pedestrian position distributions all demonstrate remarkable consistence with the experimental results.