A novel social distance model reveals the sidewall effect at bottlenecks

Abstract

Intermittent and periodic outbreaks of infectious diseases have had profound and lasting effects on societies throughout human history. During the global spread of SARS-CoV-2 and the resulting coronavirus disease (COVID-19), social distance has been imposed worldwide to limit the spread of the virus. An additional deliberate intention of keeping a minimum safety distance from neighbors can fundamentally alter the “social force” between individuals. Here, we introduce a new “social distance” term inspired by gas molecular dynamics and integrate it into an existing agent-based social force model to describe the dynamics of crowds under social-distanced conditions. The advantage of this “social distance” term over the simple increasing of the repulsive range of other alternatives is that the fundamental crowd properties are precisely described by our model parameters. We compare the new model with the Helbing and Molnar’s classical model and experimental data, and show that this new model is superior in reproducing experimental data. We demonstrate the usability of this model with a bottleneck motion base case. The new model shows that the bottleneck effect can be significantly alleviated through small wall modifications. Lastly, we explain the mechanism of this improvement and conclude that this improvement is due to spatial asymmetry.

Crowd dynamics research in the era of Covid-19 pandemic: Challenges and opportunities

“…The existing evidence shows that the dominant tendency is still to resort to the coefficients of repulsive force in order to control this feature, i.e., inter-agent distances. However, the extent to which this parameter guarantees that agents maintain the distance dictated to them is questionable ( Si and Fang, 2021 ). Researchers that have worked with social force models are aware that depending on the size of the crowd and a range of other input parameters such as the desired velocity, agents may still get very close to each other and have body contact even when we magnify the coefficient of repulsive force to extreme degrees.…”

“…So far, applications of modified crowd models have been extended to pandemic-related investigations in the contexts such as boarding and alighting of passengers in train stations ( Sun et al, 2021 ), boarding and alighting policies of airlines ( Islam et al, 2021b ), pedestrian traffic on university campuses and in academic buildings ( Castro and Ford, 2021 , Romero et al, 2020 ), foot traffic in shopping centres and supermarkets ( Tong et al, 2021 , Xiao et al, 2021 , Xu and Chraibi, 2020 ), and religious gatherings ( Al-Shaery et al, 2021 ). These applications have predominantly employed variations of social force pedestrian model ( Bouchnita and Jebrane, 2020 , Derjany et al, 2021 , Harweg et al, 2021 , Islam et al, 2021a , Si and Fang, 2021 , Tong et al, 2021 , Xiao et al, 2022 , Xiao et al, 2021 ), although this has not been a universal feature of pandemic-related simulation studies in crowd dynamics and other agent-based modelling paradigms such as those of cellular automata have been reported too ( Li and Yin, 2021 ).…”