Strategies in crowd and crowd structure

In an emergency situation, imitation of strategies of neighbours can lead to an order-disorder phase transition, where spatial clusters of pedestrians adopt the same strategy. We assume that there are two strategies, cooperating and competitive, which correspond to a smaller or larger desired velocity. The results of our simulations within the Social Force Model indicate that the ordered phase can be detected as an increase of spatial order of positions of the pedestrians in the crowd.

💡 Research Summary

The paper investigates how the imitation of neighbours’ behavioural strategies can trigger a collective order‑disorder phase transition in crowds during emergency evacuations. The authors simplify human decision‑making to two possible strategies: a “cooperative” strategy, associated with a lower desired walking speed, and a “competitive” strategy, associated with a higher desired speed. These strategies are embedded into the well‑established Social Force Model (SFM), which normally accounts for physical interactions such as repulsive forces and a driving term toward a target.

In the model each pedestrian i carries a binary state s_i∈{+1,−1} (cooperative = +1, competitive = −1). The desired speed is defined as v_d(s_i)=v_0