Entropy analysis of the laminar movement in bidirectional pedestrian flow

With more and more large-scale activities conducted in the cities, the issue how to evaluate risk in activities has attracted a lot of researchers to investigate. Bidirectional flow can be commonly observed in mass gathering events, therefore it is of great importance to gain deeper insights into this kind of movement. In this manuscript, three kinds of entropy are introduced and used in order to measure the disorder and risk of bidirectional movement, namely position entropy, angle entropy and speed entropy. Larger entropy means more uncertainty and risk in the system. Entropy is applied in two counter-flow experiments in order to describe the level of randomness. It is found when the number of lanes transits from 4 to 3, there is a sharp increase in respect of entropy because occupants compete for the space to move forward. In order to testify the effect of position entropy, another scenario is calculated and small position entropy means steady bidirectional movement, which is in accordance with the realistic movement in experiment. The speed entropy is measured and similar trend can be observed by comparing with speed variance proposed by previous researchers. Furthermore, angle entropy is also investigated and relation between angle entropy and density is obtained. The proposed entropy can help quantify randomness of counter-flow movement and be beneficial forfor the managers to better deal with potential abnormal activities.