Traffic dynamics of uni- and bidirectional pedestrian flows including dyad social groups in a ring-shaped corridor

Abstract

In this paper, we introduce dyad social groups into the experiment to mimic uni- and bidirectional pedestrian flows that are closer to real life. According to the experimental videos, different strategies of collision avoidance for dyads are observed and classified. Moreover, we observe an interesting lane-merging phenomenon in bidirectional scenarios. Fundamental diagrams are calculated based on two measurement methods, and further compared with previous individual experiments (without dyads), confirming the negative impact of social groups due to their inherent cohesion during the movement process. Then, group characteristics such as group distance and spatial alignment are analyzed under the influence of different global densities. It is interesting to note that the effect of density on spatial alignment distribution is opposite in uni- and bidirectional scenarios, i.e. the increasing density will make the distribution less scattered in the unidirectional flow, which is contrary to the phenomenon in the bidirectional flow. Finally, based on the time evolution of congestion level and crowd danger, they can be good indicators of transitions from disorder to order, especially in bidirectional scenarios. Furthermore, the differences between uni- and bidirectional flows can be well distinguished through the relations between density and congestion level, as well as crowd danger.

Analysis and modelling of macroscopic and microscopic dynamics of a pedestrian cross-flow

“…A l is given by half of the pedestrian maximum linear extension (for a circular body with radius R, A l = R; for an elliptical body with semi-axes A > B, A l = A), while B l is a parameter of the model that represents half of the leg swing length. Such an elliptical space is centred at the body centre of mass (elliptical body centre), and oriented in such a way that the B l axis overlaps with the velocity direction 17 . For each pedestrian pair {i, j}, and time t, assuming j ∈ V p j , the set of visible (i.e., located on i's front) pedestrians, we verify if their "leg swing space" overlap, and in case they do, we evaluate "how much they overlap" in the following way.…”

“…All the above cases are obviously very interesting and still present open questions. Even the behaviour in a simple corridor is not completely understood; see for example many works discussing conditions causing the observed variations in fundamental diagrams (density/velocity relations) [15,16,17]. Furthermore, when a second, opposite, flow is allowed, the dynamics becomes considerably more complex, and possibly not completely feasible to be analysed in controlled experiments (due to social norms on walking sides [18], stronger influence of social groups [19], etc.…”

“…When variables accounting for conditions close to reality are further added, things get even more complex, since route choice [20] or exit selection [21], walking impairment or disabilities [22], collaborative vs competitive behaviours [23], level of competitiveness [14], social bonds [17], available information [24], etc. have to be taken into account; all aspects that may even be impossible to realistically reproduce as a whole in a controlled experiment setting.…”

“…The proposed term can hardly be regarded as "long range", but we include it in this section because it is considered as part of the "basic" model 16. A rectangular shape could be used to decrease computational time 17. This means that, for an elliptical body, the body minor axis B is not necessarily aligned with B l , since we allow body direction and velocity direction to differ.…”

Walking in Social Groups: Role of Intra-Group Interactions

“…They conclude that the impact of social groups at a macro level is insignificant, whereas it is important to consider their impact at a micro level. (Ye et al, 2021) note that only one member of the dyad actively tries to resolve conflicts by either getting closer to their group member, rotating their body, or adjusting their spatial alignment from line-abreast to diagonal or river pattern. However, the trade-offs that people might be doing between the degree of communication and ease of navigation are still not clear, especially for groups with more than two members.…”