How many people can simultaneously move through a pedestrian space? The impact of complex flow situations on the shape of the fundamental diagram

Pedestrian crowding occurs more frequent. As a result of the increasing pedestrian demand in public space, the limits of pedestrian spaces are of increasing interest. Some research on the maximum demand that can flow through a cross-section has been presented, which mainly features simple movement base cases, low-density situations and/or a homogeneous crowd. Consequently, it is currently unclear to what extent their findings apply to heterogeneous high-density crowds, which are often encountered during real-world scenarios. The CrowdLimits experiment attempted to reproduce crowd movement dynamics of heterogeneous crowds experiencing higher densities than have been recorded up to this moment. Here, the aim was to study the impact of the three important differences between the current laboratory studies and real-world crowd dynamics in crowded pedestrian spaces simultaneously, namely crowd heterogeneity, high densities movements, and (more) complex movement base cases. This study shows that there are substantial differences in the maximum sustainable flow rate, and the maximum local and global sustainable density for distinct movement base cases and flow ratios. Moreover, the results provide evidence of that continuation of flow under very high densities can be recreated under laboratory conditions using a heterogeneous population of pedestrians. Besides, the experimental results indicate that the maximum global flow rate decreases when the scenario becomes more difficult (i.e. bidirectional to intersecting) and the collision avoidance opportunities decrease (i.e. 80-20 to 50-50 flow ratio). Thus, this paper concludes that the maximum flow rate of pedestrian infrastructures decreases with increasing complexity.