Searching for anisotropy in the density of walking pedestrians

In this contribution we analyze the spatial distribution and relative positioning of pedestrians in a laboratory experiment looking for anisotropic effects with respect to the walking direction. For this purpose, we compare the longitudinal and lateral extension of Voronoi cells as well as the frequency of longitudinal and lateral positioning of nearest neighbors at varying density. Our main finding is that the distance to the nearest neighbor varies stronger with density if the nearest neighbor is rather in longitudinal than when they are in lateral direction. Below a density of roughly 3/m2 a nearest neighbor is on average closer when positioned lateral than longitudinal, while it is the opposite when density is above this threshold value. Hence, apart from the threshold value, density has an anisotropic, walking direction-dependent aspect.