Segregation through space: A scope of the flow-based spatial interaction model

People are socially divided through urban space, where they experience segregation dynamically. By conceptualising mobilised social inclusion as the gravitational interactions between urban human flow patterns, this article introduces a framework for measuring the extent to which two trajectories interact with one another in daily activity space, in which a series of indices, theoretically equivalent to those developed in segregation research, are produced to capture the interaction potentials among various social groups from different perspectives. These scopes include absolute, relative and multi-group using pairs of places as analysis units, as well as place-based measurements that are very sensitive to the spatial configuration of the flow-based spatial interaction potentials. The application in the case of Greater London implies that the relative indices capture the spatial differentiation among various modes of interactions, portraying the between-domains exposure levels might be experienced by different occupations when they commute across places. The study demonstrates that mobilised interaction is influenced by between-domains mobility, and the proposed approach can provide a network understanding of social exposure through the edges between every two place nodes, going beyond existing place-based measurements. In addition, the changes between place-based results aggregated by origins and those determined by destinations showcase the dynamic shift of in-site exposure during peak hours. Though only commuting behaviours are demonstrated in this work, the framework introduced can be easily extended to the spatial interactions between any flow trajectories for any spatial unit, e.g., place (point-wise), place pairs (pair-wise), or specified routes (path-wise), within the activity space defined by time geography or the life-course domain approach.