Conflict in pedestrian networks

Encouraging pedestrian activity is increasingly recognised as beneficial for public health, the environment and the economy. As our cities become more crowded, there is a need for urban planners to take into account more explicitly pedestrian needs. The term that is now in use is that a city should be ‘walkable’. For route planning, whereas much attention has been given to shortest path, in distance or time, much less attention has been paid to flow levels and the difficulties they pose on the route. This paper considers problems posed by conflicting paths, for example cross-traffic. We use network centrality measures to make a first estimate of differing levels of conflict posed at the network nodes. We take special note of the role of collective motion in determining network usage. A small case study illustrates the method

Extensional and intensional collectives and the de re/de dicto distinction

Expressions designating collectives, such as "the committee" or "the ships in the port", may be interpreted de re or de dicto, depending on context, according as they pick out collectives defined by their members or collectives defined by some criterion for membership. We call these E(xtensional)-collectives and I(ntensional)-collectives respectively, and in this paper we explore in depth the relationship between these two categories. In particular, we identify important respects in which they differ, regarding the nature of the dependence of the collective on its members, the nature of the parthood relation in which the members stand to the whole, and, from an application perspective, the different methods used for identifying the two forms of collective from large spatio-temporal data-sets

What can spatial collectives tell us about their environment?

Understanding how large groups of individuals move within their environment, and the social interactions that occur during this movement, is central to many fundamental interdisciplinary research questions; ranging from understanding the evolution of cooperation, to managing human crowd behaviour. If we could understand how groups of individuals interact with their environment, and any role that the environment plays in their behaviour, we could design and develop space to better suit their needs. Spatiotemporal datasets that record the movement of large groups of individuals are becoming increasingly available. A method, based on a set of coherence criteria, has previously been developed to identify different types of collective within such datasets. However, further investigations have revealed that the method can be used to reveal important information about the environment. This paper applies the method to a spatiotemporal dataset that records the movements of ships within the Solent, in the UK, over a twenty-four hour period to explore what can be inferred from the movement of groups of individuals, referred to as spatial collectives, regarding the environment