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In the early seventies, a substantial body of research was established on
pedestrian behavior and their interaction with the environment and other
pedestrians. These studies focused primarily on social and psychological
aspects of walking, such as the way pedestrians observe the walking
infrastructure via subliminal scanning, or may collaborate with other
pedestrians via subconscious communication. Also, attention was paid to the
way social and cultural differences affect different walking processes. For
the design of walking infrastructure, a working knowledge of the
characteristics of pedestrian flows is required in order to design
infrastructure as well as to assess its efficiency and safety. In
particular, a good understanding is required of the typical self-organizing
patterns that occur in pedestrian flows in order to predict how the flow
will behave under different circumstances. Available knowledge is generally
based on results of microscopic simulation studies rather than detailed
empirical or experimental research on how individual pedestrians act under a
variety of traffic flow or environmental conditions.
The main contributions of this paper are the experimental research results that provide more insight into these dynamic phenomena as well as exposing other forms of self-organization, i.e. in case of over-saturated bottlenecks or crossing pedestrian flows. It is shown how the resulting structures relate to states occurring in granular matter and solids, including their imperfections (so-called vacancies). It is shown how groups of pedestrians that are homogeneous in terms of desired walking speeds and direction form structures consisting of overlapping layers. This 'basic pattern' forms the basis of other more complex patterns emerging in multi-directional pedestrian flow, as is shown from the experimental results. A theory of self-organization in pedestrian flow is proposed, based on the assumption that each pedestrian aims to minimize his or hers predicted disutility of walking (i.e. the pedestrian economics): for all available options (e.g. accelerating, decelerating, changing direction, do nothing), a pedestrian chooses the option that will yield the smallest predicted disutility. In doing so, he or she values the different attributes characterizing the available options (e.g. risk to collide with another pedestrian, straying from the intended walking path, physical contact with other pedestrians, etc.) differently. Under specific conditions, we may expect that given this assumption, the pedestrian flow will evolve to an user-equilibrium state (which is either stable or meta-stable) in which no pedestrian can improve his or hers condition by unilaterally undertaking an action. |